New Cosmetic Science

New Cosmetic Science

This Page Intentionally Left Blank

New Cosmetic Science Edited by

Takeo Mitsui, Ph.D. Former Senior Executive Director and Director of Research and Development Division, Shiseido Co., Ltd.

ELSEVIER A m s t e r d a m - Lausanne - New Y o r k - O x f o r d - Shannon - S i n g a p o r e - Tokyo

Notice The content of this book was based upon the latest information known to the authors as of the time it was written. However, information and knowledge changes constantly with the passing of time. In particular, the regulations applicable to cosmetic raw materials, pharmaceutical agents, cosmetic products and marketing activity vary considerably country by country and are subject to major revisions from time to time. Therefore, anyone who manufactures or sells cosmetic products must first investigate and confirm all applicable regulatory requirements. Although certain examples are provided in this book of raw materials, pharmaceutical agents, formulae, etc., these are provided for purposes of general reference only in order to explain concepts of cosmetic science. No representation or guarantee of any kind is made as to their stability, safety, efficacy or the effect of patent laws or other laws and regulations in the event of their actual use.

The Japanese edition was published by Nanzando Co. Ltd., 1993 Copyright © 1993 by Takeo Mitsui

P u b l i s h e d by: E l s e v i e r S c i e n c e B.V. P.O. B o x 211 1000 A E A m s t e r d a m The Netherlands

First edition 1997 S e c o n d i m p r e s s i o n 1998

I S B N 0 444 82654 8

© 1997 Elsevier Science B.V. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without the prior written permission of the publisher, Elsevier Science BV, Copyright and Permissions Department, P.O. Box 521, 1000 AM Amsterdam, The Netherlands. No responsibility is assumed by the publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein. Because of the rapid advances in the medical sciences, the publisher recommends that independent verification of diagnoses and drug dosages should be made. Special regulations for readers in the U.S.A.: This publication has been registered with the Copyright Clearance Center Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923. Information can be obtained from the CCC about conditions under which the photocopying of parts of this publication may be made in the U.S.A. All other copyright questions, including photocopying outside of the U.S.A., should be referred to the copyright owner, Elsevier Science BV, unless otherwise stated.

Printed in The Netherlands on acid-flee paper

Preface New Cosmetic Science was published 35 years after Cosmetic Science was edited by Tessaku Ikeda in 1957; during this interval, more than 30,000 copies of the various editions of Cosmetic Science have been sold and it is still regarded as a definitive work in this field. However, 14 years have passed since the late Dr. Ikeda made his final revisions in 1978. In these last few years, the field of cosmetic science, especially in Japan, has seen major changes, particularly in the development of new raw materials and new pharmaceutical agents, as well as in advances in manufacturing processes and technologies. The Congress of the International Federation of Societies of Cosmetic Chemists (IFSCC) in recent years have announced many important developments from Japan, and Japanese research papers have been awarded as the best paper at every Congress from 1986 to 1992. It is no exaggeration to say that cosmetic science in Japan has reached world top-class level. For these reasons, we have undertaken a comprehensive review of Dr. Ikeda's Cosmetic Science and have published this completely new book as New Cosmetic Science, New Cosmetic Science has been written to give as many people as possible, starting from scientists and technologists specializing in cosmetic research and manufacturing, students of cosmetic science, and people with a wide range of interests concerning cosmetics, a better understanding of the subject. Cosmetics, including toiletries, are closely connected with and are essential to daily life and the demand is increasing year-by-year. Many university departments of pharmacology now include lectures in cosmetic science and there is increasing general interest in the subject. Cosmetic science includes a variety of scientific disciplines starting with chemistry, pharmacology, and physical chemistry, as well as dermatology, biochemistry, physiology, engineering, analytical chemistry, fragrance chemistry, color science, and psychology. The relationship between these disciplines and cosmetics is described in Part I in New Cosmetic Science', in particular, three new chapters not described previously have been added. In addition to discussing the safety of cosmetics, the "Usefulness of Cosmetics", which is becoming a very important theme, is also described using a number of research examples. Cosmetic stability assessment is a central subject for cosmetic scientists and many aspects are based on knowledge gained over many years. The chapter on "Cosmetic Stability" has been written for a cosmetic researcher incorporating the latest findings. The last chapter of Part I is "Cosmetics and Information", which is particularly important in this information intensive age. Several databases, which are being used more

vi Preface to the English edition Toshihide Ikeda Hiroshi Itagaki Kenzo Ito Fujihiro Kanda Yoshihiro Kanda Shinobu Kato Yoshihisa Kimoto Kenji Kitamura Susumu Kobayashi Toshiaki Kobayashi

Hideo Nakajima Shoji Nakamura Tomiyuki Nanba Shoji Nishiyama Kimio Ohno Tomomi Okazaki Tsutomu Saito Izumi Sasaki Katsura Shimizu

Masahiro Tanida Katsuhiko Tokuda Akihito Torii Kenji Torii Keiichi Uehara Masaaki Uemura Youji Wachi Katsuyuki Yomogida Toshio Yoshioka

I would also like to thank Messrs. Shinji Nagashima, Yoshihiro Kanda and Tsuneo Suehiro of Shiseido Co., Ltd. for their assistance in all aspects of the editing of New Cosmetic Science. My thanks are also due to Alexander Cox for his cooperation in translating the Japanese edition into English. Finally, I would like to offer my gratitude to Ms. Yoshiko Adachi of Elsevier Science Japan in publishing the English Edition. Takeo Mitsui, Ph.D. Editor September 1996

Preface to the English edition It is now more than 3.5 years since the original pubhcation of New Cosmetic Science in Japan. During this time, it has been widely read by a great many cosmetic scientists and used as a text book or reference for several university cosmetic science courses. It has aheady been printed a second time in Japan. I am confident that the great interest in this book in Japan has been because, written by research scientists of the Shiseido Research Center who have a wealth of experience in research on cosmetic products and basic cosmetic technologies, it contains a good balance of several cutting edge technologies which are very useful in understanding cosmetic science as well as in the actual development of cosmetic products. New Cosmetic Science is now also receiving increasing attention in other countries and the number of inquires from abroad concerning it has been increasing in recent years. It has therefore been decided to publish an EngUsh edition. In its preparation, efforts have been made to make it easily understood by people of many different nationalities through slight amendments or additions to certain sections of various chapters, particularly the chapter on regulations governing cosmetics. The basic technologies discussed in Part I are all essential to cosmetic product development and the typical formulae in Part II are based on these technologies. However, if they are used as they are for cosmetic products, we cannot vouch for their safety, stability or efficacy, or that they comply with the applicable regulations or patent rights of any particular country. They were included as examples for purposes of illustration and background references. I hope that this book will prove useful to cosmetic scientists and others with an interest in cosmetics. I would like to express my great thanks to Dr. Tatsuya Ozawa, Senior Executive Director of Shiseido Co., Ltd. and Director of Research and Development Division as well as to the Shiseido research scientists whose names appear below for their contribution in the publication of the English edition. Satoru Akiu Yoshio Asaka Toshihide Ebisawa Minoru Fukuda Shoji Fukushima Fuminori Harusawa Masato Hatao Seiichi Hirose Izumi Horii Shinichi Ikeda

Yoshiyuki Kohno Masaaki Komatsu Sanae Kubo Shigenori Kumagai Yoshimaru Kumano Kiyoshi Miyazawa Hiroshi Momose Yoshihiro Morikawa Masako Naganuma Shinji Nagashima

Chiyomi Sugiyama Fukuji Suzuki Aiko Suzuki Yukitoshi Tada Toshio Takabayashi Tasuku Takamatsu Emiko Takasu Sadaki Takata Uhei Tamura Muneo Tanaka

viii Preface

widely than before, as well as books and magazines related to cosmetic science, are introduced. Part II deals with cosmetics from the viewpoint of usage including skin care cosmetics, makeup cosmetics, hair care cosmetics, fragrances, body cosmetics, and oral care cosmetics. Oral hygiene products such as toothpaste are classified as oral care cosmetics, while soaps, bath essences and salts, etc., are classified as body cosmetics. The product performance, types, main components, prescriptions and manufacturing methods are described for each item. As editor, I will be very happy if New Cosmetic Science is read by many people interested in cosmetics, and if it makes a contribution to developing cosmetic science. Finally, I would like to express my sincere appreciation to Mr. Takayoshi Toriumi, Representative Director and Ms. Keiko Kadowaki of Nanzando Co., Ltd. for their help and encouragement in publishing this book. Takeo Mitsui, Ph.D. Editor November 1992

Contents

Introduction 1. 2. 3. 4. 5. 6.

3

Purpose of cosmetics ......................................................................................... Meaning of cosmetics ........................................................................................ Classification ..................................................................................................... Quality characteristics and quality assurance .................................................... Development process of cosmetics ................................................................... Scientific background, technology and its future ..............................................

3 3 4

5 7 7

PART I Cosmetics and skin 1.1.

1.2.

1.3.

1.4.

1.5.

1.6.

13

Structure and functions of skin .......................................................................... 1.1 .l. Skin ...................................................................................................... I . 1.2. Keratinization ...................................................................................... 1.1.3. Sebaceous glands and sebum ............................................................... 1.1.4. Sweat glands and perspiration ............................................................. Biological functions of skin ............................................................................... 1.2.1. Protection ............................................................................................. 1.2.2. Thermoregulation ................................................................................ 1.2.3. Sensory perception ............................................................................... 1.2.4. Absorption ........................................................................................... 1.2.5. Other functions .................................................................................... Color of skin ...................................................................................................... 1.3.1. Skin color ............................................................................................. 1.3.2. Skin pigmentation mechanism ............................................................. 1.3.3. Methods for expressing skin color ....................................................... Methods for distinguishing skin condition ........................................................ 1.4.1. Methods for evaluating skin condition ................................................ 1.4.2. Classification of skin condition ........................................................... Acne ................................................................................................................... 1.5.1. Causes of acne ..................................................................................... 1.5.2. Development and formation of acne ................................................... 1.5.3. Skin care for acne ................................................................................ Ultraviolet light and skin ................................................................................... 1.6.1. Ultraviolet light .................................................................................... ix

13 13 15 17 18 19 19 20 20 20 21 21 21 22 24 24 25 28 28 29 30 31 32 32

Contents

X

1.6.2. Acute response to ultraviolet light ....................................................... 1.6.3. Chronic response to ultraviolet light ................................................... 1.6.4. Prevention of exposure to sunshine ..................................................... 1.7. Aging of skin ..................................................................................................... 1.7.1. Symptoms of aging .............................................................................. 1.7.2. Instrinsic aging and photoaging ........................................................... 1.7.3. External changes in aged skin .............................................................. 1.7.4. Aging changes of skin physiological functions ................................... 1.7.5. Prevention and treatment of skin aging ...............................................

.

35 37 38 38 38 39 40 44 45

2 Cosmetics and hair and nails

47

2.1. Generation of hair .............................................................................................. 2.1.1. Generation and types of hair ................................................................ 2.1.2. Composition of hair and the structure of hair follicles ........................ 2.1.3. Hair cycle ............................................................................................. .. 2.2. Form and composition of hair shaft ................................................................... 2.2.1. Form of hair ......................................................................................... 2.2.2. Color of hair ......................................................................................... 2.2.3. Structure of a hair shaft ....................................................................... 2.3. Chemical composition of hair ........................................................................... 2.3.1. Chemical composition of hair .............................................................. 2.3.2. Chemical bonds in hair ........................................................................ 2.4. Physical characteristics of hair .......................................................................... 2.4.1. Extensibility of hair ............................................................................. 2.4.2. Moisture absorption of hair ................................................................. 2.5. Hair damage ....................................................................................................... 2.5.1. Condition of hair damage .................................................................... 2.5.2. Hair damage and its causes .................................................................. 2.5.3. Split hair ............................................................................................... 2.6. Function and structure of nails .......................................................................... 2.6.1. Function and physiology of nails ......................................................... 2.6.2. Structure and composition of nails ...................................................... 2.6.3. Physical characteristics of nails ........................................................... 2.6.4. Nail damage .........................................................................................

47 47 48 50 51 51 52 53 56 56 58 59 59 60 61 61 61 64 66 66 66 68 68

.

3 Color and cosmetic color materials

70

3.1. Color .................................................................................................................. 3.1.1. Light and color ..................................................................................... 3.1.2. Color perception .................................................................................. 3.1.3. Color of coloring materials .................................................................. 3.1.4. Three attributes of color ...................................................................... 3.1.5. Expression ofcolor .............................................................................. 3.1.6. Color images and impression of color combinations .......................... 3.1.7. Makeup colors ..................................................................................... 3.2. Color materials ..................................................................................................

70 70 71 72 72 73 77 78 81

xi

Contents

3.2.1. 3.2.2. 3.2.3. 3.2.4. 3.2.5. 3.2.6. 3.2.7.

Classification of color materials .......................................................... Organic synthetic coloring agents ....................................................... Natural colors ....................................................................................... Inorganic pigments .............................................................................. Perlescent (nacreous) pigments ........................................................... Polymer powders ................................................................................. New functional pigments .....................................................................

.

82 82 86 88 93 94 96

4 Cosmetics and fragrances

99

4.1. Olfaction ............................................................................................................ 4 . I .1. Roles of olfaction ................................................................................. 4.1.2. Nature of olfaction ............................................................................... 4.1.3. Olfactory mechanism ........................................................................... 4.1.4. Body odor ............................................................................................ 4.2. Smell, fragrances and perfumery raw materials ................................................ 4.2.1. History of perfume ............................................................................... 4.2.2. Role and importance of fragrances in cosmetics ................................. 4.2.3. Physiological and psychological effects of odors ............................... 4.2.4. Classification of perfumery raw materials .......................................... 4.3. Natural perfumes ............................................................................................... 4.3.1. Major natural perfumes ....................................................................... 4.3.2. Manufacturing methods and general names ........................................ 4.3.3. Analysis of natural perfumes ............................................................... 4.4. Aroma chemicals ............................................................................................... 4.4.1. Typical aroma chemicals ..................................................................... 4.4.2. Advances in synthesis methods ........................................................... 4.5. Fragrance compounds ........................................................................................ 4.5.1. Base compounds .................................................................................. 4.5.2. Other base compounds ......................................................................... 4.6. Perfume creation ................................................................................................ 4.6.1. Creation ................................................................................................ 4.6.2. Preference ............................................................................................ 4.6.3. Fragrance strength and perfume dosage .............................................. 4.6.4. Odor and color changes ....................................................................... 4.6.5. Safety ...................................................................................................

99 99 100 100 100 101 101 101 102 103 104 104 104 108 111 111 111 111 114 115 116 116 118 118 118 119

.

5 Raw materials of cosmetics 5.1. Oily materials .................................................................................................... 5.1 .1. Oils and fats ......................................................................................... 5.1.2. Wax esters ............................................................................................ 5.1.3. Hydrocarbons ....................................................................................... 5.1.4. Higher fatty acids ................................................................................. 5.1.5. Higher alcohols .................................................................................... 5.1.6. Esters .................................................................................................... 5.1.7. Silicones ...............................................................................................

121 121 122 122 124 125 126 127 128

xii

5.2.

5.3.

5.4.

5.5. 5.6.

5.7. 5.8.

.

Contents

5.1.8. Others ................................................................................................... Surface active agents ......................................................................................... 5.2.1. Anionic surfactants .............................................................................. 5.2.2. Cationic surfactants ............................................................................. 5.2.3. Amphoteric surfactants ........................................................................ 5.2.4. Non-ionic surfactants ........................................................................... 5.2.5. Other surfactants .................................................................................. Humectants ........................................................................................................ 5.3.1. Glycerin ............................................................................................... 5.3.2. Propyleneglycol .................................................................................. 5.3.3. 1,3-Butylene glycol .............................................................................. 5.3.4. Polyethylene glycol ............................................................................. 5.3.5. Sorbitol ................................................................................................ 5.3.6. Sodium lactate ..................................................................................... 5.3.7. Sodium 2-pyrrolidone-5-carboxy late .................................................. 5.3.8. Sodium hyaluronate ............................................................................. Polymers ............................................................................................................ 5.4.1, Thickening agents ................................................................................ 5.4.2. Film formers ........................................................................................ Ultraviolet absorbents ........................................................................................ Antioxidants ....................................................................................................... 5.6.1, Auto-oxidation mechanism .................................................................. . . ........................................................................ 5.6.2. Prevention of oxidation 5.6.3. Confirmation of efficacy of antioxidants ............................................ Sequestering agents ........................................................................................... Other raw materials ........................................................................................... 5.8.1. Metallic soaps ......................................................................................

6 Cosmetics and pharmaceutical agents 6.1. Whitening agents ............................................................................................... 6.1.1. Arbutin ................................................................................................. 6.1.2. Kojic acid ............................................................................................. 6.1.3. Vitamin C and its derivatives .............................................................. 6.2. Hair growth promoters ....................................................................................... 6.2.1. Vasodilators ......................................................................................... 6.2.2. Nourishing agents ................................................................................ 6.2.3. Estrogens (follicle hormone) ............................................................... 6.2.4. Hair root activating agents ................................................................... 6.2.5. Humectants .......................................................................................... 6.3. Skin-care agents ................................................................................................. 6.3.1. Antiinflammatory agents ..................................................................... 6.3.2. Astringents ........................................................................................... 6.3.3. Refrigerants .......................................................................................... 6.3.4. Vitamins ............................................................................................... 6.3.5. Hormones ............................................................................................. 6.3.6. Antihistamines .....................................................................................

129 129 129 131 131 132 134 134 135 135 136 136 136 136 136 137 138 138 140 142 142 142 144 145 146 146 146

148 148 148 149 150 151 151 151 152 152 152 152 152 153 153 153 155 155

Contents

6.3.7. Others ................................................................................................... 6.4. Anti-acne agents ................................................................................................ 6.4.1. Sebum secretion inhibitors .................................................................. 6.4.2. Corneocyte desquamating agents ........................................................ 6.4.3. Antibacterial agents ............................................................................. 6.4.4. Others ................................................................................................... 6.5. Anti-dandruff and anti-itching agents ............................................................... 6.5.1. Corneocyte desquamating agents ........................................................ 6.5.2. Antiseborrheic agents ......................... ............................................. 6.5.3. Antibacterial agents ............................................................................. 6.5.4. Antiinflammatory agents ..................................................................... 6.5.5. Antipruritic agents ............................................................................... Antiperspirants and deodorants ......................................................................... 6.6. 6.6.1. Antiperspirants ..................................................................................... 6.6.2. Antibacterial agents ............................................................................. 6.6.3. Deodorants ........................................................................................... 6.7. Oral care agents ................................................................................................. 6.7. I . Anticariogenic agents .......................................................................... 6.7.2. Antiperiodontic agents ......................................................................... 6.7.3. Oral deodorants .................................................................................... 6.7.4. Antitarta agents .................................................................................... 6.7.5. Tar cleansing agents ............................................................................ 6.8. Others ................................................................................................................. 6.8.1. Vitamins ............................................ ............................................. 6.8.2. Hormones ............................................................................................. 6.8.3. Amino acids ......................................................................................... 6.8.4. Extracts from natural resources ...........................................................

.

7 Cosmetics and physical chemistry 7.1. Colloid and interface science of cosmetics ....................................................... 7 . I .1. Colloids and interfaces ........................................................................ 7.1.2. Properties of surfactants ...................................................................... 7.1.3. Solubilization and microemulsions ..................................................... 7.1.4. Emulsions ............................................................................................ 7.1.5. Liposomes (vesicle) ............................................................................. 7.1.6. Properties of powders .......................................................................... 7.2. Rheology of cosmetics ....................................................................................... 7.2.1, Meaning of rheology in cosmetics ....................................................... 7.2.2. Flow forms ........................................................................................... 7.2.3. Rheology measurement methods .........................................................

.

8 Stability of cosmetics 8.1. Stability of base formulae and its testing .......................................................... 8.1. 1. General preservation tests .................................................................... 8.1.2. General performance and effectiveness tests ......................................

... XI11

155 156 156 156 157 157 157 158 158 158 158 158 158 159 159 159 160 160 161 162 162 162 162 162 163 163 164

165 165 165 167 173 174 180 180 183 183 183 184

191 191 191 194

xiv

Contents

8.1.3. Aerosol stability tests ........................................................................... 8.1.4. Special accelerated stability tests ........................................................ 8.2. Stability of pharmaceutical agents and test methods ......................................... 8.2.1. Quality assurance for pharmaceutical agents in cosmetics ................. 8.2.2. Stability tests for quasi drug products ................................................. 8.3. Stability of mass-produced cosmetics ............................................................... 8.4. Assurance stability based on usage environment ..............................................

.

9 Preservation of cosmetics 9.1 . Need for adding preservatives to cosmetics ...................................................... 9.2. Primary and secondary contamination .............................................................. 9.3. Antimicrobial agents .......................................................................................... 9.3.1 . Preservatives ........................................................................................ 9.3.2. Disinfectants and germicides ............................................................... 9.3.3. Characteristics required of antimicrobial agents ................................. 9.4. Antimicrobial agents used in cosmetics ............................................................ 9.5. Methods for evaluating the effectiveness of preservatives ............................... 9.6. GMP and its validation ......................................................................................

.

10 Safety of cosmetics 10.1. Basic concept of cosmetic safety ....................................................................... 10.2. Safety test items and evaluation method ........................................................... 10.2.1. Skin irritation ....................................................................................... 10.2.2. Sensitization (allergenicity) ................................................................. 10.2.3. Phototoxicity ........................................................................................ 10.2.4. Photosensitization (photoallergenicity) ............................................... 10.2.5. Eye irritation ........................................................................................ 10.2.6. Toxicity ................................................................................................ 10.2.7. Mutagenicity ........................................................................................ . . ........................................................................... 10.2.8. Reproductive toxicity 10.2.9. Absorption, distribution, metabolism, excretion ................................. 10.2.10. Testing on humans (patch test, usage test) .......................................... 10.3. Animal test alternatives .....................................................................................

.

11 Usefulness of cosmetics I 1.1. Usefulness of cosmetics ..................................................................................... 11.2. Research on usefulness of cosmetics ................................................................. 11.2.1. Physiological usefulness ...................................................................... 11.2.2. Physicochemical usefulness ................................................................ 1I .2.3. Psychological usefulness ..................................................................... 1 1 .3. Examples of usefulness research ....................................................................... 11.3.1. Examples of research on physiological usefulness ............................. I 1.3.2. Examples of research on physicochemical usefulness ........................ 11.3.3. Examples of research on psychological usefulness ............................. 1I .4. Future direction of cosmetic usefulness ............................................................

194 195 196 196 197 197 198

199 199 200 201 201 201 202 202 205 206

209 209 210 210 211 212 212 213 213 214 214 215 215 216

218 218 218 218 219 219 220 220 227 231 233

Contents

.

xv

12 Cosmetics and containers

235

12.1. Characteristics required by cosmetic containers ............................................... 12.1.1. Quality maintenance ............................................................................ 12.1.2. Functional design ................................................................................. 12.1.3. Optimum packaging ............................................................................. 12.1.4. Economy .............................................................................................. 12.1.5. Sales promotion ................................................................................... 12.2. Types of cosmetic containers ............................................................................ 12.2.1. Narrow-mouth bottles (containers) ...................................................... 12.2.2. Wide-mouth bottles (containers) ......................................................... 12.2.3. Tubes .................................................................................................... 12.2.4. Tubular containers ............................................................................... 12.2.5. Powder containers ................................................................................ 12.2.6. Compact containers ............................................................................. 12.2.7. Stick containers .................................................................................... 12.2.8. Pencil containers .................................................................................. 12.2.9. Applicator containers ........................................................................... 12.3. Cosmetic container materials ............................................................................ 12.3.I . Types of materials ................................................................................ 12.3.2. Forming and processing methods ........................................................ 12.4. Design and quality assurance of cosmetic containers ....................................... 12.4.1. Container design procedure ................................................................. 12.4.2. Material test methods and specifications ............................................. 12.5. Trends in container materials ............................................................................ 12.5.1. Materials and processing methods ....................................................... 12.5.2. Environment friendliness .....................................................................

235 235 237 237 238 238 238 239 239 239 239 240 240 240 241 241 241 241 243 245 245 245 246 246 247

.

13 Aerosol technology in cosmetics

13.1. Principle of aerosols and their components ....................................................... 13.1.1. Principle of aerosols ............................................................................ 13.1.2. Components of an aerosol ................................................................... 13.2. Aerosol propellants ............................................................................................ 13.2.1. Liquefied gases .................................................................................... 13.2.2. Compressed gas ................................................................................... 13.3. Aerosol concentrates (discharged substances) .................................................. 13.3.1. Solubility test ....................................................................................... 13.3.2. Internal pressure test ............................................................................ 13.3.3. Discharge test ....................................................................................... 13.3.4. Low temperature test ........................................................................... 13.3.5. Other testing ......................................................................................... 13.4. Aerosol containers ............................................................................................. 13.4.1. Pressure-resistant containers ................................................................ 13.4.2. Valves, actuators, spouts and caps ....................................................... 13.5. Regulations on aerosols ..................................................................................... 13.6. Aerosol manufacturing methods ........................................................................

248 248 248 249 249 249 250 250 251 251 251 251 251 251 251 252 253 254

xvi

Contents

13.6.1. Manufacturing processes ..................................................................... 13.6.2. Filling methods for propellant gas ....................................................... 13.7. Precautions when using aerosol cosmetics ........................................................ 13.8. Recent developments in aerosol technology ..................................................... 13.8.1, Special aerosol containers ................................................................... 13.8.2. Making aerosols environment friendly ................................................

.

14 Analytical chemistry of cosmetics 14.1. Analysis of cosmetics ........................................................................................ 14.1.1. General separation techniques ............................................................. 14.1.2. Column chromatography ..................................................................... 14.1.3. Gas chromatography ............................................................................ 14.1.4. High performance liquid chromatography .......................................... 14.1.5. X-ray diffractiometry ........................................................................... 14.1.6. Infrared spectrophotometry ................................................................. 14.1.7. Nuclear magnetic resonance ................................................................ 14.1.8. Mass spectrometry ............................................................................... 14.1.9. Atomic emission spectrophotometry, atomic absorption spectrophotometry ........................................................................................... 14.1.10. Summary of analysis on cosmetics ...................................................... 14.2. Analysis of skin and hair ................................................................................... 14.2.1. Analysis of skin ................................................................................... 14.2.2. Analysis of hair .................................................................................... 14.3. Automation of analysis ......................................................................................

.

15 Cosmetic manufacturing equipment 15.1. Grinders ............................................................................................................. 15.2. Powder mixing equipment ................................................................................. 15.3. Dispersion and emulsification equipment ......................................................... 15.3.1. Propeller mixer .................................................................................... 15.3.2. Disper ................................................................................................... 15.3.3. Homomixer .......................................................................................... 15.3.4. Homogenizer ........................................................................................ 15.3.5. Colloid mill .......................................................................................... 15.3.6. Pebble mill ........................................................................................... 15.3.7. Ultrasonic emulsifier ........................................................................... 15.4. Kneading equipment .......................................................................................... 15.4.1. Kneader ................................................................................................ 15.4.2. Roller ................................................................................................... 15.4.3. Gyratory grinder .................................................................................. 15.5. Cooling equipment ............................................................................................ 15.5.1. Cooling equipment employing stirring ................................................ 15.5.2. Cooling equipment employing heat exchange ..................................... 15.6. Molding machines ............................................................................................. 15.6.1. Lipstick molding machines ..................................................................

254 255 255 256 256 256

257 257 258 259 260 263 266 268 268 270 272 272 273 273 276 277

280 281 281 283 283 283 284 284 285 285 285 285 285 285 285 285 286 286 288 288

Contents

xvii

15.6.2. Foundation molding machines ............................................................. 15.7. Filling and packaging machines ........................................................................

289 291

.

16 Regulations on cosmetics ~

16.1. Regulations concerning cosmetics in Japan ...................................................... 16.1.1. Regulations in Pharmaceutical Affairs Law concerning cosmetics and quasi-drug products ....................................................................... 16.1.2. Regulations on manufacture and sale of cosmetics and quasi-drug products ................................................................................................ 16.2. Laws relating to cosmetics in Japan .................................................................. 16.2.1. Regulations relating to raw materials .................................................. 16.2.2. Laws relating to product contents ........................................................ 16.2.3. Regulations concerning containers ...................................................... 16.2.4. Regulations on marketing .................................................................... 16.3. Regulations on cosmetics in other countries (Asia, Oceania, North America, South America and Europe) .............................................................................. 16.3.1. Asia ...................................................................................................... 16.3.2. Oceania ................................................................................................ 16.3.3. North America ..................................................................................... 16.3.4. South America ..................................................................................... 16.3.5. Europe ..................................................................................................

.

17 Cosmetics and information 17.1. Importance of information in research and development .................................. 17.1.1. Documentation activities ..................................................................... 17.1.2. Information sources ............................................................................. 17.2. Books and journals containing cosmetic-related information ........................... 17.2.1. Books (monographs) ............................................................................ 17.2.2. Journals ................................................................................................ 17.3. Databases ........................................................................................................... 17.3.1. Definition of a database ....................................................................... 17.3.2. On-line information retrieval systems .................................................

292 292 294 295 297 298 298 302 303 304 304 306 307 307 307

310 310 310 311 312 314 314 316 316 316

PART I1

.

1 Skin care cosmetics 1 .1 . Purposes. functions and roles of skin care cosmetics ........................................ 1.1.1. Purposes of skin care cosmetics .......................................................... 1.1.2. Functions of skin care cosmetics ......................................................... 1. I .3. Roles of skin care cosmetics ................................................................ 1.2. Face cleansing cosmetics ................................................................................... 1.2.1. Purposes and functions of face cleansing cosmetics ........................... 1.2.2. Main ingredients of cleansing foams ................................................... 1.2.3. General manufacturing methods for cleansing foams ......................... 1.2.4. Types of cleansing foam ......................................................................

319 319 319 320 320 323 323 323 324 325

xviii

Contents

1.3. Lotion ................................................................................................................. 1.3.1. Purposes and functions of lotion ......................................................... 1.3.2. Main ingredients of lotions .................................................................. 1.3.3. General methods for manufacturing lotions ........................................ 1.3.4. Types of lotion ..................................................................................... 1.4. Milky lotions...................................................................................................... 1.4.1. Purposes and functions of milky lotions.............................................. 1.4.2. Main ingredients of milky lotions ....................................................... 1.4.3. General manufacturing methods for milky lotions.............................. 1.4.4. Types of milky lotion ........................................................................... 1.5. Creams ............................................................................................................... 1.5.1. Purposes and functions of creams ....................................................... 1.5.2. Main ingredients of creams ................................................................. 1 S.3. General manufacturing methods for creams........................................ 1.5.4. Types of cream .................................................................................... 1.6. Gels .................................................................................................................... 1.6.1. Purposes and functions of gels ............................................................ 1.6.2. Main ingredients of gels ...................................................................... 1.6.3. General manufacturing methods for gels ............................................. 1.6.4. Types of gel ......................................................................................... 1.7. Essences (beauty lotions)................................................................................... 1.7.1. Purposes and functions of essences ..................................................... 1.7.2. Main ingredients of essences ............................................................... 1.7.3. General manufacturing methods for essences ..................................... 1.7.4. Types of essence .................................................................................. 1.8. Packs and masks ................................................................................................ 1.8.1. Purposes and functions of packs and masks ........................................ 1.8.2. Main ingredients of packs and masks .................................................. 1.8.3. General manufacturing methods for packs and masks ........................ 1.8.4. Types of pack and mask ...................................................................... 1.9. Shaving" cosmetics ............................................................................................. 1.9.1. Purposes and functions of shaving cosmetics...................................... 1.9.2. Types of shaving cosmetics ................................................................. I .10. Other cosmetics .................................................................................................

.

2 Makeup cosmetics 2.1. 2.2. 2.3. 2.4. 2.5.

History of makeup cosmetics ............................................................................ Types and functions of makeup cosmetics ........................................................ Types and forms of makeup cosmetics ............................................................. Raw materials used in makeup cosmetics ......................................................... Face powder and pressed powder ...................................................................... 2.5.1. Loose powder ....................................................................................... 2.5.2. Compact powder .................................................................................. 2.5.3. Paper sheet-type face powder .............................................................. 2.5.4. Liquid face powder .............................................................................. 2.5.5. Other powder cosmetics ......................................................................

327 327 328 330 330 335 335 337 338 339 341 341 342 343 345 351 351 351 353 353 354 354 354 355 355 357 357 359 359 360 363 363 363 367

370 370 370 371 371 375 376 376 377 371 377

Contents

2.6. Foundations ........................................................................................................ 2.6.1. Powdery foundations ........................................................................... 2.6.2. Dual-use foundations ........................................................................... 2.6.3. Cake-type foundations ......................................................................... 2.6.4. Oil-based foundations .......................................................................... 2.6.5. O/W emulsion foundations .................................................................. 2.6.6. W/O emulsion foundations ............................................ .......... Lipsticks and rouge ............................................................................................ 2.7. 2.7.1. History of lipstick ................................................................................ 2.7.2. Quality requirements for lipsticks ....................................................... . . 2.7.3. Raw materials of lipsticks .................................................................... 2.8. Rouges (rouge. cheek color and blush-on products) ......................................... 2.9. Eye makeup ....................................................................................................... 2.9.1. History and types ................................................................................. 2.9.2. Points for attention with eye makeup products ................................... 2.9.3. Eyeliner ................................................................................................ 2.9.4. Mascara .......................................................................................... 2.9.5. Eye shadow .......................................................................................... 2.9.6. Eyebrow cosmetics .............................................................................. 2.9.7. Other products ...................................................................... 2.10. Manicure preparations ....................................................................................... 2.10.1. Functions and types ............................................................................. 2.102. Nail enamel .......................................................................................... 2.10.3. Enamel remover ................................................................................... 2.10.4. Nail treatment ...................................................................................... 2.103. Other products .....................................................................................

.

3 Hair care cosmetics

3.1. Hair cleansing cosmetics ................................................................................... 3.1.1, Shampoo .............................................................................................. 3.1.2. Rinses ................................................................................................... 3.1.3. One-step shampoo (shampoo having both shampoo and rinse functions) ................................................................................ 3.2. Hair growth promoters ....................................................................................... 3.2.1. Introduction ................................................................................ 3.2.2. Types of hair growth promoter ............................................................ 3.2.3. Causes of hair loss ...................................................................... 3.2.4. Active ingredients of hair growth promoters ....................................... 3.2.5. Methods of evaluating hair growth promoters .................................... 3.3. Hair grooming cosmetics ................................................................................... 3.3.1. Types of hair styling preparation ....................................... 3.3.2. Types of hair treatment preparation ................................... 3.4. Permanent waving lotion ................................................................. 3.4.1. History ................................................................................................. 3.4.2. Permanent waving mechanism ................................................. 3.4.3. Types of permanent waving lotion ......................................................

xix

378 379 380

381 382 383 384 385 385 386 386 388 390 390 390 391 393 395 396 398 398 398 399 402 403 403

406 406 407 410 412 413 413 414 414 415 416 418 418 424 426 426 421 428

xx

Contents

3.5. Hair color. hair bleach ....................................................................................... 3.5.1. History ................................................................................................. 3.5.2. Classifications of hair color and their mechanisms ............................. 3.5.3. Types of hair color ............................................................................... 3.5.4. Hair bleach ...........................................................................................

.

4 Fragrance products 4.1. Types of fragrance product ................................................................................ 4.2. Perfume .............................................................................................................. 4.2.1. Manufacturing methods for perfumes ................................................. 4.2.2. Alcohol used for perfumes ................................................................... 4.2.3. Classification of perfume ..................................................................... 4.2.4. Choosing a perfume ............................................................................. 4.2.5. Wearing perfume ................................................................................. 4.2.6. Keeping a perfume at its best .............................................................. 4.3. Men’s cologne ...................................................................................................

.

430 430 431 432 436

439 439 439 440 440 441 442 442 442 445

5 Body cosmetics

446

5.1. Soap ................................................................................................................... 5.1.1. History of soap ..................................................................................... 5.1.2. Raw materials of soap .......................................................................... 5.1.3. Soap manufacturing methods .............................................................. 5.1.4. Properties of soap ................................................................................ 5.1.5. Types of soap ....................................................................................... 5.2. Body shampoo ................................................................................................... 5.2.1. Functions required of body shampoos ................................................. 5.2.2. Types of body shampoo ....................................................................... 5.2.3. Main ingredients of body shampoo ..................................................... 5.3. Suncare products ................................................................................................ 5.3.1. Methods for assessing protection against ultraviolet rays ................... 5.3.2. Types of suncare base .......................................................................... 5.3.3. Types of suncare product ..................................................................... 5.4. Hand care products ............................................................................................ 5.5. Deodorant cosmetics .......................................................................................... 5.5.1. Body odor ............................................................................................ 5.5.2. Functions and ingredients of deodorant cosmetics .............................. 5.5.3. Types of deodorant cosmetics ............................................................. 5.6. Bleach and depilatories ...................................................................................... 5.6.1. Bleach (or discolor) ............................................................................. 5.6.2. Depilatories .......................................................................................... 5.7. Bath preparations ............................................................................................... 5.7.1. History and purposes of bath preparations .......................................... 5.7.2. Types and functions of bath preparations ............................................ 5.8. Insect repellents .................................................................................................

446 446 447 448 450 450 453 454 455 455 457 457 459 460 464 466 466 466 467 470 470 470 473 473 474 477

Contents

.

6 Oral care cosmetics

XXl

479

6.1. Dentifrices ......................................................................................................... 6.1.1. History of dentifrices ........................................................................... 6.1.2. Classification of oral cleansing products ............................................. 6.1.3. Dentifrices............................................................................................ 6.1.4. Mouthwash ........................................................................................... 6.2. Mouth freshener.................................................................................................

479 479 479 480 487 489

Index ...........................................................................................................................

491

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Introduction

1. Purpose of cosmetics 2. Meaning of cosmetics 3. Classification 4. Quality characteristics and quality assurance 5. Development process of cosmetics 6. Scientific background, technology and its future

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Introduction

1. Purpose of cosmetics Cosmetics are becoming of more importance in daily life; they are used regularly by increasing numbers of people and very large quantities are consumed each year. When were cosmetics first used by people? Even if we examine the history of cosmetics, it is extremely difficult to say when cosmetics were first used. Archaeological excavations confirm that they were used in the early stone age and we can safely assume that cosmetics have a very long history. Why did early societies use cosmetics? If we examine the purpose of cosmetics, the most obvious is protection of the body from the elements of nature, such as heat and sunlight. Early people painted themselves with oils or mixtures of oils, clays and plant materials to protect themselves against dryness from cold, burns from strong sunlight, and irritation from insect bites. Additionally, cosmetics were used for religious purposes. Fragrant woods for example were burnt to produce smoke and incense that would ward off evil spirits. Further protection was afforded to an individual by painting the body to guard against evil. As societies came into the age of enlightenment, however, most of these purpose of cosmetics disappeared. The main purposes for using cosmetics in modern society are for personal hygiene, to enhance attractiveness through use of makeup, to improve selfesteem and promote tranquillity, to protect skin and hair from damaging ultraviolet light, pollutants, and other environmental factor, to prevent aging, and in general to help people enjoy a more full and rewarding life.

2. Meaning of cosmetics How do we define a cosmetic? The definition of cosmetic under the law varies slightly between countries but in general terms "cosmetic" means any article intended to be used by means of rubbing, sprinkling or by similar application to the human body for cleaning, beautifying, promoting attractiveness, altering the appearance of the human body, and for maintaining health of the skin and hair, provided that the action of the article on the human body is mild. The Japanese Pharmaceutical Affairs Law regulates both cosmetics and so-called quasi-drugs. Quasi-drugs are products which are applied to the body for the purposes of cleaning teeth, deodorants, and hair colors, etc., but they "should be for alleviation of conditions

4 New cosmetic science

of the body but not for prevention and treatment of illness; they should not be designed to affect body structure and functions" The current Pharmaceutical Affairs Law makes a clear distinction between cosmetics, quasi-drugs, and pharmaceuticals. The former two categories of product are for use by healthy people to maintain personal hygiene and to maintain a favorable personal appearance. Consequently the physiological activities of cosmetics must be mild. In contrast, pharmaceutical drugs are used for treatment and prevention of illness and they have an effect on the structure and functions of the body. Since cosmetics and quasi-drugs are often used on a daily basis over long periods of time, safety without side effects is of paramount importance, and they must be completely safe without side effects. By contrast, pharmaceutical drugs for medical use are used only over short time periods to treat medical conditions. Their primary purpose is to cure illness, and they must therefore be therapeutically effective. Sometimes slight side effects of these drugs cannot be avoided. In summary, cosmetics and quasi-drugs are quite different from pharmaceutical drugs in use, purpose, and effects. New Cosmetics Science describes both cosmetics and quasi-drugs and when there is no particular reason for classifying these two groups of products separately, they are called cosmetics for convenience.

3. Classification Cosmetics (including quasi-drugs) can be classified according to their use and area of application. In addition, they can be classified by composition and structure. However, New Cosmetics Science uses the system shown in Table 1 based on usage and classifies cosmetics into skin care cosmetics, makeup cosmetics, body cosmetics, hair care cosmetics, oral cosmetics and fragrances. Skin care cosmetics are called facial cosmetics and they are mainly used on the face. There are three main usage purposes: cleansing, skin balance, and protection. Makeup cosmetic are mainly used on the face. Other makeup cosmetics include nail enamel. Face makeups are divided into base makeup and point makeups. Body cosmetics include suncare and suntan cosmetics, antiperspirants, deodorants, hair remover, bleaches depilatories, soaps, hand care products and bath preparations. A special product in the body cosmetics group is insect repellents. Hair care cosmetics include shampoos, treatments, and hair styling preparations as well as permanent wave agents and hair dyes. Other products in the group include hair growth promoters and scalp treatments. Oral care cosmetics primarily include toothpastes and products such as mouth washes. Fragrances are mainly used on the body but sometimes on the scalp hair and earlobes. Typical fragrance cosmetics are perfumes, but there are also eau de colognes made by varying the amount of fragrance used. These cosmetics are all used in daily life. The value of cosmetic shipments in Japan is second only to that in the USA. In terms of the value by type, skin care cosmetics are the largest followed by hair care cosmetics and makeups. Fragrances such as perfumes and

Introduction to cosmetic science Table 1. Classincation of cosmetics

Classification

Skin care cosmetics

Makeup cosmetics CO 5-'

Body cosmetics

1 3 Hair care Cosmetics OS

u

Scalp care Cosmetics

Oral care Cosmetics Fragrances

Main Products

Usage Cleansers

Face Cleansing Creams and Foams

Conditioners

Lotions, Packs, Massage Creams

Protectors

Milky Lotions, Moisture Creams

Base makeups

Foundations, Face Powders

Point Makeups

Lipstick, Blushers, Eye Shadow, Eye Liners

Nail Care

Nail Enamels, Nail Polish Removers

Bath

Soaps, Liquid Cleansers, Bath Preparations

Suncares and Suntans

Sunscreen Creams, Sun Oils

Antiperspirants and Deodorants

Deodorant Sprays

Bleaching, Depilatory

Bleaching Creams, Depilatory Creams

Insect Repellents

Insect Repellent Lotions and Sprays

Cleansing

Shampoos

Treatments

Rinses, Hair Treatments

Hair Styling

Hair Mousses® , Hair Liquids, Pomades

Permanent Waves

Permanent Wave Lotions (Agent No.l, No.2)

Hair Colors and Bleaches

Hair Colors, Hair Bleaches, Color Rinses

Hair Growth Promoters

Hair Growth Promoters, Hair Tonics

Treatments

Scalp Treatments

Toothpastes

Toothpastes

Mouthwashes

Mouthwashes

Fragrances

Perfumes, Eau de Colognes

eau de colognes are used less compared to the USA and Europe. This may be because of differences in lifestyle and body constitution.

4. Quality characteristics and quality assurance 4.1. Quality characteristics of cosmetics Generally, "quality" is determined by the satisfaction of the user (consumer). In the industrial situation, quality is determined at three points: (1) design, (2) manufacture and (3) sales. From each point, there are requirements necessary to satisfy the high quality characteristics. Economics and market timing are also important factors to consider. When designing, manufacturing and marketing cosmetics, the basic quality requirements are safety, stability, efficacy, and usability (feeling and ease of use); usability includes preference factors such as smell, color, and package design, which are determined by the user's personal taste. The quality characteristics are summarized in Table 2.

5

6

New cosmetic

science Table 2. Quality characteristics of cosmetics

Safety

Lack of Skin irritation, Skin sensitivity, Oral toxicity, Mixing with other materials, Harmlessness

Stability

Quality change. Color change. Smell change. Bacterial contamination, etc.

Usability

1. Feeling (sensibility, moisturizing, smoothness) 2. Ease-of-Use(form, size, weight, composition, performance, portability, etc.) 3. Preference (smell, color, design, etc.)

Efficacy

Moisturizing effect, UV protective effect, cleansing effect, coloring effect, etc.

Table 3(1). Cosmetics quality assurance

—Safety Assurance a; o 03

m—

) Dry skin

Dry-oily skin

Low water content (dry/rough skin) Fig. 1.10. Basic principles of skin classification.

some patients, acne can cause psychological upset, and it can often affect daily and social life. From the cosmetic aspect, fast and appropriate treatment is essential in speeding recovery to normal appearance. 1,5.1. Causes of acne To determine the best treatment for acne, it is essential to understand the causes of acne, which vary from individual to individual. Several causes are interdependent, but there are three principal factors outlined below. 1.5.1.1. Hyperactive sebaceous glands (overactive lipid secretion) The sebaceous glands produce sebum continuously. Sebum is secreted from the sebaceous gland duct and makes its way to the skin surface via the hair follicle pore. Testosterone promotes sebum synthesis and secretion and, consequently the sebaceous glands become extremely active at puberty (age 10-16). In particular, the sebaceous glands of areas such as the face, back and chest become very active and sometimes the balance between the amount of sebum produced and the sebum secretion ability cannot be maintained as a result of the hypersecretion. As a result, the secretion of sebum is disturbed, and sebum blocks the hair follicle resulting in inflammation. In adult males the amount of lipid secreted is usually fixed by the activity of testosterone from the testes, but in females, the amount of luteinizing hormone increases rapidly immediately after ovulation, which stimulates the sebaceous glands and increases sebum secretion, resulting in a sudden worsening of acne before menstruation. 1.5.1.2. Hyperkeratosis (accelerated keratinization) at hair infundibulum Hyperkeratosis occurs easily at the infundibulum of the hair follicle and the resulting thickened horny layer or horny materials obstruct the hair follicle pore, causing comedones. If horny materials block the hair follicle pore or duct of the sebaceous gland, or if it becomes narrowed, the sebum cannot be normally excreted, resulting in an obstruction at the hair infundibulum causing an increase in bacterium acnes. These bacilli produce materials that induce inflammation and stimulate the epidermal cells of the infundibu-

30

New cosmetic science

lum, resulting in further hyperkeratotic change. Since keratinization is promoted by physical stimulation and UV light, acne often becomes suddenly worse after the sufferer has been exposed to excessive sunlight at the seaside or in mountains. In addition, leaving the face unclean can often cause inflammation by allowing blockage of the hair follicle pore. 1.5.1.3. Effect of bacteria When sebum accumulates as a result of either excess secretion or hyperkeratosis at the hair infundibulum, the numbers of acne-causing rod bacteria (bacterium acnes) and the coccal bacteria found in the hair duct and on the skin both increase. The lipases of these bacteria break down the triglycerides in the sebum to form free fatty acids resulting in inflammation. Fig. 1.11 compares the skin surface lipid composition in acne and in normal skin. The skin surface of the person with acne has a high level of free fatty acids and a low level of triglycerides. Free fatty acids affect the skin of the hair infundibulum, and the hair infundibulum is damaged by production of various enzymes resulting in inflammation of the connective tissues surrounding the hair infundibulum. Consequently, although bacteria are not the direct cause of acne, they make slight acne worse and induce pustular acne. Each of the above three factors can cause acne independently, but they can also have a complex interaction making the acne even worse. Additionally, there are other causal factors including genetic factors, food, overwork and stress. 1.5.2. Development and formation of acne As described in the previous section on the causes of acne, overactive secretion of sebum coupled with hyperkeratosis causes the hair pores to become narrowed and blocked, resulting in the early first stage of acne called a comedo (Fig. 1.12b,c). Subsequently, the comedo damages and effects the surrounding tissues resulting in inflammation of the tissues surrounding the opening of the sebaceous gland (Fig. 1.12d). This results in an erythematous (red) papule. If this condition progresses, the horny materials and the sebum blocking the hair infundibulum overflows into the dermis to form a pustule (Fig. 1.12e). When bacteria invade the dermis, leukocytes attack the bacteria to form pus. Pus

Cholesterol Cholesterol esters Squalene

Female acne * (17-23 years) o Normal female (20-27 years)

* 0

A

Free fatty acids

\

Wax esters Triglycerides Diglycerides pp Monoglycerides //

'^^"*^ —

^ITi^^^^

— 1

10

20

30

Z—^^**^

1

40

Fig. 1.11. Skin surface lipid composition.

1

50

1—

60%

Cosmetics and skin 31 Precondition to comedos Horny layer

Horny layer thickening in hair pore

Sebaceous gland Hair follicle

(a)

Comedo formation Blackhead

Whitehead plug*

Inflammation

Plug*

Inflammation

Surface blackened by oxidation

Papule

Pustule

Bacterial increase

(d)

VU

(e)

*plug : Keratin and sebum mixture Fig. 1.12 Types of acne.

accumulates in the dermis to form a large raised painful pustule (Fig. 1.12f). When the large pustule subsequently heals, granulation often occurs and a scar remains. 1.5.3.

Skin care for

acne

When the case of acne is particularly severe, treatment with anti-inflammatory drugs may be required. Considering the development and formation of acne described above, good skin care is extremely important in preventing acne and in helping a person recover from acne. (1) Always keep skin clean (a) Clean face with antibacterial cleanser. (b) Style hair so that it does not directly touch the forehead and face. (c) Keep items such as pillows that touch the face and hair directly clean. (d) Do not touch inflamed skin with the fingers.

32 New cosmetic science

(2)

Use of cosmetics (a) Use non-greasy cosmetics formulated especially for acne containing germicidal agents and that suppress lipid production. (b) If oily foundation is applied too thickly, the fine particles will enter and block the hair pores. (3) Decreasing consumption of fatty, sweet and starchy foods (a) Reduce consumption of fatty foods such as fatty meat, nuts, chocolate, and cocoa. (4) Other Reduce stress such as that associated with overwork, overexercise.

1.6. Ultraviolet light and skin 1.6.1. Ultraviolet light Ultraviolet (UV) light is light at wavelengths shorter than visible light; it is divided (Fig. 1.13) into three regions: UV-C (200-280 nm), UV-B (280-320 nm) and UV-A (320400 nm). The shorter wavelengths in UV light reaching the earth from the sun are absorbed by the ozone layer in the upper atmosphere. The shortest UV wavelengths striking the skin are in the range of 290-300 nm and the energy of the UV-B components is about 1/10 to 1/20 that of the UV-A content. However, with increasing damage to the ozone layer caused by man-made gases like flon (chlorofuorocarbon), the filtering efficiency of the ozone layer is decreasing and there is an increase in the very short wavelengths reaching the skin surface which is believed to be inducing more cases of skin

Not reaching Earth surface ^-

Fig. 1.13. Spectrum of sunlight.

Cosmetics and skin 33

o•

X3

Q;

u

-lr->

U

O

c^

-^ o

O -5 ^

9

10

11

12

13

14

15

16

17

O

18 Time

Fig. 1.14. Hourly variation in amount of UV light. Source: Shiseido Lab., Average for Sunny Day June 1987 in Yokohama.

cancer. A 2% increase in the UV levels caused by a 1% decrease in the ozone layer is estimated to result in a 3% increase in the number of skin cancer cases. The strength and amount of UV light vary greatly according to the geographic position, season and time of day. In other words, the relationship between the position of the sun and the earth, and the weather play a major role. Fig. 1.14 shows the hourly variation (sunny day) in UV light and Table 1.4 shows the seasonal variation^^^. In Japan, the distribution peaks at about 12:00h but about half of the daily amount of UV light is received between 10:00h and 14:00h. The seasonal variation fluctuates widely depending Table 1.4. Amount of UV-A and UV-B in sunlight (1981 Yokohama) Month

UV-B (cal/cmVday)

UV-A (cal/cmVday)

1 2 3 4 5 6 7 8 9 10 11 12

0.55 0.58 1.10 1.69 1.61 1.09 1.64 1.46 1.19 1.01 0.39 0.40

10.93 11.45 17.21 23.13 21.65 16.27 22.87 21.50 14.96 13.22 6.97 47.43

Average

1.05

15.63

Measured using PH-11 M-2 AT Integrating UV Meter

34

New cosmetic

science

Table 1.5. Monthly variation in UV wavelengths (300 to 400 nm) in various Japanese cities

City

Asahikawa

Akita

Matsumoto Yokohama

Osaka

Miyazaki

Naha

43.5°N 112 m

39.4°N 9m

3.2°N 610 m

35.3°N 39 m

34.4°N 23 m

31.6°N 7m

26.rN 35 m

January February March April May June July August September October November December

133.1 268.5 587.7 636.8 748.7 818.0 816.9 698.0 520.0 354.4 173.0 130.5

141.7 254.9 595.9 814.1 913.0 951.4 863.7 937.0 675.2 507.2 275.3 175.3

408.4 511.8 729.8 862.2 1114.2 988.2 877.1 896.4 602.6 561.0 401.6 366.7

308.9 368.1 516.4 691.1 839.5 598.8 661.3 713.1 449.9 431.3 274.8 255.6

342.0 449.4 644.5 804.2 1009.2 912.8 848.3 887.5 564.6 539.2 369.5 311.2

474.7 496.0 647.4 799.7 951.5 871.3 975.9 953.0 646.9 594.1 433.2 441.5

410.6 420.8 615.5 691.3 881.2 872.8 994.7 963.3 741.2 642.1 477.3 385.4

Whole Year

5,886 96%

7,105 116%

8,339 137%

6,109 100%

7,236 118%

8,285 136%

8,076 132%

Latitude Altitude

Average

317.1 355.6 619.6 754.2 922.5 859.0 882.6 884.0 600.1 518.5 343.5 255.2

cal/cmVmonth or year

upon the weather conditions prevailing in an area. Although the amount of UV radiation falls in the June wet season, the seasonal peak is found between May and July, and the lowest of UV radiation is found between December and February. In addition, altitude and latitude have a large effect upon UV radiation. More UV light particularly UV-B, is received at higher altitudes and lower latitudes (Table 1.5). When a person is bathed in UV light, reflection plays a large role in exposure to UV light. The amount of UV light also varies greatly depending on the surface irregularities of the body and skin. The nose, cheeks and lower lip, generally receive the most damaging amounts. The skin has a natural defense mechanism to the UV light. The UV light is scattered Wavelength (nm) 400

500

600 700

Horny Layer Epidermis

Dermis

•^.^P^/ Subcutaneous "o Tissues Fig. 1.15. Skin penetration of different light wavelengths (Herrmann)^^^ Source: Hermann, F. etaL\ Biochemie der Hants, 149, Georg Thieme Verlag, Stuttgart, 1973.

Cosmetics and skin 35 and absorbed by the structure and structural materials of the skin to attenuate the amount reaching the deeper skin layers. Among the components of the skin, melanin produced by the melanocytes in the basal layer shows a very effective UV protective effect. In Caucasians, the amount of melanin is lov^, and there are more cases of skin cancer compared to Japanese with darker skin and other races. This suggests that melanin has a high UV protective function. The amount of UV light that penetrates the skin as a result of these factors varies according to the wavelength. Longer wavelengths penetrate the skin more deeply as shown in Fig. 1.15. 1.6.2. Acute response to ultraviolet light Fig. 1.16 shows the acute changes in skin exposed to UV light. Immediately after bathing in UV light, the skin begins the immediate darkening phase. This immediate darkening is the result of oxidation of pre-existing melanin pigment, but the darkening appears to return to the original color within several hours. This response is initiated by UV-A and visible light. Several hours after exposure to UV light, the skin begins to become red, reaching a peak after 8 and then gradually diminishing. This phase is called sunburn. When exposed to very large amounts of UV light, blisters develop and the skin feels burnt. The wavelength region causing this sunburn is the short wavelength peak in the UV-B band shown in Fig. 1.17. UV light in the 290-300 nm band is 100 times more effective than at 320 nm. When we consider the distribution of wavelengths in sunlight, most sunburn must be caused by the 300-310 nm wavelength band (erythrema production curve). The cells damaged by the UV light produce an inflammatory mediator, expanding the capillaries and resulting in the appearance of sunburn, but further details of the sunburn process are as yet unknown. Anti-inflammatory drugs like aspirin or indomethacin can suppress erythema occurring several hours after UV exposure, suggesting that arachidonic acid metabolism participates in the sunburn process. 3 MED

2 MED

Immediately after exposure (Immediate pigment darkening)

24 hours after exposure (Sunburn)

week after exposure (Sunt an)

Fig. 1.16. Changes in skin exposed to sunlight.

1 MED

36

New cosmetic

science

w ^

250 260 270 280 290 300 310 320 nm Wavelength Fig. 1.17. Erythema curve. A, erythema action spectrum; B, erythema production curve by sunlight (based on erythema curve and spectrum of sunlight).

Approximately 3 days after UV exposure, the skin gradually becomes dark (Fig. 1.16). This delayed darkening, or suntan, is produced by an acceleration of the melanocyte function with the formation of melanin in large amounts and with movement into the keratinocytes. Although this response is initiated after the reddening caused by UVB, large amounts of UV-A have the same effect. Skin that has been suntanned by this mechanism gradually returns to the original color after several months. Simultaneously with this darkening, new skin is regenerated under the damaged skin. The old skin peels off 10-14 days after exposure to the UV light. The acute response to UV light varies among individuals. The minimum erythema dose (MED) is a value used to indicate the acute sensitivity of individuals to UV light. The minimum erythema dose indicates the minimal amount of UV light required to cause redness when a person is bathed in UV light. In other words, individuals with high sensitivity have a low MED since only a small amount of UV light is required to cause skin redness. The erythrema response and darkening also differ with the individual and form a basis for classification of skin type from type I to type VI (Table 1.6). Individuals with type I skin show burns with no tans when first exposed to sunlight for 30Table 1.6. Skin type and sunburn and tanning history Skin Type

Sunburn and Tanning History

I. II. III. IV. V. VI.

Always burns easily \ never tans (sensitive) Always burns easily \ tans minimally (sensitive) Burns moderately ; tans gradually (light brown) (normal) Burns minimally ; always tans well (moderate brown) (normal) Rarely burns ; tans profusely (dark brown) (insensitive) Never burns \ deeply pigmented (insensitive)

Based on first 30 to 45 minutes sun exposure after a winter season of no sun exposure. (Source : Federal Register, 43(166), 38265, 1978)

Cosmetics and skin 37

45 minutes after a winter season of no sun exposure and with no suntan lotion, applied to the skin. Type II skin burns easily but shows minimal tanning. Type III tans always after burning, Type IV skin tans quickly after slight burning, Type V tans with almost no burn, and Type VI tans very rapidly with no burn. Caucasians are usually described as falling in the Type I-IV range. The foregoing describes the response of healthy individuals but some people are oversensitive to UV-B while others are oversensitive to UV-A or visible light which has no acute serious effect on healthy people. These responses are called photosensitivity and the causes are classified into phototoxic response, photoallergy response and photohypersensitivity response. The former responses result from external materials and UV light, while the latter is thought to have various internal causes. In many cases the causes are not clearly known. The phototoxic response can occur in any person applying any one of a number of materials to the skin and then exposing themselves to sunlight. The occasional photoallergy response is related to the immune system response to externally-applied materials and light and generally occurs only in photo-sensitized individuals. Photosensitivity occurs in xeroderma pigmentosum, photoatopia, porphyria, and other conditions such as virally-induced smallpox. 1.6.3. Chronic response to ultraviolet light So-called fisherman's skin and farmer's skin both demonstrate the typical chronic response of skin to UV light. Such skin is dark, feels rough to the touch, and is deeply wrinkled. The nape of the neck, which is constantly exposed to UV light, has characteristic diamond-shaped wrinkles. If this condition worsens, skin cancer may result. Since these types of changes are distinct from natural aging, they are called photoaging or dermatoheliosis. The face is most susceptible to these changes because it is exposed to sunlight throughout the year. It is not clear which wavelength band causes this photoaging, but UV-A, which penetrates deep into the skin as well as UV-B, is believed to contribute to these changes. Since the skin does not show an acute response to UV-A without heavy exposure, UV-A has not been thought to be dangerous. In recent years, however it has been shown that the dangers of UV-A cannot be ignored. Photoaging was first described in Caucasians but it also occurs in the darker skinned races as well and has been clearly confirmed in races living at high altitudes exposed to high UV light levels (Fig. 1.18). People living at high altitudes already show skin wrinkling in their 20s, and the degree is comparable to skin wrinkling in Japanese 4050 year-olds living a normal lifestyle. When these photoaging changes are examined histologically, epidermal thickening and overdeveloped melanocytes are observed. The main components of the dermis are collagen fibers and net-like elastic fibers. Photoaged skin has an abnormal increase in the amount of elastic fibers, and the fine dermal blood capillaries are also dilated. These changes are the opposite of what occurs with true aging changes. It has recently been shown that the immune system is also affected by chronic exposure to UV light. In the future, the effect of UV light on the entire body, and not just the skin, will be clarified.

38 New cosmetic science

Fig. 1.18. Wrinkled skin of high-altitude dweller.

It has recently been reported that application of vitamin A acid to photoaged skin causes the wrinkles to disappear and the skin to return to a youthful condition^^\ 1.6.4. Prevention of exposure to sunshine It is now believed that excess exposure to UV light causes damage to skin and such exposure has almost no benefits. Consequently, the skin should be protected against sunshine to prevent the damage caused by acute and chronic UV exposure. Previously sunscreens were applied to prevent excessive sunburn only during leisure activities. It is now known, however, that dark spots and wrinkles are promoted by chronic UV light exposure, so daily prevention is required. To maintain healthy and beautiful skin, sunscreen should be applied in addition to protective clothing and hats when going out in the sun.

1.7. Aging of skin 1.7.1. Symptoms of aging Like the teeth and eyes, the skin is an organ in which aging changes are easily observed. The degree of change varies greatly between individuals and also depends on the part of the body involved. Table 1.7 lists some of these changes found in dermatological diseases related to aging. However, in addition to these pathological skin changes, a number of other changes occur which detract from the beauty of the skin (Table 1.8). These are called natural or "intrinsic" aging changes to distinguish them from pathological skin changes^^^.

Cosmetics and skin 39 Table 1.7. Dermatological diseases observed in elderly people ' Lentigo senilis ' Leukoderma senile • Verruca senilis ' Angioma senile ' Acrochordon ' Neurofibroma senile (C type nevus) ' Senile comedo ' Senile sebaceous hyperplasia ' Precancerosis (actinic keratosis, cornu cutaneum, Bowen's disease, lentigo maligna) ' Carcinoma cutis (acanthoma, basal cell carcinoma)

L7.2. Instrinsic aging

andphotoaging

The face and nape of the neck as well as back of the hand are frequently exposed to sunlight and become rough and deeply lined. Skin that is continuously exposed to strong sunlight over long periods shows these characteristic changes. Aging signs caused by UV rays are called photoaging. Skin in an elderly person that is unexposed to sunlight, such as the stomach and lower back is quiet different in its internal structure from sunexposed skin in the same person. Generally in intrinsic aging, reduction of many functions and atrophic changes occur in the skin such as reduction of cellular activity and skin thinning. Conversely, photoaged skin is thickened, and there are various symptoms called elastosis that display the presence of massive quantities of thickened, tangled degraded elastic fibers. Table 1.9 shows the characteristic changes in both cases^^'^^^. Both photoaging and intrinsic aging occur in facial skin, but the degree of aging changes that are obvious differs from individual to individual because photoaging is affected by lifestyle, such as the amount of time exposed to sunlight and type of protective daily skin care and intrinsic aging is affected by genetic factors and other internal factors. Table 1.8. Aging signs of skin • Increased wrinkles ' Increased looseness " Reduced gloss, luster, smoothness ' Reduced elasticity • Coarsening of skin texture and random furrows ' Pigmented spots, depigmented spots in some parts of body in some people (The former is called lentigo senilis, the latter is called leucoderma senile.) • Yellowish skin • Thinning of scalp hair and loss of vitality " Reduced scalp hair and body hair ' Increased gray hair ' Lengthening of eyebrow and ear hair ' Coarsening, muddying and bending of nails

40 New cosmetic science Table 1.9. Anatomical differences between intrinsic aging and photoaging "Epidermal Changes> Item

Photoaged Skin

Intrinsic-Aged Skin

Epidermal Thickness

• Thick epidermis

• Thin epidermis

Epidermal Cells (keratinocytes)

• Non-uniform cells • Cells distributed randomly (similar to precancerous condition) • Loss of polarity • Frequent enlargement • Diversified melanosomes (melanosomes lacking cells)

• Uniform cells • Defined cell distribution)

Stratum corneum

• Increased number of cell layers • Diversified form, staining properties and size of corneocytes

• Normal cell layer • Uniform corneocyte size

Melanocytes

• • • • •

• • • • •

Langerhans Cells

Increased cell number Diversified cells Increased melanosome production Marked reduction in cell number Diversified cells

• Polarity maintained • Usually atrophied • Melanosomes uniformly distributed

Cell number reduction Uniform cells Poor melanosome production Slight reduction in cell number Normal cells

(Kligman, A.M. : Aging and Skin, 3. Photoaging of Skin, p.35, Table 2, Seishishoin, 1986) Item

Intrinsic-Aged Skin

Photoaged Skin

Glycosaminoglycans

• Markedly increased

• Slightly decreased

Elastic Tissues

• Tremendous increase • Degenerated into amorphous mass

• Increased but almost normal

Collagen

• Marked decrease of bundles and fibers

• Bundles thick and disoriented

Reticular Dermis Fibroblasts Mast cells Inflammatory cells

• • • •

• • • •

Papillary dermis

• Grenz zone of new collagen (repair zone)

• Non» Grenz zone of new collagen

Capillary vessel

• Small vessels great loss • Abnormal vessels • Telangiectatic

• Moderate loss • Normal • Non-telangiectatic

Lymphatics

• Practically absent

• Moderate loss

Thickened ; Increased and hyperactive Increased Inflammatory cell penetration

Thinner Decreased and inactive Decreased No inflammatory cells

(Kligman, A.M. : Aging and Skin, 3. Photoaging of Skin, p.35, Table 1, Seishishoin, 1986)

1.73. External changes in aged skin 1.7.3.1. Wrinkles Wrinkles occur on almost all parts of the body such as the face, especially the forehead, around the eyes, between the eyes and around the mouth, and on the nape of the neck, elbows, armpits, feet and hands. In most cases, they usually start appearing around age 30 and increase in number, depth and area with aging.

Cosmetics

and skin

41

Fig. 1.19 shows an example of aging changes in wrinkles around the outer corner of the eyes and the results of quantitative analysis using image analysis. Such analysis clearly indicates a marked increase in wrinkles in the late 40s^^'22). Even though we talk about wrinkles as a whole, there are various types of wrinkles, and several classifications have been developed.

a. Aging changes of skin surface configuration at outer corner of eye using direct skin analyzer system.

;c

"

>i I1

/

^

n.sV^ n.s^ 0

10

20

30

40

50

60

70

Age (years) BOX is the number of meshes (obtained by spHtting the binary image into 9 x 9 meshes) where the black pixel ratio is 60% or more and correlates to the amount of wrinkles at the outer corner of the eye. b. Aging changes of skin surface configuration (facial wrinkles) at outer corner of eye. * : p^ •• 1

**** 30

3^ = 0.09A; + 0.07

• • •• •• •• • • •• • 1

70 50 Age (years)

—

90

Fig. 1.20. Aging changes in amount of pigmentation^^\ Source: Arai, K.: J. Soc. Cosmet. Chem. Jpn., 23 (1), 31 (1989).

Cosmetics and skin

43

Mm wmM

....^:

50 30 40 Age (years) a. Depth of Furrows

10

20

10

20

60

--'^4%

70

'2.

CO

o

60 70 50 30 40 50 20 30 40 60 Age (years) Age (years) Regularity of Skin Furrows . Size of Pores Fig. 1.21. Aging changes in surface configuration of cheek skin using replica image analysis^^\ *F < 0.01 (versus 3-9 years), ns., no significant difference, mean value ± SE. Source: Handbook of Dermatology, 1990-B, Skin Surface Image Analysis, Takahashi, p. 17, Nakayama Shoten, 1990.

70

44

New cosmetic science

1.7.3.4. Surface configuration With aging, skin surface relief, which is formed by furrow and ridges, becomes more shallow and also less precise. The direction of the skin furrows becomes irregular, and skin pores tend to become larger (Fig. 1.21)2^'^^). 1.7.4. Aging changes of skin physiological

functions

1.7.4.1. Horny layer (stratum corneum) The most important parameter of horny layer function is the water content which is generally said to decrease with age. Aging changes in the transepidermal water loss (TWL), which is affected by the barrier function of the horny layer, have not been clearly confirmed. In addition, reductions of skin surface lipids and perspiration are a factor in the appearance of dry skin in elderly people^^'^^'^^^ 1.7.4.2. Epidermis Proliferation of epidermal cells is reduced in the epidermis of older individuals. Consequently, the epidermal turnover, or metabolism is reduced. Data regarding epidermal turnover has been obtained without damaging the skin by measuring the size of the corneocytes. As shown in Fig. 1.22, the surface area of the corneocyte of the cheek and forearm increases with age, indicating that the proliferative activity of the epidermal cells (keratinocytes) is reduced. 1.7.4.3. Dermis Just as the proliferative activity of the keratinocytes in the epidermis declines with age, that of the fibroblasts in the dermis also declines with age. Production of collagen, elastin and glycosaminoglycans by the fibroblasts also decline with age. Moreover, since the turnover rate of collagen and other structural proteins is very Cheek

Forearm 1300 h

B 1200 1000

o c . An index of 1 indicates perfectly circular hair, while smaller indexes indicate a change in form from oval to flat.

52 New cosmetic science

Straight hair

Wavy hair

Curly hair

Fig. 2.5. Forms of hair.

Hair Diameter Index

Minor Axis of Hair Major Axis of Hair

The index for Japanese hair is 0.75-0.85 or close to round, while that for negro races is 0.50-0.60, nearer to flat. The characteristics for the different races are shown in Fig. 2.115). Table 2.1. Racial variations in hair diameter index Race Type

Hair Diameter .ndex

Negro Eskimo Tibetan Caucasian Japanese

0.5—0.6 0.77 0.88 0.62-0.72 0.75—0.85

2.2.2. Color of hair Natural hair color varies with race type and there is an entire spectrum of colors ranging from black to dark brown to blonde to red. However, this color spectrum is not due to a variety of pigments, but to just two melanin pigments. In other words, the difference between black and red hair is due to the balance in terms of number and size of eumelanin granules, the true melanin responsible for black pigmentation, and phaeomelanin, a sub-melanin responsible for red pigmentation. This balance determines the actual color of the hair^^). Melanin pigment is produced in the branches of the melanocytes in the upper part of the hair matrix of the hair bulb by the production, oxidation and polymerization of tyrosine, an amino acid^^^. The synthesized melanin granules have a spindle-like form (0.8-1.8 //m long and 0.30.4 //m thick) and they are deposited in the cortex cells of the hair, to move upwards as

Cosmetics and hair and nails

53

Table 2.2. Relationship between hair color and melanin pigments Eumelanin

Hair Color

Phaeomelanin

Blonde Red

Large numbers and size Quite large numbers and medium size Few in number and size Almost none

Gray

Almost none

Black Dark Brown

Almost none Very little Some Large number and size Almost none

the hair grows in length^^^ Table 2.2 shows the relationship between the hair color and the melanin pigments. In people with gray hair, especially race types that normally have black hair, it is very clear that the production of melanin by the melanocytes has completely stopped. This is one phenomenon of the aging process. The graying of hair with age usually starts at the sides of the head, progresses to the top of the head until finally the whole head hair becomes gray. 2.2.3. Structure of a hair shaft Fig. 2.6 shows a longitudinal and transverse section through a hair shaft. Moving from the outside to the center, the hair is divided into three layers; the cuticle, cortex and medulla.

Cortex Cuticle

Medulla

Cortex cell

Fig. 2.6. Structure of hair shaft.

54 New cosmetic science

2.2.3.1. Cuticle The cuticle forms the outer surface of the hair and covers the entire hair from the root to the tip. It has an overlapping scale-like structure and encloses the inner cortex. It is composed of translucent, non-pigmented cells. One cell is about 0.5-1.0/^m thick and about 45 //m long^^); cells of normal healthy hair have about 6-8 overlapping cells in close contact. The cuticle comprises about 10-15% of hair^^^ and has a rough surface composed of hard keratin protein; it is quite susceptible to wear and is easily worn off by excessive brushing or strong shampoo. Fig. 2.7 shows the structure of the cuticle at the microscopic level using transmission electron microscopy^^^ From this figure, it can be seen that the cuticle has a number of overlapping plates. In addition, the cuticle can be divided into three layers from the outermost epicuticle, to the exocuticle to the innermost endocuticle^^^. (1) Epicuticle: the epicuticle is about 100 A thick and contains a large amount of cystine. It has the highest resistance to chemicals that dissolve keratin and protein. However, it is susceptible to mechanical wear. (2) Exocuticle: the exocuticle has a layer called the a-layer which is composed of noncrystalline keratin with abundant cystine. It has strong resistance to chemicals that dissolve proteins but it is weak against agents that can break the cystine bonds. (3) Endocuticle: in comparison to the a-layer, the endocuticle has less cystine and al-

Fig. 2.7. Internal structure of cuticle (TEM x 23,000). CMC, cell membrane complex; Ex, exocuticle; En, endocuticle.

Cosmetics and hair and nails 55

though it is strongly resistant to chemicals that dissolve keratin, it is weak against agents that dissolve protein. As shown in Fig. 2.7, the cuticle cell boundary has a section composed of a central black part enclosed by two white lines on both sides. This is called the cell membrane complex {CMCy^\ As can be seen from Fig. 2.8, the CMC is the point where the two cell membranes of adjoining cuticle cells come into contact. It has a three-layer construction^^); the central black layer is called the d-layer and it has a high electron density and is quite thick (about 100 A). The white lines on either side of the d-layer are called the ^-layer and they are believed to be a simple cell membrane including proteins and lipids. In recent years, the importance of these structures has been re-examined and they are believed to play a role in the adhesion between cuticle cells and between cells in the cortex. They are also believed to be important in preventing the loss of cortical water and protein, as well as in forming a path for the transmission of water and chemical agents such as permanent-wave solutions and hair-coloring agents into the cortex. 2.2.3.2. Cortex The keratinized cortical cells on the inner face of the cuticle are a group of cells aligned along the long axis of the hair in a relatively regular manner. They comprise about 85% to 90% of the hair^9\ The long axis of the cells is about 100//m and the diameter is about

^^''^''^:M \

•W0 MF

CMC t% l > - ^ \

i

I nter MF

material

Fig. 2.8. Internal structure of cortex (TEM x 25,000). CMC, cell membrane complex; MF, macrofibril. Source: Maruyama, T., Kanbe, T., Torii, K.: 31st SCCJ Research Seminar, Oral Presentation, 1991.

56 New cosmetic science

1-6 //m. A residual nucleus can be seen in the center of the cell. The cells include melanin pigment granules determining the hair color, which are seen as black oval or circular bodies in Fig. 2.8. The cortical cells are also very important in the physical and chemical qualities related to smoothness and softness of hair. The cortical cells are composed of numerous bundles of fibrous components called macro fibrils (MF) having a spindle-like form with a diameter of 0.1-0.4//m^^^. Fig. 2.8 shows the microstructure of the cortex cells using a transmission electron micrograph^^). The figure clearly shows the cortical cells with the aligned MF bundles as well as the cell membrane complexes, etc., linking neighboring cortical cells. In addition, the figure shows the intermacrofibrillar material filling the spaces between macrofibrils^^^ 2.2.3.3, Medulla The medulla forms the center of the hair shaft and it is composed of honeycomb-like cells with empty spaces aligned along the longitudinal axis of the hair and including melanin. Thick hair may have thick medulla, the cells may appear like continuous pencil lead or they may be broken in places, or there may be no medulla at all as in vellus hair and infant hair.

2.3. Chemical composition of hair 2.3.1. Chemical composition of hair The major components of hair are proteins. The minor components are melanin pigments, lipids, trace elements, and water. 2.3.1.1. Amino acid composition of hair The principal protein component of hair is cystine-rich keratin. Keratin can be composed of about 18 types of amino acids. Table 2.3 shows the comparative composition of human hair, sheep wool and human epidermis^"^). As shown, a characteristic feature of the amino acid composition of hair keratin is the large amount of cystine. In comparison to sheep wool and human epidermis, human hair has about 40-50% more cystine. The ratio of the basic amino acids histidine:lysine:arginine in human hair is 1:3:10 and this ratio is characteristic^). Human hair has this composition for various reasons but there are structural differences; according to Robbins^^^ men have more cystine and there are differences in the amounts of arginine and methionine according to diet. 2.3.1.2. Melanin pigments The melanin pigments in human hair are reported to form less than 3% of the totaP^^. 2.3.1.3. Trace elements The metallic trace elements in hair include copper, zinc, iron, manganese, calcium, and magnesium, etc.^^^ In addition to these metallic elements, there are also reports of inorganic components such as phosphorus and silicon^^).

Cosmetics and hair and nails 57 Table 2.3. Amino add composition of principal keratin (%) Human Hair Keratin

Sheep Wool Keratin

Human Epidermis

Glycine

4.1-4.2

5.2—6.5

6.0

Alanine

2.8

3.4—4.4

-

Valine

5.5

5.0—5.9

4.2

Leucine

6.4

7.6-8.1

(8.3)

Isoleucine

4.8

3.1-4.5

(6.8)

2.4-3.6

3.4—4.0

2.8

Proline

4.3

5.3-8.1

3.2

Serine

16.5

Amino Acid

Phenylalanine

7.4-10.6

7.2—9.5

Threonine

7.0-8.5

6.6-6.7

3.4

Tyrosine

2.2—3.0

4.0—6.4

3.4-5.7

Asparagine

3.9—7.7

6.4—7.3

(6.4-8.1)

Glutamic acid

13.6—14.2

13.1-16.0

(9.1-15.4)

Arginine

8.9-10.8

9.2-10.6

5.9-11.7

Lysine

1.9—3.1

2.8-3.3

3.1-6.9

Hystidine

0.6—1.2

0.7—1.1

0.6-1.8

Tryptophan

0.4-1.3

1.8-2.1

0.5-1.8

16.6—18.0

11.0—13.7

2.3-3.8

0.7-1.0

0.5-0.7

1.0-2.5

Cystine Methionine

(H.P. Lundgren, W.H. Ward : Ultrastructure of Protein Fibre, Academic Press, N.Y., p.39, 1963)

The total amount of these trace elements determined by ashing is reported as being 0.55-0.94%29). 2.3.1.4. Lipids The lipids in hair vary with the individual but they are reported to form 1% to 9% of the Table 2.4. Internal and external lipids of human hair Lipid Squalene Cholesterol esters and wax esters Monoglycerides Diglycerides Triglycerides Free fatty acids Cholesterol Polarized lipids

Koch^^^

Zahn^^^

External

Internal

9.3% 19.9 3.9 1.8 18.1 45.2 1.8

11.2% 6.4 7.7 5.6 13.3 50.2 5.6

-

-

Internal

-% 1.3

—

0.3 0.3 20.7 0.8 76.6

(J. Koch, K. Aitzermuller, et al. : J. Soc. Cosmet. Chem., 33, 317, 1982) (H. Zahn, S. Hilterhaus-bong : Int. J. Cos. Sci., 11, 167, 1989)

58 New cosmetic science

totaP^^ The lipids obtained from hair are the same as those from the skin; they are classified into lipids (external) that reach the hair via the sebaceous glands of the skin, and lipids that occur internally in the hair. According to the results of Koch et al?^\ typically, there is almost no difference in the composition of the internal and external lipids and the main component is free fatty acids; neutral lipids (wax, glyceride, cholesterol and squalene) have been reported as well. According to Zahn et al?^\ the principal component of the internal lipids is polarized lipids. The comparison of the two sets of results is shown in Table 2.4. Lipids are a field of future growing interest. 2.3.1.5. Water Hair can absorb water and the water content depends on the humidity of the surrounding environment. However, in an atmosphere at 25°C and 65% RH, the water content of hair is usually around 12%-13%. 2.3.2. Chemical bonds in hair The various protein molecules comprising the keratin protein of hair are linked by intermolecular force or bonding. These bonds are believed to maintain the nature and form of hair. Fig. 2.9 shows the active groups and various chemical bonds found in hair^^). 2.3.2.1. Salt linkage (-NHs-OOC-) bond This bond is formed by a mutual electrostatic attraction between the positively-charged Polypeptide chain

Polypeptide chain

NH (Salt linkage)

XH(CH2)2-NH;

NH Lysine residues

(Peptide linkage)

(Disulfide linkage)

Aspartic acid residue

CO

^CH(CH2)2-CO-NH-CH-(CH2)4-NH Lysine residue NH Glutamic acid residue CO \. CO NH CH-CH-S-S-CH-CH I Cystine residue I NH CO

c=o-

I

CHR (Hydrogen bond)

-OOC-CH2-CH

I

-H-

-N CHR

-o=c

N-H-

Fig. 2.9. Chemical bonds in hair. Source: Gershon, S. D. et al.i Cosmetics Science and Technology, 2nd edn., p. 178, Wiley-Interscience, New York, 1972.

Cosmetics and hair and nails 59

ammonium ion of the lysine or arginine residues and the negatively-charged carboxylate ion of the asparagine acid residues. The bond strength is strongest when the pH is in the range of 4.5-5.5 (called the isoelectric point). According to dynamic measurements by Speakman, this type of bonding is responsible for about 35% of the strength of the keratin fibers and it is broken by acid or alkali solutions. 2.3.2.2. Peptide bond (-CO-NH-) The -CO-NH- bond formed between the -COOH of the glutamic acid residues and the -NH2 of the lysine residues when H2O is removed, is the strongest bond. 2.3.2.3. Cystine (-CH2S-SCH2-) disulfide bond This bond is characteristic of proteins containing sulfur; it forms a side chain bond not seen in other fibers and is typical of links with keratin. Currently, it is the basic principle by which a permanent wave is set. The cystine bonds in hair keratin are broken by reducing agents; after the hair has been set to the desired wave, the shape is held by rejoining the broken bonds using oxidizing agents (see item 3.4, Hair Care Cosmetics). 2.3.2.4. Hydrogen bond (C=0'"HN) This bond is formed between amide residues and a nearby carboxyl residue. This bond explains why keratin fibers that have been soaked in water extend more easily than in the dry condition. Conversely, it is well known that when wet hair is curled and then dried, the curls remain in the hair. This phenomenon is called a "water wave".

2.4. Physical characteristics of hair 2.4.1. Extensibility of hair When hair is pulled gradually under a heavy load, it stretches while becoming thinner and then finally breaks when it can extend no more. The extensibility is expressed as the elongation percentage and the load at which the hair breaks is expressed as the tensile strength. The extensibility of hair is measured by stretching a hair of known length at a constant speed in water or under a constant humidity and measuring the load at the break point. The extensibility of hair is not a function of the outer surface but is clearly a function of the hair fiber bundles and is thought to be due to the characteristics of the cortex rather than the cuticle. In other words, the polypeptide chain of the keratin forming the hair fiber bundles is normally in the form of an a-helix but it becomes extended into a zig-zag /3-keratin form; the length of the zig-zag ^-keratin form is about twice that of the a-helix. When the tension is released, the polypeptide chain returns to its normal length^"^) (Fig. 2.10). This can also occur while the hair is extended.

60

New cosmetic science

r I

i

NH

CO

CHR

X®

CO

NH

NH

NH

CHR RHC

Shrinkage/ CHR Water Loss CO

,C0®

OC

CHR

Extension/Water CO Absorption

NH

NH

CHR NH

CO CHR

CO NH

NH CHR

CHR

>

NH CHR /^ /?-form

-form

Fig. 2.10. Transition between a-form and^-form of hair keratin. Source: Elliot, A.: Textile Res. J., 22, 783 (1952).

2.42.

Moisture absorption of hair

When hair is exposed to air, it either absorbs or loses water until it reaches an equilibrium. This equilibrium is affected by the relative humidity. Table 2.5 shows the water content of hair at various relative humidities^^). When the relative humidity is high, the water content of hair also increases. Drooping hairstyles on wet days is due to the breakdown of hydrogen bonds in hair when water absorbed by the hair exceeds a fixed point and the hair returns to the previous style. In addition, brushing on cold dry days generates static electricity and the hairs stick to the brush due to drying out. Hair is very sensitive to changes in humidity; when the moisture content is too high, the hair body and hold is lost and when the level is too low, the hair becomes dry and brittle. Stam et al.^^\ measured the relationship between the changes in the length and diameter of hair and the relative humidity using a microscope and calculated the crosssectional area and the volume from the results (Table 2.6). The results showed that when the relative humidity is high, the length only increases slightly but there is a quite large increase in the diameter. Table 2.5. Water content of hair at various relative humidities Relative Humidity (%) Water Content(%) Temperature : 74 F

29.2

40.3

50.0

65.0

70.3

6.0

7.6

9.8

12.8

13.6

(J.B. Speakman : Nature, 132, 930, 1993)

Cosmetics and hair and nails 61 Table 2.6. Changes in hair diameter and length with relative humidity Absorption RH(%)

0 10 40 60 90 100

Increase in Volume

(%)

Increase in Cross Section Area(%)

0 0.56 1.29 1.53 1.72 1.86

0 4.7 10.5 14.-3 22.3 29.7

0 5.7 12.2 16.3 24.6 32.1

Increase in Diameter

Increase in Length

(%) 0 2.3 5.1 6.9 10.6 13.9

(%)

(R. Stam et al. : Textile Res. J., 22, 448, 1952)

2.5. Hair damage 2.5.L

Condition of hair damage

The hair shaft is the part of the hair protruding from the scalp and it is continually changing according to the age and length of the hair. Additionally, before it is cut, it is subjected to processes such as shampooing, blow drying, brushing, permanent waving, hair coloring and other forms of hair care. It is subject to the greatest environmental stresses including dry atmospheres, UV light, sea water, and swimming-pool chlorine, etc. In particular, the cuticle of the hair shaft is directly affected by these stresses resulting in several cumulative types of damage. Fig. 2.11 shows four examples of the degree of damage sustained by the cuticle. In healthy hair, the edges of the cuticle cells are smooth and the patterns of the cuticle are regular. By contrast, in slightly-damaged hair, part of the cuticle edge is either peeling off or is lost. In damaged hair, the cuticle edge is missing and in some parts, the peeling and loss progresses to another layer. This type of hair has no luster due to random scattering of the reflected light, and the hair does not feel smooth. When the damage has progressed further, in badly-damaged hair, the cuticle is almost completely missing and the cortex is exposed. This type of hair splits and breaks easily. The final result of this accumulated damage is many split and broken hairs (Fig. 2.12). 2.5,2. Hair damage and its causes As a result of damage, hair becomes dry and brittle and loses its body and hold, springiness and lustre; it becomes difficult to style and will not hold a style. The color changes to reddish and there are many split and broken ends. The original beauty of the hair is lost and various problems occur. Table 2.7 summarizes the various reasons for this damage.

62

New cosmetic science

a. Healthy Hair

C. Damaged Hair

b. Slightly-Damaged Hair

d. Badly-Damaged Hair

Fig. 2.11. Degrees of hair damage.

Beauty treatments such as permanent-wave treatments and hair coloring are another chemical cause of hair damage. These chemicals pass through the cell membrane complex (CMC) between the cuticle cells and spread via the CMC of the cortex into the center of the hair. They are known to dissolve part of the CMC20'32), and the proteins inside the hair^^-^^). The cortex plays a role in maintaining the water content of the hair but this function is lost as a result of the dissolution of the CMC and internal proteins. Consequently, damaged hair is very easily affected by changes in environmental humidity causing problems such as dryness and inability to hold a hairstyle.

Cosmetics and hair and nails

63

Furthermore, there are other causes of damage such as UV light and hot air from blow dryers. UV light lowers the tensile strength of hair by generating cysteic acid which breaks the disulfide bonds in hair in the presence of water^^^^\ At the same time, the hair becomes reddish and this is believed to be due to the oxidative breakdown of eumelanin in the hair by the UV light^^^-^^^. Damage and color changes such as reddening are commonly associated with marine and pool sports, but actually, UV light plays the major role in this type of damage which is accelerated by the sea water and pool water. Hair is easily damaged by heat as a result of denaturation of the proteins comprising

Split Hair (xl50)

Magnification of Split Hair (x800)

Broken Hair (x800) Fig. 2.12. Split and broken hair.

64

New cosmetic science

Table 2.7. Causes of damage to hair

• Chemical : Permanent wave, hair coloring, etc. • Environmental : UV light, dry atmosphere, heating with dryer, etc. • Physical : Over-brushing, blow-drying soaking-wet hair

the major part of hair, and excessive use of a hair dryer damages hair. The normal water content of hair is 10-15% but this is reduced through evaporation caused by heating and the hair becomes dry and rough to the touch. At temperatures above 80°C, the hair proteins are denatured and the cuticle is peeled off the hair if it is brushed at the same time as being blow-dried at very high temperatures^^l Caution is required when using a blower for long periods and it is important that the hair is cared for with cosmetic hair treatments before blow drying. Finally, there are physical causes of damage to hair such as over-enthusiastic brushing and blow-drying while the hair is still soaking wet. This always results in loss of the cuticle. Shampooing is a necessary part of daily life, but the friction caused between hairs results in the cuticle peeling off as a result of its inability to withstand wear. Additionally, if the hair is blow-dried while still soaking wet (blown dry while brushing), since the cortex swells with water easily while the cuticle does not, unnecessary force is applied to the cuticle which peels off. Consequently, it is best to towel dry the hair first before blow drying and then to blow dry after the hair is almost dry. The ultrasonic method is a fast way of determining how easily the cuticle is peeled Qff44) Comparison of permanent-waved hair, heat-treated hair, hair exposed to UV light, and untreated hair shows that each of the treatments increases cuticle loss. These results are shown in Table 2.7 which indicates the ease with which cuticle is peeled off in relation to the cause of the damage. From this information, it is clear that after hair treatments such as permanent waving and hair coloring, or after swimming, the hair should be washed in mild shampoo, rinsed and then treated with a hair treatment. 2,5.3. Split hair The final stage of cumulative damage to the hair shaft results in the occurrence of split hairs shown in Fig. 2.12. Hair at this stage has almost no cuticle. Fig. 2.13 shows the changes in the number of cuticle sheets at every 10 cm from the root of a 30-cm hair from a female, observed with a scanning electron microscope. As the micrographs clearly show, at the root, there are 7 overlapping sheets of cuticle cells and there is no difference from healthy hair. However, there is a progressive decrease in the number of sheets at each 10 cm, and at the end of the hair, there is no cuticle. Since hair grows about 1 cm per month (see Section 2.1.1), it is believed that the various physical, chemical and environmental stresses require about 2.5-3 years to completely remove all the cuticle. This type of splitting and cuticle loss to 2 or less sheets of cuticle cells is though to be caused by physical shock including brushing and shampooing.

Cosmetics and hair and nails

Cuticle shee

0 cm Hair Root

7 Sheets

10 cm

4 Sheets

20 cm

1 Sheet

30 cm Hair end

0 Sheets

Fig. 2.13. Hair cuticle loss from root to end in split hair (change in number of cuticle sheets).

65

66

New cosmetic science

2.6. Function and structure of nails 2.(5.7. Function and physiology of nails Nails are a very tough sheet of keratin growing from the epidermis of the dorsal surface of the toes and fingers. They are another form of skin appendage. Nails protect the distal tips of the fingers and toes, enable the fingers to grasp very fine objects, increase the sensitivity of the digits'^^^ as well as increase the strength of the fingers and toes. In addition, the condition of the nails also reflects the health of the body"^^^. In healthy individuals, nails grow by about 0.1-0.15 mm per day'^^^ The growth rate varies with the individual, being faster in children and young people, and slower in older people"^^). The growth rate is also different between toes and fingers, with finger nails growing faster than toe nails'*^^ There are also seasonal growth differences with faster growth in summer and slower growth in winter^^^. 2,6.2. Structure and composition of nails Fig. 2.14 shows the structure of nails"*^^. What is generally called the nail, is actually the nail plate. The nail is equivalent to the horny layer of the skin; it has no living cells, is composed of very tough keratin and is formed of closely-linked sheets of keratin cells. Figs. 2.15 and 2.16 show scanning electron micrographs of the outer surface and crosssection of the nail and the layered structure is clearly evident'^'^).

Nail root Plan

Nail wall Free margin of nail Nail plate

Cross Section-=

Nail bed

Nail matrix Fig. 2.14. Structure of a nail. Source: Higashi, T.: Nails, Nihon Shoseki, 1980.

Cosmetics and hair and nails

67

Fig. 2.15. Scanning electron micrograph of the outer nail surface.

In comparison to the horny layer of the skin, the nail has a lower lipid content of 0.15-0.75%4^\ On the other hand, the sulfur content of 3% is relatively higher than that of the skin keratin^^). Although the form of the nails is different from that of hair, since the proteins from which this is composed are the same, the amino acids in nails are very similar to those of hair in comparison to the horny layer of the epidermis"^^^. Like hair, the nail is produced by the nail matrix. The nail grows out over the nail bed towards the fingertip. (Outer Surface)

;3 CO

Fig. 2.16. Scanning electron micrograph of nail cross-section.

68

New cosmetic science

The nail bed supplies water to the nail and plays a role in ensuring that the nail grows along the nail wall (described below) in a fixed direction. The nail separates from the nail bed at the free margin of the nail and since water is no longer supplied from the bed to the nail at this point, the water content falls, explaining why the free margin of the nail is easily broken^^'^^^. The milky-white half-moon shape at the root of the nail is called the lunula. The nail at this part is not fully keratinized. In comparison to other parts of the nail plate, the lunula is softer and is not in complete contact with the nail bed. The parts of the skin surrounding the nail are called the nail wall. The root of the nail is called the back nail and the sides are called the side nail walls. The skin touching the nail at the root of the nail is called the eponychium; its role is to protect the imperfectly-formed nail. When the eponychium is missing, the nail is often scarred and the newly-formed nail shows abnormalities. The nail matrix contains melanocytes which produce melanin pigment and there are small amounts of melanin in the nail"^^). 2.6.3, Physical characteristics of nails Nails contain from 5% to 24% water depending on the external environment. Like hair, they absorb and lose water quite easily. When nails absorb water, they swell in volume and the thickness changes more than the length and width. This is believed to be the result of the layered construction seen in Fig. 2.16. The change in the toughness caused by water absorption and loss is the same as that of hair becoming softer with water absorption and brittle with water loss. The tendency for nails to break easily is the result of our daily lifestyle such as bathing and washing each day. 2.6.4. Nail damage Nail damage is very common; split nails in which the free margin of the nail looks like mica is called onychoschisis. One cause of split nails at the free margin is the reduced water content due to the inability of the nail bed in this area to supply water to the nail. Another physical cause is excessive use of nail enamel and enamel remover, which cause water and lipid loss, as well as lipid loss due to exposure to soap and detergents. Consequently, when using nail enamel and remover, it is important to choose products that take lipid and water loss from the nail into consideration and to use nail treatments as part of the daily care routine.

References 1. 2. 3. 4.

Noda, H.: Protein Chemistry 4, Structure and Function, (1), p. 763, Kyoritsu Shuppan, 1981. Ogawa, H.: Nishinihon J. Dermatol., 42 (3), 455 (1980). Kobori, T.: Pathology of Hair, p. 107, Bunkodo, 1987. Kobori, T.: Pathology of Hair, p. 15, Bunkodo, 1987.

Cosmetics and hair and nails 69 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50.

Pinkus, H.: The Biology of Hair Growth, p. 15, Academic Press, New York, 1959. Price, M. L., Griffiths, W. A. D.: Clin. Exp. Dermatol., 10, 87 (1985). Pinkus, F.: Jadassohns Handbuch der Haut Geschl. krht, 1/1, p. 239, Springer Verlag, BerUn, 1927. Saitoh, M., Uzuka, M., Sakamoto, M., Kobori, T.: Advances in Biology of Skin, Vol. IX, p. 183, Pergamon Press, Oxford, 1969. Farber, E., Lobitz, W.: Annu. Rev. Physiol., 14, 519 (1952). Auber, L.: Trans. R. Soc. Edinburgh, 62, 191 (1952). Hashimoto, J.: Clin. Dermatol., 27 (1), 15 (1973). Parrakal, P.: J. Ultrastruct Res., 29, 210 (1969). Ito, M., Hashimoto, K.: J. Invest. Dermatol, 79, 392 (1982). Falco, O.-B.: Semin. Dermatol., 4 (1), 40 (1985). Sudo, T.: Diagnosis and Treatment of Hair, p. 11, Bunshodo, 1970. Rock, A., Dauber, R.: Diseases of the Hair and Scalp, 2nd edn., Blackwell Scientific Oxford, 1991. Prota, G., Thompson, R. H.: Endeavour, 35, 32 (1976). Montagna, W., Parakkal, P.: The Structure and Function of Skin, 3rd. edn.. Academic Press, New York, 1974. Mercer, E. H.: Keratin and Keratinization, p. 266, Pergamon Press, Oxford, 1961. Maruyama, T., Kanbe, T., Torii, K.: 31st SCCJ Research Seminar, Oral Presentation, 1991. Leon, N. H.: J. Soc. Cosmet. Chemists, 23, 427 (1972). Swift, J. A., Bews, B.: J. Soc. Cosmet. Chemists, 25, 355 (1974). Swift, J. A., Holmes, A. W.: Textile Res. J., 35, 1014 (1965). Lundgren, H. P., Hard, W. H.: Ultrastructure of Protein Fibre, p. 39. Academic Press, New York, 1963. Robbins, C. R.: Text. Res. J., 891 (1970). Menkart, J., Wolfram, L. J., Mao, I.: J. Soc. Cosmet. Chem., 17, 769 (1966). Bate, L. C. et al:. New Zealand J. Sci., 9 (3), 559 (1966). Goldbulm, R., Derby, S.: J. Invest. Dermatol., 20, 13 (1953). Dutcher, T. F., Rothman, S.: J. Invest. Dermatol., 17, 65 (1951). Nicolaides, N., Foster, R. C : J. Am. Oil Chem. Soc, 33, 404 (1956). Koch, J., Aitzetmuller, K. et al: J. Soc. Cosmet. Chem., 33, 317 (1982). Zahn, H., Hilterhaus-bong, S.: Int. J. Cosmet. Sci., 11, 167 (1989). Gershon, S. D. et al: Cosmetics Science and Technology, p. 178, Wiley-Interscience, New York, 1972. Elliot, A.: Textile Res. J., 22, 783 (1952). Speakman, J. B.: Nature, 132, 930 (1933). Stam, R. et al: Textile Res. J., 22, 448 (1952). Baba, N., Nakayama, Y., Nozaki, F., Tamura, T.: J. Hygienic Chem., 19, 47 (1973). Oku, M., Nishimura, H., Kanehisa, H.: J. Soc. Cosmet. Chem. Jpn., 21 (3), 204 (1987). Kanedaka, S., Miyata, M., Nakamura, Y.: J. Soc. Cosmet. Chem. Jpn., 24 (1), 5 (1990). Beyak, R. et al: J. Soc. Cosmet. Chem., 22, 667 (1971). Robbins, C , Kelly, C : Textile Res. J., 40, 891 (1970). Tatsuda, M., Uemura, M., Torii, K., Matsuoka, M.: J. Soc. Cosmet. Chem. Jpn., 21 (1), 43 (1987). Chedekel, M. R., Post, P. W., Deibei, R. M., Kalus, M.: Photochem. Photobiol., 26, 651 (1977). Kanbe, T., Fukuchi, Y., Uemura, M., Torii, K.: JCSS 14th Scientific Seminar (1989). Higashi, T.: Nails, Nihon Shoseki, 1980. Higashi, T.: Fragrance J., 79, 12 (1986). Yamazaki, I., Tanaka, M., J. Soc. Cosmet. Chem. Jpn., 25 (1), 33 (1991). Yasuda, T.: Fragrance J., 79, 12 (1986). Baden ,H. P.: Biochem. Biophys. Acta, 322, 269 (1973). Nishiyama, S.: Fragrance J., 79, 4 (1986).

3 Color and cosmetic color materials There is a close relationship between cosmetics and color. The search for beauty is a basic human instinct. Makeup cosmetics beautify the appearance by changing the color of the skin. In addition, color can enhance the appeal of cosmetic products which rely on color for image. The rapid developments in the science of color and in instruments for measuring color have made color management much easier, and are now utilized in the design manufacturing and marketing of cosmetics. Year-by-year, the regulations governing the materials used to give cosmetics their color become stricter and stricter from the safety aspect and, in each country, the use of organic color materials in cosmetics is regulated by law with regard to product quality and scope of usage. Powder materials such as inorganic pigments and extender pigments may only be used if they meet the standards of different countries for heavy metals and other impurities or are those which have received the approval of the regulatory authorities. The technical expertise and knowledge of color scientists handling the basic constituents of cosmetics as well as accurate information related to coloring materials used in cosmetics is absolutely essential to this. Additionally, the laws related to coloring materials differ according to national legislation making it necessary to exercise caution when exporting cosmetics.

3.1. Color 3.1.1. Light and color Light enters the eyes when they are open except when there is no light. The component of light that can be seen by the eyes is called visible light. The wavelengths longer than visible light are the infra-red wavelengths and the wavelengths shorter than the visible band are the ultra-violet wavelengths. The wavelength of visible light is in the band 400760 nm (Fig. 3.1). Natural sunlight contains many of the visible wavelengths but it is perceived by the human eye as colorless. However, when sunlight is passed through a prism, it is split into six basic colors: red, orange, yellow, green, blue, and violet. Color is an expression of the different energy levels in light but it is not in itself a property of light. The light wavelengths are sensed by the visual receptors in the eye and the stimulation caused by each wavelength is expressed as color. In other words, color can be described as a sense. 70

Color and cosmetic color materials

71

Visible light -

Ultraviolet light

^

tj o

QJ ;3

>

cCT3

>^

O

CQ

400

Infrared

QJ

QJ CD

500

-a cu

O

1

Cr:::

600

700 wave length (nm)

Fig. 3.1. Wavelength and color.

3,1.2. Color perception Color perception differs greatly in different animals. In this book, we are only describing the human perception of color. The structure of the human eyeball resembles that of a camera. The crystalline lens has a variable focal length and is able to focus the image of an object on the retina. The iris in front of the lens functions like the aperture of a camera. The retina is composed of two types of visual receptors: rods, and cones. The rods function at low light levels and their main role is to sense the intensity of the light, whereas the cones function at high light levels and their role is to sense color. The dashed line in Fig. 3.2 shows the sensitivity of rods which is greatest around 511 nm (wavelength equivalent to yellowish-green). By contrast, the solid line shows the sensitivity of the cones which is greatest at 554 nm (wavelength equivalent to greenish yellow^). In addition, the cones have three types of receptors for blue, green and red. The light absorbed by the rods and cones composing the receptors in the eye is converted to electrical signals which are transferred to the brain via the horizontal cells, optic nerves and spinal cord, where they are interpreted as color and brightness.

>. "5o

1.0

\/

0.8

/ /

0.4



0.2

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/

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400

/

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/ / y

r-

/^-^

A \ /

//

m 0.6 J

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Rod

,

1 \

X\

\

\ \ \

, V

500 600 Wavelength (nm)

\ \ \

X 700

Fig. 3.2. Spectral response curve of scotopic vision (dashed line) and photopic vision (solid line).

72 New cosmetic science

500 600 wave length (mm)

700

Fig. 3.3. Spectral reflection curve, red: Lake red CAB; yellow: Hanza yellow; blue: Phthalocyanine blue.

3,13,

Color of coloring materials

The color of materials varies according to its composition and the type of light striking it. The same material will appear to be a different color in sunlight, fluorescent lamp and incandescent lamp. Light striking an object is either reflected off the surface of the object, back from the object interior, absorbed by the object or passed through the object. When white light strikes a colored object, the wavelength of light observed as the color is reflected and other parts are absorbed. The spectral reflection curve (Fig. 3.3) shows the reflected components of light at each wavelength in comparison with a standard object (white). The form of this curve predicts which color the object will appear. Similarly, the spectral transmission curve shows approximately which wavelengths are transmitted when white light strikes an object that transmits light. Coloring materials are chemical substances that absorb or transmit specific wavelengths. Red pigments reflect red light and absorb light other than red. In addition, red dyes absorb light other than red and transmit red light. 3.1.4, Three attributes of color Color can be classified as either (1) achromatic, or colors such as white, gray, and black which neither absorb nor reflect the components of light, and (2) chromatic, or colors with hue. Chromatic colors have color as a result of absorbing part of the illuminating light or reflecting or transmitting the light in the visible light region. Color is composed of three elements: hue, value and chroma, called the three attributes of color. (1) Hue: Colors such as red, yellow, green, blue and violet demonstrate this quality which is determined by wavelength.

Color and cosmetic color materials

73

White

Green

Chroma

Yellow

Black Fig. 3.4. Three-dimensional color space showing three attributes of color.

(2)

Value: The value is measured on a scale which evaluates whether the reflection from the surface of the object is high or low. When the value is high, the color is bright, and when it is low, the color is dark. (3) Chroma: Chroma expresses the degree of brilliance of color. A brilliant color has a high chroma value and a dull color has a low chroma value. A diagrammatic representation of hue, value and chroma on three axes is called a three-dimensional color space (Fig. 3.4) and any color can be represented in spatial terms within this color space. 3.1.5. Expression of color The human eye is able to recognize several million colors based on slight differences in the value, hue and chroma. When talking about a specific color or when recording a color, we need to be able to define that color exactly. The most accurate way is to have an actual color sample, but even in this case, there is the problem of aging-associated color changes. Ignoring color samples, for any product, it is of importance to be able to manufacture with identical color and there is a need for a systematic method of recording color as a numeric value and classifying it. 3.1.5.1. Color naming methods Trivial names: this is a system of naming colors such as salmon pink, emerald green, and lavender purple created by people who deal with colors frequently. It is called the trivial naming system. A feature of the system is that it is very similar to the original sense of color possessed by people but unless you are a specialist, it is very difficult to get an ex-

74 New cosmetic science

act impression of what color is meant. The system is influenced by the individual variation in people's color sense. General color names: general color names such as red, yellowish-red, yellow, yellowish green, green, bluish green, blue, bluish violet, violet, reddish violet are adjective modifiers related to the value and chroma of color and when used with words such as light, dark, heavy, bright, etc., they can be useful in giving a more detailed impression of color. This object color naming system is described in the Japan Industrial Standards^^ 3.1.5.2. Color systems Munsell color system: the Munsell color system is a system expressing colors in terms of hue, value and chroma. It is a system in widespread use today as it is very similar to the human color sense. In Japan, the Munsell color system has been published by the Japan Standard Association as the JIS Reference Colors^^ As shown in Fig. 3.5, hue is linked in a circle of five principal colors: red (R), yellow (Y), green (G), blue (B) and purple (P) with the addition of five intermediate colors: yellowish-red (YR), greenish-yellow (GR), bluish-green (BG), bluish-purple (BP) and reddish-purple (PR). These ten hues are divided into 10 equal parts in sensory terms and the representative hues are arranged at the 5 positions. This type of circle of colors is called a hue circle. The value is also split into 10 equal parts in sensory terms with the achromatic colors black equal to 0, and white equal to 10. Chroma is assigned sequential values 1, 2, 3,... in sensory terms with achromatic colors being 0. The Munsell color system uses this type of arrangement to express any color in terms of HV/C. For example, 5R4/14 expresses the highest saturation of red. CIE standard colorimetric system: in 1931, the Commission Internationale del'Eclariage established an international system of expressing colors using tristimulus values: X, Y, and Z. In Japan, the XYZ system of describing colors is also incorporated in the JIS^). The CIE chromaticity diagram has two axes, x and y, at a right angle on which the spectral at each wavelength is plotted showing the spectral curve and these are joined up to obtain the spectral locus (Fig. 3.6). The chroma axis is found from the following equations. x = X/{X+Y-\-Z),

y=Y/(X+Y+Z),

z = Z/(X+Y + Z)

Since x + >^ + z = 1, the chromaticity can be expressed just by x and y. The projection of the line linking the achromatic point (W) and the chromatic point (50 in the chromaticity diagram (Fig. 3.6) indicates the principal wavelength Xd at the point (^2) where it intersects the spectral curve; the distance from W is the color "purity" (same meaning as chroma). Moreover, since Yis equivalent to value, 7, x, y expresses the color. Hunter Lab system^): in 1948, R. S. Hunter proposed a color system with the ability to distinguish colors based on human senses. In this system, the tristimulus values X, Y, and Z are converted to the equivalent L, a, and b values using the following formulae.

Color and cosmetic color materials

75

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Chroma — -^ Fig. 3.5. Munsell Color System (Japan Standards Association, JIS Reference of Color Committee) JIS.

76 New cosmetic science

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CH3

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Molecular Formula and Weight 136.24

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The sterols and higher alcohol components are mainly cholesterol, and isocholesterol but also include C13 to C33 higher alcohols. Lanolin has an affinity for skin and is quite sticky as well as being physically hygroscopic so it is used in creams and lipsticks. 5.1.3.

Hydrocarbons

Hydrocarbons used as raw materials in cosmetics are normally saturated and have carbon chains longer than C15. In the main, they are liquid paraffins, solid paraffins and petrolatum obtained from petrochemical resources, as well as squalane obtained by hydrogenating squalene obtained from both animals and plants. 5.1.3.1. Liquid parajfins Liquid paraffins are manufactured by removing solid paraffins from the petroleum fraction obtained above 300°C. They are a complex mixture of saturated hydrocarbons with 15-30 carbons and are liquid at room temperature. They are easily manufactured and are colorless, and odorless. They are chemically inactive and form emulsions easily. They are used in skin care cosmetics such as creams and milky lotions and to control moisture loss from the skin and improve the feeling on use. 5.1.3.2. Paraffin Paraffin is a colorless or white translucent solid (melting point 50-70°C) obtained either by vacuum distillation or solvent extraction of the final fraction remaining in petroleum distillation. It is composed mainly of straight hydrocarbon chains but commonly includes 2-3% branched hydrocarbons. The carbon number ranges from C16-C40 with C20C30 being most common.

Raw materials of cosmetics

125

Like liquid paraffins, paraffin is colorless, odorless and chemically inactive and is used widely in creams and lipsticks, etc. 5.1.3.3. Petrolatum The light grease obtained when waxes are removed by solvent extraction from the fraction remaining after vacuum distillation of petroleum is called petrolatum or vaseline. The main component is C24-C34 hydrocarbons in a noncrystalline form. Petrolatum is not a simple mixture of liquid paraffins and paraffin; it is believed to be a colloid composed of external phase solid paraffin and internal phase liquid paraffins. Like liquid paraffin, petrolatum is odorless, chemically inactive and has high adhesive power so it is used widely in creams and lipsticks, etc. 5.1.3.4. Ceresin Ceresin is refined ozocerite and it is mainly composed of C29-C35 straight hydrocarbons although it sometimes includes isoparaffin. The molecular weight is higher than that of paraffin and the specific gravity, hardness and melting point (61-95°C), etc., are high. It is used as a hardening agent in lipsticks, hair sticks, etc. 5.7.5.5. Microcrystalline wax Microcrystalline wax^^ is a solid obtained by extracting the oil from petrolatum. It is a complex mixture composed mainly of C31-C70 isoparaffins. It has a microcrystalline structure, high adhesive power, good extensibility, is not susceptible to low temperatures, and a high melting point (60-85°C). When mixed with other waxes, it suppresses crystal formation making it useful in lipsticks and creams. 5.1.3.6. Squalane Squalene occurs in large amounts in various species of deep sea sharks and it is also found in olive oil, etc. Squalane (2,6,10,15,19,23-hexamethyltetracosan, C30H62) is obtained by hydrogenating squalene; it is liquid at room temperature. Squalane is a very safe, chemically inactive oil used widely in skin care cosmetics such as creams and milky lotions, etc. 5.1.4. Higher fatty acids Fatty acids are compounds with the general chemical formula RCOOH where R is either a saturated alkyl group or an unsaturated alkenyl group. They include various esters in natural fats and oils. Fatty acids in various plant and animal fats have many straight chain carbon molecules and are almost all even numbered. However, progress in petrochemical synthesis has led to the development of side chain and odd number fatty acids8). Fatty acids are mixed with fats and oils, waxes and hydrocarbon compounds for use as raw materials of cosmetics. They are also used with caustic potash and triethanolamines, etc., as emulsifiers for the production of soaps. 5.1.4.1. Laurie acid: CHs(CH2)ioCOOH Laurie acid is obtained by distillation of the fatty acid mixture obtained by saponifica-

126 New cosmetic science

tion of coconut and palm nut oils. Soap obtained by mixing lauric acid with sodium hydroxide and triethanolamine has high solubility in water and lathering qualities making it useful for cosmetic soaps and cleansing preparations. 5.1.4.2. Myristicacid: CHs(CH2)i2COOH Myristic acid is obtained by distillation of the fatty acid mixture obtained by saponification of palm nut oil. It is not used directly to any great extent in cosmetics but myristic acid soap has excellent lathering qualities and cleansing power so it is used in cleansing preparations. 5.1.4.3. Palmitic acid: CHi(CH2)i4COOH Palmitic acid is obtained by saponification of palm oil, etc. It is used as a oily base in creams and milky lotions, etc. 5.1.4.4. Stearic acid: CH3(CH2)i6COOH There are two manufacturing processes for stearic acid: (1) production by removing liquid acids (mainly oleic acid) from the fatty acids obtained by saponification of fat from beef tallow, and (2) production by distillation of fatty acids obtained by saponification of hydrogenated soy bean or cotton seed oil. Stearic acid obtained by the former method contains quite a lot of palmitic acid, whereas the latter method produces stearic acid of high purity and high melting point^^. Stearic acid is used in creams to modify the cream consistency and hardness; it is common in creams, lotions and lipsticks, etc. 5.1.4.5. Isostearic acid The Cig saturated fatty acid with a branched structure is called isostearic acid. Isostearic acid is formed by hydrogenation of the unsaturated fatty acid byproduct when synthesizing dimer acid from oleic acid^\ It can also be produced by the Guerbet method and by hydrogenating and oxidizing the aldol condensate of nonyl aldehyde. Isostearic acid is a liquid ingredient with a lower melting point than saturated fatty acids like stearic acid and palmitic acid and it is less easily oxidized than unsaturated fatty acids such as oleic acid. It is used as an oily raw material and the salts such as triethanolamine are used as emulsifiers. 5.7.5. Higher alcohols Higher alcohol is the name given to monovalent alcohols with six or more carbon atoms. They are broadly grouped into alcohols produced from natural oils and fats and alcohols produced from petrochemicals^^^ The higher alcohols are used both as oily raw materials and as emulsion stabilizers in emulsified products. 5.7.5.7. Cetyl alcohol^^\' CHs(CH2)i50H Cetyl alcohol is also called cetanol and it is produced by fractional distillation of the alcohols obtained by saponification of whale oil. It can also be produced by fractional distillation after reduction of fat from beef tallow, as well as by the Ziegler reaction.

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Cetyl alcohol is a white waxy solid with a hydroxyl group so it does not have emulsifying properties itself but is used as an emulsion stabilizer in emulsified products such as creams and milky lotions. 5.7.5.2. Stearyl alcohol: CH3(CH2)i70H Stearyl alcohol is manufactured by the same method as cetyl alcohol. It is a white waxy solid. It is used both as an emulsion stabilizer in emulsified products such as creams and milky lotions, and in stick products such as lipsticks. 5.1.5.3. Isostearyl alcohol Isostearyl alcohol is the name given to the Cig saturated alcohol with a branched structure. It is obtained by chemical synthesis using the Guerbet reaction, the oxo reaction and by aldol condensation, etc. In recent years, isostearyl alcohol produced by reduction of isostearic acid formed by hydrogenation of unsaturated fatty acid byproducts of dimer acid production has appeared on the market. Isostearyl alcohol is a liquid ingredient with excellent heat and oxidation stability; it is used as an oily raw material. 5.1.5.4. 2-Octyl dodecanol 2-Octyl dodecanol is synthesized by the Guerbet reaction and by aldol condensation. It is a colorless transparent liquid with almost no smell and a low freezing point due to its branched structure which is unusual in higher alcohols. It has good feeling on use so it is used as an oily raw material. 5.1,6. Esters Esters are obtained by dehydration of acids and alcohols. Typical acids are fatty acids, polybasic acids, and hydroxy acids; typical alcohols are lower and higher alcohols, and polyhydric alcohols. Various esters are produced from different combinations of acids and alcohols but relatively few are used in cosmetics. Esters have different properties depending on the structure, molecular weight, etc., and they are used as emollients, dye solvents and clouding agents, etc. 5.1.6.1. Isopropyl myristate Isopropyl myristate is a colorless transparent liquid produced by esterification of myristic acid and isopropanol under sulfuric acids followed by distillation and deodorization. It is used as a miscible agent for oil and water mixtures, as a solvent for dyes, etc., and in milky lotions, makeup products and hair cosmetics. 5.1.6.2. 2-Octyldodecyl myristate 2-Octyldodecyl myristate is an ester of myristic acid and 2-octyldodecanol obtained by the Guerbet reaction. It has a low melting point and is very resistant to hydrolysis. It is used to control moisture loss from the skin as well as to improve the feeling on use.

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5.1.6.3. Cetyl 2-ethyl hexanoate Cetyl 2-ethyl hexanoate is an ester of cetanol and 2-ethylhexanoic acid. It has a low viscosity and high resistance to hydrolysis and oxidation, as well as a good feeling on use so, it is used widely in creams, milky lotions, etc. 5.1.6.4. Di-isostearyl malate Di-isostearyl malate is an ester of isostearyl alcohol and malic acid. It is a thick transparent liquid in spite of its high molecular weight. The isostearyl alcohol used in this production is composed mainly of 5,7,7-trimethyl-2-(l,3,3-trimethylbutyl) octyl alcohol. Di-isostearyl malate is very resistant to hydrolysis and oxidation. It has a relatively low stickiness in spite of its high viscosity. It is excellent as a dispersant and miscible agent for pigments, and also as a miscibilizer for polarized-nonpolarized oily mixtures such as castor oil and liquid paraffin. As a result of these characteristics it is used in stick products such as lipstick, as well as in foundations and creams. 5.7.7.

Silicones

Silicones is the name given to organic silicon compounds containing the siloxane chain (-Si-O-Si-). A typical example is methylpolysiloxane in which all the organic groups are methyl groups. The silicones are available in a wide range of viscosities. Silicones are highly hygroscopic and they have none of the sticky feeling found in hydrocarbons so they have good feeling on use making them suitable for a wide range of applications on skin and hair. Two typical silicones are described below.^^-^^^ 5.1.7.1. Dimethylpolysiloxane

CH3

I-

CHa-Si-O

I

CH3

CH3

I -Si-0 I CHa

CH3

I

-Si-CHa

I

CH3

Dimethylpolysiloxane is a colorless transparent oil. There are low-viscosity oils and pastes depending on molecular weight. Since the solubility of other materials worsens with increasing molecular weight, such low-viscosity materials have many applications. The high hygroscopy makes dimethylpolysiloxane useful in skin cosmetics for resisting fade of make up caused by water and perspiration. Dimethylpolysiloxane reduces the stickiness of oils giving a light feeling on use; it is also employed in a wide range of skin and hair products due to its spreadability. 5.1.7.2. Methylphenylpolysiloxane Methylphenylpolysiloxane has a structure in which some of the methyl groups of dimethylpolysiloxane are replaced by phenyl groups. It is characterized by complete insolubility in ethanol. However, it has good compatibility in other oils and is used in a wide range of products.

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5.7.8. Others Polyoxypropylene adducts of the lower alcohols like butanol are used in liquid hair dressings. The adducts are obtained by addition of propylene oxide to lower alcohols with an alkaline catalyst such as sodium hydroxide. Comparatively low molecular weight adducts are soluble in ethanol and liquid at room temperature. They are used in liquid hair dressings due to their ability to keep hair neat and tidy.

5.2. Surface active agents The solute in a solution can be adsorped to a gas-liquid, liquid-liquid, or liquid-solid surface; these remarkable changes in the properties of surfaces are called surface activity and so-called surface active agents are materials demonstrating unusual surface activity. This surface activity is exploited in emulsification, solubilization, permeation, wetting, dispersion, cleansing, as well as in moisturizing, sterilization, lubrication, electrostatic prevention, softening, antifoaming, etc. There are a very large number of surface active agents but they share a similar molecular structure; the molecule has a part with an affinity for oils (lipophilic or hydrophobic) and a part that has an affinity for water (hydrophilic). The combination and balance of these causes various changes in the properties of the interface or surface. Surface active agents (surfactants) are classified in various ways according to chemical structure, synthesis method, properties and uses, etc. However, generally the major classification is based on the ionic dissociation when dissolved in water. Dissociating types are classified as anionic, cationic and amphoteric types, whereas non-dissociating types are classified as non-ionic. The following section describes some typical surfactants based on this classification as well as some polymeric and natural surfactants. 5.2.1. Anionic

surfactants

When anionic surfactants are dissolved in the water, the hydrophilic base dissociates into anions; anionic surfactants are classified broadly into carbonate, sulfate ester, sulfonate and phosphate ester types. Generally, a soluble salt such as sodium, potassium, or triethanolamine is used as the hydrophilic part. A great many compounds can be used as the lipophilic part but generally alkyl or branched alkyl groups are used. Consequently, the molecular structure incorporates acid-amide bonds, ester bonds and ether bonds, etc. Typical anionic surfactants are described below. 5.2.7.7. Soap: RCOOM [R: Cy_2i> M: Na, K, N(CH2CH20H)s] Soaps are obtained by hot saponification of an alkaline aqueous solution of fats such as tallow fats, coconut oil and palm nut oil; the reaction between higher fatty acids and alkali creates a so-called neutral soap. Soaps are widely used in cosmetics as cleansing creams and shaving creams due to their excellent cleansing and lathering properties.

130 New cosmetic science

5.2.1.2. Alkyl sulfate: ROSOjM Alkyl sulfates are obtained by reacting fatty alcohols with chlorosulfonic acid, sulfuric anhydride, or fuming sulfuric acid, etc. and then neutralizing. They are used in such cosmetic products as shampoos and dentifrices due to their excellent cleansing and lathering properties. 5.2.1.3. Polyoxyethylene alkyl ether sulfate: RO(CH2CH20)^SOsM Polyoxyethylene alkyl ether sulfate is obtained by polymerizing oxyethylene and a fattyacid alcohol by addition polymerization followed by sulfonation and neutralizing with an alkali. The solubility is good and it is used widely in shampoos, etc., due to its excellent cleansing and lathering properties. The alkyl group is C12-C14 and two or three moles of oxyethylene give improved lathering and cleansing. 5.2.1.4. Acyl N-methyl taurate R • CONCH2CH2SO3M

I

CH3

Acyl A^-methyl taurate is obtained by a dehydrochloric acid reaction under alkaline conditions of an acyl chloride and methyl tauric acid, or by a dehydration reaction between a fatty acid and methyl tauric acid. It is very safe and usable in wide pH range and in hard water as well as good lathering properties so it is widely used in cosmetic cleansing creams, shampoos, etc. 5.2.1.5. Alkylether phosphate KOxp^O

RO^^^O

RO^^^O

MO"" ^OM

RO"" ^OM

RO^ ^ OR

Monoalkyl ether phosphate Dialkyl ether phosphate

Trialkyl ether phosphate

Alkylether phosphate is obtained by phosphoric esterification of a fatty alcohol or the terminal group of the polyoxyethylene derivative and then subsequent neutralization. The product on the market is actually a mixture of the mono-, di- and trialkyl ether phosphate. The monoalkyl ether phosphate is soluble in water but the trialkyl ether phosphate is only slightly soluble so this surfactant must be selected according to product usage. Alkylether phosphate is used in cosmetic cleansing creams and shampoos. 5.2.1.6. N-Acylamino acid salts Since amino acids have both amino and carboxyl groups in the molecule, it is possible to obtain surface activity by introducing a lipophilic material. A typical substance is A''acylamino acid salt which is obtained from a reaction with a fatty acid. Examples are NAcylsarcosinate RCON(CH3)CH2COOM, A^-acyl-A^-methyl-/?-alaninate RCONCCHg)CH2CH2COOM, and A^-Acylglutamate RCONHCH(COOM)CH2CH2COOM.

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131

Since A^-acylglutamate has two carboxyl groups in the molecule, it is possible to obtain surfactants containing mono- or di- salt with any ratio. This A^-acylglutamate is used in shampoos, cleansing creams and dentifrices. 5.2.2. Cationic

surfactants

When a cationic surfactant is dissolved in water, the hydrophilic part dissociates as cations. Since this is the reverse of anionic surfactants, these materials are called invert soaps. Cationic surfactants have normal surface activities such as cleansing, emulsification and solubilizing, but they are especially well adsorbed onto smooth hair and also have anti-static properties, so they are used in hair treatments. Cationic surfactants are classified from their structure into quaternary ammonium salts and amine derivatives but the amine derivatives are hardly used in cosmetics and are omitted from this discussion. 5.2.2.7. Alkyltrimethyl ammonium chloride: (RN-^(CHj)j)Cl~ R: Cj^C22 Alkyltrimethyl ammonium chloride is obtained as the quaternary ammonium salt via the alkyldimethyl amine produced by reacting an alkyl amine with methyl chloride in an alkaline medium under pressure. 5.2.2.2. Dialkyl dimethyl ammonium chloride: (R'R'N^(CHj)2)Cl~ R: Ci^C22 This compound is known to have smoothing properties on tangled hair and also has antistatic properties, so it is used in hair rinses. It has poor bactericidal activities but low toxicity and skin irritability. 5.2.2.3. Benzalkonium chloride CH3

^

^CH-N^-R

ci-

CR:C.3~M]

CH3

This compound is well known as an invert soap and it is generally used as a bactericide particularly in shampoos, hair tonics and hair rinses. 5.2.3. Amphoteric

surfactants

Amphoteric surfactants have both cationic and anionic functional groups coexisting in the molecule. Generally, under alkaline conditions, they dissociate into anions, and under acid conditions, into cations. For this reason, they can be used to make up for the deficiencies of ionic surfactants. In comparison to ionic surfactants, they have very low skin irritability and toxicity and many amphoteric surfactants have good cleansing, bactericidal, bacteriostatic, lathering, and softening properties. These properties are used to advantage in shampoos and baby products; in addition, they are used in aerosols due to their ability to stabilize the lather and promote its formation.

132 New cosmetic science 5.2.3J. Alkyl dimethylaminoacetic acid betaine: RN^(CHj)2CH2COO- R: Cj2-C]8 As shown by the above structure, the surface activity of this compound is due to the combination of a cationic quaternary ammonium salt and an anionic carboxyl group. A characteristic feature of alkyl dimethylaminoacetic acid betaine is its good solubilization ability and stability across a wide pH range. In cosmetics, it is used in shampoos and hair rinses due to its softening, anti-static and wetting properties. 5.2.3.2. Alkyl amidopropyl dimethylaminoacetic acid betaine: RCOONH(CH2)3N^. (CHs)2CH2COOThis compound is also used in shampoos, etc., due to its softening, anti-static and wetting properties. 5.2.3.3. 2-Alkyl-N-carboxymethyl'N-hydroxyethylimidazolinium betaine R-cr^

I

^N^-CH2

/ \

-OCOCH2

CH2CH2OH

The above structural diagram shows that this compound has an imidazolin ring and it has recently been elucidated that the ring is open rather than closed^^^ Like other amphoteric surfactants, this compound has very low toxicity, skin irritability and mucous-membrane irritability and also makes the hair softer and more glossy. In addition, it is able to tolerate hard water, making it ideal for use in hair cosmetics, creams and emulsions, etc. 5.2.4. Non-ionic

surfactants

Non-ionic surfactants are unlike ionic and amphoteric surfactants because they do not dissociate into ions. Their surface activity is due to the presence of -OH, - 0 - , -CONH-, and -COOR groups in the molecule. Owing to this structure, they are generally classified into polyoxyethylene chains having hydrophilic groups, and compounds with hydroxyl groups. In other words, the lipophilic groups are broadly the same as the ionic surfactants, but there are many possible combinations of types ranging from those with low water solubility, due to the length of the polyoxyethylene chain containing the hydrophilic groups, to those with good water solubility due to the number of hydroxyl groups. These combinations cause large differences in properties such as degree of solubility, wetting, penetration power, emulsification and solubilization, etc., of nonionic surfactants due to the different balances (HLB) of lipophilic and hydrophilic groups. 5.2.4.1. Polyoxyethylene type non-ionic surfactants RO(CH2CH20)„H RCOO(CH2CH20)„H RC6H60(CH2CH20)„H

R: C12-C24 R: C12-C18 R: C8-C9

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133

As the formulae show, these compounds are obtained by addition polymerization of ethylene oxide at normal or elevated pressures in an alkaline medium. The lipophilic groups are typically a higher fatty alcohol, a higher fatty acid, an alkyl phenyl, an alkylolamide or a sorbitan higher fatty-acid ester, etc. Since they are obtained by addition polymerization of ethylene oxide, normally, various types with a degree of polymerization are obtained rather than simple compositions. The solubilization of these surfactants in water can be evaluated by measuring the clouding point. If the lipophilic group is the same, the clouding point becomes higher as the length of the polyoxyethylene chain increases and they become more hydrophilic. Since these types of surfactants have excellent emulsifying and solubilizing abilities, these are used as emulsifiers in creams and milky lotions, and as solubilizers for perfumes and pharmaceutical agents, etc., in lotion. 5.2.4.2. Polyhydric alcohol ester type non-ionic surfactants These surfactants are produced by converting fatty acid esters of some of the hydroxyl groups of polyhydric alcohols, starting from glycerin, to fatty-acid esters and leaving the residual hydroxyl groups as hydrophilic groups. For example, monoglycerides are produced by esterification; they can also be produced by ester conversion from fats and glycerin. The best polyhydric alcohols to use are glycerin and trimethylol propane with three hydroxyl groups, pentaerythritol and sorbitan with four hydroxyl groups, sorbitol with six hydroxyl groups, and sucrose with eight hydroxyl groups. They can also be synthesized to compounds with several ester bonds from monoesters using the abovedescribed reaction from polyglycerin and raffinose, etc., with even more hydroxyl groups. Typical examples in this group are mono or diglycerides, sorbitan higher fattyacid esters, and sucrose higher fatty-acid esters, etc. Most of these types are hydrophilic to some extent and form emulsions in water; monoglycerides are combined with hydrophilic surfactants and used in cosmetics. Moreover, several HLB type non-ionic surfactants can be produced by addition polymerization of appropriate ethylene oxide to the residual hydroxyl groups. For example, such surfactants can be produced by addition polymerization of appropriate ethylene oxide to the residual hydroxyl groups of the sorbitan higher fatty-acid monoester and hardening with natural castor oil as well as by ethylene oxide addition. These surfactants show good emulsifying and solubilizing ability so they are widely used in skin care cosmetics. 5.2.4.3. Ethyleneoxide-propyleneoxide block polymers CH3

HO (CH2 CH2O). (CH CH^On (CH2 CH2O), H (m + n + m = 20—80, n = 15—50)

Ethyleneoxide-propyleneoxide block polymers contain both lipophilic groups glycol and hydrophilic groups from polyethylene glycol, so various surfactants having different HLBs can be obtained by freely changing m and n in the above chemical formula. These compounds have a comparatively larger molecule than other surfactants and are characterized by low skin irritation. They are marketed under the brand name Pluronic and are used widely.

134 New cosmetic science

5.2,5. Other surfactants 5.2.5.1. Polymeric surfactants Many early surfactants contained about 10-18 carbon atoms as the lipophilic group and had a molecular weight of about 300. If ethylene oxide propyleneoxide block polymers are combined with many polyoxyethylene, it is possible to obtain a molecule with a weight of 1000-2000 but normally the molecular weight is less than 1000. Based on this, polymeric surfactants could be described as surfactants with a high molecular weight. For example, polyvinyl alcohol can be made into fiber and film but when it is used for the action of emulsification or coagulation, it could easily be described as a polymeric surfactant. Based on this concept, sodium alginate, starch derivatives, and tragacanth gum, etc., can be used as emulsifiers, flocculants and dispersants. 5.2.5.2. Natural surfactants Lecithin is a well-known natural surfactant combining the anionic groups of phosphate esters with the cationic groups of quaternary ammonium salts. Lecithin is obtained from soy beans and egg yolks and the main components are phosphatidyl serine, phosphatidyl ethanolamine, phosphatidyl choline. In cosmetic applications, lecithin is used in milky lotions and creams because it has a refreshing feeling on use and softening properties. Recently, lecithin has been used to form liposomes which have a bilayer membrane. Many other natural surfactants have long been known and used including lanolin, cholesterol and saponin.

5.3. Humectants Maintaining a young-looking skin is closely connected with moisture content^^'^^^ One of the most important functions of cosmetics is maintaining skin moisture^^^. The keratin layer of the skin contains natural moisturizing factors^^-^^^ (NMF) with hydrophilic moisture absorbing compounds; NMFs are known to play an important role in skin moisturizing (Table 5.1). It is believed that the sodium salt of sodium pyrrolidonecarboxylate is the most important factor in NMF^^'^^^ NMF is not the only important factor in considering skin moisture; it is also important to consider preventing loss by bonding or surrounding, the presence of oils such as intercellular lipids and sebum controlling moisture evaporation, and holding water, the presence of mucopolysaccharides in the dermis. Cosmetics should be able to mimic this natural moisture retention mechanism. Humectants are water soluble materials with a high water absorption and they are a very important component in the aqueous phase of cosmetics. A wide variety of humectants are used in cosmetics including polyhydric alcohols like glycerin, propylene glycol, sorbitol, and including the main component of NMF, pyrrolidonecarbonate and lactates. Recent advances in biosynthesis technology has also permitted production and use of large amounts of sodium hyaluronate. As described previously, humectants play an important role in cosmetics but at the same time they also work to maintain the moisture content and stabilize the cosmetic itself. In addition, they also have bacteriostatic and fixative activities.

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Table 5.1. Composition of NMFi^,^^) Amino acids PCA(pyrrolidone carboxylic acid) Lactates Urea NH3, uric acid, glucosamine, creatinine Citrates Na 5%, K 4%, Ca 1.5%, Mg 1.5%, PO4 0.5%, CI 6% Sucrose, organic acids, peptides, other materials

40% 12% 12% 7% 1.5% 0.5% 18.5% 8.5%

(O.K. Jacobi : Proc. Sci. Sec. of Toilet Goods Assoc, 31, 22, 1959.) (H.W. Spiet, G. Pascher : Hautarzt, 7, 2, 1956.)

The main requirements of a humectant are listed below: (1) must have appropriate water absorption ability (2) must maintain water absorption ability (3) water absorption must not be influenced by changing environmental conditions (temperature, humidity, etc.) (4) water absorption ability must maintain moisture in skin (5) must have lowest possible volatility (6) must have good miscibility with other constituents (7) must have lowest possible freezing point (8) viscosity must match usage and feel good on skin (9) must be safe (10) must be as colorless, odorless and tasteless as possible In addition to having water absorption and moisturizing properties over a wide range of humidities, humectants must have densities matching the system they are used in. Even when the humectant is used incorrectly, the correct functions must still be maintained and reverse effects should not be possible. 5.3.1.

Glycerin CH2OH CHOH

I

CH2OH

Glycerin has long been used as a humectant and it is still widely used even today. It is obtained as a byproduct in manufacturing soap or fatty acids from plant and animal fats and oils. When dehydrated and deodorized, it is a colorless, odorless liquid. 5.3.2. Propylene glycol CH3

I

CHOH

I

CH2OH

136

New cosmetic

science

The common form is 1,2-propylene glycol. Although it looks and feels much like glycerin and is colorless and odorless, it has a better feeling on use due to its lower viscosity than glycerin. 5.3.3. 13-Butylene glycol:

CHsCH(OH)CH2CH20H

1,3-Butylene glycol is obtained by hydrogenation of the aldol condensate of acetoaldehyde as a colorless, odorless liquid. It is very safe and is used in creams and milky lotions, etc. 5.3.4. Polyethylene glycol:

HO(CH2CH20),H

Polyethylene glycol is obtained by adding ethylene oxide to water or ethylene glycol under alkaline conditions. It is not a uniformly simple compound but is a mixture polymer with various degrees of polymerization. It is a liquid at normal temperatures with an average molecular weight ranging from 200 to 600; semi-solid forms have increasing molecular weights ranging from 1000, 1500, 4000 to 6000. Generally, polyethylene glycol is colorless and odorless and its water absorption ability decreases with increasing molecular weight. It is used in creams, milky lotions, etc. 5.3.5.

Sorbitol CH2OH

I

(CH0H)4

I

CH2OH

This sugar alcohoP^^ is contained in the juice of apples and peaches, and is a white odorless solid. It is obtained by reduction of glucose. In comparison to the previously described humectants, it has lower hygroscopic property and it has a humectant effect at low humidity. It is used in creams, milky lotions, toothpastes, etc. 5.3.6. Sodium lactate:

CH^CHiOHjCOONa

Lactates are an important group of natural humectants occurring in NMF along with PC A (pyrrolidonecarboxylate). They have a higher water absorption ability than the lower-alcohol types. 5.3.7. Sodium

2-pyrrolidone-5-carboxylate CH2~CH2

0 ^ ^N^\ ^COONa H

Raw materials of cosmetics

137

Table 5.2. Water absorption ability of sodium 2-pyrrolidone-5-carboxylate^^^ Compound Pyrrolidone carboxylic acid Sodium pyrrolidone carboxylate Gylcerol (comparison)

31% RH

58% RH

lmax)^^^- Fig5.2 also shows the absorption spectrum of some typical UV absorbents^^^ Although it is possible to assess the effectiveness of UV absorbents by measuring their UV transmission or absorbance at a fixed concentration in an appropriate medium, since the absorption and absorption position changes with the type of solvent, etc., it is very difficult to evaluate the effectiveness accurately. At present, the most commonlyused method for measuring the UV absorption efficiency is to measure the actual human sun protection factor (SPF) (refer to Part II Chapter 5)^3).

5.6. Antioxidants Cosmetics are composed of fats, oils, waxes as well as surfactants and perfumes, etc.; some of these compounds contain unsaturated bonds. In particular, it is presumed that fats and oils with two or more unsaturated bonds are easily oxidized. In cosmetics, this reaction produces compounds with bad smells or causes safety problems such as skin irritation. To prevent these changes in quality, it is necessary to add antioxidants to cosmetics to control this oxidation reaction. Oxidation mechanisms are classified into two types: auto-oxidation, and non-radical oxidation. Auto-oxidation proceeds in the presence of oxygen via a radical-chain mechanism. Non-radical oxidation proceeds in the presence of ozone, single oxygen, etc. 5.6.1, Auto-oxidation

mechanism

Auto-oxidation is a radical chain reaction occurring due to the presence of 20% oxygen

Raw materials of cosmetics

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Table 5.5. Main ultraviolet absorbents

Benzophenon derivatives (1) 2-Hydroxy-4-methoxybenzophenone (2) 2-Hydroxy-4-methoxybezonphenone -5-sulfonic acid (3) Sodium 2-hydroxy-4-methoxybezonphenone-5-sulfonate (4) Dihydroxy-dimethoxybenzophenone (5) Sodium dihydroxy-dimethoxybenzophenone sulfonate (6) 2,4-Dihydroxybenzophenone (7) Tetrahydoxybenzophenone Para-aminobenzoate derivatives (8) Para-aminobenzoic acid(PABA) (9) Para-aminobenzoate (10) Glyceryl para-aminobenzoate (11) Amyl para-dimethylaminobenzoate (12) Octyl para-dimethylaminobenzoate

-OCH3

288,325 285,320

HO SO3H

''^

(Q^co^0^ocu, HO (2)

H^N-^O^-CO^H

288

(8) CH3

/N~KQ>~CO, - CH, - CH - (CHJsCHs CH3

Methoxycinnamic acid derivatives (13) Ethyl para-methoxycinnamate (14) Isopropyl para-methoxycinnamate (15) Octyl para-methoxycinnamate (16) 2-Ethoxyethyl p a r a - m e t h o x y c i n namate (17) Sodium para-methoxycinnamate (18) Potassium para-methoxycinnamate (19) Di-para-methoxycinnamoyl-mono-2 -ethylhexanoyl glycerol

(Imax)

Structure

UV Absorbent (Chemical Name)

^— (12)

1 CH2CH3

310

CH3 0 - x O ) ^ C H = CH-C02-CH3CH(CH2)3CH3 (15)

312

CH2CH3 CH20CO-CH(CH2)3CH3

C H 3 0 - / P ^ C H = CH-C02CH vrrv 1

' ru Url2Url3

CH30-(Q)-CH-CH-C02CH2 (19)

Salicylic acid derivatives (20) Octyl salicylate (21) Phenyl salicylate (22) Homomenthyl salicilate (23) Dipropylene glycol salicylate (24) Ethylene glycol salicylate (25) Myrystil salicylate (26) Methyl salicylate

312

corl'"' © r j d^cH3

308

(22)

CH3

Other (27) Urocanic acid (28) Ethyl urocanate (29) 4-t-Butyl-4'-methoxydibenzoylmethane(Parsol A) (30) 2- (2'-Hydroxy-5-methylphenyl) benzotriazole (31) Methyl anthranylate

1

^ = ^

CH3

II

II

0

^ ^

0 358

(29)

CH3

a:>^

298,340

HO

(30)

(Society of Japan Pharmacopoeia : The Japanese Standards of Cosmetic Ingredients, 2nd Edition, Yakujinipposha, 1984) (Japan Cosmetic Industry Association : Japan Cosmetic Ingredients Dictionary, 2nd Edition, Yakujinipposha, 1989)

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. Also, arbutin shows inhibition of melanin production without being metabolized to hydroquinone.

( I ) Arbutin

The in vivo effect of arbutin on UV-induced pigmentation of human skin has been investigated by double-blind tests and it has been reported that applying milky lotions containing arbutin to the skin has some effect (see Chapter 11). 6.L2. Kojic acid Kojic acid is a y-pyrone compound with the structure shown in II. It is produced mainly by microbial fermentation using aspergillus and penicillium spp. and is important in imparting both color and flavor to miso, soy sauce and Japanese sake. Both in vivo and in vitro experiments have shown that kojic acid inhibits melanin production. HO

0

"O

CH2OH

(II)Kojic acid

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In non-cellular in vitro test systems, kojic acid inhibited the activity of mushroom tyrosinase, goldfish and the black guinea pig tyrosinase. In the case of mushroom tyrosinase, the activity was inhibited by a non-competitive inhibition mechanism. This inhibition has been shown to be due to chelation of Cu, a prosthetic group in tyrosinases^ In studies at the cellular level using B16 melanoma cell cultures, it has been confirmed that addition of kojic acid to the cell culture reduces melanin production and tyrosinase activity^\ In in vivo tests, creams containing kojic acid compounds have been reported as effective in preventing pigmentation changes in human skin due to exposure to UVA and UVB7). 6.1.3. Vitamin C and its derivatives Vitamin C is known by the name, ascorbic acid and it is a typical pharmaceutical agent long used in whitening cosmetics to control production of melanin. Its effect is twofold: it reduces the melanin intermediate compound, dopaquinone, in the tyrosinase reaction which produces melanin from tyrosine, and it also reduces the dark colored oxidized melanin to the lighter colored reduced form. Vitamin C is very safe but very unstable. Therefore various derivative compounds (III) are used because of their better stability. Vitamin C phosphate (magnesium salt) has been developed due to its high stability in aqueous solution. When vitamin C phosphate (magnesium salt) is incubated with skin homogenate, vitamin C is released. Moreover, since vitamin C is detected in guinea pig skin after continuously applying vitamin C phosphate (magnesium salt) but is not detected in the untreated skin, the effect of vitamin C phosphate (magnesium salt) is due to the vitamin C metabolized in the body^\ In in vivo tests on the control of melanin production, when products containing vitamin C phosphate (magnesium salt) are used over the long term on highly-pigmented skin after UV exposure, skin color value recovers much faster than in untreated areas^\ 3/2Mg^^ HO

OH

NaO

HOCH

OSOsNa

0.

HOCH

I

HOCH

I

HOCH2

I

HOCH2

(III-l) Vitamin C

HOCH2

(III-2) Vitamin C-2-sulfate HO

^OPOa"

OH

(III-3) Vitamin C-2-phosphate

HO^

^o>°

/OCO(CH2)i4CH3

o

HOCH

0

HOCH

I

I

CH3 (CH2) 16 CO CH2 CH3 (CH2) H C O CH2 11 II 0 O (III-4) Vitamin C-stearate (III-5) Vitamin C-2,6-dipalmitate (III)

Vitamin C

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151

6.2. Hair growth promoters The causes of male scalp hair loss (alopecia) are: (1) reduced hair follicle function due to effect of male hormones, (2) reduced physiological function of scalp, (3) reduced metabolism function of hair follicle and hair bulb, (4) reduced blood flow due to scalp tension, (5) poor nutrition, (6) stress, (7) side effect of medicines, (8) genetic reasons, etc., (see Chapter 2). However, the reasons for hair loss are not completely understood. Consequently, hair growth promoters include various compounds to alleviate these causes of hair loss. Most products focus on components that stimulate the activity of the hair matrix and blood capillaries. These compounds promote hair growth by supplying nutrients through promotion of blood circulation and activating the hair follicles in the catagen and telogen phases. Hair growth promoters are classified according to their active ingredients and purpose. 6.2.1.

Vasodilators

Vasodilators which improve the flow of blood in the peripheral blood vessels are formulated in hair-care cosmetics. They can be classified into blood-flow stimulants which restore blood circulation and hair-follicle stimulants which improve secondary blood circulation. 6.2.1.1. Blood flow stimulants The principal blood flow stimulants used in hair growth promoters are swertia extract (swertinogen), cepharanthine, vitamin E and its derivatives, y-orizanol, etc. Swertia extract is an extract containing bitter glycosides of Swertia japonica, Makino, a member of the Gentian family; its principal component is swertinogen. It promotes blood flow by dilating the fine capillaries in the skin thereby supplying nutrients and energy to the hair matrix. Cepharanthine is an alkaloid extracted from the root of Stephania cepharanthia, Hayata, a member of the Tudurafuji family. It functions by dilating the blood capillaries. Vitamin E works directly on the skin blood supply and acts by promoting blood flow through vasodilatation of the blood capillaries. 6.2.1.2. Hair follicle stimulants The principle hair follicle stimulants are tinctura capsici, tinctura zingiberis, tinctura cantharidis, nicotinic acid benzyl ester, etc. Tinctura capsici is an ethanol extract of the fruit of the chili pepper. Capsicum annuum, Linneus. The spicy component, capsaicin, promotes hair growth by stimulating the hair root. Tinctura zingiberis is an ethanol extract of the root of Zingiber officinale, Roscoe. The stimulants, zingerone and shogaol both promote hair growth by stimulating the hair root. 6.2.2. Nourishing

agents

Vitamins and amino acids are used to prevent the undernourishment of cells surrounding

152 New cosmetic science

the hair matrix due to insufficient blood circulation around the dermal papilla and hair follicle. 6.2.2.1. Vitamins The principal vitamins are A, Bj, B2, Bg, E, E derivatives, pantothenic acid and its derivatives, and biotin. 6.2.2.2. Amino acids The principal amino acids are cystine, cysteine, methionine, serine, leucine, tryptophan as well as amino acid extracts, etc. 6.2.3. Estrogens (follicle hormone) Since male sex hormones (androgens) are one of the main causes of male scalp hair loss (alopecia), female sex hormones (estrogens) can be used to counter their effect. The main ones are estradiol, ethynyl estradiol, etc. 6.2.4. Hair root activating agents Hair root activating agents improve the function of the hair matrix when reduced by the abnormal activity of various enzymes affecting hair growth. The principal agents are pantothenic acid and its derivatives, placenta extract, allantoin, and quaternium-73. 6.2.5.

Humectants

Humectants prevent the hair from becoming too dry. The principal ingredients are glycerin, pyrrolidone carboxylate. Other hair growth promoters are described in Section 6.5.1. Anti-dandruff and Anti-itching Agents.

6.3. Skin-care agents Skin-care agents achieve an enhancement of the basic functions of cosmetics, add new functions and help maintain healthy skin as well as preventing rough skin. Types of skincare agents include anti-inflammatory agents, astringents, refrigerants, vitamins, hormones and antihistamines. 6.3.1. Antiinflammatory

agents

Anti-inflammatory agents are used to prevent localized inflammation of the skin resulting from external stimuli such as shaving. Typical anti-inflammatories are ^glycyrrhetinic acid, derivatives (IV) of glycyrrhetinic acid, allantoin, azulene, £aminocapronic acid and hydrocortisone (V).

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153

COOH

H HO/I H Y — - f COOH OH H (IV) Di-potassium glycyrrhetinic acid

(V) Hydrocortisone

6.3.2.

Astringents

Astringents are used to refresh and regulate the skin. Typical examples are zinc oxide, zinc sulfate, aluminum hydroxyallantoin, aluminum chloride, zinc paraphenol sulfonate, tannic acid, citric acid, lactic acid, etc. 6.3.3.

Refrigerants

Menthol (VI) and camphor, etc., are used for their cooling effect on the skin. OH ^^C-(

VCH CH3

(VI) Menthol

6.3.4.

Vitamins

At the same time as playing an essential role in maintaining the physiological functions of the entire body, vitamins are important in maintaining the physiological functions of the skin, and they are used to prevent skin diseases caused by vitamin deficiencies. 6.3.4.1. Vitamin A Vitamin A is used in the form of retinol or fatty acid esters such as palmitate and acetate. It is effective in preventing skin abnormalities such as dry skin and keratosis.

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6.3.4.2. Vitamin B group The B vitamins are used in the form of 65 (pyridoxine hydrochloride) (VII.l) and its fatty-acid esters) and as derivatives of nicotinic acid (VII.2) (nicotinamide, and the benzyl ester). It is useful in preventing seborrhea, and eczema and also activates skin regeneration. CH2OH J^CH.OH

HO

^ ^ C O O H

(VII-1) Pyridoxine

(Vll-2) Nicotonic acid

(Vll-3) Vitamin D2 (Ergocalciferol)

CH3

CH3

1

CH3

I

I

I

CH,lcH,-CH3-CH-CH2 + CH3-CH3-CH-CH,-hCH,-CH3-CH-CH3

(VIl-4) Vitamin E (or-Tocopherol) COOH

I

CH2

I

CH2

I

CH3OH

I ' I

HO-CH2-C-

I

CH3

CH2

O

I

II

CH2

CH-C-N-CH2-CH2-COOH

I

I

H

(VII-5) Pantothenic acid

/

H

CH—C—NH

I

\C. =

/

0

CH2—C NH H (VII 6) Vitamin H (Biotin)

6.3.4.3. Vitamin D Vitamin D prevents eczema and dry skin. Several percent of vitamin D obtained by UV exposure of ergosterol is dissolved in edible oil to be incorporated in cosmetics (VII.3). 6.3.4.4. Vitamin E Vitamin E is used as the fatty-acid ester (acetate). It is know to promote blood flow and inhibit oxidation (VII.4).

Cosmetics and pharmaceutical

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155

6.3.4.5. Pantothenic acid Pantothenic acid (VII.5) prevents skin or lip inflammation. It is used as calcium pantothenate and panthenyl ethyl ether. 6.3.4.6. Vitamin H Vitamin H (VII.6) is called biotin; it prevents skin inflammation. 6.3.5.

Hormones

It is well known that hormones play a major role in maintaining skin homeostasis. 6.3.5.1. Follicle hormone (estrogens) Estradiol (VIII) and its ester, as well as estron, ethynyl estradiol, etc. are used. H3C OH

HO (Vlll) Estradiol

6.3.5.2. Adrenocortical hormone (ACH) Cortisone and its ester, as well as hydrocortisone (V) and its ester, prednisone, prednisolone, etc. are used. 6.3.6.

Antihistamines

Histamines are produced as a result of the slight stimulus when the skin is rough even if it is not caused by pathological conditions such as a rash or allergy; these histamines make the skin itchy and abnormal. Various antihistamines are used to prevent this effect of histamines. Their use is also regulated by legislation. Diphenhydramine hydrochloride (IX), chlorpheniramine malate, glycyrrhizin derivatives, etc., are typical antihistamines.

O^

CHOCHaCHsNCr^u' • HCl

(IX) Diphenhydramine hydrochloride

6.3.7. Others (1) (2)

Shampoos, rinses, and soaps used to keep skin and hair clean contain anti-bacterial agents such as zinc pyrithione, trichlorocarbanilide, triclosan, etc. Some plant extracts showing anti-inflammatory and cell rejuvenation activities such as aloe extract, ginseng extract, licorice extract, rhubarb extract, chamomile extract, loquat oil, etc., are also used.

156 New cosmetic science

6.4. Anti-acne agents Acne has a variety of causes (see Chapter 1) and many different agents are used in combination in cosmetics to counter the various causes (Fig. 6.2). Excess sebum secretion is countered by sebum secretion inhibitors whereas keratin blockage of hair follicles is treated with keratolytic agents and corneocyte desquamating agents; the increase in bacteria is controlled using antibacterial agents. 6.4.1. Sebum secretion

inhibitors

Excess secretion of sebum is due to the action of male hormones. Consequently, it is necessary to control sebum secretion from the skin. Based on this observation, female sex hormone (estrogens), which is antagonistic to male sex hormones (androgens), is used to control sebum. However, since this female sex hormone is a powerful agent, its use in cosmetics is very limited. The amounts and types vary from country to country but their use is not permitted in cosmetics and OTC drugs in the USA. The main forms of female sex hormone (estrogens) used in cosmetics are estradiol, estron, and ethynyl estradiol. In addition, vitamin Bg is also used due to its antiseborrhoeic action. 6.4.2. Corneocyte desquamating

agents

When acne occurs, there is excess keratinization in follicles and comedos result; to open Effect of Hormones, etc. Excess Skin Lipids < ^

Sebum secretion inhibitors

Decomposition by lipase derived from bacteria

t

Bacteria

, liquid crystal emulsification^^^ etc. The methods discussed so far are for producing O/W emulsions with a particle size at the submicron level or greater than 0.1 //m. However, there are also methods for producing transparent and semitransparent emulsions (ultrafine emulsions) with a particle size below 0.1 //m. In external appearance, these emulsions seem the same as microemulsions described earlier, but the equilibrium phase diagram shows a dual liquid phase system and such emulsions simply have an extremely smaller particle size than that of normal emulsions. These emulsions can be produced by cooling of the microemulsions formed in non-ionic surfactant-oil-water systems at high temperature (Fig. 7.5). This procedure is included in the condensation method described above. However, as the emulsion particles are extremely small, such emulsions are more readily rendered unstable by Ostwald ripening (described in Section 7.1.4.3) than normal emulsions. Good stability can be obtained by selecting the suitable oil to use. In this production method, since there is a linear relationship between the ratio of the oil and surfactant and the diameter of the emulsion particles, an advantage is the ability to control the particle diameter by changing the ratio of the oil and surfactant. There are comparatively fewer reports on W/O emulsions than O/W emulsions. There are the gel-emulsification method and emulsification methods using clay minerals. In the former method, aqueous solutions of amino acids or their salts and aqueous solutions of reduced sugars such as sorbitol and multitol are added by stirring into a hydrophobic surfactant comprised of a fatty-acid partial ester of a polyvalent alcohol with three or more hydroxyl groups to create a stable gel including the aqueous solution in the surfactant. When oil and then water are added to this gel, a W/O emulsion is produced. The method using amino acids^^^ was reported in detail. The method of forming W/O emulsions^^) using water-swelling clay minerals is as follows. First, quaternary ammonium organic cations and non-ionic surfactants are intercalated into water swelling clay minerals to form new clathrate compounds. These complex compounds do not swell at all in water but they swell easily in oils to form viscous oil gels. When water is mixed into such a gel, an extremely-stable W/O emulsion is formed. These are quite different from the normal emulsions produced using usual surfactants so far and the emulsion particles are thought to be microcapsules formed with clay complexes. 7.1.4.3, Stability As described above, emulsions are essentially unstable and they break down when left untouched over long periods. Generally, this process can be broadly classified into three

Cosmetics and physical chemistry

177

phenomena: (1) creaming; (2) coagulation; (3) coalescence, as shown in Fig. 7.6. Ostwald ripening also occurs too. These phenomena are not restricted only to emulsions; they also generally occur in disperse colloids. (1) Creaming. In an OAV emulsion, the oil is the disperse phase, so the particles float when the specific gravity of the oil is lighter than that of water. (In a W/O emulsion, they sedimentate.) The velocity is found from Stokes' Law represented by Eq. (3). v - 2 g (pi-p2)r^ 9;;

(3)

where V is the velocity at which the particles move, g is the acceleration due to gravity, r is the particle radius, pi andp2 are the density of the dispersion medium and disperse phase, respectively, and rj expresses the viscosity of the dispersion medium. Consequently, to delay the creaming velocity, it is good to have a small particle diameter, a small difference in the densities of the dispersion medium and disperse phase, and a dispersion medium with a high viscosity. As a result, clearly, one important technological issue in producing emulsions is achieving small emulsion particle size (refer to Section 7.1.4.2). In addition, since creaming is affected by coagulation and coalescence described below, creaming sometimes evaluates complex stability. (2) Coagulation. A general force of attraction acts between colloid particles and when there is no force of repulsion acting between the particles, the particles tend to coagulate. The repulsive force acting between colloid particles is believed to be due to electrical charge and macromolecular adsorption.

Creaming V

N

f

J

N

Coagulation

L

J

Initia [ Dispersioi State

y////////A Coalescence

^

)

Fig. 7.6. Three types of separation exhibited by emulsions.

178 New cosmetic science

The DLVO theory^^^ can be applied to electrical repulsion systems. The general London-van der Walls attractive force, VA* is created between particles. On the other hand, a diffusion electrical double layer is formed around particles with a charged surface, and, as the particles approach, the electrical double layer overlaps to generate the electrostatic repulsion potential VR. These attraction and repulsion forces are functions of the distance between particles. When the particles get close, the total potential energy, Vj, which is the sum of V^ and VR determines whether or not the force acting between the particles is attractive or repulsive. (4)

VT=VA+^R

This relationship is shown qualitatively in Fig. 7.7. As the electrostatic repulsive force gets stronger, Vj curves as shown in the figure; as the particles get closer, the repulsive force acts and energy barrier (the peak of Vj) is formed and coagulation can occur when the kinetic energy of particles overcomes the energy barrier in this region. If this barrier (peak) becomes sufficiently bigger than the potential of thermal motion, kT, coagulation does not occur. When the height of the peak falls to about the same level as kT, the particles slowly coagulate. In addition, the SchultzHardy law which describes that coagulation proceeds more rapidly with increase in concentration and valency of ions in the solutions is explained by the DLVO theory, because the electrostatic repulsion force decreases in inverse proportion to the ion valency and the root of ion concentration. This theory is very important in emulsions, particularly systems emulsified using ionic surfactants, and if there is sufficient repulsive force in the system, the emulsion is stable for coagulation.

w o

Distance between Particles

Fig. 7.7. Particle interaction.

(Closer)

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179

It has long been known that polymers increase the dispersion stability of colloid particles. This phenomenon is thought to be due to the creation of a repulsive force caused by the overlap of a polymer layer adsorped on the surface of the colloid particles. This type of effect is known as the osmotic effect or the volume restriction effect^^). In simple terms, the repulsive force occurs because the osmotic pressure is generated at overlap of the adsorped layer of polymer with increase in polymer concentration as the result; dispersion medium penetrates the overlap and particles are pulled apart. Additionally, this explanation is also believed to apply to the stability of O/W emulsions prepared using non-ionic surfactants^^) explaining the greater stability produced by using a surfactant having a large mole number of added ethyleneoxide. This is an extremely important subject in considering the stability of non-ionic surfactant emulsions. (3) Coalescence. The term coalescence describes an aggregation in which the emulsion particles form an homogenous fusion. If the coalescence proceeds completely, the emulsion separates into two phases, which is the most stable state. Coalescence differs from creaming and coagulation in physical meaning. If an emulsion is stable against coagulation, then the coalescence cannot also occur and for this point coagulation theory can be applied to coalescence. Although the emulsion particles coagulate, the coalescence does not always occur. This is because coalescence occurs with the removal and breakdown of adsorped layers of the oil-water interface. Hence, it tries to increase the coalescence resistance by reducing the fluidity of the adsorped layer and forming a liquid crystal at the interface. Davies^^^ examined the structure of surfactants preventing coalescence from the role of the adsorped layer of surfactant in droplet fusion, discovering that surfactants having stronger lipophilic and hydrophilic properties are better. However, there may still be no clear explanation for coalescence. (4) Oswald ripening. So far, the focus has only been on coalescence as a cause of increasing particle size in emulsions, but recently, a phenomenon called Ostwald ripening has come to attention. In Ostwald ripening, when the particle diameter has a size distribution, the small particles become smaller and the large particles become larger and finally the small particles seem to disappear. This can be explained by Kelvin's law shown in Eq. (5). lnS,/S2=^(l/r,-l/r2)

.^.

where. Si and 52 are the solubilities of the particles of radius rj and r2, respectively, y is the interface tension, V is the molar volume of the disperse phase, R is the gas constant, and T is the absolute temperature. This equation shows that the solubility of a small oil droplet is larger than the solubility of a large oil droplet, explaining the diffusion of oil from small particles to large particles via the aqueous phase described above. Ostwald ripening has been reported as occurring in normal emul3JQjis28,29) aj^j i\\txt is a detailed explanation^^). When the particle size is smaller

180 New cosmetic science

than 100 nm, the above equation shows that the phenomenon called Ostwald ripening becomes more important. Recently, the importance of Ostwald ripening has become clear in the production^^D of ultra-fine emulsions (refer to Section 7.1.4.2). 7.7.5. Liposomes

(vesicle)

When an amphiphilic lipid such as lecithin forming a lamellar liquid crystal is dispersed in an excess of water, small capsules formed of bilayer membranes are easily created. These capsules are called liposomes or vesicles. If lamellar liquid crystals are formed by lipids, the hydrophobic lipid group is not restricted to two chains and vesicles can be formed with both mono-^^^ and tri-chain^^^ amphiphilic lipids. These vesicles differ from micelles in not being thermodynamically-stable, so it is possible to form vesicles of different sizes and structures depending on the production method. There are multilamellar vesicles having multiple layers formed from many sheets of bilayer membranes; there are small unilamellar vesicles formed from single-sheet membranes, and there are large unilamellar vesicles formed from single-sheet membranes. The vesicles have properties similar to microcapsules due to their structure and they have been tested for use in both the pharmaceutical and cosmetic fields. When they are used as products in their fields, it is necessary to pay attention to stability. 7.7. (5. Properties of powders The purpose of powders used in cosmetics is to impart color to the skin, to hide pigmented spots such as liver spots and ephelides, and to absorb perspiration and skin lipids. In addition, they are also used as support for perfumes, etc., and mild abrasive powders are used in toothpastes. The cosmetic products in which powders are used take various forms such as powders themselves, pressed powders, suspensions, and solids in which they are dispersed in solid lipids, etc.. This section explains how the properties of powders affect the properties of these types of product. The factors affecting the stability of suspensions are the same as those affecting disperse colloids and coarse dispersions (refer to Section 7.1.4). 7.7.6.7. Specific surface area The form of powder particles is quite variable so the size definition based on particle diameter is quite difficult. Consequently, the specific surface area, which is the surface area per unit weight or unit volume of the powder is commonly used as one measure of the size of powder particles. The specific surface area is found by measuring gaseous monomolecular absorption weight per unit weight of the powder^^^ 7.7.6.2. Apparent density The apparent density is the density calculated from the weight and cubic volume of the powder and it also includes the free space within the powder. It is also sometimes called the bulk density. The cubic volume of a unit weight of packed powder is also called the specific volume. The apparent density is measured by various packing methods^^^.

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7.1.6.3. Packing characteristics The packing characteristics of powders are expressed by the bulk density and specific volume described above, but porosity is also widely used. Porosity is expressed as shown below. Porosity = 1 -

Apparent Density True Density of Powder Particles

(6)

If the spheres are all the same size, the porosity can be calculated from the packing form (the way in which the particles are arranged) but there is no relationship with particle size. However, there is actually a relationship with the specific surface area and particle diameter; when the particle diameter becomes smaller than the inherent particle size (critical particle diameter), the porosity increases. This is because as the particle diameter decreases, interactions between particles (adhesion and coagulation, etc.) increase. 7.1.6.4. Flowability Powders range from those that flow easily and feel smooth to those that do not flow well and feel sticky. This difference in flowability is due to differences in the adhesion and coagulation of powders. The causes of adhesion and coagulation are believed to be van der Walls force acting between particles as well as static electric charges and capillary force due to the surface tension of water adhering to the particles. A number or parameters such as angle of repose, friction factor, and run-off velocity, etc., are used to evaluate flowability. This section describes the angle of repose method. When a powder is dropped onto a vibration free horizontal surface it forms a pile as shown in Fig. 7.8; the angle formed by the slope of the pile to the surface is the angle of repose. However, in some -^ases, when the pile takes the form of a curved or an irregular

/////////////////////////// a. High flowability powder

//////////////////////// b. Low flowability powder

b'. Fig. 7.8. Various forms of powder piles.

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New cosmetic science

slope, as shown in Fig. 7.8a',b' in the figure, the angle between the slope and the surface is smaller or greater than the theoretical angle. In these cases, it is better to measure H and D and calculate the angle. In measuring the angle of repose, obviously, the formation method of the pile is important, and there are a number of methods including: point supply method, cylinder draw-up method, parallel plate method, container inclination method, elimination angle method, sifter method, and rotating cylinder method. 7.1.6.5. Wettability When a water droplet rests on a horizontal surface made of a large polished solid, the droplet either spreads out and wets the surface, or the droplet remains a droplet and does not wet the surface. If oil is substituted for the water, the wettability of the oil is observed. Fig. 7.9 shows how the liquid droplet is formed. The angle {6) formed by the solid surface to the tangent at the contact point between the droplet surface and the solid surface is called the contact angle. This contact angle is one measure of the wettability of the solid by the liquid and it is a very important index used in mixing powders and liquids. However, it is not practically possible to measure the contact angle of powder particles directly, so the measurement is made by compressing the powder into a solid surface. 7.1.6.6. Surface modification The surface properties of powder particles can be changed by any of a number of methods. This is called surface modification. The objectives of surface modification in the cosmetics field can be broadly split into two: changes in chemical properties such as the particle surface catalytic action, and changes in the physical properties such as the dispersion medium wettability, etc. Many surface modification processes have been developed to date. Recently, an interesting surface modification method has been developed: ultra-thin films of polymers have been formed on powder surfaces from silicone monomers by using the powder surface catalytic action. This surface modification^'^^ can decrease the surface catalytic activities which cause color fading and fragrance changes. In addition, functional molecules can be introduced on these ultra-thin film surfaces of these modified powders which not only changes the physical properties of the powder surfaces but also adds new functional properties to the powders. This technology has applications beyond cosmetics such as packing materials for high-performance liquid chromatography. Air

Solid

Solid

a. d90°

Fig. 7.9. Liquid-solid contact angles.

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183

7.2. Rheology of cosmetics 7.2.1. Meaning of rheology in cosmetics Rheology is a scientific discipline dealing with changes in the form of things and with the dynamics of flow. The simplest rheological properties are viscosity and elasticity. Liquids such as water and liquid paraffin have viscosity but not elasticity. These types of materials are called Newtonian fluids. Newtonian fluids flow under even the smallest force, spending all the force in flowing and thereby consuming the energy. By contrast, things such as rubber and a metal spring have elasticity but not viscosity. These types of materials are called Hookian bodies. When a force acts on a Hookian body, the force is spent to change the shape of the body and the energy is stored instead of consumed. In cosmetics, the liquid state is usually handled as a Newtonian fluid, but some disperse systems such as milky lotions and creams demonstrate complex rheological properties incorporating both viscosity and elasticity. These types of materials are called viscoelastic bodies. The rheological properties of a material depend on its internal structure and are extremely important in cosmetic disperse systems. Rheological measurements are very useful in clarifying the internal structure of cosmetics. In addition, knowledge of the rheological properties of cosmetics is essential in designing cosmetic manufacturing machinery. Rheology of cosmetics is also important for usage standpoint. Cosmetics such as pomades, hair sticks and massage creams, depend upon tackiness and lubrication. Body powders use the lubrication effect of talc powders. In addition, attempts have been made to attach a rheological significance to characteristics that can be sensed by people like the extensibility and feel when using creams, etc., and the feel of hair after using shampoos and rinses. G. W. Scott Blair^^) coined the term psychorheology for this field. Moreover, research into the rheology of skin has seen some recent advances. 7.2.2. Flow forms First, the flow of a Newtonian fluid is considered. As shown in Fig. 7.10, the Newtonian fluid can be represented as flowing between two parallel surfaces of A cm^ separated by a distance of x cm. The under surface is fixed and a force of F dynes is applied in the direction of the arrow to the upper surface causing the surface to move at a velocity of u

Velocity = u I

Velocity = 0 Fig. 7.10. Newtonian fluid model.

^F

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New cosmetic

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Newtonian flow Bingham flow Plastic flow Pseudoplastic flow Dilatant flow Ostwald flow Shear stress Fig. 7.11. Various flow modes.

cm/s. Each layer of liquid between the two surfaces flows at the velocities shown by the arrows and ulx is constant. This value is proportional to the force per unit area {FIA) applied to the upper surface. The viscosity of the fluid, r], is found from Eq. (7).

u/x

(7)

FIA is called the shear stress, ulx is called the shear rate. The viscosity, r], is expressed in dyne sec/cm^ and is called the poise. The viscosity of water at room temperature is 1 centipoise. The Newtonian form of the flow is rare for a disperse system and various other forms such as Bingham, plastic, pseudoplastic, dilatant, and Ostwald flow have all been observed. These are shown in Fig. 7.11. When measuring the viscosity, an external force is applied to the system and this external force can change the structure of the system. Even if the shear stress (external force) is constant, the viscosity decreases with time during measurement and when the shear stress is removed, it returns to the original state. This effect is called thixotropy. When an external force is added to the system, it becomes solid, and when the force is removed, it returns to the original state. This property is called dilatancy. All the above phenomena are commonly seen in dispersed systems, and consequently, the measured viscosity of cosmetics varies greatly depending on the measurement method. Looking at this in another way, rheology measurement by a variety of methods is useful in clarifying the internal structure of cosmetics. 7.2.3. Rheology measurement methods^^^ In simple terms, the basic principle of rheology measurement involves obtaining the velocity at which a body flows as a function of the force required to make that body flow.

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185

However, when a force is applied that makes the material flow at a velocity greater than the velocity at which it can flow, even a Newtonian fluid exhibits elasticity, so the size of the shear rate becomes important. In disperse systems, when they are deformed largely, in many cases the particle dispersion changes accordingly. As a result, it is essential to select the most appropriate measurement method according to the measurement purpose. There are some measuring instruments used from the practical viewpoint although the measured values have no clear meaning. The following explains some rheology measuring instruments used both in laboratories and plants. 7.2.3.1. Capillary viscometer Typical viscometers are the Cannon-Fenske, and Ubbelhode viscometers based on the Ostwald type. The glass capillary has the form shown in Fig. 7.12; the time taken for a fixed amount of the test material to flow by gravity through a capillary from the upper measurement bulb to the lower test material bulb is measured. This system is best for measuring fluids such as lotions and liquid paraffin. It is used to determine the viscosity of liquids used to calibrate other viscometers. 7.2.3.2. Orifice viscometer This viscometer is composed of a tank with a small hole through which the test material flows. The time taken for a fixed amount of the test material to flow through the hole is measured. The Redwood and Saybolt viscometers are used to measure the viscosity of liquid paraffin, etc. There is also a type using extrusion under pressure which is best for measuring lipsticks and pomades, etc. 7.2.3.3. Rotating spindle viscometer In this meter, a rotating spindle is inserted in the test material and the additional resistance is measured by a spring. In commercial models, the speed of rotation can be switched and several types of spindle ranging from a thin rod (for high viscosities) to a round plate (for low viscosities) are available. This type of viscometer is used for emulsions and nail enamels.

Fig. 7.12. Capillary viscometer.

186

New cosmetic

science

"D -Torsion Wire

• Inner Cylinder (B) •Test Material 1-^- Outer Cylinder (A) Fig. 7.13. Rotating cylinder viscometer.

7.2.3.4. Rotating cylinder viscometer As shown in Fig. 7.13, this viscometer consists of a cylindrical container (A) and an inner concentric cylinder (B) connected to a torsion wire. The test material is placed between the inner and outer cylinders and when the outer cylinder is slowly rotated, the inner cylinder and the test material rotate in the same direction as the outer cylinder. The rotation of the inner cylinder is resisted by the torsion wire and the inner cylinder stops at the angle of rotation where the force applied from the test material and the torque of the torsion wire are in equilibrium. The viscosity of the test fluid can be found from the size of this angle of rotation. When the angle of rotation of the torsion wire is measured with increasing speed of rotation of the outer cylinder and then is measured by decreasing it, the curve plotting the angle against the rotation speed shows the hysteresis in some samples (thixotropy and dilatancy).

Recovery

Creep

1

/\

[E \ ^^''

/N

o U a a;

l___^^-d

1 F

/c //

S-i

U

t il

J^

/» B

|A

y. '1 Time (t) Fig. 7.14. Creep curve.

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187

7.2.3.5. Creep measurement When the outer cylinder is fixed and a constant torque is applied to the top end of the torsion wire, it is possible to measure the creep. Products with viscosities similar to creams and milky lotions show viscoelasticity at the low shear rate due to the mutual interaction between particles. Fig. 7.14 shows the result of creep measurement of a sample. In this figure, the ordinate is creep compliance and the abscissa is time. The creep compliance is the ratio of the strain to the stress. When a constant stress is applied to a sample with the torsion wire, the sample generates a strain and the curve A, B, C, D is obtained as a function of creep compliance against time. In addition, when the stress is removed at point D, the recovery is shown by the curve D, E, F. The instantaneous elasticity {E^, retardation elasticity (£'R), and viscosity {rjN) are determined by analyzing these curves. Since many cosmetics are disperse systems, they have both viscosity and elasticity and this method is useful for measuring the properties of these types of cosmetics. 7.2.3.6. Cone plate viscometer In this viscometer, the test material is inserted between a cone and a plate as shown in Fig. 7.15. The plate is turned by a motor and the additional resistance to the cone is measured by a spring. This equipment is useful for measuring the viscosity of materials ranging from milky lotions to creams by changing the size of the cone and the strength of the spring. Some viscometers are designed to measure viscosity by automatically increasing the rotation of the cone at a constant rate and then measuring as the rotation decreases. This type of equipment is useful for measuring materials such as cosmetics showing complex viscosity changes. 7.2.3.7. Forced vibration coneplate viscometer In this viscometer, the cone does not just rotate in one direction, it also oscillates. This is called a dynamic measurement method. It has the advantage of being able to measure extremely small deformations. In addition, when auxiliary equipment is used, it is possible to measure the Weisenberg effect shown by elastic materials.

Spring

-Cone Test Material - Plate

Fig. 7.15. Coneplate viscometer.

New cosmetic science

Oscillator 1

1

Strain

Stress

1

Linear Amplifier

Strain Amplifier

J

Decade Filter

1

Waveform Storage Device

#

Interface

Computer

I

Oscilloscope Fig. 7.16. Skin viscoelasticity meter (in vivo)^^\

7.2.3.8. Parallel-plate plastometer This viscometer is used to measure creep described in Section 7.2.3.5. The test material is squeezed between two flat parallel plates and a load is added to the upper plate. The rate at which the thickness of the test material decreases with load is measured. 7.2.3.9. Penetrator Although this is called a viscometer, it should perhaps be called a hardness meter. The force required for a needle or the tip of a rod to penetrate the test material is measured. This type of viscometer is useful for measuring the hardness of stick-type cosmetics and soaps, etc. The next three items do not deal with the rheology of cosmetic products. Instead they explain equipment for measuring the viscoelasticity of skin, and the usage sensibility of shampoos and rinses. 7.2.3.10. Skin viscoelasticity meter (in vivo) In this method, a small attachment is applied to the skin and the shear stress is measured by applying sine-wave oscillation in a linear direction through a mechanical linkage^^) (Fig. 7.16). During measurement, a sensor is pressed on the skin at a constant pressure Outlet

Hot Water Inlet

A : Pressure Tap B : Pressure Tap

AP : Pressure Loss

C : Hair Strand Fig. 7.17. Hydraulic hair friction force meter^^l

Cosmetics and physical chemistry

V Clamp

Hair Strand

x / v ^ l x

189

^Q"f ^"^ Pressure

A

B,B' constant number of revolutions

Fig. 7.18. Hair friction measuring instrument^^^

and the viscoelasticity is found by measuring the shear stress of the skin corresponding to a cyclical force applied according to the sensor signals. However, when pressure is applied to materials like skin, they are compressed and the mechanical properties change, so it is necessary to handle the viscoelastic value as a function of applied pressure. Since a pressure sensor fitted to the equipment is able to constantly monitor the pressure applied to the skin, it is possible to accurately measure the viscosity by treating it as a function of applied pressure. 7.2.3.11. Hydraulic hair friction force meter^^^ This equipment is for measuring the "roughness" or "smoothness" of hair at rinsing. Measurement is performed as shown in Fig. 7.17. The pressure drop, AP, occurring between points A and B when water is flowing, corresponds to the friction resistance between the hairs themselves; the smaller the value of AP, the smaller the friction between hairs at rinsing, meaning that the hair is not rough. 7.2.3.12. Hair friction measuring instrument^^^ The hair friction measuring instrument was developed to evaluate the smoothness of hair when touched by hand. The hair strand is fed through spongy rollers (NBR) and the friction force is measured as shown in Fig. 7.18. The results show good agreement with sensory evaluation tests.

References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

Clayton, W.: Theory of Emulsions, 5th edn., p. 178, J. & A. Churchill, London, 1954. Griffin, W. C : J. Soc. Cosmet Chem., 1, 311 (1949). Griffin, W. C : J. Soc. Cosmet. Chem., 5, 249 (1954). Davis, J. T.: Proc. 2nd Int. Congr. Surface Activity, 1, 426 (1957). Kawakami: Kagaku, 23, 546 (1953). Shinoda, K.: Nippon Kagaku Kaishi, 89, 435 (1968). Shinoda, K., Nakagawa, T., Tamamushi, B., Isemura, T.: Colloidal Surfactants, p. 17, Academic Press, New York, 1963. Preston, H.: J. Phys. Coll. Chem., 52, 85 (1948). Tomomasa, Kouchi, Nakajima: Yukagaku, 37, 1012 (1988). Shinoda, K., Saijo: Yukagaku, 35, 308 (1986). Prince, L. M.: Microemulsions, Preface, Academic Press, New York, 1977.

190 New cosmetic science 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39.

Davies, J. T., Rideal, E. K.: Interfacial Phenomena, 2nd. edn., p. 371, Academic Press, New York, 1977. Harusawa, F., Saito, T., Nakajima, H., Fukushima, S,: J. Colloid Interface Sci., 74, 435 (1980). Shinoda, K., Saito, H.: J. Colloid Interface Sci., 30, 258 (1969). Shinoda, K., Freberg, S.: Emulsions and Solubilization, Wiley, New York, 1986. Mitsui, T., Machida, Y., Harusawa, F.: Am. Perfum. Cosmet., 87 (1972). Suzuki, T.: Japan Patent, 57-29213 (1982). Sagitani, H.: J. Am. Oil Chem. Soc, 58, 738 (1981). Sagitani, H.: J. Dispersion Sci. TechnoL, 9, 115 (1983). Suzuki, T., Take, H.i., Yamazaki, S.: J. Colloid Interface Sci., 129, 491 (1989). Nakajima, Tomomasa, Kouchi: J. Soc. Cosmet. Chemist Japan, 23, 288 (1990). Kumano, Y., Nakamura, S., Tahara, S., Ohta, S.: J. Soc. Cosmet. Chem., 28, 285 (1977). Yamaguchi, M.: Yukagaku, 39, 95 (1990). Kitahara, Furusawa: Bunsan Nyuka no Kagaken, p. 104, Kogaku Tosho, Tokyo, 1979. Kitahara, Furusawa: Bunsan Nyuka no Kagaken, p. 202, Kogaku Tosho, Tokyo, 1979. Florence, A. T., Rogers, J. T.: J. Pharm. Pharmacol., 23, 153 (1971). Davies, J. T., Rideal, E. K.: Interfacial Phenomena, 2nd. edn., p. 366, Academic Press, New York, 1977. Higuchi, W. I., Misra, J.: J. Pharm. Sci., 51, 459 (1962). Davis, S. S., Round, H. P., Purewal, T. S.: J. Colloid Interface Sci., 80, 508 (1981). Kabal'nov, A. S., Pertzov, A. V., Shchukin, E. D.: Colloids Surfaces, 24,19 (1987). Imae, T., Trend, B.: J. Colloid Interface Sci., 145, 207 (1991). Tanaka, M., Fukuda, H., Horiuchi, T.: J. Am. Oil Chem. Soc, 67, 55 (1990). Kubo, Jimbo, Mizwatari, Takahashi, Hayakawa: Funtai Riron to Ouyo, Maruzen, Tokyo, 1979. Fukui, H.: Yukagaku, 40, 10 (1991). Scott Blair, G. W.: A Survey of General and Applied Rheology, Pitman, London, 1949. Sherman, P.: Industrial Rheology, Academic Press, London 1970. Umeya, J.: J. Biorheology Soc. Jpn, 4, 34 (1990). Fukuchi, Okoshi, Murotani: J. Soc. Cosmet. Chemist Japan, 22, 15 (1988). Fukuchi, Tamura: J. Soc. Cosmet. Chemists Jpn., 25 (3), 185 (1991).

8

Stability of cosmetics

Like other products, the stability of all cosmetics must be matched to the expected period of usage by the consumer as well as to the user's requirements. It is important to guarantee product quality by paying sufficient attention to the time required to distribute the product from the manufacturer to the consumer and to the actual usage period. Recently, it has not been sufficient to simply guarantee the feeling on use and performance; it has also become important to consider the safety and stability in usage as well as the disposal after use. The first half of this chapter describes the stability of base formulae and pharmaceutical agents at the research and production stages. The latter half describes the stability aspects of base formulae and containers in consideration of quality assurance for products when they are actually used. Guaranteeing the stability of cosmetics requires sufficient evaluation at the R&D stage as well as the establishment of design principles for the product itself.

8.1. Stability of base formulae and its testing To ensure that the various functions of cosmetics are realized, the first stage is to observe whether or not there are any changes in their physico-chemical properties. (1) Chemical changes: color change, color fading, fragrance change, staining, crystallization, etc. (2) Physical changes: separation, sedimentation, aggregation, blooming, sweating, gelling, unevenness, evaporation, solidification, softening, cracking, etc. These phenomena not only have a great effect on usability, but also make cosmetics unattractive and damage their image. Generally, the quality of cosmetics must be guaranteed until the consumer finishes them and manufacturers work on this assumption while focusing their research effort on improving the overall level. Guaranteeing product life helps greatly in securing consumer confidence. 8,LL

General preservation

tests

8.1.1.1, Temperature stability test In this test, cosmetics are tested at different temperatures to observe and measure the changes in the properties of samples with the lapse of time. (1) Test temperatures: -10°C, -5°C, 0°C, 25°C, room temperature, 30°C, 37°C, 45°C, 50°C, 60°C, etc. The most appropriate temperature is selected according to the sample properties. 191

192

New cosmetic science

(2)

Preservation period: 1 day to 1 month, 2 months, 6 months, 1-3 years, etc. The most appropriate period is chosen according to the sample monitoring purpose. (3) Observed items', changes in external appearance (color changes, color fading, color unevenness, foreign substances mixing, scratching, suspended materials, separation, sedimentation, sweating, blooming, crystallization, cracking, gelling, transparency, caking, luster, subsiding, capping, pinholing, aeration, mold growth, etc.); changes in fragrance: (direct observation, transfer of container odor, on use) (4) Measurement items and typical measuring instruments. pH: glass polarity pH meter Hardness: curd tension meter, Bikas hardness meter, Olsen hardness meter, rheometer, etc. Viscosity: Brookfield viscosimeter (B, H, E types). Redwood viscosimeter, Ferranti Cone and Plate viscosimeter, etc. (refer to Section 7.2) Turbidity: integrated spherical turbidity meter, concentrated light source method Particle diameter: microscope, colter counter, standard flay, grind meter Emulsion type: tester (volt-ohm-milliammeter) Softening point: Webrode method. Boiling method Water evaporation: desiccation method, Karl Fischer method, evaporation method (5) Evaluation: data for the above items is recorded over time and any abnormalities observed in the samples are used as feedback for the the formulation design. Generally, the stability range of observed items is determined by standardized evaluation methods such as the five point and O (good), X (bad) indications methods. Changes in viscosity with time and temperature indicate the gelling of emulsions while the changes in particle diameter indicate the states of coalescence, creaming and coagulation. These data make it possible to achieve a more stable balance in formulations. The noteworthy points in these observations as well as in the accelerated preservation tests described below are to ensure that the quality of materials for containers used in the preservation tests is the same as that for containers used in the market. The second most noteworthy point is to consider the decrease in amount of the cosmetic with use and to ensure that the stability is guaranteed in accordance with the usage method right until the end. The formulation and container must ensure the absolute minimum change in the functions and performance of the cosmetic throughout its usage life. 8.1.1.2. Photo-stability tests (light resistance) Cosmetics are often exposed to varying degrees of light in shop windows and they can be subject to direct strong sunlight or artificial light for long periods of time. Except for a few displayed in cases, most are displayed without their cases. Consequently, it is very important for cosmetics to be photo-stable. At present, the following methods are used to test and guarantee photo-stability. (1) Outdoors (sunlight) exposure test. Although there is no standard test, the changes in samples over a number of days, weeks, and months based on exposure to midsummer sun are observed. The observed items are usually changes in color and fragrance as described in item (c) of Section 8.1.1.1.

Stability of cosmetics

(2)

(3)

193

Inside (artificial light) exposure test. Since it is often difficult to monitor changes under fixed condition outdoors due to seasonal changes and the occurrence of rain, snow and mist, in many cases, the tests are performed using artificial light with a spectrum close to natural sunlight. A typical method uses a carbon arc fade meter and a xenon fade meter. The xenon arc lamp is an artificial light source producing a light spectrum very close to that of natural sunlight. The light source is composed of a long xenon arc tube and an infrared water filter. It has a water jacket and the main body (light source and sample stage) and the internal temperature can be adjusted between room temperature +15° and +80°C; the black panel temperature can be adjusted between 30° and 80°C. The sample is exposed to the light by mounting it in a rotating frame holder. The rotating frame circles around the xenon lamp and exposes the sample to the light. The rotation speed is constant and the total exposure is determined using a time switch; the distance of the sample from the lamp can be adjusted between 25 and 40 cm. Normally, samples are observed for fixed time periods at room and higher temperatures and the stability is evaluated as the degree of color change (AP) compared with controls (unexposed samples). Fig. 8.1 shows the spectra of sunlight, the carbon arc lamp and the xenon lamp (with filter) as well as the relative optical energy. The xenon arc lamp is an excellent light source having the same UV and visible light spectrum and energy levels as sunlight; the light color is white. Table 8.1 shows the relative similarity of sunlight, the xenon lamp and carbon arc lamp in the 300-400 nm band, which has the largest effect on color change; if the energy level of the 300-400 nm band is 1, the ratio of the energies in the 300-340 nm band and the 300-360 nm band is very similar for each type of light. Fluorescent light exposure test. This test is based on the idea that cosmetics are often exposed to light from fluorescent tubes in show cases. The hours of light exposure in 1 day is calculated and the color change over the required number of days exposure is observed.

Xenon lamp with filter Carbon arc lamp

1100 Wavelength (m/z) Fig. 8.1. Optical spectrum of sunlight, xenon lamp and carbon arc lamp.

194 New cosmetic science Table 8.1. Relative similarity of sunlight and different light sources in UV region

^^^^^^^^

Light Source

Wavelength (nm) ^ ^ ^ ^ ^ ^ ^ ^ 300—340 300—360 300-400

Sunhght

Carbon Arc

Xenon

0.20 0.44 1.00

0.18 0.33 1.00

0.18 0.37 1.00

S. 7.2. General performance and effectiveness tests The temperature and photo-stability tests described in items Section 8.1.1 are used to evaluate any deterioration in the original performance and effectiveness of each type of cosmetic. For skin care cosmetics, changes in the texture such as the extensibility and stickiness, luster, cleansing ability, lathering, etc., are important; in powder-type makeup cosmetics, changes in the lasting quality, covering power, applied color, etc., are important, while in point makeup like nail enamels and lipsticks, changes in adhesion (peeling), luster, drying speed, lasting quality, coloring ability, water resistance, oil resistance, etc., are important. In hair cosmetics, changes in setting and waving ability, effect on hair luster, coloring, bleaching, hair removal ability, etc., are important. Such tests evaluate any changes in the above characteristics and the results are reflected in the formulations providing the best combination of components and the best concentration of functional ingredients. 8.1.3. Aerosol stability tests Aerosol cosmetics are composed of a concentrate and propellants. Although the stability of the concentrate can be tested using the methods described in Sections 8.1.1 and 8.1.2 above, it is also necessary to confirm the stability of the final product separately as well. As there have been many cases of problems related to the structure and materials of the valve and concentrate, it is very important to investigate the following items sufficiently to ensure the stability of aerosol products. (1) Mutual solubilities of the liquid or compressed gas and the concentrate. (2) Change in ejected state from aerosol container. (3) Change in internal pressure and flammability. (4) Blockage of nozzle by setting agents such as hair setting lotion. (5) Foaming condition with temperature change. (6) Degradation of nozzle by volatile ingredients in aerosol products. (7) Gas leaks when inverted or turned on side. The following outlines the methods for testing the corrosion, leakage and blockage of aerosol containers. (1) Corrosion test: observe whether or not there is any rust on the surface of the aerosol container after it has been left upright and inclined at room temperature and elevated temperatures over the long and short term.

Stability of cosmetics

(2)

(3)

195

Leakage test: fill the aerosol with a predetermined measured test weight and determine whether or not there are any changes in the weight after the container has been left upright, horizontal and inclined at room temperature and elevated temperatures for long- and short-term periods. Blockage test: operate the test valve for a fixed length of time at a fixed temperature (low and high), and observe the ejected state. Spray the aerosol for a number of seconds, doing this daily, every other day or every other month to determine whether or not the valve becomes blocked.

8.1.4. Special accelerated stability tests The stability of cosmetics must be guaranteed until the consumer stops using or has used all of the product. For this reason, a number of special accelerated test procedures matching each product have been developed to guarantee the characteristics of the cosmetics over an extended usage period. The evaluation does not just use one test but evaluates the product using a combination of various tests. This method of evaluating stability does not just evaluate the stability of the base formulae; as described below, it also evaluates the stability of the pharmaceutical agents. From the viewpoint of research efficiency, as well as quality assurance for the various functions and stability of the cosmetic various tests have been developed and are carried out. Some typical accelerated tests are described below. 8.1.4.1. Temperature and humidity combination tests Special accelerated testing is performed by combining various temperatures and humidities. For example: temperatures 37°-50°C; humidities: 75-98%. 8.1.4.2. Cyclical temperature tests These tests are not conducted at a fixed temperature and humidity; to simulate the yearly and daily changes in temperature, the test temperature is changed cyclically a number of times each day. Fig. 8.2 shows an example of such a test. 8.1.4.3. Stress test This test takes the overall stress and time period of actual usage into consideration; it predicts the stable life span of the product from the physical changes induced by stress over a fixed level. The physical changes monitored by this test include changes in separability and emulsion particles (coalescence, coagulation, irregular form and viscosity). Two cycles per day

High Temperature

0

6^

Low Temperature Fig. 8.2. Cyclical temperature test.

196 New cosmetic science

It is commonly applied to liquid emulsions such as shampoos, rinses, milky lotions, and lotions containing powder, as well as paste type products such as toothpastes, packs, gels, creams and mascaras. (1) Centrifugal separation method. In this test, the product in its container is subjected to a centrifugal force by spinning at a constant speed and the separation is measured. The results of the test are reflected in the formulation of cosmetics in comparison with the stability observed in the static condition. (2) Vibration test. This method is used to verify the effect of vibration during transport by truck and train, etc., on cosmetics. The vibration amplitude and duration of the vibration machine are determined by investigating the vibration encountered during distribution. (3) Drop test. This method is used for powdery type cosmetics such as powdery foundation, eye shadow, brusher and face powder. The product in its container is dropped repeatedly from a fixed height to investigate its ability to withstand shock. The number of drops before breakdown is investigated to fix a standard for passing products. This guarantees the product when it is accidentally dropped by the consumer and for the assumed conditions inside a handbag. (4) Load test. This test is used to examine stick-type products like lipsticks and pencils by forcible bending. The load in actual usage is measured, and the product is tested at a load exceeding this load to observe the level at which deformation occurs. Standardization of the load angle, and distance from the pressure point are very important items; the results are the cumulative number of measured times to deformation. (5) Friction test. This test is used to evaluate the durability of soaps and enamels. In the case of soap, the test analyzes the wearing dissolution by dipping the bottom of the soap into water and applying a fixed load. The changes in the amount before and after testing are measured to determine the wearing dissolution. In the case of nail enamel, the wear is analyzed by applying a fixed frictional load to the dried nail enamel film and the film endurance characteristics are evaluated. The above describes some accelerated test methods, but they can only predict the stability of the base formulae over the elapsed time in the laboratory, so to increase the prediction accuracy, it is important to improve the match by checking this against data from the actual usage environment.

8.2. Stability of pharmaceutical agents and test methods 8.2. L Quality assurance for pharmaceutical agents in cosmetics Some pharmaceutical agents are easily degraded by atmospheric oxygen and they are often chemically unstable compounds. For example, vitamins A, Bi, B2, Bg, C, etc. are all unstable. Moreover, there may be ingredients with which a particular compound is incompatible when it is mixed together with them in a cosmetic system and some may be easily affected by changes in pH. The stability of pharmaceutical agents in quasi drug products is established on the basis of accelerated tests of drugs defined by law in Japan. These tests are carried out for 6 months or more, at a temperature of 40°± 1°C and

Stability of cosmetics

197

75 ± 5% RH. The stability data obtained by these test conditions are considered equivalent to data collected over 3 years or more at room temperature. Generally, the regulated content range is 90-110% and the test data is obtained three times from three lots (nine times total). To guarantee the stability of pharmaceutical agents in the product under these types of controls, first, it is necessary to verify the stability data at the level of raw materials. Next, base formulae whose stability over time can be verified are selected, and finally, it is necessary to select a container that minimizes the effect of light, etc., on the contents. To ensure the stability of pharmaceutical agents used in the product, it is also very important to previously understand the effect of the other ingredients used, as well as the effects of pH, temperature, and incompatible compounds, etc. In order to stabilize an unstable pharmaceutical agent in a product, it is very important to decrease oxygen in the container, add anti-oxidants and chelating agents, adjust pH, choose the optimum amount of agent, eliminate impurities, and choose the optimum temperature during the production process, as for example, in low-temperature emulsification and post-addition of agents. In addition, it is also important to maintain stability at the raw material level (cool and dark storage). Moreover, when there is a possibility of absorption by the container, it is extremely important to select the right container and container materials at the design stage. 8.2.2. Stability tests for quasi drug products Basically, quasi drug products are subjected to the same kind of strict quality regulations as ethical drug products. Consequently, one quick method of predicting the stability over time is to measure the stability of a product that has already been aged at 50°C or higher temperatures. Moreover, records related to quality testing, etc., must be kept for at least 5 years after obtaining approval if requested, and it is best if inspection and quality control sections are established to control records from the sections with responsibility for formulating and analysis.

8.3. Stability of mass-produced cosmetics Although there may be no problems in product prototypes and stability evaluation at the R&D stage, it has been reported that sometimes at the mass production stage there is separation and the desired viscosity and color shade may not be achieved. It is extremely important to pay attention to the following items to assure quality when scaling up production from the development to mass-production stages. (1) Variation in raw material lots (2) Differences in manufacturing conditions (temperature, shear stress, production time, addition method and sequence) (3) Differences in filling conditions (excessive cooling, re-dissolution, shear stress due to machinery, continuity) (4) Production amount (example: 1 kg -> 1 ton -> 10 tons) Such variations in manufacturing conditions cause the product quality of cosmetics to

198

New cosmetic science

vary from the desired quality, and it is most important at the R&D stage to give full consideration to the quality control procedures such as testing the effect of the ingredients and manufacturing processes so as to prevent any problems occurring before full-scale production starts. In other words, stability is not maintained point-by-point but is achieved through a broad approach. In the manufacturing plant, sometimes problems cannot be solved instantly; perhaps the solution is in the process conditions or perhaps in the ingredient formulation and sometimes sudden scaling up to mass production is not possible. In this latter case, it may be necessary to proceed step-by-step to full-scale production via an intermediate pilot plant. Problems discovered in points 1-3 above must be understood and solved.

8.4. Assurance stability based on usage environment As mentioned early in this section, the stability of the cosmetic must match the anticipated usage requirements, so the product quality assurance (stability and safety) must take into consideration how the consumer actually uses the product. For example: (1) Soaps and cleansers: may become soggy or have reduced viscosity or usability due to immersion in water (2) Sunscreens: may stain sports clothes and swimming costumes and the stain may be hard to wash off (4) Bath preparations: may cause damage to the bathtub or may stain towels with plant extracts, etc., in them or may be accidentally ingested or enter the eyes (5) Aerosols: solvents in aerosols may have a harmful effect on household goods, or gases may leak out due to misuse and the contents may not come out. (6) Cosmetics containing strong solvents: may damage spectacles, combs, sponges, bathroom fittings, etc. (7) Hair coloring products: may stain hands, towels and bathroom fittings and accessories. Although some examples are explained above, when considering the stability of cosmetics, thorough consideration must also be given to the possible occurrence of phenomena which are not only physico-chemical in nature.

9

Preservation of cosmetics

9.1. Need for adding preservatives to cosmetics In addition to their principal ingredients of oil and water, cosmetics often also contain such substances as glycerin and sorbitol which provide a source of carbon for microorganisms, and such substances as amino acid derivatives and proteins which provide a source of nitrogen for them. So, as for foods which contain similar ingredients, it is easy for them to be contaminated by fungi, bacteria and other microorganisms. However, no real comparison can be made between cosmetics and foods in terms of the risk of deterioration due to microorganisms, because the usage period is much longer for the former, extending to several years in some cases. It is therefore necessary to add preservatives to cosmetics for their long-term protection against putrefaction and bad smells due to bacterial contamination from the fingers and other sources during use. Among the microorganisms in our daily lives, the ones that contaminate cosmetics and proliferate inside them are mainly bacteria; but cosmetics are also contaminated by fungi and yeasts. The general characteristics of typical microorganisms contaminating cosmetics are listed in Table 9.1.

Table 9.1. General characteristics of microorganisms which contaminate cosmetics Fungi Optimum growth temper20—30° ature

Bacteria

Yeasts 25—30°

25—37°

Preferred nutrients

Starch Plant-based foods

Sugars Plant-based foods

Proteins, amino acids Animal-based foods

Optimum growth pH

Acidic

Acidic

Weakly acidic-weakly alkaline

Aerobic/anaerobic

Aerobic

Aerobic-anaerobic

Usually aerobic, sometimes anaerobic

Major products

Acids

Alcohols, acids carbon dioxide

Amines, ammonia acids, carbon dioxide

Typical species

Penicillium Aspergillus Rhizopus

Saccharomyces Candida albicans

Bacillus subtilis Staphylococcus aureus Escherichia coli Pseudomonas aeruginosa

199

200 New cosmetic science

9.2. Primary and secondary contamination Article 56 of Japan's Pharmaceutical Affairs Law (Sale, Manufacturing and Other Prohibitions) prohibits "The sale, manufacturing, etc. of drug products contaminated with pathogenic microorganisms or with those having the risk of contamination". In exactly the same way, it is undesirable to manufacture or sell cosmetics which are contaminated by pathogenic microorganisms. But even if the microorganisms are not pathogenic, contamination by them is inappropriate, from the standpoints of both user and manufacturer, because it signifies that the manufacturing process is unhygienic, there will be deterioration in product quality as time goes on and skin irritation will result from this. Contamination by microorganisms arising during production is called primary contamination and that arising during the use of the product by the consumer secondary contamination. Primary contamination often arises from bacteria in water (gram negative rods) while secondary contamination often results from bacteria from the hands and usage environment (gram positive cocci and gram positive rods). To prevent primary contamination arising during manufacturing and filling, it is necessary to provide a clean working environment by installing such equipment as dust filters in the ventilation system and dehumidifiers, sterilizing water by heat and ultraviolet treatment, sterilizing raw materials by ethylene oxide gas and heat treatment, washing manufacturing equipment and sterilizing it using heat or chemical treatment and educating workers on cleanliness at work, in order to ensure that production is carried out under clean conditions overall. Primary contamination may be prevented by strictly observing good manufacturing practice (GMP)^) and now products are becoming unacceptable to the consumer if they are not made in factories conforming to GMP. Every country has its own standards for live bacteria counts in the final product. The guidelines'^ of America's Cosmetics, Toiletries and Fragrance Association (CTFA) state that the number of live bacteria in 1 g of product must be less than 500 for baby products and eye makeup cosmetics and less than 1,000 for other products; and that pathogenic bacteria are unacceptable. The Japan Cosmetic Industry Association's own guidelines state that the number of live bacteria in 1 g of product must not exceed 1,000 and that pathogenic bacteria are unacceptable. Testing for microorganisms in cosmetics and attitudes towards pathogenic bacteria are explained in detail in "Microorganism Testing for Drugs and Cosmetics"^^ Coagulase positive Staphylococcus aureus, Escherichia coli species and Pseudomonas aeruginosa are examples of the pathogenic bacteria which must not be detected in cosmetic products and it is the responsibility of the manufacturer to carry out GMP control on a daily basis so that such sources of primary contamination are not detected. However, although there are absolutely no standards or testing for resistance to secondary contamination, every cosmetics company now carries out individual testing on the basis of the procedures in the 19th Edition of the US Pharmacopoeia^) and CFTA procedures^). There are a tremendous number of microorganisms in our daily living environment; in the air there are 8-35 x lO^/m^, in soil 1 x 10^-5 x lO^^/g and on the human scalp 1.4 x lOVcm^^). There are also large numbers of bacteria on our hands and faces and cosmetics are contaminated by them when we put in our fingers to take some out, put some

Preservation of cosmetics 201

back after taking too much on the hand or leave the cosmetic with the lid off for some time. Preservatives are added to cosmetics to prevent this contamination which they do by suppressing the proliferation of microorganisms and killing them in time, thus preventing deterioration of the product. However, it is necessary to make efforts to add the smallest possible amount by taking into account such items as the period of use and number of applications the volume of the contents is sufficient for, as well as the number of chances of contamination that there are with a particular form of container.

9.3. Antimicrobial agents Antimicrobial agents come under two headings depending on the reason for using them. 9.3.1.

Preservatives

Preservatives are added to cosmetics to suppress the proliferation of microorganisms which have contaminated them and to kill them in time, thereby preventing deterioration of the product. Suppressing the proliferation of microorganisms is called microbiostasis and preservatives make use of this action to prevent product deterioration. Preservatives do not have such a strong effect by themselves; the ones in general use blend in well with the ingredients of the cosmetic and gradually kill off the contaminating microorganisms in time. Typical ones are paraoxybenzoates which are commonly known as parabens. Parabens are also much used in food products. 9.3.2. Disinfectants and germicides Disinfectants and germicides are added to cosmetics with the purpose of sterilizing the surface of the skin and keeping it in a clean condition. The requirements of disinfectants and germicides are that they kill germs or reduce their numbers in a short period of time. The disinfectants and germicides used in anti-acne products, deodorants and other cosmetic products suppress the proliferation of the germs on the skin thought to cause acne, thereby preventing its occurrence as well as its aggravation, and kill or reduce the numbers of bacteria in the armpit thought to be a cause of body odor. Disinfectants and germicides are also used in dandruff control products because they have the ability to suppress Pityrosporum ovale, a yeast suspected of causing it. However, many problems have to be solved when actually using them: for example they may react with the other ingredients in the cosmetic, may not readily dissolve in it or their effectiveness may be greatly reduced due to reaction with proteins on the skin. Typical examples are benzalkonium chloride, chlorhexidine gluconate and trichlorocarbanilide (TCC). Disinfectants and germicides are also used for sterilization in order to prevent primary contamination during the manufacturing process. As the largest source of contamination in the manufacturing process are gram negative bacteria, many of which are very resistant to disinfectants and germicides, benzalkonium chloride and chlorhexidine gluconate (both water-soluble) are made into alcohol solutions when used. They are also made into

202 New cosmetic science

acid or alkaline solutions when used for this purpose. In order to prevent mixing with the product, GMP stipulates that it is essential to wash off such agents completely after use for sterilization. 9.3.3. Characteristics required of antimicrobial

agents

Not all antimicrobial agents may be added to cosmetics as some have undesirable characteristics and some may be used as either a preservative or a disinfectant/germicide depending on the purpose of the product. Antimicrobial agents are used on the basis of having as many as possible of the ideal characteristics'^) in the following list. (1) Efficacy against many species of microorganisms (2) Water solubility or easy dissolution in commonly used cosmetic ingredients (3) High safety, no irritation (4) Neutral with no effect on product pH (5) No reduction of product ingredient effectiveness (6) No adverse effect on product appearance (discoloration, etc.) (7) Stability over wide temperature and pH range (8) Readily available and stable supply (9) Low in price and economical to use

9.4. Antimicrobial agents used in cosmetics In Europe, a list of preservatives permitted in cosmetics has been published under the title EU Cosmetic Directive^) in the EU Official Journal. In the United States, the Food and Drug Administration (FDA) has published a list of substances (Prohibited and Controlled Substances) prohibited for use in cosmetics in its Code of Federal Regulations^^ which also contains preservatives. Preservatives used in cosmetics in the United States are listed in the International Cosmetic Ingredient Dictionary^^^ published by the CFTA. Table 9.2 lists the antimicrobial agents stipulated in Japan's Comprehensive Licensing Standards of Cosmetics by Category^^\ These quality standards have been drawn up by the Ministry of Health and Welfare on the basis of the Pharmaceutical Affairs Law and suggestions of the Central Pharmaceutical Affairs Council, and indicate upper limits on safety. For each antimicrobial agent, it is necessary to check such items as the solubility, safety, effective pH range, prohibitions on use, smell, color and their actual effect in a cosmetic product when considering their inclusion in cosmetics. The use of some antimicrobial agents is limited to soaps, shampoos and other products which are rinsed off after use and the quantities of some may be increased when used in such products. Antimicrobial agents whose use is controlled in Japan due to safety concerns are listed in Table 9.3.

Preservation of cosmetics

203

Table 9.2. Antimicrobial agents stipulated in Japan's comprehensive licensing standards of cosmetics by category

Agents

Structural formula

^^COOH

Benzoic acid

Salicylic acid

Sorbic acid and sorbates

Paraoxybenz 0 a t e s ( p arabens) Parachlorometacreosol

0.2 (1.0) 0.1 (0.1)

CH^CH = CHCH = CHCOOH

Dehydroacetic acid and dehydroacetates

T^COCHs 0

HO-/~VcOOR

Effective in conditions

acidic

Pungent smell

0.5

Effective at pH 5 and below

0.5

Not readily affected by organic substances

1.0

Effective over wide pH range. Inactivated by non-ionic surfactants

HO 0.5

Cl-/~\-CH3 OH HO

CI

CI

Hexachlorophene

0.1 CI

Borax

acidic

0.2

Or°"

Carbolic acid

Effective in conditions 1.0

a"

Salicylates

Characteristics

0.2

Cr™"'

Benzoates

Stipulated maximum eoncentration{%)

CI

CI

Inactivated by non -ionic surfactants

CI

Na2B407 • I O H 2 O

0.76

HO Resorcin

Isopropylmethylphenol

Orthophenylphenol

P^'

CH3

HO-ZV-CH'^ ^ = /

\ H 3

0.1* (1.0)

Poor solubility

0.1

Peculiar smell

OH ^ _ , ^

CHa Benzalkonium chloride

0.1

^ O H

-CH=< -Nv NV H . I

Phenoxyethanol

Trichlorohydroxydiphenylether (Triclosan)

V-Cl

, ^CH3

OCH2CH2OH

-Cl

ClCI

OH

*Excluding rinse-off products like soap and shampoo ( ) Rinse-off products The Comprehensive Licensing Standards of Cosmetics by Category (1994)

Preservation of cosmetics 205 Table 9.3. Restrictions on the use of antimicrobial agents in cosmetics Agent

Dates

Trichlorosalicylanilide (TCSA)

1960—62

Tribromosalicylanilide (TBS)

Problems

Nature of restriction No experience of use (Japan)

Photo-contact dermatitis (UK, US)

1962-

0.05% max.

Photo-contact dermatitis

Mercury compounds

9/6/62

Use prohibited (quasi-drug prodSkin ucts) (Notice) (excepting mercuric tion chloride)

Formalin

9/6/62

As above (Notice)

;;

Mercuric chloride

7/23/69

Use prohibited (ethical drugs*, quasi -drug products)

;;

Bithionol

4/4/70

Use prohibited (ethical drugs, etc.) (Notification)

Boric acid/borax

3/12/71

Self-restraint (quasi-drug products, etc.) (Notice) (The use of borax is Toxicity due to percutaneacceptable up to a maximum of 0. ous absorption 76% when its purpose is emulsifying beeswax)

Dichlorophen

1/12/72

Use prohibited (cosmetics) (Notification)

Photo-hypersensitivity

Hexachlorophene

3/2/72

Prohibited for use in bath preparations, talcum powders, and in deodorants (quasi-drug products) • • • a maximum of 0.4% (Notice)

Brain disorders at maximum dosage Toxicity due to percutaneous absorption

Halogenated salicylanilide (Tribromsalan ( T B S ) , Dibromsalan (DBS), Metabromsalan(MBS))

1/26/75

Use prohibited (ethical drugs, etc.) (Notice)

Photo-hypersensitivity

Hydrogen peroxide

4/1/83

Use prohibited

Mutagenicity

disorders,

sensitiza-

Photo-hypersensitivity

Excluding those taken under the supervision of a doctor (The Soc. Cosmet. Chem. Japan ed., Saishin Keshohin Kagaku (Japanese)), Yakujinippo, Tokyo, 1988)^^'

9.5. Methods for evaluating the effectiveness of preservatives As there are currently no standards or procedures in the regulations for testing the effectiveness of preservatives included in cosmetics to prevent secondary contamination, in Japan each cosmetics company carries out such testing individually on the basis of the US Pharmacopoeia. A detailed description of the procedures is given in Cosmetic and Drug Preservation Principles and Practice^^) and the recently published Antibacterial & Antifungal Handbooks^) edited by the Japan Antibacterial and Antifungal Society.

206

New cosmetic science

As cosmetics are mixtures of so many different types of raw material, the preservatives in them are often inactivated. Some of the causes of this are large or small oil polarity, total oil amount^^\ HLB and total amount of non-ionic surfactants^^\ polymer compounds such as thickening agents, film formers and humectants^^'^^^' as well as the plastic^^^ and rubber of containers. It is therefore difficult to predict the effect of a preservative, in view of the ingredients in the cosmetic formula, as well as estimate the amount required; so each product must be tested individually by inoculating it with microorganisms to see if they are killed or not. Thus, if the individual factors affecting the action of a preservative are analyzed and the cosmetic is made to consist of ingredients having little inactivating effect, such as oils with low polarity and surfactants with low HLBs, it is possible to reduce the preservative requirement. On the other hand, if the cosmetic consists of large amounts of ingredients with a strong inactivating effect^^^ such as high polarity oils, high HLB surfactants and polyethylene glycol, it has been shown that the amount of preservative must be increased, as we would expect. Further, among the dihydric glycols used as humectants, such as 1,3-butylene glycol, there are some which have a microbiostasis action against bacteria so if this can be used effectively in combination with the action of preservatives, the amount of preservative may be reduced. The "challenge test" and the "inoculum test" are used to determine if a product will kill microorganisms when it is inoculated with them; their basic details are listed in USP and CFTA guidelines. In these tests, the product is inoculated with Eumycetes (fungi and yeasts), so that there are 1 x 10^ organisms/g in it, or bacteria at a rate of 1 x 10^/g and the result is observed over a period of 1-28 days. Although strains of designated standard microorganisms are used for the tests, in many cases the manufacturer may use also use his own strains taken from products which have been returned by consumers due to contamination. Though it is not possible for such strains to be truly representative of all the microorganisms in our environment, we can assume that products tested by current methods assure a certain degree of quality in cosmetics on the market because they are not being spoiled by microbial contamination. An important task for the future will be to upgrade quality assurance by paying great attention to complaints about products due to contamination. For further details on preservation techniques used in cosmetics and ethical drugs, we refer the reader to Cosmetic and Drug Preservation^^^ which contains much useful information on the principles and practices of the current major preservation techniques and the different types of preservative in use.

9.6. GMP and its validation In 1969, the World Health Organization (WHO) drew up "Good Practices in Manufacture and Quality of Drugs" with the object of ensuring the availability of high quality drugs in order to prevent the serious illness and death caused by inferior quality drugs in the past; and urged member countries to implement them. The purpose of this standard, which is commonly known as GMP^\ is to guarantee that products have adequate quality

Preservation of cosmetics

207

when they reach the market and it covers all aspects from the receipt and storage of raw materials through each stage of the manufacturing process right up to the shipping of the finished product. The prevention of microbial contamination occupies a very important position within GMP. In order to prevent primary contamination, the product should be made in a sanitary environment using hygienic practices and sterilized materials and the containers thoroughly washed or sterilized before filling. Some of the actual means of providing a sanitary manufacturing environment are as follows. (1) Use of filters to remove dust from the ventilation air: each gram of dust may contain anything from one to a million microbes. It is particularly important to remove the large numbers of bacteria and fungi spores because of their great heat resistance. (2) Dehumidify air through air-conditioning: it is essential to dehumidify the air because of the large numbers of Escherichia coli and other gram negative bacteria present in moist air. (3) Provide ultra-clean environment through the use of microbe filters: use HEPA filters to provide a very high degree of cleanliness (near microbe-free environment). (4) Install double doors or positive pressure system to prevent untreated air from the outside coming in. Methods used for ensuring that raw materials are sterile include the following: (1) Water sterilization by means of filters to remove microorganisms (0.22 //m), heat sterilization, ultraviolet sterilization (2) Heat or ethylene oxide sterilization of raw materials (3) Ethylene oxide sterilization of plastic containers It is also necessary to give instruction on clean working practices emphasizing the following: (1) The tremendous numbers of bacteria on the fingers and how to remove them (2) Theory and practice of sterilization methods (drying, UV, chemicals, heat) and points for attention (3) Ways of removing dust and microorganisms from work clothes, shoes, etc. In order to enhance the precision with which GMP is implemented, the new concept of "validation"2i) has been introduced. Validation means that it is not just enough to implement GMP; "the processes and procedures implemented must be designed so that they are appropriate and have a scientific basis and are systematically inspected to see whether they achieve the desired objectives or not". For example, the sterilization of water goes further than simply using heat or UV to kill microbes in it; it also involves constant checks to ensure that the water reaches the required temperature and is maintained at it for the required period of time, that UV lamp output is maintained at the required level and that the irradiation is done for the required period for sterilization, as well as carrying out culture tests at fixed periods to confirm that the water is sterile. Validation also entails keeping records of the results and tracing the cause of problems that occur so that the sterilization conditions may be changed if necessary. GMP and GMP validation are not limited to drugs; they are also a fundamental concept in the quality control of cosmetics and have been helping to raise the quality of cosmetics in Japan since around 199022>.

208

New cosmetic science

References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22.

Sharp, J.: Good Manufacturing Practice: Philosophy and Apphcations, Interpharm Press, 1991. CTFA: Cosmetic J., 4 (3), 25 (1972). Kurata, H., Ishizeki, T. et al\ Microorganism Testing for Drugs and Cosmetics, p. 35, Kodansha, 1978. US Pharmacopoeia XIX USP Convention, Inc. p. 587, 1975. CTFA Technical Guideline, 1975. Henry, S.M.: TGA Cosmetic J., 1 (3), 6 (1969). Gershenfeld, L.: Am. Perfum. Cosmet., 78, 55 (1963). Cosmetic Directive 76/768/EEC Annex VI. Food and Drug Administration: Title 21, Code of Federal Regulations part 700. CTFA: International Cosmetic Ingredient Dictionary 6th edition, 1995. The Comprehensive Licensing Standards of Cosmetics by Category, Yakuji Nippo Ltd., 1994. Keshohin, Kagaku, Kenkyukai Ed., Saishin Keshohin Kagaku (Japanese) J. Soc. Cosmet. Chem. Jpn., Yakuji Nippo Ltd., 1988. Kabara, J. J.: Cosmetic and Drug Preservation: Principles and Practice, Marcel Dekker, New York, 1984. Antibacterial & Antifungal Society of Japan: Antibacterial & Antifungal Handbook, p. 843, Gihodoh, 1986. Bean, H. S.: J. Soc. Cosmet. Chemists 23, 703 (1972). deNavarre, M. G.: J. Soc. Cosmet. Chemists 8, 68 (1957). Patel, N. K. et al\ J. Pharm. Sci. 53, 94 (1964). Bean, H. S. et al\ J. Pharm. Pharmacol. 23, 699 (1971). Macarthy, T. J. et al: Cosmet. Perfum. 88 (5), 43 (1973). Yamaguchi, J. et al: J. Soc. Cosmet. Chemists 33, 297 (1982). FDA: Guideline on General Principles of Process Validation (May 1987). Asaka, Y.: J. Antibacterial Antifungal Agents, Japan 19 (6), 319 (1991).

10 Safety of cosmetics Cosmetics are products used externally to keep the skin clean and healthy. In general, cosmetics are used repeatedly on the skin of healthy people over the long term, and ethical drugs are used to help recovery from illness over a limited period. Thus, cosmetics must be absolutely safe in use in contrast to ethical drugs, the usage benefits of which must be weighed against the risk of side effects. In other words, cosmetics are used by large numbers of people, and the usage basically depends on the users. From this point of view, it is essential that every possibility is taken into consideration to ensure safety. This chapter describes a practical concept of the safety of cosmetics and the basic approaches for ensuring their safety.

10.1. Basic concept of cosmetic safety Cosmetics are composed of various ingredients. Many acceptable components for general use are well documented^-^^ However, useful new compounds, not listed in the references, have been developed as a result of technological progress. The concept of reasonably estimated as safe (REAS); substances reasonably estimated as safe, was accepted for ingredients that have been used for a long time, similar to generally recognized as safe (GRAS), substances generally recognized by experts as safe, for food additives. However, concerns about safety or health problems are changing with the era. Therefore, it has become necessary to reconsider the scientific evaluation of cosmetic ingredients'^'^) as reported in the Cosmetic Ingredient Review^) (CIR) established in 1976 by the Cosmetic, Toiletry and Fragrance Association (CTFA) of the USA. Also, the fragrance components of cosmetics are evaluated for safety by the Research Institute for Fragrance Materials (RIFM) established in 1966, and the research results are disseminated through the scientific journal. Food and Chemical Toxicology (formerly Food and Cosmetic Toxicology). In Japan, the Ministry of Health and Welfare (MHW) presented guidelines entitled "Safety Data Required for Application of Imported Cosmetics and for Manufacturing Cosmetics Containing New Materials" in 1987 to guarantee the safety of new materialsio) (Table 10.1). The need for safety testing is based on the concept that cosmetics are beneficial to human skin only if their safety is confirmed in proper usage. Therefore, the basic strategy for safety assessment of cosmetics is the same as for medical drugs or other chemical substances^'^^\

209

210

New cosmetic science Table 10.1. Safety data required for application of cosmetics containing new raw materials

1. 2. 3. 4. 5. 6. 7. 8. 9.

Test Item

Ingredients

Products

Acute toxicity Primary skin irritation Cumulative skin irritation Sensitization Phototoxicity Photosensitization Eye irritation Mutagenicity Human patcli test

Required Required Required Required Required*"^ Required'^^ Required Required Required

Case by case^^ Not required Not required Not required Not required Not required Required"*^ Not required Required^^

Notes: a) Execute test when LD 50 of target new material is 2 g/kg or less. However, the test is not required when the product is assumed to be safe in consideration of the amounts formulated, b), c ) Not required for material with no UV absorption. d) Not required when irritation responses of cornea and iris are not observed and also chance of exposure to eyes is low. e) Not required for products that are rinsed off. When it is necessary to take great care about toxicity of new materials including bactericides, preservatives, antioxidants, chelating agents, UV absorbents and coal-tar dyes, it may be necessary to add data about subacute toxicity testing, chronic toxicity testing, reproductive toxicity testing, absorption, distribution, metabolism and excretion testing, etc.

10.2. Safety test items and evaluation method The basic concept of the guidelines described above is based on the fact that cosmetics are used for long periods on the skin; it is necessary to confirm that cosmetics do not cause any irritations and toxic responses soon after use, as well as irritation, toxic and allergic responses due to repeated use in the long term. Although it is necessary to confirm the final safety using human volunteers, in many cases various animal models are used as screening tests. 10.2.1. Skin irritation In confirming the safety of cosmetics, the first important point is that cosmetics must not cause any contact dermatitis (rash) when applied to the skin. The cause of contact dermatitis is not always due to cosmetic ingredients. Even if the safety of cosmetics is verified, it is known that environmental conditions such as temperature and humidity when the cosmetic is used, misuse by the consumer, and the user's constitution and physical condition may all cause contact dermatitis (Table 10.2). This section describes the typical methods for guaranteeing the safety of cosmetics to prevent contact dermatitis. Skin irritation is caused by the direct toxicity of chemicals on cells or blood vessels in the skin and is different from contact allergy caused by the immune response described

Safety of cosmetics

211

Table 10.2. Factors influencing skin response 1) Materials 1. Physico-chemical property 2. Purity 3. Solvent (diluent) 4. Concentration 2) Biological factors 1. Genetic factor (species and strains) 2. Sex 3. Age 4. Skin condition 5. Individual variation 3) Environmental conditions 1. Season 2. Temperature and humidity 4) Application and usage 1. Frequency 2. Treatment conditions 3. Period of application and use

later. This type of response is observed in many people when exposed to strong acids or alkalis. Rabbits and guinea pigs have long been used as test animals due to their similar response to that of humans and their high responsiveness. The Draize primary skin irritation test^^'^^'^^) outlined below is often conducted on rabbits. (1) Six or eight rabbits are used. (2) The rabbit's back is clipped free of hair, and the rabbit is held in an animal holder. (3) The test material is applied to two areas on the back. One area is scratched with a sharp instrument such as a hypodermic needle (abraded skin) before the application, and the other area is used untouched (intact skin). (4) The test material (0.5 g or 0.5 ml) is applied to the test area using a 2.5 x 2.5 cm^ patch test plaster. (5) The test material is kept in position for 24 h. (6) After 24 h, the test material is removed and the skin response is evaluated as redness (erythema) and swelling (edema), etc. (7) The skin is re-evaluated after 72 h. The average response index is calculated and the degree of skin irritation is evaluated. Guinea pigs are also used for skin irritation tests since they are easily handled. In the case of guinea pigs, the back or the flank is clipped free of hair, and the test material is applied once or repeatedly to the skin without a patch test plaster. 10,2.2, Sensitization

(allergenicity)

The allergic response may occur when the body is repeatedly exposed to the chemicals with sensitizing potential. If the chemicals are administered via the skin, it is called contact sensitization (contact allergenicity). The sensitization response differs from irritation, which is a local reaction. Since the elicitation is mediated by T-lymphocytes derived from the thymus, contact sensitization is categorized as a cellular immunity compared to humoral immunity such as asthma or anaphylactic shock caused by antibodies. Contact sensitization is also classified as a delayed-type hypersensitivity because the inflammatory reaction is often delayed. The sensitization test is an important test item in evaluating the safety of cosmetics used over the long term. At the immunology research stage, the mouse is often used as the test animal, but the guinea pig is generally used to test cosmetics and their ingredients. The maximization test^^'^^) is commonly used due to its high sensitivity. The procedure is divided into two

212

New cosmetic science

Stages: induction and challenge. In the induction stage, first, emulsified Freund's complete adjuvant (FCA; a mixture of heat-treated tuberculosis bacteria, liquid paraffin and a surfactant) is injected intradermally into the shaved dorsal skin followed by the test material, and an emulsion of the test material and the same amount of FCA. One week later, the test material is occlusively applied percutaneously after treatment with sodium lauryl sulfate in order to boost the sensitization. In the challenge stage 2 weeks later, the test material is applied to the shaved back of the test animal and the sensitization is evaluated based on the skin response 24 and 48 h later. Although the maximization test has high sensitivity, it is occasionally criticized because it is sometimes not easy to emulsify the test material with FCA, especially final products, and intradermal injection may not represent the risk of real use. In this case, the adjuvant and patch test method^^\ which retains high sensitivity, can be used to evaluate the final products using percutaneous application of the test material. Also, other non-FCA methods, such as Buehler's method^^^ and the open epicutaneous test^^'^^^ are useful. Some of the impurities in coloring agents, preservatives and fragrance material have been reported as allergenic materials and it is extremely important to perform sufficient testing at the developmental stage on compounds expected to have special biological effects. 10.2.3.

Phototoxicity

Some chemicals cause a skin irritation response only in the presence of light. These types of materials are called phototoxic materials. A typical example is bergapten (5-methoxysoralen) found in bergamot oil, a fragrance material, which causes Berlock dermatitis. When the fragrances containing these types of compound are applied and then exposed to sunlight, erythema is observed at some parts and, moreover, brown pigmentation may be observed. In screening these types of materials, it is best to use sunlight as the light source, but in actuality, sunlight varies greatly in energy and wavelength distributions depending on the season and time of day. Consequently, phototoxicity testing often uses a xenon arc lamp or a commercial black lamp. Since the wavelength band causing the inflammation response varies with the material, it is important to select the appropriate light source. Generally, materials that have an absorption band in the UV region are tested. Therefore, long-wavelength UV light (UVA) or mid-wavelength UV light (UVB) at a non-erythema dose rate is generally used. Both guinea pigs and rabbits are used as test animals^^'^^^ The test material is applied to the clipped back skin of the animal and the phototoxicity is evaluated as the difference between the response of the part with light exposure and that without light exposure. 10.2.4. Photosensitization

(photoallergenicity)

Photosensitization is an allergic response observed only in the presence of light. Photoallergenicity has been reported for a number of types of materials including UV absorbents, bactericides, and fragrances. It is most important to verify that neither cosmetic products nor their ingredients are photoallergenic since cosmetic products on skin are

Safety of cosmetics 213

commonly exposed to sunlight in daily life. In particular, it is essential to evaluate the photoallergenicity of sunscreen products and UV absorbents which are usually used in the presence of strong UV light. Although the response mechanism of photosensitization is not clearly understood, it is believed that the process involves: (1) activation of the material by light, (2) changes in the cellular functions of the immune system, and (3) changes in the interaction between the material and cells of the immune system, etc. Mice and guinea pigs are often used as test animals^^'^^'^^-^^^ In either case, as in contact sensitivity testing, the procedure involves two stages: a photosensitization induction stage in which the chemical-treated skin is exposed to light, and a photosensitization challenge stage involving application of the test chemical and exposure to light after a certain period from the induction. The skin reaction of the light exposed and unexposed areas in the photosensitization challenge stage is monitored, and the photosensitization is evaluated as the difference in the response degree between the two areas. The results are compared with that of phototoxicity testing to confirm that the skin reaction is not due to photoirritation. 10.2.5. Eye irritation Cosmetics, especially those used on the face and around the eyes such as eye-shadows or mascaras, and hair-care products like shampoos, etc., may enter the eyes during use. Consequently, it is essential to confirm their safety with respect to eye irritation potential. The Draize method^^^ has long been used for this purpose. The test material is applied to one eye of a test rabbit and the response of cornea, iris and conjunctiva is observed over a certain time. In the original method, the response at 2 and 4 s exposure is also evaluated after washing out the test substance with water. It is important to thoroughly consider the risk assessment especially for products that may cause a strong response, such as shampoos containing surfactants with high cleansing power, products containing large amounts of organic solvents such as some hair styling preparations, and oxidation hair dyes. However, the eye irritation caused by many cosmetics such as regular creams, milky lotions and foundations is usually very low. 10.2.6.

Toxicity

10.2.6.1. Acute toxicity This type of testing is necessary to investigate the dangers of accidental ingestion of cosmetics by children and the systemic toxicity, as well as the kind of action to take should this happen. In this case, an oral toxicity test is carried out assuming the actual situation. The test substance is administered to a rodent such as a mouse or a rat using a stomach tube and the degree of toxicity is evaluated from the lethal dose, pathological investigation and general clinical observation. Formerly, the dose causing a 50% death rate in the animals (LD50; LD = lethal dose)^^) was calculated. Recently, from the view point of animal welfare, only a small number of animals are used and an approximate death rate is calculated^'^'^^. Test materials are administered orally, transdermally, subcutaneously and peritoneally for evaluation of the systemic toxicity as a single dose. Aerosols and powders are also

214 New cosmetic science

administered by inhalation, and the systemic acute toxicity is evaluated focusing on the respiratory system. 10.2.6.2. Subacute and chronic toxicity This type of testing is used to investigate the systemic effects, including the effects on the organs, of long-term and continuous use of cosmetics on the skin. Typical test animals are rodents and rabbits. Subacute and chronic toxicity are evaluated over 4 weeks to 3 months, and 6 months to 2 years test periods of, respectively. Generally, various parameters such as changes in feed intake, body weight and growth are monitored and blood chemistry and biochemical testing are carried out during the test. At the end of the test period, each organ is weighed and examined histopathologically, and the effect on the whole body including the special effect on specific organs is determined. 10.2.7.

Mutagenicity

This type of testing is used to investigate materials inducing mutations. Such materials may conceivably affect the incidence of inheritable diseases in man. It has been confirmed that many materials that cause cancer have mutagenic activity and many of the mutagenicity tests investigate materials for both mutagenic and carcinogenic activity. The relevant recommendations from the later review of the OECD guidelines (OECD 1994) and the 1993 International Workshop on Standardization of Genotoxicity Test Procedures (Mutation Research No 312(3) 1994) were taken into account in drawing up guidelines. 10.2.7.1. Reverse mutation test in bacteria^^^ Salmonella typhimurium, and Escherichia coli are often used as the test bacteria for the reverse mutation test. The test involves calculating the number of revertant colonies induced by the test material. 10.2.7.2. Chromosomal aberration test with mammalian cells in culture^'^^ Primary or established cell lines such as V79 Chinese hamster cells and Chinese hamster lung fibroblasts cells are usually used. The evaluation is performed by counting the number of cells in which structural chromosomal aberration or polyploid appear. 10.2.7.3. Micronucleus test with rodents^^"^ Mice are normally used in the micronucleus test. The test material is evaluated from the number of micronuclei in the polychromatic erythrocytes of the bone marrow from tested animals. The tests in Sections 10.2.7.1 and 10.2.7.2 are also performed under the influence of metabolic activity in vivo, which may cause the chemicals to be mutagenic. 10.2.8. Reproductive toxicity^^^ This type of testing is used to evaluate whether or not the chemicals have toxic effects on reproduction, for example on the in utero fetus, to examine the dangers of the test material to the reproductive process. In animal experiments, the period from preconcep-

Safety of cosmetics

215

tion to the end of lactation is divided into three parts, and the test is carried out for each period. Test materials are administered (1) prior to and in the early stages of pregnancy, (2) during the period of organogenesis and (3) during the perinatal and lactation periods. In most cases, rodents and rabbits are used as test animals. However, cosmetic materials are not commonly subjected to this test. 10.2.9. Absorption, distribution^ metabolism, excretion^^^ Cosmetics and their ingredients are defined as materials that have only a mild action on the human body. Nevertheless, it is important to know the possible effect of cosmetic ingredients on the body after percutaneous absorption in order to understand the mechanisms of irritation or toxicity as well as to obtain information regarding evaluation and prediction of safety of ingredients. The distribution in each organ of the body is examined using radiolabeled compounds on test animals. Also, the concentrations in the blood and urine are measured, and the metabolites are analyzed. In order to test the percutaneous absorption by a simple method, a small sheet of skin excised from a test animal mounted on a diffusion cell is generally used. 10.2.10. Testing on humans (patch test, usage testp^^ Clearly-discernible responses such as rashes, erythema, edema, pimples as well as invisible irritation responses such as itching, burning and stinging have been reported as a result of application of cosmetics. The visible response can be predicted to some degree from the results of safety tests previously described. However, before the product is launched on the market, it is very important to confirm its safety under the conditions of expected normal use and of reasonably foreseeable exaggerated use which might have been missed in the previous evaluation. In particular, it is very difficult to predict the risk of sensory responses such as burning, stinging and itching by using animal tests. Thus, a patch test and a stinging test on human volunteers with high sensitivity and a use test under normal conditions are required. However, such tests must be conducted in an ethical manner. 10.2.10.1. Patch tests To verify that a newly-developed material or products containing the material do not cause skin inflammation, a prophetic patch test is performed on the forearm or back of subjects. This patch test is different from that used by a dermatologist to diagnose the causes of dermatitis. The patch test is generally occlusive with plaster made for special use, but highly-volatile materials are applied in the open manner. The materials are usually applied for 24 h, and the skin reaction is evaluated by eye. 10.2.10.2. Controlled-use tests It is impossible to simulate all the conditions under which people use cosmetics by performing various animal and alternative tests. Thus, controlled-use tests are carried out to evaluate the safety of cosmetics in development when they are used under the recommended conditions. For example, environmental conditions such as temperature, humid-

216

New cosmetic science

ity and UV light, as well as the effect of perspiration are important for sunscreen products. For skin-care products, the skin reaction is observed in relation to skin conditions such as dryness and the amount of skin surface lipids. 10.2.10.3. Other tests The possible occurrence of contact sensitivity and acne are also investigated using the skin on volunteers' arms and backs.

10.3. Animal test alternatives A variety of animals and test methods are used in testing the safety of cosmetics for humans but, in recent years, such testing has become the focus of some criticism. To allay this criticism, efforts should be made to observe what are known as the three Rs: "replacement", the testing without animals should be actively developed and should be applied to an actual safety evaluation in order to meet the demands of society; "reduction", using as few animal's as possible and shortening testing times when animal testing must be carried out; and "refinement", improving tests to minimize the animal's pain and get the maximum information. Ideally, alternative test methods should be based on a reaction mechanisms and should be scientifically sound. A number of countries started making efforts to develop alternatives to animal testing relatively early. The Foundation for the Replacement of Animals in Medical Experiments (FRAME) was established in the UK in 1973 with this purpose in mind and in the USA, financial support from the cosmetics industry was used to organize courses on the subject and set up Center for Alternatives to Animal Testing (CAAT) at Johns Hopkins University in 1981. In Japan, the Japanese Society of Alternatives to Animal Experiments was set up in 1989. Cosmetics companies provide support for the research carried out by such organizations and have developed their own alternative testing methods. These methods are already in use for screening^^'^^^ At present, validation, which is carried out to confirm whether previously reported in vitro testing methods can be applied to practical use, is gaining ground. In Europe, The European Center for the Validation of Alternative Methods (ECVAM) was established in 1991 and has been carrying out validation particularly for alternatives to animal-based eye irritation and phototoxicity testing^^^s). Validation is also conducted by the European Cosmetic Toiletry and Perfumery Association (COLIPA) and the Cosmetic, Toiletry and Fragrance Association (CTFA) in the US. In Japan, the MHW project team organized in 1991 to look into the feasibility of using alternatives to eye irritation testing using animals is currently conducting a validation^^). The Japanese Society of Alternatives to Animal Experiments also conducts a validations^). Further, the Japan Cosmetic Industry Association (JCIA) is giving its full support to the MHW project and some of the cosmetic companies in JCIA individually provide assistance to the Japanese Society of Alternatives to Animal Experiments in the validation project. Animal test alternatives should see further development in the future as a new way of evaluating safety.

Safety of cosmetics 217

References 1. Pharmaceuticals and Cosmetics Division, Pharmaceutical Affairs Bureau, Japanese Ministry of Health and Welfare: Supervision: The Japanese Standards of Cosmetic Ingredients, 2nd edn. Yakuji Nippo Ltd., 1985. 2. Society of Japanese Pharmacopeia: Supplement I—The Japanese Standards of Cosmetic Ingredients, 2nd edn., Yakuji Nippo Ltd., 1986. 3. Pharmaceuticals and Cosmetics Division, Pharmaceutical Affairs Bureau, Japanese Ministry of Health and Welfare: Supervision: Supplement II. The Japanese Standards of Cosmetic Ingredients, 2nd edn., Yakuji Nippo Ltd., 1992. 4. Wenninger, J. A.: International Cosmetic Ingredient Dictionary 6th edn., Cosmetic, Toiletry and Fragrance Association 1995. 5. Wenninger, J. A. ed.: International Cosmetic Ingredient Handbook, 3rd edn., Cosmetic, Toiletry and Fragrance Association, 1995. 6. Council Directive 76/768/EEC of 27 July 1967, On the Approximation of the Law of the Member States relating to Cosmetic Products by the Council of the European Communities. 7. Van Den Heuvel, M. J., Clark, D. G., Fielder, R. T. et al.\ The International Validation of a fixed-dose Procedure as an Alternative to the classical LD50 test. Food Chem. Toxicol., 28, 469 (1990). 8. Pharmaceuticals and Cosmetics Division, Pharmaceutical Affairs Bureau, Japanese Ministry of Health and Welfare: Supervision: Japanese Guidehnes for Nonclinical Studies of Drugs Manual, 1995. 9. C I R Cosmetic Ingredient Review 1993 Annual Report, 1993. 10. Pharmaceuticals and Cosmetics Division, Pharmaceutical Affairs Bureau, Japanese Ministry of Health and Welfare: Supervision: The Comprehensive Licensing Standards of Cosmetics by Category, Yakuji Nippo Ltd., 1994. 11. Draize, J. H.: The Appraisal of Chemicals in Foods, Drugs and Cosmetics, Association of Food and Drug Officials of the United States, 1959. 12. Federal Register: Method of Testing Primary Irritation Substances, 38 (187), 1500, 41, September 27 (1973). 13. Federal Register: Primary Dermal Irritation Study, 43 (163) 81-5, August 22 (1978). 14. Magnusson, B., Kligman, A. M.: J. Invest. Dermatol., 52, 268-276 (1969). 15. Magnusson, B., Kligman, A. M.: Allergic Contact Dermatitis in the Guinea Pig; Identification of Contact Allergens, C.C. Thomas, Springfield, Illinois, 1970. 16. Sato, Y., Katsumura, Y., Ichikawa, H., Kobayashi, T., Kozuka, T., et ai: Contact Dermatitis, 7, 225-237 (1981). 17. Buehler, E. V.: Arch. Dermatol., 91, 171-175 (1965). 18. Klecak, G., Geleick, H., Frey, J. R.: J. Soc. Cosmet. Chem., 28, 53-64 (1977). 19. Maurer, T.: Contact and Photocontact Allergens; A Manual of Predictive Test Methods, Marcel Dekker, 1983. 20. Fitzpatrick, T. B., et al. eds.: Sunlight and Man, pp. 529-557, University of Tokyo Press, 1974. 21. Stott, C. W., Stasse, J., Bonomo, R. Campbell, A. H.: J. Invest. Dermatol., 55, 335-338 (1970). 22. Vinson, L. J., Borselli, V. F.: J. Soc. Cosmet. Chem., 17, 123-130 (1966). 23. Haber, L. C , Targovnik, S. E., Baer, R. L.: Arch. Dermatol., 96, 646-653 (1967). 24. Ichikawa, H., Armstrong, R. B. Haber, L. C : J. Invest. Dermatol., 75, 498-501 (1981). 25. Jordan, W. P.: Contact Dermatitis, 8, 109-116 (1982). 26. Council Directive 79/S31/EEC, Amending for the sixth time Council Directive 67/548/EEC on the approximation of laws, regulations and administrative provisions relating to the classification, packaging and labeling of dangerous substances, Official J. European Comm., No. L196, p. 1, 1967. 27. Annex to Commission Directive 92/69/EEC, 31 July 1992, Adapting to technical progress for the seventeenth time Council Directive 67/548/EEC on the Approximation of Laws, Regulations and Administrative Provisions relating to the Classification, Packaging and Labeling of Dangerous Substances, Official J. European Comm. No. L383A, Vol. 35, p. 1,1992. 28. Commission Directive 87/302/EEC, 18 November 1987, Adapting to technical progress for the ninth time Council Directive 67/548/EEC on the Approximation of Laws, Regulations and Administrative Provisions relating to the Classification, Packaging and Labehng of Dangerous Substances, Official J. European Comm., No. LI33, Vol. 31, p. 1, 1988. 29. Goldberg, A. ed.: Alternative Methods in Toxicology, Vol. 1, Mary Ann Liebert, 1983. 30. Loprieno, N., Alternative Methodologies for the Safety Evaluation of Chemicals in the Cosmetic Industry, CRC Press, 1995. 31. Hatao, M., Itagaki, H., Kobayashi, T and Ozawa, T.: Environ. Dermatol, 3, suppl.l, 103-118 (1996). 32. Balls, M., Botham, P.A., Bruner, L.H., Spielmann, H.: In vitro Toxicol., 9, 871-929 (1995). 33. Spielmann, H., Lovell, W.W., Holzle, E., Johnson, B.E. et ai: ATLA, 22, 314-348 (1994). 34. Ohno, Y., Kaneko, T., Kobayashi, T., Inoue, T., Kuroiwa, Y., Yoshida, T. et ai: In Vitro Toxicol., 7, 89-94 (1994). 35. Ohno, T., Itagaki, H., Tanaka, N., and Ohno, H.: In vitro Toxicol., 9, 571-576 (1995).

11 Usefulness of cosmetics

11.1. Usefulness of cosmetics Concerning the four important quality characteristics of cosmetics (safety, stability, usability and usefulness) as described in Outline of Cosmetics, viewing the changes in the characteristics of cosmetics, since the beginning of the 1980s, both safety and usefulness have come to be seen as important and with the development of new raw materials and pharmaceutical agents using life science based biotechnology techniques, new materials from fine chemicals and that of new preparations incorporating them, functional cosmetics with a high degree of usefulness are now being developed. Cosmetics and toiletries have now become such an integral part of our daily lives that we cannot imagine a life without them. Looking at the usefulness of cosmetics in accordance with the parts of the body they are used on (Table 11.1), we can appreciate just how many different kinds of cosmetics are of use to us in our daily lives. For this reason, we must be constantly thinking about usefulness in doing research on cosmetics, in manufacturing and marketing them. This chapter describes the research being done on usefulness giving examples. For details of the usefulness (roles) of products not described here, refer to the relevant chapters in Individual Cosmetics.

11.2. Research on usefulness of cosmetics Research on the usefulness of cosmetics comprises three areas: physiological usefulness, physicochemical usefulness and psychological usefulness. 11.2.1. Physiological

usefulness

Research on physiological usefulness involves that on alleviating skin roughness, preventing hair loss and other physiological aspects of the skin and hair. The core of such research is based on dermatology, physiology, biochemistry, pharmacology, molecular biology, immunology and other life sciences. As our society is rapidly aging, this is one of the most important areas of research.

218

Usefulness of cosmetics

219

Table 11.1. Usefulness of cosmetics

1. Hair

2. Face

Preventing balding

Hair growth promoter

Coloring hair (to look younger, smarter or more fashionable)

Hair color

Preventing hair condition

Hair treatment (split hair coating lotion, etc.)

damage, improving

4. Whole body

hair

Cleansing (physiological, sanitary)

Shampoo, Rinse

Hair styling

Hair styling lotion

Cleansing (physiological, sanitary)

Face cleansers

Preventing skin roughness, improving skin condition

Creams, Milky lotions, etc.

Alleviating liver spots

Whitening cosmetics

Alleviating wrinkles

Face treatment

Beautifying (color effect)

3. Body

Cosmetics

Usefulness

Where used

effect,

psychological

lotion. Permanent

waving

Makeup products

Preventing dental decay, bad breath

Dentifrice, Mouth wash

Alleviating acne

Acne products

Cleansing (physiological, sanitary)

Soap, Body shampoo

Sunscreening

Sun care products (sunscreens, etc.)

Preventing body odor (armpits, feet)

Deodorant products

Bleaching, removing hair (unwanted hair)

Bleach, Depilatories

Stimulating circulation (physiology, health)

Bath preparations

Treating rough skin on the hands

Handcare products

Making nails more attractive

Nail enamel, etc.

Making effect)

Perfume, Eau de cologne and other grance products

body

11.2.2. Physicochemical

smell

nice (psychological

usefulness

Examples of research being done tecting the skin from the effects absorbing and scattering agents, freckles, making the hair more which rheology is applied. 11.2.3. Psychological

fra-

on physicochemical usefulness comprises that on proof ultraviolet radiation through the use of ultraviolet effectiveness of makeup in covering liver spots and attractive through permanent waving and creams to

usefulness

In the area of psychological usefulness (aromacology of fragrance, psychology of makeup colors, etc.) the effectiveness of cosmetics in such aspects as the soothing as well as stimulating effect of their fragrance on the mind, giving the wearer more confi-

220

New cosmetic science

Permanent waving lotion Split Hair coating lotion Hair growth promoter

Makeup covering effect

Hair growth promoter

Alleviation of skin roughness

be

o

Skin whitening Wrinkle prevention

Sun care products

Cleansing agents H Deodorants Bath preparations

Psychological effect Skincare Makeup

bo

Fragrance

Fig. 11.1. Research on the usefulness of cosmetics and its effects.

dence and raising working efficiency, is studied. In this area, the results of psychological research and more recently psychoneuroimmunology and other research are being applied. The research being done in the three areas above and its effects are illustrated in Fig. 11.1.

11.3. Examples of usefulness research 11.3.1. Examples of research on physiological

usefulness

11.3.1.1. Alleviation of skin roughness^^^^ For the purpose of moisturizing the skin, the water-humectant-oil balance is extremely important and these three components exhibit complementary functions in this respect. Research has shown that a cream with a proper water-humectant-oil balance not only improves the skin surface condition but also the physiological condition of the parts under it. Let us look at the procedures and results of this research. The cream used in the research was an 0/W type with a proper balance of oily ingredients comprising hydrocarbon compounds with squalane as the main one and humec-

UsefuIness of cosmetics

221

o

Cream not applied

Cream applied

Fig. 11.2. Improvement in skin surface condition due to cream.

tants which were polymer ones such as hyaluronic acid, and polyol ones such as glycerin and 1,3 butylene glycol which are much used in cosmetics. The cream was given to a panel of 25-35 year old male volunteers (group I) to apply to their cheeks for a period of 2 weeks during the coldest part of the winter in February. For comparison an O/W type cream containing three ingredients in unbalanced proporSurface condition

c "o

E 2

(3

Mir Before After Before After Part with Part with no cream cream Group I

JL

_L

1

Before After Before After Part with Part with no cream cream Group II

Fig. 11.3. Improvement in skin surface condition due to cream.

222 New cosmetic science TWL

1.4

1II

-

1.2

o cu

1 0

C/2

08

^

L-, dJ




< Reheat/cool lower part < Final cooling >

1 \JJ

kf

[Fill

\ \ Hot blast \ "^

^

"c5 11

—

u

7T,

UT7

tt )tbl ast 1

[J-^givtL] [m

I Pinhole prevention!

y "" Ak

y

1w

^

W tt [Cold blast 1

-«•-

w

w

\

[Col dbl ast|

[Contraction hole prevention | [Easing mold release] Fig. 15.10. EJ molding method.

u

Cosmetic manufacturing equipment 289

Fig. 15.11. Automatic lipstick molding machine (Yoshino Kogyosho Co., Ltd.).

the molded lipstick is inserted into the container and flaming is carried out to bring out its luster. 15.6.1.2. Ogive capsule molding machines This type of equipment was developed as an automatic molding machine. In its molding process, the molten lipstick is poured into an ogive made from a resin or a casing known as a capsule. The best known molding method is the Ejectlet (EJ) method developed by the British company Ejectlet. It is shown diagrammatically in Fig. 15.10. The molding machine has several holders mounted on its chain conveyor into which the containers are put inverted and the chain conveyor operates intermittently to move the containers through each stage of the molding process. This method enables the molding of lipstick to be automated and can be used for its mass production. However, the temperature and time conditions for each molding process must be set very accurately to suit different lipstick formulae and actually have a great influence on lipstick moldability. Fig. 15.11 is a photograph of this type of automatic molding machine. 15.6.2. Foundation molding machines Nowadays, most powder cosmetics are molded using automatic pressing machines. These are turntable-type machines in which metal dishes are fed automatically to the press concave mold attached to a rotating disc by the parts feeder. The dish is then rotated to the next position at which a fixed amount of powder comes into it from a hopper. At the next position, the powder is pressed into the dish using a fixed pressure (hydraulic) and a mold suited to the dish; then the molded product is removed. After-

290

New cosmetic science

® Cam rTn

Nylon material \ ^Pressing paper

Metal mold

_Powder into dish

pzzzz]

Inner dish

Hydraulic cylinder

n

Fig. 15.12. Molding process for powder cosmetics.

wards, the mold is cleaned automatically and again fed to a dish. This continuous process is shown in Fig. 15.12. The molded product then goes to an automatic cleaning machine to have powder adhering to its periphery removed and is then put into the final container. Fig. 15.13 shows one of these molding machines.

r ^''

Fig. 15.13. Automatic powder molding machine (Mizuho AP-3).

Cosmetic manufacturing equipment 291

For this type of molding, the pressing conditions are very important so it is necessary to adjust the pressure and number of pressings in accordance with powder characteristics. For instance, in the case of mica and other pearlescent powders, as it is difficult to remove air and compact the powder, the pressing may be done in stages or the pressure varied during one press. Sometimes, however, due to the shape of the dish, it may only be the periphery of the molded product which is hardened. This problem can be solved by adjusting the density distribution of the powder in the dish before pressing or changing the shape of the pressing mold, which makes the hardness uniform.

15.7. Filling and packaging machines The type of filling machine used for cosmetics depends on the state of the material to be filled, the type of container and volume of the contents, and there are many different types. Bottle filling machines are used for lotions and milky lotions, wide-neck bottle or tube filling machines for creams, cardboard drum and bag filling machines for powders (the filling of aerosol containers is described in Chapter 13). A detailed explanation of filling machines will not be given here because of their tremendous variety but their common requirements are accuracy in measuring the amount to be filled, high speed and ease of cleaning. Further, the filling operation must be done in a clean and sanitary environment. In this respect, the filling of eyeliners and mascaras is done in a clean room in order to prevent contamination by microorganisms in the liquid state. In the packaging and finishing processes, labeling machines, printing machines, cartoning machines and weight checking machines are used. The performance of labeling machines has been raised through advances made in the development of adhesives and label papers. Inkjet printers are now much used for the printing of manufacturing codes, etc. Cartoners and robots are used to achieve manpower savings when packing products into cases and cartons.

References 1. Inspection and Guidance Division, Pharmaceutical Affairs Bureau, Ministry of Health and Welfare ed.: GMP for Cosmetics, Yakuji Nippo Ltd., 1988. 2. Kubo, K., Mizuwatari, A. et al: Powder Theory and Applications of Powders, p. 425, Maruzen, 1962. 3. litani, K., Arakawa, M. et al. eds.: Physical Properties of Powders and Engineering (Chemistry Supplement 31), p. 55, Kagaku Dojin, 1967. 4. Shimizu, Ota: Application of New Mixing Technology, p. 301, Technical Information Association, 1989. 5. Hashimoto, T.: Mixing and Kneading Equipment, General Science and Technology Research Institute, 1986. 6. Endo, K., Shikamata, K., Kobayashi, J., Hosaka, H.: Manufacturing Process Charts for Food Supplements, p. 697, Kagaku Kogyosha (Chemical Industries Co., Ltd.), 1989.

16 Regulations on cosmetics Although cosmetics are become more and more closely involved in our daily lives, expectations of them are growing and society's concerns about them are increasing, still very few people are aware of the large number of regulations governing them and the strictness of the quality assurance under which they are manufactured and sold. As cosmetics are used repeatedly, maximum efforts must be made to ensure their efficacy (effectiveness and usefulness) and safety. The various regulations governing cosmetics can be said to be the minimum required pledge to the consumer of assured and constant quality. The major ways that different countries regulate cosmetics are by approval and reporting systems, and by obliging companies to provide certain information on cosmetic container labels or to keep in-house records; or there may be no particular regulations at all. Countries in Asia have adopted license and approval systems while America and many countries in Europe have adopted reporting systems. Furthermore, the definition of cosmetics differs from country to country and, depending on their ingredients, they may sometimes come under the classifications of "cosmetic incorporating pharmaceutical agent", "OTC product" or "ethical drug". For this reason it is necessary to make a thorough study of the regulations in each country. Notwithstanding any variations in the regulatory systems in different countries, it is still the responsibility of the manufacturer to guarantee the quality of his products which also includes a guarantee of their safety. Moreover, as the regulations may change, it is necessary to carefully study the latest ones regarding the manufacture and sale of cosmetics.

16.1. Regulations concerning cosmetics in Japan In Japan an approvals system is in force. There are many types of regulation governing the manufacture and sale of cosmetics and as cosmetics are used on the human body on a daily basis, stipulations regarding their quality, efficacy and safety are made in the Japan's Pharmaceutical Affairs Law^^ (Law No. 145, 1960). This law, which concerns peoples' health, sets forth regulations regarding the quality, efficacy, safety and proper use of drugs, quasi-drugs, cosmetics and medical devices, and plays a very important role in improving the health of the Japanese people and ensuring they can live healthy lives.

292

General provisions Purpose Definitions

1

-Pharmaceutical Affairs Councils ---Central and regional pharmaceutical affairs council-related regulations Pharmacies Permission to establish a pharmacy, approval standards, control duties of controller

Prohibition of exaggerated advertising Prohibition of advertising of drugs, etc. before approval

Japanese Pharmacopeia Standards for ethical drugs, etc. Regulations on drugs Regulations on quasi drugs Items to be indicated on the immediate container, etc Regulations on cosmetics Items to be indicated on the immediate container. etc (Name of manufacturer or importer, name of product, etc. set forth in Ministl-y of Health and Welfare ( M H W ) ordinances supplementary to those mentioned in preceding items) Applic;ible items (Articles 51, 53 57) I'rohibitivn of manufacture, sale, etc. PI-ohibition of exaggerated claims / ,

I

Licensing of manufacturers and importers of drugs, quasi drugs, cosmetics, niedical devices Licensing standards Licenses granted by Governor of the pt-efecture in which the factory (importing office) is located Approval to manufacture (import) drugs, quasi drugs, cosmetics, etc. granted by the hlinister of Health and Welfare (MHU')

I

.

Licensing for sellers of drugs, quasi-drugs and medical devices

I Quality Standards of Cosmetics MFILY Notification No. 322 (standards established on the basis of Article 42 of the Pharn~aceuticalAffairs Law) Ordinal-y cosmetics (prohibited ingredients, Japanese Standards of Cosmetic Ingredients (JSCI), etc.) Special cosmetic products (hormones, antihistamines, etc.) Japanese Standards of Cosmetic Ingredients (JSCI) 1991 : total 592 items 1967 : 114 items established 1970 : 91 items added 1973 : 227 items added, 1 item delated 1982 : 107 items added, 15 items deleted 1985 : 63 items added 1991 : 22 items added. 16 items deleted

Supervision Spot inspections, etc. Disposal, etc. Improvement orders Cancellation of license, approval, etc. Miscellaneous provisions

I Penal regulations

(

of f'hal-niaceutical Affairs Law

Enforcement Regulations of I'harmaceutical Affairs Law Ministerial ordinances with detailed regulations I '1-2)

Items which may be used in [)rugs, etc. Coal-tar colors specified in " T h e M H W Ordinance Designating Coal tar Colors I'ermitted for Use in L)r~lgs,etc. M H W Ordinance N o . 30. 1966 : N o . 3. 1967 : No. 55. 1972 - -

I

may be used in all drugs, quasi drugs and cosmetics Table I Table I1 may be used in external use dr~tgs,external use q u a s i d r u g s and cosmetics Table 111 may be used in external use drugs, external use q ~ r a s i d r u g sand cosmetics which do not come into contact with rnucous membranes

I : I1 items ; 11 : 47 items ; I11 : 25 itetns (total 83 items) (including lakes)

Fig. 16.1. Japan's Pharmaceutical Affairs Law and related legislation.

I

"

294

New cosmetic

science

16.1.1. Regulations in Pharmaceutical Affairs Law concerning cosmetics and quasi-drug products The following describes the regulations in the Pharmaceutical Affairs Law which concern the cosmetic and quasi-drug products mentioned in this book. 16.1.1.1. Definition of cosmetics In Article 2 of the Pharmaceutical Affairs Law, cosmetics are defined as "items applied to the human body by means of rubbing, sprinkling and the like, for the purpose of cleaning, beautifying, adding to the attractiveness, altering the appearance or keeping the skin or hair in good condition, which should be items with a mild action on the human body". Items having a mild action means those which do not have a strong action on the human body even if misused, and which have high safety. More specifically this means the following: (1) items whose purpose is to cleanse the human body: soap, face cleansing cosmetics, shampoo, cleansing lotion, packs, etc. (2) items whose purpose is to beautify the human body: lipstick, foundation and other makeup cosmetics (3) items whose purpose is to enhance peoples' charm: perfume, eau de Cologne, other fragrance products, lipstick, manicure preparations and other makeup cosmetics (4) items whose purpose is to change the appearance: lipstick, mascara, eye shadow and other makeup cosmetics (5) items whose purpose is to maintain the skin and hair in a healthy condition: creams, milky lotions, lotions, hair rinses, hair tonics, hair sprays, etc. 16.1.1.2. Definition of quasi-drug products Quasi-drug products occupy a position mid-way between that of drugs and cosmetics, and the effects which they claim to have are within the scope permitted in the Pharmaceutical Affairs Law. Their definition is given below. However, more specifically, preparations are defined individually on the basis of an overall assessment of such items as ingredients and their quantities, efficacy, method of use, dosage and product form. In Article 2 of the Japan's Pharmaceutical Affairs Law, "quasi-drugs" are described as items which have the purposes listed in (l)-(5) below, a mild action on the human body, and are not equipment or instruments; and items conforming to this and designated by the Ministry of Health and Welfare: (1) prevention of nausea, other such discomfort, bad breath or body odor (2) prevention of prickly heat, festering and the like (3) prevention of hair loss, hair growth promotion or depilatory action (4) extermination and repulsion of rats, flies, mosquitoes, fleas, etc. to maintain human and animal health (5) items conforming to the above designated by the Ministry of Health and Welfare (a) cotton products intended for sanitary purposes (including items incorporating paper and cotton) (b) items having a mild action on the human body: hair color; permanent waving

Regulations on cosmetics 295

lotion; items which, besides their cosmetic purpose, are used for the prevention of acne, chapping of skin, itchiness, rash, chilblains, etc. or those which have the additional purpose of disinfecting the skin or the oral cavity; bath preparations Some actual quasi-drugs and their effects^) are listed in the following: (1) prevention of nausea, other such discomfort, bad breath: mouth freshener (effect: prevention of nausea, motion sickness, bad breath, etc.) (2) prevention of body odor: deodorants (effect: prevention of armpit and other body odor) (3) prevention of prickly heat, festering and the like: talcum powder (effect: prevention of prickly heat, diaper rash, etc.) (4) prevention of hair loss, hair growth promotion: hair growth promoter, hair tonic (effects: prevent hair loss, dandruff, itchiness; promote hair growth, nourish hair, etc.) (5) items with a depilatory purpose: depilatory (effect: removal of unwanted hair on the arms and legs) (6) items with the purpose of exterminating or repelling rats, flies, mosquitoes, fleas and other pests in order to maintain human and animal health: rodenticide (effect: kills rats, repels house mice); insecticide (effect: kills flies, mosquitoes, fleas and other insects); insect repellent (effect: repels mosquitoes, sandflies and the like). (7) cotton products intended for sanitary purposes: sanitary cotton products, cleansing cotton products, sanitary napkins (8) hair color (including decolorants and dye removers) (9) permanent waving lotions (10) items which, besides their cosmetic purpose, are used for the prevention of acne, chapping of skin, itchiness, rash, chilblains, etc. or those which have the additional purpose of disinfecting the skin or the oral cavity: (a) medicated cosmetics (including medicated soap); (effects: prevention of acne, chapping of skin, chilblains and liver spots and freckles due to sun exposure, etc.). (b) medicated dentifrices (effects: prevention of dental caries, pyorrhea, etc.) (11) bath preparations (effects: alleviation of prickly heat, stiff shoulders, neuralgia, hemorrhoids, etc. 16.1.2. Regulations on manufacture and sale of cosmetics and quasi-drug products In addition to the above definitions, the Pharmaceutical Affairs Law also makes various stipulations with regard to such items as the competence of the manufacturer, structure of his premises and equipment at it, manufacturing/importing approvals for quasi-drug products, cosmetics, labeling on products and advertising in order to ensure that manufacturing and selling are done in the proper manner. In outline, these provisions are as follows: (1) Companies must have the necessary "manufacturing or importing license" for cosmetics or quasi-drug products, (a) A company may receive such a license from the Prefectural Governor if, on

296

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inspection, its competence, structure of the manufacturing premises (or importing office) and equipment at it meet the standards. In the case of cosmetics, if the company wishes to both manufacture and import, a license to manufacture cosmetics is required for each manufacturing location and one for the sale of imported cosmetics for each importing office, (b) It is necessary to apply for a renewal of a manufacturing or importing license every three years. Furthermore, if there are any changes to circumstances for which the license was granted (e.g. changes in company directors, factory structures/equipment) this must be notified within 30 days. (2) "Manufacturing approval" is required for each cosmetic and quasi-drug product to be manufactured and "importing approval" for each such product to be imported. If there are any changes to the approved items, an application must be made for the approval of such changes by the Prefectural Governor. (3) Approval of new ingredients for cosmetics and quasi-drug products is obtained from the Central Pharmaceutical Affairs Council which will examine their safety, efficacy and other aspects. (4) In order to ensure the proper retailing of products, the name and address of the manufacturer or importer, product name, names of ingredients designated by the Minister of Health and Welfare, usage and precautions in use must be displayed on them. (5) In order to prevent drugs and quasi-drugs having a harmful effect on people's health, the Minister of Health and Welfare may establish standards relating to their properties and quality based on recommendations of the Central Pharmaceutical Affairs Council. (6) For cosmetics, it is forbidden to make false statements or exaggerated claims in advertising with regard to such items as manufacturing methods, safety, efficacy and performance. As seen from the foregoing, the Pharmaceutical Affairs Law requires various permissions for each quasi-drug and cosmetic product to be manufactured or imported to ensure that they have the proper quality. They are explained in more detail below. Manufacturing approval for cosmetics may be obtained once an application giving such details as product name, ingredient names, specifications and formulation quantities, manufacturing method and method of use has been made to the Ministry of Health and Welfare, and the product has been screened for safety. As quasi-drug products contain active ingredients, it is necessary to apply for approval of such ingredients with respect to safety and efficacy, as well as for a manufacturing license. In order to apply for such approval, documents giving such details as product name, ingredient names, specifications and formulation quantities, manufacturing method, method of use, indications or effects, product specifications and test results are submitted to the Ministry of Health and Welfare. In the case of cosmetics, the approval of an application takes about 3 months; and, in the case of quasi-drug products, it takes about 6 months. However, in the case of cosmetics, the system is in the process of being simplified and a category approval system^) has now been introduced. Under the category approval system, ingredient lists containing such information as ingredient names, specifications and formulation limits have been published for individual cosmetic categories such as creams, milky lotions and

Regulations on cosmetics 297

foundations. In the case that a cosmetic product consists only of ingredients on the list, if an application for manufacturing or importing approval giving the product name ingredient names and other necessary details is submitted to the Prefectural Government, it is possible to start manufacturing or importing a cosmetic product on the day of submitting the application. It has already been mentioned that the Pharmaceutical Affairs Law contains no more than basic legislation. Consequently, the Ministry of Health and Welfare makes efforts to handle matters relating to it as specific cases, give advice in cases of doubt and issue Notifications concerning related matters. Furthermore, the Japan Cosmetic Industry Association is aiming to ensure that the manufacture of cosmetics and their quality control (cosmetics GMP) is done in the proper manner through the implementation of its own standards in Technical Guidelines for the Manufacturing and Quality Control of Cosmetics^) (Notification No. 57, 1988).

16.2. Laws relating to cosmetics in Japan In order to manufacture or sell cosmetics, the basic law that must be obeyed is the Pharmaceutical Affairs Law. In effect, this means having to know the requirements for ensuring that such cosmetics always have the proper quality, and obeying various other laws relating to them. Some of these laws are listed in Table 16.1. Table 16.1. Laws relating to cosmetics No.

Law

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Pharmaceutical Affairs Law Commodity T a x Law High-pressure Gas Control Act Fire Services Act Basic Law for Consumer Protection Anti-monopoly Law Unfair Competition Prevention Law Patent Law Weights and Measures Act Design Law Utility Model Law Trademark Law Food Sanitation Act Poisonous and Violent Substances Control Law Industrial Standards Act The Law against Unjustifiable Premiums and Misleading Representation Government Monopoly in Alcohol Act Basic Law for Environmental Pollution Control Law Concerning Examination and Regulations of Manufacture, etc. of Chemical Substances Waste Management and Public Cleansing Law

17 18 19 20

Law number

Year enacted

145 48 204 186 78 54 14 121 207 125 123 127 233 303 185 134

1960 1962 1951 1948 1968 1947 1934 1959 1951 1959 1959 1959 1947 1950 1949 1962

No. 32 No. 132 No. 117

1937 1967 1973

No. 137

1970

No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No.

298 New cosmetic science

Cosmetics consist of oil and fat based raw materials, surfactants, colors, fragrances, humectants, antibacterial agents and other constituents. These raw materials are made into cosmetics using emulsification, dispersion, solubilization and other basic techniques, and after being put into containers, packed and inspected, the finished product reaches the consumer through cosmetic shops, department stores, supermarkets and other retail outlets. The various laws relating to raw materials, containers, manufacturing plants, products and marketing activities can therefore be said to be laws that relate to cosmetics. 16.2. L Regulations relating to raw materials The Japanese Standards of Cosmetic Ingredients^— (Notification No. 322, 1967), based on Paragraph 2, Article 42 of the Pharmaceutical Affairs Law, were established to further improve the quality of cosmetics and they have been revised 6 times. In these standards, specifications have been set down for the raw materials normally used in cosmetics to ensure that they are of the proper quality and to make them safer. Six hundred different raw materials are now covered. Other specifications relating to cosmetic raw materials are found in the Japanese Pharmacopoeia (standards for drugs), official raw materials lists in The Japanese Standards of Food Additives, and The Japanese Cosmetic Materials Codex I-VP-^^) (issued between August 1986 and September 1991), prepared as a manual of standards for the raw materials which have already seen use in cosmetics under the supervision of the Pharmaceuticals and Cosmetics Division of the Ministry of Health and Welfare's Pharmaceutical Affairs Bureau. For quasi-drug products. The Japanese Standards of Quasi-drug Ingredients was issued in June 1991. As cosmetics are used on the human body, it is necessary to use the raw materials listed in the standards and specifications as they have sufficiently high quality and high safety. Furthermore, applications for approval of cosmetic products using unlisted raw materials (new ingredients) must be accompanied by safety data and other necessary information. Approval will be given once this information has been examined by the Central Pharmaceutical Affairs Council. Examples of other regulations relating to cosmetics are those in List of Existing Chemical Substances based on the Law Concerning Examination and Regulations of Manufacture of Chemical Substance, the Poisonous and Violent Substances Control Law, and the Government Monopoly in Alcohol Act. 16.2.2. Laws relating to product contents 16.2.2.1. Laws relating to cosmetic products The Quality Standards of Cosmetics^^^^ has been established in 1967 (MHW Notification No. 321, 1967) and it has been revised 7 times since then. In order to prevent cosmetics from having a damaging effect on human health, these standards stipulate ingredients which are prohibited in cosmetics and include formulation standards for cosmetics containing special ingredients (special cosmetic products). Some of the stipulations are as follows:

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299

(a) (1)

Prohibited ingredients Ingredients prohibited in cosmetics under Quality Standards for Cosmetic Products (i) dichlorophene (ii) mercury and mercuric compounds (iii) hydroquinone monobenzylether (iv) bithionol pilocarpine (V) (vi) halogenated salicylic anilide (2) Ingredients prohibited in notifications (Notification 2 No. 321, 1986) (i) antihistaminics other than those of the aminoether type (ii) hormones other than estradiol, estrone and ethinylestradiol (iii) vinyl chloride (monomer) (iv) bismuth compounds other than bismuth oxychloride chloroform (V) (vi) vitamin L] and L2 (vii) local anesthetics such as procaine (viii) formalin (ix) methyl alcohol (x) boric acid, sodium perborate, borax (the use of borax is acceptable when its purpose is emulsifying beeswax or bleached beeswax) (b) Special cosmetic products (1) For cosmetic products containing hormones, the types of hormone (follicle hormones) and their amounts are stipulated. ® The total amount of hormone contained in 1 g of cosmetic products applied to the head, mucous membranes or the oral cavity must not exceed 200 International Units (lU). @ For cosmetic products used on parts other than in ® containing aliphatic lower monohydric alcohols, the total hormone content in 1 g of product must not exceed 200 lU (excluding cosmetic products containing such as alcohols for the exclusive purpose of dissolving their ingredients). @ For cosmetic products other than those in ® and ©, the total hormone content in 1 g of product must not exceed 500 lU. In the table below the number of lU/g have been converted to mg/100 g or 100 ml of product. Follicle Hormones Estradiol Estrone Ethinylestradiol

(2)

® and ®

(D

0.4 mg max. 2.0 mg max. 0.2 mg max.

1.0 mg max. 5.0 mg max. 0.5 mg max.

For cosmetics containing antihistaminics, stipulations are made regarding parts of the body they are used on, the type of antihistaminic and its content: (i) body part: limited to cosmetics used on the head (ii) type: must be aminoether type (iii) content: not more than 0.01 g/100 g of product

300 New cosmetic science Table 16.2. Permitted amounts of benzoic acid, salicylic acid and other pharmaceutical agents in 100 g of a cosmetic product Agent Aluminium chlorohydroxy allantoinate Benzoic acid Benzoates Chlorocresol Salicylic acid Salicylates Phenyl salicylate

(3) (4) (5) (6) (7) (8) (9) (10)

Amount (max. amount) Ig 0.2 g Ig 0.5 g 0.2 g Ig Ig

Agent Sorbic acid and its salts Dehydroacetic acid and its salts Parahydroxybenzoic acid esters Phenol Hexachlorophene Polyoxyethylene lauryl ether (8-^ 10 E. 0.) Resorcin

Amount (max. amount) 0.5 g 0.5 g Ig 0.1 g 0.1 g 2g 0.1 g

Vitamins used in cosmetics must be any other than vitamin Lj or L2. The addition of methyl alcohol is not acceptable. The impurity content of ethanol must be not more than 0.2 ml/100 ml of product. If cosmetics contain benzoic acid, salicylic acid, etc., the amounts per 100 g of product must be not more than those shown in Table 16.2. If cosmetics contain isopropylmethylphenol, etc., the amounts per 100 g of product must be not more than those shown in Table 16.3. However, soaps, shampoos and other rinse-off products are excepted. For cosmetics containing cantharides, ginger or capsicum tinctures, the total included amount must not exceed 1 g per 100 g of product. For cosmetics containing paraamino benzoic acid or its esters the total included amount must not exceed 4 g per 100 g of product. For cosmetics containing thiram, the amounts must not exceed those given below. (i) 0.5 g per 100 g for soap, shampoo and other rinse-off products (ii) 0.3 g per 100 g for cosmetics other than those in (i). Sodium TV-lauroyl sarcosinate may only be contained by cosmetics which are rinsed away immediately after use such as dentifrices, soap and shampoo. The amount in dentifrices must not exceed 0.5 g per 100 g of product. Table 16.3. Permitted amounts of isopropylmethylphenol and other pharmaceutical agents in 100 g of a cosmetic product Agent

Isopropylmethylphenol Benzalkonium chloride Orthophenylphenol Chlorhexidine gluconate Cinoxate Alkylisoquinolinium bromide Trichlorocarbanilide

Amount (max. amount) 0.1 g 0.05 g 0.3 g 0.05 g 5g 0.05 g 0.3 g

Agent

Amount (max. amount)

Zinc paraphenol sulfonate Halocarban 2- ( 2 - h y d r o x y - 5 - m e t h y l p h e n y l )

2"g 0.3 g

benzotriazole 2-hydroxy-4-methoxybenzo-

7g

phenone

5g

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(11) Undecylenic acid monoethanol amide may only be contained by rinse-off products such as soap and shampoo. The above standards have been provided for ingredients contained by particular cosmetics. In addition, the following general requirements also apply. (1) The arsenic content of cosmetics must not exceed lOppm as arsenious acid (Notification No. 81, 1968). Although there is no firm stipulation regarding lead content, the maximum desirable amount is taken as 20-30 ppm. (2) Aerosol cosmetics must conform to the standards regarding the gases which may be used in them such as those in the High-pressure Gas Control Act and Notification No. 742 issued in 1989 which states that they must not contain "Specified Chlorofluorocarbons" (specified chlorofluorocarbons: dichlorodifluoromethane, dichlorotetrafluoroethane, trichloromonofluoromethane). 16.2.2.2. Regulations on quasi-drug products Notification No. 464^) issued in 1962 sets forth standards for the inclusion of the following substances in medicated cosmetics, one of the categories of quasi-drug products. (1) Hormones: the inclusion of hormones in medicated cosmetics is limited to Follicle Hormones (FH) and Adrenocortical Hormones (ACH) and their proportions (total amount in 100 g or 100 ml of product) are as set forth in Tables 16.4 and 16.5. (2) Homosulfamine: not exceeding 1 g per 100 g of product (3) Cantharides tincture: not exceeding 1 ml per 100 g of product (4) The inclusion of the following substances is not permitted, (i) hormones other than those in (1) (ii) sulfanilamide and its derivatives (iii) mercury, mercuric compounds and formalin (iv) vitamin Li and L2 (v) nitrofuran compounds (vi) strontium compounds, selenium compounds, cadmium compounds (vii) antibacterial substances (antibiotics) (5) Other substances whose use is not permitted for use in quasi-drug and other cosmetic products in accordance with notifications issued by the Director of the Pharmaceutical Affairs Bureau, etc. (i) bithionol (ii) vinyl chloride (monomer) (iii) halogenated salicylanilide group antimicrobials (tribromsalan, dibromsalan, metabromsalan, etc.) Table 16.4. Permitted amounts of follicle hormones Follicle Hormones

Used on head, mucous membranes or in oral cavity

Other cases

Estradiol and its esters Estron Ethinylestradiol Other Follicle Hormones

0.8 mg max. 4.0 mg max. 0.4 mg max. 4.0 mg max. as estrone

2.0 mg max. 10.0 mg max. 1.0 mg max. 10.0 mg max. as estrone

302 New cosmetic science Table 16.5. Permitted amounts of adrenocortical hormones Adrenocortical Hormones

All medicated cosmetics

Cortisone and its esters Hydrocortisone and its esters Prednisone Prednisolone

2.5 mg max. 1.6 mg max. 0.61 mg max. 0.5 mg max.

(iv) chloroform (v) bismuth subnitrate (vi) specified chlorofluorocarbons The Standards for Permanent Waving Agents^) (Ministry of Health and Welfare Notification No. 280, 1968) and Standards for Sanitary Napkins^) (Ministry of Health and Welfare Notification No. 285, 1966) are standards for quasi-drug products. Products which require precautions for use to be displayed on them include permanent waving agents, hair color, bleaches and medicated soaps, shampoos, rinses and shaving preparations containing bactericides. 16.2.3. Regulations concerning

containers

This section gives a general description of the regulations governing containers and includes those regulating items displayed on them. The Pharmaceutical Affairs Law and the Fair Competition Codes stipulate items which must be displayed on containers in order to prevent harm due to improper use, etc.. The Fair Competition Codes make stipulations regarding the items displayed on cosmetic products on the basis of Article 10 Item 1 in the Law against Unjustifiable Premiums and Misleading Representation (Law No. 134, 1962). 16.2.3.1. Items in labels displayed on containers or packaging The Pharmaceutical Affairs Law stipulates that the following must be clearly displayed in Japanese on the outside of containers or packaging in a place where they can be easily seen. (1) Name of product (2) "Quasi-drug Product" in the case of a quasi-drug product (3) Name and address of manufacturer or importer (4) Production code or number (5) Contents (weight, volume, number of items, etc.) (6) Names of ingredients when the product contains those designated by the Ministry of Health and Welfare (7) Expiration date (not required when the quality is guaranteed for 3 years or over) The following stipulations concern exceptions to the above regarding the display of ingredients and amount of contents. (1) When ingredients designated by the Ministry of Health and Welfare are displayed on the outer packaging they do not have to be displayed on the container.

Regulations on cosmetics 303

(2)

Ingredients having the potential to cause allergies and other skin problems must be displayed for the reference of consumers when they purchase the product. (3) For cosmetic products only, the amount of the contents does not have to be displayed when the product contains 10 g or 10 cc or less and there is little space for displayed items on the container or outer packaging. In addition, the method of use, amount to be used, precautions in use and handling should be indicated on the package insert or container/packaging. Further, in accordance with the Fair Competition Codes, it is also necessary to display (1) the country of origin (for imported items only) and (2) the product category (in the case of cosmetic products) in Japanese in a conspicuous place on the outside of the container or packaging. In the amount of contents description, the weight should be indicated for cosmetic products whose viscosity is 10,000 cps or above at 20°C and aerosol products, and the volume of the contents for products whose viscosity is less than 10,000 cps. Further, standards are set forth in Notification No. 546, 1959 for discrepancies between the displayed and actual contents. 16.2.3.2. Other official regulations, etc. In addition to those in the Pharmaceutical Affairs Law, attention must also be paid to the stipulations on labeling regarding cosmetics containing alcohol and other inflammable substances in the Fire Services Act (Law No. 186, 1948) and in the High-pressure Gas Control Act (Law No. 204) regarding aerosol cosmetics. The Japan Cosmetic Industry Association's own standards (Notification No. 2, 1978) for the labeling of cosmetics should also be observed. Furthermore, efforts should be made to ensure that labels prevent consumers from selecting products improperly. 16.2.3.3. Container form and materials There are no particular stipulations on the form of containers or the materials they are made from; however, the use of containers in forms which could cause cosmetics to be mistaken for drugs (e.g. injection ampules) must be avoided and the material used should help to ensure safety and be suited to the product. The container material should be tested for its chemical resistance, resistance to the contents strength and sealing qualities before use. 16.2.4. Regulations on marketing There are also standards to ensure that cosmetic products of the proper quality are marketed to the consumer in the proper manner (advertising, etc.). In order to prevent exaggerated advertising, on the basis of Article 66 in the Pharmaceutical Affairs Law (Prohibition of False or Exaggerated Advertising, etc.). Standards for Fair Advertising Practices for Drugs, Quasi-drugs, Cosmetics, Medical Devices, etc.^^ was drawn up in a Notification from the Director of the Ministry of Health and Welfare's Pharmaceutical Affairs Bureau (Notification No. 1339, 1980). These standards put limits on the kind of statements which may be made regarding indications, effects and safety in order to avoid false and exaggerated statements in product advertising.

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The following are examples of other notifications based on the spirit of basic legislation designed to protect the consumer. (1) Sale of Cosmetics together with Prizes (Notification 431, 1960) (2) The Law Against Unjustifiable Premiums and Misleading Representation (Law No. 134, 1962) (3) Restrictions on Offering Prizes in Excess of Normal Trade Custom (Fair Trading Commission Notification No. 5, July 1962) (4) Agreement of the Japan Cosmetic Industry Association and Other Organizations Concerning Self-control of the Advertising Practice to Offer Prizes and Premiums (Notification No. 117, 1965) (5) Agreement on Self-control of the Advertising for Cosmetics and Dentifrices (Notification No. 53, 1967) (6) Fair Competition Codes with Regard to Items in Labels on Cosmetics, Soaps and Dentifrices (Notifications Nos. 75 and 82, 1971; Notification No. 21, 1975) (7) Handling of Cosmetics for Consumer Preference (Notification No. 23, 1983) (8) Voluntary Standards for Packed Cosmetic Assortments (including quasi-drug products) (Notification No. 45, 1983) From the above brief description, we can appreciate just how many different regulations there are on cosmetics from manufacturing through to marketing. Further, because they represent the minimum pledge to the consumer, as was mentioned at the beginning of this chapter, each cosmetics company is carrying out research and development in earnest to ensure excellent and highly safe products. Although this chapter has concentrated on the Japanese regulations on cosmetics thus far, it is also essential to collect and analyze information with regard to FDA (Food and Drug Administration of the US) regulations and those of other countries. However, in order to provide very useful, highly safe cosmetics to consumers, efforts over and above those necessary to ensure that they comply with the various regulations must be made. In the times to come, as advances are made in cosmetics technology, we will surely see much more technically-related legislation enacted in order to ensure that the consumer is protected.

16.3. Regulations on cosmetics in other countries (Asia, Oceania, North America, South America and Europe)!^) A brief description of the various regulatory systems in force in various other countries will now be given; in Japan it is the approval system. The reader should refer to the CTFA (Cosmetic Toiletry and Fragrance Association; USA) publication on this subject for further information. 16.3J.

Asia

Taiwan (approval system). The system in Taiwan classifies cosmetics into those used on other parts other than the eyes and eyelids, those used on the eyes and eyelids, and cosmetics containing pharmaceutical agents. When formulae contain ingredients listed in

Regulations on cosmetics

305

Taiwan's Health Control Regulations or in amounts exceeding the limits in them, it is necessary to exercise caution because such products are treated as cosmetics containing pharmaceutical agents. (1) Cosmetics used on parts other than the eyes and eyelids: reporting and approval not required in accordance with regulation regarding products exempted from applications. (2) Cosmetics used on the eyes and eyelids: an application giving the product name, details of the product form, where it is used on the body, names of ingredients, etc. is submitted for approval. Specifications are required for ingredients not included in official lists. (3) Cosmetics containing pharmaceutical agents: for products coming under the categories of Suncare Cosmetics and Whitening Cosmetics, the application for approval to the Ministry of Health must contain such information as that on product specifications, test results, testing methods and test results for special ingredients (ingredients listed in Taiwan's Health Control Regulations) and details of items displayed on the product in addition to the above in order to gain approval. In cases where indications and effects are claimed for a product, usefulness data may be required as evidence. Republic of Korea (approval system). Cosmetics are classified into cosmetics and quasidrug products. (1) Cosmetics: for approval, an application containing such information as product name, names of ingredients and their quantities is made to the Ministry of Health. When new ingredients are incorporated, documentation giving their specifications and safety data for both the new ingredients and the product is also required. (2) Quasi-drug products: in the case of quasi-drug products such as mouth fresheners, deodorants, bath preparations, hair growth promoters, hair color and insect repellents, in addition to the above, documentation containing such information as product specifications and testing methods and testing methods for special ingredients must also be submitted to the Ministry of Health in order to gain approval. Thailand (approval system). Cosmetics are classified into the Cosmetics and Special Cosmetics categories. When the product contains regulated ingredients it falls into the special cosmetics category. (1) Cosmetics: documentation containing such details as product name, names of ingredients and their amounts are submitted to the Ministry of Health in order to gain approval. In the case of cosmetics containing new ingredients, their specifications and other information on them is also required. (2) Special Cosmetics: this covers such items as cosmetics containing regulated ingredients, dandruff prevention agents, permanent waving lotions, hair colors, hair growth promoters and antiperspirants. Approval is obtained by submitting specifications for the ingredients used in them and details of testing methods and test results for special ingredients to the Ministry of Health in addition to the above information. If the product claims indications and effects, usefulness data may also be required as evidence.

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science

Malaysia (approval system for some products). Cosmetics are classified into the Cosmetics and Special Cosmetics categories. (1) Cosmetics: neither reporting nor approval required at the present time. (2) Special cosmetics: covers such items as anti-dandruff agents, deodorants, whitening cosmetics, shampoos containing pharmaceutical agents and insect repellents. Approval is obtained by submitting such information as product name, product form and part of body used on, names and quantities of ingredients, ingredient specifications, product specifications, testing methods and test results, special ingredient testing methods and test results, and details of items displayed on the product to the Ministry of Health. When there are new ingredients in the formula, safety data for both the new ingredients and the product are also required. When indications and effects are claimed, usefulness data is also needed as evidence to them. Indonesia (approval system). Approval is obtained by submitting such information as product name, names and quantities of ingredients, ingredient specifications and test results, product specifications and test results, and details of items displayed on the product to the Ministry of Health. When indications and effects are claimed, usefulness data is also required as evidence. Peoples' Republic of China (approval system). Cosmetics are classified into the Cosmetics and Special cosmetics categories. (1) Cosmetics: documentation containing such details as product name, names of ingredients and their amounts are submitted to the Ministry of Health in order to gain approval. (2) Special cosmetics: This covers such items as hair growth promoters, permanent waving lotions, hair colors, whitening cosmetics and antiperspirants. Approval is obtained for them by submitting such information as product name, ingredient names and quantities, ingredient specifications, product specifications and testing methods, and product safety data to the Ministry of Health. Philippines (approval system). Approval is obtained by submitting such information as product name, ingredient names and quantities, ingredient specifications, product specifications and testing methods, and special ingredient testing methods to the Ministry of Health. When indications and effects are claimed, usefulness data is also required as evidence. Singapore. There are no regulations on cosmetics as the present time. 16.3,2,

Oceania

Australia (some products come under approval system). Although there is no obligation for reporting on general cosmetic products, for items like sunscreen cosmetics which are classified as being for therapeutic use, approval has to be obtained from the Ministry of Health by submitting an application containing such information as product name, ingredient names and quantities, product specifications, testing methods and test results.

Regulations on cosmetics 307 special ingredient quantification methods and quantification results, usefulness data and items displayed on the product. New Zealand There are no regulations on cosmetics at the present time. 16.3.3. North America USA (reporting system). The cosmetic product name and details of its ingredients are voluntarily reported to the FDA within 60 days of marketing. However, in the case of such items as sunscreens, antiperspirants and acne treatment preparations which come under the OTC category, reporting is obligatory and such information as the product name, product form and where used, ingredient names and quantities, and items displayed on the product must be submitted to the FDA. Canada (reporting system; OTC category products: approval system). For general cosmetic products, such information as the product name, product form, where used, and ingredient names are reported to the Ministry of Health within 10 days of marketing. In the case of such items as sunscreens, antiperspirants and acne treatment preparations which come under the OTC category, approval has to be obtained by submitting such information as product name, product form and where used, ingredient names and quantities, product specifications and testing methods, quantification methods for active ingredients and preservatives, and items displayed on the product to the Ministry of Health together with the OTC application documents. When the product contains ingredients not on official lists, their specifications and testing methods are also required. 16.3.4. South America Chile (approval system). Approval is obtained by submitting such information as the product name, product form and where used, ingredient names and quantities, ingredient specifications, product specifications and items displayed on the product to Ministry of Health. In the case of sunscreen products, it is also necessary to submit details of the quantification methods used for the sunscreen agents. Venezuela (approval system). Approval is obtained by submitting such information as the product name, ingredient names and quantities, ingredient specifications, product specifications and items displayed on the product to Ministry of Health. Argentina (reporting system). Such information as the product name, ingredient names and quantities are reported to the Ministry of Health. 16.3.5.

Europe

UK, Germany, Belgium, Netherlands and Luxembourg. There is no obligatory reporting for general cosmetic products. France (in-house records kept). France requires companies to keep in-house records containing such information as product name, ingredient names and quantities, ingredi-

308 New cosmetic science

ent specifications and testing methods, product specifications, testing methods and test results, product safety and usefulness. Italy (in-house records kept). Reporting is unnecessary but in-house records containing such information as product name, ingredient names and quantities must be kept. Greece (reporting system). In the case of cosmetics imported from within the EU, the product name is reported to the Greek Ministry of Health. In the case of cosmetics from outside the EU, the product name, ingredient names and quantities, product specifications and so forth, are reported to the Ministry of Health before clearing customs. Spain (reporting system). The product name, product form and where used, ingredient names and quantities, product specifications, product safety data and other such information are reported to the Ministry of Health. Portugal (reporting system). The product name, product specifications and test results are reported to the Ministry of Health within 30 days of marketing. Switzerland (reporting system; some products under approval system). For general cosmetic products, the product name, product form and where used on the body are voluntarily reported to the Ministry of Health. However, for cosmetics stating that they contain vitamins, it is necessary to apply for approval to the Ministry of Health and the Vitamin Analytical Research Institute, submitting documentation containing such details as the product name, product form and where used, the ingredients and the items displayed on the product. Austria (some products under approval system). Though there is no obligation to file reports for general cosmetic products, approval for special cosmetics containing ingredients not listed in the Government drug list, an application for approval must be made to the Ministry of Health, submitting documentation containing the product name and other details as well as usefulness data. Denmark (reporting system). The product name and names of ingredients are reported to Denmark's Environment Ministry by the date of marketing. Sweden (reporting system). The product name is reported to the Ministry of Health within 30 days of marketing. Norway (reporting system). The product name is reported to the Ministry of Health within 30 days of marketing. Finland (some products under reporting system). In the case of cosmetics for use by professional beauticians, the product name is reported to the Ministry of Health within 30 days of marketing.

Regulations on cosmetics 309

References 1. Standards and Certification Systems Concerning Drugs in Japan, 3rd. edn., Yakugyojiho Ltd., 1992. 2. Pharmaceuticals and Cosmetics Division, Pharmaceutical Affairs Bureau, Ministry of Health and Welfare, ed.: Guide to Quasi-drug and Cosmetic Regulation in Japan, Editorial supervision, Yakuji Nippo Ltd., 1992. 3. Japanese Standards of Cosmetics Ingredients, Yakuji Nippo Ltd., 1979. 4. Japanese Standards of Cosmetics Ingredients, 2nd. edn., Yakuji Nippo Ltd., 1985. 5. Supplement I to the Japanese Standards of Cosmetics Ingredients, 2nd. edn., Yakuji Nippo Ltd., 1986. 6. Supplement II to the Japanese Standards of Cosmetics Ingredients, 2nd. edn., Yakuji Nippo Ltd., 1992. 7. The Comprehensive Licensing Standards of Cosmetics by Category Part I, Yakuji Nippo Ltd., 1986. 8. The Comprehensive Licensing Standards of Cosmetics by Category Part II, Yakuji Nippo Ltd., 1987. 9. The Comprehensive Licensing Standards of Cosmetics by Category Part III, Yakuji Nippo Ltd., 1988. 10. The Comprehensive Licensing Standards of Cosmetics by Category Part IV, Yakuji Nippo Ltd., 1989. 11. The Comprehensive Licensing Standards of Cosmetics by Category Part V, Yakuji Nippo Ltd., 1990. 12. The Comprehensive Licensing Standards of Cosmetics by Category Part VI, Yakuji Nippo Ltd., 1991. 13. International Resource Manual, 3rd. edn.. Cosmetic, Toiletry and Fragrance Association, Washington, DC.

17 Cosmetics and information As mentioned in Outline of Cosmetics, cosmetics have a close connection with several scientific disciplines and areas related to them. Cosmetic products can be said to be the result of the creative use of the vast amount of information derived from them and research results. Putting this another way, much know-how and an extremely large amount of information are put to use at all stages from the planning of a cosmetic product through R&D and production right up to its marketing. In this chapter, we shall be looking at the importance of information from the R&D aspect, mention various reference books and journals related to cosmetics and touch on the increasing use of databases resulting from the widespread use of computers which are all helping us to gain a deeper understanding of cosmetics.

17.1. Importance of information in research and development Briefly speaking, as cosmetics research can move straight into the commercialization of a product right from the product planning stage through the utilization of one's accumulated know-how, it has many different levels which begin from basic research and then go on through the stages of applied research and product research to the first version of the finished products. Fig. 17.1 shows the information required at each stage for the case in which R&D proceeds from basic research, through applied research on to product research and how it is related to them. 17.1.1. Documentation

activities

By documentation activities, we mean a series of activities comprising the collection of technical information, its processing, investigation, analysis, assessment and dissemination which are carried out in an organized manner. Formerly, it was possible for researchers to cope with this individually during spare time in their research when they would collect information and process it (e.g. making card indexes for technical papers they had selected from journals). However, now that we are in the age of information, there is a limit to the amount of information that one can collect individually, there are leaks of confidential information and, for the most part, it has become very difficult to search out the necessary information from the mountains that exist. Under these circumstances, it is essential to adopt an organized approach in order to carry out research effectively. As the major factors behind this, we can give the explosive increase in the volume of information and the proliferation of its sources. As evidence of the former in the field of chemistry, every year at least 500,000 310

311

Cosmetics and information

Information collection N by individuals /' T

n o u

05 (D

en a;

1

w

^o 03 ;-( CU

X

o u

C3 OJ

W

c«

CaS04 • 2H20 + 8.2kcal

Non-woven adhe- Texture depends on nature of gel used. Being a new type of sive fabric with gel pack it is attracting attention. It is easy to use and has a very good effect when used together with other skin care cosmetics. type Non-woven fabric impregnated type

Non-woven fabric impregnated with lotions or essences. Gives a cool, comfortable feeling. Easy to use.

for the face; they are used all over the body - for example, on the neck, shoulders, arms and legs. Table 1.13 shows the variety of different pack preparations. Some of the functions of packs are as follows: (1) The skin's horny layer is maintained in a moist condition as a result of the moisture from the pack, humectant and emollient, and the moisture coming up from under the skin is kept in due to the pack's occlusive effect, hence making the skin more supple. (2) As packs have an adsorbent action and remove skin surface dirt when peeled off after drying, they are an excellent cleanser for the skin.

Skin care cosmetics 359

(3)

The drying of the film on the skin and the powder produces just the right amount of tension in the skin. After drying, the skin temperature rises and it invigorates the circulation. With the exception of the adhesive fabric type, all types of pack are applied to the skin in a suitable thickness and, after leaving for a set time, are peeled or rinsed off. As the peel-off type is very effective in removing old horny layer, it is good to use it once or twice a week. The problem with packs is that they have to be left on for a long time so they are not used very frequently in the home as people have such busy lives but they are a very important product for beauty salons because customers are very satisfied with the effect. Methods of shortening the drying time are now being developed. 1.8.2. Main ingredients of packs and masks As the materials used vary according to the type of pack, only those for the jelly and paste peel-off packs, the main types of pack in skin care cosmetics, are given in Table 1.14. 1.8.3. General manufacturing methods for packs and masks As the method for making packs and masks varies depending on the type, only those for the paste form peel-off type and the rinse-off mud type are given below. Table 1.14. Main ingredients of peel-off packs (jelly-type, paste-type) Typical ingredient

Ingredient

Amount 40-80%

Purified water

Ion exchanged water

Alcohol

Ethanol

Humectant

Polyethylene glycol (300, 400, 1500, 4000), glycerin, propylene glycol, dipropylene glycol, 1,3-butylene glycol, sorbitol and other saccharides, mucopolysaccharides, PCA-Na, etc.

2—15

Film forming agent and thickener

Polyvinyl alcohol, polyvinyl pyrrolidone, polyacetic acid vinyl emulsion, carboxymethyl cellulose, pectin, gelatin, xanthan gum

10—30

Oil component (emollient)

Olive oil, macadamia nut oil, jojoba oil, liquid paraffin, squalane, ester oils, etc.

—15

Powder

-15%

Kaolin, talc, titanium dioxide, zinc oxide, spherical cellulose, etc.

-20

Coloring agent

Permitted colorants, inorganic pigments.

q. s.

Pharmaceutical agent

Whitening agent : vitamin C and its derivatives, placentaextract Rejuvenator : pantothenyl ethyl ether, vitamins, animal and plantextracts Anti-inflammatory : Allantoin, glycyrrhizinic acid salts Germicide : Photosensitiger, TCC

q. s.

Preservative

Paraben

q. s.

Surfactant

POE oleyl alcohol ether, POE sorbitan monolaurate

Buffer

Citric acid, lactic acid, amino acids, sodium citrate, sodium lactate.

-

2% q. s.

360

New cosmetic

Water phase

Alcohol phase

science

Purified water Powder Humectant — Film agent —

Mixing —T-^ Heating — Dispersion 1 Dissolution 1 70-80°C

r Dispersion 1 [DissolutionJ

r

Mixing 1 [DissolutionJ [Deairing]

Ethanol Perfume Preservative Surfactant "

I 1

Dissolution-

[Filtering] [Cooling] [Storage] [Filling]

Fig. 1.10. Manufacturing process for paste-form peel-off pack.

The points requiring attention in the manufacture of paste form peel-off packs are the dispersion and dissolution of the film agent and the dispersion of the powders. It takes time to dissolve the film agent and it must be checked that it has dissolved uniformly and that there is none left undissolved. The powder must be well dispersed to prevent precipitates forming due to secondary coagulation (Fig. 1.10). With the exception of the heating required to dissolve the preservative and the surfactant, the manufacturing of the rinse-off mud pack is basically done at room temperature. The points requiring greatest attention are the dispersion of the clay minerals and the uniform mixing of powders into the water phase. If this is not done sufficiently well, the mud pack will not be smooth, there will be lumps in it and the water phase could separate with time (Fig. 1.11). 1.8.4. Types of pack and mask Typical formula 1. Jelly-form peel-off type 15.0 5.0

Polyvinyl alcohol Carboxymethyl cellulose

Film agent: Thickening agent:

{

Purified water -TClay mineral —^ Humectant

-*• Mixing — Dispersion room temp

• [Dissolution]-

r Mixing 1 |_DispersionJ [Deaiming]

f Ethanol . . . [Dissolution] Preservative Alcohol phase Perfume — Surfactant"

J

Powders —

[Pulverization] -

I

[Filtering] [Storage]

I

[Filling]

Fig. 1.11. Manufacturing process for rinse-off mud pack.

Skin care cosmetics 361 Humectant: Alcohol: Perfume: Preservative: Buffer: Surfactant: Purified water:

1,3-butylene glycol Ethanol

POE oleyl alcohol ether

5.0 12.0 q.s. q.s. q.s. 0.5 62.5

Manufacturing procedure After adding the buffer and humectant to the purified water, heat to 70-80° C. Add the thickening agent, film agent and mix to dissolve. After dissolving the perfume, preservative and surfactant in the alcohol, add this to the water phase and dissolve. Then deair, filter and cool. Typical formula 2. Paste-form peel-off type Film agents: Humectants: Oil component: Surfactant: Powders: Alcohol: Perfume: Preservative: Purified water:

Poly acetic acid vinyl emulsion Polyvinyl alcohol Sorbitol PEG 400 Jojoba oil Squalane POE sorbitan monostearate Titanium dioxide Talc Ethanol

% 15.0 10.0 5.0 5.0 2.0 2.0 1.0 5.0 10.0 8.0 q.s. q.s. 37.0

Manufacturing procedure To the purified water, add the powders and after they are sufficiently dispersed, add the humectants. After heating to 70-80°C, add the film agent and dissolve. To the ethanol add the perfume, preservative, surfactant and oil component. Mix this together with the water phase. De-air, filter and cool. Typical formula 3. Powder-form peel-off type When this type is dissolved in water, a calcium alginate gel is produced which forms the film. % Powders: Kaolin 30.0 Talc 20.0 Gelling agent: Sodium alginate 10.0 Gelling reactant: Calcium sulfate 35.0 35.0 Gelling regulator: Sodium carbonate 5.0 Coloring agent: q.s. Perfume: q.s.

362

New cosmetic science

Manufacturing procedure To the powders add the gelling agent, gelling reactant, gelling regulator, coloring agent and perfume in that order, mix and fill. Typical formula 4. Mud-form wash-off type After they have dried a bit, some products of this type and the cream-form wash-off type are rubbed in with the palms and then washed off (gommage type). % Humectants: Dipropylene glycol 5.0 PEG 400 8.0 Glycerin 10.0 Clay mineral: Montmorillonite 2.0 Alcohol: Ethanol 8.0 Powders: Titanium dioxide 5.0 Kaolin 10.0 Talc 5.0 Perfume: q.s. Preservative: q.s. Surfactant: q.s. Purified water: 47.0 Manufacturing procedure To the purified water add the clay mineral and the humectant ensuring sufficient wetting and dispersion. Dissolve the preservative, perfume and surfactant in the ethanol and add this to the water phase. Next, add the powders, ensuring that there is sufficient dispersion, de-air and filter. Typical formula 5. Jelly-form wipe-off or wash-off type Humectants: Thickening agents: Alkali: Surfactant: Alcohol: Perfume: Preservative: Purified water:

PEG 1500 Dipropylene glycol Sorbitol Carboxyvinyl polymer Xanthan gum Potassium hydroxide POE lauryl alcohol ether Ethanol

% 5.0 5.0 5.0 1.0 0.5 0.5 1.0 5.0 q.s. q.s. 77.0

Manufacturing procedure To the purified water add the thickening agent and mix to dissolve. Dissolve the perfume, preservative and surfactant in the ethanol and solubilize this in the water phase. Finally, dissolve the potassium hydroxide in some of the purified water and add this to the solution to neutralize it, de-air and filter.

Skin care cosmetics 363

1.9. Shaving cosmetics 1.9.1. Purposes and functions of shaving cosmetics Skin care cosmetics such as cleansing foams, lotions, milky lotions, skin creams, essences and packs are also provided for men. As men have more sebum on their skin than women, male cosmetics have a lower oil content and as they like a light feeling, many cleansing foams for the face contain a scrub agent. As well a producing a lot of sebum, many men have dry rough skin in winter. The dryness is prevented with milky lotions and essences which give a non-oily feeling when used. However, men use shaving cosmetics much more than such skin care products and as the formulations of these skin care cosmetics are similar to those for women, only shaving cosmetics, i.e. those for use before and after shaving, will be discussed here. Shaving cosmetics comprise shaving soap, shaving cream, pre-shaving lotion and after-shaving lotion. As well as making shaving easier by making the beard swell and softening it when applied before shaving, shaving soap and shaving cream prevent skin roughness due to shaving and leave a nice feeling when used. Almost all products currently on the market are the cream type. As the name suggests, pre-shaving lotion is also applied before shaving, but it is specially for electric shavers. Pre-shaving lotion helps electric shavers to slide better over the face and contain astringents and alcohol to stretch the skin in order to make the hairs stand up more rigidly, which makes shaving easier with an electric shaver. After-shaving lotion is a skin care cosmetic product applied after shaving which has a sterilizing action and gives a moist feeling to the skin. 1.9.2. Types of shaving cosmetics (1) Shaving soap. Among shaving soaps, the liquid, powder and granule types are mainly for use at barber shops and other commercial establishments. The solid type is for general use. It is necessary to prevent the powder and granule types from becoming solid through the absorption of moisture. The biggest difference between the solid type and ordinary toilet soap, which it resembles, is that lather is stressed in its formulation rather than cleansing power. So, in addition to having an oil/fat composition producing a uniform, viscous, thick, longlasting, rich lather, a lot of glycerin and other superfatting agents are often included in the formulation. (2) Shaving cream. Lathering cream and aerosol shaving cream are examples of the types of shaving cream available. Lathering cream contains 40-50% fatty acid soap. Emulsifying the soap and making the cream alkaline swells the hairs and makes them soft which lightens the task of shaving. Shaving creams are used as follows: the beard is wet with cold or warm water and then the cream is applied and worked into a lather with a wet brush. The beard is then shaved with a razor and afterwards rinsed with water. The main fatty acids used are stearic acid and coconut fatty acid. In consideration of lathering, the lasting quality of the lather and stimulating the skin, the proportions are

364 New cosmetic science

normally made 75% stearic acid and 25% coconut oil. And, in the saponification it is usual to use a mixed alkali, comprising potassium and sodium hydroxides, which maintains the cream at a suitable hardness and prevents any changes in hardness at high or low temperatures. Triethanol amine has a strong tendency to make the soap yellow so care must be taken in this respect. Further, the addition of glycerin or other humectant is very effective in preventing drying during shaving and, including petrolatum in the formula or using superfats is very effective in giving the skin a moist feeling. The total fatty acid content of a cream is 35-50% and its pH around 10. Free fatty acid and glycerin lower lathering ability but as glycerin is used as a humectant, as described above, it is necessary to carefully consider the qualities of both together when deciding on their quantities. Typical formula 1. Lathering cream Oil component:

Humectant: Alkali: Antioxidant: Perfume: Purified water:

Stearic acid Palmitic acid Coconut oil Palm oil Glycerin Potassium hydroxide Sodium hydroxide

% 25.0 5.0 10.0 5.0 10.0 7.0 1.5 q.s. q.s. 36.5

Manufacturing procedure Dissolve the potassium hydroxide and sodium hydroxide in the purified water, add the glycerin and heat to 80°C (water phase). Leaving out the perfume mix all the other ingredients together, heat to dissolve and keep at 80°C (oil phase). Gradually add the water phase to the oil phase and after adding all of it, allow the saponification reaction to fully take place. Cool to 50° C, add the perfume, mix till uniform and cool to 30°C. In addition to lathering cream, there is also the aerosol-type shaving foam, which is sold widely. This is considered to be because of the dynamic feeling of the foam and its convenience of use. Some of its other excellent features are: it softens the beard, retains moisture during shaving and it allows the razor to glide easily over the face. Owing to the recent popularity of the 2-blade razor, the foam has been made softer so that it does not clog up the blades. Aerosol shaving foams consist of a propellant and a concentrate. In order to maintain the foam for as long as possible, and make shaving easier, the concentrate is an emulsion made from soap and non-ionic surfactant. The propellant sprays the stock solution out of the container to form the foam. The softness of the foam is controlled by the type of emulsifier used. In order to prevent the destruction of the ozone layer, such alternatives to chloroflurocarbons as liquefied gaseous hydrocarbons and dimethylether are now being used for the propellant.

Skin care cosmetics 365

Typical formula 2. Shaving foam Concentrate formula Oil component: Surfactant: Humectant: Alkali: Perfume: Purified water: Filling formula Concentrate: Propellant (LPG):

Stearic acid Coconut oil fatty acid Glyceryl monostearate Glycerin Triethanol amine

% 4.5 1.5 5.0 10.0 4.0 q.s. 75.0 96.0 4.0

Manufacturing procedure To make the concentrate, add the glycerin and the triethanol amine to the purified water and heat to 70°C (water phase). Heat the other ingredients to dissolve and keep at 70°C (oil phase). Add the oil phase to the water phase and allow the reaction and emulsification to take place. Then cool to 30°C. Fill cans with the prescribed amount of the concentrate and after attaching the valve add the prescribed amount of propellant. Recently, the new-type after-foaming aerosol shaving foam has come on to the market. In this type an emulsion is formed by introducing a gas with a high boiling point (30-40° C) into a gel base at a low temperature and this is sealed in a double aerosol container. The inner container is filled with concentrate containing isopentane (boiling point 28°C) and the outer container with LPG. After the concentrate has been expelled from the aerosol container, it is heated by the skin which vaporizes the isopentane and makes the foam. The foam type is thus more convenient than the lathering cream type because there is no need to apply water and use a brush to work up a lather. Typical formula 3. After-foaming gel cream Oil component: Humectant: Surfactant: Alkali: Purified water: Foaming agent:

Palmitic acid Glycerin POE-POP block copolymer Triethanol amine Isopentane

% 10.0 15.0 5.0 6.0 59.0 5.0

Manufacturing procedure Add the alkali, and humectant to the purified water and heat to 70°C (water phase). Melt the palmitic acid at 70° C and add to the water phase. Then add the surfactant. After introducing this base solution into a container add the isopentane. Shake the container so that the isopentane forms a uniform emulsion. (3) Preshaving lotion. As the use of electric shavers has increased, the lotion-type of preshaving lotion is now widely used. It is applied before shaving to make it easier. There

366 New cosmetic science are two types. One contains zinc phenolsulfonate, tannic acid or other astringent to draw the skin together so that the hairs stand up and the other globular powders to make electric shavers slide more easily over the face. Typical formula 1. Preshaving

lotion 70

Astringent: Alcohol: Oil component:

Zinc phenolsulfonate Ethanol Isopropyl myristate Isopropyl palmitate

Perfume: Typical formula 2. Preshaving lotion containing Alcohol: Powder: Oil component: Humectant: Pharmaceutical agent: Perfume:

1.0 84.0 7.0 8.0 q.s.

powder

Ethanol Spherical powder Glyceryl tri-2-ethylhexanoate 1,3-butylene glycol Vitamin E acetate

% 94.0 4.0 1.0 1.0 q.s. q.s.

To best lubricate the passage of the electric shaver over the face, the powder should be globular in form and have a low specific gravity. (4) After-shaving lotion. After shaving lotion is a type of astringent lotion used after shaving to help heal cuts due to shaving, prevent drying of the skin and give a refreshing, cool feeling. The main types are those containing alcohol designed mainly to provide a cool, refreshing feeling and germicidal effect; those providing a cool, refreshing feeling and an anti-inflammatory effect, by cutting down on the alcohol and adding menthol and camphor; and those keeping the secretion of sebum under control through the use of powders. Each type has the ability to prevent infection in shaving cuts, draw the skin together and prevent it from drying out. Typical formula 1. High alcohol formula Alcohol: Humectant: Surfactant: Pharmaceutical agent: Plant extract: Perfume: Germicidal agent: Purified water: Ultraviolet absorbent:

type

Ethanol Dipropylene glycol POE hardened castor oil ester AUantoin Aloe extract

% 55.0 2.0 1.0 0.1 q.s. q.s. q.s. 41.9 q.s.

Manufacturing procedure Dissolve the dipropylene glycol and the allantoin in the purified water (water phase). Dissolve the other ingredients in the ethanol (alcohol phase). Solubilize the water phase in the alcohol phase and then filter.

Skin care cosmetics 361

1.10. Other cosmetics (1) Powder products. Powder, granule and capsule type products containing vitamin C or vitamin C derivatives, which are made into aqueous solutions will now be described. Such ingredients have poor stability in aqueous solution. Vitamin C and its derivatives have a reducing action and inhibit tyrosinase activity. Powder products containing them come under the category of whitening cosmetics. When using them, some powder is placed on the palm of the hand and about 10 times as much water is added to dissolve the powder. This aqueous solution is applied to the face. If the formula contains ascorbic acid dipalmitate, which is hydrophobic, an excipient and a dissolution aid may be added and the product made into granules in order to make it easier to dissolve in water. Typical formula 1. Powder type (whitening Humectants: Powder: Pharmaceutical agents:

powder)

Cane sugar PEG 6000 Silica Vitamin C Vitamin C dipalmitate

Coloring agent:

% 60.0 20.0 5.0 5.0 10.0 q.s.

Manufacturing procedure Mix the humectant, powder, pharmaceutical agents and coloring agent together and grind. Fill containers after dividing into smaller amounts. (2) Cleansing oil. This product is used as a face cleanser for removing heavy makeup. The cleanser is mixed in well with the makeup and removed. There are two types, one which is wiped off and the other is rinsed off. The latter is now the main type. The main ingredients are an oil which goes well together with the makeup, and a surfactant to aid rinsing off. With this type of product, attention should be paid to the selection and combination of the surfactants in order to ensure the formation of the O/W emulsion when rinsing off. Typical formula. Cleansing oil (for rinsing off) Oil component:

Surfactant: Perfume:

Liquid paraffin 2-ethyl hexyl stearate Silicone oil POE oleyl alcohol ether

% 50.0 20.0 20.0 10.0 q.s.

Manufacturing procedure Mix the oil component, surfactant and perfume together to dissolve. Then filter and prepare as product.

368 New cosmetic science

References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56.

Tanaka, M.: Fragrance J., 9, 13 (1994). Kitamura, K.: The 18th. IFSCC, Preprints, 1994. Ozawa, T. et al:. Skin Res., 27 (2), 276 (1985). Nilsson, G. E.: Med. Biol. Eng. Comput., 15, 209 (1977). Kligman, A. M., Takase, Y.: Cutaneous Aging, University of Tokyo Press, 1988. A. Seakall: Get Pat, 1025, 101 (1958). Wolfersberger, M. G., Tabachnick, J., Finkelstein, B. S., Levin, M.: J. Invest. Dermatol., 60, 278 (1973). Koyama, J., Horii, I., Kawasaki, K., Nakayama, Y., Morikawa, Y., Mitsui, T.: J. Soc. Cosmet. Chem., 35, 185 (1984). Ozawa, T. et al.: Fragrance J., 11 (4), 297-307 (1987). Jacobi, O. K.: Proc. Sci. Sect., TGA, 31, 22 (1959). Horii, I.: J. Br. Dermatol., 121, 587 (1989). Denda, M.: Arch. Dermatol. Res., 284, 363 (1992). Nakayama, Y. et al.: J. Soc. Cosmet. Chem. Jpn., 20 (2), 111 (1986). Middleton, J. D., Roberts, M. E.: J. Soc. Cosmet. Chem., 29, 201 (1987). Takahashi, M. et al.: J. Soc. Cosmet. Chem., 35, 171 (1984). KUgman, A.: J. Invest. Dermatol., 73, 39 (1979). Marks, R., Lawson, A., NichoUs, S.: Stratum Comeum, Springer Verlag, Heidelberg, p. 175, 1983. Takahashi, M., Machida, Y., Marks, R.: Arch. Dermatol. Res, 279, 281 (1987). Takahashi, M., Black, D., Hughes, B., Marks, R.: Chem. Exp. Dermatol., 246, 12 (1987). Grove, G. L., Kligman, A. M.: J. Geront, 38, 137 (1983). Marks, R. et al.: Br. J. Dermatol., 111, 265 (1984). Janson, L. H. et al.: Br. J. Dermatol., 107, 35 (1982). Roberts, D. et al.: J. Invest. Dermatol, 74, 13 (1980). Naito, N. et al.: Fragrance J., 16 (5), 4 2 ^ 6 (1988). Prince, L. M.: Preface, Academic Press, New York, 1977. Shinoda, S.: J. Jpn. Oil Chem. Soc. (Yukagaku), 37, 1012 (1988). Friberg, S. E.: Colloids and Surfaces, 4, 201 (1982). Lindman, B. et al.: Colloids and Surfaces, 3, 391 (1981). Gerbacid, W. E. et al.: J. Am. Oil Chem. Soc, 53, 101 (1976). Shinoda, K. et al.: J. Phys. Chem., 88, 5126 (1984). Higuchi, W. I. etal.: J. Pharm. Sci., 51, 459 (1962). Tomomasa, T.: J. Jpn. Oil Chem. Soc. 37, 1012 (1988). Shinoda, K. et al.: J. Colloids Interface Sci., 35, 624 (1971). Cockbain, E. G. et al.: J. Colloids Sci., 8, 440 (1953). Saito, H. et al.: J. Colloids Interface Sci., 24, 10 (1967). Griffin, W. C : J. Soc. Cosmet. Chem., 5, 249 (1954). Fukushima, S. et al.: J. Colloids Interface Sci., 57, 201 (1976). Barry, B. W. et al.: J. Colloids Interface Sci., 35, 689-705 (1971). Barry, B.W.et al.: J. Pharm. Pharmacol., 25, 244-253 (1973). Thomas, F. A. J. et al.: J. Pharm. Pharmacol., 20, 513-520 (1968). Thomas, F. A. J. etal.: J. Pharm. Pharmacol., 22, 417-422 (1970). Yamaguchi, M., Yoshida, K., Tanaka, M., Fukushima, S.: J. Electron Microsc, 31, 249-252 (1982). Kumano, Y. et al.: J. Soc. Cosmet. Chem., 5, 249 (1977). Mitsui, T.: J. Jpn. Oil Chem. Soc. (Yukagaku), 26 (10), 635 (1977). Powers, D. H.: Drug Cosmet. Ind., 82, 233 (1958). Czetch-Lindenwald, H. et al.: Pharm. Zentraih., 98, 362 (1959). Clor, E. J. et al.: J. Soc. Cosmet. Chem., 26, 337 (1975). Landen, K.: Am. Perform. Cosmet., 82, 77 (1967). Spir, H. W. et al.: Hautarzt, 7, 2 (1956). Zenisek, A. et al.: Biochim. Biophys. Acta., 18, 589 (1955). Yamaguchi, Y.: J. Jpn. Oil Chem. Soc. (Yukagaku), 39, 95 (1990). Ensminger, L. E. et al.: Soil Sci., 51, 125 (1948). Walker, G. F.: Clay Minerals, 7,129 (1967). Brindley, G. W. et al.: Am. Mineral, 49, 106 (1964). Plafikanov, D. et al.: Colloids Pohm. Sci., 255, 907 (1977). Park, A. C. et al.: J. Soc. Cosmet. Chem., 23, 3 (1972).

Skin care cosmetics 57. 58. 59. 60.

Takahashi, M. et al: ibid., 36, 177-187 (1985). Tojyo, K.: Pharmacia, 21, 1244 (1985). Elias, P. M.: J. Invest. Dermatol., 80, 4449 (1983). Stotts, J.: J. Invest. Dermatol, 69, 219 (1977).

369

2

Makeup cosmetics

2.1. History of makeup cosmetics Makeup cosmetics have an extremely long history. In olden times people daubed natural pigments and other substances on their faces and bodies for protective or religious purposes. And, a cosmetic palette for making up the eyes, thought to date back to around 10,000 BC, has been unearthed at an ancient Egyptian archeological site. It is considered that eye shadow, eyeliner and other items for accentuating the eyes were the main types of makeup in use at the time. In ancient Rome, it was the fashion for women to make their skin white and face powder was used for this purpose. In the Middle Ages, all classes of people used rouge and kneaded rouge was made for the cheeks and lips. In China, Japan and other parts of Asia the use of face powder and rouge was very common. During the Middle Ages, the use of makeup was criticized by certain people on moral grounds but in the 20th century it has come to be widely accepted in society. Early in the 20th century, organic colors were synthesized and used in lipsticks like those of today and manicure liquid, which was still uncommon at the time, was featured in Vogue magazine. In America in the 1940s, foundations were made to take over the role of face powder in giving the skin a beautiful and natural appearance. In the present day, makeup is made in many different fashion colors and a large variety of products, some of them varying in utility and others having functions suited to each season, are now being developed.

2.2. Types and functions of makeup cosmetics^ 9) The roles of makeup cosmetics are to make the user look more beautiful, protect their skin and have a psychological effect on them. Regarding the psychological effect, makeup cosmetics give the wearer a more definite feeling, make them more enthusiastic about doing things and feel good because putting on makeup is fun. They also give a sense of satisfaction to women who want to change their appearance^^^ The beautifying and protective functions of different types of makeup product are listed in Table 2.1.

370

Makeup cosmetics 371 Table 2.1. Functions of different makeup cosmetics Functions

Makeup item

Face powder (pressed powder)

1) 2) 3) 4)

Adjusts skin color and makes it brighter Makes the skin feel vibrant and gives a feeling of transparency Suppresses sweat and sebum so makeup lasts longer Protects skin from ultraviolet radiation

Foundation

1) 2) 3) 4)

Changes the skin color as desired Gives the skin luster, a feeling of vibrancy and transparency Covers up liver spots and freckles Protects the skin from drying and ultraviolet radiation

Lipstick

1) Applying color to the lips gives life to the face 2) Protects the lips from drying and ultraviolet radiation

Rouge

1) Applying rouge to the cheeks makes the person look cheerful and healthy 2) Improves facial form and gives relief to the face

Eyeliner

1) Making a line along the edge of the eyelashes emphasizes the contours of the eyes 2) Changing the appearance enhances the expression of the eyes

Mascara

Lengthening and curling the eyelashes emphasizes the eyes and the shading achieved gives them expression.

B 03

s

*o Eye shadow

Shading gives the eyes relief and expression to the face.

Eyebrow cosmetics

Adjusting the form of the eyebrows brings out the eyes

Nail enamel

1) Gives luster to the nails and expression to the hands and fingers 2) Strengthens the nails

Enamel remover

Removes enamel from the nails

Nail treatment

Restores nails which have become brittle and lost their luster through drying out and lipid loss to their normal condition

2.3. Types and forms of makeup cosmeticsi^-^^) Makeup cosmetics consist of many types of product in which various pigments (organic, inorganic, pearly pigments, etc.) are dispersed through a base formula. Great advances have been seen in the form and formulation of makeup cosmetics as time has gone on. There are now a great variety of different forms made for different functions, effects and convenience of use. Table 2.2 lists the main types, forms and constituents of makeup cosmetics^^^

2.4. Raw materials used in makeup cosmetics 14-24) The raw materials that are used for makeup cosmetics are such powders as coloring pigments, whitening pigments, extender pigments and pearly pigments, and the base

IY

Table 2.2. Types of makeup cosmetics and their constituents13)

Face powder and foundation

Category

.C

2 /

.-

2z $3

52

I

Oils/fats Waxes Fatty acids Higher alcohols Fatty acid esters Hydrocarbons Surfactants Metallic soaps Plasticizers High molecular con~pounds Inorganic thickeners Volatile oils (solvent) Polyhydric alcohols Inorganic powders I Purif~edwater

II

Organic coloring material Inorganic coloring material Pearly pigment

* Paper sheet-type face powder

0 0 ~ 1 0 0 0 O

(3 0 CJ 0 f j 13 5 f] 5 5

C_,

Rouge

1

1

Eyes Lipstick

Eyeliner

Mascara

Nails Nail enamel

Makeup cosmetics 373 Table 2.3. Powders used in makeup cosmetics Category

Raw materials

Extender pigment

Talc, kaolin, mica, sericite, calcium carbonate, magnesium carbonate, anhydrous silicic acid, barium sulfate, etc. (synthetic) Lithol Rubin B, Lithol Rubin BOA, Tetrabromofluorescein, etc. (natural) /^-carotene, carthamin, carmine, chlorophyll, etc.

Organic Coloring pigment

Red iron oxide, yellow iron oxide, black iron oxide, ultramarine, Prussian blue, chromium oxide, carbon black, etc.

Inorganic

Titanium oxide, zinc oxide,

Whitening pigment

Fish scale flake, bismuth oxychloride, titanium dioxide coated mica

Pearly pigment

Others

Metallic soap

Mg, Ca and Al salts of stearic acid, Zn salts of myristic acid, etc.

Synthetic polymer powder

Nylon powder, polyethylene powder, polymethyl methacrylate, etc.

Natural substances

Wool powder, cellulose powder, silk powder, starch powder, etc.

Metal powder

Aluminium powder, etc.

material that they are dispersed through. By varying the proportions of powder and base material various types of formula can be made. The base materials used include such oily substances as liquid paraffin, petrolatum, waxes, squalane and synthetic esters; humectants like glycerin and propylene glycol; and surfactants. Other raw materials include preservatives, antioxidants and perfumes. Covering and coloring ability are important functions of makeup cosmetics and their powder component is largely responsible for this. Table 2.3 shows the powders that are used in makeup cosmetics. Coloring pigments and whitening pigments are used to adjust the color shade and the covering ability. The hiding power of a powder is related to its refractive index and particle size. Table 2.4^5) shows the refractive indices for the main powders used. In makeup cosmetics, covering ability is provided by titanium dioxide and zinc oxide which have Table 2.4. Refractive indices of major powders^^^ Powder

Refractive index

Titanium dioxide (rutile) // (anatase) Zinc oxide White lead Barium sulfate Calcium carbonate Clay minerals (talc, mica, etc.) Alumina Silica

2.71 2.52 2.03 1.94-2.09 1.63'-1.64 1.51-1.65 1.56 1.50-1.56 1.55

(Kuwahara and Ando : Pigments and Colors, p. 26, Kyoritsu Zensho, 1972)

374 New cosmetic science

high refractive indices. A particle size of 0.2-0.3//m gives the maximum hiding power. The hiding power drops off both above and below this. Pearly pigments give a pearly luster to the color shade and change the quality of the feeling given. Extender pigments are used as a diluent for coloring pigments as well as to give extensibility and adhesion and absorb sweat and sebum. They also regulate the gloss of the finished makeup. Extensibility is the quality of spreading well on the skin and giving a feeling of smoothness. Talc and mica materials have this quality. These days, spherical powders having a particle size of 5-15//m are used to raise extensibility. These include spherical silica and alumina and spherical powders of such polymers as nylon, polyethylene, polystyrene and polymethylmethacrylate. This extensibility can be evaluated physically using the coefficient of kinematic friction. Table 2.526> lists the coefficients of kinematic friction for various powders. The smaller the coefficient of kinematic friction, the greater the extensibility. Adhesion is a quality indicating how well the powder will adhere to the skin. It also helps determine the feeling of the finished makeup and its lasting power. Formerly, metallic soaps were much used to enhance the adhesion but now adhesion is often achieved by applying surface treatment to the powder. Powders are also made water repellent to keep them in close contact with the skin and to prevent sweat from spoiling the makeup. Such substances as metallic soap, fatty acids, higher alcohols and silicone are used in the process to make powders water repellent. Another characteristic of powders is their absorption. This indicates their ability to absorb sweat and sebum. Their absorption gets rid of any oily luster and renders the makeup difficult to spoil. Makeup spoils more quickly for people who produce a lot of sebum and it is particularly prone to spoiling in the so-called "T zones" of the forehead and around the nose where there is a lot of sebum. Kaolin, calcium carbonate and magnesium carbonate are extremely good at absorbing sweat and sebum and making them finer enables them to absorb even more. Nowadays, porous powders are used because they are highly absorbent. Examples of porous powders are porous silica beads and porous cellulose powder which, because of their spherical nature, also enhance extensibility. Table 2.5. Coefficients of kinematic friction^^^ for powders Powder

Coefficient of kinematic friction

Talc Mica Kaolin Titanium oxide Fine particle titanium dioxide Zinc oxide Spherical silica Spherical alumina Spherical nylon Spherical polystyrene Spherical polymethyl methacrylate

0.27—0.33 0.42'-0.47 0.54-0.59 0.49 0.80 0.60 0.28—0.32 0.29 0.33 0.26-0.30 0.29

Makeup cosmetics

375

5.0 Fine particle ti tanium dioxide 4.0

3.0 42

Titanium\\ dioxide \ \

O

>

2.0

\ ' Zinc oxide Mica

rr250

1 — 350 300

400

450

Wavelength (nm)

Fig. 2.1. Capacity of powders to absorb UV radiation^^l A very important function of makeup cosmetics is to protect the skin against ultraviolet radiation. In this respect, titanium dioxide and zinc oxide have great covering capacity so they provide good protection against ultraviolet radiation but with consideration for how the finished makeup will look, not much should be used. Although makeup using a foundation may look good indoors, whiteness may show through when outside in strong sunlight. To prevent this from happening, foundations containing photochromic powders, whose color changes reversibly according to the amount of light, are being developed. However, fine particle titanium dioxide, which has an average particle size of around 0.03 jum, is not only an excellent ultraviolet screen but also transmits visible light well because of its fine particle size, as shown in Fig. 2.P^\ so the color applied will not appear whitish and the finished makeup will look natural. In addition to fine particle titanium dioxide, zinc oxide and zirconia are also used in makeup cosmetics to provide protection against ultraviolet radiation. Other raw materials will be discussed with reference to the individual products in which they are used.

2.5. Face powder and pressed powder Face powder is a type of cosmetic that has been in use since long ago for the purpose of changing the color of the face to make it more attractive and cover up liver spots, freckles and other such blemishes. However, since the advent of foundations, their main purpose has been to remove oily luster due to sweat and sebum and keep the makeup looking good for longer. Through the addition of pink or blue color, they are now also used to make a subtle change to the skin color, or, for the same effect as rouge on the cheeks.

376 New cosmetic science

In addition, there are multi-color molded powder products comprising two or more colors in a medium compact which produce a very novel effect in the makeup. There are different forms in which face powders are available. There is loose powder, in which powder is the main component; compact powder, a solid form in which a small amount of oil has been added as a binding agent; paper powder, in which the powder has been applied to paper; liquid face powder, in which powders are dispersed through an aqueous solution; and kneaded powder, which has glycerin or some other solution kneaded into it. Currently, loose powder and compact powder are the main types used. Liquid face powder and kneaded face powder were used much in the past but now they are used largely for stage and other types of special makeup. 2.5.7. Loose powder Loose powder is a powder-form product in which almost all the raw materials are powders and no oil is used. Loose powder is mainly applied on top of emulsion and oil-based foundations to achieve a matt, clear skin color by reducing oily luster and stickiness and keep the makeup looking good for longer by keeping sweat and sebum under control. As loose powder is applied using a puff, it must spread smoothly. With this in mind, the main powder used is generally talc. Kaolin and titanium oxide are used to give a matt finish and covering capacity, zinc stearate and zinc myristate for good adhesion, and calcium carbonate and magnesium carbonate to absorb sweat and sebum. Coloring pigments and pearly pigments are used to enhance the skin color. Typical formula. Loose powder Talc Kaolin Titanium dioxide Zinc myristate Magnesium carbonate Sericite Coloring pigment Perfume

% 75.0 5.0 3.0 5.0 5.0 7.0 q.s. q.s.

Manufacturing procedure Mix the talc and coloring pigment in a blender. Then add the remaining materials, mix well together and adjust the color shade. Spray in the perfume and mix in well. After grinding in a grinder, pass through a sieve. 2.5.2. Compact powder Compact powder has virtually the same function as loose powder. Loose powder is generally for use in the home while compact powder is used when away from home to touch up the makeup. The materials used to make compact powder are basically the same as those for loose powder but around 5% oil is added as a binding agent to make it into the compact form.

Makeup cosmetics IHl Typical formula. Compact powder Powders:

Talc Sericite Kaolin Titanium dioxide Zinc myristate Magnesium carbonate Coloring pigment Squalane Glyceryl tri-iso-octanoate Preservative, antioxidant Perfume

Binding agent: Other materials:

% 55.0 15.0 10.0 5.0 5.0 5.0 q.s. 3.0 2.0 q.s. q.s.

Manufacturing procedure Mix the talc and coloring pigment in a blender. Add the remaining powders, mix well together, add the binding agent and antioxidant and adjust the color shade. Spray in the perfume and mix in well. After grinding in a grinder, pass through a sieve and compress into the container. 2.5.3. Paper sheet-type face powder Paper sheet-type face powder is made by applying loose powder to paper to make it handy to carry around. It absorbs the sweat and sebum which appear on the skin and makes it easy to touch up the makeup. The raw materials used are virtually the same as those for loose powder but a watersoluble polymer is added to fix the powder on the paper. Powders are dispersed through a solution of a water-soluble polymer and this is applied evenly to the paper with a coater. The paper is then dried and cut to a suitable size for putting into a case. 2.5 A, Liquid face powder Liquid face powder is a light cosmetic which gives a cool and refreshing feeling. It is made by dispersing loose powder through a lotion containing glycerin, etc.. When used, it is shaken well to make it into a uniform mixture. It is best to use powders which settle uniformly and do not form suspensions or settle out. They should also not adhere to the sides of the bottle. The features of liquid face powder are its cool and refreshing feeling and its thinness as a makeup. 2.5.5. Other powder

cosmetics

(1) Baby powder Baby powder is used for infants. As it should be very smooth, absorb moisture and protect the skin, the main ingredient is talc. It also contains a germicidal agent to prevent diaper rash and the like. Being for infants it is important to select germicidal agents and perfumes which do not produce irritation. Baby powder comes in two forms. One is a loose powder in which powders are the

378 New cosmetic science

main raw materials and the other is a compact powder which contains around 5% oil as a binding agent. A typical baby powder formula is given below. Typical formula. Baby powder (loose powder type) Powders: Other materials:

Talc Zinc oxide Magnesium stearate Germicidal agent Perfume

%

93.0 3.0 4.0 q.s. q.s.

Manufacturing procedure Same as for loose powder. (2) Talcum powder Talcum powder is a cosmetic for use on the whole body and produces a very smooth feeling. As it absorbs sweat and moisture it is very good when used after a bath in summer or after shaving. It contains more talc than ordinary loose powders and metallic soap to improve adhesion. Germicidal agents and other substances are also added to achieve various purposes. Typical formula. Talcum powder Powders: Other materials:

Talc Magnesium stearate Germicidal agent Perfume

% 95.0 5.0 q.s. q.s.

Manufacturing procedure Same as for loose powder.

2.6. Foundations In the past, face powder was the main type of base makeup. But with the appearance of emulsion-form, cake-form, stick-form and other types of foundation as makeup cosmetics in the 1940s, the main functions of face powder became keeping the makeup looking good and touching it up. As foundations now have other functions, such as enhancing skin color, adjusting skin quality, covering liver spots and freckles, protecting the skin from ultraviolet radiation and other external stimuli, and treating skin conditions, they are currently considered separately from face powders. Although there are many different types of foundations they can be broadly divided into powder compact form, oil-based foundations and emulsion foundations (O/W or W/0 emulsion). Table 2.6 shows a classification of foundations by type along with their main features. In Europe and the United States, liquid cream foundations are the main type but, in Japan, the powder compact foundation are more common. In order to prevent the makeup from spoiling, powders which have been made hydro-

Makeup cosmetics 379 Table 2.6. Classification of foundations by type Constituents (%) xjpc

Characteristics

Powder

Oil

Powdery type

80-^93

7—20

Pharmaceutical agent

Enhances skin color, handy to carry around

Dual-use type

80-^93

7-20

Pharmaceutical agent

As above, can be used with or without water

Cake type

80—85

2-20

Emulsifier

For use with water. Gives a cool, refreshing feeling

Oily type

35'-60

40-65

Pharmaceutical agent

Good adhesion, water resistant

W / 0 emulsion type 1 5 - 5 5

30-70

5-30

Emulsifier, humectant

M a k e u p d o e s n ' t spoil, handy to carry around

0 / W emulsion type 10—25

15—30

40—70

Emulsifier, humectant

Spreads easily, good for treating skin conditions

W / 0 emulsion type 1 0 - 3 5

15—50

20-60

Emulsifier, humectant

Makeup doesn't spoil

0 / W emulsion type

10—25 50—80

Emulsifier, humectant

Spreads easily, good for treating skin conditions, moist feeling

15—50

Emulsifier, humectant

Makeup doesn't refreshing feeling

Compact type

Water

Creamy type

5—20

Liquid type W / 0 dispersed type 10-30

30—50

Others

spoil,

phobic through silicone treatment are included or a refreshing feeling is obtained through the use of a compact foundation with a wet sponge. Sunscreen foundations are now becoming very popular to protect the skin from ultraviolet radiation in summer. On the other hand, in winter when it is dry and cold, emulsion foundations which moisturize the skin are used. There is also a W/0 type emulsion foundation which contains wax. This is a solid-type emulsion foundation which is molded into a compact. For a foundation to be used in point makeup to cover liver spots, freckles and other blemishes, the oil-based type is most suitable as it has greater covering ability. 2.6.1. Powdery

foundations

A major type of powder compact foundation is the powdery foundation. After applying a foundation cream, powdery foundation is applied to the skin by putting a suitable amount on a sponge. As this makes it so easy to touch up the makeup when one is away from home, powdery foundation is widely used in Japan by people of all ages. Powdery foundation is composed of extender pigments, whitening pigments, coloring pigments, binding agents, perfumes, etc.. Extender pigments such as talc, mica and sericite are used to make them spread well and feel smooth to the touch. With consideration for making the finished makeup look beautiful and enhancing the skin color, powdery foundations contain more coloring pigments and whitening pigments than compact powder. Although the main types of coloring pigment used are iron

380 New cosmetic science

oxide inorganic pigments, high chroma organic pigments are also sometimes employed to make the skin color prettier and titanium dioxide coated mica (pearly pigments) to impart a suitable luster to the finished makeup. The oil used as a binding agent may be a natural animal or plant oil, a mineral oil such as liquid paraffin or a synthetic ester oil. Silicone oil is used to reduce the spread of the foundation and make it water repellent. To improve moldability, such semi-solid oils as lanolin or hydrocarbon waxes may be added. The amount of binding agent is determined with a view towards making the foundation as easy to use as possible for its designed purpose but the oil absorption characteristics of the powders used in it are also considered. The oil absorption characteristics indicate the ability to absorb oil. This is found by adding oil gradually to 100 g of powder and kneading it in. The amount of oil in ml which has been added at the point at which the mixture becomes a lump is the oil absorption of the powder. Oil absorption is a parameter indicating the physical properties of a powder. Typical formula. Powdery foundation Powders:

Binding agents:

Other materials:

Talc Mica Kaolin Titanium dioxide Titanium dioxide coated mica Zinc stearate Red iron oxide Yellow iron oxide Black iron oxide Nylon powder Squalane Lanolin acetate Octyldodecyl myristate Neopentylglycol octanoate Sorbitan mono-oleate Preservative, antioxidant Perfume

% 20.3 35.0 5.0 10.0 3.0 1.0 1.0 3.0 0.2 10.0 6.0 1.0 2.0 2.0 0.5 q.s. q.s.

Manufacturing procedure Same as for compact powder. 2.6.2. Dual-use foundations^^^ Dual use foundations are foundations which can be used either on a dry or a wet sponge and they are the main type of summer foundation. Their special features are their convenience, their cool, refreshing feeling and their ability to keep makeup looking good when used with a wet sponge. When powdery foundations are used with a wet sponge, the powders in them, being hydrophilic, absorb water causing them to cake which makes them difficult to use. In

Makeup cosmetics 381 dual-use foundations, this caking has been prevented by subjecting the powders to a process which makes them hydrophobic. The basic ingredients of dual-use foundations are silicone treated powders and binding agents. However, as they are mainly used in summer, they often contain ultra-fine titanium dioxide and ultraviolet absorbents to provide protection against ultraviolet radiation. Typical formula. Dual use foundation Powders:

SiHcone-treated talc SiHcone-treated mica SiHcone-treated titanium dioxide SiHcone-treated ultra-fine titanium dioxide SiHcone-treated red iron oxide SiHcone-treated yellow iron oxide SiHcone-treated black iron oxide Zinc stearate Nylon powder Squalane Solid paraffin Dimethyl polysiloxane Glyceryl tri-iso-octanoate Octylmetoxy cinnamate Preservative, antioxidant Perfume

Binding agents:

UV absorbents: Other materials:

% 19.2 40.0 15.0 5.0 1.0 3.0 0.2 0.1 2.0 4.0 0.5 4.0 5.0 1.0 q.s. q.s.

Manufacturing procedure Same as for compact powder. 2.6.3.

Cake-type

foundations

Cake-type foundations are a compact foundation used with a wet sponge. They are much used in summer because of the cool, refreshing feeling they give. This type of foundation contains a hydrophilic surfactant so that it becomes creamy when put on a wet sponge. The creaminess is due to the emulsion that is formed when it is mixed with water. This was the main type of foundation product for summer use before the advent of the dual-use type which has now taken over as the main type because of its convenience. However, it is still much used because, being used with water it refreshes and is good for people who like thin makeup. Typical formula. Cake-type Powders:

foundation Talc Kaolin Sericite Zinc oxide Titanium dioxide

% 43.1 15.0 10.0 7.0 3.8

382 New cosmetic science Red iron oxide Yellow iron oxide Black iron oxide Squalane POE sorbitan mono-oleate Isocetyl octanoate Isostearic acid Preservative, antioxidant Perfume

Binding agents:

Other materials:

1.0 2.9 0.2 8.0 3.0 2.0 4.0 q.s. q.s.

Manufacturing procedure Same as for compact powder. 2,6 A,

Oil-based

foundations

In this type of foundation, powders are dispersed through a base material consisting of oils. There is a compact and a stick form. They are suitable for autumn and winter because of their strong emollient effect. Among the features of oil-based foundations, they spread well on the skin, adhere well and makeup using them does not spoil easily. As this type of foundation has great covering ability, it is used cover up pronounced liver spots, freckles and birthmarks which ordinary foundations would not be able to hide. To prevent the sticky feeling which an oil-base tends to give, the formula must be designed in consideration of the individual characteristics of the oils and powders used. The following formulae are for a compact-type oily foundation and one with great covering ability. Typical formula 1. Oil-based foundation (compact type) Powders:

Binding agents:

Other materials:

Talc Kaolin Titanium dioxide Red iron oxide Yellow iron oxide Black iron oxide Solid paraffin Microcrystalline wax Beeswax Petrolatum Lanolin acetate Squalane Isopropyl palmitate Antioxidant Perfume

17.8 15.0 15.0 1.0 3.0 0.2 3.0 6.0 2.0 12.0 1.0 6.0 18.0 q.s. q.s.

Manufacturing procedure Make a solution of the binding agents and antioxidant at 85°C. Mix the powders together and after adequate mixing and grinding, add this to the solution while agitating. Using a

Makeup cosmetics 383

colloid mill, break up the powders and disperse them through the solution. Add the perfume, de-air, fill containers at 70° C and cool. Typical formula 2. Foundation for hiding blemishes (stick-type) Powders:

Talc Kaolin Mica Titanium dioxide Red iron oxide Yellow iron oxide Black iron oxide Solid paraffin Microcrystalline wax Petrolatum Dimethyl polysiloxane Squalane Isopropyl palmitate Antioxidant Perfume

Binding agents:

Other materials:

% 2.8 20.0 3.0 20.0 1.0 3.0 0.2 3.0 7.0 15.0 3.0 5.0 17.0 q.s. q.s.

Manufacturing procedure Same as for compact-type. 2.6.5, 0/W emulsion

foundations

An O/W emulsion foundation is a system in which the oil phase and the powders are dispersed through the water phase to form an emulsion. There is a cream type and a liquid type. As they give a moist feeling when used and are good for treating skin problems, they are the favorite type of foundation in Europe and America where the climate is dryer and the humidity is lower than in Japan. However, it is difficult to keep makeup looking good with them because they are easily affected by sweat and sebum. For an O/W type emulsion, the powders (pigments) must be uniformly dispersed through the water phase and a stable emulsion system must be maintained. Though moistness increases as the viscosity decreases, the most important thing to find out is how much the external phase viscosity can be reduced before the system becomes unstable. So, when designing formulae, it is necessary to carefully consider such points as the selection of the powders, the composition of the oil phase, selection of the emulsifier and emulsification and dispersion methods. The following formula is for the liquid type. This can be changed to the cream type by raising the proportion of the oil phase (internal phase) and increasing the quantity of powder. Typical formula. O/W emulsion foundation (liquid type)^^^ Powders:

Talc Titanium dioxide Red iron oxide

% 3.0 5.0 0.5

384 New cosmetic science

Water phase:

Oil phase:

Other materials:

Yellow iron oxide Black iron oxide Bentonite POE sorbitan monostearate Triethanolamine Propylene glycol Purified water Stearic acid Isohexadecyl alcohol Glyceryl monostearate Liquid lanolin Liquid paraffin Perfume, Preservative

1.4 0.1 0.5 0.9 1.0 10.0 56.4 2.2 7.0 2.0 2.0 8.0 q.s.

Manufacturing procedure Disperse the hydrophilic system thickening agent, bentonite, through the propylene glycol and add the purified water. After mixing this in a Homomixer at 70° C, add the rest of the water phase ingredients and mix adequately. To this mixture add the powders after adequate mixing; grind while stirring and then process in a Homomixer at 70°C. Next, make a solution of the oil phase ingredients heating to 70-80°C and add this gradually. Process in the Homomixer at 70°C. While stirring, cool to 45°C. Add the perfume and cool to room temperature. Finally, de-air and put in containers. 2.6,6, W/0 emulsion

foundations

The W / 0 emulsion foundation has been with us since long ago. The only drawback is that it feels sticky on use because the external phase is oil. However, the advent of silicone surfactants has enabled W / 0 emulsions with silicone oil as their external phase to be developed, which are highly stable. Foundations using this new type of W/O emulsion produce a more refreshing feeling and the makeup stays looking good, which is not usual with this type of foundation. Among this type, there is a 2-layer dispersed foundation (shake well-type). This foundation has a low viscosity and becomes a W / 0 emulsion when shaken. As it has a cool, refreshing and moist feeling, it is very popular in summer. Recently, a solid form of W / 0 emulsion foundation has been developed. This type of foundation is very popular as in addition to making beautiful makeup and being good for treating skin problems, it has the convenience of being in compact form. This is basically the cream type which has been made solid by the addition of wax and put in a container. Typical formulae for the W / 0 cream type and the 2-layer dispersed type are given below. Typical formula 1. W/O emulsion foundation (cream type)^^^ Powders:

Sericite Kaolin Titanium dioxide Red iron oxide

% 5.36 4.0 9.32 0.36

Makeup cosmetics 385 Yellow iron oxide Black iron oxide Liquid paraffin Decamethyl cyclopentasiloxane Polyoxyethylene denatured dimethyl siloxane Purified water Dispersing agent 1,3-butylene glycol Preservative Stabilizer Perfume

Oil phase: Water phase:

Other materials:

0.8 0.16 5.0 12.0 4.0 51.9 0.1 5.0 q.s. 2.0 q.s.

Manufacturing procedure After mixing the water phase ingredients together at 70° C, mix and grind the powders and add this to the water phase. Then process at 70°C in a Homomixer. Add the stabilizer, which has been dissolved in some of the purified water, and stir. Add the oil phase, which has also been heated to 70° C, and process in the Homomixer. While stirring, cool to 45°C and add the perfume. Cool to room temperature. Finally, de-air and put into containers. Typical formula 2, W/0 emulsion foundation (2-layer dispersed typep^^ Talc Titanium dioxide Silicic acid anhydride Nylon powder Coloring pigment Octamethyl cyclotetrasiloxane Pentaerythritol rosinate Neopentyl glycol di-iso-octanoate Squalane Glyceryl tri-iso-octanoate Poly oxy ethylene denatured dimethyl poly siloxane Purified water 1,3-butylene glycol ethanol

Powders:

Oil phase:

Water phase:

7.0 12.0 2.0 4.0 2.0 10.0 1.5 5.0 2.5 2.0 1.5 39.5 4.0 7.0

Manufacturing procedure Mix the water phase ingredients together and add the powders after mixing and pulverizing. Mix with a Homomixer. Make a solution of the oil phase ingredients; add this and mix with the Homomixer. Finally, de-air and put into containers.

2.7. Lipsticks and rouge31-37) 2.7.7. History

of lipstick^^-^^

At the time of the Greek and Roman empires, colors taken from certain plants were applied to the lips and cheeks. Following that, carmine (cochineal) taken from the cochi-

386 New cosmetic science

neal bug {Coccus cati L.) came into general use in western Europe and carthamin taken from safflowers in Japan. The modern stick-form lipstick composed of oils, fats and waxes did not appear until after the World War I. Carmine and carthamin continued to be used as the colors for lipstick but the synthetic color tetrabromofluorescein has now come into use recently enabling long-lasting lipsticks to be made. Since around 1940, synthetic colors have taken over from carmine and lipstick colors which can be matched to women's hairstyles and clothes are now very common. Recently, lipsticks have seen many innovations such as the use of powders with a pearly luster to produce a great range of tones and qualities and the making of emulsion types by including water and humectants in the base formula. 2.7.2, Quality requirements for lipsticks From the point of view of quality, lipsticks should satisfy the following conditions: (1) they should not cause irritation or harm to the lips (2) they should not have unpleasant taste or odor (3) they should go on smoothly, not smear and stay looking good for the required amount of time (4) they should retain their form with no breakage, deformation or softening during storage or use (5) they should neither sweat nor bloom (6) they should maintain their attractive appearance and there should be no change in the color 2.7.3. Raw materials of lipsticks Lipsticks consist mainly of an oily base material and coloring agents. In order to satisfy the above quality requirements, it is necessary to combine the raw materials effectively. (1) Oily base material Waxes which are solid at ordinary temperatures are used to provide the stick form of lipsticks. The waxes used are natural waxes such as carnauba wax, beeswax, candelilla wax and Japan wax, and mineral waxes such as solid paraffin, microcrystalline wax, ceresin and other hydrocarbon waxes. Oils used are those that are liquid at ordinary temperatures or whose melting points are around body temperature. Examples are such natural oils as cocoa butter, castor oil, jojoba oil, macadamia nut oil and lanolin oil; such hydrocarbon oils as petrolatum and liquid paraffin and synthetic fatty acid esters. Among them, castor oil, which has been in use for a very long time, gives the molded lipstick a proper viscosity. It is also important because it acts as the solvent for the staining dyes. In general, the natural ingredients used have a certain amount of polarity so they help to ensure the stability of the pigment dispersion. Among the often used oils, the natural waxes have particularly great hardening capacity. Because of such excellent characteristics, natural ingredients are used a lot in lipsticks but it is necessary to pay attention to sweating of the lipstick, due to the absorption of moisture by the raw materials, as well as rancidity'^^^ Recently a variety of new synthetic oils have been developed and are

Makeup cosmetics 387

widely used because they do not have the unpleasant oily smell of fats and oils derived from plant and animal sources and they are of uniform quality. Glycerides are an example of synthetic oils used in lipsticks, particularly triglycerides of which there are many. Special types of glyceride can be designed by varying the carbon numbers and the branch positions of the aliphatic acids. Ester oils other than glycerides, e.g. liquid waxes, are also widely used. Materials like octyldodecyl ricinoleate synthesized by imitating the structure of natural substances and polybutene, which have no polarity, are also utilized. In some cases, a small amount of a lipophilic non-ionic surfactant or other substance is added to ease the dispersion of colors through the lipstick base. Lipsticks are mainly composed of oily ingredients like the ones described above and recently, various kinds having a humectant function, have started to be used in consideration of the lips' moisture balance. In some lipsticks, an emulsion which directly incorporates water and a humectant in stable proportions is used in the base formula'^^^^^ In some others, ultraviolet absorbers and reflectors, and other pharmaceutical agents are added to protect the lips against ultraviolet radiation and from drying out. There are also lip creams in which no coloring agent is included in the lipstick base. (2) Coloring agents There are almost as many sets of cosmetic color regulations as there are countries in the world. The colors for lipsticks must therefore be selected from among those approved in the countries where they are to be sold. The synthetic organic colors are divided into dyes and pigments on the basis of their structures and properties. Pigments comprise color pigments and lake pigments which are made by converting dyes into insoluble form by combination with metallic compounds. Pigments determine the color of lipsticks. To improve the lasting power of the color on the lips, staining dyes are used as well. Examples of these dyes are tetrabromofluorescein, tetrachlorotetrabromofluorescein and dibromofluorescein. Castor oil is normally used for the dissolution of dyes but as the solubility is low, solvent oils may be used as well. They are butyl stearate, diethyl sebacate, tetrahydrofurfuryl alcohol and their acetate. To obtain different shades, a variety of inorganic pigments are used in addition to the synthetic organic colors. Titanium dioxide, red iron oxide, yellow iron oxide and black iron oxide are used to adjust the tone and brightness, and such pearly pigments as titanium dioxide coated mica and colored titanium dioxide coated mica to give a pearly luster. Other inorganic pigments are also used to give the lipstick good skin adhesion and the right quality. These days, the surfaces of inorganic pigments are treated using various methods in order to enhance their dispersion and stability. Typical formula 1. Oil-based lipstick % Titanium dioxide Lithol Rubin B Lithol Rubin BCA Tetrabromofluorescein Candelilla wax SoHd paraffin

5.0 0.6 1.0 0.2 9.0 8.0

388 New cosmetic science Beeswax Carnaubawax Lanolin oil Castor oil Cetyl octanoate Isopropyl myristate Antioxidant Perfume Manufacturing

5.0 5.0 11.0 25.2 20.0 10.0 q.s. q.s.

procedure

Add the titanium dioxide, Lithol Rubin B and Lithol Rubin BCA to part of the castor oil and grind in a roller mill (pigment component). Dissolve the tetrabromofluorescein in another part of the castor oil (dye component). Melt the other ingredients by heating and mix them together; then add the pigment and dye components, and stir in a Homomixer to obtain uniform dispersion. Pour into molds and cool immediately to make stick-form lipstick. Typical formula 2. Emulsion type lipstick^^"^ Titanium dioxide Lithol Rubin B Lithol Rubin BCA Tetrabromofluorescein Seresin Candelilla wax Carnauba wax Castor oil Glyceryl di-isostearate Polyoxyethylene(25)polyoxypropylene(20)2-tetradecyl ether Purified water Glycerin Propylene glycol Ultraviolet absorbent Antioxidant Perfume

% 4.5 0.5 2.0 0.05 4.0 8.0 2.0 30.0 39.95 1.0 5.0 2.0 1.0 q.s. q.s. q.s.

Manufacturing procedure Add the titanium dioxide, Lithol Rubin B and Lithol Rubin BCA to part of the castor oil and grind in a roller mill (pigment component). Dissolve the tetrabromofluorescein in the castor oil (dye component). Make a uniform solution at 80°C from the purified water, glycerin and propylene glycol (water phase). Melt the other ingredients by heating and mix; then add the pigment and dye components, and stir in a Homomixer to obtain uniform dispersion. Add the water phase and make into an emulsion in the Homomixer; then pour into molds and cool immediately to make stick-form lipstick.

2.8. Rouges (rouge, cheek color and blush-on products) Rouges are applied to cheeks to tint the face a shade of red and give a healthy complex-

Makeup cosmetics 389

ion. For this purpose, the main pigments used have been red ones but in the past few years, the range of colors has been expanded to include browns and blues. The forms of rouges are compact, liquid, cream and stick. The one in general use is the compact. The base formula is virtually the same as that for compact face powders and foundations. Normally, a definite color is not desired, rouges have less covering ability than foundations and the amount of coloring pigment in them is 1-6%. Dyes are not used because they will stain the skin. The quality requirements for rouges are as follows: (1) they should fit in well with foundations and it should be easy to smooth off the brush marks (2) there should be no change in color (3) they should have a suitable coverage, luster and adhesion (4) they should be easy to wipe off and should not stain the skin Typical formula 1. Compact rouge Talc Kaolin Zinc myristate Pigment Liquid paraffin Perfume Preservative

% 80.0 9.0 5.0 3.0 3.0 q.s. q.s.

Manufacturing procedure Mix the ingredients, except the perfume and the binder (liquid paraffin), together well, in a blender. Spray the binder and the perfume into the blender and then pulverize. Sieve and press. Typical formula 2. Oil-based kneaded rouge Kaolin Titanium dioxide Red iron oxide Lithol Rubin BCA Ceresin Petrolatum Liquid paraffin Isopropyl myristate Antioxidant Perfume

% 20.0 4.2 0.3 0.5 15.0 20.0 25.0 15.0 q.s. q.s.

Manufacturing procedure Add the kaolin, titanium dioxide, iron oxide and Lithol Rubin BCA to some of the liquid paraffin and grind in a roller mill (pigment component). Heat the other ingredients and stir them into a solution; then add the pigment component and obtain a uniform dispersion with a Homomixer. While stirring, cool to 50°C and put into containers.

390 New cosmetic science

2.9. Eye makeup^^) 2.9.L History and types Eye makeup has a very long history and eye shadow and eyeliner have been in use since the time of the ancient Egyptians. In Japan, eyebrows had been blackened for a long time but it is only comparatively recently that eye makeup has come into general use. The wide use of eye makeup spanning all age groups has come about as the result of changes in lifestyle and a heightened interest in fashion. There is a tremendous variety of eye makeup products. The application of eye makeup products makes the eyes more pronounced and gives them expression. If all combinations of base materials and different forms of eye makeup are taken into account there is a very large number of products. This section will also touch on removers and other special products which are essential to eye makeup. Eye makeup products comprise the following: (1) Eye makeup: eyeliner, mascara, eye shadow, eyebrow cosmetics. (2) Other special products: eye makeup remover, eye wrinkle care products, false eyelashes and adhesives. 2.9,2. Points for attention with eye makeup products As for other cosmetic products, it is very important to pay sufficient attention to safety. With regard to strictness of safety requirements, they can be ranked in order of their proximity to the mucous membrane of the eye as follows: eyeliner > mascara, eye shadow > eyebrow cosmetics When making formulae for them, attention must be paid to the following points: (1) Pigments. In Japan, because of the color of the eyes, eyelashes and hair, the colors normally used for eyeliner, mascara and eyebrow cosmetics are blacks, grays and browns but in the case of eye shadow, bright pinks, purples, blues, greens and colors with a pearly luster are also used. In Europe and the United States, there is a much wider range of colors due to the tremendous variety of eye, eyelash, hair and skin colors. The major pigments used for eye makeup are inorganic pigments like black, red and yellow iron oxides; ultramarine and carbon black and extenders like talc and kaolin and pearly pigments like titanium dioxide coated mica. The colors used in cosmetics sold in a particular country must be approved in that country and it is necessary to keep in mind that the regulations regarding colors are different in each country. (2) Measures against microbial contamination. Measures should be taken against microbial contamination, as there is the chance that eye makeup may go into the eyes. In order to do this, it is necessary to consider hygiene control at all times, from the raw materials stage, through the production stage, to the time that they come on to the user's hands to be applied to the eyes. With water based eyeliners and mascaras which contain natural

Makeup cosmetics 391 and synthetic film formers and thickeners, special care should be taken if they are the type in which the brush is kept in the case because it is so easy for microbes to multiply in these conditions. (1) Raw materials stage: sterilization to prevent microbial contamination of the powders and other raw materials (especially in the case of natural materials). (2) Production environment and processes: arrange environment and processes so that contamination is prevented during production. (3) Containers and other packaging materials: sterilization. (4) Microbial resistance of product: measures against secondary contamination at time of use (base formula, include preservative in formula). Although the above apply to all cosmetics, the regulations in every country concerning microbial contamination are particularly strict in the case of eye makeup cosmetics. 2.9.3.

Eyeliner

Eyeliner is applied along the upper and lower hairlines of the eyelashes with a fine brush to emphasize the impression given by the eyes and make them more attractive. The following types of eyeliner are available on the market: f Film type (Water-based ] I Liquid form \ [ Non-film type Oil-based Solid form

Powder compact type Pencil type

Although there are many types of liquid-form eyeliner, in all types pigments are dispersed through a low viscosity liquid in such a way that no settling of pigments occurs. They come in glass bottles, metal or plastic tubes with an attached brush. The quality requirements for eyeliners are as follows: (1) There must be absolutely no irritations as they are applied at the edge of the eyes. (2) They must dry quickly (particularly in the case of people with double folded-in eyelids for whom it would be unpleasant if drying were slow as the eyes must be closed until the eyeliner has dried). (3) They should be easy to apply. (4) The film should have flexibility. (5) The finished eye makeup should look attractive. (6) The makeup should last well; it should not peel off, smudge or crack. (7) It should be waterproof and not be spoiled or come off with sweat or tears. (Special waterproof and water-resistant types especially for use when in the water should not come off when swimming). (8) There should be no precipitation or separation of pigment. (9) There should be no microbial contamination. The main constituent of the film type, which is much used in Japan, is a polymer emulsion. After application, when the water in the formula vaporizes, a continuous film with a luster forms on the skin. As the film is insoluble in water, the eyeliner does not

392 New cosmetic science run with sweat or tears and it can be removed as one piece by wetting with remover. This type is called a "peel-off-type". Typical formula 1. Film-type eyeliner Black iron oxide Polyvinyl acetate emulsion Glycerin Polyoxyethylene sorbitan mono-oleate Carboxymethyl cellulose (10% aqueous solution) Acetyltributyl citrate Purified water Preservative Perfume

% 14.0 45.0 5.0 1.0 15.0 1.0 19.0 q.s. q.s.

Manufacturing procedure Add the glycerin and polyoxyethylenesorbitan mono-oleate to the purified water and heat to dissolve the ingredients. Then add the black iron oxide and grind in a colloid mill (pigment component). Heat the other ingredients together to 70°C, stirring. Add the pigment component to this and disperse evenly using a Homomixer. In the formulation of this type, the most important thing is the selection of the polymer emulsion. So, it should be chosen with consideration for the eyeliner's usability and should thus enable the eyeliner to be put easily on the brush, should not make the skin feel tight, and should remain even and last well. It should also be highly safe. Care is needed because some polymer emulsions on the market contain types of surfactants, anticorrosives, preservatives and monomers which would be undesirable for cosmetics. Attention must also be paid to differences in regulations from country to country. Other constituents are chosen with the same degree of stringency but, in aqueous systems, it is easy for them to interreact chemically and coagulate, making pigments prone to precipitation. Freezing may cause irreversible changes so severe high and low temperature tests should be carried out. Furthermore, because it is so easy for microorganisms to multiply in aqueous systems, attention must also be paid to sterilization during manufacturing. Polyhydric alcohols prevent freezing and assist in preservation. There is also the non-film type water-based liquid-form eyeliner which contains water soluble polymers and triethanolamine salts of higher fatty acids but no polymer emulsion. As the points for attention are the same as for the film type, an explanation is not given. Although this type is not water-resistant, like the peel-off film type, its advantage is that there is little feeling of tightness in the skin, making it feel more comfortable. The brush-pen and felt pen types are special forms of eyeliner. With them a thin, natural line can be drawn and they are easy to use even by people unaccustomed to using cosmetics. Typical formula 2. Felt pen type eyeliner Pigment: Dispersant:

Carbon black Polyoxyethylene(10)dodecyl ether

% 5.0 2.0

Makeup cosmetics 393

Humectant: Purified water: Preservative: Perfume:

Glycerin

10.0 83.0 q.s. q.s.

Manufacturing procedure After dissolving the dispersant in the water, add the carbon black and grind in a ball mill. The ratio of powder to water, size of the ball and quantity ratio between the powder base and the ball will greatly affect the grinding efficiency. Add the preservative and perfume to some purified water and use this to dilute the pigment dispersion produced by grinding. The special feature of this eyeliner is its extremely low viscosity which prevents clogging of the brush tips and the felt pen. For ease of application, eyeliner must have a low viscosity. As a guide, the viscosity should range from several to 10 cps. In order to lower the viscosity of the contents, techniques for inhibiting pigment precipitation are required. In accordance with Stokes Law, if the viscosity is constant, we should use pigments with lower specific gravities, and reduce the size of the pigment particles. In this respect, carbon black, Prussian Blue and organic pigments are often used because they have low specific gravities, they are easy to grind and have good coloring. In the product design, polymer emulsions used in the formulations for mascaras and liquid eyeliners are added to give water resistance and prevent smudging. An example of equipment suitable for the grinding is the ball mill. The pencil type is much used because of its ease of use. As its formulation is similar to that of the eyebrow pencil, please refer to the section on eyebrow pencils for details of this. In the case of the eyeliner pencil, it is important to make the lead a little finer in order to make the color go on well and give a soft feeling. 2.9A. Mascara^^^ Mascara is used to make the eyelashes look attractive. It can be broadly divided into the following types: f Water-based

{ Liquid form

Nail care

Care of nails and finger tips

Base coat

Fills in the grooves in the nails Improves adhesion

Enamel

Colors the nail

Top coat

Enhances luster, durability

Nail dryer

Speeds up drying and gives a luster to the nail enamel

Enamel remover

Nail care product

i

Base coat

--H

i

Nail enamel

|

Top coat

i

Nail dryer

; Enamel remover

Removes the enamel

Fig. 2.2. Purposes of manicure products and order of using them.

curved and their physical properties vary also. Nail hardness depends on the water content of the nail plate and composition of the keratin forming it. Generally speaking, children have soft nails which have high elasticity whereas adults have harder nails which break more easily^^\ Manicure preparations thus play a very important role in nail treatment and making the nails look more beautiful. 2.10,2. Nail enamel In terms of composition, present nail enamels belong to the nitrocellulose lacquer group. This is the most practical type that has been developed so far. As well as forming a durable film which protects nails, nail enamel makes them look more beautiful and is thus an indispensable part of modern beauty treatments. Nail enamel has come into common use because it easy to use and gives a nice luster to the nails. It would be very difficult to apply color to the nails using powders or pastes. 2.10.2.1. Quality requirements for nail enamel (1) It should have a viscosity permitting easy application to the nails. Table 2.7. Types of nail care product and their functions Product Nail treatment Cuticle remover Nail guard Nail polish Nail bleach Nicotine remover

Function • • • • • • • •

Supplies oil to compensate for water and oil removal by solvents Has humectant effect Tidies up the cuticle Reinforces the nail Prevents splitting and breaking Makes the nail surface smooth and gives it a luster Whitens the nail Removes nicotine

400 New cosmetic science

(2) (3) (4) (5) (6)

It should dry quickly (3-5 min.) and form an even film. The film should not be cloudy or have pin holes in it when dry. Pigments should be evenly dispersed and the prescribed color and luster should be maintained. The nail enamel should adhere well and not come off during daily activities. It should be easy to remove with enamel remover and come off cleanly. It should not damage the nails or be toxic to them.

2.10.2.2. Main ingredients of nail enamel The main ingredients of nail enamels satisfying the above requirements are listed in Table 2.8. Film formers. The best film former for nail enamel is nitrocellulose. Regarding the quality of nitrocelluloses in current use, the viscosity of most of them ranges from 1/21/4 s and the nitrogen content from 11.5-12.2%. They dissolve easily in ester and ketone solvents. The physical properties of the films formed also make them suitable for use in the paint industry. Needless to say, as the presence of free acid will have a deleterious effect on nail enamel products, the nitrocellulose must be refined. Furthermore, when handling nitrocellulose, care must be taken to keep it away from naked flames and sources of heat. Resins. Resins are an essential ingredient of nail enamel. By itself, nitrocellulose is lacking in terms of adhesion and luster. When used together with nitrocellulose, resins greatly enhance the adhesion and luster. Examples of resins in general use are alkyd resins, sulfonamide resins, sucrose resins and acrylic resins. In the selection of resins, attention must be paid to their interaction with coloring agents, compatibility with nitrocellulose and solubility in the solvents. Plasticizers. Plasticizers are used to give flexibility and durability to the film of enamel. In earlier times, castor oil and camphor were used for this purpose but nowadays, citric acid esters such as acetyl-tributyl citrate are more widely used. However, as camphor is such an effective plasticizer for nitrocellulose, it is still in use today. The required qualities for plasticizers are as follows: (1) They should have good compatibility with solvents, nitrocellulose and other resins. (2) They should be only slightly volatile and give plasticity to the enamel film. (3) They should be stable and not produce a bad smell. Table 2.8. Main ingredients of nail enamels^^^ Film forming ingredients

Solvents

— — Film formers — Resins — — Plasticizers — 1— Active solvents — Couplers or latent solvents — — '— Diluents — Coloring materials

Coloring agents '— Pearly pigments Suspending agents —— Thickeners

Nitrocellulose Alkyd, acrylic, sulfonamide resins, etc. Citric acid esters, camphor, etc. Ethyl acetate, butyl acetate, etc. Isopropyl alcohol, butanol, etc. Toluene, etc. Organic pigments, inorganic pigments, dyes, etc. Synthetic pearly pigments, natural fish scales, aluminium powder, etc. — Organic cation-modified clays

401

Makeup cosmetics Table 2.9. Types of solvent for nail enamel Solvent

Solvent type Low boiling point (up to 100°C) Active solvent Can dissolve nitrocellulose by itself

Medium

boiling

point (100~140°C) High boiling point (140~170°C) Very high boiling point (140-^170°C)

Function (in enamel)

Acetone, ethyl acetate, methylethyl ketone

Reduces viscosity speeds up drying

Butyl acetate, cel- Ester solvent losolve, methylisobutyl ketone

Prevents cloudiness giving fluidity

Ethyl lactate, dia- Ketone solvent cetone alcohol, cellosolve acetate

Enhances adhesion

Butylcellosolve, carbitol

Prevents cloudiness

Couplers or latent solvents

Has affinity for nitrocellulose but no dissolution capacity by itself

Diluents

No ability whatso- Toluene, xylene ever to dissolve nitrocellulose by itself

Ethyl alcohol. butyl alcohol and other alcohols

fluidity

and

by

and

Alcohol solvents

Mix with active solvent to enhance dissolution Improves feeling on use

Hydrocarbon solvents

Mix with active solvent to enhance ability to dissolve resins Regulates feeling on use

(4) They should be compatible with the pigments used. (5) They should be non-toxic. Attention should be paid to these points in deciding on a suitable plasticizer and the amount to be used. Solvents, Solvents used in nail enamel must dissolve nitrocellulose, resins and plasticizers, their viscosity must be able to be adjusted to give the appropriate feeling on use and they must have a suitable rate of vaporization. If the solvent dries too quickly, this will produce pin holes and brush marks will remain, which will affect the appearance of the finished film. Furthermore, solvents whose latent heat of vaporization is very high will cause cloudiness. Therefore, attention must be paid to all of these points. As there is no one solvent which satisfies all of the requirements regarding pin holes, cloudiness, drying rate and feeling on use, a mixture of different solvents is normally used. Such solvents can be broadly divided into the categories shown in Table 2.9. Coloring agents, colors and pigments. Dyes such as Rhodamine B, organic pigments such as Lithol Rubin BCA and inorganic pigments such as titanium dioxide, are used to give a sense of opacity and an attractive color to the finished manicure film. Natural fish scales and synthetic pearly pigments are also used to give a good appearance to the finished film. Suspending agents. Suspending agents are used to enhance the stability of the dispersion for nail enamels using inorganic pigments like titanium dioxide and larger pearly pigments. The suspending agents normally used are organically modified clays^^) which

402

New cosmetic science

prevent precipitation by making the enamel base thixotropic. Organically modified clays are made by exchanging the ions between layers in a clay like bentonite, for organic cations, which makes it lipophilic and easier to disperse in the solvent. Typical formula. Nail enamel Nitrocellulose (1/2 s) Alky d resin Acetyl tributyl citrate Ethyl acetate Butyl acetate Ethyl alcohol Toluene Pigment Suspending agent

% 10.0 10.0 5.0 20.0 15.0 5.0 35.0 q.s. q.s.

Manufacturing procedure Add the pigment to a mixture containing part of the alkyd resin and part of the acetyl tributyl citrate, kneading well together (pigment component). Make a solution of the other ingredients and add the pigment component to this, mixing well to form a uniform dispersion. Of particular importance in the manufacturing process are, carrying it out in a sealed container to prevent evaporation of the solvents, and doing it away from naked flames and sources of heat. Recently, W/O emulsion nail enamels have also been developed^^\ There are base coats for filling in the grooves in nails and improving adhesion, and top coats which are applied on top of the enamel to enhance luster and durability. With the exception of the pigments and suspending agents, they are composed of basically the same ingredients as nail enamels but modifications have been made to enhance their functions. 2,10.3. Enamel remover Enamel remover consists of a mixture of solvents capable of dissolving nitrocellulose and resins. There are types which contain moisturizers and water to replenish the moisture and fat removed by the solvents, and there is also a cream-type enamel remover. Typical formula. Enamel remover Acetone Ethyl acetate Butyl acetate Lanolin derivative Purified water Dye Perfume

% 66.0 20.0 5.0 1.0 8.0 q.s. q.s.

As the ingredients of enamel remover are highly inflammable it is necessary to take adequate precautions against naked flames during manufacture.

Makeup cosmetics 403

2.10.4. Nail treatment When nail enamel and enamel remover are used repeatedly, it is important to remember to take care of the nails and the finger tips. Products referred to as nail treatments are used for this purpose. There are milky lotion and cream types and one in a pencil-shaped tube which is particularly easy to use. They are most effective when used before going to bed, after removing the enamel from the nails, putting the hands in warm soapy water and drying them completely. The frequency of use depends on the condition of the nails. It is a good idea to use nail treatment 2-3 times a week.. Typical formula. Nail treatment Stearic acid Microcrystalline wax Petrolatum Hydrogenated lanolin Liquid paraffin Polyoxyethylene(5)oleate Propylene glycol Triethanol amine Clay Purified water Preservative Perfume

% 2.0 3.0 7.0 2.0 22.0 2.0 5.0 1.0 0.3 55.7 q.s. q.s.

Manufacturing procedure After dissolving the propylene glycol and triethanol amine in the purified water, add the clay and make a uniform dispersion, heating to 70°C (water phase). Mix the other ingredients, heat to dissolve and maintain at 70°C (oil phase). Add the oil phase to the water phase to make the preliminary emulsion and then use a homogenizing mixer to achieve a uniform one. After making the emulsion, cool to 30°C while stirring. 2.10.5. Other products (1) Cuticle remover. Cuticle remover is a cosmetic product used to remove the old cuticle and dirt on the nail plate, in order to keep the nails looking attractive. One type contains weakly alkaline ingredients such as sodium phosphate and triethanol amine, while another contains a scrub powder so it has a physical mode of action. Typical formula. Cuticle remover Triethanol amine Glycerin Purified water Perfume

% 10.0 10.0 80.0 q.s.

Special care must be taken to ensure that cuticle remover does not go into the eyes, on to other parts of the body or on to clothing.

404

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(2) Nail guard. This is a cosmetic product which strengthens thin and soft nails, prevents cracking and chipping and makes the enamel last longer. In one type, polymer powders (as strengthening agents) and nylon fibers are added to the enamel base coat (3) Nail drier. Nail drier speeds up the drying of nail enamel and gives it an extra luster. It is usually in aerosol form and consists of a small amount of nail drier base and a large amount of propellant. Various oils may be used in the nail drier base. (4) Nail polish. Nail polish is applied to the nails and then they are polished in with chamois leather to keep them in a healthy condition by filling in the grooves, making them smooth and giving them a shine. It also makes the enamel film more durable and gives the nails a greater luster. The main ingredients are inorganic powders and a small quantity of pigment is used to give the nails a healthy color. It comes in powder, paste or compact form. (5) Others. Examples of other manicure products are nicotine remover and nail bleach, a similar product, for making the nails whiter. Such products are not seen on the market any more.

References 1. Sugiura, Ueda, ed.: Modern Cosmetic Science, Hirokawa Shoten, 1974. 2. Kobo, T., ed.: Modern Products Encyclopedia, Toyo Keizai Shimposha, 1986. 3. Soc. Cosmet. Chem. Jpn., ed.: Latest Developments in Cosmetic Science, enlarged and improved edition, Yakuji Nipposha, 1988. 4. Bourgeois, C : Chimie de la beaute, Que sais-je No. 901, Presses Universitaires de France, Paris, 1970. 5. Schrader, K.: Grundlagen und Rezepturen der Kosmetika, Hiitig Buch Verlag GmbH, Heidelberg, 1989. 6. Balsam, M. S. et al.\ Cosmetics Science and Technology, Vols. 1,2, 2nd edn., John Wiley and Sons Inc., New York, 1972. 7. Schlossman, M. L.: Cosmetics and Toiletries, 100, 33-40 (1985). 8. Sperandio, G. J.: Am. Perfum. Cosmet., 79, 75-77 (1964). 9. Kimura, S. et al.: Cosmetics and Toiletries, 107, 59-68 (1992). 10. Saito, Murai, Date: Fragrance J., 73, 10 (1985). 11. Hempel, M.: Seifen-Ole-Fette-Wachse, 120, 5, 262-264 (1994). 12. Kuhni, M. et al.: Parfumerie und Kosmetik, 75 (9), 581-582, 587 (1994). 13. Tanaka, S., Kumagaya, S.: Cosmetics and Industry, 40 (6), 115 (1987). 14. Faulkner, E. B.: Cosmetics and Toiletries, 107, 45-49 (1992). 15. Hofmann, B.: Seifen-Ole-Fette-Wachse, 116 (8), 299-306 (1990). 16. Charlet, E.: Kosemetik International, No. 2 (64), 69-70 (1991). 17. Schlossman, M. L.: Cosmetics and Toiletries, 105, 53-64 (1990). 18. Tichy, H. S.: Seifen-Ole-Fette-Wachse, 117 (10), 389-392 (1991). 19. Brown, M. W. et al.: Cosmetics and Toiletries, 105, 69-73 (1990). 20. Griebler, W. D.: Seifen-Ole-Fette-Wachse, 113 (20), 765-771 (1987). 21. Tichy, S.: Seifen-Ole-Fette-Wachse, 118 (10), 612-620 (1992). 22. Bews, I. C. R. et al.: Am. Perfum. Cosmet., 79, 89-103 (1964). 23. Veitch, J.: Parfumerie und Kosmetik, 75 (2), 92-99 (1994). 24. Fukui, H. et al.: Cosmetics and Toiletries, 96, 3 7 ^ 6 (1981). 25. Kuwahara, Ando: Pigments and Paints, p.26, Kyoritsu Zensho, 1972. 26. Higashikubo, K.: Fragrance J., 14 (5), 60-66 (1986). 27. Jimbo, M., ed.: Powders, their Functions and AppUcations, p. .301, Japan Standards Association, 1991. 28. Kobayashi, S.: Fragrance J., 20 (1), 107-113 (1992). 29. Yoneyama et al.: Patent: Tokkaisho, 61-293904, Japan.

Makeup cosmetics 405 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67.

Someya et al:. Patent: Tokkaihei, 2-142716, Japan. Nowak, G. W.: Am. Perfum. Cosmet., 7 9 , 4 1 ^ 5 (1964). van Ham, G. et al.: Fette, Seifen Anstrichmittel, 76 (5), 223-228 (1974). Scrofani, C. et al.: Cosmetics and Toiletries, 108, 65-68 (1993). Krueger, C.: Cosmetics and Toiletries, 96, 35-36 (1981). Dweck, A. C : Cosmetics and Toiletries 96, 29-32 (1981). Dweck, A. C. et al.: Cosmetics and Toiletries 96, 61-72 (1981). Reuschl, W.: Parfiimerie und Kosmetik, 75 (2), 86-91 (1994). Haruyama, Y.: History of Makeup, pp. 22, 30, 107-125, Heibonsha, 1976. Inubai, T. et al.: Everything You Need to Know About Cosmetics for Your Beauty, pp. 62, 69, 86-88, International Commercial Press, 1978. Haruyama, Y. Collection: The History of Cosmetics in Our Daily Lives, pp. 30-36, 45, Heibonsha, 1987. Pola Culture Research Institute Collection: Japanese Cosmetic Tools and Heart Patterns, pp. .30, 40-42, Pola Culture Research Institute, 1989. Makabe, J.: Safflower Reverie, Yamagata Shimbunsha, 1978. Uemura, R.: Dyeing and Weaving in Life, No. 2, pp. 37-39, Senshoku to Seikatsu Sha Corp., 1973. Coloring Materials Association: Coloring Materials Technology Handbook, p. 318, Asakura Shoten, 1989. Ikeda, T.: Fragrance J., 18 (8), 41-45 (1990). Ikeda, T.: Fragrance J., 20 (4), 14-21 (1992). Patent: 1374048, Japan. Patent: 1307890, Japan. Patent: Tokkaisho, 56-45045, Japan. Patent: Tokkaihei, 03-76284, Japan. Patent: 1461702, Japan. Patent: Tokkohei, 01-287011, Japan. Nakajima et al: Patent: Tokkosho, 61^2328, Constituents of OilAVater Emulsions, Japan. Fishbach, A. L.: Am. Perfum. Cosmet., 79, 47-50 (1964). Kosmetik International No. 4, 58-59 (1992). Wimmer, E. P. et al.: Cosmetics and Toiletries, 107, 115-120 (1992). Kunzmann, T.: Seifen-Ole-Fette-Wachse, 103 (1), 5 ^ (1977). Schlossman, M. L.: Cosmetics and Toiletries, 96, 51-54 (1981). Grizzo, S.: Cosmetics and Toiletries, 92, 63-65, (1977). Kosmetik International No. 3, 65-68 (1995). Achten, G.: Am. Perfum. Cosmet., 79, 23-26 (1964). Kosmetik International No. 5, 40-41 (1995). Yamazaki, A.: Nail Care and Nail Art, pp. 6-11, Nagaoka Shoten, 1986. 25 ans Elegance Book No. 12 — Cosmetics 2 (supplementary issue), Fujin Gaho Sha, 1988. Yamazaki, K.: Fragrance J., 14 (4), 16-20 (1986). Ikeda,T., Kobayashi, T., Tanaka, C , Fujiyama, Y., Ozawa, T., Mitsui, T.: J. Soc. Cosmet. Sci. Jpn., 22 (1), 25-34 (1988). Yamazaki, K., Tanaka, M.: J. Soc. Cosmet. Chem. Jpn., 25 (1), 33-50 (1991).

3

Hair care cosmetics

3.1. Hair cleansing cosmetics Hair cleansing cosmetics consist of shampoo and rinse (rinse-off conditioner) which remove dirt from the scalp and hair, and keep it in a clean condition. The washing of a textile has been completed once the dirt has been removed and the textile has been dried but in the case of the human body, it is not just enough to remove the dirt: the feeling one has during and after washing the hair, and the care given afterwards, are also very important. Therefore, after washing the hair with a shampoo, a rinse is used to make it easy to manage. The type of dirt, nature of the detergent used, temperature at the time of washing and the physical forces acting, are all involved in the hair washing process. The dirt consists of sebum secreted by the scalp, sweat residue, flakes of superfluous horny layer flakes (dandruff), dust and other external matter, and the residue from hair care cosmetics which have fulfilled their designed purpose. In order to remove such dirt, anionic, amphoteric and nonionic surfactants are normally used as the detergents for shampoos. The dirt is removed by the penetration, emulsifying and dispersive actions of surfactants. First of all, the shampoo penetrates into the interface between the dirt and the surfaces to be washed (scalp and hair) and weakens its adhesion. As a result, the dirt can be easily removed by physical forces and is taken off by the water. The dirt is broken up into fine particles, uniformly dispersed in the water and the surfactant that adsorbed the dirt prevents it from adhering to the hair and scalp again. The lather of the shampoo plays a very important role because it keeps the shampoo in the hair, makes the hair easy to wash by easing the passage of the fingers through it and has a cushioning effect which prevents the hairs from getting tangled up with each other. There is not necessarily a correlation between lathering ability and cleansing ability, however. For instance, nonionic surfactants do not have much lathering ability but they are very good cleansers because of their strong emulsifying capability. Nowadays though, shampoos are not just for removing dirt from the hair and scalp, and they have been greatly diversified. There are now conditioning shampoos which prevent damage to the hair during washing, medicated shampoos which prevent dandruff and itchiness, and shampoos which incorporate rinses. If a rinse is used after washing the hair, its main ingredients of a cationic surfactant and oils are adsorbed by the hair and stay on it when the rinse has been washed off to improve the condition of the hair. Among hair rinses, there is a special type known as 406

Hair care cosmetics 407

"hair treatment" or "hair pack" which protects the hair more. It is used in the same way as other rinses. 3.1.1.

Shampoo

Shampoo is a hair-wash cosmetic used to remove dirt from the scalp and the hair, treat dandruff and itchiness and maintain the hair in a clean and beautiful condition. In order to do this, it must have an appropriate level of cleansing power which is sufficient to remove all the dirt but will not remove too much sebum, which is very necessary for the scalp and hair. There are a great variety of shampoos which, in addition to their main function of cleansing, have added value in the form of conditioning, luster enhancing and styling capabilities. These shampoos come in many different types and forms. 3.1.1.1. Qualities required of shampoos and their categories Although shampoos have many different functions they must all have the following qualities. (1) They must have an appropriate cleansing ability. (2) They must produce a lasting, rich, creamy lather. (3) They must protect the hair from friction damage during washing. (4) The hair must have a natural luster and an appropriate softness after it has been washed. (5) They must be very safe with respect to the scalp, hair and eyes. Formerly, soap was used for washing the hair. Then in the 1930s, as a result of advances made in the development of synthetic detergents, alkyl sulfates started to be used as detergents for shampoos in America and Europe. In Japan, powder and jelly form shampoos based on alkyl sulfates came in to use from 1955 onwards. With the introduction of alkyl ether sulfates beginning in 1965, the use of shampoo spread on a grand scale and liquid shampoo became the main type. From its external appearance, shampoo is divided into two types — a transparent liquid type and a high grade opaque liquid type, in which an opacifying agent is added. Some types of shampoo have additional functions. Examples are given below. (1) Oil shampoo and cream shampoo, in which an oil component has been added to enhance the feeling obtained after the hair has been washed. (2) Conditioning shampoo which prevents damage to the hair during washing. (3) Anti-dandruff shampoo which is very effective in preventing dandruff and itchiness. (4) Mild shampoo which is less irritating to the scalp and the hair. (5) Two-in-one type shampoo incorporating a rinse function as well (reduces friction on the surface of the hair, prevents static electricity, protects the hair, etc.). (6) Shampoo having a combination of the above functions. 3.1.1.2. Main ingredients of shampoo. Shampoo consists of foaming detergents and various additives. The foaming detergents used are anionic, amphoteric and nonionic surfactants.

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science

(1) Anionic surfactants. Anionic surfactants are used very widely as a foaming detergent for shampoo. The major ones are as follows: Alkyl sulfates (AS) and polyoxyethylene alkyl ether sulfates (AES) ROSO.M

AS

RO (CII,CII,())n S(),M

AKS

M : Sodium etc

Owing to their low price and high availability, sodium, ammonium and triethanolamine salt surfactants are the ones most used in shampoo. These surfactants are neutral, have high cleansing power, are stable in hard water and have a lathering ability satisfying a shampoo's needs. Very often AS and AES are used in combination. The former is low in price and produces a good lather while the latter is more hydrophilic, very soluble in water at lower temperatures and less irritant. The lathering, irritancy and hydrophilic nature can be adjusted as appropriate by varying the length of the alkyl and polyoxyethylene chains. Acyl methyl taurates (AMT) RCONCH2CH2SO3M CH3

M *. Sodium etc

Attention has been focused on acyl methyl taurate because its structure is similar to that of taurocholic acid, a naturally occurring surfactant found in the bile of humans and animals and it is now used as a highly safe surfactant. As the hydrophilic group is sodium sulfonate, it has high acid and hard water resistance. Based on the results of research carried out on the skin irritation, protein denaturation, adsorption to protein and cleansing power aspects of anionic surfactants^^ we can say that acyl methyl taurate is superior to other surfactants in that it does not readily leave a residue on the scalp and hair, it does not denature proteins, which are, of course, the main constituents of the scalp and hair, and it does not disrupt the normal metabolism of the skin. //-Acyl glutamate RCONHCOOM CH.CH.COOH

M:Sodmmetc

There are also amino acid surfactants, whose raw materials are amino acids, and they have sodium and triethanolamine salts. Compared to AS and AES, they have a somewhat lighter lather and they are very mild in terms of irritation with respect to the skin and the eyes. Soaps are also used as cleansing agents but they are not very good for shampoo because metallic soaps form with calcium and magnesium from water and the human body making the hair stiff. (2) Amphoteric surfactants. Amphoteric surfactants are used in combination with anionic surfactants to make the shampoo safer and to enhance thickening and so forth. They are also used on their own.

Hair care cosmetics 409 Betaine type Alkyl betaine

CH3

I

R-N^-CH2C00-

I

CH3

Alkylamide betaine CHs

I

RCONH(CH2)3 N+-CH2COOI CH3

Imidazolinium betaine ^N

R-