SKIN REACTIONS TO COSMETIC PREPARATIONS 23 the hormone content is usually too low to be effective. There was no incidence of systemic effect from creams with a maximum potency of 10,000 I.U./oz of vehicle (32). Senile skin in the light exposed areas does absorb water, the collagen becoming hydrated, capillary size is increased and the epidermis is thicker (15). Such change does not occur in the skin of the young and Behrman (33) could find no difference between the hormone cream, and its base alone acting as an emollient. Carcinogenicity has not been proven. THE HAIR Hair growth is stimulated by local inflammation of the hair bearing skin. Growth is seen after sun burn, bacterial inflammation, radioactive emanations, e.g. thorium X, steroids, androgen, and oestrogens. The basis of hair restorers lies in irritation of the scalp by rubefacients and counter irritants. Resorcino!, tar, capsicum, acetic acid, pilocarpine and cantharides all have their disadvantages and dangers. There are no known preparations which will grow new hair. Certain endocrine preparations can stimulate hair growth where hair existed before. Androgens responsible for the growth of hair on the face, chest and limbs of the male, and also for the loss of hair in male baldness (canities) can stimulate hair growth in those areas of the female with disastrous results. It has been claimed that oestrogen preparations, by mouth or applied locally, stimulate regrowth of hair in canities. In the male there are un- desirable side effects, and in the female, mammary enlargement, pigmentation of the face, nipples and body, and uterine bleeding from endometrial hyper- plasia, if the preparations are given in adequate dosage, even by local application. Steroid medication, systemic or by local injection, stimulates hair growth in alopecia areata but the growth usually ceases with the cessation of medica- tion, which cannot be given indefinitely. Thinning of the hair This may be a natural phenomenon, as in ageing. It may occur for endocrine reasons, canities, Addison's disease, pregnancy, etc., during or following a severe illness, and following infection. Temporary fall follows the appropriate dose of radiotherapy, a larger does produces baldness and scalp atrophy, or may be due to drugs, e.g. thallium acetate. Cosmetic procedures, either physical or chemical may produce thinning. Trauma, e.g. rubbing or scratching, will eventually break the hair. So will repeated trauma of tight clips worn in the same place every day or winding too tightly onto curiers at night, waving with tongs at too high a temperature, or frequent brushing with a hard nylon brush. Hair styles such as the pony

24 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS tail, or the tight plaiting adopted by Soudanese women, cause loss of hair, and folliculitis of the mid scalp. Chemicals Repeated washing with shampoos, containing detergents, removes the grease and dries the hair and scalp. In the absence of a protective film of grease, the detergent may attack the keratin of the hair altering its structure the hair becomes brittle and breaks. Excessive greasiness may follow the continued use of detergents or selerdum sulphide, and the exposure is likely to increase in a vain attempt to combat the effects of these agents. Diffuse hair loss has been reported in these circumstances. The remaining hair is dull, dry and brittle. Excessive bleaching or thioglycolate waving produces brittle hair. Infection and granuloma formation Folliculitis or infection of a hair follicle produces hair loss by scarring. Scratching in hairy areas, persistent plucking or close shaving, and the use of chemicals such as mineral oils, tar and mercury, precipitates a folliculitis. DEODORANTS The offensive odours so familiarly described in advertisements are due to decomposition and fermentation of apocrine sweat by bacterial action. Sterile apocrine sweat is odourless, and it has been shown experimentally that hexachlorophene will delay decomposition for 14 days. Eccrine sweat, sterile or contaminated is odourless. The axi!!ae, groins and natal cleft, moist warm hairy folds with plentiful apocrine and sebaceous secretions, form ideal refuges for bacteria, mostly cocii, micrococci and diphtheroids. Deodorants can, therefore, act in several ways: Antiseptic agents Hexach!orophene, tetrachlorosalicylanilide, and tetramethylthiuram- disulphide. The latter two are sensitizers. Mild bacterial lotions, e.g. mercuric chloride, aluminium chloride and formalin. Antibiotics: Blank (34) in a report to the 1959 Committee on Cosmetics condemned the use of antibiotics except as axillary deodorants because more harm than good was likely to follow their widespread use in cosmetics, by in- creasing the sensitivity of the host and decreasing the sensitivity of the bacteria. Antiperspirants (a) AluminJure Salts These are the commonest constituents of antiperspirants, drying the area by provoking keratinization of the duct orifices so preventing discharge of