SKIN REACTIONS TO COSMETIC PREPARATIONS 25 sweat onto the skin. 20% aluminium salts at pH 2-3 are skin irritants, and damage clothes, and the acid condition may be produced by hydrolysis. (b) Formalin An effective anhidrotic but unfortunately, owing to the use of urea- formaldehyde for crease resistant fabrics, an increasing number of people are becoming sensitized. Formalin is leached from the fabric by axillary sweat, producing dermatitis. There is, therefore, some danger in using formalin in this situation as an antiperspirant. (c) Zirconlure Zirconium used in 10% strength in sticks as a deodorant (35) has pro- duced granulomata in the axillae. The stick was applied after shaving. The granuloma reaction is an allergic one increased by the use of soap or hexa- chlorophene. Intradermal testing reproduced granulomata. Deodorants Aluminjure chloride added to decomposed apocrine sweat renders it immediately inoffensive. Chlorophyll, on the other hand, in daily dosage of 600 mg by mouth was ineffective as a deodorant (36). 20% Sodium bicar- bonate in talc combines with the fatty acids formed by decomposition, and so renders them inoffensive. Contact dermatitis may be seen from rubber dress shields, a!uminium salts, formalin, perfume, preservatives, antibacterial agents and glyceryl monostearate used as an emulsifying agent. Folliculitis or hidraderdtis suppurativa, indolent abscess formation, in the apocrine glands may result from duct blockage by antiperspirants, friction, tight clothing, and due to shaving the axillary hair to prevent retention of the secretions. I)EPILATORIES In addition to shaving, electrolysis and diathermy, superfluous hair may be removed by abrasives, wax and chemical action. Wax is applied either as a stick of wax and rosin with perfume which is warmed and then pulled off when cool, or on fabrics as a sticky plasticized rosin adhesive, sometimes containing benzocaine to make the epilation less painful. Apart from contact dermatitis from the bases and perfume there may be a traumatic infection of the hair follicles (folliculitis). Seborrhoeics are particularly likely to develop infection. Abrasives are suitable .only for downy hair growth, and may produce irritation and folliculitis.

JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Chemical depilatories Sulphides Barium is considered to be too dangerous to use in this country. The sulphides of sodium and potassium are unsuitable, being unstable and in- effective. 2-3% calcium sulphide and 5-10% strontium sulphide are used. Alkaline mercaptans 4-10% Calcium thioglycolate at pH 10-12.5 may be used. A combined depilatory and detergent has been used for surgical preparations with little ill effect. All depilatories, apart from the risk of contact dermatitis, are likely to irritate sensitive skins, and many women find they cannot use them, pre- ferring shaving or electrolysis. Of the satisfied users, nothing is heard. THE NAILS The nails are resistant to contact dermatitis but nail dystrophies are seen, due to damage or dermatitis of the nail fold or nail bed, or infection (paronychia). Undercoat dermatitis This is a diffuse or punctate yellow to black discolouration of the nail, with separation of the distal 2/3rd of the nail plate from the nail bed, due to hyperkeratotic thickening of the nail bed. Occasionally, the finger ends are red and sore, or there is some paronychia, otherwise the changes are entirely subungual. The causal agent is either synthetic rubber or phenol formaldehyde resin in methyl ethyl ketone, the nail bed being affected either by undercoat drips or dialysis through the nail plate. The sensitivity develops after continuous use for 4 to 12 weeks or longer. Plastic nail dermatitis Self-curing acrylic nails, formed by polymerization of methyl methacrylate monomer and polymethyl methacrylate powder with an organic peroxide and an accelerator. The liquid monomer has been proven to be a sensitizing agent, producing dermatitis of the fingers of the manicurist, severe eczematous reactions on the perionychial structures with nail dystrophy, and on the finger, the face and eyelids of the recipient. Pressure on nails causes damage by occlusion, and the free exchange of moisture between nail aI•d atmosphere is prevented. The nail, like the stratum corneum of the skin is kept supple by water, which can saturate keratin up to 30%.