SKIN REACTIONS TO COSMETIC PREPARATIONS 11 (3) Pigmentation Hypo- Hyper- (4) Hair damage. (5) Folliculitis. (6) Granuloma formation. (7) Nail damage. Eczerna dermatitis This is by far the commonest type of reaction, consisting of erythema and oedema with or without papules, vesicles and bullae, according to degree and followed by scaling. There is usually itching and burning. The area affected is usually that to which the cosmetic is applied, e.g. lipstick, but may affect distant but more sensitive areas, e.g. eyelids in nail varnish dermatitis. Thickening, pigmentation or sepsis may be produced by scratching or rubbing. A latent constitutional dermatitis or dermatosis may be provoked, complicating the original picture at any stage and becoming chronic when the original reaction has cleared. Cross sensitization may cause complications by producing apparently unrelated exacerbations, and by seemingly unjustified chronicity. Unex- pected areas may be affected, e.g. in mercury sensitivity the area exposed to a lotion may be affected, yet a more generalized reaction may be provoked by taking mercury by mouth. Some areas are less sensitive than others, notably the scalp, palms, soles and mouth, nails and nail folds, whereas the eyelids, lips and finger clefts, neck and cheeks are relatively more sensitive. Some irritants, e.g. lotions, scents, etc., tend to drip and reactions appear in streaks below as well as at the site of application. The population varies in its ability to develop a sensitivity, the so-called index of sensitivity. It is interesting that 2-5% of Americans are sensitive to wool and fat, and 2% to aluminium acetate and phenol. Chemicals also vary in producing sensitivity in an individual by the so-called sensitizing index. This is high for pphenylene diamine, and low for henna. In any given cosmetic preparation the offending substance may be in the active principal, the adjuvants, the vehicle or base, the perfume, dye or preservative. An individual may become sensitive to a cosmetic at first exposure, or after years of use or because some new inadequately tested "improvement" has been added, e.g. tetrachlorosalicylanilide in soap. Few cosmetics can claim to be non- or even hypo-allergic.

12 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Emulsifying agents The base of most cosmetic preparations is an emulsion. The following agents have produced sensitization: Sodium lauryl sulphate lanolin and its cholesterol derivatives glycerol monostearate Alphakeri (a non ionic emulsifier) triethanolamine. Perfumes Perfumes are compounded from relatively few of the some 5,000 or so smells available. Natural sources.' (1) Plant: The flower, leaves, stems and roots, seeds and bark give resins, essential oils, gums and balsams. (2) Animal: Secretions such as musk, civet and ambergris. (3) Synthetic organic chemicals. To control the volatility of perfume mixtures, fixatives such as gums and balsams (tolu benzoin styrax), benzyl benzoate diethyl phthalate, cinnamic acid esters, are added. Sensitizers include: Ionerie (synthetic violet), balsam of Peru, benzyl alcohol, methyl heptine carbonate (jasmine or violet), cloves, cinnamon, citrus fruits, vanilla, eugenol, heliotrope citronella, pine terpenes, and the fixatives. Perfumes may produce contact dermatitis or pigmentation (see below). Preservatives These are required to prevent growth of bacteria and moulds in cosmetic preparations. Only low concentrations are required, 0.05-1.25% or even more in soaps. Potential irritants: pchloromcresol and pchloroxylenols are usually only irritant in high concentrations. 1-2% hexachlorophene may produce pig- mentation. phydroxybenzoic acid and its esters used as ointment pre- servatives have caused dermatitis (13). Tetrachlorosalicylani!ides have produced dermatitis when used as antiseptics in soaps. Other halogenated salicylanilides may also be sensitizers. Colouring agents (1) Natural pigments: Inorganic mineral oxides, e.g. chrome green and ultramarine (eye make- up), and metallic hair dyes are safe. (2) Animal and vegetable pigments: Henna, chamomile and indigo are safe, but cochineal is a sensitizer.