COSMETICS AND DERMATITIS contact with the antigen and the ment of sensitisation, during ich further application of the to the skin will produce no Obvious reaction. This period is about ten days and may be i shorter or Ionger. We are unable, unfortunately, to rmine in advance which 'sub- ta•nces are likely to produce sensiti- iSation, and except for the azo dyes and the amine intermediate dyes, we are not able to correlate sensitis!ng !properties with chemical structures. .It is therefore necessary to try out a preparation by patch testing several hundred normal people be- one can determine its sensitising { i•":i:Powers. In this respect it is worth •½/•1111:/:remembering that, if a substance produces a skin reaction in at least one in two hundred normal subjects, its cdmmercial development should not be proceeded with until a further test on two hundred more subjects :i}!.::'i:,11 :: has shown that the risk of sensitisa- tion is less than 0'5 per cent. Should this percentage be exceeded, a care- ful review of the composition of the cosmetic should be undertaken, to see which ingredient is responsible for sensitisation, and this should be excluded. Prophetic patch tests are undesirable in industry, however, even though they have been popular in the United States. Patch tests intended. to be carried out by the user at home are unlikely to be done properly, and in any case patch tests require skill and experience in their interpretation. (Continued on page 210) -x • .... CHROMIC ACID //I • PRICKLE / \ 0-.--* .... :'1'"-.'"' C[Lt_ NUCLEUS (-- Figure 5. Theory or sensitisation mechanism. Chromic acid in contact with skin protein on surface of a prickle cell. ELL RECEPTOF• Figure 6 (above): An antibody has been pro- duced at cell surface. Note diagrammatic representation of "complementary fit." Figure 7 (below): Antibody has united with antigen (chromic acid) leading to release of histamine and other substances. HISTAMINE RELEASE •,..r• 209

JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS REVIEWING COSMETICS AS A CLASS Cosmetics as a class are relatively harmless. Most of them are quite innocuous when applied to the skin, as mentioned above, and in practice are responsible for very few cases of dermatitis. Occupational dermatitis due to cosmetics is very rare the chief reason for this freedom from occupa- tional risk is probably to be found in the preponderance of automatic methods used in mixing, filling and packing the various preparations. As far as the user. is concerned, face creams very rarely give trouble except when irritant perfume mater- ials have been incorporated in them ß the same is true of face powders. Permanent waving agents give most trouble. This is due to the fact that they are potent keratolytic agents and therefore tend to damage the horny layer. The oxidation hair dyes are also liable to give trouble, because of their sensitising proper- ties. Allergic dermatitis produced by hair dyes is dramatic in its onset and character, as the case outlined above shows, but it is usually, and fortunately, easy to treat. Lipstick dermatitis is often provoked by exposure to strong sunlight, either by the seaside or in the high moun- tains, and is due to the eosin or similar agent incorporated to give the colour to the lipstick. These substances have photochemical pro- perties and sensitise the individual to the dye in the presence of hght. They may' also, of course, produce dermatitis without the aid of light. 210 Another photodynamic substance used in cosmetics is bergamot oil, and this gives rise to a fairly character- istic brown pigmentation in areas exposed to sunlight. Nail lacquer dermatitis is usually met with on the thirdy keratinised skin around the eyes and on the chin, but rarely on the fingers. Several constituents' of .plastics are known to be sensitising agents and some of the nail cosmetics produce brittleness in the nails with splitting of their free margins. It should, however, be borne in mind that the commoner cause of nail brittleness is the iniudicious use of certain of the newer detergents by the housewife rather than, as is popularly supposed, the nail .varnish solvents although the latter do sometimes give rise to trouble. Rouge is quite innocuous in character' and very rarely provokes signs of dermatitis. Depilatories, on the other hand, are likely, by their very nature, to give rise to trouble if they are not used carefully. The keratin in hair is tougher than that of horny layer of the skin, and as the depilatory has to destroy this keratin, it is likely to damage the horny if it is allowed to remain too longi'i• in contact with the skin. (In clinical practice I prefer to use electrolysis :i}i for depilation, but this is impractical :11i for axilla W hair in women.) An::-! unusual type of dermatitis may::•! follow the use of brilliantine. consists of acne-like lesions, monly seen on the forehead of the?! user and is due to the hydrocarbonsi:/• incorporated in the brilliantine. .•,