J. Soc. Cosmet. Chem. 26 323-335 (1975)¸ 1975 Society of Cosmetic Chemists of Great Britain Estimation of the general incidence of specific lanolin allergy E. W. CLARK* Synopsis--The literature pertaining to LANOLIN HYPERSENSITIVITY is critically reviewed with reference to relevant definitions, exposure to lanolin, limitations of test methods, inherent exaggeration of test results, AUTOXIDATION, multiple sensitivities, selection of test subjects and the distinction between secondary and specific lanolin ALLERGY. Using recent data relating to 8.25X 105 population in three European countries the incidence of specific lanolin allergy amongst the general population is calculated to be no more than 9.7 per 10 ø and probably considerably less. Scope. The object of this work is not to review an exhaustive list of all known literature on the subject, since several summaries and commentaries have already been given (1), (2), (3). It is to study the more representative, extensive and significant publications and to draw from this detailed evidence a valid conclusion about the general incidence of specific lanolin allergy. This has not previously been attempted. INTRODUCTION Cases of allergy or hypersensitivity to lanolin have been recorded over a period of approximately 50 years. Although the absolute incidence of this hypersensitivity does not appear to be increasing (2), over the last decade particularly the subject has become more prominent in the medical and scientific press, yet the vast majority of this work has been concerned not with the general public but with relatively small groups of patients attending skin hospitals, including patients having severe symptoms such * Westbrook Lanolin Company, Bradford, Yorkshire. 323

324 JOURNAL OF THE SOCIETY, OF COSMETIC CHEMISTS as leg ulcers and therefore abnormal sensitivity. Such work cannot be equated to the overall general situation. Since lanolin is a widely used ingredient, not only of products applied to the skin such as cosmetics and ointment bases, but also of many other common household commodities, it is important to establish as far as possible the incidence of hypersensitivity, or more particularly of primary specific allergy, to the substance amongst the general population. Hardly any substance at all can be said to be completely non-allergenic. Even foods such as milk, eggs, fish and fruit, also common metals such as nickel used in coinage and clothing attachments, provok e a small but real incidence of allergy. Clearly, if every substance which was known to have elicited even a single case of allergy over its whole history were to be regarded as suspect, there would be little left for people to eat, drink or wear. For any substance in common use, therefore, the incidence of allergy to that substance should be weighed against its benefits to the whole com- munity to decide whether the incidence is acceptable or not. The benefits of lanolin as a unique combination of emollient for the skin and W/O emulsifier have been proven beyond doubt by subjective evidence of the practical results of its use over a period of centuries (1), and by its inclusion in most national pharmacopoeiae for many decades. Lanolin is more readily miscible with sebum and more penetrating than petroleum jelly (2), and a very versatile and useful carrier with good release properties for certain medicaments (4), (5). It is widely used in industrial hand protec- tives ('barrier creams') (6), and has been specifically recommended for this purpose (7) to prevent the development of dry skin with consequent increased risk of developing dermatitis. Other important applications of lanolin are instanced later, and it can be seen, therefore, that we are dealing with a substance which is of considerable value both to medicine and also to the community as a whole. DEFINITIONS It is necessary to define the term 'lanolin' since some publications on the subject of allergy have referred to 'lanolin derivatives' without being specific (8), (9), (10). To assme identical dermatological behaviour by lanolin and all its chemically modified derivatives is clearly wrong in the absence of proof. Indeed, several workers have established distinct differ- ences in allergic incidence between various derivatives (11), (12).