P13 Results of patch testing with patients’ own cosmetics and toiletries

Abstract

Patch testing with materials brought in by the patient is useful to identify the cause(s) of current allergic contact dermatitis (ACD). However, little is known (i) on the contribution of such tests to diagnostic success and (ii) on the spectrum of contact allergens associated with ACD to certain product categories. Between 1998 and 2002, 5911 out of 48381 patients patch tested in the centres of the IVDK (http://www.ivdk.org) have been tested with own cosmetics and toiletries in addition to commercial allergens. These were manually assigned to 26 categories, based on a EU classification (annex I to 76/768/EEC), which was further refined. As illustrative example, data on “Bath and shower preparations” are presented: out of 1333 patients tested with a total of 2336 single patches (1102 with 1%, 391 with 10% and 280 with 0.1% in water, remainder with other preparations, depending on the actual kind of product), 71 had positive reactions at the D3 reading. Only in 46 of these, reactions to potential cosmetic ingredients, tested as commercially available allergens, were observed. Among these, fragrance mix (30.0% vs. 12.9% in those not reacting positively to this product category), Myroxylon Pereirae resin (18.6% vs. 8.4%) and some biocides like MCI/MI (11.4% vs. 1.8%) and methyldibromo glutaronitrile + phenoxyethanol (12.1% vs. 5.3%) were the most common allergens. In conclusion, patch testing own products – although not without pitfalls – may (i) help to correctly diagnose ACD and (ii) give important hints on the occurrence of allergens in a particular type of (cosmetic) product.