New cosmetics patch test series: A proposal.

Background: Contact dermatitis to cosmetic products is a common condition. It is likely the most frequent reason for performing patch tests because many substances used in cosmetics are potent allergens. Cosmetic contact dermatitis most frequently affects the face. Patch test series need to be continuously revised to identify outdated and emerging allergens. The aim of this study is to propose a reformulation of the patch test series for cosmetics. The list of European Surveillance System on Contact Allergies was initially used to select the allergens. Publications in PubMed from the last 10 years were sought, showing the frequency of positive reactions to cosmetic allergens that were tested as part of a baseline series or cosmetics series. Subsequently, large international databases evaluating retail products were consulted to verify if these substances were present in cosmetics, because the relevance would be their presence in commercially sold cosmetics. It was adopted a threshold of 0.3% positive patch test reactions for including a substance in cosmetics series. It was deleted those present in the baseline series (Associação Brasileira de Alergia e Imunologia), fragrances, and allergens limited to hair products. It is believed that choosing too few allergens may result in the non-identification of relevant allergens and treatable cases. On the other hand, testing a series with many allergens is time-consuming and more costly. Therefore, it seems appropriate to create cosmetics series with 20 elements.