Extended fragrance ingredients surveillance study (EFISS)—protocol for a clinical surveillance study on contact allergy to 7 fragrance materials in widespread use but hitherto not systematically patch tested

Contact allergy (CA) is not uncommon in the population, including to various fragrance allergens. If not diagnosed correctly, allergic contact dermatitis (ACD) may ensue, because targeted allergen avoidance is not possible. The primary objective of the study is to estimate the prevalence of CA to seven fragrance materials in patients with suspected ACD across Europe. Based on the outcome, a conclusion will be drawn as to whether present risk management regarding maximum recommended concentrations of each of these, based on quantitative risk assessment (QRA2), is adequate. The planned study is a surveillance study based on consecutive patients, patch tested in 10 European departments of dermatology with a series of allergens as indicated by their personal history, including the European baseline series, supplemented with the seven additional fragrance ingredients. The patch test procedure will follow the guideline of the European Society of Contact Dermatitis (ESCD) with additional standardization procedures. The envisaged sample size is 8100; recruitment will be in three data cycles with brief intervals allowing for descriptive interim analyses. Those patients reacting positively to any of the study allergens will be followed-up specifically to identify the source of sensitizing and/or eliciting exposure(s). Results will inform risk reassessment and subsequent risk management measures. Study results will be published in an open-access peer-reviewed scientific journal. Structured post-marketing surveillance of consumer risk of contact allergy by monitoring prevalences of positive patch test reactions in a dedicated European expert network is developed which can serve as a model for further chemicals. Important outcomes will be either a confirmation of effectiveness of risk management measures in place, or alternatively identifying aspects needing improvement (for certain cosmetic product categories). DRKS registration (DRKS00033263) 16.09.2024, mirrored at https://trialsearch.who.int.