The Epidemiology of Fragrance Allergy: Questions and Needs

Background: There are still open questions about the safety of fragrances. Objectives: To evaluate the evidence concerning the frequency of contact dermatitis to fragrances in the general population and selected subgroups and the risk factors for sensitization and clinical manifestations. Methods: Review of published data. Results: No criteria for a reliable diagnosis of ‘contact dermatitis’ are available. International recommendations and standardization for patch test methods exist; however, the question whether agents that are positive are causally linked to contact dermatitis remain fraught with uncertainties concerning false-positive rates and clinical relevance. Most of the discussion concerning prevalence or incidence variations of allergic contact dermatitis to fragrances concentrate on the frequency of positive patch tests in clinical series, i.e. ‘floating numerators’. Conclusions: Risk assessment requires that data from different sources are integrated and compared. Both a ‘sentinel surveillance’ system and more refined epidemiological studies in well-defined populations are needed to reliably assess the risks associated with fragrance exposure.