Summary Background The prevalence of contact allergy in the general population is nearly 20%.
Objectives This study aimed to monitor the development of contact allergy to allergens from the TRUE-test (panels 1 and 2) between 1990 and 2006.
Methods Two random samples of adults from the general population in Copenhagen, Denmark, were invited to participate in a general health examination including patch testing. In 1990 and 2006, we patch tested and questioned 543 and 3460 adult Danes. Patch test readings were performed on day 2 only.
Results The overall prevalence decreased significantly from 15·5% in 1990 to 10·0% in 2006, mainly as a result of a decrease in thimerosal allergy from 3·4% to 0·8%. Furthermore, the prevalence of cobalt allergy and rubber-related allergens decreased from 1·1% to 0·2% and from 1·5% to 0·2%, respectively. Stratification by sex and age group revealed decreasing prevalences of contact allergy in all male age groups and in young and middle-aged female age groups (18–55 years) whereas increasing prevalences were observed among older women (56–69 years). The diverging trend observed in women was probably explained by a cohort effect due to a change in the prevalence of nickel allergy following the Danish regulation on nickel exposure.
Conclusions Although the overall prevalence of contact allergy decreased in the general population, frequent contact allergens such as fragrance mix II and methyldibromo glutaronitrile were not tested. Thus, contact allergy remains prevalent in the general population.