Trends in formaldehyde and formaldehyde-releaser contact allergies as compared with market exposure in Thailand

Background: Formaldehyde and formaldehyde releasers (FRs) are common preservatives in cosmetics and household products. Their contact allergy trends are decreasing in Europe and America, but trend data for Asia are limited. Objectives: The first objective was to determine the prevalences of and trends in contact allergies to formaldehyde and FRs. The second objective was to establish how often formaldehyde and FRs were mentioned on the labels of products sold in the Thai market. Methods: Twenty years of data on patch test results for formaldehyde and FRs were reviewed. Their frequency of mention on the labels of 5855 products was analysed. Results: The trends in contact allergy to formaldehyde and FRs were decreasing. The overall prevalence of formaldehyde contact allergy was 2.5%. The most common FR to cause contact allergy was quaternium-15. Formaldehyde and FRs were identified as ingredients in 10.2% of the products surveyed. Dimethylol dimethyl hydantoin was the most common FR (5.2%). The highest use of formaldehyde and FRs (15.5%) was in hair care products. Conclusion: Although contact allergy trends in Thailand were decreasing, the proportion of products with FRs remained high. Comprehensive and universal legislation is needed to control the presence of formaldehyde and FRs.