Temporal changes in chromium allergy in Denmark between 2002 and 2017

Background In 2012, Danish authorities submitted a proposal to the European Chemical Agency restricting the content of hexavalent chromium to a maximum of 3 ppm in leather goods. Following its adoption, this proposal was implemented in 2015 as a directive in the EU. Objectives To examine the temporal trend of chromium contact allergy in adult dermatitis patients patch tested between 2002 and 2017, and to determine clinical characteristics and causative exposures in these patients. Methods All adult dermatitis patients patch tested between 2002 and 2017 were included. Patch test data were reviewed retrospectively. Comparisons were performed with the χ 2 test and logistic regression analysis. Results A total of 13 379 adults aged 18 to 99 years were patch tested between 2002 and 2017. The overall prevalence of chromium allergy was 2.2%. An overall decreasing trend was found for the prevalence of chromium allergy (Ptrend = 0.00002). Specifically, a significant difference was found for the study periods 2010 to 2013 (Ptrend = 0.002) and 2014 to 2017 (Ptrend < 0.0001) as compared with 2002 to 2005. Leather remained the most important single cause of allergic contact dermatitis caused by chromium. The proportion of clinically relevant leather exposures increased from 42.3% during 2002 to 2009 to 54.8% during 2010 to 2017 (P = 0.04). Conclusions The prevalence of chromium allergy is decreasing. The EU Directive restricting the use of hexavalent chromium in leather goods is thought to be playing a central role in this change.