Contact allergy to biocides is common throughout Europe, and regional differences could be explained by differences in exposure or characteristics of the population tested. Timely regulatory action for isothiazolinones is required. Although MDBGN is banned from cosmetics products since 2005, sensitization prevalence has not appeared to plateau. IPBC is an emerging allergen with an increasing prevalence over the last few years, and its inclusion in the European baseline series may be appropriate.