The methylisothiazolinone and methylchloroisothiazolinone metabolite N-methylmalonamic acid (NMMA) in urine of children and adolescents in Germany - Human biomonitoring results of the German Environmental Survey 2014-2017 (GerES V).

Mixtures of methylisothiazolinone and methylchloroisothiazolinone are used as biocides in cosmetics, cleaning agents, and water-based paint. A biomonitoring method to evaluate exposure to these compounds was developed using N-methylmalonamic acid (NMMA), the main metabolite of both, methylisothiazolinone and methylchloroisothiazolinone, as the exposure biomarker. First-morning void urine samples (N = 2078) of 3- to 17-year-old children and adolescents living in Germany were analysed for concentrations of NMMA in the population representative German Environmental Survey for Children and Adolescents GerES V (2014-2017). NMMA was quantified in almost all samples, with a geometric mean concentration of 6.245 μg/L (5.303 μg/g) and a 95th percentile of 15.0 μg/L (12.6 μg/g). Urinary concentrations could not be related to self-reported application of specific cleaning agents or personal care products, leaving potential, specific sources of exposure unrevealed as most products relevant for isothiazolinone exposure are used ubiquitously. For the first time, reference values can be derived for urinary NMMA for children and adolescents in Germany, facilitating a more substantiated exposure assessment.