Human urinary occurrence of dithiocarbamate vulcanization accelerators and their exposure estimation

Dithiocarbamate vulcanization accelerators (DVAs) are widely used in rubber manufacturing, yet their potential human exposure and associated health risks remain poorly understood. Previous studies have identified DVAs in various environmental matrices, such as dust and sediments, but their occurrence in human biological samples has not been investigated. This study aims to fill this critical research gap by conducting the first comprehensive biomonitoring assessment of DVAs in human urine, providing direct evidence of human exposure. A total of 263 urine samples were collected from Chinese adults and analyzed for eight DVAs. Seven out of eight target compounds were detected, with detection frequencies ranging from 14 % to 94 %. Zinc diethyldithiocarbamate (ZDEC) was the predominant compound, with a mean concentration of 1.6 ng/mL (range: <LOD–12 ng/mL). Notably, males exhibited significantly higher urinary levels of ZDEC (1.7 ± 0.28 ng/mL vs. 1.3 ± 0.33 ng/mL; p = 0.021) and zinc dibutyldithiocarbamate (ZDBC; 0.78 ± 0.18 ng/mL vs. 0.50 ± 0.10 ng/mL; p = 0.017) compared to females, while urinary concentrations of ZDEC and zinc dibenzyldithiocarbamate (ZBEC) were inversely correlated with age. Daily exposure (DE) estimation revealed that ZDEC had the highest mean DE value at 48 ng/kg bw/day, followed by ZEPC (29 ng/kg bw/day) and ZDBC (21 ng/kg bw/day). These findings provide essential insights into human exposure patterns to DVAs, offering a scientific basis for future risk assessment and regulatory considerations. Given the widespread detection of these compounds and their potential toxicity, further research is warranted to elucidate their health implications and major exposure pathways.