2-Mercaptobenzothiazole-derived vulcanization accelerators in urine samples from Chinese adults.

Studies have discovered wide presence of 2-mercaptobenzothiazole (2-MBT) and 2-MBT-derived vulcanization accelerators (MVAs) in household dust samples, suggesting that these chemicals may have been pervasive in the environment. However, despite the potential for human exposure, the presence of MVAs in human urine, a common matrix used for assessing exposure to environmental chemicals, has not been thoroughly investigated. The current study comprehensively analyzed 11 kinds of MVAs in urine samples from the recruited general population (n = 197) living in Taizhou city, China. Five kinds of MVAs were detectable in >50 % of human urine samples. This indicates the widespread exposure to these vulcanization accelerators among the general population. The predominant target analytes in human urine were 2-MBT and 2,2'-dithiobisbenzothiazole (MBTS), with the mean urinary concentrations of 2.7 ng/mL (range <limits of detection (LOD)-22 ng/mL) and 1.2 ng/mL (<LOD-15 ng/mL), respectively. 2-MBT and N-cyclohexyl-2-benzothiazolamine had significantly higher (p < 0.05) mean urinary levels in male participants than that in female participants. Levels of 2-MBT and MBTS in human urine across different age categories demonstrated a notably significant (p < 0.01) inverse correlation with human age. The estimated highest mean daily exposure value was observed for 2-MBT (76 ng/kg bw/day), which was followed by MBTS (34 ng/kg bw/day) and 2-(methylthio)benzothiazole (27 ng/kg bw/day). This study comprehensively characterizes the occurrence of multiple MVAs in human urine. These data are crucial for advancing our understanding of human exposure to these emerging vulcanization accelerators.