Prenatal exposure to xanthate vulcanization accelerators: Transplacental transfer efficiency and fetal growth effects

Xanthate vulcanization accelerators (XVAs) are widely used in the synthetic rubber industry and have been frequently detected in environmental matrices and human urine. However, their occurrence in human blood and potential transplacental transfer remain unexplored. In this study, we measured eight XVAs in paired maternal and cord serum samples from 150 pregnant women in China. KHX (potassium hexylxanthate; mean 3.30 ng/mL), KAX (potassium amylxanthate; 3.40 ng/mL), and KPX (potassium propylxanthate; 3.66 ng/mL) were the major XVAs in maternal serum. KAX (mean 3.42 ng/mL) was the major XVA in cord serum, followed by KPX (2.68 ng/mL) and KHX (2.48 ng/mL). Calculated mean transplacental transfer efficiencies (TTEs) of the different XVAs ranged from 0.52 (KHX) to 1.02 (potassium ethylxanthogenate). A significantly negative correlation (p < 0.01) was found between the TTEs of XVAs and their log K_ow values. In addition, significantly negative associations (p < 0.05) were observed between cord serum concentrations of certain XVAs (e.g., KHX, KAX, KPX, and potassium butylxanthate) and fetal growth parameters, including femur length and head circumference. These findings provide the first evidence of transplacental transfer behaviors of XVAs, and suggest a potential association between prenatal XVA exposure and impaired fetal growth.