Co-exposure profiles of PAHs and their derivatives in coking plant workers' serum and associations with liver function.

Coking plant workers are at great exposure risk to polycyclic aromatic hydrocarbons (PAHs) and their derivatives, with mounting evidence indicating PAH exposure being associated with liver impairment. However, impacts of co-exposure to PAHs and their derivatives on liver function remain poorly understood. Herein, serum samples were collected from coking plant workers, nearby population, and control population to study 10 PAHs, 7 methylated-PAHs (MPAHs), 17 heterocyclic PAHs (HPAHs), and 1 oxygenated-PAH (9-fluorenone). Furthermore, association between them and liver function biomarkers was explored based on quantile g-computation, weighted quantile sum regression, and Bayesian kernel machine regression models. Median levels of PAHs, MPAHs, HPAHs, and 9-fluorenone in the serum of coking plant workers were 2230, 738, 1250, and 18.8 ng/g lipid, respectively, which were significantly higher than those in other two groups. Coking process workers had higher exposure levels to PAHs and their derivatives than those in other processes. Further, results revealed positive joint effect of PAHs and their derivatives with liver function biomarkers, including total bilirubin (TBIL), indirect bilirubin (IBIL), direct bilirubin, alanine aminotransferase, and aspartate aminotransferase (AST). Notably, PAHs and their derivatives were significantly positively correlated with IBIL, TBIL and AST, with 4-methyldibenzofuran, dibenzofuran, phenanthrene, 5,6-benzoquinoline, quinoline, and indole as primary contributor. PAH derivatives had more significant effect on liver function biomarkers from a co-exposure perspective, although their concentrations were much lower than those of parent PAHs. This study emphasizes significance of PAH derivatives and contributes to better understanding the underlying mechanisms of PAH and their derivative exposure on liver function impairment.