Biomonitoring of chlorinated polyfluoroalkyl ether sulfonic acid in the general population in central and eastern China: Occurrence and associations with age/sex.

Although chlorinated polyfluoroalkyl ether sulfonic acid (Cl-PFESA) has been reported to be widespread in different environmental matrices of China, its exposure data in the general Chinese population are very limited. In the present study, the serum-to-whole-blood ratio was first assessed for 6:2 Cl-PFESA (mean/median: 2.07/1.82) based on its paired concentrations (n = 36), which allows a comparison in different blood matrices. The exposure levels of Cl-PFESAs in the general population were investigated by collecting blood samples (n = 1516) from residents of seven cities in central and eastern China. 6:2 Cl-PFESA was observed as the third-highest contributing polyfluoroalkyl substance (PFAS) (8.69%), with the median concentration at 2.18 ng/mL, indicating its importance for assessing the human exposure risks of PFASs. The regional difference between 6:2 Cl-PFESA and perfluorooctane sulfonate (PFOS) can be explained by their use pattern in China. Overall, similar to PFOS, 6:2 Cl-PFESA displays significantly increasing levels with increasing age for both males and females, with significantly higher levels in males. However, a significant sex dependence was found for 6:2 Cl-PFESA in one specific age group (41-60), while there was no significance in the other groups although males display higher levels than females. Our study provides robust data regarding human exposure to 6:2 Cl-PFESA in the general population in central and eastern China.