Chlorinated Polyfluoroalkylether Sulfonic Acids Exhibit Stronger Estrogenic Effects than Perfluorooctane Sulfonate by Activating Nuclear Estrogen Receptor Pathways

Chlorinated polyfluoroalkylether sulfonic acids (CI-PFESAs) have been shown to have potential thyroid hormone (TH) disruption effects. Here, we further investigated their estrogenic effects and underlying mechanisms. In vivo results revealed that exposure of zebrafish to CI-PFESAs induced disorder of sex hormones during the early embryonic stages and caused histopathological lesions in the gonads of adult zebrafish relative to control groups. To find out whether the estrogen receptor is the molecular target of CI-PFESAs, the binding interaction between CI-PFESAs and ERs was investigated using a series of in vitro assays. We found that all tested chemicals could bind directly to ERs and exhibit relatively weak agonistic activity toward ERs, suggesting that the ER-mediated signaling pathway is directly involved in the estrogenic effects of CI-PFESAs. The internal dose of 8:2 CI-PFESA was significantly higher than the others, which explained why it obviously displayed an ER agonistic effect despite its weak ER binding affinity. Taken together, these results uncover that, in addition to the TH disruption effect, CI-PFESAs might also cause estrogenic effects by activating ER pathways.