Estrogenic effects of fluorinated diiodine alkanes in MCF-7 cells, H295R cells and zebrafish embryo assays

Verification of In Vivo Estrogenic Activity for Four Per- and Polyfluoroalkyl Substances (PFAS) Identified as Estrogen Receptor Agonists via New Approach Methodologies

Given concerns about potential toxicological hazards of the thousands of data-poor per- and polyfluorinated alkyl substances (PFAS) currently in commerce and detected in the environment, tiered testing strategies that employ high-throughput in vitro screening as an initial testing tier have been implemented. The present study evaluated the effectiveness of previous in vitro screening for identifying PFAS capable, or incapable, of inducing estrogenic responses in fish exposed in vivo. Fathead minnows (Pimephales promelas) were exposed for 96 h to five PFAS (perfluorooctanoic acid [PFOA]; 1H,1H,8H,8H-perfluorooctane-1,8-diol [FC8-diol]; 1H,1H,10H,10H-perfluorodecane-1,10-diol [FC10-diol]; 1H,1H,8H,8H-perfluoro-3,6-dioxaoctane-1,8-diol [FC8-DOD]; and perfluoro-2-methyl-3-oxahexanoic acid [HFPO-DA]) that showed varying levels of in vitro estrogenic potency. In agreement with in vitro screening results, exposure to FC8-diol, FC10-diol, and FC8-DOD caused concentration-dependent increases in the expression of transcript coding for vitellogenin and estrogen receptor alpha and reduced expression of insulin-like growth factor and apolipoprotein eb. Once differences in bioconcentration were accounted for, the rank order of potency in vivo matched that determined in vitro. These results provide a screening level benchmark for worst-case estimates of potential estrogenic hazards of PFAS and a basis for identifying structurally similar PFAS to scrutinize for putative estrogenic activity.

Fluorinated diiodine alkanes exert developmental toxicity on embryo-larval stages of zebrafish strain AB via regulating the expression of the specific endocrine-related genes

Fluorinated diiodine alkanes (FDIAs) are environmental pollutants, including octafluoro-1,4-diiodobutane (PFBDI), hexadecafluoro-1,8-diiodooctane (PFODI) and dodecafluoro-1,6-diiodohexane (PFHxDI). They showed an estrogenic effect in in vitro studies. However, little information is currently available regarding the toxicity of FDIAs in in vivo studies. Zebrafish (Danio rerio) is a vertebrate animal model that is increasingly used for toxicity and efficacy screening as well as for assessing the toxicity and safety of novel compounds, pollutants and pharmaceuticals. In the present study, we investigated the developmental toxicity of FDIAs (PFBDI, PFHxDI and PFODI) and the specific endocrine-related gene expression in zebrafish embryos. The results revealed that all three FDIAs showed developmental toxicity on zebrafish embryos. The half-maximal effective concentration values for PFBDI, PFHxDI and PFODI were 0.89 ± 0.07, 0.53 ± 0.04 and 0.04 ± 0.007 mm, respectively. PFHxDI exhibited the highest developmental toxicity compared with the other FDIAs. In addition, all three FDIAs significantly upregulated the expression of estrogen receptor (esr)1 and cytochrome P450 (CYP) 19b (CYP19b), but did not significantly affect the expression of esr2b, CYP17 and CYP19a in zebrafish. The upregulation effect of PFHxDI was greater than the effect of PFBDI and PFODI. This study furthers our knowledge on the effects of FDIAs on the developmental toxicity and the specific endocrine-related gene expression in the embryo-larval stages of zebrafish. Our results provided a preliminary insight into the toxicity of FDIAs in zebrafish, which will be of great relevance regarding future studies on FDIAs in the environment.