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

Abstract

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 highthroughput 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,8Hperfluorooctane-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.

Per- and Polyfluoroalkyl Substances (PFAS) Mixture during Pregnancy and Postpartum Weight Retention in the New Hampshire Birth Cohort Study (NHBCS)

“…Liu et al found that PFOS could increase mRNA expression of PPARγ, CCAAT/enhancer-binding protein-α (C/EBPα), lipoprotein lipase, and leptin [ 37 ]. Furthermore, animal and in vitro studies have shown that certain PFAS, including PFOA and PFOS, have estrogenic activity and directly interact with estrogen receptors (ERs) [ 38 , 39 , 40 , 41 , 42 , 43 ]. ERs play an important part in energy balance, glucose homeostasis, and lipid metabolism [ 44 , 45 ].…”

PFAS Modulate Osmotic Signaling Independent of Gravimetric Changes in the Rat Uterus

“…Per- and polyfluoroalkyl substances (PFAS) are a large class of fluorinated organic chemicals that are ubiquitous and persistent in humans and the environment and are thus of interest to regulatory agencies and the general public. Multiple PFAS have been identified as potential endocrine-disrupting chemicals [ 1 ] due to estrogen receptor activation [ 2 , 3 , 4 ], impacts on puberty timing [ 5 , 6 , 7 , 8 ]. In this study, the uterotrophic assay was used to address the impact of PFAS as a mammalian endocrine disruptor.…”

“…Previous work in other labs identified PFAS with estrogenic activation in fish or estrogen receptor activation with in vitro screens. Villeneuve et al [ 7 ] used tiered testing, starting with in vitro estrogen receptor screening and further testing in fish for the estrogen sensitive endpoint of vitellogenin activation. Of the 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 were positive estrogen receptor activators in vitro, only three induced vitellogenin activation (FC8-diol, FC10-diol, and FC8-DOD) [ 7 ].…”

“…Villeneuve et al [ 7 ] used tiered testing, starting with in vitro estrogen receptor screening and further testing in fish for the estrogen sensitive endpoint of vitellogenin activation. Of the 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 were positive estrogen receptor activators in vitro, only three induced vitellogenin activation (FC8-diol, FC10-diol, and FC8-DOD) [ 7 ]. Evans et al [ 2 ] reported in vitro human estrogen receptor activation with four PFAS (PFHxS, 8:2 FTOH, 6:2 FTOH, and PFOSA) from the sixteen PFAS tested.…”

“…This work was conducted to assess the potential in vivo estrogenic activity of various PFAS in a mammalian model. Some of the PFAS tested herein induced transcriptional activation of estrogen receptor with the in vitro assays [ 2 ] or induced vitellogenin activation in fish [ 7 , 9 ]. Tiered testing beginning with in vitro screening and building out to the in vivo uterotrophic model allows for a multiple-level approach to investigate the hormonal activity of these PFAS.…”