Integrated in silico and in vitro assessment of estrogen and androgen receptor activity of 10 selected PFAS within an Integrated Approach to Testing and Assessment (IATA)

Abstract

The potential of per- and polyfluoroalkyl substances (PFAS) to disrupt endocrine systems continues to be a regulatory concern. However, effectively prioritizing these structurally diverse chemicals remains challenging due to inconsistencies in predictive and experimental data. In this study, we employed a multi-tiered evaluation strategy that combines in silico modeling, in vitro assays, and curated mechanistic data within the OECD's Integrated Approach to Testing and Assessment (IATA) framework. Molecular docking using AutoDock Vina, CB-Dock2, and Endocrine Disruptome consistently revealed strong binding affinities of long-chain PFAS, particularly PFDA, PFOA, and 10:2 FTOH, to estrogen and androgen receptors. These predictions were corroborated by ER and AR transactivation assays (OECD TG 455/458), which demonstrated ER agonist and AR antagonist activity for the same compounds. In contrast, short-chain and sulfonated PFAS (PFHxA, PFBS, PFOS) exhibited limited to no activity across platforms. To enhance the biological relevance of the prioritization, we compiled supporting mechanistic evidence by applying the IATA framework to organize data along the adverse outcome pathway from molecular initiating events, through key events, to predicted adverse outcomes. Literature-reported alterations in steroidogenic enzymes and hormone levels were included to enrich mechanistic depth. All lines of evidences were systematically integrated into a weight-of-evidence matrix, enabling a transparent and biologically plausible ranking of PFAS based on receptor interaction, functional activity, and endocrine-disruptive potential. This combined approach identified PFDA and PFOA as high-priority endocrine disruptors and offers a scalable, non-in vivo strategy for the screening and risk-based prioritization of environmentally persistent chemicals.