In vitro-in silico-based probabilistic risk assessment of combined exposure to bisphenol A and its analogues by integrating ToxCast high-throughput in vitro assays with in vitro to in vivo extrapolation (IVIVE) via physiologically based pharmacokinetic (PBPK) modeling

[Display omitted] •An in vitro- and in silico-based integrated risk assessment approach is described.•This approach is used to derive human equivalent doses for BPA, BPS, BPF, and BPAF.•Combined risks of BPA and its analogues for different populations are assessed.•Combined risks for toddlers and adults with high dietary exposure may be of concern.•This study shows it is feasible to use in vitro assays for human health risk assessment. Combined risk assessment of endocrine effects of bisphenol A (BPA) and its analogues, such as bisphenols S, F, and AF (BPS, BPF, and BPAF), is challenging due to lack of related common toxicity metrics. This study conducted a population-based in vitro-to-in vivo extrapolation using physiologically based pharmacokinetic (PBPK) models coupled with Monte Carlo simulations to convert ToxCast in vitro estrogen receptor (ER) assays to human equivalent doses (HEDs). The ER pathway-based HEDs were compared with HEDs from animal studies and used to assess the combined risks for different populations across different countries/regions in a probabilistic manner. The estimated ER pathway-based HEDs for the four bisphenols (BPs) matched the animal-derived HEDs. The HEDs for the ER gene transcription (the common biological process target among BPs) were 0.40 (2.5th–97.5th percentiles: 0.06–5.42), 4.43 (0.69–53.84), 3.30 (0.51–626.57), and 1.12 (0.16–9.73) mg/kg/day for BPA, BPS, BPF, and BPAF, respectively. Results suggest a potentially moderate concern for combined risks of activating the ER pathway for toddlers and adults with high dietary exposures. This study presents in vitro-based credible HEDs for the four BPs and represents an advancement in the application of in vitro–in silico-based alternative approaches in human health risk assessment.