From bisphenol A to its analogues: Shifts in occurrence and risk in wastewater treatment plants

Restrictions on bisphenol A (BPA) have accelerated the substitution by bisphenol analogues (BPs), yet the analysis of shifts in risk contribution of BPs in wastewater systems, as well as a time-series substitution effect validation for BPs in global wastewater, remains lacking. To address this knowledge gap, we investigated 10 BPs in four municipal wastewater treatment plants (WWTPs) in South China, complemented by a global analysis of 70 relevant studies. The results showed that nine BPs were detected in influents (2.1-1850 ng L^-1), with BPA, BPS, and BPF as the dominant analogues. Seven BPs were detected in effluents (1.8-179 ng L^-1). While conventional treatment processes efficiently removed high-abundance BPs, removal rates of several low-level analogues were low or even negative (down to -54.8%). These BPs might not be truly removed, but were probably converted from their conjugates or released from particles during treatment. Notably, a significant transition in risk profiles was observed. Although BPA dominated estrogenic activity and ecological risk in influents, BPs contributed up to 60.9% of the total estrogenic equivalents and 88.8% of the total risk quotient in effluents. Global data synthesis confirmed that bisphenol pollution has shifted from BPA-centered to BPs-diversified patterns, largely driven by regional regulatory restrictions and inefficient removal of BPs in WWTPs. These findings indicate that BPA regulation may unintentionally drive the environmental persistence of alternative compounds in aquatic ecosystems with comparable persistence and risk. The present study demonstrates a transition from BPA dominance to analogue-driven risk, and emphasizes the need for further continuous monitoring and comprehensive ecological assessment targeting emerging BPs.