Identification of priority organophosphate esters and priority control areas based on toxic effects in the Taihu Basin, China

Organophosphate esters (OPEs) have been frequently detected in the Taihu Basin. Surface water contains mixtures of OPEs, which can cause adverse toxic risk to the ecological environment. However, the priority OPEs and priority control areas in the Taihu Basin were unclear, hindering effective management. Therefore, a survey of 79 surface water sampling sites in the Taihu Basin, including 15 major inflow river entrances, sections along the Wangyu River and Taipu River, and 8 rivers in the Xinmeng River area, was conducted. Priority OPEs and areas were identified by correlating OPE exposure concentrations with their toxic effects in surface waters of the basin. In vitro toxicity tests on 13 individual OPEs showed that 7 of them exhibited DNA-damaging effects, with TCIPP demonstrating the strongest activity. However, none of the 13 OPEs induced significant estrogenic disrupting effects. Genotoxic and estrogenic endocrine-disrupting effects in surface water extracts were observed. Halogenated OPEs and aryl OPEs showed a high correlation with the distribution of genotoxicity in surface water, whereas all OPEs showed a weak correlation with estrogenic disrupting effects. Halogenated OPEs were detected in concentrations up to 182.40 ng/L in the northwestern lake entrances, with tris (2-chloroisopropyl) phosphate (TCIPP) (up to 89.10 ng/L) and tris (2-chloroethyl) phosphate (TCEP) (up to 145.90 ng/L) as the main components, while aryl OPEs were detected at low frequencies and concentrations in the Taihu Basin. The genotoxicity ranking of OPEs in the basin was: TCIPP > TCEP > TMPP (tri-m-cresyl phosphate) > TPHP (triphenyl phosphate) > TDCIPP (tris (1,3-dichloro-2-propyl) phosphate) > TDBPP (tris (2,3-dibromopropyl) phosphate) > EHDPP (2-ethylhexyl diphenyl phosphate), with TCIPP identified as the priority OPE. The entrances in northwestern Taihu Lake exhibited the most prominent genotoxic risks from OPEs, making them the priority control areas across the Taihu Basin. The "priority substance identification combined with priority area screening" approach based on toxicity effect risk assessment provides a scientific basis for reducing ecological risks in the Taihu Basin.