The environmental occurrence, fate, and risks of 25 endocrine disruptors in Slovenian waters.

Natural hormones, synthetic steroids and bisphenols are among the most active endocrine disruptors (EDs) in the aquatic environment, with great potential for causing adverse effects in aquatic organisms and humans. In this study, a focused group of 25 potent estrogenic and other ED compounds were simultaneously measured in wastewaters (WWs) and receiving surface waters (SWs) before and after wastewater treatment plants (WWTPs), where their removal efficiency was also estimated. Up to 16 of 25 EDs were successfully quantified in SWs and WWs, with bisphenols BPS, BPA, and BPF together with estriol and chlormadinone being the most prevalent with the highest measured concentrations of up to 35 μg/L in WWs and 400 ng/L in SWs. High load and insufficient removal of these substances by WWTPs lead to a significant increase in their concentrations in the receiving SWs downstream, while other sources could be responsible for an important portion of river contamination with EDs. Removal efficiency was very good for most EDs, although only from 0 to 44 % for E2, which shows a need for the improvement of current removal techniques. E2 and EE2 contribute the most to the alarmingly high risks of the total ED estrogenic potential, with the value increased by 36 % in SWs downstream from WWTPs, and the RQ value for the total estrogenic potential in individual SW samples being three orders of magnitude higher than that representing high risk. An additional comprehensive multi-parameter risk assessment determined high risk quotient and priority index values for BPA, E2, BPS and E1 with values of up to 450 in SWs. Our results show a focused insight into the risks associated with an important group of EDs and the role of WWTPs, while further highlighting the importance of regular monitoring of the environmental occurrence and risks of a focused range of EDs.