The endocrine disrupting activity of surface waters and of wastewater treatment plant effluents in relation to chlorination.

The present study investigated the biological quantification of estrogenic activity in the effluent of a wastewater treatment plant (WWTP) and in the recipient river in north-western Italy. Samples of the WWTP effluent and those of river water upstream and downstream the WWTP were taken from September 2006 to May 2007. The effluent was evaluated in the presence and absence of chlorination. The E-screen assay, with human estrogens receptor-positive MCF-7 BUS breast cancer cells, was performed on samples after solid-phase extraction to determine the total estrogenic activity by measuring the 17beta-estradiol equivalent quantity (EEQ). In order to study the correlation between estrogenicity and toxicity, untreated samples were also assayed with the acute toxicity test Microtox. Furthermore, to determine the efficiency of the chlorination process, all the samples were analysed for disinfection by-products (trihalomethanes) and Escherichia coli. The mean EEQs were 5.0 ng/L (+/-6.1 ng/L) upstream of the plant, 6.7 ng/L (+/-7.4 ng/L) downstream from the plant and 23.3 ng/L (+/-20.4 ng/L) in the WWTP effluent. The difference between upstream and downstream of the treatment plant was not significant. Chlorinated water samples had lower estrogenic activity and E. coli concentrations, but had greater toxicity and higher trihalomethane concentrations. Estrogenic activity was not correlated with toxicity. These results suggest that the WWTP effluent had little impact on the estrogenic activity of the recipient river.