Effect of chlorination on the estrogenic/antiestrogenic activities of biologically treated wastewater.

Chlorination is widely used in wastewater reclamation, however harmful disinfection byproducts (DBPs) may be formed during disinfection. These DBPs are considered as a potential and important source of endocrine-disruption. In this study, the effects of chlorination on estrogenic and antiestrogenic activities in biologically treated wastewater were evaluated by yeast two-hybrid assay. For the first time, chlorination was found to increase the antiestrogenic activity of wastewater notably and decrease the estrogenic activity. By fractionating dissolved organic matter (DOM) in wastewater into different fractions, it was found that the polar compounds (PC) fraction of DOM was the key fraction involved in increasing antiestrogenic activity during chlorination of wastewater. Furthermore, fluorescence spectroscopy analysis on different fractions of soluble organic compounds in wastewater suggested that the PC fraction contained most of the aromatic amino acids and humic/fulvic acid, which were then demonstrated as the precursors of antiestrogenic DBPs through chlorination experiments of tryptophan, humic acid, and tannic acid.