Eco-toxicity and human estrogenic exposure risks from •OH-initiated photochemical transformation of four phthalates in water: A computational study

Transformation products (TPs) of emerging organic contaminates (EOC5) in water are still rarely considered in environmental risk assessment, although some have been found to be concern. (OH)-O-center dot is believed as an important reactive species both in indirect phototransformation and advanced oxidation technology. Thus, eco-toxicity and human estrogenic exposure risks of four phthalates and TPs during the (OH)-O-center dot-initiated photochemical process were investigated using computational approach. Four phthalates can be degraded through (OH)-O-center dot-addition and H-transfer pathways. The (OH)-O-center dot-addition TPs were predominant for dimethyl phthalates, while H-transfer TPs were predominant for other three phthalates. Compared with phthalates, (OH)-O-center dot-addition TPs (o-OH-phthalates) were one level more toxic to aquatic organisms, and m-OH-phthalates exhibit higher estrogenic activity. Although H-transfer TPs were less harmful than (OH)-O-center dot-addition TPs, some of them still have aquatic toxicity and estrogenic activity. Therefore, more attentions should be paid to photochemical TPs and original EOC5, particularly those exhibiting high estrogenic activity to humans. (C) 2015 Elsevier Ltd. All rights reserved.