Behaviour and Health Risk Assessment of Endocrine Disrupting Chemicals from Wastewater

Abstract

Water supply has become a social and economic issue in many countries as a result of global climate change, fast population growth, industrial and urban development. To address this issue, water recycling has been considered as a feasible technology to supplement the existing water supply. However, a major challenge with water recycling is the removal of harmful contaminants to meet drinking water guidelines and industrial requirements. Although various technologies can remove most contaminants efficiently, recent studies have shown that many endocrine disrupting chemicals (EDCs) can cause adverse health effects on wildlife species and humans at extremely low level.

EDCs from wastewater treatment effluent are the major point source entering the aquatic environment. Consequently, various adverse health effects have been observed in wildlife species, such as population changes, reproductive abnormalities, imbalanced sex ratios and behaviour changes. Many adverse human health effects such as prostate cancer, breast cancer and birth defects have also been implicated with the exposure to EDCs. Thus, it is important to study these environmental contaminants. The main aim of this work was to develop an understanding of the behaviour and health risks of EDCs from wastewater. This work focused on four estrogens, estrone (E1), 17β-estradiol (E2), estriol (E3), and 17α-ethinylestradiol (EE2) and three phenolic compounds, nonylphenol (NP), octylphenol (OP) and bisphenol A (BPA).

The behaviour of a chemical in the environment is largely dependent on its physicochemical properties such as aqueous solubility (S) and octanol-water partition coefficient (Kow). Physicochemical properties, however, are related to chemical structures. A quantitative structure-property relationship (QSPR) evaluation was conducted by using measured physicochemical properties and calculated molecular descriptors. With single and multiple linear regression methods, good linear relationships were found between the measured log Kow values and three molecular descriptors: log FOSA (hydrophobic component of the total solvent accessible surface area), log FISA (hydrophilic component of the total solvent accessible surface area) and log PSA (Van de Waals surface area of polar nitrogen and oxygen atoms). Similar but weaker correlations were found between the measured log S values and each of the three molecular descriptors. The relationships can be used to obtain property values for various steroidal EDCs which may have potential environmental effects.