While much research and legislation has focused on quantification of specific disinfection by-products, novel bioanalytical assays can provide an effect-based approach to complement chemical analysis when assessing water quality. Bioanalytical assays are ability to detect the toxicity of unknown mixtures and provide information regarding all bioactive components, including disinfection by-products (DBPs). Of interest to human health are DBPs that can damage or compromise genetic material, since this mechanism of DBP action addresses the potential risks of carcinogenicity, reproduction and fertility. The genotoxicity test is a bioassay that may be used to evaluate the ability of a water sample to damage cellular DNA.  In this study, interdependent relationships between natural organic matter (NOM) and DBP precursor removal were examined with respect to the genotoxic potential of drinking water. Coagulation optimization was performed to achieve a reduction in DBP formation and genotoxic potential for several drinking water sources in Ontario, Canada. The approach was also applied to evaluate performance associated with individual treatment processes.  The formation of total trihalomethanes (TTHM) and haloacetic acids (HAAs), as well as total organic halides was monitored. In addition, 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (also known as MX) was measured. MX represents an emerging DBP that accounts for a large fraction of the total mutagenicity observed in drinking water. DBP concentrations were correlated to overall genotoxicity in order to identify their contribution to a given toxic response, using the SOS-Chromo-TestTM.  None of the raw waters tested exhibited a genotoxic response prior to chlorination, however post-chlorination at bench-scale, genotoxicity increased as a function of NOM concentration and DBP formation. River waters with TOC values ranging from 5.0 to 6.0 mg/L exhibited the highest genotoxicity values. Most notably, MX formation was strongly correlated with genotoxic response, whereas TTHM and HAA9 exhibited no influence on overall toxicity.

Genotoxic potential of disinfection by-products

248th National Meeting (2014)

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