Date Published: January 26, 2017
Publisher: Public Library of Science
Author(s): Ying Guan, Xiaodong Wang, Minghung Wong, Guoping Sun, Taicheng An, Jun Guo, Guoxia Zhang, Yiguo Hong.
An increasing number of industrial, agricultural and commercial chemicals in the aquatic environment lead to various deleterious effects on organisms, which is becoming a serious global health concern. In this study, the Ames test and SOS/umu test were conducted to investigate the potential genotoxicity and mutagenicity caused by organic extracts from drinking water sources. Organic content of source water was extracted with XAD-2 resin column and organic solvents. Four doses of the extract equivalent to 0.25, 0.5, 1 and 2L of source water were tested for toxicity. All the water samples were collected from six different locations in Guangdong province. The results of the Ames test and SOS/umu test showed that all the organic extracts from the water samples could induce different levels of DNA damage and mutagenic potentials at the dose of 2 L in the absence of S9 mix, which demonstrated the existence of genotoxicity and mutagenicity. Additionally, we found that Salmonella typhimurium strain TA98 was more sensitive for the mutagen. Correlation analysis between genotoxicity, Organochlorine Pesticides (OCPs) and Polycyclic Aromatic Hydrocarbons (PAHs) showed that most individual OCPs were frame shift toxicants in drinking water sources, and there was no correlation with total OCPs and PAHs.
Freshwater sources such as rivers, lakes and pond water are used as the primary source of drinking water, irrigation for agricultural purpose and for many human activities around the world. These surface water sources receive large quantities of wastewater from industrial, agricultural, and domestic sources; eventually get polluted and consequently pose a serious threat to human health and indigenous aquatic life. Purification of these surface waters are widely practiced with conventional water treatment processes like coagulation-flocculation, sedimentation, filtration and disinfection. Some reports specified that conventional wastewater purification processes do not effectively remove many chemical contaminants, and treatment may actually increase the mutagenicity/genotoxicity of wastewaters [1–3]. Moreover, these treatment processes are increasingly experiencing operational difficulties due to the widespread pollution of water resources . it is particularly true in China due to the rapid economic growth, swift urbanization and industrialization over the last two decades. The 2005 report on the state of the environment in China showed that water resources still suffered from serious organic pollution, and nearly 60% of the monitored sections of major rivers did not comply with the water quality standards for drinking water supply .
Ames and SOS/umu tests indicated that organic extracts of drinking source water collected from the Guangzhou area induced mutagenicity and genotoxicity. The linear regression analyses indicated that TA98 mutagenic potency was significantly correlated with genotoxicity expressed as IR. Although many individual OCPs might contribute to the mutagenicity observed with the test strain TA98 without S9 mix, no significant correlations were found between mutagenicity and concentrations of total OCPs. OCPs might not be the dominant contaminants for the mutagenicity detected in drinking water sources.