无锡地区出厂水消毒副产物变化趋势及致癌风险研究

Disinfection By-products Tendency and Carcinogenic Risk in Treated Water in Wuxi

目的了解2008—2012年无锡地区出厂水中消毒副产物（DBPs）变化趋势,评估其对成人的致癌风险。方法选取无锡市四家市政供水水厂,于2008—2012年间丰枯水期（8月和2月）采集水样进行监测,监测指标包括4种三卤甲烷类消毒副产物（THMs,三氯甲烷、二氯一溴甲烷、一氯二溴甲烷和三溴甲烷）和两种卤乙酸类消毒副产物（HAAs,二氯乙酸和三氯乙酸）,采用美国环保局推荐的低剂量致癌风险评价方法对其进行评价。结果所有消毒副产物检出值都低于《生活饮用水卫生标准》（GB 5749-2006）[1]的限值。THMs在丰水期的含量高于枯水期的含量,有明显的季节特征。而HAAs则无明显变化规律。无锡地区6种DBPs对成人的致癌风险均超过了USEPA认为可以忽略的水平（〈10-6）,处于具有潜在致癌风险的区间（10-6~10-4）,其中各DBPs总致癌风险从高到低分别为三氯乙酸〉二氯乙酸〉一氯二溴甲烷〉三溴甲烷〉二氯一溴甲烷〉三氯甲烷。结论无锡地区出厂水中THMs有明显的季节性特征,DBPs对成人具有潜在的致癌风险。

Objective To investigate the tendency and carcinogenic risk of disinfection by-products（DBPs） in treated water in Wuxi. Methods Water samples were collected from 4 waterworks in Wuxi during the period of August 2008 to August 2012. Four halomethanes （THMs） and two chloro-haloacetic （chloro-HAAs） were moni- tored. The carcinogenic risk was evaluated by the method recommended by the US Environmental Protection Agency （USEPA）. Results The level of DBPs met the national standards for drinking water（GB 5749 -2006）. There was an obvious seasonal variation of THMs, which were higher in high flow period than in low flow period. No sig- nificant variation was observed for HAAs. The carcinogenic risks of DBPs in Wuxi were all over the negligible levels recommended by USEPA. The rank of DBP levels in water was CHC1302 〉 C2H2C1202 〉 CHBr2C1 〉 CHBr3 〉 CH- BrCI2 〉 CHCl3. Conclusions The level of THMs from treated water in Wuxi were changed greatly with seasonal variation. There was a potential carcinogenic risk of DBPs to adults in Wuxi city.