兰州市西固区儿童饮用水重金属暴露及健康风险精细化评估

饮用水是人体暴露重金属的重要途径之一,准确评估人体经饮用水暴露重金属的健康风险对其采取有针对性地健康风险防范措施具有重要意义.为探索并准确识别兰州市西固区人群经饮用水途径对重金属暴露的健康风险,本研究于2015年7～9月(非采暖期)和2015年12月～2016年1月(采暖期)开展现场入户调查,采集当地0～5岁和6～17岁儿童的饮水和用水样品,并开展人群饮用水行为模式问卷调查.通过饮水和用水中Cd、Cr、Pb和As的浓度分析,结合儿童饮用水暴露行为模式特征,采用美国环保署推荐的暴露和健康风险评价模型开展儿童饮水和用水重金属暴露的健康风险研究.结果表明,两种水体中Cd、Cr、Pb和As的浓度均未超过国家生活饮用水卫生标准限值,用水重金属的浓度受季节性影响较大,而饮水较小.饮水和用水中4种重金属的非致癌和致癌风险水平范围分别为2. 82E-08～2. 43E-02和7. 55E-09～3. 62E-05,均处于可接受风险水平;但饮水中重金属的致癌和非致癌健康风险均高于用水.同一时期0～5岁儿童用水重金属暴露的致癌和非致癌风险均低于6～17岁;而0～5岁儿童饮水中重金属暴露的致癌风险低于6～17岁,非致癌风险却高于6～17岁.研究表明该地区饮水/用水重金属暴露不会对人体健康产生明显危害,精细化的暴露评估方法可减少健康风险评估的不确定性.

Refined Assessment of Exposure and Health Risks of Heavy Metals in Water for the Children in Xigu District, Lanzhou

Water is an important pathway for human exposure to heavy metals. Accurate assessment of the health risks that are related to exposure to heavy metals in drinking and household water are required for the preparation of targeted health risk prevention measures. This study explores and identifies the health risks related to exposure to heavy metals via drinking and household water pathways in Xigu District, Lanzhou, northwestern China, using household water samples and survey data obtained during July-September 2015 (wet season) and December 2015-January 2016 (dry season). During each period, drinking water and household water that were available for use by children aged 0-5 and 6-17 years were sampled and a questionnaire on water-related behavior patterns was completed for each household. Cd, Cr, Pb, and As concentrations were analyzed in all water samples, and were used along with water-related exposure factors from the questionnaires to estimate exposure doses and associated health risks using models recommended by the United States Environmental Protection Agency (US EPA). The results showed that the concentrations of Cd, Cr, Pb, and As in both drinking and household water samples did not exceed the relative thresholds defined in China''s national water quality standards. The concentrations of heavy metals in household water were more affected by seasonal factors than of those of drinking water. The non-cancer and cancer risks were in the ranges of 2.82×10^-8-2.43×10^-2 and 7.55×10^-9-3.62×10^-5, respectively, which are within acceptable levels, although the non-cancer and cancer risks from drinking water were both higher than of those determined for household water. Furthermore, the non-cancer and cancer risks from household water for children aged 0-5 years were lower than of those for children aged 6-17 years in each period. However, the cancer risk from drinking water for children aged 0-5 years was lower than of that for children aged 6-17 years, whereas the reverse was found for non-cancer risks. This study indicates that Cd, Cr, Pb, and As in drinking and household water did not pose significant detrimental effects to human health, and that the refined exposure assessment used could reduce uncertainties in health risk assessments.