宁夏村镇饮用水中重金属暴露健康风险评估及不确定性分析

Health Risk Assessment and Uncertainty Analysis Based on Heavy Metals Exposure by Drinking Water in Ningxia Rural Areas

确定宁夏农村饮用水中重金属浓度,对保障宁夏居民饮水健康具有重要的意义。通过对宁夏回族自治区5个村镇饮用水采样调研,采用电感耦合等离子体-原子发射光谱(ICP-AES)法分析饮用水中5种常见重金属(砷、铬、镉、铅和铜)的浓度,并与我国《生活饮用水卫生标准》相比较,计算超标率;通过健康风险评估模型系统评价居民基于重金属污染的健康风险,进一步通过不确定性分析风险概率及敏感性。结果表明,5个采样点饮用水中砷元素均有超标现象(超标率<20%),其他4种重金属均未超标;5个样点饮用水中重金属单独暴露或共同暴露均不产生非致癌风险,但是砷元素所引起的致癌风险均超过美国环境保护局(US EPA)推荐的最大可接受风险水平10-4;不确定性分析中,概率评估结果显示对>90%的居民不存在非致癌风险,而对50%以上居民的致癌风险大于最大可接受风险水平;敏感性分析结果显示,非致癌风险中砷浓度和日摄入量为最敏感的2个参数,而致癌风险中砷浓度为最敏感参数。

Determining the heavy metal concentration of drinking water in Ningxia rural areas is of significance in ensuring drinking water security for inhabitants.In this study,we collected drinking water from five different villages and analyzed the concentrations of five common heavy metals(arsenic,chromium,cadmium,lead and copper)using inductively coupled plasma-atomic emission spectrometry(ICP-AES)method.Exceeding ratio was calculated by comparing with“hygienic standard for drinking water”in China.Based on health risk model,health risk was evaluated,and probability assessment and sensitivity analysis were taken by uncertainty analysis.Results showed that arsenic concentrations of less than 20%of the samples in five sampling sites exceeded the standard,while the concentrations of other four heavy metals not.The five metals could not cause obvious non-carcinogenic risk in each sampling site no matter individual risk or combined risk,while arsenic could increase carcinogenic risk due to its risk value over the maximum acceptable level set by United States Environmental Protection Agency(US EPA)(10-4).In uncertainty analysis,probability assessment results indicated that more than 90%of the population had no non-carcinogenic risk,but more than 50%of residents might have carcinogenic risk which exceeded the acceptable level;sensitivity analysis results suggested arsenic concentration and daily intake were the most sensitive factors in non-carcinogenic risk,and arsenic concentration was the key factor in carcinogenic risk.