西安市已改水地方性氟中毒病区饮水中元素分布特征及健康风险评估

Distribution characteristics and health risk assessment of elements in drinking water from endemic fluorosis areas with water improvement in Xi'an City

目的分析西安市已改水地方性氟中毒(简称地氟病)病区饮水中元素种类及分布特征,了解氟化物与各元素之间的关系,评估潜在高风险元素的健康风险。方法2017年5-6月,在西安市按照东北、西南、正东方位各选择1个已改水地氟病病区(高陵区、鄠邑区、临潼区)作为调查病区,每个病区选择16个地氟病病区村,每个病区村采集2份水样,检测氟化物和铬、锰、铁、铜、锌、砷、硒、钼、镉、锑、钡、铅12种元素含量;参照国家标准进行卫生学评价,并应用美国国家环境保护局推荐的健康风险评估模型对潜在高风险元素砷、钼进行健康风险评估。结果西安市3个已改水地氟病病区饮水中主要含钡、铁、钼、砷、锌、锰、铬7种元素,而铜、硒含量较低,镉、锑、铅含量极低。高陵区、临潼区饮水氟化物含量较高,氟-砷-钼元素含量两两呈正相关(均P<0.05);临潼区水样钼元素含量超标率为9.38%(3/32);鄠邑区饮水氟化物含量较低,砷-钼元素含量呈正相关(r=0.84,P<0.001),且砷元素含量超标率为25.00%(8/32)。西安市已改水地氟病病区饮水途径主要健康风险是砷暴露健康风险,且儿童高于成人,鄠邑区>临潼区>高陵区,其中高陵区在可接受水平[致癌风险评估值(CR)<10^(-4),危害商(HQ)<1],而鄠邑区、临潼区(除成人的砷暴露HQ)则有较高的风险(CR>10^(-4),HQ>1)。临潼区有1个地氟病病区村的儿童钼元素非致癌风险较高(HQ>1)。结论西安市已改水地氟病病区饮水中主要含7种元素,特别是砷、钼需定期监测,部分病区水砷含量健康风险较高,需加强监测、管理和相关的流行病学调查。同时,改水降氟工作需积极监测改水过程中可能引入的其他有毒有害物质,预防次生健康问题的发生。

Objective To analyze the types and distribution characteristics of elements in drinking water from endemic fluorosis areas with water improvement in Xi'an City,understand the relationship between fluoride and various elements,and conduct health risk assessment on potential high-risk elements.Methods From May to June 2017,one endemic fluorosis area with water improvement(Gaoling District,Huyi District,Lintong District)was selected according to the northeast,the southwest and the due east directions of Xi'an City as the survey area.Sixteen endemic fluorosis villages were selected from each endemic area,and 2 water samples were collected from each endemic village to detect fluoride and 12 elements such as chromium,manganese,ferrum,copper,zinc,arsenic,selenium,molybdenum,cadmium,antimony,barium,and lead.Hygienic evaluation was conducted according to national standards,and the potential high-risk elements(arsenic,molybdenum)were assessed for health risk through the health risk assessment model recommended by the National Environmental Protection Agency of the United States.Results The water samples from the endemic fluorosis areas in Xi'an City mainly contained seven elements:barium,ferrum,molybdenum,arsenic,zinc,manganese,and chromium.The content of copper and selenium was relatively low,while the content of cadmium,antimony,and lead was extremely low.The fluoride content in water samples from Gaoling District and Lintong District was relatively high,and the fluorine,arsenic,molybdenum elements was pairwise positively correlated(P<0.05).The molybdenum element in water samples from Lintong District exceeded 9.38%(3/32).The fluoride in the water samples of Huyi District was relatively low,and the arsenic,molybdenum elements was positively correlated(r=0.84,P<0.001),and the arsenic element exceeded the standard by 25.00%(8/32).The main health risk of drinking water in endemic fluorosis areas with water improvement in Xi'an City was arsenic exposure,with children at a higher risk than adults,and the areas of Huyi District,Lintong District,and Gaoling District declined,the risk of cancer(CR)of Gaoling District was<10^(-4) and hazard quotient(HQ)was<1.However,in the areas of Huyi District and Lintong District(except HQ of adults),there was a higher risk(CR>10^(-4),HQ>1).Children in one endemic fluorosis village in Lintong District had a higher non carcinogenic risk of molybdenum(HQ>1).Conclusions The drinking water in endemic fluorosis areas with water improvement in Xi'an City mainly contains 7 elements,especially arsenic and molybdenum,which need to be regularly monitored.Some areas have high health risks of arsenic in water,and monitoring,management,and related epidemiological investigations need to be strengthened.At the same time,it is necessary to actively monitor other toxic and harmful substances that may be introduced during the water improvement process to prevent the occurrence of secondary health problems.