Exposure level and health risk of hexavalent chromium in rural drinking water in Shaanxi province based on GIS technology
Objective To understand the exposure level and health risk of hexavalent chromium in rural drinking water in Shaanxi Province.Methods A stratified random sampling method was used to collect 250 rural water supply projects in Shaanxi province from April to May 2019,and to detect the concentration of hexavalent chromium in rural drinking water.The distribution characteristics of hexavalent chromium were analyzed based on GIS technology,and the carcinogenic health risk of residents was evaluated with a health risk assessment model.Results The concentration range of hexavalent chromium in 250 rural drinking water samples was undetected to 0.138,with a median of 0.007 mg/L and a qualification rate of 91.2％.The concentrations range in the Guanzhong region,southern Shaanxi,and northern Shaanxi were from undetected to 0.138,undetected to 0.035,and undetected to 0.120 mg/L,respectively.The concentration of hexavalent chromium in rural drinking water in northern Shaanxi(median 0.018 mg/L)was the highest,followed by Guanzhong(median 0.007 mg/L),and southern Shaanxi(median 0.002 mg/L)was the lowest,with significant differences(P＜0.05).The qualified rate of rural drinking water samples in southern Shaanxi(100.0％)＞central Shaanxi(93.3％)＞northern Shaanxi(80％),with significant differences(P＜0.05).The carcinogenic risk of hexavalent chromium in rural drinking water in northern Shaanxi＞guanzhong region＞southern Shaanxi,and the carcinogenic risk of hexavalent chromium in rural drinking water in southern Shaanxi is within the acceptable range of EPA;In addition,the carcinogenic risk of hexavalent chromium caused by drinking water in adults was lower than that in children.Spatial interpolation analysis showed that the carcinogenic health risk caused by hexavalent chromium in drinking water was higher in some areas of northern Shaanxi and Guanzhong regions,with the distribution characteristics in Shaanxi province were high in the northwest and low in the southeast.Conclusion The contamination status of hexavalent chromium in Shaanxi province present obvious regional characteristics,and exist potential health risks in some areas.
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