Rural Drinking Water Quality Health Risk in Rain City District of Ya'an, China
The purpose of this study was to assess exposure to unsafe rural drinking water quality which is the core problem of rural drinking water safety and evaluate the risk of rural drinking water quality among the Rain City District of Ya'an, Sichuan Province, China population. The study calculated the carcinogenic risk (R) and non-carcinogenic risk (hazard index, HI) by applying the health risk model recommended by the US National Research Council of National Academy of Science. Then, taking advantage of the geo-statistic spatial analysis function of ArcGIS, this study analyzed the assessment result data (R and HI), selected the proper interpolation approach and educed R and HI spatial distribution maps in the study area. The following conclusions can be drawn: most of the cancerous risk indexes belong to the unsafe extension, the main carcinogen in water sources were As, Cr6+ and Pb, their concentrations are in the ranges of 0.004-0.005, 0.0005-0.015, 0.01mg/l respectively; the measured concentration values of fluoride, As, Hg and Nitrate of all the 12 water sources didn't exceed Guidelines for Drinking Water Quality of WHO (Third Edition, 2008) limit values; the total non-cancerous risk of No.1-8 and 12 of all the 12 drinking water source investigation sites exceeded the drinking water management standard value of EPA (the limit value is 1), exceeded up to about 1.109-2.373 times. Hence there were tendency of producing non-carcinogenic, chronic and poisoning effects on drinking crowd, about 105757 residents are exposed to such drinking water environment. The effective way of decreasing the health risk and hazard was to control and dispose the rural drinking water containing Fe, Mn, fluoride, Hg, Cd, Cr6+ and Nitrate. The results provided important information of water quality control and the early warning for rural drinking water.