某地区不同供水方式下农村居民饮水微生物定量风险评价

Quantitative microbial risk assessment of different drinking water supply systems for rural residents

目的评价农村地区居民在不同供水方式下微生物暴露健康风险。方法以贵州省黎平县某村作为研究对象,采用微生物定量风险评价方法评价该村居民在使用不同供水方式(集中式供水或分散式供水)、居民在不同家庭水处理方式下(是否煮沸)的微生物感染风险概率。结果调查村的集中式供水末梢水水样菌落总数超标率为45.45%,总大肠菌群超标率为100.00%;分散式供水水样菌落总数和总大肠菌群超标率均为100.00%。微生物定量风险评价结果显示,当居民使用正常消毒的集中式供水时个体感染致病性微生物的年风险概率为8.85×10^(-4)(5.34×10^(-4)~14.71×10^(-4)),使用非正常消毒的集中式供水时为844.93×10^(-4)(519.64×10^(-4)~1362.58×10^(-4)),均低于饮用分散式供水时个体感染致病性微生物的年风险概率[1044.53×10^(-4)(967.68×10^(-4)~1126.97×10^(-4))],差异有统计学意义(t=688.92,P<0.05)。居民在使用分散式供水时,饮用开水时个体感染致病性微生物的年风险概率为197.93×10^(-4)(182.21×10^(-4)~215.17×10^(-4)),低于饮生水个体的年风险概率[1108.63×10^(-4)(1024.58×10^(-4)~1200.08×10^(-4))],差异有统计学意义(F=10744.16,P<0.05)。结论提高人群集中式供水人口使用率、加强饮水消毒和促进居民饮用前将水煮沸可显著降低居民的饮水微生物暴露风险。

Objective To assess the risk of exposure to microorganisms for rural residents using different water supply.Methods A village in Liping county,Guizhou province was selected as the study region.Quantitative microbial risk assessment(QMRA)was used to evaluate the probability of microbial infection in residents consuming drinking water from different sources(centralized and decentralized water supply)and using different household water treatment(boiling and not boiling).Results In the surveyed village,45.45%of the tap water samples from the centralized water supply were found to have colony counts above the limit,and 100.00%showed over-limit coliforms count;the figures for the sample from the decentralized water supply were both 100.00%.QMRA results showed that the annual probability of infection with pathogenic micro0rganisms when using a disinfected centralized water supply was 8.85×10^(-4)(5.34×10^(-4)-14.71×10^(-4)),but 844.93×10^(-4)(519.64×10^(-4)-1362.58×10^(-4))when using an unsterilized centralized water supply,which were both statistically significantly lower than the probability of infection when using drinking water from a decentralized water supply[1044.53×10^(-4)(967.68×10^(-4)-1126.97×10^(-4))](t=688.92,P<0.05).When using a decentralized water supply,the annual probability of infection with pathogenic microorganisms was 197.93×10^(-4)(182.21×10^(-4)-215.17×10^(-4))if the drinking water was boiled,statistically significantly lower than the annual probability of infection if the drinking water was unboiled[1108.63×10^(-4)(1024.58×10^(-4)-1200.08×10^(-4))(F=10744.16,P<0.05).Conclusions Expanding the coverage of centralized water supply,enhancing disinfection of drinking water and educating residents to boil water before drinking may reduce the risk of exposure to water-borne microorganisms.