Health risk assessment of trichlormethane in school drinking water of Jiangsu Province
Objective To investigate the distribution characteristics of trichlormethane in school drinking water in Jiangsu Prov-ince,and to evaluate the health risks and influencing factors of students exposed to trichlormethane,so as to provide a scientific ba-sis for the disinfection and safety of school drinking water.Methods A total of 315 schools(123 primary schools,142 junior high schools,20 high schools,and 30 universities)in Jiangsu Province were selected by a stratified sampling method.Water samples in the wet period(from July to September)of 2023 and in the dry period(from January to March)of 2024 in each school were collect-ed,and 630 drinking water samples were collected.According to the Standard Examination Methods for Drinking Water(GB/T 5750-2023),drinking water samples were analyzed for trichlormethane,and the health risks of trichlormethane exposure in drink-ing water for students were assessed using the health risk assessment method recommended by US Environmental Protection Agency.The Kruskal-Wallis H rank sum test and Mann-Whitney U test were performed to analyze concentrations and health risks of tri-chlormethane in school drinking water in different groups.Results The concentration of trichlormethane in school drinking water in Jiangsu Province was 8.9(4.6,14.0)μg/L.The carcinogenic risk of trichlormethane in school drinking water was 9.8× 10-6(5.3× 10-6,1.7×10-5),which was an acceptable low risk.The amount of drinking water per unit body weight and the concentration of tri-chlormethane in tap water samples were important factors affecting the carcinogenic risk in drinking water for students.Comparison of carcinogenic risks exposed to trichlormethane in drinking water were as follows:primary school students in lower grades had the highest risk of carcinogenesis,with a risk of 1.2×10-5,the wet period(1.3×10-5)＞the dry period(7.6×10-6),river source water(1.0×10-5)＞lake source water(6.8× 10-6),liquid chlorine disinfection(1.1×10-5)＞sodium hypochlorite disinfection(9.3× 10-6),conventional treatment(1.4×10-5)＞advanced treatment(9.6×10-6),with statistically significant differences(Z=88.1,3.7,-3.2,-2.7,P＜0.05).The non-carcinogenic risk of trichlormethane in school drinking water was 1.4×10-2 for less than 1,and the non-carcinogenic risk was acceptable.Conclusions The carcinogenic and non-carcinogenic risks of trichlormethane in school drinking water are acceptable in Jiangsu Province,and the primary school students in lower grades are key indicators for risk management of trichlormethane in drinking water.According to the characteristics of the source water,appropriate disinfection meth-ods and water treatment processes are selected to reduce the content of trichlormethane and control health risk.
DrinkingTrichloromethaneRisk assessmentStudents health services
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