Content monitoring and risk assessment of trihalomethanes in drinking water in a certain district of Hangzhou City,2021-2022
Objective To understand the distribution level of trihalomethanes(THMs)disinfection byproducts in domestic drinking water in a certain district of Hangzhou City,and to evaluate the possible health risks to human beings.Methods The concentration of trihalomethanes in factory-treated water and tap water in the district of Hangzhou City during 2021-2022 was detected by headspace gas chromatography,and the risk assessment was conducted based on the health risk model recommended by the United States Environmental Protection Agency.Results The distribution of THMs content in drinking water in the district of Hangzhou City in 2021-2022 was ND-44.12 pg/L,the detection rate(100.00％)and average content(18.76 pg/L)of chloroform were the highest.In the comparison between groups,no significant difference was found in the distribution of THMs content between 2021 and 2022(P＞0.05).The content of THMs was higher in the wet period than in the dry period as well as higher in the tap water than in the factory-treated water(P＜0.05).Carcinogenic risks(1.38×10-5 and 1.26× 10-5)and non-carcinogenic risk(6.46× 10-2 and 5.92 × 10-2)of THMs for males and females were within the acceptable ranges,with chloroform contributing the largest risks of carcinogenesis(50.14％)and non-carcinogenesis(80.32％).Conclusion THMs content in domestic drinking water in the district of Hangzhou City during 2021-2022 conformed to the limits as specified in the Standard Examination Methods for Drinking Water(GB/T 5750-2006).The health risks of THMs to human beings are within an acceptable range,with chloroform having the highest health risk and requiring special attention.In addition,it is necessary to strengthen the risk monitoring and evaluation of THMs in the wet period and in tap water.
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