江苏省南京市饮用水中<i>N</i>-亚硝基二甲胺健康风险评价

郑雨虹; 李登昆; 陈春静; 刘祥萍; 熊丽林

doi:10.11836/JEOM21586

江苏省南京市饮用水中N-亚硝基二甲胺健康风险评价

Health risk assessment of N-nitrosodimethylamine in drinking water in Nanjing, Jiangsu Province

摘要

摘要:
背景 N-亚硝基二甲胺（NDMA）作为新型饮用水消毒副产物，因其较高的检出率和浓度而引起广泛关注。
目的了解我国长江流域下游南京段饮用水中NDMA浓度，并进行健康风险评价。
方法于2021年枯水期（1—3月）和丰水期（7—9月），采集南京市16家集中供水单位的水源水、出厂水及末梢水，采用固相萃取-大体积程序升温进样气相色谱-三重四级杆质谱联用技术测定水样中NDMA的质量浓度（后简称为浓度）。分析不同水样类型、水期和消毒方式的水样中NDMA浓度，计算不同暴露途径和不同暴露人群饮用水中NDMA的日均暴露量和致癌风险值。采用Crystal Ball 11软件实现蒙特卡罗模拟，建立健康风险评价模型，同时进行敏感性分析。
结果共采集南京市生活饮用水水样61份，所有水样均检出NDMA，浓度范围为1.36~25.65 ng·L⁻¹，平均浓度为（8.00±4.06）ng·L⁻¹。水源水、出厂水、末梢水三组水样中NDMA平均浓度差异无统计学意义（F=2.875，P=0.064），丰水期、枯水期水样中NDMA平均浓度差异无统计学意义（t=−0.855，P=0.397），液氯、次氯酸钠、二氧化氯三种不同消毒方式的出厂水中NDMA平均浓度差异无统计学意义（F=0.977，P=0.385）。健康风险评价结果显示，经口摄入饮用水NDMA致癌风险均值为5.95×10⁻⁶，P₉₅为1.12×10⁻⁵，而经皮肤接触的致癌风险均值和P₉₅均低于1.00×10⁻⁶。儿童、青少年、成人饮用水NDMA暴露的致癌风险均值分别为1.84×10⁻⁶、8.27×10⁻⁷和3.28×10⁻⁶。敏感性分析结果显示，日均饮水量和饮用水中NDMA浓度对健康风险的贡献率较大，体重对风险值的贡献为负。
结论长江流域下游南京段饮用水中NDMA存在潜在的致癌风险，但在可接受范围内。

Abstract:
Background N-nitrosodimethylamine (NDMA), a new disinfection by-product in drinking water, has attracted extensive attention due to its high detection rate and concentration.
Objective To investigate the concentration of NDMA in drinking water in Nanjing situated in the lower Yangtze River Basin of China, and to evaluate associated human health risk.
Methods In dry period (January–March) and wet period (July–September) of 2021, raw water, finished water, and tap water from 16 centralized water treatment plants in Nanjing were collected to detect the concentration of NDMA in water samples by solid phase extraction and gas chromatography-triple quadrupole mass spectrometry with programmable temperature vaporizer-based large volume injection. The concentrations of NDMA in water samples of different water types, water periods, and disinfection methods were analyzed, and the daily exposure levels and carcinogenic risk values of NDMA in drinking water of different exposure routes and different exposed populations were calculated. Monte Carlo simulation was implemented with Crystal Ball 11 software to establish a health risk assessment model and conduct sensitivity analysis.
Results A total of 61 drinking water samples were collected in Nanjing, and NDMA was positive in all the water samples, with concentrations ranging from 1.36 to 25.65 ng·L⁻¹ and an overall average concentration of (8.00±4.06) ng·L⁻¹. There were no statistically significant differences in the average concentrations of NDMA among raw water, finished water, and tap water samples (F=2.875, P=0.064), between wet season and dry season (t=−0.855, P=0.397), or among different disinfection methods by liquid chlorine, sodium hypochlorite, and chlorine dioxide (F=0.977, P=0.385). The results of health risk assessment showed that the average carcinogenic risk of NDMA and its P₉₅ were 5.95×10⁻⁶ and 1.12×10⁻⁵ respectively for oral intake of drinking water, and the values for dermal contact were both lower than 1.00×10⁻⁶. The mean carcinogenic risks of exposure to drinking water NDMA in children, adolescents, and adults were 1.84×10⁻⁶, 8.27×10⁻⁷, and 3.28×10⁻⁶, respectively. The results of sensitivity analysis showed that the contributions of daily drinking water volume and NDMA concentration in drinking water to the calculated health risk were high, and the contribution of body weight was negative.
Conclusion There is a potential carcinogenic risk of NDMA in the drinking water of Nanjing section of the lower Yangtze River Basin, but it is within the acceptable range.

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