上海市饮用水中亚硝胺类化合物的污染状况及健康风险评估
Distribution and health risk assessment of nitrosamines in drinking water in Shanghai
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摘要:
背景 亚硝胺类化合物（NAms）致癌性强，在我国饮用水中检出率高，存在饮水途径摄入的风险。
目的 了解上海市饮用水中NAms的污染状况，并进行健康风险评价。
方法 2021年枯水期（2月）和丰水期（8月）采集上海市30个水厂的原水水样共94份、出厂水水样共120份，采用固相萃取-气相色谱质谱法，测定水中8种NAms的质量浓度（后称：浓度），应用美国环保局推荐的致癌物质健康风险模型结合蒙特卡洛概率法，评估不同年龄人群不同途径经水暴露于NAms造成的致癌风险。
结果 原水和出厂水中总NAms的浓度范围分别为12.56~65.86 ng·L−1和8.52~57.38 ng·L−1。总NAms平均浓度在枯水期为原水（33.50 ng·L−1）高于出厂水（22.07 ng·L−1，P<0.05），在丰水期为原水（16.90 ng·L−1）低于出厂水（21.02 ng·L−1，P<0.05）；且枯水期原水中总NAms的平均浓度是丰水期的2倍。8种NAms中，N-亚硝基二甲胺（NDMA）检出率最高（100%）。上海市出厂水中NAms对人群造成的致癌风险以饮水途径为主，主要由NDMA贡献。儿童经水暴露于NAms的致癌风险（中位数为4.32×10−5）略高于成人（中位数为3.34×10−5）和青少年（中位数为2.27×10−5）。不同年龄人群经水暴露于NAms的致癌风险较大比例（80%~95%）处于可接受水平（1×10−6~1×10−4）。
结论 上海市饮用水中存在NAms污染，以NDMA为主。现有水厂处理工艺对NAms的去除作用具有季节依赖性。儿童经水暴露于NAms的致癌风险略高于成人和青少年，但均处于可接受水平。
Abstract:Background Nitrosamines (NAms) are highly carcinogenic and frequently detected in drinking water systems in China, indicating potential human health risk through drinking water.
Objective To analyze the distribution of NAms in drinking water in Shanghai and to evaluate relevant human health risk.
Methods A total of 94 samples of source water and 120 samples of finished water were collected in February (dry period) and August (wet period) of 2021 from 30 drinking water plants in Shanghai, and eight NAms were quantitatively analyzed by gas chromatography tandem mass spectrometry after solid phase extraction. Cancer risks for different age groups caused by NAms exposure through water were evaluated using Monte Carlo probabilistic method and carcinogens risk assessment model recommended by the United States Environmental Protection Agency.
Results The concentrations of total NAms in source and finished water were 12.56-65.86 ng·L−1 and 8.52-57.38 ng·L−1, respectively. The average concentration of total NAms was higher in source water (33.50 ng·L−1) than in finished water (22.07 ng·L−1, P<0.05) during dry season, and lower in source water (16.90 ng·L−1) than in finished water (21.02 ng·L−1, P<0.05) during wet season. The average concentration of total NAms in source water during dry season was twice of that during wet season. The positive rate of N-nitrosodimethylamine (NDMA) was the highest (100%) among the eight NAms. The cancer risk of exposure to NAms in finished water in Shanghai was mainly from the ingestion route, which was mostly caused by NDMA. The cancer risk from exposure to NAms in water for children (median=4.32×10−5) was slightly higher than that for adults (median=3.34×10−5) and adolescents (median=2.27×10−5). The cancer risks of exposure to NAms in water for people of different ages were mainly (80% - 95%) at an acceptable level (1×10−6 - 1×10−4).
Conclusion NAms contamination is positive in Shanghai’s drinking water and NDMA is the main contaminant. The removal of NAms in water by current water treatment process is season-dependent. The cancer risk of children exposed to NAms in water was slightly higher than that of adults and adolescents, but all at acceptable levels.
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