我国城市饮用水中N-亚硝基二甲胺的健康风险评估及水质标准制定

Estimation of Health Risk and Enaction of Safety Standards of N-nitrosodimethylamine(NDMA) in Drinking Waters in China

亚硝胺类物质,特别是亚硝基二甲胺(NDMA),其高致癌性及在我国饮用水中高检出率引起了国内媒体和管理层的广泛关注.为了评价饮水中NDMA造成的健康风险,进而提出我国饮水标准的建议,本文利用近几年全国饮用水水质调查的NDMA数据,以伤残调整寿命年(DALYs)为风险评价终点,并结合疾病模型,对饮水途径摄入NDMA造成的健康风险进行估算.结果表明,我国城市饮用水中由于NDMA造成的终身癌症发病率为5.69×10^(-6),人均DALYs损失为6.27×10^(-7)人·a^(-1).以WHO所推荐的风险可接受水平(DALYs)(10^(-6)人·a^(-1))来制定饮用水中NDMA浓度安全标准,应为6.12 ng·L^(-1).考虑到我国水厂工艺情况,未来NDMA的安全标准设在6~40 ng·L^(-1)范围内更合理.最终的水质标准仍需进一步考虑其他经济和技术水平等因素.

Nitrosamines such as nitrosodimethylamine（NDMA） in drinking water have recently attracted great attention because of their high carcinogenicity and high detection rate. Nitrosamines have also been repeatedly detected in drinking water in our country, leading to a lot of concerns about our drinking water safety. However, China has not yet formulated the relevant drinking water safety standards. In order to evaluate the health risks caused by NDMA in drinking water and to provide recommendations for the development of drinking water safety standards, the method of disability-adjusted life years（DALYs） and the two-stage disease model were used to estimate the health risk of liver cancer caused by intake of NDMA in drinking water. The data of this study were collected from two large-scale water quality surveys conducted in 35 cities in China from November 2009 to May 2012, and the detection conducted by Chen Chao et al. in 23 cities in China from 2012 to 2014, with a total of 146 water plants data. The results showed that mean（8.97 ng·L^-1） and median（2.90 ng·L^-1） NDMA concentrations were both not very high except in some special areas. The incidence of life-long cancer was 5.69×10^-6 and 5.69 times as high as the negligible risk value（1×10^-6） specified by the US EPA. The total disease burden of NDMA was 844.15 person-years, of which the death loss was 818.31 person-years, accounting for 96.9%. The incapacity loss was 25.84 person-years, accounting for 3.1% in comparison. Death loss was greater than the loss of incapacity. The disease burden was highest in the age group of 55-60 years（129.40 person-years）, followed by 45-50 years（120.44 person-years）. The burden of disease was higher in middle-aged and elderly people. The averaged loss was 6.27×10^-7 DALYs per person per year in our country. Only considering the health risk factors, NDMA concentration safety standards should be 6.12 ng·L^-1. According to the specific national conditions, the NDMA safety standard in the range of 6-40 ng·L^-1 was recommended. On one hand, we can control the concentration of NDMA in drinking water, to reduce health risks as far as possible, and on the other hand, we can also ensure the effectiveness of disinfection of drinking water treatments. China＇s economic and water treatment technological level and other factors should also be taken into consideration in the near future. In view of potential health risks of NDMA, it＇s necessary to adopt more effective, economical and also environmental water treatment techniques and develop reasonable safety standards to ensure the quality of drinking water and people＇s health.