Department of Civil, Architectural and Environmental Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania 19104, USA.
J Expo Sci Environ Epidemiol. 2010 May;20(3):245-54. doi: 10.1038/jes.2009.24. Epub 2009 Apr 29.
Although approximately 35 million people in the US obtain drinking water from domestic wells, few studies have investigated the risk of arsenic exposure from this source. In this paper arsenic concentrations were modeled for public and domestic wells using a dataset from the US Geological Survey (USGS). Excess lifetime and annual risks for lung and bladder cancer were calculated based on the carcinogenic potency and average arsenic concentrations in public and domestic water supplies. Monte Carlo uncertainty analysis was used to estimate the degree of confidence in these estimations. Results indicated that domestic well users accounted for 12% of the US population, but 23% of overall arsenic exposure from drinking water. Assuming that the new and more restrictive arsenic maximum contaminant limit (MCL) is implemented for public water supplies, it is anticipated that the proportion of people experiencing excess annual fatalities from drinking water from domestic wells will increase to 29% unless corresponding efforts are made to reduce exposures among domestic well users. Differences between public and domestic wells were not consistent across the nation. Public wells tend to tap deeper aquifers than domestic wells, and as a result local arsenic-depth trends can contribute to differences between public and domestic wells. Domestic wells and public wells in the western US have the highest arsenic levels with excess fatality risks estimated to be in the range of 1 per 9300 to 1 per 6600 in these regions. Uncertainty distributions of excess fatalities were developed and resultant uncertainties were propagated in arsenic exposure and potency factor. Uncertainty in the carcinogenic potency of arsenic was the dominant source of uncertainty in most regions, but for domestic wells in the New England and Southeast regions uncertainty in arsenic exposure was dominant, indicating that additional data on arsenic concentrations in these areas would substantially improve regional risk estimates.
尽管美国约有 3500 万人从家用井中获取饮用水，但很少有研究调查过从这一来源摄入砷的风险。在本文中，我们使用美国地质调查局（USGS）的数据对公共和家用井中的砷浓度进行建模。根据公共和家用供水中的致癌效力和平均砷浓度，计算了肺癌和膀胱癌的超额终生和年度风险。蒙特卡罗不确定性分析用于估计这些估计的置信度。结果表明，家用井用户占美国人口的 12%，但占饮用水中砷总暴露量的 23%。假设新的、更严格的砷最大污染物限量（MCL）适用于公共供水，那么除非在国内水井用户中采取相应措施减少暴露，否则预计饮用家用井水导致的年度死亡人数将从目前的 23%增加到 29%。公共井和家用井之间的差异在全国范围内并不一致。公共井往往比家用井更深地抽取含水层，因此当地的砷深度趋势会导致公共井和家用井之间的差异。美国西部的家用井和公共井砷含量最高，据估计，这些地区的超额死亡风险在每 9300 到每 6600 人之间。我们还开发了超额死亡的不确定性分布，并在砷暴露和效力因子中传播了由此产生的不确定性。砷致癌效力的不确定性是大多数地区不确定性的主要来源，但在新英格兰和东南部地区的家用井中，砷暴露的不确定性占主导地位，这表明在这些地区增加砷浓度的额外数据将大大提高区域风险估计。
