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美国自来水污染，每年可能导致1.25万例癌症病例
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美国自来水污染，每年可能导致1.25万例癌症病例
诸平
Credit: CC0 Public Domain
Credit: Pixabay.
据美国环境工作小组（Environmental Working Group, EWG）2019年6月11日提供的消息，EWG的一项最新研究成果显示，自来水中的硝酸盐污染每年可能导致1.25万例癌症病例。这项突破性的研究于2019年6月11日在《环境研究》(Environmental Research)杂志网站上发表——Alexis Temkin, Sydney Evans, Tatiana Manidis, Chris Campbell, Olga V. Naidenko. Exposure-based assessment and economic valuation of adverse birth outcomes and cancer risk due to nitrate in United States drinking water. Environmental Research, online 11 June 2019, https://doi.org/10.1016/j.envres.2019.04.009.（点击链接可以直接浏览原文）
美国环境工作组(EWG)一项经过同行评议的最新研究显示，美国饮用水中的硝酸盐污染每年可能导致多达12,594例癌症病例。
EWG的科学家估计，每个州的癌症病例数量都可能与公共供水系统的硝酸盐污染有关，而硝酸盐污染主要是由含有化肥和粪肥的农田径流造成的。他们还估计，每年治疗这些病例的费用高达15亿美元。
EWG高级科学顾问、该研究的作者之一Olga Naidenko博士说:“饮用水中的硝酸盐污染是一个严重的问题，在这个问题在农业国尤其严重。”“现在，我们第一次看到了这种污染（在美国）的惊人后果。”
1962年美国制定的现行联邦饮用水硝酸盐标准是10ppm。然而，几项备受关注的流行病学研究发现，饮用水中的硝酸盐含量与癌症和其他严重健康问题之间的关联，还不到法定限量的十分之一(1ppm)。2019年早些时候，美国环境保护局又暂停了重新评估其过时硝酸盐标准的计划。
EWG估计有五分之四的病例发生是由结直肠癌（colorectal cancer）、卵巢癌（ovarian cancer）、甲状腺癌(thyroid cancer)、肾癌(kidney)以及膀胱癌（bladder cancer）病例构成。自来水中的硝酸盐也与新生儿的严重健康问题有关。EWG估计，硝酸盐污染每年可能导致多达2939例出生体重过低的病例;非常早产1725例;其中神经管缺损41例。
EWG毒理学家、该研究的第一作者亚历克西斯·特金（Alexis Temkin）博士说:“数以百万计的美国人不自觉地暴露在硝酸盐环境中，他们也为处理受污染的自来水付出了沉重的代价。”“但联邦政府在保护美国人免受自来水污染方面做得还不够。”
EWG的科学家估计，饮用水中硝酸盐不会对健康产生负面影响的水平为每公升0.14 mg/L——相当于1ppm。这一水平比EPA的法定上限低70倍，意味着有百万分之一的患癌症风险。更多信息请注意浏览原文或者相关报道。
Highlights
•First of its kind national analysis assessing nitrate exposure from drinking water for the entire U.S. population.
•2,300 to 12,594 nitrate-attributable cancer cases annually in the U.S., of which 54-82% are colorectal cancer (CRC) cases.
•Up to $1.5 and $6.5 billion in medical and indirect costs may be associated with annual nitrate-attributable cancer cases.
•Meta-analysis of eight studies assessing nitrate in drinking water and CRC supports a health benchmark of 0.14 mg/L.
Abstract
Background
Nitrate ingestion from drinking water has been associated with an increased risk of adverse birth outcomes as well as elevated risk of colorectal cancer and several other cancers. Yet, to date, no studies have attempted to quantify the health and economic impacts due to nitrate in drinking water in the United States.
Methods
This study presents a first-of-its-kind comprehensive assessment of nitrate exposure from drinking water for the entire United States population. This exposure assessment serves as the basis for our analysis of the annual nitrate-attributable disease cases in the United States and the associated economic losses due to medical costs and lost productivity. Additionally, through a meta-analysis of studies on drinking water nitrate and colorectal cancer, we examine the exposure-response relationship for nitrate and cancer risk.
Results
On the basis of national nitrate occurrence data and relative risk ratios reported in the epidemiology literature, we calculated that annually, 2939 cases of very low birth weight, 1725 cases of very preterm birth, and 41 cases of neural tube defects could be related to nitrate exposure from drinking water. For cancer risk, combining nitrate-specific risk estimates for colorectal, ovarian, thyroid, kidney, and bladder cancers results in a range of 2300 to 12,594 annual nitrate-attributable cancer cases (mean: 6537 estimated cases). For medical expenditures alone, this burden of cancer corresponds to an annual economic cost of 250 million to 1.5 billion U.S. dollars, together with a potential 1.3 to 6.5 billion dollar impact due to lost productivity. With the meta-analysis of eight studies of drinking water nitrate and colorectal cancer, we observed a statistically significant positive association for nitrate exposure and colorectal cancer risk and calculated a one-in-one million cancer risk level of 0.14 mg/L nitrate in drinking water.
Conclusion
Health and economic analyses presented here suggest that lowering exposure to nitrate in drinking water could bring economic benefits by alleviating the impacts of nitrate-associated diseases.
Original story from the Environmental Working Group.
Study investigates socioeconomic disparities in nitrate levels in US drinking water
Nitrate in drinking water increases the risk of colorectal cancer
Largest-ever study to look at maternal nitrate consumption and birth outcomes
https://blog.sciencenet.cn/blog-212210-1184701.html
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