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AACR Environmental Carcinogenesis: Lowering Exposure to Nitrates in Drinking Water May Reduce U.S. Cancer Cases

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Key Points

  • Up to 12,594 cases of colorectal, ovarian, thyroid, kidney, and bladder cancers each year may be attributable to nitrate pollution in drinking water. A statistically significant positive association for nitrate exposure and colorectal cancer risk was calculated at a 1-in-1 million cancer risk level of 0.14 mg/L nitrate in drinking water.
  • Medical expenditures for nitrate-related cancers are between $250 million and $1.5 billion each year, and lost productivity impact is potentially between $1.3 billion and $6.5 billion.

Nitrate levels in water resources have increased in many areas of the world, largely due to the use of inorganic fertilizer and animal manure in agricultural areas. Research has shown that the risk of specific cancers and birth defects may be increased when nitrate is ingested under conditions that increase levels of N-nitroso compounds.

A study by Temkin et al assessing nitrate exposure from drinking water and associated diseases has found that very low birth rate and birth defects, as well as several types of cancer—especially colorectal cancer—may be associated with nitrate exposure. The study is being presented at the American Association for Cancer Research conference on Environmental Carcinogenesis: Potential Pathway to Cancer Prevention.

Methods

Researchers from the Environmental Working Group performed a comprehensive assessment of nitrate exposure from drinking water from public water systems in the United States, largely caused by farm runoff containing fertilizer and manure. They also estimated medical expenditures and lost productivity as a result of diseases caused by nitrate pollution in drinking water.

Results

On the basis of national nitrate occurrence data and relative risk ratios reported in the epidemiology literature, the researchers calculated that annually, there are 2,939 cases of very low birth weight; 1,725 cases of very preterm birth; and 41 cases of neural tube defects that are related to nitrate exposure from drinking water.

For cancer risk, after combining nitrate-specific risk estimates for colorectal, ovarian, thyroid, kidney, and bladder cancers, the researchers found a range of between 2,300 and 12,594 annual nitrate-attributable cancer cases (mean: 6,537 estimated cases). For medical expenditures, they found that the annual cost of treating these cancers was between $250 million and $1.5 billion, and lost productivity impact was calculated as potentially being between $1.3 billion and $6.5 billion.

With a meta-analysis of eight studies of drinking nitrate in water and colorectal cancer, the investigators observed a statistically significant positive association for nitrate exposure and colorectal cancer risk and calculated a 1-in-1 million cancer risk level of 0.14 mg/L nitrate in drinking water.

“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,” concluded the study authors.

Disclosure: For full disclosures of the study authors, visit aacr.org.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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