Drinking Water Nitrate and Health – Recent Findings and Research Needs

Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892, USA.
Environmental Health Perspectives (Impact Factor: 7.98). 12/2005; 113(11):1607-14. DOI: 10.1289/ehp.8043
Source: PubMed


Human alteration of the nitrogen cycle has resulted in steadily accumulating nitrate in our water resources. The U.S. maximum contaminant level and World Health Organization guidelines for nitrate in drinking water were promulgated to protect infants from developing methemoglobinemia, an acute condition. Some scientists have recently suggested that the regulatory limit for nitrate is overly conservative; however, they have not thoroughly considered chronic health outcomes. In August 2004, a symposium on drinking-water nitrate and health was held at the International Society for Environmental Epidemiology meeting to evaluate nitrate exposures and associated health effects in relation to the current regulatory limit. The contribution of drinking-water nitrate toward endogenous formation of N-nitroso compounds was evaluated with a focus toward identifying subpopulations with increased rates of nitrosation. Adverse health effects may be the result of a complex interaction of the amount of nitrate ingested, the concomitant ingestion of nitrosation cofactors and precursors, and specific medical conditions that increase nitrosation. Workshop participants concluded that more experimental studies are needed and that a particularly fruitful approach may be to conduct epidemiologic studies among susceptible subgroups with increased endogenous nitrosation. The few epidemiologic studies that have evaluated intake of nitrosation precursors and/or nitrosation inhibitors have observed elevated risks for colon cancer and neural tube defects associated with drinking-water nitrate concentrations below the regulatory limit. The role of drinking-water nitrate exposure as a risk factor for specific cancers, reproductive outcomes, and other chronic health effects must be studied more thoroughly before changes to the regulatory level for nitrate in drinking water can be considered.

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    • "This compound has become an increasingly human health problem, as by the end of the 19th century the rate of creation of reactive nitrogen in the world has increased about tenfold due to anthropogenic activities and it is estimated that human interference with the nitrogen cycle has already exceeded the safe operating boundary of the Earth by a factor of 3.5 (Gao et al., 2014). Although still controversial, the ingestion of drinking water nitrate, especially in concentrations above the regulatory limit of 50 mg/L in the European Union (Nitrates Directive, 91/676/CEE), seems to favor endogenous formation of N-nitroso compounds (Shephard and Lutz, 1989) which in turn increases the risk of cancer in adults (Khademikia et al., 2013), methemoglobinemia in children (Ward et al., 2005), and adverse reproductive outcomes. These evidences concern public health organizations because the population exposed to nitrate levels in drinking water above 50 mg/L is very large worldwide, reaching 10 million people in 15 European countries (WHO, 2011). "
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