Drinking water nitrate and human health: An updated review

Summary

This updated systematic review synthesises epidemiologic evidence from over 30 studies on drinking water nitrate exposure and human health outcomes. The review identifies colorectal cancer, thyroid disease, and neural tube defects as having the strongest evidence for association with nitrate ingestion, with particular concern that increased risks were observed at water nitrate levels below current regulatory limits. The authors note that existing drinking water standards were set solely to prevent infant methemoglobinemia and did not account for these other health risks.

Regional applicability

Nitrate contamination of drinking water is a significant concern in agricultural regions of the United Kingdom, particularly in eastern England and areas with intensive arable and livestock farming. The findings support the need for review of UK drinking water standards and exposure assessment methodologies, though UK-specific epidemiologic data on health outcomes would strengthen evidence for policy application.

Key measures

Drinking water nitrate concentration; incidence of colorectal cancer, bladder cancer, breast cancer, thyroid disease, neural tube defects, and methemoglobinemia; risk estimates from epidemiologic studies

Outcomes reported

The review synthesised epidemiologic evidence from over 30 studies published since 2005 examining associations between drinking water nitrate exposure and cancer, reproductive outcomes, thyroid disease, and neural tube defects. Studies evaluated health endpoints including colorectal, bladder, and breast cancer, thyroid disease, and birth defects in relation to nitrate ingestion.

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