Nitrate Health Risk Assessments Riddled with Methodological Errors, Study Warns

Safe and clean water is a fundamental requirement for human health and well-being, and both the quantity and quality of drinking water directly affect the health of populations. That makes the investigation of waterborne contaminants and the risks they pose a matter of growing scientific and public concern. Among the many contaminants found in drinking water, nitrate stands out for its importance: it is a recalcitrant compound, meaning it persists stubbornly in the environment, and it is present in most water bodies. It originates from both natural sources and human activities, most notably agriculture and the discharge of wastewater.

Numerous studies over the years have attempted to quantify the health risks that nitrate exposure poses to different age groups, including infants, children, and adults. But according to a team of researchers writing in the journal Environmental Geochemistry and Health, the reliability of many of these estimates is in question.

In a discussion paper led by Mahsa Maleki and colleagues, with Mina Aghaei among the authors, the researchers report that a review of the literature revealed recurring methodological inconsistencies that may compromise the reliability of nitrate risk estimates. Rather than presenting new measurements of exposure or new health outcomes, the paper examines how the assessments themselves are being carried out, and where the standard playbook is being misapplied.

The first major problem the authors identify concerns the nitrate reference dose, abbreviated RfD. The paper finds that RfD values for nitrate are being misapplied across different population groups.

The second issue involves inconsistencies in chemical units and nomenclature. The authors highlight these unit and naming inconsistencies as a recurring source of error in the published literature.

The third source of uncertainty arises from the conversion of nitrate to nitrite during exposure and risk assessment. Risk assessments that attempt to account for this conversion introduce additional uncertainty, and the paper examines how that uncertainty is, or is not, being handled in published work.

To make these problems concrete, the authors draw on examples from published research, using them to illustrate and critically analyse the common methodological pitfalls they have identified. The discussion-paper format is deliberate: rather than reporting a single new dataset, the article synthesises patterns of error observed across many studies, in the hope that future assessments will avoid them.

Nitrate is among the most widespread contaminants of water resources globally, driven by agricultural runoff and wastewater discharge alongside natural sources. The authors frame their contribution as a call for greater methodological rigour and consistency in how nitrate health risk assessments are constructed, reported, and interpreted.

Subject of Research: Methodological inconsistencies in human health risk assessment of nitrate exposure in drinking water

Article Title: Methodological challenges and uncertainties in human health risk assessment of nitrate exposure

Article References: Maleki, M., Janjani, H., Hadi, M., Yunesian, M., & Aghaei, M. (2026). Methodological challenges and uncertainties in human health risk assessment of nitrate exposure. Environmental Geochemistry and Health, 48(16), Article 656. https://doi.org/10.1007/s10653-026-03524-x

Image Credits: AI Generated

DOI: 10.1007/s10653-026-03524-x

Keywords: nitrate, drinking water, health risk assessment, reference dose, nitrite, water contamination, methodology, exposure assessment, public health, environmental geochemistry, Methodological, challenges