A Review of Nitrates in Drinking Water: Maternal Exposure and Adverse Reproductive and Developmental Outcomes

Abstract

In this review we present an update on maternal exposure to nitrates in drinking water in relation to possible adverse reproductive and developmental effects, and also discuss nitrates in drinking water in the United States. The current standard for nitrates in drinking water is based on retrospective studies and approximates a level that protects infants from methemoglobinemia, but no safety factor is built into the standard. The current standard applies only to public water systems. Drinking water source was related to nitrate exposure (i.e., private systems water was more likely than community system water to have nitrate levels above the maximum contaminant limit). Animal studies have found adverse reproductive effects resulting from higher doses of nitrate or nitrite. The epidemiologic evidence of a direct exposure–response relationship between drinking water nitrate level and adverse reproductive effect is still not clear. However, some reports have suggested an association between exposure to nitrates in drinking water and spontaneous abortions, intrauterine growth restriction, and various birth defects. Uncertainties in epidemiologic studies include the lack of individual exposure assessment that would rule out confounding of the exposure with some other cause. Nitrates may be just one of the contaminants in drinking water contributing to adverse outcomes. We conclude that the current literature does not provide sufficient evidence of a causal relationship between exposure to nitrates in drinking water and adverse reproductive effects. Future studies incorporating individual exposure assessment about users of private wells—the population most at risk—should be considered.

Evaluation of Shallow Groundwater Contamination and Associated Human Health Risk in an Alluvial Plain Impacted by Agricultural and Industrial Activities, Mid-west China

“…There has already been a lot of literatures reporting drinking water nitrate pollution and its adverse effects on human health, but the causal relationship between exposure to nitrates in drinking water and adverse reproductive effects is still not clear (Manassaram et al 2006). However, the health risk assessment studies can provide useful information for water-quality management to ensure the general safety of drinking water for people.…”

A study of adverse birth outcomes and agricultural land use practices in Missouri

“…There is some evidence from epidemiologic studies that exposure to nitrate from drinking water sources may increase the incidence of neural tube defects, oral cleft defects, limb deficiencies (Brender et al, 2004;Brender et al, 2013), cardiac defects (Cedergren et al, 2002), SGA and spontaneous abortions (Manassaram et al, 2006). Animal studies also show moderate associations with fetal loss, neonatal mortality, and decreased litters and live births (Manassaram et al, 2006).…”

Impact of intensive agricultural practices on drinking water quality in the EVROS Region (NE GREECE) by GIS analysis

“…Nitrate levels, in particular, must be strictly regulated. Several epidemiological studies have shown a significant risk probability between elevated nitrate concentrations in drinking water and a battery of pathological states ranging from reproductive anomalies and human cancer, to endemic nephropathy and methemoglobinaemia (De Roos et al 2003;Fewtrell 2004;Manassaram et al 2006;Niagolova et al 2005). These findings, thus, highlight the need for more sustainable methods of production.…”