| A Review of Nitrates in Drinking Water: Maternal Exposure and Adverse Reproductive and Developmental Outcomes Deana M. Manassaram, Lorraine C. Backer, and Deborah M. Moll Centers for Disease Control and Prevention, National Center for Environmental Health, Health Studies Branch, Atlanta, Georgia, USA 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. Key words: developmental outcomes, drinking water, groundwater, maternal exposure, nitrate, nitrite, private wells, reproductive health. Environ Health Perspect 114:320-327 (2006) . doi:10.1289/ehp.8407 available via http://dx.doi.org/ [Online 3 November 2005]
Address correspondence to D. Manassaram, CDC/NCEH/EHHE, Health Studies Branch, 4770 Buford Highway NE, MS F-46, Chamblee, GA 30341 USA. Telephone: (770) 488-3438. Fax: (770) 488-3450. E-mail: dmanassaram@cdc.gov The authors declare they have no competing financial interests. Received 16 June 2005 ; accepted 3 November 2005.
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