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Your Environment. Your Health.

Prenatal Nitrate Exposure and Birth Defects

Jean Brender, Ph.D.
Texas A&M Health Sciences University
NIEHS Grant R01ES015634

With support from NIEHS, a large population-based, case-control study revealed that prenatal exposure to nitrate from drinking water was associated with certain birth defects. However, higher nitrate intake did not increase associations between prenatal nitrosatable drug use and birth defects, suggesting that endogenous formation of nitrosatable compounds might not be the underlying mechanism for the birth defects.

The researchers used data from the National Birth Defects Prevention Study to link addresses of 3,300 case mothers and 1,121 control mothers in Iowa and Texas to public water supplies and nitrate measurements. Mothers of babies with spina bifida were twice as likely [95 percent confidence interval (CI): 1.3, 3.2] to ingest ≥ 5 mg nitrate daily from drinking water than control mothers, who consumed less than less than 0.91 mg of nitrate daily. From one month before conception through the first trimester, mothers of babies with limb deficiency were 1.8 more likely than control mothers to ingest ≥ 5.42 mg of nitrate daily (95 percent CI: 1.1, 3.1). The results for cleft palate and cleft lip for this time period were similar, with mothers 1.9 (95 percent CI: 1.2, 3.1), and 1.8 (95 percent CI: 1.1, 3.1) times more likely to ingest the high levels of nitrate, respectively. The researchers concluded that future studies of birth defects could focus on prenatal exposure to mixtures of contaminants in drinking water since nitrate contamination occurs with other water contaminants.

Citation: Brender JD, Weyer PJ, Romitti PA, Mohanty BP, Shinde MU, Vuong AM, Sharkey JR, Dwivedi D, Horel SA, Kantamneni J, Huber JC, Zheng Q, Werler MM, Kelley KE, Griesenbeck JS, Zhan FB, Langlois PH, Suarez L, Canfield MA. 2013. Prenatal nitrate intake from drinking water and selected birth defects in offspring of participants in the national birth defects prevention study. Environ Health Perspect 121(9):1083-1089.

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