Nitrates in mom's drinking water linked to birth defects in kids.

Jun 27, 2013

JD Brender, JD, PJ Weyer, PA Romitti, BP Mohanty, MU Shinde, AM Vuong, JR Sharkey, D Dwivedi, SA Horel, J Kantamneni, JC Huber Jr., Zheng, Q, MM Werler, KE Kelley, JS Griesenbeck, FB Zhan, PH Langlois, L Suarez, MA Canfield and the National Birth Defects Prevention Study. Prenatal nitrate intake from drinking water and selected birth defects in offspring of participants in the National Birth Defects Prevention Study. Environmental Health Perspectives. http://dx.doi.org/10.1289/ehp.1206249.

Synopsis by EHN Staff

Babies whose mothers consume nitrates in drinking water have a higher risk of spina bifida, cleft palate and other birth defects, according to a large study of children in Texas and Iowa. Used as fertilizers on crops, nitrates are one of the most widespread chemical contaminants in aquifers around the world. The study is the first to compare birth defects in kids to their mothers’ consumption of nitrates-tainted drinking water during pregnancy.

National Institutes of Health

Babies whose mothers consume nitrates in drinking water have a higher risk of spina bifida, cleft palate and other birth defects, according to a large study of children in Texas and Iowa. Used as fertilizers on crops, nitrates are one of the most widespread chemical contaminants in aquifers around the world.

The study is the first to compare birth defects in kids to their mothers’ consumption of nitrates-tainted drinking water during pregnancy. Previous epidemiological studies have linked prenatal exposure to birth defects. But those studies were based solely on the nitrate levels in the women’s drinking water. The new study evaluated the amounts and sources of the water consumed by the mothers.

Women whose babies were born with neural tube defects, limb deformities and oral cleft defects "were significantly more likely than control mothers to ingest 5 mg or more of nitrate per day from drinking water," wrote the researchers, whose study was published in Environmental Health Perspectives.

Mothers of babies with spina bifida, a disorder where the embryonic neural tube does not fully close, were twice as likely to ingest at least 5 milligrams of nitrate daily from drinking water than mothers in the control group. From one month preconception through the first trimester, mothers of children with limb deficiencies, cleft palate and cleft lip were, respectively, 1.8, 1.9 and 1.8 times more likely than control group mothers to ingest at least 5.42 milligrams of nitrate daily.

The federal standard for drinking water is 10 milligrams per liter for nitrate/nitrogen or 45 milligrams per liter for total nitrate.

In this study, the researchers studied 3,300 mothers from Iowa and Texas whose babies were born with neural tube defects, oral cleft, limb deficiency or congenital heart defects. They compared them to a control group of 1,121 mothers who lived in the study area and had babies without any major congenital malformations.

The mothers were questioned about their personal water use, including whether their water was private well water, unfiltered tap, filtered tap, bottled or other. Researchers asked about the quantity of water consumed at home and at work or at school on an average day. The researchers then estimated daily nitrate consumption.

Private well water contains the highest concentrations of nitrates. Estimated median levels in the study area for bottled water, public water supplies and private wells were 0.33, 5.0, and 17.6 mg/L, respectively.

Nitrate intake did not increase associations between the use of amine- and amide-containing drugs and birth defects. This is in contrast to a previous study linking these drugs to neural tube defects in Mexican-Americans.

Since nitrate contamination occurs in conjunction with other water contaminants, the researchers suggested that future studies of birth defects could look at prenatal exposure to mixtures of contaminants in drinking water.