Even low arsenic levels in water tied to small, preterm babies

(Reuters Health) - Low levels of arsenic naturally found in drinking water in many U.S. states are associated with an increased risk of premature and underweight babies, a study in Ohio suggests.

Arsenic is one of the most common elements in the Earth’s crust and a natural contaminant in water in many regions of the world. While previous research has found high levels of arsenic in the water associated with a variety of birth complications in places like China, Argentina and Bangladesh, less is known about what happens to babies in places where pregnant women drink water with small amounts of arsenic.

For the current study, researchers examined data on 428,804 births in Ohio from 2006 to 2008 to see how birth outcomes differed based on county-level arsenic exposure in the water. Because up to 80 percent of homes in some counties had private well water - for which arsenic data wasn’t available - researchers restricted their analysis to counties where less than 10 percent or 20 percent of homes used well water.

In counties where less than 10 percent of the population used private wells, arsenic in public drinking water was associated with 14 percent higher odds of very low birth weight babies and 10 percent higher odds of premature deliveries, researchers report in Environmental Research.

“Arsenic contamination varies geographically, based on underlying geology,” said lead study author Kirsten Almberg, a public health researcher at the University of Illinois at Chicago.

“Testing your drinking water for a variety of contaminants including arsenic and lead is sound advice,” Almberg said by email.

The study found negative birth outcomes even when women lived in counties where tap water might expose them to arsenic levels below 10 micrograms per liter (10 ug/L), the maximum amount considered safe by the U.S. Environmental Protection Agency (EPA), Almberg noted. This suggests EPA regulations may not protect women from reproductive problems linked to arsenic, she said.

The study didn’t find an association between higher use of tap water at the county level and a risk of very premature infants or infants being small for their gestational age but not very low birth weight. Drinking water with arsenic did appear linked to a higher risk of low birth weight babies, but the added risk was too small to rule out the possibility that it was due to chance.

The study wasn’t a controlled experiment designed to prove whether or how specific levels of arsenic in drinking water might lead to negative birth outcomes.

Other limitations include incomplete or missing arsenic measurements for certain counties at certain points of time during the study, as well as the possibility that pregnant women drank water from sources that weren’t measured in the study.

“The disadvantage is that we don’t know exactly how much of the arsenic-tainted water the mothers were consuming, so the study simply assumes an overall average for each county,” said Philippe Grandjean, chair of environmental medicine at the University of Southern Denmark in Odense.

“This means that it is not possible to explore whether greater adverse effects were seen in births where the mother had consumed much public water, as compared with mothers who preferred bottled water,” Grandjean, who wasn’t involved in the study, said by email. “Overall, this imprecision means that the study probably underestimated the adverse effects, and that arsenic is more toxic to the baby than the authors calculated.”

Women who are worried about arsenic exposure during pregnancy should get their water tested if they use a private well, said Xindi Hu of the Harvard T.H. Chan School of Public Health in Boston. Municipal water supplies should already get routine testing.

They can also take a folate supplement because this can potentially reduce the toxicity of arsenic during pregnancy, Hu, who wasn’t involved in the study, said by email.

“I won’t suggest drinking only bottled water because it should be just a short-term emergency response, not a long-term solution,” Hu said. “What is even more severe, bottled water is not necessarily cleaner or safer than tap water.”

SOURCE: Environmental Research, online May 15, 2017.