A study conducted by researchers from the Dartmouth Superfund Research Program on Toxic Metals has revealed that consuming water containing arsenic at levels currently deemed safe by the EPA (10 ppb) causes adverse health effects in pregnant/lactating mice and their offspring. The researchers found that ingesting arsenic in drinking water at low concentrations (10 ppb) disrupted lipid metabolism in pregnant and lactating mothers, resulting in a reduction of nutrients in the blood and breast milk. Consequently, their suckling young showed significant signs of stunted growth and development during the postnatal phase of development before weaning. However, litter size and gestation period were not adversely affected.

“The pups were essentially malnourished; they were small and underdeveloped,” says Joshua Hamilton, coordinator of the study and co-author of the research paper, which was published in the scientific journal PLoS ONE (May 31, 2012). When the pups were fed milk from a mother who had not been exposed to arsenic in her drinking water, their growth rates improved, however, only the male pups fully caught up with developing young mice that had not been exposed to arsenic.

The Chemically Sensitive Young

According to Hamilton, offspring are particularly sensitive to environmental chemical contaminants because “they are developing rapidly. It's not hard for very low doses of a chemical to have big effects on a developing animal.” The study showed that mothers who ingested arsenic with their drinking water had concentrations of triglyceride in their blood and breast milk that were significantly lower than normal, indicating a disruption in the metabolism and storage of fat in their systems.

“Normally, the body is very good at storing fat and glucose for later use”, explains Hamilton. “Up to a certain point, if a mother is malnourished during and after pregnancy, the offspring will not be compromised, because her body uses nutrients it has stored to nourish the baby. Her body will basically 'eat itself' to provide for the baby.” But, because mothers exposed to arsenic have this protective mechanism disrupted, they are unable to provide the necessary nutrients to the pups through the breast milk. The arsenic compromised mothers also exhibited a condition referred to as hepatic steatosis, more commonly known as 'fatty liver', where fat accumulates in the liver abnormally.

The pups from mothers exposed to arsenic showed significantly stunted growth just ten days after birth, and at day 21, when they are typically weaned, they were still far too small to be removed from their mothers.

The EPA recently reduced the Maximum Contaminant Level safety standard for arsenic in public drinking water supplies to 10 ppb, which it considers 'safe' for long-term exposure over a lifetime. However, many unregulated drinking water sources from private wells, many of which are situated in areas that are known to have high naturally occurring geological concentrations of arsenic, have concentrations exceeding 100 ppb.

Should 'Safe' Arsenic Levels be Adjusted?

“This study raises a couple of issues. First, we have to think again about whether 10 ppb arsenic as a U.S. drinking water standard is safe and protective of human health,” says Hamilton, who is a chief academic and scientific officer at the Marine Biological Laboratory (MBL) and a senior scientist in the MBL Bay Paul Center.

“Second, this study reiterates an emerging idea in toxicology that pregnant women and their offspring are uniquely sensitive to chemicals in their environment. There is a special window of vulnerability for both of them”, explains Hamilton. “Third, if you are on a private water system, particularly in a region with high arsenic, have your water tested so that you know what you are drinking.”

Public water suppliers publish freely available records of levels of regulated chemicals, including arsenic, in drinking water. If you are concerned about levels of arsenic in drinking water from a private well, you can request the Department of Environmental Protection or similar local agency to test a water sample for you to determine concentrations of arsenic or other chemical contaminants. If arsenic levels are high, the best solution for those accessing drinking water from private wells is to purchase bottled water or a water filter that will remove arsenic from the water. A Big Berkey water filter fitted with arsenic water filters in the lower filter chamber will remove arsenic from drinking water to make it safe to drink. The black berkeys that come standard with every system also remove fluoride from the drinking water.

Be Aware of Your Arsenic Intake!

“The message here is: Pay attention to your total arsenic exposure, both in drinking water and also in food.” stressed Hamilton. “Pregnant women, especially, need to be very careful and protective of their health. Environmental chemicals such as arsenic, along with tobacco, alcohol, drugs—all of these chemicals are potential stressors to pregnant women and their offspring.”

“The research conducted by Dr. Hamilton and Dr. Kozul-Horvath is an important component of our Superfund Research Program (SRP) at Dartmouth,” says Bruce Stanton, Dartmouth SRP Director. “These significant results add to the body of knowledge we are developing pertaining to the sources of arsenic, its effects at the cellular level, the ways in which it affects the health of mammals like mice and ultimately, how it causes disease and harmful health outcomes for humans.”

For more information on arsenic in general as well as arsenic in private well water visit the Dartmouth Toxic Metals web site.

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