Engineering professor Mark Borsuk and the Dartmouth Toxic Metals Superfund Research Program received a $93,000 grant from the New Hampshire Department of Environmental Services to explore the reasons many state residents who obtain their water from private wells do not test for arsenic.

Geisel School of Medicine professor Bruce Stanton, a member of the research program, said the program has just received an additional $13 million grant to further its work.

About 40 percent of the state’s 1.3 million residents obtain their drinking water from private wells, which do not require regulation, and around 20 percent of these wells have arsenic levels higher than the Environmental Protection Agency’s safety standard.

The program investigates how hazardous substances, like arsenic and mercury, impact human health.

The study hypothesizes that renters and new state residents are less likely to test their water because they are less likely to know about the risks of arsenic exposure, or may have a lack of knowledge about what to do if arsenic is found. Around 4,000 postcards will be sent to households across the state over the next week, and any private well user may participate in an online survey.

Borsuk said areas with the highest levels of arsenic exposure, including counties in the southern part of the state, have geographic features that make exposure more likely, such as aquifers close to bedrock. Some wells in these areas have reported arsenic concentrations as high as 300 parts per billion. The EPA standard safety level for arsenic in drinking water is 10 parts per billion, Stanton said, and even this low amount can have adverse health effects.

Courtney Carignan, a postdoctoral researcher in epidemiology, said Dartmouth uses a public water system that regulates arsenic levels.

A recent study showed that exposure to arsenic at five parts per billion resulted in a diminished IQ score of about five points in children and infants, Stanton said. His own research, which focuses on arsenic’s effect on immune response, indicates that very low levels of arsenic can impair the lungs’ ability to fight bacterial infections.

Carignan said her research explores the effects of arsenic exposure on infants who receive formula versus breast milk, noting that formula mixed with untested well water can contain higher arsenic levels.

Stanton said it is possible to educate people about these adverse effects and have them monitor their water.

“The real problem is getting people to recognize that there is a problem,” Stanton said.

Borsuk said that while the EPA regulates public water, it is unable to regulate private well water. As a result, the responsibility for ensuring water safety for private wells falls on owners, who may have the water sampled and tested by state or private laboratories.