CONCORD — Hundreds of cases of cancer could be avoided if more New Hampshire residents tested — and treated — their private wells, according to a new study.
Some 46 percent of N.H. households get their drinking water from a private well, according to Paul Susca, a supervisor in the Department of Environmental Services drinking water division. Ninety percent of those wells are bedrock wells, which is where the arsenic is found.
Maine and New Hampshire rank highest nationally in the percentage of residents who use private wells, he said.
About one in five — some 20 percent — of private wells in New Hampshire have elevated levels of arsenic, according to NHDES Commissioner Thomas Burack.
Arsenic is considered a Class 1 carcinogen. It's long been known that there's a high incident of arsenic in many private wells, particularly in Rockingham, Merrimack, Strafford and Hillsborough counties. As many as 41,000 people in those four counties alone may be drinking water with arsenic levels higher than the EPA standard, the study says.
But there's a problem just as significant as the arsenic levels — getting residents to have their well water tested and then doing something about it if arsenic or other contaminants are found. Although radon is even more commonly occurring, Susca said, this study only looked at arsenic.
Dartmouth College did the report for NHDES and the state Department of Health and Human Services. The reporters held focus group meetings with residents of four towns, including Londonderry, each with a high number of private wells, all in areas with relatively high arsenic levels and all with a high percentage of children.
The experts found many residents associated contaminants in water with taste, smell or appearance, none of which hold true for arsenic, radon and many other contaminants.
There appeared to be a significant lack of knowledge among residents about water testing standards, according to the report. Those who did have their water tested often stopped there, the study showed, either because the results were tough to interpret or because they thought the cost of treatment would be prohibitive.
But, Susca said, cost ought not to be a factor.
"In most cases, people can use a point-of-use, under-the-sink kind of system to treat arsenic at levels that commonly occur," he said. "It's not a hazard for skin exposure, it's the consumption, including cooking, so you only need to treat water you're consuming."
He said a typical under-the-sink system costs "hundred of dollars."
Officials don't have a firm grasp on the percentage of residents who use well water who have their water tested, Susca said, although a survey to get that number is underway.
Those conducting the study surveyed — or tried to — thousands of households with private wells. But the response rate was just about 3 percent.
Of those who did respond, 82 percent always or frequently drink tap water, according to the report.
The risk of consuming untreated well water with high levels or arsenic is significant. The study estimates of 688 cases of cancer among residents with arsenic-contaminated well water, 451 cases could be avoided if the water were treated for elevated arsenic levels.
Chronic arsenic exposure potentially leads to bladder and lung cancer. The state's rate of bladder cancer is the highest in the country at 29.7 cases per 100,000, according to the National Cancer Institute.
That statistic can't be entirely attributed to arsenic in well water, the study reports, but it's noteworthy that Maine ranks second for bladder cancer incidence and also has high levels of arsenic in its groundwater.
The study authors recommend improved communication about the importance of well water testing, testing events and campaigns in targeted towns as a next step.
"We want to emphasize that people should test their wells and do something about it if (arsenic) is at an elevated level," Susca said.
The NHDES is working to develop an online tool that would allow residents to plug in their test results and get recommendations for treatment. That's expected to roll out in the first half of 2015.
In the meantime, he said, people should have their water tested and if it needs treatment, consult several water treatment vendors.
There's a lot of information available at http://des.nh.gov/organization/divisions/water/dwgb/.