The state Department of Environmental Services is recommending that all private well owners in New Hampshire test their water for contaminates after a study published Monday by the National Cancer Institute (NCI) revealed a possible link between bladder cancer and private wells that contain dangerous levels of arsenic.

"To explore possible reasons for the excess incidence of bladder cancer in northern New England, NCI conducted a large study in Maine, New Hampshire and Vermont," DES said in a press release. "The team of researchers, including New Hampshire Department of Health and Human Services (DHHS) and the Geisel School of Medicine at Dartmouth, examined the role of known and suspected bladder cancer risk factors, with a focus on private well water consumption and arsenic levels in drinking water."

The study, authored by Dr. Debra Silverman, chief of the Occupational and Environmental Epidemiology branch of the NCI, showed an association between exposure to low-to-moderate amounts of arsenic and bladder cancer risk.

"Heavy consumption of drinking water from private dug wells, which are shallow – less than 50 feet deep – and potentially susceptible to contamination from manmade sources, may have contributed to the longstanding bladder cancer excess in northern New England," Silverman said. "We observed this relationship particularly for dug wells established prior to 1960, a time when arsenic-based pesticides were widely in use."

Silverman’s assertion that older wells are more susceptible to contamination is especially poignant, considering that the cancers associated with arsenic contamination occur at higher rates in New England than they do in the rest of the country – a problem that has been observed for over 50 years.

"Bladder cancer mortality rates have been elevated in northern New England for over half a century," NCI said in a press release. "The incidence of bladder cancer in Maine, New Hampshire, and Vermont has been about 20 percent higher than that in the United States overall. Rates are elevated among both men and women. A unique feature of this region is the high proportion of the population using private wells for their drinking water."

NCI’s study comes following a 2014 report by Dartmouth College to DES and DHHS that showed hundreds of terminal cancer cases in the Granite State could have been avoided if well owners had been made aware of water contamination through testing. Professor Mark Borsuk, of the Thayer School of Engineering, project leader for the Dartmouth study, said that number may seem high, but it is unfortunately accurate.

"We believe our estimate based on the currently available information is more likely to underestimate health effects in New Hampshire than overestimate them," he noted in 2014. "Over the last 25 years, the number of diseases associated with arsenic has increased, the parts of the body affected by arsenic-mediated diseases have increased, and estimates of what constitutes a safe long-term arsenic dose have decreased."

DES recommends that all private well users have testing conducted by an "accredited laboratory." Once testing is complete, residents can interpret their results using the state’s "Be Well Informed" website and if necessary should seek help from a water treatment professional.

For more information on the "Be Well Informed" program, visit http://des.nh.gov/organization/divisions/water/dwgb/well_testing/index.htm

Matthew Medsger can be reached at 594-6531, mmedsger@nashuatelegraph.com or @Telegraph_MattM.