Low to moderate levels of arsenic in New England well water may be responsible for an increased risk of bladder cancer in that region, suggests a new study.
"It's an important disease to be concerned about," said senior author Debra Silverman, of the National Cancer Institute in Bethesda, Maryland. "If people are drinking from these wells, I think it's important for people to get their water tested."
Silverman and her colleagues write in the Journal of the National Cancer Institute that bladder cancer death rates have been elevated in New England compared to the rest of the country for the last five decades. Bladder cancer diagnoses were also found to be about 20 percent higher in New England.
Thanks to the area's geography, private wells there tend to contain low-to-moderate levels of arsenic from bedrock. Until the 1950s, pesticides containing arsenic were used extensively in the region, too.
"In studies coming from Chile, Taiwan and Argentina where people were drinking water with high levels of arsenic, they had increased levels of bladder cancer mortality," Silverman told Reuters Health.
More recent research, including some from New Hampshire, found that even low levels of arsenic exposure may increase bladder cancer risk.
About 77,000 new cases of bladder cancer will be diagnosed in the U.S. during 2016, experts expect, and about 16,400 people will die of it.
For the new study, the researchers compared 1,213 people who were diagnosed with bladder cancer between 2001 and 2004 in Maine, Vermont and New Hampshire to 1,418 people without cancer.
In addition to looking at what else may have put the people at risk for bladder cancer, the researchers also estimated how much water participants had consumed on a daily basis over the course of their lives, and the water's arsenic content.
The current arsenic limit for safe drinking water is below 10 micrograms per liter. Arsenic levels in these New England states are thought to be below 100 micrograms per liter.
Overall, the researchers found that bladder cancer risk increased with how much water people drank.
Among those with private wells, people who drank the most water were nearly twice as likely to have bladder cancer as those who drank the least.
The strongest association was for so-called dug wells that are less than 50 feet deep, particularly when those shallow wells were in use since the days when arsenic-containing pesticides were common.
While the new study can't prove arsenic in the well water caused the increase in bladder cancer diagnoses and deaths in New England, Silverman believes it's the likely culprit.
People should be aware that arsenic does affect private drinking water supplies in New England, and everyone should test for that, said Joseph Ayotte, one of Silverman's coauthors and a hydrologist at the U.S. Geological Survey in Pembroke, New Hampshire.
He said people in New Hampshire can see arsenic concentrations in special maps (PDF): http://on.doi.gov/1T284hX.
"Those show clearly where the problem is the biggest and can be used as a guide for people to understand the potential risk for having arsenic in their wells," said Ayotte. "But the recommendation is that everybody tests."
People can ask the state or private companies to analyze their well water for a fee. Then, he said, different types of water filters are available to lower arsenic levels.