Increased risk of bladder cancer in New England may be partly due to drinking water from private wells, particularly dug wells established during the first half of the 20th century, according to researchers from the National Cancer Institute. Bladder cancer mortality rates have been elevated in northern New England for at least 5 decades. Incidence rates in Maine, New Hampshire, and Vermont are about 20% higher than in the United States overall, researchers said in a press release.
To explore reasons for the elevated risk, NCI investigators and colleagues in New England compared well water consumption, smoking, occupation, ancestry, use of wood-burning stoves, and consumption of various foods for 1,213 people in New England who were newly diagnosed with bladder cancer, and 1,418 people without bladder cancer who were matched by geographic area.
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The amount of arsenic ingested through drinking water was estimated based on current levels and historical information. Increasing cumulative exposure was associated with an increasing risk of bladder cancer. Among people who used private wells, people who drank the most water had twice the risk of those who drank the least. Highest risk was seen among those who drank water from dug wells established before 1960, when the use of arsenic-based pesticides was common.
“Arsenic is an established cause of bladder cancer, largely based on observations from earlier studies in highly exposed populations,” said Debra Silverman, Sc.D., chief of the Occupational and Environmental Epidemiology Branch of the NCI, Rockville, Md., and senior author on the study. “However, emerging evidence suggests that low to moderate levels of exposure may also increase risk,” she said in the press release.
“Although smoking and employment in high-risk occupations both showed their expected associations with bladder cancer risk in this population, they were similar to those found in other populations,” Dr. Silverman said. “This suggests that neither risk factor explains the excess occurrence of bladder cancer in northern New England.”
These study results indicate historical consumption of water from private wells, particularly dug wells in an era when arsenic-based pesticides were widely used, may have contributed to the excess rate in New England residents, Dr. Silverman and colleagues concluded.
The study was published in the Journal of the National Cancer Institute (2016;108[9]:djw099).
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