Arsenic
in drinking water from private wells may explain the elevated bladder cancer
risk among people in three New England states, a new study suggests.
Bladder cancer rates in Maine, New Hampshire and Vermont have been about 20 percent higher than the national rate for more than 50 years, the researchers noted.
They said this difference was not explained by factors such as smoking or job
exposures.
"Arsenic is an established cause of bladder cancer, largely based on
observations from earlier studies in highly exposed populations," said
senior study author Debra Silverman. She is chief of the Occupational and
Environmental Epidemiology Branch of the U.S. National Cancer Institute.
"However, emerging evidence suggests that low to moderate levels of
exposure may also increase risk," she added in an institute news release.
Many people in these states have private wells, which are not maintained by
municipalities and are not subject to federal regulations, the researchers
said.
These wells may contain arsenic, typically at low to moderate levels. Previous
research has shown that drinking water with high levels of arsenic increases
the risk of bladder cancer, the study team said.
Possible sources of arsenic in the wells include natural release from rock deep
in the ground and pesticides widely used on crops between the 1920s and 1950s,
according to the study.
For the study, the researchers compared more than 1,200 newly diagnosed bladder
cancer patients with more than 1,400 people without bladder cancer who lived in
the same areas.
Participants provided information about known and suspected bladder cancer risk
factors, such as smoking, occupation, ancestry, use of wood-burning stoves, and
diet.
"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," Silverman said.
"This suggests that neither risk factor explains the excess occurrence of
bladder cancer in northern New England."
Bladder cancer rates in Maine, New Hampshire and Vermont have been about 20 percent higher than the national rate for more than 50 years, the researchers noted.
They said this difference was not explained by factors such as smoking or job
exposures.
"Arsenic is an established cause of bladder cancer, largely based on
observations from earlier studies in highly exposed populations," said
senior study author Debra Silverman. She is chief of the Occupational and
Environmental Epidemiology Branch of the U.S. National Cancer Institute.
The researchers can't establish a direct cause-and-effect relationship, but
they found that people who drank the most water from private wells had twice
the risk of bladder cancer as those who drank the least.
This association was stronger among those who drank from dug wells, which are
less than 50-feet deep and at greater risk for contamination, they said.
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