Chlorinated Water Found to
Increase Risk of Bladder Cancer
by M.T. Whitney
Drinking, or even immersing yourself in, chlorinated water may
increase your risk of bladder cancer, says a new study.
The new study is the first to suggest that chlorine is harmful to humans
when ingested or absorbed through the skin, according to study leader
Cristina M. Villanueva of the Municipal Institute of Medical Research
in Barcelona and her colleagues.
Chlorine itself is not harmful, but its byproducts increase the risk
of cancer. Trihalomethanes are the most prevalent by-product, and they
can be absorbed into the body through the skin or by inhalation. When
THM is absorbed through the skin or into the lungs, they hold stronger
carcinogenic properties because they aren’t detoxified through the liver,
Villanueva and her team found in their research.
Villanueva and her team surveyed 1,219 individuals with bladder cancer
and 1,271 control individuals without the disease, polling them about
their exposure to chlorinated water, including their bathing, swimming
and tap water drinking habits.
The researchers also looked at the THM levels in the water systems of
123 municipalities.
People who live in households with more than 49 micrograms per liter
of THM were at double the risk of bladder cancer versus households that
have below 8 micrograms per liter of THM.
In industrialized countries, the common level is 50 micrograms per liter,
the researchers note.
The researchers also found that use of swimming pools increased the
risk by 57 percent and that people who drank chlorinated water held a
35 percent greater risk. Taking long showers and bathing also increases
the risk in households that has water with higher levels of THM.
In the United States, an estimated 67,160 new cases of bladder cancer
are expected to occur in 2007, and 13,750 deaths, according to statistics
from the American Cancer Society.
"If confirmed elsewhere, this observation has significant public
health implications in relation to preventing exposure to these water
contaminants," the researchers said in their report.
The study was published in the January issue of the American Journal
of Epidemiology.
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