=======================Electronic Edition========================
RACHEL’S HAZARDOUS WASTE NEWS #84
—July 4, 1988—
News and resources for environmental justice.
——
Environmental Research Foundation
P.O. Box 5036, Annapolis, MD 21403
Fax (410) 263-8944; Internet: erf@igc.apc.org
==========
The Back issues and Index are available
here.
The official RACHEL archive is here.
It’s updated constantly.
To subscribe, send E-mail to rachel-weekly-
request@world.std.com
with the single word SUBSCRIBE in the message. It’s free.
===Previous issue==========================================Next issue===
CHLORINE CHEMICALS IN OUR WATER LINKED TO HUMAN BLADDER CANCER.
In 1908, Americans starting adding chlorine to drinking water to
kill bacteria and viruses that cause serious diseases like
typhoid, cholera, polio and hepatitis. In the U.S. today, all
public water from surface sources (rivers, streams and lakes) is
chlorinated.
Chlorine is a highly reactive chemical, which is one reason why
it makes such a good disinfectant even in parts-per-million
concentrations. However, in addition to killing germs, chlorine
reacts with organic substances found naturally in drinking water
(humic acids, for example), and causes the formation of a class
of chemical compounds called trihalomethanes (or THMs). Some
trihalomethanes have long, obscure names like
bromodichloromethane (a carcinogen in rodents),
dibromochloromethane, dichloroethylene, and dichloroethane, but
some are better known, such as chloroform, benzene, carbon
tetrachloride, and toluene, all of which are known or suspected
carcinogens.
In 1974 Robert Harris, a scientist then working for the
Environmental Defense Fund (a traditional environmental group)
published a report showing a statistical link between
cancer-causing substances in drinking water and cancer incidence
among humans in New Orleans, LA. When Harris’s report hit the
newspapers, it created an uproar. Harris was pilloried, as
Rachel Carson had been 12 years earlier for publishing Silent
Spring. The water suppliers of America, municipal officials, and
many Right Thinking public health scientists went berserk.
“Absurd!” they said. “Hair-brained!” “Probably a communist!”
According to the conventional wisdom, chlorinating water was good
for people, not bad, and it was “irresponsible” to suggest
otherwise.
There are people today who still believe Dr. Harris was wrong,
just as there are people who believe there is no connection
between smoking and illness. The Tobacco Institute, for example,
still insists tobacco is harmless, and the American Cancer
Society, for example, does not even list chemicals in our
drinking water as a cause of cancer.
Between 1974 and today, at least 18 studies have appeared in the
literature linking carcinogens in drinking water to human
cancers. Now a massive new study has been reported in the JOURNAL
OF THE NATIONAL CANCER INSTITUTE, based on analysis of the water
consumption habits of 2805 white men and women who have bladder
cancer, compared to 5258 white men and women (matched for age,
sex, and geographic area) who do not have bladder cancer. The
study drew subjects from 10 geographical regions: Atlanta,
Detroit, New Orleans, San Francisco, and Seattle, plus the states
of Connecticut, Iowa, New Jersey, New Mexico and Utah.
Trained interviewers administered a standardized questionnaire to
subjects (and controls) in their homes. Questionnaire items
elicited a life history including lifetime use of artificial
sweeteners and tobacco products, coffee consumption, use of hair
dyes, a lifetime occupational history, and a history of relevant
medical conditions.
In a separate survey, trained data collectors analyzed records
from, and conducted interviews with managers at 1102 water
companies in the 10 geographical areas the study covers (plus New
York City and Chicago, because so many subjects had lived in
those places at one time or another). Water samples were also
collected from every water supplier, and analyzed for
trihalomethanes.
People use tap water for coffee, tea, reconstituted juice, soup,
and plain drinking water, as well as for cooking. (Beer and soft
drinks are customarily deionized and charcoal filtered, removing
most chlorine byproducts and other contaminants.) The average
water intake among men in the study was 2 liters per person per
day, 1.4 liters of it from tap water. Women drank, on average,
1.7 liters of water per day, 1.35 liters of it from tap water.
The study revealed that those who drank 8 cups of chlorinated tap
water for 40 to 59 years had a 40% greater risk of bladder cancer
than those who drank less tap water or who drank unchlorinated
water. People who drank the most tap water for 60 years had an
80% greater risk of bladder cancer.
The effect was most pronounced among non-smokers. The
researchers speculated that the effect of smoking (which does
cause bladder cancer, as well as lung cancer and several other
cancers) overwhelmed the effect of chlorinated water among
smokers. Among non-smokers who drank chlorinated water for 60
years, the risk of bladder cancer was increased 310%.
The authors of the report emphasized that cigarette smoking and
occupational exposure to carcinogens are the main causes of
bladder cancer. Bladder cancer is diagnosed in 33,000 men and
12,400 women in the U.S. each year. Among men, 70% of this is
caused by cigarette smoking and occupational exposure, the
authors believe, and among women 40% comes from these causes.
Still trihalomethanes in drinking water appear to be a
significant contributor to the nation’s total bladder cancer
problem. Among the subjects in the present study, 12% of the
bladder cancer (336 cases) could be explained by chlorinated
water, the authors calculate. Among nonsmokers, 27% of the
bladder cancers are explained by chlorinated water.
Dr. Harris and many other scientists have said for a long time
that we should consider changing our method of disinfecting
drinking water. Europeans do not chlorinate their water because
they do not like the taste it gives to the water; instead, they
bubble ozone through their water, which kills germs but does not
affect the taste. It also does not create cancercausing
trihalomethanes.
Two conclusions: Chlorinating our drinking water solves some
problems but creates others. We should switch to ozone
treatment, abandoning chlorine. Second, this study gives powerful
new evidence that chlorinated chemicals cause human cancers.
Their industrial use should be reduced.
For a free copy of this important study, contact Dr. Kenneth
Cantor, Landow Building, Room 3C08, National Institutes of
Health, Bethesda, MD 20892; phone (301) 496-1691. Ask for a
reprint of “Bladder Cancer, Drinking Water Source, and Tap Water
Consumption: A Case-Control Study,” JOURNAL OF THE NATIONAL
CANCER INSTITUTE, Vol. 79, No. 6 (Dec., 1987), pgs. 1269-1279.
Footnotes 8 through 25 provide citations to 18 separate studies
linking trihalomethanes to various cancers. Your local librarian
can help you track down copies of the 18 studies.
–Peter Montague, Ph.D.
Descriptor terms: chlorination; chlorine; water; drinking water;
cancer; bladder cancer; risk assessment; ozone; thms;
carcinogens; robert harris; edf; la; rachel carson; tobacco; acs;
american cancer society; ga; mi; la; ca; wa; ct; ia; nj; nm; ut;
opinion surveys; health; health statistics; studies; findings;