Health Effects of Chlorine in Drinking Water
The
U.S. General Accounting Office reports that there are serious deficiencies in
water treatment plants in 75% of the states. More than 120 million people (about
50% of the population) may get unsafe water according to a study conducted by
the Natural Resources Defense Council.
U.S.
Health Officials estimate 900,000 people each year become ill - and possibly 900
die - from waterborne disease. The General Accounting Office estimates 66% of
Safe Drinking Water Act violations aren’t reported.
The
contamination of water is directly related to the degree of contamination of our
environment. Rainwater flushes airborne pollution from the skies, and then
washes over the land before running into the, rivers, aquifers, and lakes that
supply our drinking water. Any and all chemicals generated by human activity can
and will find their way into water supplies.
The
chemical element chlorine is a corrosive, poisonous, greenish-yellow gas that
has a suffocating odor and is 2 1/2 times heavier than air. Chlorine belongs to
the group of elements called halogens. The halogens combine with metals to form
compounds called halides. Chlorine is manufactured commercially by running an
electric current through salt water. This process produces free chlorine,
hydrogen, and sodium hydroxide. Chlorine is changed to its liquid form by
compressing the gas, the resulting liquid is then
shipped. Liquid chlorine is mixed into drinking water and swimming pools to
destroy bacteria.
Until
recently, concerns about drinking water focused on eliminating pathogens. The
chlorine used to reduce the risk of infectious disease may account for a
substantial portion of the cancer risk associated with drinking water.
Chlorination of drinking water was a major factor in the reduction in the
mortality rates associated with waterborne pathogen. The use of chlorine was
believed to be safe. This view is evident in an article, which appeared on the
back page of the New York Times. The report stated that with the use of
chlorine, "Any municipal water supply can be made as pure as mountain spring
water. Chlorination destroys all animal and microbial life, leaving no trace of
itself afterwards". This statement reflected opinion accepted until recent years
when halogenated organic compounds, such as chloroform, were identified in
chlorinated drinking water supplies. Recent surveys show that these compounds
are common in water supplies throughout the
These
concerns about cancer risks associated with chemical contamination from
chlorination by-products have resulted in numerous epidemiological studies.
These studies generally support the notion that by-products of chlorination are
associated with increased cancer risks.
Chlorine is used to combat
microbial contamination, but it can react with organic matter in the water and
form dangerous, carcinogenic Trihalomethanes. According to Dr. Joseph M. Price,
MD, in Moseby's Medical Dictionary, "Chlorine is the greatest crippler and
killer of modern times. It is an insidious poison".
In a
1992 study that made front-page headlines, and was reported on in the July issue
of the American Journal of Public Health researchers at the Medical College of
Wisconsin in Milwaukee found that people who regularly drink tap water
containing high levels of chlorine by-products have a greater risk of developing
bladder and rectal cancers than people who drink unchlorinated water. The study
estimates that about 9 percent of all bladder cancer and 18 percent of all
rectal cancer cases are associated with long-term consumption of these
by-products. This amounts to over 20,000 new cases each year.
Morris, with epidemiologist
Thomas C. Chalmers and his colleagues at Harvard, used a new technique called
meta-analysis to combine the results from the 10 best studies, yielding the new
findings. They report that people drinking chlorinated water over long periods
have a 21% increase in the risk of contracting bladder cancer and a 38% increase
in the risk of rectal cancer. "I am quite convinced, based on this study, that
there is an association between cancer and chlorinated water.", says Robert D. Morris of the Medical College of Wisconsin
in
directed the new study.
About
90% of the population is drinking water which may contain hundreds of these
Disinfection By-products (DBPs), also known as Trihalomethanes. The
Environmental Protection Agency lowered the Maximum Contaminant Level for
Disinfection By-products but it will be years before the new standard goes into
effect.
In
his book, Coronaries/Cholesterol/Chlorine, Joseph M. Price, MD presents
startling evidence that Trihalomethanes, are the "prime
causative agents of arteriosclerosis and its inevitable result, the heart attack
or stroke." These Trihalomethanes are created when the chlorine that is added to
the municipal water supply reacts with organic matter such as leaves, twigs, or
chemicals from agricultural runoff.
Here's What The Experts Have
To Say:
"The
drinking of chlorinated water has finally been officially linked to an increased
incidence of colon cancer. An epidemiologist at Oak Ridge Associated
Universities completed a study of colon cancer victims and non-cancer patients
and concluded that the drinking of chlorinated water for 15 years or more was
conducive to a high rate of colon cancer."
Health Freedom News,
January/February 1987
"Long-term drinking of
chlorinated water appears to increase a person's risk of developing bladder
cancer as much as 80%," according to a study published in the Journal of the
National Cancer Institute. Some 45,000 Americans are diagnosed every year with
bladder cancer.
"Although concentrations of
these carcinogens are low...it is precisely these low levels which cancer
scientists believe are responsible for the majority of human cancers in the
"Chlorine itself is not
believed to be the problem. Scientists suspect that the actual cause of the
bladder cancers is a group of chemicals that form as result of reactions between
the chlorine and natural substances and pollutants in the water." (organic matter such as leaves and twigs.)
Greenpeace reports have found
chlorine-based compounds to be the most common toxic and persistent pollutants
in the
Summary and Prevention
Strategies
In
its proposal for revamping the Clean Water Act, the Environmental Protection
Agency has recommended examining chlorine's impact on health and the environment
(SN: 1/22/94, p.59). The agency's proposed $2 million, one-year chlorine study
would look at the effects of the use of chlorine and chlorine compounds in the
manufacture of paper, solvents, and plastics and in disinfecting waste water and
drinking water, says EPA' James F. Pendergast.
Contaminants may enter water
supplies at many points before reaching the tap. The carcinogens in drinking
water at the point of use may result from contamination of source water, arise
from the treatment processes, or enter as the water is transported to the
consumer. Varied carcinogens may contaminate the source water, but they usually
exist in drinking water at low concentrations. However, chemicals that enter
drinking water during water treatment are limited in
number,
but appear in drinking water
supplies with greater frequency than most source
water contaminants.
Under
conditions of average temperature, humidity, and activity, the human body loses
and, therefore, must replace about 2.3 liters of water each day. Two-thirds of
this consumption is in the form of water or some other beverage. Concerns about
the health risks or taste of drinking water may cause those who consume tap
water to shift to bottled water, or other beverages. These beverages may include
sweetened soft drinks and alcoholic beverages, which can pose health risks
greater than those associated with drinking water.
To
stop chlorination of drinking water to eliminate the elevated cancer risks from
chlorination by-products would be foolhardy. Nonetheless, the data provide
strong evidence to support expanded efforts in research and development of
alternatives to chlorination for the disinfection of drinking water.
Chlorination is particularly effective in preventing recontamination during
distribution. Alternatives must provide a similar level of protection. Perhaps
the most viable alternative is point of use water treatment units.
The
weight of the evidence suggests that chlorination by-products pose substantial
cancer risks that should be reduced.