Chlorine in
Drinking Water
Disinfectants
Many water suppliers add a disinfectant to drinking water to kill
germs such as giardia and e coli. Especially after heavy rainstorms, your water system may add
more disinfectant to guarantee that these germs are killed.
Chlorine Bleach: When boiling is not practical, chemical
disinfection should be used. Common household bleach contains a chlorine
compound that will disinfect water. The procedure to be followed is
usually written on the label. When the necessary procedure is not given,
find the percentage of available chlorine on the label and use the
information in the following tabulation as a guide.
|
Available Chlorine |
Drops per Quart of Clear Water |
|
1% |
10 |
|
4-6% |
2 |
|
7-10% |
1 |
(If strength is unknown, add ten drops per quart of water. Double
amount of chlorine for cloudy or colored water or water that is extremely
cold.)
The treated water should be mixed thoroughly and allowed to stand,
preferably covered, for 30 minutes. The water should have a slight
chlorine odor; if not, repeat the dosage and allow the water to stand for
an additional 15 minutes. If the treated water has too strong a chlorine
taste, it can be made more pleasing by allowing the water to stand exposed
to the air for a few hours or by pouring it from one clean container to
another several times.
Chlorine Tablets. Chlorine tablets containing the necessary
dosage for drinking water disinfection can be purchased in a commercially
prepared form. These tablets are available from drug and sporting goods
stores and should be used as stated in the instructions. When instructions
are not available, use one tablet for each quart of water to be purified.
Health Effects
Chlorine. Some people who use drinking water containing chlorine
well in excess of EPA's standard could experience irritating effects to
their eyes and nose. Some people who drink water containing chlorine well
in excess of EPA's standard could experience stomach discomfort.
-----------------------
Reference:
"Disinfection of
Drinking Water," Ground Water & Drinking Water. U.S.Environmental Protectin Agency.
July 2, 2004.
<http://www.epa.gov/safewater/faq/emerg.html.Emergency>.
"Drinking Water
Contaminants," Ground Water & Drinking Water. U.S. Environmental
Protection Agency. July 2, 2004.
<http://www.epa.gov/safewater/hfacts.html>.
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 United States.
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 Milwaukee, who 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 artherosclerosis 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. St. Paul Dispatch
& Pioneer Press, December 17, 1987
"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 United States." Report Issued By The
Environmental Defense Fund
"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.)
St. Paul Dispatch & Pioneer Press, December 17, 1987
Greenpeace reports have found chlorine-based compounds to be the most
common toxic and persistent pollutants in the Great Lakes
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.
--------------------------
Reference:
"Health Effects of Chlorine in Drinking Water,"
July 2, 2004.
<http://www.lehigh.edu/~inenviro/waterstuff/chlrine2.htm>.
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