Public water treatment systems rely on chlorine to kill harmful bacteria. Until recently, concerns about drinking water focused on eliminating pathogens. Chlorination of drinking water was a major factor in the reduction in the mortality rates associated with waterborne pathogens. The use of chlorine was believed to be safe 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 North America. 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 risk of cancer and other health problems. These risks arise from both drinking and bathing in chlorinated water.
Following are quotes from a variety of sources:
SCIENTIFIC AMERICAN, Jan 18, 2007 “Drinking, bathing or swimming in chlorinated water may increase the risk of bladder cancer, a new study shows.” See article
U.S. COUNCIL ON ENVIRONMENTAL QUALITY: “Cancer rates for people on chlorinated water systems is 93% higher than for those on non-chlorinated water systems…”
DR. J.M. PRICE, MD: “Cancer risks among people drinking chlorinated water is 93% higher than among those whose water does not contain chlorine.”
NEW SCIENTIST 18 September 1986 – Ian Anderson “Studies indicates the suspect chemicals can also be inhaled and absorbed through the skin during showering and bathing.” “Ironically, even the chlorine widely used to disinfect water produces Carcinogenic traces.” “Though 7 out of 10 Americans drink chlorinated water, its safety over long term is uncertain.” “Drinking chlorinated water may as much as double the risk of Bladder Cancer, which strikes 40,000 people a year.”
U.S. NEWS &WORLD REPORT – July 29 1991 Is Your Water Safe–The Dangerous State of Your Water “A long hot shower can be dangerous. The toxic chemicals are inhaled in high concentrations.”
HEALTH CANADA –“Several studies on humans have also found a link between long-term exposure to high levels of chlorination by-products and a higher risk of cancer. For instance, a recent study showed an increased risk of bladder and possibly colon cancer in people who drank chlorinated water for 35 years or more.
High levels of THMs (trihalomethanes) may also have an effect on pregnancy. A California study found that pregnant women who drank large amounts of tap water with high THMs had an increased risk of miscarriage. These studies do not prove that there is a link between THMs and cancer or miscarriage. However, they do show the need for further research in this area to confirm potential health effects.”
CHLORINE AND YOUR SHOWER – Bruce Black “Taking long hot showers is a health risk, according to research presented last week in Anaheim California, at a meeting of the American Chemical Society–and to a lesser extent baths–lead to a greater exposure to toxic chemicals contained in water supplies than does drinking the water. The chemicals evaporate out of the water and are inhaled. They can also spread through the house and be inhaled by others. House holders can receive 6 to 100 times more of the chemical by breathing the air around showers and bath than they would by drinking the water”
BOTTOM LINE/August 87 – Dr. John Andelman, Ph.D.. “On one hand, chlorination has freed civilization form the constant dangers of waterborne epidemics. On the other hand in the mid–70’s scientists discovered that chlorination could create carcinogens in water.” “80% of the population drinks chlorinated water.” “There was a higher incidence of cancer of the esophagus, rectum, breast, and larynx and of Hodgkin’s Disease among those drinking chlorinated surface waters.” “Volatile organics can evaporate from water in a shower or bath.” “Conservative calculations indicate that inhalation exposure can be as significant as exposure from drinking the water, that is, one can be exposed to just as much by inhalation and/or dermal absorption.”
IS YOUR WATER SAFE TO DRINK? – Consumer Reports Books “Skin absorption of contaminant has been underestimated and ingestion may not constitute the sole or even primary route of exposure.
AMERICAN JOURNAL OF PUBLIC HEALTH – Dr. Halina Brown “Showering is suspected as the primary cause of elevated levels of chloroform in nearly every home because of the chlorine in the water.”
ENVIRONMENTAL PROTECTION AGENCY – Dr. Lance Wallace “A Professor of Water Chemistry at the University of Pittsburgh claims that exposure to vaporized chemicals in the water supplies through showering, bathing, and inhalation is 100 times greater than through drinking water.” “As chlorine is added to kill pathogenic microorganisms, the highly reactive chlorine combines with fatty acids and carbon fragments to form a variety of toxic compounds, which comprise about 30% of the chlorination by–products.” “During the mid-1970’s monitoring efforts began to identify widespread toxic contamination of the nation’s drinking water supplies, epidemiological studies began to suggest a link between ingestion of toxic chemicals in the water and elevated cancer mortality risks. Since those studies were completed a variety of additional studies have strengthened the statistical connection between consumption of toxins in water and elevated cancer risks. Moreover, this basic concern has been heightened by other research discoveries.
THE NADER REPORT – TROUBLED WATERS ON TAP – Center For Study of Responsive Law “The National Academy of Science estimate that 200 to 1000 people die in the United States each year from cancers caused by ingesting the contaminants in the water. The major health threat posed by these pollutants is far more likely to be from their inhalations as air pollutants. The reason that emissions are high is that because water droplets dispersed by the shower head have a larger surface–to–value ratio than water streaming into the bath.”
SCIENCE NEWS, VOL. 130 – Janet Raloff “The cause of atherosclerosis and resulting heart attacks and strokes is none other than the ubiquitous chlorine in our drinking water.”
CHEMISTRY AND CONTROL OF MODERN CHLORINATION – Dr. A.T. Palin, Ph.D..(O.B.E.) “Chlorine gas was despicably used during WWI. When the war was over, the use of chlorine was diverted to poisoning germs in our drinking water. All water supplies throughout the country were chlorinated. The combination of chlorine (when in drinking water) and animal fats results in atherosclerosis, heart attacks, and death.”
WATER CAN UNDERMINE YOUR HEALTH – Dr. N.W. Walker, D.S. “Chlorine is the greatest crippler and killer of modern times. While it prevented epidemics of one disease, it was creating another. Two decades ago, after the start of chlorinating our drinking water in 1904. The present epidemic of heart trouble, cancer and senility began.”
U.S. COUNCIL OF ENVIRONMENTAL QUALITY “Drinking tap water that is chlorinated is hazardous, if not deadly to your health.”
HEALTHY WATER FOR A LONGER LIFE – Dr. Martin Fox “Known carcinogens are found in drinking water as a direct consequences of the practice of chlorination. A long established public health practice for the disinfection of drinking water.”
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY – Francis T. Mayo, Director. “Chlorine is used almost universally in the treatment of public drinking water because of its toxic effect on harmful bacteria and other waterborne, disease-causing organisms. But there is a growing body of scientific evidence that shows that chlorine in drinking water may actually pose greater long term dangers than those for which it was used to eliminate.
These effects of chlorine may result from either ingestion or absorption through skin. Scientific studies have linked chlorine and chlorination by-products to cancer of the bladder, liver, rectum, and colon, as well as heart disease, atherosclerosis (hardening of the arteries), anemia, high blood pressure, and allergic reactions. There is also evidence that shows that chlorine can destroy protein in our body and cause adverse effects on skin and hair. The presence of chlorine in the water may also contribute to the formation of chloramines in the water, which can cause taste and odor problems.” “Since chlorine is required by public health regulations to be present in all public drinking water supplies, it is up to the individual to remove it at the point-of-use in the home.”
HEALTH FREEDOM NEWS, Jan./Feb. 1987 “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.”
St. PAUL DISPATCH & PIONEER PRESS, Dec. 17, 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. 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.)
WWW. waterwarning.com: “Chlorine was first added to a community water system in 1908 in Chicago and was instrumental in eliminating many types of water-borne disease such as Cholera and Typhoid fever. Prior to chlorination, many major cities had death tolls of 1 in 1000 people from Typhoid alone. Chlorine has been used to disinfect municipal water for over 80 years and has had some positive effects on public health. In the 1970’s it was discovered that chlorine when added to water, forms Trihalomethanes (chlorinated by-products) by combining with certain naturally occurring organic matter such as vegetation and algae. In 1992 the American Journal of Public Health published a report that showed a 15% to 35% increase in certain types of cancer for people who consume chlorinated water. This report also stated that much of these effects were due to showering in chlorinated water. The National Cancer Institute estimates cancer risks for people who consume chlorinated water to be 93% higher than for people who do not. The effects of drinking chlorinated water have been debated for decades. However, most experts now agree that there are some significant risks related to consuming chlorine and chlorinated by-products.”
CHLORINATED WATER CAN AFFECT CANCER RISK – Epidemiology 1998;9(1):21-28, 29-35. Lifetime consumption of chlorinated tap water can more than double the risk of bladder and rectal cancers in certain individuals, two new studies conclude. Both studies examined the lifetime water-consumption patterns, diets and lifestyles of over 2,200 middle-aged and elderly Iowans suffering from either bladder, colon, or rectal cancers. Those profiles were then compared with those of a pool of nearly 2,000 healthy ‘controls’.
Recent research has suggested that chlorine reacts with naturally-found organic compounds in water to form what the study authors call “chlorination byproducts.” They say many of these byproducts are “mutagenic and/or carcinogenic.” The first study found that smoking men who drank chlorinated tap water for more than 40 years faced double the risk of bladder cancer compared with smoking men who drank nonchlorinated water. Women who drank chlorinated water, on the other hand, had only slightly raised risks for bladder cancers, regardless of (their) smoking status.
The second study found that rates for rectal cancers for both sexes escalated with duration of consumption of chlorinated water. Individuals on low-fiber diets who also drank chlorinated water for over 40 years more than doubled their risk for rectal cancer, compared with lifetime drinkers of nonchlorinated water.
Similar differences were also found between the risk patterns of chlorinated-water drinkers who exercised at least once a week, and those who exercised just once a month, or less. Experts have long recommended regular exercise as one means of reducing one’s risk of rectal and other cancers. The study found no link between the long-term consumption of chlorinated tap water and the incidence of colon cancer. This was not surprising, the researchers explain, since colon tumors have very different patterns of genesis and development compared with rectal tumors. They speculate that the source of chlorinated tap water may help determine its potential to promote cancers. Since surface water (such as that found in lakes and reservoirs) usually contains higher concentrations of organic compounds, the study authors say it is also more likely to contain higher levels of (potentially carcinogenic) chlorination byproducts, compared with water sourced from deep underground.
Last updated: July 26, 2016