Children, the environment and cancer

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Specific environmental contaminants - IV

Chlorinated water

Clean drinking water protects individuals from illnesses caused by bacteria and other microbes that can exist in untreated water. These illnesses include cholera, giardiasis (beaver fever) and sickness caused by the bacteria Escherichia coli (E.coli, which can cause diarrhea, abdominal cramps and sometimes more severe illness).

Chlorination has been in use for more than 100 years to disinfect water to make it suitable for drinking. It is a relatively inexpensive and easy to use.

For decades, researchers have studied the long-term effects of using chlorinated tap water and most have found a link between chlorinated water and an increased risk of cancer, particularly cancer of the bladder.

Health agencies and authorities should have guidelines about water chlorination that help ensure people receive as much benefit as possible from clean drinking water while reducing the health risks to the lowest possible level.

The risk of cancer from water chlorination is moderate when compared to the many health benefits of clean drinking water. However, many individuals are exposed to this risk and the level of risk may vary depending on where you live. It is important to ensure that safeguards are in place and that alternatives are used where possible.

Why we disinfect drinking water
Access to clean drinking water is essential for good health. Clean drinking water is virtually free of harmful microbes (microbes are organisms too small to be seen by the naked eye, such as bacteria, parasites and viruses). Drinking water disinfection has virtually eliminated waterborne diseases, making the water generally safe for human consumption.

Failing to treat water correctly can have disastrous results:

Not following updated national guidelines for water treatment could cause an outbreak of severe diarrhea.

Failing to follow the guidelines for operating wells could lead to an outbreak of the E. coli bacteria.

Ground water (water from underground wells) is generally free of harmful microbes since the earth acts as a natural filter. Municipal groundwater usually requires less complicated treatment than surface water before being delivered to homes, but still needs some disinfection while it is in the delivery system (from the treatment plant to your tap).

For most public water systems, it is important to disinfect water before it enters the water treatment facility and while it is in the facility (“primary disinfection”) and to maintain a safe level of disinfection throughout water delivery to homes and businesses (“secondary disinfection”). Disinfection throughout the delivery system is important to prevent small numbers of microbes from re-growing, and to kill or inactivate microbes that may enter the system during the distribution of water.

Chlorine kills or inactivates most harmful microbes and is an effective primary disinfectant. In addition, the effects of chlorination last throughout the water delivery system from the treatment facility to the tap in your home, making chlorine an effective secondary disinfectant as well.

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