November 19, 1999
(Health and Community Services)

The following is being distributed on behalf of the Medical Officers of Health for the Province:

Information on Trihalomethanes (THMs) in public water supplies

In response to recent public attention to the issue of Trihalomethanes (THMs) in public water supplies, Medical Officers of Health for the Province wish to advise Newfoundlanders and Labradorians that there is no cause for alarm. THMs are a by-product of the combination of chlorine and organic material and are found in chlorinated water supplies. Some communities in this province have higher levels of THMs than the recommended level. However, the Department of Environment and Labour is working with these communities on reducing the level.

The following questions and answers may assist in allaying the concerns of residents. They were developed from information obtained from Health Canada's web site.

Should Newfoundlanders and Labradorians continue to chlorinate their drinking water?

Health Canada's evidence indicates that the benefits of chlorinating our drinking water - which yields a reduced incidence of water-borne diseases such as cholera and typhoid - are much greater than the risks of health effects from THMs. So, yes, people should continue to chlorinate their drinking water.

 

Should Newfoundlanders and Labradorians be concerned if the levels of THMs from their municipal water supplies are above the recommended level of 100 parts per billion (ppb)?

Health Canada says the results of most studies indicate that the length of time you are living in an area with high annual average levels is very important. It is also important to note that the 100 ppb level for THMs is based on an annual average. High levels on a particular day are not of concern unless they are consistently high resulting in high annual average. Typically, levels will be highest in the summer and lowest in the winter months.

 

Are there any steps that Newfoundlanders and Labradorians can take to remove chlorination by-products like THMs from their water?

The simplest method of reducing chlorination by-products is by putting water in a jug and letting it sit in the refrigerator overnight. By-products can also be reduced through boiling water or aerating drinking water in a blender. And, there are several types of water treatment devices that can be used in the home. Water filters that contain activated carbon are effective in removing some chlorination by-products from drinking water.

Should Newfoundlanders and Labradorians use bottled water instead of drinking water from the tap?

There is no reason to question the safety of bottled water currently in the marketplace. Nevertheless, there is also no firm evidence to suggest that bottled water is any safer than municipal tap water in Newfoundland and Labrador or Canada.

 

Does THM cause cancer?

THM is a cancer-causing agent. However, the risk of developing a rare cancer such as bladder cancer due to THM in drinking water is very small. People have a much higher risk of getting cancer if they smoke or have a poor diet.

 

Do THMs cause birth defects?

A November 1998 issue of Chronic Diseases in Canada, published by Health Canada's Laboratory Centre for Disease Control, concluded that there is insufficient evidence to say that chlorinated water by-products like THMs cause reproductive or birth defects.

 

If my public water supply has THMs, is it possible to become sick through showering?

According to Health Canada, epidemiological studies have demonstrated that ingestion of by-products like THM does not cause gastrointestinal problems. There is no information available on whether inhaling THMs could cause respiratory problems.

The public water supply in this province undergoes regular monitoring to ensure its safety for the people of Newfoundland and Labrador.

For further information, please contact the Health Canada Web site at:

//www.hc-sc.gc.ca/ehp/ehd/catalogue/general/iyh/chlorina.htm
and
//www.hc-sc.gc.ca/ehp/ehd/bch/water_quality/chlorinated_water.htm

1999 11 19 12:20 p.m.