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Study Finds Elevated Levels of Arsenic in Private Wells

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November 08, 2007

SURREY  – A groundwater quality investigation of selected private wells in the Langley-Surrey area has determined that arsenic concentrations in 44% of the 98 wells tested exceed the level set by the Guidelines for Canadian Drinking Water Quality, which is 0.010 milligrams of arsenic per litre of water (or 0.010 mg/L).

Fraser Health in conjunction with the BC Ministry of Environment commissioned the University of British Columbia to conduct a voluntary study of private wells in the Langley-Surrey area. The study was commissioned because elevated levels of arsenic had been detected in deep wells scattered between Cloverdale and the Trans Canada Highway area of the Lower Fraser Valley in previous testings.

The purpose of the study was to identify and characterize the concentration and distribution of arsenic in ground water in the area and to provide health protection public awareness of the issue. Although arsenic contamination of water can sometimes be associated with human activity, in this case, the source is naturally occurring.

Arsenic is introduced into water by the natural dissolution of arsenic found in the soil and bedrock. It is classified as a human carcinogen. Arsenic enters the body when it is swallowed in drinking water – arsenic in water is not appreciably absorbed through the skin when showering or bathing.

Short-term exposure to very high levels produces symptoms of what is commonly known as arsenic poisoning which is unlikely to occur at levels seen in this study. Long-term or lifetime exposure to arsenic in drinking water can have serious adverse health effects including several types of skin cancer and cancers of the lung, liver and bladder (see attached information sheet).

The Guidelines for Canadian Drinking Water Quality have set a Maximum Acceptable Concentration (MAC) of 0.010 milligrams per liter (mg/L) of arsenic in drinking water. This is equivalent to one teaspoon of arsenic in an Olympic-sized swimming pool. The MAC is based on the ability of treatment facilities and devices to reduce arsenic concentrations to 0.010 mg/L or less. However, long-term consumption of water with arsenic levels even lower than 0.010 mg/L has been associated with a small increase in cancer risk. For this reason, it is desirable to reduce arsenic levels in drinking water to the maximum extent practical.

Arsenic is found in ground water in many parts of Canada, and the levels measured in the current study are lower than have been found elsewhere in BC. Arsenic concentrations in the wells sampled in this study ranged from non-detectable to 0.071 mg/L. Wells with a depth greater than 150 feet (45 meters) generally had higher concentrations of arsenic and shallow wells had lower concentrations. When the study is completed a report will be available on the Fraser Health Authority website.

Arsenic in drinking water can be reduced through several treatment processes including reverse osmosis, some types of filters and distillation units. Boiling water does not remove arsenic and is not a treatment option in this situation.

Although the study was conducted in the Langley-Surrey area, based on previous experience with well water quality, Fraser Health recommends that all private well owners have their drinking water tested on a regular basis, usually every two to three years. A general chemical analysis should be requested, including arsenic testing.

Testing of private wells is the responsibility of the well owners. If arsenic is found to be present, a water treatment company should be consulted for advice on the best option of removing this contaminant.

For media inquiries, please contact:

Fraser Health Media Pager | 604-450-7881

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