Thames Centre officials say they are adjusting their day-to-day operations in order to reduce excess levels of haloacetic acids found in the drinking water, according to the director of public works for the municipality just east of London, Ontario.
Since January 2020, Ontario municipalities have been required to notify local public health units when the haloacetic acid (HAA) concentration exceeds 80 micrograms per litre, or 80 parts per billion. Based on testing done four times a year, the most recent rolling annual average haloacetic acid concentration for Thames Centre’s drinking water was 82.6 micrograms per litre.
“We are actively seeking alternatives to reduce the disinfection byproduct precursors in the treatment process at the Water Treatment Facility,” announced Jarrod Craven, director of public works with the Municipality of Thames Centre, in a statement.
Thames officials explained that chlorination has long been used to eliminate pathogenic organisms from drinking water systems and has led to the virtual elimination of waterborne disease. However, haloacetic acids can form when the chlorine compounds used in the disinfection process react with naturally occurring organic material present in the water. The health benefits associated with the chlorination of drinking water, officials added, far outweigh the potential risks associated with slightly elevated levels of haloacetic acid within the drinking water system.
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Dr. Alex Summers, Medical Officer of Health with the Middlesex-London Health Unit, said the slightly elevated haloacetic acid levels “do not constitute an immediate health risk,” and alerting the public about the findings is about maintaining transparency.
“Given the many risk factors we are exposed to every day, this situation would not lead to an increase in an individual’s overall risk of developing cancer,” stated Summers.
The threshold levels are set through Ontario’s Drinking Water Quality Standards. When the new reporting level came into effect, the province also suggested the following remedies, in addition to Thames’ plan of reducing disinfection byproduct precursors: Reducing the chlorine dose or changing the disinfectant (e.g., to ozone, chlorine dioxide, UV); optimizing the amount of time chlorine is in contact with water to reduce reaction time but still maintain primary disinfection (CT); or reducing water age in the distribution system (e.g., by managing storage levels or using auto-flushers).
According to Health Canada, the haloacetic acids most commonly found in drinking water are monochloroacetic acid (MCA), dichloroacetic acid (DCA), trichloroacetic acid (TCA), monobromoacetic acid (MBA) and dibromoacetic acid (DBA).
The Federal-Provincial-Territorial Committee on Drinking Water also recommends that every effort be made not only to meet the guideline, but to maintain concentrations of haloacetic acids as low as reasonably achievable.
In 2019, the Attawapiskat First Nation in the Kenora district of northwestern Ontario declared a state of emergency over elevated levels of trihalomethanes and haloacetic acid.