Pesticide contamination of surface waters in Canada

Photo Credit: David Stanley Photo Credit: David Stanley

A new study published in the Bulletin of Environmental Contamination and Toxicology sought to determine the extent to which surface waters in Southern Ontario were contaminated with carbamate pesticides and metalaxyl. Carbamates are a class of pesticides commonly used in agriculture and household products to control pests. Scientists sampled surface waters from ten different sites in Southern Ontario for pesticide contamination between 2007 and 2010. They found that the pesticides carbaryl, metalaxyl and pirimicarb were most frequently detected, and in 2008 were detected in more than 50% of all water samples. Carbaryl exceeded the Canadian Water Quality Guideline to protect aquatic life in three samples, and was detected in higher concentrations during rainfall events due to runoff. Metalaxyl, on the other, had most likely contaminated waterways through drift or overspray.