DDT lingers in Canada lakes 50 years after chemical banned: study

OTTAWA: The potent insecticide DDT still lingers in Canadian lakes nearly 50 years after it was banned, according to a study published Wednesday that highlighted its harmful impact on micro-organisms at the bottom of the local food web.

From 1952 to 1968, planes sprayed more than 6,280 tons of dichlorodiphenyltrichloroethane or DDT on forests in the Atlantic coast province of New Brunswick to control pest outbreaks in commercial forests, according to Environment Canada.

It was arguably one of the largest aerial spray programs in North America. Public awareness of DDT’s harmful effects on wildlife and the environment eventually led to curtailed use of the insecticide until it was banned in 1972. But researchers led by Joshua Kurek at Mount Allison University in New Brunswick recently found traces in lake sediments that “still exceeded levels considered safe for aquatic organisms,” they said in a statement. They also identified a potential risk of the DDT spreading across the local food web, beyond the lakes’ shores. “We believe that the potential for direct transfer of DDT from the aquatic to terrestrial ecosystem exists given the DDT legacy in NB,” the researchers concluded in the study. Their findings were published in the American Chemical Society (ACS)’s Environmental Science and Technology publication.