More than 6,280 tons of DDT were sprayed on the forests of New Brunswick, Canada to fight insect outbreaks in the 1950s and 1960s. Now, 50 years after the chemical was banned, scientists have discovered it lingering in the sediments of remote lakes at levels high enough to potentially alter entire aquatic food webs.
The research, published in the journal Environmental Science & Technology, collected samples from five lakes in New Brunswick in the spring of 2016, taking sediment cores dating as far back as 1890. Unsurprisingly, levels of DDT peaked in the 1960s and 1970s. But the team of Canadian scientists found that the uppermost layers of sediment — deposited in the last few years — still had levels of DDT and its toxic breakdown products well above 5 parts per billion, the limit for what is considered safe by the Canadian Council of Ministers of the Environment. On average, modern-day sediments in the lakes had levels 16 times higher than the safe limit; one lake measured 450 times the limit, Smithsonian reported.
“What was considered yesterday’s environmental crisis in the 1950s through [the]1970s remains today’s problem,” lead author Josh Kurek, an assistant professor in geography and the environment at Mount Allison University, said in a statement. “Decades of intense insecticide applications to our conifer forests have left a lasting mark on these lakes — and likely many others in eastern North America.”
Read more at: Yale Environment 360
A remote New Brunswick lake sampled for DDT. (Photo Credit: JOSH KUREK)