DDT in Dirt

Traces of the highly dangerous chemical DDT have been found in dirt on windows in Toronto, Hamilton and Ottawa, according to a study released in August.

The long-banned toxic contaminant was discovered in urban grime along with other PCBs (polychlorinated biphenyls) by the geography department at the University of Toronto.

"These toxins are moving through our systems and we want to find out what the effects are," says Miriam Diamond, associate professor of geography and lead author of the study. "These grimy layers trap more than what you would suspect,"

This discovery has widespread implications for the ecotoxicity of urban areas, says Diamond.

"Since the film and some of its contaminants are removed by the wind and the rain, humans and biota are exposed through the inhalation of air and the ingestion of urban soils and vegetation," she says.

"It would make me more cautious about growing vegetables downtown and ensuring that soils are relatively new and clean in children's playgrounds."

Rachel Carson's book Silent Spring exposed the dangers of DDT in 1962. It is found to impair the immunity of a child in the womb, cause cancer, tinker with the reproductive maturation of wildlife, emasculate alligators and give male fish the ability to give birth.

DDT has been banned in Canada since 1985. It is at the epicentre of a contentious argument between those that laud the chemical as an irreplaceable weapon against malaria, which affects 400 million people per annum, and those that say it tampers with the health of all nature.

Traces are still found in meat and dairy products because of illegal use, environmental persistence and importation of contaminated food. A recent study in Zimbabwe found traces of DDT in breast milk!

DDT is one of the Persistent Organic Pollutant's (POP's), also known as the "irty dozen," up for a worldwide ban by the UN treaty in December of this year. They can be found almost everywhere on the planet. In addition, because they spontaneously migrate towards the colder regions of the planet, these pollutants pose a critical threat to northern indigenous people, whose survival health and well-being depend on their traditional relationship with the ecosystem and the food it provides. Some of the most highly exposed populations are indigenous people living in polar regions far from major POPs sources. For example, the Inuit living in Baffin Island carry seven times as many contaminants in their bodies as people living in lower latitudes.