Aerial view of the tailings pond at the Athabasca tar sands mines, 18 May 2012. Most ponds are coated in a sheen of oil that can be deadly to waterfowl, like ducks and geese, that land on its surface.

By Andy Coghlan
9 January 2013

Canada's push to exploit oil-rich sandy rock formations is certainly controversial, but does it pose a health threat? A first analysis has found an increase in carcinogens in sediment from lakes near to the Athabasca oil sands in Alberta but it is not yet clear if the pollution could make people ill.

John Smol of Queen's University in Kingston, Ontario, and colleagues analysed sediment cores from six lakes up to 90 kilometres north-west of Athabasca. They found that concentrations of polycyclic aromatic hydrocarbons (PAHs), well-known carcinogens, are between 2.5 and 23 times higher in the top layers of sediment than in layers laid down in 1960, at least 20 years before tar sand extraction began.

The type of PAHs has changed over that period too, from those typically generated by wood-burning to those originating from unburnt petroleum, suggesting tar sand excavation was the culprit. "We show clearly the timing of the change and the type of contamination, and the ones increasing are ones closely related to the tar sands industry," says Smol.

He says that this contradicts claims by the tar sands industry that the source of PAHs in lakes is natural. He suggests that the PAHs might get into lakes via vapour and smoke produced while extracting oil from the tar sands. [more]

Carcinogen levels soar in Canada's tar sand lakes



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