Tar Sands Oil Development Is More Toxic Than Previously Thought, Study Finds

The Canadian government has likely underestimated the health risks of Alberta’s tar sands development, according to a new study.

The study, published Monday in the Proceedings of the National Academy of Sciences, focused on polycyclic aromatic hydrocarbons (PAH), persistent chemicals that are released during tar sands mining and processing and that have been associated with cancer in humans. Researchers compared the official records of PAH levels from the Athabasca Tar Sands Region to measurements from other scientific studies, and found that actual PAH emissions may be two to three times higher than recorded in environmental reviews.

The researchers discovered that, in previous estimates, the government had probably failed to account for the PAH emissions from evaporating tailing ponds, the toxic ponds that house the waste left over from the mining process, including water, sand, silt, clay, contaminants and leftover oil. Previous estimates also may not have taken into account dust from mining sites, which can contain levels of PAHs.

Though PAHs have been linked to to cancer in humans and birth defects and tumors in mice, the researchers said that their findings weren’t necessarily cause for alarm, because the levels of PAHs they recorded were comparable to those found in big cities, where people breathe in PAHs from sources like soot, cigarette smoke, vehicle exhaust and asphalt.


“It is not that I am raising the red flag here, that we should be very concerned, because we live with these concentrations day in and day out,” Frank Wania, co-author of the study, told the Globe and Mail. “All we are saying is that the basis for the human health risk assessment is flawed.”

But Jules M. Blais, a chemical and toxicology professor from the University of Ottawa who didn’t work on the study, told Climate Central that PAHs are “some of the worst things out there” and that the study’s findings have big implications for people who live along the proposed route of Keystone XL. Levels of PAH have already been found in the Athabasca River, and have increased between 1999 and 2009.

“From the standpoint of Keystone, the concerns are regarding potential breaches that could contaminate soils,” he said. “The same kinds of things that are getting into the Athabasca River could be relevant to Keystone.”

The study comes on the heels of a December report from Canadian government scientists that found levels of mercury around Alberta’s tar sands operations are up to 16 times higher than in other parts of the region. Tar sands development, the study said, has created a 7,300 square mile “bullseye” of mercury contamination around the development site, and elevated levels of mercury, a neurotoxin that’s been linked to brain damage, have been found in bird eggs in the region. In addition to the mercury and PAH pollution associated with tar sands development, tar sands oil contains 11 times more sulfur and nickel and six times more nitrogen than conventional crude oil, according to the Sierra Club.