Researchers at the University of Toronto used computer models to assess the plausibility of reported emissions of a group of atmospheric pollutants known as polycyclic aromatic hydrocarbons, many of which are highly carcinogenic.
"When dealing with chemicals that have the potential to harm people and animals, it is vital that we have a good understanding of how, and how much they are entering the environment," study author Abha Parajulee said in a university release Tuesday.
Environmental Impact Assessments have so far only considered the PAHs that are released directly into the atmosphere, the researchers noted, and the risk associated with those direct releases have been judged to fall within acceptable regulatory limits.
However, the researchers' model took into account other indirect pathways for the release of PAHs that hadn't been assessed before or were deemed negligible.
In one case, they reported, they found evaporation from tailings ponds -- lakes of polluted water created through oil sands processing -- may actually introduce more PAHs into the atmosphere than direct emissions.
"Tailings ponds are not the end of the journey for many of the pollutants they contain," Parajulee said. "Some PAHs are volatile, meaning they escape into the air much more than many people think."
Their findings suggest better monitoring data and emissions information are needed, the researchers said.
"Our study implies that PAH concentrations in air, water, and food, that are estimated as part of environmental impact assessments of oil sands mining operations are very likely too low," Toronto environmental chemistry Professor Frank Wania said. "Therefore the potential risks to humans and wildlife may also have been underestimated."