David Schindler, a water scientist at the University of Alberta, says there's no longer any doubt the oilsands are adding toxic compounds to the Athabasca River. (CBC)

A study of water quality at 60 sites along the Athabasca River and its tributaries makes it clear the oilsands have added cancer-causing toxins to the environment, a scientist at the University of Alberta says.

The highest levels of polycyclic aromatic compounds [PACs], which are known to contain carcinogens, were found within 50 kilometres of two major oilsands upgraders, David Schindler said Monday.

"We wanted to test the hypothesis that all of this is coming from natural sources, which is what we hear from industry all the time," Schindler said of the study conducted in the winter and summer of 2008.

"We found PACs in parts per trillion, but they are toxic at parts per trillion."

At those levels, fish eggs and embryos can be damaged, which could explain the abnormalities reported by fishermen downstream, he said.

Airborne pollution was a surprise

Schindler said it was no surprise that industry had an impact on the river water, but was surprised at the amount of airborne pollution.

"It was quite a big cloud — we could track it chemically out to around 50 kilometres from the sources," he said. "We think, just based on the signature, that it's in part dust blowing off the surfaces of these big, expanses of mines.

"I hate to speculate about the consequences for humans downstream, but it's not as though industry isn't putting these things in the river, they clearly are."

Schindler called for human health studies, especially on breast milk, to establish the levels of toxins present in people who live in the area.

He also called for Environment Canada to get more involved in the research.

"They have the best expertise in the country in that line, but every time there's a budget problem they get their funds cut, so they monitor one site on that river," Schindler said.

'Consistent with natural sources': province

The province disputes the study's conclusions.

"The concentrations that are identified in this paper, and all of the monitoring that we have done, are very, very low for these PACs, well below any effects guideline and consistent with natural sources, erosion of natural outcroppings," said Preston McEachern, a water scientist with Alberta Environment.

The province has been monitoring the same sites with the same kind of equipment for almost a year, McEachern said, and found nothing to cause alarm.

"If the public is getting the perception that we're not doing enhanced monitoring and research around the oil sands as this industry has grown, that's absolutely incorrect," he said.