Marie-Paule Spieser is one of the 600 residents of Shannon who have signed a class action lawsuit over tainted water. (CBC) Montreal researchers have found a link between cancer rates in the town of Shannon, Que., and exposure to a chemical that was dumped into the community's lagoons decades ago.

For years, people living in the community north of Quebec City have watched an unusually high number of residents fall ill with cancer.

Many have suspected the cases were connected to the discovery of trichloroethylene (TCE) in the community's water table.

TCE is a powerful chemical degreaser once used in abundance at the neighbouring Valcartier military base.

The federal government has not made the link between the chemical and the cases of cancer. However, in 2000, government officials told people to stop drinking from their taps.

Now researchers participating in a lawsuit launched by residents in Shannon have found through DNA testing a common pattern in the cancerous tissue of patients exposed to TCE, a pattern not seen in other cancerous tissues.

'We have a population of maybe 4,000 ... and actually I have 12 cancers of the brain. It's at least 12 times more than it should be.'—Claude Juneau, researcher

Researcher Claude Juneau, who used to work at the Valcartier base, said there are 240 cases of cancer in Shannon to date.

"Here in Shannon we have a population of maybe 4,000 … and actually I have 12 cancers of the brain. It's at least 12 times more than it should be," said Juneau.

Juneau is involved in a class action lawsuit launched by 600 Shannon residents against the federal government and SNC Lavalin.

Wells in some neighbourhoods contained up to 180 times the level of TCE considered acceptable by Health Canada.

The neighbourhoods now use a different water supply. Ottawa has paid to build a new water system for the community.

Investigation reveals details about what Ottawa knew

A Radio-Canada investigation to be aired Thursday night on the program Enquête shows the federal government knew decades ago that TCE was harmful to the environment.

Federal officials are not commenting because the matter is before the courts.

Shannon Mayor Clive Kiley said the new research and the investigation strengthen the case for compensation for people who may have become sick.

"There's just no other explanation as to why we can have so many cancers," he said.