Marie-Paule Spieser is one of 600 residents of Shannon, Que., who have signed a class-action lawsuit over water tainted with trichloroethylene, or TCE. (CBC)

The federal government denies responsibility for hundreds of cancer cases at the heart of a class-action lawsuit filed over allegations of contaminated water near CFB Valcartier in Quebec.

Residents of Shannon, outside Quebec City, are seeking more than $200 million in damages for health problems they say were caused by water tainted with an industrial solvent used on the military base in the 1950s.

The class-action lawsuit filed by about 600 residents alleges Shannon's water table was contaminated with trichloroethylene, or TCE, a substance Health Canada has said is a potential carcinogen.

In a statement of defence filed Friday in Quebec City, the federal government acknowledges a link between TCE and certain forms of cancer.

'They will answer to why they never, in the history of all this dumping, developed any way to protect the people of Shannon.'— Stephen Clarke, lawyer for residents

However, people living in Shannon were not exposed to high enough concentrations over a long enough period to become ill, the government says in the 70-page document.

Tests have revealed local wells were only affected by TCE during the 10 years of the 1990s, the statement of defence said. The scientific community did not predict until the 1980s that the TCE could have an impact on the quality of the groundwater, it said.

Plaintiffs welcome document

The statement of defence provides certain admissions that are helpful to the residents, said lawyer Stephen Clarke, one of the lawyers arguing the case.

"The fact that the government of Canada, after seven years, is admitting that there are cancers connected to TCE, is amazing to us," Clarke said. "They will answer to why they never, in the history of all this dumping, developed any way to protect the people of Shannon."

Clarke said he intends to prove there is evidence a dozen barrels of the toxic chemical were dumped near the base each month over a 20-year period.

"The exact year that it reached the town of Shannon, we feel we can establish within a degree of reasonable scientific certainty, would be the 1950s, or 60s," Clarke said.

Clark is hoping the case will be argued in the fall. The government, however, hopes to have the case thrown out, according to the statement of defence.

The document also describes how the Department of National Defence has spent $60 million to find the source of the problem and provide a clean source of drinking water to the people of Shannon.