MONTREAL —

An aggressive cancer linked to asbestos is killing more Canadians than ever before, even decades after the end of a boom that saw buildings stuffed with the toxic substance.

The number of reported new cases annually of mesothelioma shot up 67 per cent over a decade and a half -- from 276 across the country to 461 -- according to the most recent federal figures.

Experts warn that the upward trend will continue for years as Canada feels the residual impact of its asbestos boom, and will likely be far worse in developing countries that still heavily use Canadian exports.

Most people diagnosed with mesothelioma have only six months to two years to live.

In British Columbia, deaths from asbestos-related diseases have increased as much as 69 per cent between 2002 and this year, according to the provincial workers' compensation board.

Over that same period in Quebec, where asbestos is still mined, the death rate climbed 39 per cent.

Mesothelioma, a cancer that is difficult to treat, is linked to past asbestos exposure in more than 80 per cent of cases.

It killed 32 per cent more Canadians in 2005 than in 2000, according to the most recent national figures available from Statistics Canada.

And these numbers may only tell part of the story, as many health experts believe the death toll could be much higher.

Hailed the "magic mineral" for its excellent insulating and fireproof properties, asbestos was widely used in Canada in the 1950s, '60s and '70s.

But studies linked the material to health risks, including cancer, and it was eventually labelled a hazardous substance.

Kathleen Ruff, the former director of the B.C. Human Rights Commission, says most Canadians mistakenly believe asbestos is a health issue from the past.

She cites the numbers as proof that it's more present than ever before.

"It's like landmines -- it goes on killing for decades and decades," she said in a phone interview from Smithers, B.C.

"We need to recognize that this is a major health crisis in Canada that's ongoing and still increasing (in) numbers every year."

The effects often strike retirees long after they've inhaled the sharp, needle-like asbestos fibres.

In many cases, victims never even know they've come into contact with it.

It usually takes up to 40 years for diseases linked to asbestos exposure -- such as mesothelioma, asbestiosis and other lung cancers -- to emerge.

Over several decades, the illnesses have remained dormant inside many unsuspecting Canadians.

And for many, the latency period is now expired.

"What you have now are people dying from asbestos-related diseases that were exposed anywhere from, say, 15 to 30 or 40 years ago," said Larry Stoffman, an occupational health expert with the United Food and Commercial Workers Union.

Stoffman expects the number of deaths across Canada to keep rising every year for the next five to 10 years -- until, finally, the number of cases reaches a plateau.

The long-term trend may be more severe in poorer countries.

In 2008, Canada's $100-million asbestos industry exported 175,000 tonnes of chrysotile -- almost all of it to developing nations. Some of the biggest importers include India, Indonesia, Sri Lanka and Bangladesh.

"They're going to have just huge problems going forward," Stoffman said.

Due to health risks, asbestos is no longer used in Canada, but one variety of the substance -- called chrysotile -- is still mined in Thetford Mines, Que.

Ottawa has spent about $20 million since the mid-1980s to promote asbestos use. It maintains that chrysotile is "less potent" than other types of asbestos and insists that it is not dangerous when precautions are taken.

But the World Health Organization estimates that asbestos, regardless of the type, causes 90,000 preventable deaths each year around the world.

"It's like mentholated cigarettes were good tobacco versus the bad ones," Stoffman said of claims that chrysotile asbestos is safe.

"It really just repeats the kind of almost pathetic promotion of a product that the tobacco industry's well known for."

There is little political appetite to discuss the issue in Canada.

The Bloc Quebecois and the Conservatives, which represent the riding that encompasses Thetford Mines, support the asbestos industry. While in decline, the industry still employs several hundred people.

The New Democrats oppose Canada's asbestos business and Liberal leader Michael Ignatieff earlier this year declared that the country should stop exporting the material.

That remark prompted a local Liberal candidate to resign.

"It's bizarre, (Quebec) is about the only place in the world, outside of maybe Kazakhstan and parts of Russia, where people actually think this stuff is OK," Stoffman said.

Within Canada, statistics from Quebec's workplace safety board show that asbestos-related diseases are the top occupational health hazard in the province.

Over the first seven months of 2009, illnesses related to asbestos exposure were responsible for 61 of the 104 reported occupational deaths in Quebec.

And the number of deaths tied to asbestos could be much higher.

An epidemiologist with Quebec's public health department says numerous cases are never reported because many workers suffering from these illnesses never bother to seek compensation from workplace safety associations.

Those suffering from mesothelioma, who often have only months to left to live, consider monetary compensation a low priority, said Louise De Guire.

She said miners aren't the only ones at risk of developing these diseases.

The number of cases affecting construction workers has increased while those in the mining sector have stabilized, she said.