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SPOKANE, Wash. - Researchers have embarked on an ambitious study to track the health of thousands of high school graduates over a half century in a Montana town where a toxic mine has killed hundreds of people and made it the deadliest Superfund site in the nation.

People who attended Libby High between 1950 and 1999 and then moved away are being asked to submit to tests to help determine the extent of contamination caused by asbestos mining and processing in the northwestern Montana town. Researchers will track down many of the 13,000-plus graduates with the help of the school district and alumni groups, and then ask them to undergo a battery of X-rays, CT scans and pulmonary function tests.

Dr. Stephen M. Levin of the Mount Sinai School of Medicine in New York said the study is part of a larger range of work trying to figure out why asbestos-related disease coming out of Libby appears to be particularly fast-moving and virulent.

"This progresses much more rapidly than your grandfather's asbestos-related disease," Levin said.

The mineral vermiculite was mined in Libby for much of the past century. At the mine's peak in the l970s, operator W.R. Grace produced almost 2 million tons of ore annually and employed about 200 miners and others. Vermiculite was shipped around the world to make insulation.

But unmarketable material — much of it asbestos — made up about 80 per cent of the ore. The crushing of the rock in the course of the vermiculite mining set billions of asbestos fibers loose in clouds of dust that drifted 9.6 kilometres down to Libby. Many residents of the town of 3,000 who never set foot in the mine were exposed, and kids once frolicked in polluted piles of fluffy white waste dumped behind the community baseball field.

A recent Associated Press examination of the toxic legacy of Libby found that the pollution has killed more than 400 people while revealing that the federal government has been overwhelmed in its response to the catastrophe.

The Environmental Protection Agency only last year declared a health emergency in the town, nearly a decade after saying it would take about two years to clean up the mess at a cost of US$5.6 million. Ten years on, the price tag has exceeded $333 million as asbestos keeps showing up in schools, businesses and houses. Environmental workers in haz-mat suits are still working in people's yards.

The findings of the study could be important in helping the federal government understand what it's up against as it attempts to clean up the pollution.

The study was announced this week and will begin later in June. As part of the research, subjects must have spent the majority of their high school years in Libby between 1950 and 1999 and then moved away without coming back in their adult years to live or work.

Lungs develop until a child reaches about age 18, so looking at the lungs of people who left town about that age and did not live there again can show how much damage occurs in childhood as compared to adulthood, Levin said. Scientists believe asbestos exposure in childhood is more dangerous because lungs are still developing, he said.

The research will also compare exposure of Libby asbestos to that of more common commercial forms and examine the presence of autoimmune disorders like lupus in people exposed to asbestos. The Center for Asbestos Related Disease is performing the $4.8 million epidemiology study.

Scientists will also examine quirks that sometimes show up in asbestos exposure. For example, a person who suffered only a secondary exposure to asbestos in Libby might see disease develop more quickly than a construction worker who worked directly with asbestos, and researchers hope the study will explain why the Libby asbestos is so aggressive.

To evaluate that, researchers will be comparing infected people in Libby with records of building trades workers who installed insulation in New York City, Levin said.

"We are sort of the petri dish of asbestos here in Libby," said Gayla Benefield, a member of the Class of 1961 who has spent the past two decades advocating for local residents.

Libby is a small town and many of the people who used to live here keep in touch with friends they left behind.

"It's a unique situation to have a group of people with a high degree of exposure to a toxin and to be able to bring them back," said Kimberly Rowse, clinical coordinator at the center. "They are willing to engage because this is their hometown."

The Agency for Toxic Substances and Disease Registry, a branch of the federal Centers for Disease Control and Prevention, is funding the project.