Canadian study says U.S. overstates asbestos threat

BOSTON (CNN) -- A Canadian study concludes that the U.S. Environmental Protection Agency is greatly overestimating the risk of lung cancer from small amounts of asbestos, but a U.S. doctor disagrees with the study.

Studies have shown asbestos, which was one of the most popular building insulation materials for several decades, is dangerous. Breathing asbestos fibers can cause a variety of lung diseases, but lung cancer is thought to be the greatest hazard. The risks have been documented in asbestos workers who breathe in large amounts of the fiber.

Far less certain is how much risk arises from exposure to much lower amounts, such as the fibers that are stirred up by deterioration of asbestos insulation around pipes.

Dr. Michael Camus and others at the University of Quebec assessed the risk of lung cancer in women who lived in asbestos mining towns in Quebec in a study published in Thursday's New England Journal of Medicine.

They found 2,242 deaths among women who lived in the towns between 1970 and 1989 and compared them with women living in 60 other places in Quebec.

Asbestos worker

Only about 5 percent of the women in the mining towns worked in the asbestos industry. Most of their exposure was from breathing outside air or from asbestos brought home by their husbands on their clothes.

Based on the amount of asbestos the women breathed, the formula developed by the EPA predicts their risk of lung cancer would be twice as high as usual. But the Canadian study found they were no more likely than women living elsewhere to die from lung cancer.

The study's authors say the EPA's formula overestimates the risk of asbestos-induced lung cancer by at least tenfold.

Dr. Philip J. Landrigan of Mount Sinai School of Medicine in New York City disagrees in an editorial accompanying the Canadian study.

He says the women in the Quebec mining towns were exposed to asbestos particles that were larger than those that occur after asbestos is processed for industrial use and that those larger particles are less likely to get into the lungs and cause cancer.

"By contrast, in buildings in this country we're dealing with asbestos insulation where the asbestos has been milled, refined and reduced to a very fine particle size," Landrigan said. "So to compare the women in Quebec with children in schools in this country is like comparing apples to oranges."

Landrigan said he believes the EPA formula is correct because it is intended to estimate the hazard of fine asbestos particles commonly used in commercial products.

Asbestos removal continues in schools, homes and other buildings across the United States, and Landrigan says the millions of dollars spent removing the material is not being wasted.

"When asbestos is encountered in a building, it must be taken very seriously," he said.

Related stories:

• Reno: Homeless, others exploited in hazardous jobs - April 24, 1998
• Supreme Court to hear appeal by ex-asbestos makers - November 1, 1996

Related sites:

• Welcome to the Asbestos Institute
• U.S. Environmental Protection Agency
  • The Asbestos Informer
• Occupational Safety & Health Administration
  • Asbestos

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