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Study downplays WTC dust danger

Workers spent weeks in the dust at Ground Zero.
Workers spent weeks in the dust at Ground Zero.

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NEW YORK (CNN) -- A study of dust collected around the World Trade Center site immediately after the September 11 attacks found that the particles were less dangerous than previously feared, a co-author of the study told CNN.

The study found that most of the cancer-causing particles found in dust on surfaces were big enough to be expelled from the lungs in coughing, co-author Dr. Paul Lioy said in a phone interview.

However, long-term exposure to the dust and exposure to large fiberglass particles found at the site could pose health hazards, Lioy said.

People exposed to the dust should see a doctor if they haven't already, said Peter Montague, co-founder and director of the Environmental Research Foundation who reviewed but did not participate in the study.

The findings are to be published in the February issue of Environmental Science & Technology, a journal published by the American Chemical Society, an independent scientific group not sponsored by the chemical industry.

An earlier report on the study found the toxic chemicals in the air but had not yet determined the size or degree of hazard posed by the particles, Montague said. The study was conducted by eight scientists from universities in the New York City region.

The group took samples from 13 locations around the Trade Center site from September 12 to September 17, 2001. The first report analyzed the composition of dust and smoke. The second report measured the size of particles by forcing them through a filter after sieving them and suspending them in air.

The potential cancer-causing agents include polychlorinated biphenyls, or PCBs, and polycyclic aromatic hydrocarbons, or PAHs, the study said.

The dust containing these chemicals came from the "pulverized building and construction materials including cement, cellulose and glass fibers," the study said.

While most larger particles can be coughed up, very small particles are more dangerous because they can become lodged in the lungs for years, Lioy said.

Montague expressed concern that the study could be misinterpreted to mean that the public has nothing to worry about.

"I think the study was fine," Montague told CNN in a phone interview. "They [the scientists] clearly know what they are doing. My concerns are the conclusions drawn from the study."

People should not forget that the study did find significant amounts of hazardous materials such as fiberglass, Montague said.

"The conclusion that it's all good news is, to me, not the full story," he said.

Lioy agreed, saying the study's findings apply more to people exposed to dust for short periods, not necessarily to firefighters and others who were exposed for long periods of times.

"We've got to learn to define these things much more clearly for people," Lioy said. "We don't want to promote confusion."

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