Posted on 07/26/2004 8:24:45 PM PDT by neverdem
After the World Trade Center collapsed, air samples collected nearby showed that levels of some cancer-causing chemicals had soared but had fallen so quickly that the pollution spike was unlikely to increase cancer risks in nearby communities, researchers reported yesterday.
The chemicals, called polycyclic aromatic hydrocarbons, are often found in sooty particles generated when fire consumes anything from tobacco to jet fuel. They have been linked to lung, skin and bladder cancers as well as other health problems.
Earlier studies had estimated that between 100 and 1,000 tons of the chemicals spewed into the air after the attacks, both from the smoldering fires and from the exhausts of diesel-powered construction vehicles that flooded into the area.
But this is the first study to track trends in these chemicals in samples of the most harmful particles of sooty pollution, those smaller than 2.5 microns across.
Motes that minuscule can travel deep into the lungs and enter the bloodstream. Larger particles tend to drop out of the air quickly and also are expelled from the lungs by coughing and other defenses.
The researchers found that P.A.H. concentrations in the samples captured shortly after the attacks soared to some 65 times the average levels measured in city air, and the types detected tended to be those most likely to come from a source like burning wreckage.
Within 100 days, however, those chemicals were largely gone, as were the fires. From then until spring 2002, the samples contained declining amounts of the varieties associated with diesel exhaust, the researchers said, and by May of that year returned to amounts typical for New York City air.
At least for these hydrocarbons, the duration of potential exposure was so short, compared with a typical lifetime, that "cancers from these chemicals is not something to worry about," said Dr. Stephen M. Rappaport, an author of the study and professor of environmental health at the University of North Carolina.
The study, published yesterday in The Proceedings of the National Academy of Sciences, was conducted by scientists at the university and the National Exposure Research Laboratory of the Environmental Protection Agency, in Research Triangle Park, N.C. The paper can be found online at pnas.org.
Dr. Rappaport cautioned that the analysis had involved only polycyclic aromatic hydrocarbons and not the many other potentially harmful substances, including asbestos, that drifted in the wind after 9/11.
While cancer rates are unlikely to rise as a result of the exposure, the paper said, other effects, including harm to fetuses, could not be ruled out.
The paper also said that workers toiling in the smoldering rubble could easily have inhaled air with much higher concentrations of the hydrocarbons. The samples were collected at three sites around the perimeter of ground zero, and on the 16th floor of 290 Broadway, where Environmental Protection Agency offices are located.
But generally, according to the researchers and some pollution experts not associated with the study, the findings should provide at least a bit of relief to residents of the area, many of whom have remained worried about the effects that pollution from the disaster could have on their health.
"There should be some reassurance here for the general public," said Dr. Jonathan M. Samet, the chairman of the department of epidemiology at Johns Hopkins University's Bloomberg School of Public Health. But he quickly added that cancer was only one of many health problems that could result from pollution spawned after the attacks.
Dr. Frederica P. Perera, the director of the Columbia Center for Children's Environmental Health, agreed with Dr. Samet, calling the new study "excellent," but warning that some people appear to be far more sensitive to P.A.H.'s than others, and that fetuses, particularly, can be harmed from exposure to this kind of pollution.
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Hillary, The World's Smartest Woman™ probably feels pretty stupid right about now.
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