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Cancer Risk Fears From 9/11 Attack Eased with sidebar: Registry Seeks to Track 9/11 Health Effects
Mike Mitka
Journal of the American Medical Association
2004;292:914-915.
http://jama.amaassn.org/cgi/content/full/292/8/914?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=Cancer+Risk+Fears+From+9%2F11+Attack+Eased%22&searchid=1093438465041_1131&stored_search=&FIRSTINDEX=0&journalcode=jama
Exposure to large quantities of known carcinogens released during the September 11, 2001, collapse of the World Trade Center in New York City and its subsequent cleanup apparently should have little effect on individuals who lived or worked in the area, said researchers from the University of North Carolina, Chapel Hill.
The researchers estimated that exposure to certain carcinogens released at Ground Zero only added a one person per 100 million increase in lifetime risk for individuals who lived or worked in the area. Their conclusions appeared in an online edition of the Proceedings of the National Academy of Sciences of the United States of America on July 27 (http://www.pnas.org/cgi/doi/10.1073/pnas.0404499101).
The carcinogens studied were polycyclic aromatic hydrocarbons (PAHs), compounds formed by the incomplete combustion of organic materials such as fuel, wood, and even cooked meat. They often attach to particulate matter such as soot and circulate in the atmosphere, where they can be inhaled.
Following the collapse of the World Trade Center's twin towers, fires burned through December 20, 2001. The fires, initiated by the ignition of approximately 91 000 L of jet fuel from the airliners that crashed into the buildings, spread to an estimated 100 000 tons of organic debris, 490 000 L of transformer oil, 380 000 L of heating and diesel fuel, and gasoline from several thousand automobiles stored beneath the towers, the researchers said. The fires, plus emissions from construction machinery operated at the site after the collapse, created between 100 and 1000 tons of PAHs that circulated and settled primarily in lower Manhattan.
Stephen M. Rappaport, PhD, coauthor of the study and professor of environmental health at North Carolina, said the team focused on PAHs because these compounds are always associated with burning organic materials and cancer risk. That connection was first shown in 1775 when exposure to PAH-containing soot among British chimney sweeps was linked with the appearance of squamous cell carcinomas. Since then, PAHs have also been associated with human cancers of the skin, lungs, and bladder.
"Whenever you burn hydrocarbon fuels you produce PAHs," Rappaport said. "But there was no research on risk of exposure to PAHs following the collapse of the World Trade Center."
The researchers analyzed 243 air samples that had been collected from 4 areas surrounding the collapse site for 200 days following September 11. Three of the sites were at the fence line of Ground Zero; the fourth was on the 16th floor of an office building about 0.5 km from Ground Zero. The investigators found air concentrations of PAHs on September 14 ranged from 1.3 to 15 ng/m3. By day 200, PAH levels had returned to background levels, comparable with the range of 0.03 to 0.50 ng/m3 typically seen in Los Angeles.
The researchers estimated that over a 70-year lifetime, 15.6 people per 100 million will develop cancer due to baseline PAH levels. The new data suggest 16.7 people per 100 million will develop cancer due to elevated PAH exposure related to the World Trade Center disaster, the researchers said.
While the findings offer some reassurance, Rappaport cautioned that they pertain only to individuals with jobs or residences in lower Manhattan, not to emergency personnel and construction and demolition crews working at Ground Zero, who could have had more intense interaction with PAHs.
The study also does not rule out potential adverse reproductive effects among the children of women were pregnant or conceived during that period. In fact, research involving 187 women present in lower Manhattan during the 3 weeks after the towers collapse found an apparent association between maternal exposure to the disaster and intrauterine growth restriction (when compared to a cohort of pregnant women who had not been in lower Manhattan), an effect that may have been mediated through exposure to PAH or particulate matter (JAMA. 2003;290:595-596).
Rappaport also noted that the study focused only on outdoor air, which is transient in nature. Sizable amounts of PAH-containing soot remains trapped by the buildings in the area, he said.
"People living in lower Manhattan had a great deal of contamination in their apartments; the dirt and soot blew in and can still be there," Rappaport noted. "Also, these materials could be recycled throughout the buildings by the heating and air-conditioning systems."
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Sidebar to the article above
Registry Seeks to Track 9/11 Health Effects
Researchers are hoping that a registry of more than 50 000 individuals living or working near the World Trade Center on and after September 11, 2001, will help them track health effects caused by exposure to substances from the destruction of the twin towers.
The World Trade Center Health Registry is recruiting individuals who worked or lived in lower Manhattan on September 11, 2001, and workers involved in the rescue, recovery, and cleanup any time between the attack and June 30, 2002. They are to be followed for 20 years and compared with the general population.
Besides providing two decades worth of data for future research, the registry should help alert patients and their physicians about potential diseases and conditions associated with the catastrophe, said Pauline Thomas, MD, of the New York City Department of Health and Mental Hygiene, which is overseeing the registry in collaboration with the US Agency for Toxic Substances and Disease Registry.
Registry participants complete a 30-minute telephone survey regarding exposures and health problems. Registry researchers will focus on respiratory and mental health, as well as cancer rates.
But there are factors that are likely to limit the effectiveness of the registry as a research tool, including large variations in exposure levels among participants and the self-selecting, nonrandomized nature of participants who may not be representative of all those exposed, noted Robert Morris, MD, PhD, of Tufts University in Boston. Although the registry should be able to uncover trends in diseases where diagnosis is clear cut, such as cancer, it will probably be less useful in determining real levels of concern for conditions such as multiple-chemical sensitivity.
"You can see where in a few years we'll be talking about `Trade Tower syndrome'-a group of symptoms associated with having been there," Morris said. "With such a varied cohort and a wide range of exposure levels, it may be hard to link any specific outcome to a specific exposure."-M.M.
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