"Many of the workers we assessed reported coughing, wheezing, and sore throats while working at Ground Zero. These symptoms seemed to increase the longer they worked at the site. The good news is that we did not find unhealthy levels of asbestos, but we don't know what the long-term health risks may be regarding exposure to other airborne contaminants at the site," explains Alison S. Geyh, PhD, chief investigator and assistant professor of environmental health sciences at the Johns Hopkins Bloomberg School of Public Health.
The exposure and health assessment was conducted between October 2001 and April 2002. The investigators examined the workers' airborne exposures to asbestos, particulate matter, and volatile organic compounds. In October, airborne contaminants were measured at numerous locations at Ground Zero and on truck drivers who hauled wreckage away from the site. The respiratory health of the truck drivers and other debris-removal workers was assessed two months later. At that time, a respiratory health questionnaire was administered to the workers. In addition, lung function was measured using spirometry. Additional airborne contaminants measurements were collected in April and compared to what was measured in October.
The air monitoring effort detected small amounts of asbestos. Investigators say exposures were generally low and did not exceed health exposure guidelines. "Low level exposures to asbestos, occurring for a short period of time relative to a working lifetime, suggest that these truck drivers are unlikely to be at a significant increased risk of asbestos-related disease," said Patrick Breysse, PhD, an investigator on the project and professor of environmental health sciences at the Johns Hopkins Bloomberg School of Public Health.
Airborne particulate matter measured at the site was highly variable in both composition and size depending on conditions at Ground Zero such as how aggressively the fires were burning, how actively the debris was being removed, or how well dust suppression was being conducted.
Responses to the questionnaire indicate that respiratory symptoms, such as sore throat, coughing, and wheezing were widespread among workers at the site. On average the more days worked, the more frequent and severe the symptoms were. Lung function results based on spirometric measurement did not indicate that there was any extensive impairment among the workers surveyed.
Julie Herbstman, ScM, a member of the investigation team, said, "Now we are in the process of tracking this group of workers into the future to document any potential changes in health status."
In May, the National Institute of Environmental Health Sciences awarded the Johns Hopkins Bloomberg School of Public Health a grant to continue assessing the health of workers involved in the cleanup of the World Trade Center site. Over the next year, Dr. Geyh and her colleagues will develop a registry of the estimated 6,000 to 7,000 workers involved in removing and transporting debris from the World Trade Center site. The registry will be used for future studies to assess the health of these workers.
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