Assessment of Inhalation Exposures and Potential Health Risks to the General Population that Resulted from the Collapse of the World Trade Center Towers

National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, 1200 Pennsylvania Ave., Washington, DC 22314, USA.
Risk Analysis (Impact Factor: 2.5). 11/2007; 27(5):1203-21. DOI: 10.1111/j.1539-6924.2007.00956.x
Source: PubMed


In the days following the collapse of the World Trade Center (WTC) towers on September 11, 2001 (9/11), the U.S. Environmental Protection Agency (EPA) initiated numerous air monitoring activities to better understand the ongoing impact of emissions from that disaster. Using these data, EPA conducted an inhalation exposure and human health risk assessment to the general population. This assessment does not address exposures and potential impacts that could have occurred to rescue workers, firefighters, and other site workers, nor does it address exposures that could have occurred in the indoor environment. Contaminants evaluated include particulate matter (PM), metals, polychlorinated biphenyls, dioxins, asbestos, volatile organic compounds, particle-bound polycyclic aromatic hydrocarbons, silica, and synthetic vitreous fibers (SVFs). This evaluation yielded three principal findings. (1) Persons exposed to extremely high levels of ambient PM and its components, SVFs, and other contaminants during the collapse of the WTC towers, and for several hours afterward, were likely to be at risk for acute and potentially chronic respiratory effects. (2) Available data suggest that contaminant concentrations within and near ground zero (GZ) remained significantly elevated above background levels for a few days after 9/11. Because only limited data on these critical few days were available, exposures and potential health impacts could not be evaluated with certainty for this time period. (3) Except for inhalation exposures that may have occurred on 9/11 and a few days afterward, the ambient air concentration data suggest that persons in the general population were unlikely to suffer short-term or long-term adverse health effects caused by inhalation exposures. While this analysis by EPA evaluated the potential for health impacts based on measured air concentrations, epidemiological studies conducted by organizations other than EPA have attempted to identify actual impacts. Such studies have identified respiratory effects in worker and general populations, and developmental effects in newborns whose mothers were near GZ on 9/11 or shortly thereafter. While researchers are not able to identify specific times and even exactly which contaminants are the cause of these effects, they have nonetheless concluded that exposure to WTC contaminants (and/or maternal stress, in the case of developmental effects) resulted in these effects, and have identified the time period including 9/11 itself and the days and few weeks afterward as a period of most concern based on high concentrations of key pollutants in the air and dust.

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    • "That is, the analytes were chosen a priori to optimize sensitivity and specificity. As such, we restricted ourselves to certain compounds that are presumed indicative of the totality of exposure to products of incomplete combustion; this approach has been used for environmentally derived samples for assessments of other fire related exposures including from the 9/11 New York City World Trade Center (WTC) disaster (Lorber et al 2007, Pleil et al 2004, Pleil et al 2006). We note that there are previous breath based studies of firefighters for assessing carbon monoxide (CO) exposures (Cone et al 2005, Dunn et al 2009, Miranda et al 2012), but that this is the first study wherein organics exposures were directly assessed using breath biomarkers. "
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    • "Mathematical models suggest that because 95% of human exposure to dioxin and furans tends to occur through food consumption and only 1% by inhalation, WTC pile workers exposed to high levels of dioxin for 3 months had only an estimated 17% higher burden of these two toxins after 3 months of exposure, and modeled body burden would have returned to near background levels after leaving the area or after ambient levels dropped to background concentrations (by December 2001 in the areas near the WTC site and by May 2002 at the site) [12]. Findings from these models suggest that exposures to dioxins and furans did not significantly increase lifetime cancer risk [12] [14]. "
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