Faculty Bibliography

The catastrophic destruction of the World Trade Center (WTC) on 11 September 2001 caused the release of high levels of airborne pollutants into the local environment. To assess the toxicity of fine particulate matter [particulate matter with a mass median aerodynamic diameter < 2.5 microm (PM2.5)], which may adversely affect the health of workers and residents in the area, we collected fallen dust samples on 12 and 13 September 2001 from sites within a half-mile of Ground Zero. Samples of WTC dust were sieved, aerosolized, and size-separated, and the PM2.5 fraction was isolated on filters. Here we report the chemical and physical properties of PM2.5 derived from these samples and compare them with PM2.5 fractions of three reference materials that range in toxicity from relatively inert to acutely toxic (Mt. St. Helens PM; Washington, DC, ambient air PM; and residual oil fly ash). X-ray diffraction of very coarse sieved WTC PM (< 53 microm) identified calcium sulfate (gypsum) and calcium carbonate (calcite) as major components. Scanning electron microscopy confirmed that calcium-sulfur and calcium-carbon particles were also present in the WTC PM2.5 fraction. Analysis of WTC PM2.5 using X-ray fluorescence, neutron activation analysis, and inductively coupled plasma spectrometry showed high levels of calcium (range, 22-33%) and sulfur (37-43% as sulfate) and much lower levels of transition metals and other elements. Aqueous extracts of WTC PM2.5 were basic (pH range, 8.9-10.0) and had no evidence of significant bacterial contamination. Levels of carbon were relatively low, suggesting that combustion-derived particles did not form a significant fraction of these samples recovered in the immediate aftermath of the destruction of the towers. Because gypsum and calcite are known to cause irritation of the mucus membranes of the eyes and respiratory tract, inhalation of high doses of WTC PM2.5 could potentially cause toxic respiratory effects

Pollutants originating from the destruction of the World Trade Center (WTC) in New York City on 11 September 2001 have been reported to cause adverse respiratory responses in rescue workers and nearby residents. We examined whether WTC-derived fine particulate matter [particulate matter with a mass median aerodynamic diameter < 2.5 microm (PM2.5)] has detrimental respiratory effects in mice to contribute to the risk assessment of WTC-derived pollutants. Samples of WTC PM2.5 were derived from settled dust collected at several locations around Ground Zero on 12 and 13 September 2001. Aspirated samples of WTC PM2.5 induced mild to moderate degrees of pulmonary inflammation 1 day after exposure but only at a relatively high dose (100 microg). This response was not as great as that caused by 100 microg PM2.5 derived from residual oil fly ash (ROFA) or Washington, DC, ambient air PM [National Institute of Standards and Technology, Standard Reference Material (SRM) 1649a]. However, this same dose of WTC PM2.5 caused airway hyperresponsiveness to methacholine aerosol comparable to that from SRM 1649a and to a greater degree than that from ROFA. Mice exposed to lower doses by aspiration or inhalation exposure did not develop significant inflammation or hyperresponsiveness. These results show that exposure to high levels of WTC PM2.5 can promote mechanisms of airflow obstruction in mice. Airborne concentrations of WTC PM2.5 that would cause comparable doses in people are high (approximately 425 microg/m3 for 8 hr) but conceivable in the aftermath of the collapse of the towers when rescue and salvage efforts were in effect. We conclude that a high-level exposure to WTC PM2.5 could cause pulmonary inflammation and airway hyperresponsiveness in people. The effects of chronic exposures to lower levels of WTC PM2.5, the persistence of any respiratory effects, and the effects of coarser WTC PM are unknown and were not examined in these studies. Degree of exposure and respiratory protection, individual differences in sensitivity to WTC PM2.5, and species differences in responses must be considered in assessing the risks of exposure to WTC PM2.5

The explosion and collapse of the World Trade Center (WTC) was a catastrophic event that produced an aerosol impacting many workers, residents, and commuters during the first few days after September 11, 2001. During the initial days that followed, 14 bulk samples of the settled dust were collected at locations surrounding the epicenter of the disaster, including one indoor location. Some samples were analyzed for many potential hazards, including inorganic and organic constituents as well as morphology. The results of the analyses for persistent organic pollutants are described herein, including polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and select organochlorine pesticides on settled dust samples. The sigma86-PCBs comprising less than 0.001% by mass of the bulk in the three bulk samples analyzed indicated that PCBs were of limited significance in the total settled dust across lower Manhattan. Likewise, organochlorine pesticides, including chlordanes, hexachlorobenzene, heptachlor, 4,4'-DDE, 2,4'-DDT, 4,4'-DDT, and Mirex, were found at low concentrations in the bulk samples. Conversely, the sigma37-PAHs comprised up to nearly 0.04% (<0.005-0.039%) by mass of the bulk settled dust in the six bulk samples. Further size segregation of these three initial bulk samples and seven additional samples indicates that sigma37-PAHs were found in higher concentrations on relatively large particles (10-53 microm), representing up to 0.04% of the total dust mass. Significant concentrations were also found on fine particles (<2.5 microm), often accounting for approximately 0.005% by mass. We estimate that approximately 100-1000 tons of sigma37-PAHs were spread over a localized area immediately after the WTC disaster on September 11

Respiratory-tract infection, specifically pneumonia, contributes substantially to the increased morbidity and mortality among elderly individuals exposed to airborne particulate matter of <10 micro m diameter (PM(10)). These epidemiological findings suggest that PM(10) may act as an immunosuppressive factor that can undermine normal pulmonary antimicrobial defense mechanisms. To investigate whether, and how, compromised pulmonary immunocompetence might contribute to increased mortality, two sets of laboratory studies were performed. The first examined the effects of a single inhalation exposure to concentrated ambient PM(2.5) (CAPS) from New York City air on pulmonary/systemic immunity and on the susceptibility of exposed aged rats to subsequent infection with Streptococcus pneumoniae. The second set of studies determined whether CAPS exposure, at a concentration approximating or somewhat greater than the promulgated 24-h NAAQS of 65 micro g/m(3), could exacerbate an ongoing infection. Taken together, results demonstrated that a single exposure of healthy animals to CAPS had little effect on pulmonary immune function or bacterial clearance during subsequent challenge with S. pneumoniae. Alterna-tively, CAPS exposure of previously infected rats significantly increased bacterial burdens and decreased percentages of lavageable neutrophils and proinflammatory cytokine levels compared to those in infected filtered-air-exposed controls. These studies demonstrate that a single exposure to ambient PM(2.5) compromises a host's ability to handle ongoing pneumococcal infections and support the epidemiological findings of increased pneumonia-related deaths in ambient PM-exposed elderly individuals