Academic journal article Environmental Health Perspectives

Chemical Analysis of World Trade Center Fine Particulate Matter for Use in Toxicologic Assessment. (World Trade Center: Mini-Monograph)

Academic journal article Environmental Health Perspectives

Chemical Analysis of World Trade Center Fine Particulate Matter for Use in Toxicologic Assessment. (World Trade Center: Mini-Monograph)

Article excerpt

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 [micro]m (P[M.sub.2.5])], 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 P[M.sub.2.5] fraction was isolated on filters. Here we report the chemical and physical properties of P[M.sub.2.5] derived from these samples and compare them with P[M.sub.2.5] 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 [micro]m) 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 P[M.sub.2.5] fraction. Analysis of WTC P[M.sub.2.5] 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 P[M.sub.2.5] 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 P[M.sub.2.5] could potentially cause toxic respiratory effects. Key words: carbon analysis, ICP-AES, ICP-MS, inhalation toxicology, neutron activation analysis, scanning electron microscopy, X-ray diffraction, X-ray fluorescence. Environ Health Perspect 111:972-980 (2003). doi: 10.1289/ehp.5930 available via http://dx.doi.org/[Online 20 November 2002]

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The attack on the World Trade Center (WTC) in New York City on 11 September 2001, in addition to causing the immediate and tragic loss of thousands of lives, resulted in the release of significant quantities of pollutants into the environment of the surrounding neighborhoods, including particulate matter (PM), asbestos, metals, and organic compounds [U.S. Environmental Protection Agency (U.S. EPA) 2002b]. Dust infiltrated indoors into homes and apartments, in many cases up to several inches in depth. Fires at the WTC site continued for several months before finally being extinguished, and recovery and reconstruction efforts contributed to emissions of fine [particulate matter with a mass median aerodynamic diameter (MMAD) < 2.5 [micro]m; P[M.sub.2.5]], coarse (> 2.5 and < 10 [micro]m; P[M.sub.2.5-10]), and larger (> 10 [micro]m) PM fractions. As people have returned to their residences and businesses, potential exposure issues are associated with redispersal of residual dust.

Recent studies have assessed the chemical and physical properties of bulk samples of WTC PM. The dust particles from the WTC site appear to be quite alkaline in nature, probably because of partial dissolution of concrete, gypsum, and glass fiber particles [U.S. Geological Survey (USGS) 2002]. Lioy and co-workers (2002) found that bulk settled--dust samples of WTC PM were composed of particles of cement, carbon, cellulose, and several fiber types including mineral wool, fiberglass, cellulose, and asbestos. These authors also found significant concentrations of phthalate esters, polycyclic aromatic hydrocarbons (PAHs), and other hydrocarbons (Offenberg et al. …

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