VOC sampling locations table for Ground Zero area, Jan 2002

NYC 9/11 Public Portal Document

Executive Summary

The goal of the experiments described in this report was to evaluate the toxicity of fine particulate matter (PM) derived from the destruction of the World Trade Center (WTC) on the respiratory tract ofmice, and thereby contribute to the short-term health risk assessment of WTC PM being conducted by the Environmental Protection Agency. The adopted approach allowed a comparison of the intrinsic acute toxicity of fine WTC PM in the respiratory tract to well-studied PM reference samples that range in toxicity from essentially inert to quite toxic. The fundamental question was whether fine WTC PM was uniquely highly toxic.

This toxicological research complements efforts by EPA and other organizations to assess the extent and level of worker and public exposures to PM derived from the WTC disaster and recovery efforts. This research is informative, but it is of limited scope, with a focus on the toxicological effects of the fine fraction of WTC dust from a single exposure. A more complete characterization of potential health effects would include consideration of other size fractions, repeated exposures, additional doses and endpoints, and responses in species or strains of differing sensitivity. It was not possible to assess these other considerations in the present study.

Fallen dust samples were collected on September 12 and 13 from various sites around Ground Zero, and the fine PM fraction (< 2.5 microns in diameter; PM2 5) was isolated on filters. PM2 5 was extracted from the filters and extensively analyzed by several chemical and physical techniques. A dose-response study in mice was conducted comparing aspirated WTC PM25 (pooled from 7 different locations near the WTC site) with low and high toxicity PM2 5 control samples (Mt. St. Helens and residual oil fly ash (ROFA), respectively). An acute nose-only inhalation exposure study was conducted on one WTC PM2 5 sample, since upper airway irritation has been a primary complaint of those living and working in the WTC area. Finally, a short-term time course study was conducted comparing aspirated samples from the 7 different locations with each other and with a standard PM2 5 sample (NIST 1649a, an ambient air PM sample collected in Washington, DC).

Fine size-fi-actionated WTC PM2 5 was composed primarily of calcium-based compounds such as calcium sulfate (gypsum) and calcium carbonate (calcite, the main component of limestone). These and other compounds and elements found in the WTC PM25 samples are indicative of crushed building materials such as cement, concrete aggregate, ceiling tiles, and wallboard. 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. Gypsum and calcite are known to cause irritation of the mucus membranes of the eyes and respiratory tract.

Samples of WTC PM2.5 induced mild to moderate degrees of inflammation when administered at a relatively high dose (100 pg) directly into the airways of mice. The pulmonary inflammatory response was not as great as that caused by the reference PMj j samples (toxic ROFA and ambient air NIST 1649a). However, this same dose of WTC PM2.5 caused airway hyperresponsiveness (a

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