A novel system to generate WTC dust particles for inhalation exposures

Abstract

First Responders (FR) present at Ground Zero within the first 72-hr after the WTC (World Trade Center) collapse have progressively exhibited significant respiratory injury. The majority (>96%) of WTC dusts were >10 μm and no studies have examined potential health effects of this size fraction. This study sought to develop a system to generate and deliver supercoarse (10–53 μm) WTC particles to a rat model in a manner that mimicked FR exposure scenarios. A modified Fishing Line generator was integrated onto an intratracheal inhalation (ITIH) system that allowed for a bypassing of the nasal passages so as to mimic FR exposures. Dust concentrations were measured gravimetrically; particle size distribution was measured via elutriation. Results indicate that the system could produce dusts with 23 μm MMAD at levels up to ≥ 1200 mg/m3. To validate system utility, F344 rats were exposed for 2-hr to ≈100 mg WTC dust/m3. Exposed rats had significantly increased lung weight and levels of select tracer metals 1-hr post-exposure. Using this system, it is now possible to conduct relevant inhalation exposures to determine adverse WTC dusts impacts on the respiratory system. Furthermore, this novel integrated Fishing Line-ITIH system could potentially be used in the analyses of a wide spectrum of other dusts/pollutants of sizes previously untested or delivered to the lungs in ways that did not reflect realistic exposure scenarios.

Acute high-level exposure to WTC particles alters expression of genes associated with oxidative stress and immune function in the lung

“…The increase in weight was more than predicted as a result of the dust being deposited during exposure (≈3 mg; Vaughan et al, 2014). We have attributed this to, in part, rapid induction of edema/changes in post-exposure physiology.…”

“…Dust atmospheres were generated via a custom-built Fishing Line system to generate nanoparticle/precious material atmospheres for inhalation studies (Ledbetter et al, 1998; Vaughan et al, 2014). All dilution air required for dust generation was composed of a mixture of filtered air and Isoflurane (ISO; IsoFlo, Abbott Laboratories, North Chicago, IL) in O 2 carrier gas (2.5% final concentration after mixing with house air).…”

“…An atmosphere of ≈100 mg WTC dust/m 3 was used; this dose was chosen as a conservative estimate to model the rat exposure to correspond to one likely to have occurred in mouth-breathing FR exposed to Ground Zero levels of ≈750–1000 mg WTC dust/m 3 (Asgharian, Personal Communication). All rats were exposed to the WTC 53 - dusts or ISO alone in an intratracheal inhalation (ITIH) integrated system (Vaughan et al, 2014) that allowed the WTC particles, including those with d a > 2.5 µm, to circumvent the rat nasal region so that they were introduced (and deposited) in the lungs in a manner to mimic mouth-breathing FR.…”

“…While 1.5% of the dusts (by mass) collected at/around Ground Zero during 9/11-9/13 were fine (aerodynamic diameter ≤2.5 µm), and ≈0.5% were coarse, the majority (>96%) were supercoarse (≥10µm) (see Vaughan et al, 2014). Several WTC dust constituents were believed to pose adverse health effects, including metals, polychlorinated biphenyls, dioxins, asbestos, volatile organics, polycyclic aromatic hydrocarbons, and synthetic vitreous fibers (SVF) (Supplemental References).…”

“…unfractionated part after initial sieving to remove supersize [>53 µm] debris) WTC dusts to a rat model at representative levels and in a manner to mimic FR mouth breathing (Vaughan et al, 2014). Via this system, rats were exposed to a single dose of WTC dust (from 9/11–13/01 period) that approximated a level that FR would have faced in the 24–72 h period after the buildings collapsed.…”