Induced Sputum in Firefighters Exposed to WTC Dust
New York City Firefighters (FDNY-FFs) were exposed to particulate matter and combustion/pyrolysis products during and after the World Trade Center (WTC) collapse. Ten months after the collapse, induced sputum (IS) samples were obtained from 39 highly exposed FDNY-FFs (caught in the dust cloud during the collapse on 11 September 2001) and compared to controls to determine whether a unique pattern of inflammation and particulate matter deposition, compatible with WTC dust, was present. Control subjects were 12 Tel-Aviv, Israel, firefighters (TA-FFs) and 8 Israeli healthcare workers who were not exposed to WTC dust. All controls volunteered for this study, had never smoked, and did not have respiratory illness. IS was processed by conventional methods. Retrieved cells were differentially counted, and metalloproteinase-9 (MMP-9), particle size distribution (PSD), and mineral composition were measured. Differential cell counts of FDNY-FF IS differed from those of health care worker controls (p < 0.05) but not from those of TA-FFs. Percentages of neutrophils and eosinophils increased with greater intensity of WTC exposure (< 10 workdays or ≥ 10 workdays; neutrophils p = 0.046; eosinophils p = 0.038). MMP-9 levels positively correlated to neutrophil counts (p = 0.002; r = 0.449). Particles were larger and more irregularly shaped in FDNY-FFs (1-50 µm; zinc, mercury, gold, tin, silver) than in TA-FFs (1-10 µm; silica, clays). PSD was similar to that of WTC dust samples. In conclusion, IS from highly exposed FDNY-FFs demonstrated inflammation, PSD, and particle composition that was different from nonexposed controls and consistent with WTC dust exposure.
In the aftermath of September 11th, the clouds of dust and smoke that stood for days in place of the World Trade Center's (WTC) twin towers raised serious health concerns among exposed workers and residents. The Fire Department of New York City (FDNY) operated a continuous rescue/recovery effort from 11 September 2001 through May 2002. Nearly every FDNY firefighter (FDNY-FF) worked at the site during the first weeks, reporting numerous exposures to airborne particulates and products of combustion/pyrolysis [Centers for Disease Control and Prevention (CDC) 2002a] that have since been implicated in the development of "WTC cough," airways obstruction, and inflammatory bronchial hyperreactivity (Banauch et al. 2003; Feldman et al. 2004; Prezant et al. 2002). Appropriate respiratory protection was not readily available in the first week (CDC 2002b). Firefighters were not the only ones affected. Respiratory symptoms and pulmonary dysfunction has been reported in other WTC rescue workers (Safirstein et al. 2003; Saltzman et al. 2004; Skloot et al. 2004) and in Manhattan residents living near the site. (CDC 2002c; Szema et al. 2004).
Environmental site studies after the collapse reported concentrations of airborne and respirable particulates ranging up to 100 mg/m and 1 mg/m, respectively (CDC 2002a). Analysis of settled WTC dust samples collected 5 and 6 days postcollapse from areas east of the WTC revealed a complex mixture of particulate matter and combustion/pyrolysis products, composed mostly of building debris fibers (e.g., mineral wool, fiberglass, asbestos, wood, paper, cotton) contaminated with polycyclic hydrocarbons (Landrigan et al. 2004; Lioy et al. 2002). More than 90% of the particles in these bulk samples were > 10 µm in diameter and many were fibers with widths < 5 µm and lengths > 10 µm. Further, many were caustic cement particles with a pH of 9-11 (Landrigan et al. 2004; Lioy et al. 2002).
Bronchoalveolar lavage (BAL) recovered significant quantities of fly ash, degraded fibrous glass, and asbestos fibers along with evidence for a significant inflammatory response (70% eosinophils and increased levels of interleukin-5) in one FDNY-FF hospitalized with acute eosinophilic pneumonitis several weeks after WTC exposure (Rom et al. 2002). Although BAL is an important diagnostic tool (Davison et al. 1983; Dodson et al. 1991; Rom et al. 2002), it is an invasive procedure unsuitable for screening or repeated follow-up evaluations after exposure to dusts or combustion/pyrolysis products. In fact, no FDNY-FF has agreed to enroll in a BAL screening program.
Induced sputum (IS) provides a noninvasive alternative method to study respired particulate matter and the lung's inflammatory response (Fireman et al. 1999a; Maestrelli et al. 1994; Marek et al. 2001; Quirce et al. 2001). Qualitative and quantitative analysis of chemical particles among silica and hard metal workers showed similar patterns when recovered by IS and BAL (Fireman et al. 1999a). IS analyzed by scanning electron microscope (SEM) has demonstrated dust exposures in patients with occupational lung diseases (Cohen et al. 1999; Fireman et al. 2004a; Lerman et al. 2003b; Paris et al. 2002), and IS analyzed by particle size distribution (PSD) has shown significant differences between workers with and without exposure to hazardous dust (Lerman et al. 2003b).
This study is the first to use IS methodology to assess respired particulate matter and the inflammatory response of the lung after exposure to WTC dust. Our objective was to determine if IS collected from highly exposed FDNY-FFs 10 months after the collapse demonstrates a unique pattern of inflammation and particulate matter deposition compatible with WTC dust. Inflammation was assessed by differential cell counts and by measuring metalloproteinase-9 (MMP-9), a cytokine involved in airways inflammation (Montano et al. 2004) and remodeling (Atkinson and Senior 2003). Particulate matter was assessed by size distribution, mineral composition, and by comparison to settled dust samples collected at the WTC site.
New York City Firefighters (FDNY-FFs) were exposed to particulate matter and combustion/pyrolysis products during and after the World Trade Center (WTC) collapse. Ten months after the collapse, induced sputum (IS) samples were obtained from 39 highly exposed FDNY-FFs (caught in the dust cloud during the collapse on 11 September 2001) and compared to controls to determine whether a unique pattern of inflammation and particulate matter deposition, compatible with WTC dust, was present. Control subjects were 12 Tel-Aviv, Israel, firefighters (TA-FFs) and 8 Israeli healthcare workers who were not exposed to WTC dust. All controls volunteered for this study, had never smoked, and did not have respiratory illness. IS was processed by conventional methods. Retrieved cells were differentially counted, and metalloproteinase-9 (MMP-9), particle size distribution (PSD), and mineral composition were measured. Differential cell counts of FDNY-FF IS differed from those of health care worker controls (p < 0.05) but not from those of TA-FFs. Percentages of neutrophils and eosinophils increased with greater intensity of WTC exposure (< 10 workdays or ≥ 10 workdays; neutrophils p = 0.046; eosinophils p = 0.038). MMP-9 levels positively correlated to neutrophil counts (p = 0.002; r = 0.449). Particles were larger and more irregularly shaped in FDNY-FFs (1-50 µm; zinc, mercury, gold, tin, silver) than in TA-FFs (1-10 µm; silica, clays). PSD was similar to that of WTC dust samples. In conclusion, IS from highly exposed FDNY-FFs demonstrated inflammation, PSD, and particle composition that was different from nonexposed controls and consistent with WTC dust exposure.
In the aftermath of September 11th, the clouds of dust and smoke that stood for days in place of the World Trade Center's (WTC) twin towers raised serious health concerns among exposed workers and residents. The Fire Department of New York City (FDNY) operated a continuous rescue/recovery effort from 11 September 2001 through May 2002. Nearly every FDNY firefighter (FDNY-FF) worked at the site during the first weeks, reporting numerous exposures to airborne particulates and products of combustion/pyrolysis [Centers for Disease Control and Prevention (CDC) 2002a] that have since been implicated in the development of "WTC cough," airways obstruction, and inflammatory bronchial hyperreactivity (Banauch et al. 2003; Feldman et al. 2004; Prezant et al. 2002). Appropriate respiratory protection was not readily available in the first week (CDC 2002b). Firefighters were not the only ones affected. Respiratory symptoms and pulmonary dysfunction has been reported in other WTC rescue workers (Safirstein et al. 2003; Saltzman et al. 2004; Skloot et al. 2004) and in Manhattan residents living near the site. (CDC 2002c; Szema et al. 2004).
Environmental site studies after the collapse reported concentrations of airborne and respirable particulates ranging up to 100 mg/m and 1 mg/m, respectively (CDC 2002a). Analysis of settled WTC dust samples collected 5 and 6 days postcollapse from areas east of the WTC revealed a complex mixture of particulate matter and combustion/pyrolysis products, composed mostly of building debris fibers (e.g., mineral wool, fiberglass, asbestos, wood, paper, cotton) contaminated with polycyclic hydrocarbons (Landrigan et al. 2004; Lioy et al. 2002). More than 90% of the particles in these bulk samples were > 10 µm in diameter and many were fibers with widths < 5 µm and lengths > 10 µm. Further, many were caustic cement particles with a pH of 9-11 (Landrigan et al. 2004; Lioy et al. 2002).
Bronchoalveolar lavage (BAL) recovered significant quantities of fly ash, degraded fibrous glass, and asbestos fibers along with evidence for a significant inflammatory response (70% eosinophils and increased levels of interleukin-5) in one FDNY-FF hospitalized with acute eosinophilic pneumonitis several weeks after WTC exposure (Rom et al. 2002). Although BAL is an important diagnostic tool (Davison et al. 1983; Dodson et al. 1991; Rom et al. 2002), it is an invasive procedure unsuitable for screening or repeated follow-up evaluations after exposure to dusts or combustion/pyrolysis products. In fact, no FDNY-FF has agreed to enroll in a BAL screening program.
Induced sputum (IS) provides a noninvasive alternative method to study respired particulate matter and the lung's inflammatory response (Fireman et al. 1999a; Maestrelli et al. 1994; Marek et al. 2001; Quirce et al. 2001). Qualitative and quantitative analysis of chemical particles among silica and hard metal workers showed similar patterns when recovered by IS and BAL (Fireman et al. 1999a). IS analyzed by scanning electron microscope (SEM) has demonstrated dust exposures in patients with occupational lung diseases (Cohen et al. 1999; Fireman et al. 2004a; Lerman et al. 2003b; Paris et al. 2002), and IS analyzed by particle size distribution (PSD) has shown significant differences between workers with and without exposure to hazardous dust (Lerman et al. 2003b).
This study is the first to use IS methodology to assess respired particulate matter and the inflammatory response of the lung after exposure to WTC dust. Our objective was to determine if IS collected from highly exposed FDNY-FFs 10 months after the collapse demonstrates a unique pattern of inflammation and particulate matter deposition compatible with WTC dust. Inflammation was assessed by differential cell counts and by measuring metalloproteinase-9 (MMP-9), a cytokine involved in airways inflammation (Montano et al. 2004) and remodeling (Atkinson and Senior 2003). Particulate matter was assessed by size distribution, mineral composition, and by comparison to settled dust samples collected at the WTC site.
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