Academic journal article Environmental Health Perspectives

Inhaled Concentrated Ambient Particles Are Associated with Hematologic and Bronchoalveolar Lavage Changes in Canines

Academic journal article Environmental Health Perspectives

Inhaled Concentrated Ambient Particles Are Associated with Hematologic and Bronchoalveolar Lavage Changes in Canines

Article excerpt

Pulmonary inflammatory and hematologic responses of canines were studied after exposure to concentrated ambient particles (CAPs) using the Harvard ambient particle concentrator (HAPC). For pulmonary inflammatory studies, normal dogs were exposed in pairs to either CAPs or filtered air (paired studies) for 6 hr/day on 3 consecutive days. For hematologic studies, dogs were exposed for 6 hr/day for 3 consecutive days with one receiving CAPs while the other was simultaneously exposed to filtered air; crossover of exposure took place the following week (crossover studies). Physicochemical characterization of CAPs exposure samples included measurements of particle mass, size distribution, and composition. No statistical differences in biologic responses were found when all CAPs and all sham exposures were compared. However, the variability in biologic response was considerably higher with CAPs exposure. Subsequent exploratory graphical analyses and mixed linear regression analyses suggested associations between CAPs constituents and biologic responses. Factor analysis was applied to the compositional data from paired and crossover experiments to determine elements consistently associated with each other in CAPs samples. In paired experiments, four factors were identified; in crossover studies, a total of six factors were observed. Bronchoalveolar lavage (BAL) and hematologic data were regressed on the factor scores. Increased BAL neutrophil percentage, total peripheral white blood cell (WBC) counts, circulating neutrophils, and circulating lymphocytes were associated with increases in the aluminum/silicon factor. Increased circulating neutrophils and increased BAL macrophages were associated with the vanadium/nickel factor. Increased BAL neutrophils were associated with the bromine/lead factor when only the compositional data from the third day of CAPs exposure were used. Significant decreases in red blood cell counts and hemoglobin levels were correlated with the sulfur factor. BAL or hematologic parameters were not associated with increases in total CAPs mass concentration: These data suggest that CAPs inhalation is associated with subtle alterations in pulmonary and systemic cell profiles, and specific components of CAPs may be responsible for these biologic responses. Key words: bronchoalveolar lavage, canines, environmental particles, hematology, inflammation. Environ Health Perspect 108:1179-1187 (2000). [Online 15 November2000]

http://ehpnet1.niehs.nih.gov/docs/2000/ 108p1179-1187clarke/abstract.html

Epidemiologic studies have associated human morbidity and mortality with exposure to ambient air particles (1-4). Toxicologic responses to particle exposures include acute mortality (5), histopathologic changes in the airways (6,7), increased airway hyperresponsiveness (7-9), pulmonary inflammation (10-15), and depressed pulmonary defense mechanisms (16-19). Particle mass, composition, and size have all been cited as modulators of these responses. However, these animal studies have been performed using ambient particle surrogates, including fly-ash, acid sulfate aerosols, silica particles, iron oxide, or carbon, which may not be representative of ambient particle exposures.

Recent technological advances have made it possible to directly expose animals to concentrated ambient particles (CAPs). These methods include the Harvard ambient particle concentrator (HAPC) and the New York University concentrator (20). Studies using the HAPC have shown that CAPs exposures are associated with significant alterations in breathing patterns and acute inflammatory responses marked by neutrophil influx and increased vascular permeability in normal and chronic bronchitic rats (22,23). Gordon et al. (24) failed to find pulmonary responses but reported hematologic changes in rats, including elevated levels of polymorphonuclear leukocytes, after exposure to New York City CAPs. These initial studies illustrated detrimental effects of CAPs and indicated the utility and complexity of using CAPs in studies of particle effects. …

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