However, in clinical studies, CAP effects as determined by analysis of blood/plasma markers and constriction of arteries have been readily apparent ( Ghio et al. Moreover, there is a lack of correlation between health end points and PM mass or its causative components ( Clarke et al. One of the limitations of this approach, however, is that the physicochemical properties of CAP and ambient PM may differ because the overall enrichment of CAP may depend on the size of incoming particles.Ī review of animal toxicologic studies involving CAP exposures has shown inconsistencies, and generally subtle health effects. This approach allows mechanistic characterization of PM effects and identification of causative constituents. 1995), allowing toxicologic studies to be conducted at higher than ambient concentrations.
Real-time ambient particle concentrators are designed to concentrate ambient particulate matter (PM) ( Gordon et al. These studies demonstrate a pattern of rat strain–specific pulmonary and systemic effects that are not linked to high mass but appear to be dependent on CAP chemical composition.Ī number of studies have recently reported pulmonary and cardiovascular health effects of concentrated ambient particles (CAP) in animals and humans ( Clarke et al. Biologic effects were evident in those six studies. Despite low chamber mass in the last six of seven 2-day exposure studies, the levels of zinc, copper, and aluminum were enriched severalfold, and organic carbon was increased to some extent when expressed per milligram of CAP. No biologic effects correlated with CAP mass. Significant correlations were found between CAP mass (microgram per cubic meter) and sulfate, organic carbon, or zinc. Inspiratory and expiratory times increased in SH but not in WKY rats. SH rats demonstrated a consistent increase of lavage fluid γ -glutamyltransferase activity and plasma fibrinogen. Except in the first study when CAP concentration was highest, lavageable total cells and macrophages decreased and neutrophils increased in WKY rats. The exposure concentrations varied among the seven 2-day exposure studies. Despite consistent and high CAP concentrations in the 1-day exposure studies, no biologic effects were noted. In seven 2-day exposure studies in 2001, SH and Wistar Kyoto (WKY) rats were exposed to filtered air or CAP (≤ 2.5 μm, 144–2,758 μg/m 3) for 4 hr/day × 2 days (analyzed 1 day afterward). In 2000 we conducted six 1-day exposure studies where spontaneously hypertensive (SH) rats were exposed to filtered air or CAPs (≤ 2.5 μm, 1,138–1,765 μg/m 3) for 4 hr (analyzed 1–3 hr afterward). Several studies have reported health effects of concentrated ambient particles (CAP) in rodents and humans however, toxicity end points in rodents have provided inconsistent results.
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