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A chronic inhalation toxicity study of diesel engine emissions and coal dust, alone and combined.

Lewis-TR; Green-FH; Moorman-WJ; Burg-JR; Lynch-DW
J Amer Coll Toxicol 1989; 8(2):345-375
A long term study of the effects of inhalation exposure to diesel engine emissions and coal dust, both alone and combined, was designed to be conducted over a 2 to 3 year period using male and female weanling Fischer-344-rats and 60 male cynomolgus-monkeys. The mutagenic activity of the two sources of particulate were investigated using gene mutation and cytogenetic assays. The results indicated that diesel exhaust at airborne concentrations of 2mg/m3 was more hazardous to the health of the animals than the same concentration of respirable coal dust. Gross and histopathological evidence both suggest that particles from each source were deposited and retained in pulmonary alveolar tissues. In both exposures the defense mechanisms of the lung against infectious diseases were altered even though no alteration was noted in the membrane integrity of alveolar macrophages. Coal dust activated phagocytosis by alveolar macrophages while diesel exhaust depressed phagocytosis. The number of macrophages obtained by lavage were increased in response to coal dust while at the same time the secretion of reactive forms of oxygen was enhanced, and increases were noted in the cellular surface area. Diesel exhaust decreased secretion of reactive forms of oxygen and diminished the surface ruffling. The combined exposures resulted in degrees of secretory activity and surface morphology which were intermediate between the effects of separate exposures. Increases in oncogenicity were negative in rats and no evidence of treatment induced tumorigenicity was found in the monkeys.
NIOSH-Author; Bioassays; Pulmonary-system-disorders; Alveolar-cells; Cell-damage; Inhalation-studies; Dust-inhalation; Diesel-engines; Coal-dust; Diesel-emissions; Laboratory-animals
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Journal of the American College of Toxicology