Short-term exposure of rodents to diesel exhaust: usefulness for studi es of genotoxic and immunotoxic effects

An exposure facility was tested with regard to information obtainable form short-term animal experiments for the assessment of health haza rds from automotive engine exhaust. Indicators of immunotoxicity and genotoxicity were studied in guinea pigs and mice, respectively, for 2 weeks, 8 h/day, to ten times diluted exhaust from a one-cylinder re search engine running at constant load. Regulated and non-regulated p ollutants were determined. Besides increased number of lavageable cel ls in the airways, exposed guinea pigs exhibited, after immunization and challenge to ovalbumin, reduced leukotrienes B4 and C4 in lavage fluid and reduced anti-ovalbumin IgG in serum. Absence of increased C YP1A activity indicated that the exposure was below the thres hold for induction of these enzymes. Instead a certain reduction in th is acti vity indicated interaction with active enzyme sites. In vivo doses of some reactive metabolites of low molecular mass were measured by add ucts to hemoglobin. Doses from alifatic epoxides were low, in accorda nce with low hydrocarbon levels in the exhaust. The levels of hemoglo bin adducts from aldehydes showed no clearcut influences of exposure. Genetic effects determined by DNA fingerprint analysis were i ndicate d. It is concluded that repeated dose inhalation exposure of small nu