Synergistic interaction of nitrogen dioxide and ozone on rat lungs: acute responses.
Gelzleichter-TR; Witschi-H; Last-JA
Toxicol Appl Pharmacol 1992 Sep; 116(1):1-9
The synergistic interaction between nitrogen-dioxide (10102440) and ozone (10028156) was investigated in Sprague-Dawley-rats. Rats were exposed for 6 hours per day for 3 days to ozone (0.2 to 0.8 parts per million (ppm)), nitrogen-dioxide (3.6 to 14.4ppm), or combinations of both oxidant air pollutants. Responses were quantified by changes in total protein content of lung lavage supernatants or by alterations in the content of specific cell types in lavage pellets. Results revealed a concentration dependent synergistic response upon combined exposure. Concurrent exposure was necessary to elicit positive interaction which is a greater than additive response. No positive interactions were seen when rats were exposed sequentially to ozone or nitrogen-dioxide. Given the apparent disappearance rates of ozone during combined exposure, predicted outcomes were modeled on the assumption that ozone and nitrogen-dioxide were reacting in the chambers to form nitrogen-pentoxide. The authors conclude that synergistic toxicologic interactions between ozone and nitrogen-dioxide are found only at concentrations much higher than would be found in environmental or occupational settings. The potential for chronic toxicological responses with levels below those causing acute responses requires further investigation.
Laboratory-animals; Nitrogen-oxides; Lung-cells; Protein-chemistry; Synergism; Environmental-pollution; Combustion-gases; Toxic-gases
Toxicology and Applied Pharmacology
University of California - Davis