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Chromosome damage in rat pulmonary alveolar macrophages following ozone inhalation
K Rithidech1, J A Hotchkiss, W C Griffith
1Inhalation Toxicology Research Institute, Lovelace Biomedical and Environmental Research Institute, Albuquerque, MN 87185.
Abstract:
To determine whether ozone is clastogenic at environmentally relevant exposure levels, rats were exposed for 6 h to 0.0, 0.12, 0.27, or 0.80 ppm ozone. The alveolar macrophages were isolated from animals sacrificed 28 h after the end of the exposure. The mitotic index and frequency of chromosome aberrations were determined. No change in the mitotic index was detected following 0.12 ppm ozone exposure. A significant decrease in mitotic index was observed after exposure to 0.27 ppm ozone; a significant (4-fold) increase in the frequency of dividing macrophages was detected following exposure to 0.8 ppm ozone. Only chromatid-type aberrations were observed. There was a significant increase in the frequency of cells with chromatid gaps and in the frequency of cells with chromatid deletions. Animals exposed to 0.27 ppm ozone had the highest proportion of cells with chromatid deletions (0.172) relative to background level (0.028). No exchanges or chromosome-type aberrations were detected in any of the animals. These data suggest that ozone, at relatively low levels, is clastogenic in macrophages from exposed rats.
Insights
Ozone exposure, even at low environmental levels, can cause genetic damage in rat macrophages. This study found ozone is clastogenic, increasing chromosome aberrations in these cells.
Area of Science:
- Environmental Toxicology
- Genetics
- Cell Biology
Background:
- Ozone is a major air pollutant with potential health effects.
- Understanding ozone's genotoxicity is crucial for public health risk assessment.
Purpose of the Study:
- To investigate the clastogenic potential of ozone at environmentally relevant concentrations.
- To assess ozone-induced chromosome aberrations in rat alveolar macrophages.
Main Methods:
- Rats were exposed to varying ozone concentrations (0.0-0.80 ppm) for 6 hours.
- Alveolar macrophages were isolated 28 hours post-exposure.
- Mitotic index and chromosome aberration frequencies (gaps, deletions) were analyzed.
Main Results:
- Ozone exposure at 0.27 and 0.80 ppm significantly affected the mitotic index.
- A significant increase in chromatid gaps and deletions was observed, particularly at 0.27 ppm.
- No chromosome-type aberrations or exchanges were detected.
Conclusions:
- Ozone demonstrates clastogenic activity in rat macrophages at low, environmentally relevant exposure levels.
- Chromatid aberrations are the primary type of genetic damage induced by ozone.
- These findings highlight potential cellular mechanisms of ozone toxicity.