Pulmonary carcinogenicity of repeated inhalation exposure of rats to aerosols of {sup 239}PuO{sub 2}
- Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM (United States); and others
To study the long-term biological effects of repeated inhalation exposure to {sup 239}PuO{sub 2}, 84-day-old rats were exposed to aerosols of {sup 239}PuO{sub 2} to re-establish desired {sup 239}Pu lung burdens of 26, 80 or 250 Bq every other month for 1 year (seven exposures). Other rats were exposed once at 84 or 450 days of age to achieve desired initial lung burdens of 30, 90, 280 or 850 Bq. The incidences of lung tumors were not significantly different (Fisher`s exact test; P > 0.05) in groups of rats with similar lifetime mean {alpha}-particle doses to the lungs of 0.90 {+-} 0.39 to 4.4 {+-} 1.8 ({+-} SD) Gy, whether exposed once or repeatedly. Among rats with mean {alpha}-particle doses of 12 {+-} 2.4 to 10 {+-} 2.1 Gy to the lungs after single or repeated exposures, respectively, the crude incidence of lung tumors was significantly less (Fisher`s exact test; P < 0.05) in the rats exposed repeatedly. Times of death of rats with lung tumors were compared among groups with similar {alpha}-particle doses to the lungs after single or repeated exposure to {sup 239}PuO{sub 2}. Those that died with lung tumors after repeated exposures died at times similar to (Mantel-Cos statistic; P > 0.05) or later than (Mantel-Cox statistic; P < 0.05) those for 84-day-old rats exposed once. The risk of lung tumors in rats per unit dose to the lungs was less in the rats exposed repeatedly than in those exposed once. It was concluded that {alpha}-particle doses to the lung of rats exposed repeatedly to aerosols of {sup 239}PuO{sub 2} were not more carcinogenic and possibly were less carcinogenic than the dose after a single inhalation exposure when rats with similar lifetime {alpha}-particle doses to the lungs were compared. The relative biological effectiveness in rats of the {alpha}-particle dose to the lungs from inhaled {sup 239}PuO{sub 2} relative to {beta}-particle doses to the lungs from inhaled {sup 144}CeO{sub 2} was 21 {+-} 3. 49 refs., 8 figs., 8 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 86330
- Journal Information:
- Radiation Research, Vol. 142, Issue 1; Other Information: PBD: Apr 1995
- Country of Publication:
- United States
- Language:
- English
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