Repeated inhalation exposure of rats to aerosols of 144CeO2. I. Lung, liver, and skeletal dosimetry.
To develop a better understanding of the influence of cumulative radiation dose and dose rate to the lungs on the biological responses to inhaled radionuclides, several studies are in progress at this institute in which laboratory animals have been exposed once or repeatedly to aerosols of insoluble particles containing 144Ce or 239Pu. In the study reported here, F344 rats were exposed repeatedly to aerosols of 144CeO2 beginning at 94 days of age to reestablish desired lung burdens of 1.9, 9.2, 46, or 230 kBq of 144Ce every 60 days for 1 year (seven exposures). Other 94-day-old rats were exposed once to achieve similar desired initial lung burdens of 144Ce. Older rats were exposed once to achieve desired initial lung burdens of 46 or 230 kBq when 500 days of age, the age of the repeatedly exposed rats when exposed for the last time. Control rats were either unexposed, sham-exposed once or repeatedly, or exposed once or repeatedly to stable CeO2. Approximately equal numbers of male and female rats were used. The cumulative beta-radiation doses to the lungs, liver, and skeleton of rats exposed repeatedly were similar to those of rats with similar total lung burdens of 144Ce from a single inhalation exposure. The average beta-radiation dose rate to the lungs of the rats exposed repeatedly was about one-fifth of that in rats with similar total lung burdens after a single exposure.
Lundgren
D L
DL
Inhalation Toxicology Research Institute, Lovelace Biomedical and Environmental Research Institute, Albuquerque, New Mexico 87185.
Hahn
F F
FF
Diel
J H
JH
Snipes
M B
MB
D000336:Aerosols; D000818:Animals; D001610:Beta Particles; D001842:Bone and Bones / Q000378:metabolism*; D002563:Cerium / Q000008:administration & dosage; D002565:Cerium Radioisotopes / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005260:Female; D008099:Liver / Q000378:metabolism*; D008168:Lung / Q000378:metabolism*; D008297:Male; D011829:Radiation Dosage; D051381:Rats; D011916:Rats, Inbred F344; D013997:Time Factors
D000336:Aerosols; D002565:Cerium Radioisotopes; D002563:Cerium; C030583:ceric oxide