HEPATIC-EFFECTS OF INHALED PLUTONIUM DIOXIDE IN BEAGLES

The effects of inhaled (PuO2)-Pu-238 deposited in the liver of dogs we re studied in beagles exposed to initial lung depositions ranging from 5.7 to 2979.7 Bq/g lung. Approximately 20% of the initial lung deposi tion was translocated to the liver by 1500 days after exposure. Life-s pan observations revealed that the liver contained 40% of the final bo dy burden of plutonium, second only to the skeleton. Elevated serum li ver enzyme activities were observed in dogs with final liver depositio ns of greater than or equal to 0.4 Bq/g, cumulative dose to the liver of greater than or equal to 0.18 Gy and annual dose rate greater than or equal to 0.02 Gy/year. Enzyme elevations were seen at one dose leve l lower than that in which bone or lung tumors were observed. Linear r egression analysis revealed strong to moderate correlation between cum ulative dose and dose rate and time to observed increases in liver enz yme activities. Liver tumors were late-occurring neoplasms observed at lower exposure levels where life span was not shortened by lung and b one tumors. (C) 1995 by Radiation Research Society