title: Partition of thorium between organs of monkeys injected with thorotrast: implications for alpha-particle dosimetry.
abstract: Risk estimates for alpha-particle-induced malignancies have been based mainly on studies of Thorotrast patients, but certain aspects of its deposition in the body have been at issue: the partition between the liver, spleen and red bone marrow, and the deposition at lower concentrations in other organs, such as muscle and fat, which may contribute to the risk. To supplement the existing data for humans, thorium concentrations were measured in the organs of two female monkeys 3-4 years after injection with Thorotrast. Relative deposits (liver:spleen:red bone marrow) were 54:6:41 and 75:4:21, in better agreement with the most recent observations in Thorotrast patients than with previous reports. Whereas the human testis had ranked among intermediate-level organs such as the adrenal glands and pancreas, the ovary of the monkey was among the organs with the lowest concentrations. The data suggest that risk factors for induction of malignancies by alpha-particle irradiation should be re-examined.
authors.affiliation: Department of Pathology, The Cancer Institute, Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Ishikawa
authors.forename: J A
authors.initials: JA
authors.lastname: Humphreys
authors.forename: H
authors.initials: H
authors.lastname: Wesch
authors.forename: N D
authors.initials: ND
authors.lastname: Priest
mesh_terms: D000818:Animals; D002273:Carcinogens / Q000493:pharmacokinetics*; D005260:Female; D008252:Macaca fascicularis; D013910:Thorium / Q000378:metabolism*; D013911:Thorium Dioxide / Q000493:pharmacokinetics*; D014018:Tissue Distribution
chemical_list: D002273:Carcinogens; D013910:Thorium; D013911:Thorium Dioxide