Thorium distribution behavior

Martin JM, Nijampurkar V, Salvation F (1978b) Uranium anti Thorium isotope behavior in estuarine systems. In Biogeochemistry of estuarine sediments. UNESCO, p 111-127 Mathieu D, Bemat M, Nahon D (1995) Short-lived U and Th isotope distribution in a tropical laterite derived from Granite (Pitinga river basin, Amazoitia, Brazil) application to assessment of weathering rate. Earth Planet Sci Lett 136 703-714... 

The distribution pattern of intravenously-injected Thorotrast in animals is similar to the pattern in humans most of the Thorotrast is taken up by the RES (Guimaraes et al. 1955 McNeill et al. 1973 Reidel et al. 1979). Reidel et al. (1979) determined that the average percent distribution of Thorotrast in the liver was within one order of magnitude in mice, rats, rabbits, dogs, and humans. The amount of thorium in the spleen of all species, except mice, was clearly below that in humans. Only 50% of the thorium in rats was retained in the liver and spleen, while approximately 85% was retained in humans. Direct comparison of the species is difficult, since the data were taken from other authors and analyzed by Reidel et al. (1979). The study concluded that the biological behavior of colloids was similar in humans and animals. Kaul and Heyder (1972) reported an extremely low rate of clearance of the colloid form from the blood about 1 hour after intravenous injection in rabbits. Subsequently, an increase in the rate of disappearance from the blood of the colloid form (biological half-life of 90 minutes) and of the soluble form (biological half-life of 75 minutes) was found. After 3, 6, or 12 hours, 23, 45, or 60% of the injected amount, respectively, was located in the liver. 

Both Pu and Th will probably enter the skeleton and other internal tissues predominantly from inhalation. This statement is based on the fact that in the field, Pu and Th demonstrate similar transfers from soil to small mammals and laboratory studies demonstrate similar metabolic characteristics (1,3,23). Soil chemical behavior is also similar (20). As demonstrated in Table I, natural Th in human bone originates largely from inhalation, even assuming that adsorption from the diet is 0.1%. Another strong agrument for the importance of inhalation is found in tissue distributions of Th-232 and Th-230 in humans. Table V summarizes work by Wrenn, et al. (53) which shows that lungs of non-occupationally exposed individuals contains burdens of Th isotopes comparable to the skeleton. Thorium-228 distributions are different from Th-230,... 

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