Biological Half-Life Studies of Tritium in Chronically Exposed Kangaroo Rats

The biological half-life of tritium was measured in the body water and in brain, liver, lung, kidney, heart and muscle tissues of two groups of kangaroo rats captured in the tritiated environment at Sedan Crater in the Nevada Test Site. These animals had been exposed to tritium in their natural food for their entire lifetime. The rodents were maintained on tritium-free food in the laboratory during the two study periods of five and nine months. At regular intervals, several animals from each group were killed, dissected and lyophilized. Tritium in the body water was determined by liquid scintillation counting. Dried tissue residues were assayed by sealed-flask combustion and liquid scintillation counting. The biological half-life of tritium in the tissue compartment of these uniquely exposed animals was 1.5 to 4 times that of the body water. At the time of trapping, a slight enrichment of tritium in tissue was indicated by the initial ratio of tissue to body water tritium which ranged from 1.2 to 1.6 with an average value of 1.40 ± 0.14.