Comparative study of the behaviour of strontium 89 in nonirradiated and in nonlethal X-ray-dose irradiated organisms

Selected aspects of radiostrontium kinetics in orally treated rats were studied under external exposure conditions, using intermediate level X-ray doses. Distribution of the radionuclide was estimated by measuring whole-body activity and femur activity over a period of two months after treatment. With 300 R X-rays, the rate of intestinal absorption of radiostrontium was found to exceed that in animals receiving no external exposure: body burdens were likewise higher in X-rayed animals. Such differences were noted within the first days post treatment but not at later times. With 100 R X-rays, there was a similar tendency to increased absorption and body burden; the differences, however, were not statistically significant. From analysis of the equations described removal of radiostrontium from the body, 30-day excretion rate was higher by a factor of 4 in rats exposed to 300 R X-rays compared to unexposed animals. Excretion occurred as a two-compartment process; there were no differences between externally exposed and unexposed rats in Tsub(ef2), with Tsub(ef1), however, shorter in X-rayed animals. As regards 60-day dose commitments to femur from radiostrontium, no differences were found between the two groups of rats. (A.B.)