Despite the fact the adequate data from long-term, chronic experiments on the effects of Po{sup 210} are not available, some sort of a working figure for the maximum permissible body content of polonium is desirable. As described herein, calculations involved in determining the permissible body content of polonium generally fall into three classes. 1. Comparison of X-ray and polonium toxicity and application of an acceptable X-ray tolerance figure. 2. Assumption of a most sensitive organ and computation of the critical concentration of radioactive material present in this organ under conditions such that the organ received an assumed maximum permissible exposure over an indefinitely long period of time. 3. Comparison of radium and polonium toxicity with application of an acceptable maximal content of radium.