Prge i ee APPENDIX E FEASIBILITY OF ESTIMATING BODY STRONTIUM BURDEN BY ANALYSIS OF MILK AND URINE By Roy E. Albert, M. De It would be highly desirable, in the event of wideespread dissemination of radioactive strontium, to have a reliable method of monitori NE, this hazard in large populations. Radioactive strontium is capable bf producing bone tumors in animals. Its toxicity for man is dependen by analogy on the same property. Since the latent period is presum ty to be in the same order as that for radium, persons under 35 would undergo the major risk and particularly those in the stage of activ bone growth. Strontium wuld reach the bone only, except in unusua cases, by intestinal absorption. Consequently, the main source of danger would exist in polluted food and water. The strontium is concentrated in plants which are in turn consumed by dairy animals secreted in milk. Milk products would therefore be a major carrier this toxic agent. The metabolism of strontium is qualitatively Similar to that of calcium and consequently the uptake of strontium would come from foods with high calcium contents. The minimum dail requirement of calcium in adults is 0.5 grams and probably double tis for growing children. Each quart of milk contains 1.2 grams of calcium and consequently milk or its products can supply most of the calcium needs. However, a number of vegetables contain sufficient strontium to account for a significant percentage of the daily requirements. The most direct method of determining the potential hazard from rad: active strontium is to measure the amounts in enough human bone of various ages to give a reasonable estimate of bone burden for the population. This, of course, has its practical difficulties. Anot er approach would be to obtain a cross section of the milk and milk product contamination but the relationship hetween rates of radioactive strontium ingestion and rates of accumulation in the skeleto would nave to be determined in humans, Still another approach woul involve estimation of specific activity of strontium in blood, urin or milk in the population. The latter two would be easiest to coll ct in a pooled sample, especially urine, and would provide a convenien monitor if the relationship between radioactive strontium excretion and body burden could be established. The purpose of this report i to assess the data available in the literature in order to determin whether and under what conditions this relationship exists. -88-