relatively large ranges in values were found for the individual isotopes in the plants and animals. Any conclusions, therefore, must be of only the most tentative and generalized nature. " The data do suggest that in terms of strontium-90, the isotope of principal concern, this activity built up in the plant life over the first year after fallout and then started decreasing slowly. By using very rough approximation, and extrapolations, the data suggest that if plant life had been growing in the area of highest contamination it might have contained 10-30 microcuries of strontium-90 per kilogram of calcium, at one year. higher. The corresponding values for the soils are several times If an assumption is made that there is a discriminatory factor of about four for the Sr/Ca ratio in plants versus bones, the above data suggest possible levels of strontium-90 in the bones of animals from continuous consumption of this food of a few to several microcuries. of strontium-90 per kilogram of calcium. The maximum permissible body burden for adult atomic energy workers is one microcurie of strontium90 per kilogram of calcium. There is some confirmatory evidence for this crude evaluation. A variety of mative animals were left on the Island of Rongelap after the fallout in March 1954. serially in time. They have been collectad and sacrificed Even after two years of continuous occupancy it was reported that there were no pathological changes that could be ascribed to radiation.22 Their bones showed from about a one-tenth to a few tenths of a microcurie of strontium-90 per kilogram of calcium. Since the areas of highest contamination were about 12-14 times greater than Rongelap, — -~1g- —sN