'Fallout tritium' distribution in the environment

It is evident that fallout tritium has been incorporated into all hydrogen-containing materials throughout the biosphere. The tritiated water content, available by freeze drying (loose water fraction), and the additional tritium available by complete combustion (organic bound fraction) has been analyzed; in soil, vegetation, food, and animal and human tissues. Up until 1973 the tritium specific activity in the organic bound fraction is higher than that found in the loose water fraction. The ratio of specific activities decreased by a factor of 2 from each trophic level: soil 6 to 8, vegetation 3 to 4, and man 1.5 to 2. The lowest ratio observed in this study was 1.2 for the animal metabolite, milk. (author)