From 1945 to 1980, over 500 weapons tests were conducted in the atmosphere at a number of locations around the world. These tests resulted in the release of substantial quantities of radioactive debris to the environment. Local, intermediate, and global fallout deposition densities downwind from test sites depended on the heights of bursts, the yields, and the half-lives and volatilities of the particular fission or activation products, as well as on the meteorological conditions. A number of national and international monitoring programs were established to trace the fallout through the atmosphere and biosphere. These programs included continuous monitoring of ground-level air, exposure rates, and deposition as well as periodic sampling of food, bone, water, soil, and stratospheric air. Although data for specific high-yield tests are still classified, the fission and fusion yields of the various tests and test series have been estimated and from this information the quantities of specific fission and activation products released into the atmosphere have been determined. The geographic and temporal variations in the fallout deposition of specific radionuclides based on both actual measurements and model calculations are discussed in this paper. A feasibility study to estimate the deposition density (deposition per unit area) of particular radionuclides from both Nevada Test Site and "global" fallout on a county-by-county scale for the continental United States is described. These deposition estimates provide a basis for reconstructing population exposure and dose. They support the feasibility of a more detailed evaluation of the population doses that resulted from fallout from atmospheric tests to document the experience fully and to report results more systematically and completely to the world community. The impact of weapons fallout will continue to be felt for years to come since a contaminant baseline has been imposed on the ambient radiation environment that will be an important factor in the assessment of past and future releases of radioactive materials into the biosphere.

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Aluminium is one of the most abundant elements in the environment and is released from both natural and anthropogenic sources. Representative values of aluminium concentrations in the background environment and in man are selected from available data and a pathway analysis is performed utilising the exposure commitment method. Using a derived estimate of the body burden (60 mg), a representative value for dietary intake (20 mg day-1) and fractional absorption of 0.01, a mean retention time of A1 in the body of 300 days is obtained. This corresponds to a biological half-time of 210 days. The assessment indicates that an average dietary intake rate of 20 mg day-1 contributes 660 micrograms kg-1 of aluminium to the body, while inhalation of aluminium in air makes, in comparison, a negligible contribution to the body content.