~2~ these lesions in the Marshallese and Americans exposed have been documented (Gonard et al.) and will be referred to frequently in thie chapter. Lesions of the skin induced by fallout are primarily due to the beta raGliation from the fission products adhering to the fallout material and are, therefore, frequently referred to as beta burns. So-called beta burns of the skin may also result from accidental exposure to, or contamination with, radioisotopes used in science and industry. The possibility of such accidents mst be considered seriously in view of the increasingly widespread use of radioisotopes. —_ 2 FALLOUT SITUATIONS RESULTING IN SKIN DAMAGE. With detonation of molear devices, serious radiation injury to the skin is only associated with fallout situations where the radioactive material is sufficiently concentrated. Such concentrations are most likely to occur with close-in fallout, 1.¢., fallout that occurs within several hundred miles of the detonation. It seems probable that the fallout will be visible if serious acute skin damage ia to result; however, this cannot be stated with certainty. In the Marshall Island accident, the extent and severity of the skin lesions were directly correlated with the amount of visible fallout. On the most dis- tant of the contaminated islands, some 200 miles from the site of detonation, the fallout was not visible and no beta lesions of the akin developed among the inhabitants. The world-wide deposit of fallout which occurs slowly from the troposphere or stratosphere does not result in skin injury since in this situation the fallout material is greatly diluted and reduced in amount, Demage to the skin such as that seen with beta radiation does not result from the immediate penetrating gamma or neutron radiation associated with detona4on of moclear devices since the dose of such radiations necessary to severely