Nature and Extent of Internal Radioactive Contamination of Human Beings, Plants, and Animals Exposed to Fallout

摘要

The first instance of exposure of human beings to mixed fission products occurred as a result of the contaminating detonation of 1 March 1954. Beta activity in the urine of these exposed human beings indicated significant internal contamination from the ingestion and inhalation of fallout material. The body burden of the group of human beings with the greatest internal contamination was of the order of the maximum permissible concentrations for the individual radionuclides. Few of the fission products present in the environment were readily absorbed by the bloodstream from the lungs and the gastrointestinal tract. Most of those radioelements that gained entry into the body had short radiological and biological lives, and thus the levels of activity in the tissues of the body were relatively low. The concentration of radioisotopes at 6 months postdetonation was barely detectable in the urine of most of the exposed individuals. The human body burden of individual radionuclides was estimated from radiochemical analysis of the human urine and of the tissues and urine of animals from Rongelap. The mean body burdens of the radionuclides in the Ailinginae group were approximately one-half those of the Rongelap group, and the mean body burdens of the American group were about one-fourth those of the Rongelap group.