X. RADIOLOGICAL MONITORING OF PERSONNEL AND ENVIRONMENT Radiological monitoring of personnel and environment of the islands affected by the 1954 fallout accident is reviewed in detail in Appendix II (Dose Assessment) and in the 20-year report (1). The findings will only be briefly summarized here. A. Background The medical team assumed responsibility for the personnel monitoring of the Rongelap and Utirik people in 1954 and for that of the Bikini people returning to live on their home island in 1969. In 1978, both environmental and personnel monitoring responsibilities were transferred from the Medical Department to the Safety and Environmental Protection Division of this Laboratory. Numerous radiological surveys for environmental contamination have been carried out on Rongelap, Utirik, Bikini, and Enewetak (210-225). These studies have provided important information on the movements of radionuclides through marine and terrestrial life to man and have aided in the evaluation of the body burdens of radionuclides in the inhabitants of these islands. B. Methods Methodology for personnel monitoring has been discussed in detail in pre- vious reports (8,18,22). Personnel monitoring has consisted of regular radiochemical analyses of urine specimens from inhabitants along with wholebody gamma spectrographic analyses for gamma emitters with special shielding arrangements (first a 21l-ton steel room and later a "shadow-shield" bed and chair arrangement of lead bricks). C. Results and Comments 1. Rongelap and Utirik The radionuclides absorbed at the time of the fallout from consumption of contaminated food and water and inhalation are tabulated for the Rongelap people in Table 2 of Appendix II. Only radioiodines were absorbed to above acceptable levels. The full impact of the thyroid injury resulting from absorption of radionuclides of iodine was not appreciated until much later when development of thyroid nodules and stunting of growth in some of the children occurred. As discussed in Appendix II, the dose calculations for the thyroid have been subject to many uncertainties and can only be considered approxi- mate. The absorption of radionuclides other than iodine has not resulted in any detectable injury, and the doses to the target tissues from these radio- nuclides are thought to have been quite low though no precise doses have been calculated. By six months, radiochemical urine analyses revealed barely detectable levels of radionuclides in the Rongelap people. When they returned to their - 82.-