opiseettt aeeESAIM LOSE, - pesure under extreme conditions, with no correc: Uve measures taken to reduce internal abserption of radioisotopes prior ta evacuationof the exposed people fromthe fallout area. It did not involve the contaminated pasture-cattle- milk cyele, which Iivht be an important pathway of radioiodine to tan in other types of accidents (such as the Wind- scale accident). !74 Civil Defense planning can provide for several tueasuces that will rechuce the hacard af thyroid exposure due to radigiodine absorption and thus largely preclude the degree of thyroid tajury sustuined by the Marshallese. Since Che hazard fromm radiviadine is acute for a pertad only of days, carly protective measures are extremely tinportant. Vhese inchude avoiding tibalation of radio- todines by shelter protection, Cousumung food and water only from closed containers; feeding cows in contaminated areas protected fodder; and tem- purarily withholding contaminated milk supplies and diverting them inte processed products with a shelf life longer than the life of the isotope. The addition of stable iodine to food or water dur- ine the first week waulld provide a relatively inex. pensive method of reducing thvroid uptake of radioiodines by isotope dilution and saturation with non-radioactive todine: this should rarely prodlace any serious side cHeets and would be of partier value in children and pregnant women, When exposure of the thyroid bas already occurred, prophylactic eatment with thyroid hormone, now beige used in the Marshallese, may help prevent development of thyroid tumors, and even after tamer development, surgical excision Inay reduce jortality duc to nnidigaaney, ‘Phe Uivroid effects in the Marshallese were not anticipated at the tine al the accident or during the earky veags aflenwards. bi retrospect this is not surprising, for several reasons. Nt that time the thy. raid was thought to be relatively racioresistant, particubirly with regard to radioiodine esx posure ton the basis of inaat studies and diagnaste and therapeutic useof FUP ia people. and the calou- lated thyroid doses inthe Mtarshallese were con: sidered to be below the levels ikely to produce humors, Fadditon, neither the iapartince of the exposure to short-lived todine ieatopes ta fallous nor the divroid dose ciilerential in children due to the smaller size of their ghind wis fully appreciated, Tas quite likely thatthe Gaal cesulis of thyroid lesions inthe Marshallese are dacomiptere at this lime since new desions are sail occurring. “The . " htt, inean latent period for radiation-induced thyroid tumors may be as long as 30 years. Cases have becn scen as late as 40 years after exposure. Furthermore, on the basis of the present data the risk of developing radiation-induced thyroid neoplasia is probably underestimated, since surgical removal of potentially malignant tissues may have occurred and the hormone treatment mayhave inhibited the development of some tumors, although the latter is questionable, As has been pointed out, also, the true carcinogenic potential of the exposure, particularly in the children receiving the higher duse, may have been masked byexcessive cellular destruction. The recent finding that subclinical thyraid deficiency is present in sume of the ex- posed people who have not shown anythyroid abnormalities indicates that the thyroid effects in the Marshallese may nat vet be completely manifest, and continued careful surveillance of this populalon Is necessary. Acknowledgments Because of the broad scape of the surveys and the complexity of operations it would be impossible to acknowledge all the individuals and organ- ations that have contributed to the success of the surveys over the past 20 sears. We would fike, however, to express thanks to some who have contributed vitally in more recent vears. Our foremost appreciation is to the people of Rongelap and Utirik who have participated in the cxaninations, including the unexposed people comprising the control population, We treasure the friendship and trust of these people. We are grateful ta many Rongelap and Ciirik people for assisting: the examining teams over the vears, inchiding the Magistrates of both istands - a1 Ronvelap: John Anjain, Billicr Kdmond. fabwe Jorju. and Nikunmos Antak: at Girik: KRabto Campus, Maja Lena, Harold. the school principal. and Joata. the health aide. ‘Phe senior author is most grateful to the many fine medical anc other specialists (listed in Appendix 2) who have so willingly given of their time and talents, without remuneration, to participate in the surveys. Without their dedicated efforts the surveys could never have succeeded. Fle is also greatly indebted to the many technical assistants who have conmibuted nnueh to the success of the surveys, particuaily to Mr. W. Seott and Mr 1D.