In any groundwater case, are at all below atolls the 90 Sr the concentration 137 Cs and guidelines concentrations for drinking in water recommended by the Environmental Protection Agency. The maximum calculated for the the atolls. and annual dose and the 30- and 50-y integral doses are intake of both cistern water and groundwater for each of Doses from the Enieatok rates Islands are ingestion of cistern water at less than 0.1% (0.001) guidelines and the 30-y guideline; doses at of Bikini, the Rongelap, individual annual the other atolls are about 0.01% of the guidelines. Even if situation) the total annual consumption were groundwater (an unrealistic the estimated doses at Rongelap and Utirik are about 0.3% of the guidelines and less than 0.1% for the other atolls. We conclude preferred that the cistern water, water sources contribute at a very the small atolls, especially fraction of the the estimated total doses from all exposure pathways. INTRODUCTION A radiological survey was conducted from September through November of 1978 to assess the concentrations of persistent man-made radionuclides in the terrestrial and marine environments of 11 atolls and 2 islands of the Northern Marshall Islands. Rongelap, Mejit, specific Utirik, Wotho, The atolls Taka, Bikar, Ujelang, islands of and and Bikini islands Rongerik, Bikini. Atoll are shown Ailinginae, Concentrations have been well in Fig. 1 Likiep, of and include Jemo, Ailuk, radionuclides documented./~4 on However, little radiological information is available for the remainder of the atoll or for other atolis that were considered most from nuclear tests conducted at likely to have received fallout the Pacific Proving Grounds between 1946 and 1958. The survey consisted, in part, of an aerial radiological reconnaissance to map the external gamma-ray exposure rates over the islands of each atoll. Shore parties the the collected appropriate terrestrial and marine samples radiological dose atolls, or who from pertinent may in the food chains future reside to assess to individuals residing on on some of the uninhabited atolls, or who may now collect food from these atolls. presently