THE NORTHERN MARSHALL ISLANDS RADIOLOGICAL SURVEY: | TERRESTRIAL FOOD CHAIN AND TOTAL DOSES ABSTRACT A radiological survey was conducted from September through Novemberof 1978 to assess the concentrations of persistent manmade radionuclides in the terrestrial and marine environments of |! atolls and 2 islands in the Northern Marshall Islands. The survey consisted mainly of an aerial radiological reconnaissance to map the external gamma-ray exposure rates over the islands of each atoll. The logistical support for the entire survey was designed to accommodate this operation. As a secondary phase of the survey, shore parties collected appropriate terrestrial and marine samples to assess the radiological dose from pertinent food chains to those individuals residing on the atolls, who may in the future reside on some of the presently uninhabited atolls, or who collect food from these atolls. Over 5000 terrestrial and marine samples were collected for radionuclide analysis from 76 different islands. Soils, vegetation, indigenous animals, and cistern water and groundwater were collected from the islands. Reef and pelagic fish, clams, lagoon water, and sediments were obtained from the lagoons. 24) Here we summarize the concentration data for 905, 13766, 23854, 239+2405, and Am in terrestrial food crops, fowl, and animals collected at the atolls or islands. We also provide an assessment of the total dose from the major exposure pathways including external gamma, terrestrial food chain including food products and drinking water, marine food chain, and inhalation. Radiological doses at each atoll or island are calculated from the average radionuclide concentrations in the terrestrial foods, marine foods, etc. assuming the average daily intake for each food item. The terrestrial food chain is the most significant exposure pathway--it contributes more than 50% of the total dose--and external gamma exposure is the second most significant pathway. Other pathways evaluated are the marine food chain, drinking water, and inhalation. Cesium-137 produces more than 85% of the predicted dose, 995, is the second most significant radionuclide, and the transuranic radionuclides contribute a small portion of the total predicted lung and bone doses.