27 Results of the analyses indicate that 90¢,. and 137cs are dominant in the terrestrial environment and, in addition, 241Am and 239,240Py are also important in the soil from Bikini and Rongelap atolls. Cobalt-60 and °°Fe are predominant in the marine environment together with naturally occurring 40k. Amounts of radioactivity vary between atolls and between islands within an atoll] in relation to the distance from the test sites. Bikini atoll has the highest amounts of radioactivity, but the northern islands of Rongelap Atol] have only slightly lower amounts. Rongerik and Ailinginae atolls and the southern islands of Rongelap Atoll have similar amounts of radioactivity which are lower than Bikini by factors of 5 to 10 or more. Values at Utirik Atoll are lower stil], but are higher than amounts at Wotho and Kwajatein atolls. Christmas Island in the Line Islands has the Teast amount of radioactivity of the areas surveyed for this report. Radioactivity on Bikini and Rongelap atolls has declined significantly with time and should continue to do so due to physical and biological processes.