Radioactive contamination in the Marshall Islands

Researchers report measurements of radioactive contamination from nuclear weapons testing in the Marshall Islands. The United States conducted 67 nuclear weapons tests on Enewetak and Bikini Atolls, part of the Marshall Islands, between 1946 and 1958. The tests exposed islands in these and neighboring atolls to high levels of fallout, causing environmental contamination and long-term adverse health effects for the islands' inhabitants. In a series of studies, Malvin Ruderman, Emlyn Hughes, and colleagues assessed the current extent of radioactive contamination in 4 atolls in the northern Marshall Islands: Bikini, Enewetak, Rongelap, and Utirik. External gamma radiation was significantly elevated in Bikini Atoll, on Enjebi Island in Enewetak Atoll, and on Naen Island in Rongelap Atoll, compared with a control island in the southern Marshall Islands. External gamma radiation on Bikini and Naen islands exceeded the maximal exposure limit established in a memorandum of understanding between the United States and the Republic of the Marshall Islands. High activity concentrations of certain radioactive isotopes were observed in soil samples from Runit and Enjebi Islands in Enewetak, as well as from Bikini and Naen Islands, in some cases exceeding levels found in areas affected by the Fukushima and Chernobyl nuclear disasters. In a second study, Ruderman, Hughes, and colleagues mapped radioactivity levels of isotopes in ocean sediment from the Castle Bravo crater at Bikini Atoll, formed by the largest US nuclear weapon test. Activities of several isotopes--239, 240Pu , 241Am, and 207Bi--throughout the crater were at least an order of magnitude higher than those found in sediments elsewhere in the Marshall Islands. In situ measurements of radioactive 137Cs levels in coconuts and pandanus fruits from 11 islands revealed that a sizeable fraction of fruits from Bikini and Rongelap Atolls had radioactivity levels exceeding the limits set by several countries and international organizations. Contamination was especially high on Bikini Island, where some fruits exceeded even the highest safety limits. The results have implications for resettlement of the affected islands, according to the authors.

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Article #19-03421: "Background gamma radiation and soil activity measurements in the northern Marshall Islands," by Maveric K.I.L. Abella, Monica Rouco Molina, Ivana Nikoli?-Hughes, Emlyn W. Hughes, and Malvin A. Ruderman.

Article #19-03478: "Radiation maps of ocean sediment from the Castle Bravo crater," by Emlyn W. Hughes, Monica Rouco Molina, Maveric K.I.L. Abella, Ivana Nikoli?-Hughes, and Malvin A. Ruderman.

Article #19-03481: "In situ measurement of cesium-137 contamination in fruits from the northern Marshall Islands," by Carlisle E.W. Topping et al.

MEDIA CONTACT: Malvin A. Ruderman, Columbia University, New York, NY; tel: 212-854-3317; e-mail: mar@astro.columbia.edu; Emlyn W. Hughes, Columbia University, New York, NY; tel: 212-854-0796; e-mail: ewh42@columbia.edu