Measurement of background gamma radiation in the northern Marshall Islands.
We report measurements of background gamma radiation levels on six islands in the northern Marshall Islands (Enewetak, Medren, and Runit onEnewetak Atoll; Bikini and Nam on Bikini Atoll; and Rongelap on Rongelap Atoll). Measurable excess radiation could be expected from the decay of (137)Cs produced by the US nuclear testing program there from 1946 to 1958. These recordings are of relevance to safety of human habitation and resettlement. We find low levels of gamma radiation for the settled island of Enewetak [mean = 7.6 millirem/year (mrem/y) = 0.076 millisievert/year (mSv/y)], larger levels of gamma radiation for the island of Rongelap (mean = 19.8 mrem/y = 0.198 mSv/y), and relatively high gamma radiation on the island of Bikini (mean = 184 mrem/y = 1.84 mSv/y). Distributions of gamma radiation levels are provided, and hot spots are discussed. We provide interpolated maps for four islands (Enewetak, Medren, Bikini, and Rongelap), and make comparisons to control measurements performed on the island of Majuro in the southern Marshall Islands, measurements made in Central Park in New York City, and the standard agreed upon by the United States and the Republic of the Marshall Islands (RMI) governments (100 mrem/y = 1 mSv/y). External gamma radiation levels on Bikini Island significantly exceed this standard (P = <<0.01), and external gamma radiation levels on the other islands are below the standard. To determine conclusively whether these islands are safe for habitation, radiation exposure through additional pathways such as food ingestion must be considered.
K1 Project, Center for Nuclear Studies, Columbia University, New York, NY 10027; ICF International, Durham, NC 27713;
Autumn S
AS
Bordner
K1 Project, Center for Nuclear Studies, Columbia University, New York, NY 10027;
Danielle A
DA
Crosswell
K1 Project, Center for Nuclear Studies, Columbia University, New York, NY 10027;
Ainsley O
AO
Katz
K1 Project, Center for Nuclear Studies, Columbia University, New York, NY 10027;
Jill T
JT
Shah
K1 Project, Center for Nuclear Studies, Columbia University, New York, NY 10027;
Catherine R
CR
Zhang
K1 Project, Center for Nuclear Studies, Columbia University, New York, NY 10027; Department of Chemistry, Columbia University, New York, NY 10027;
Ivana
I
Nikolic-Hughes
K1 Project, Center for Nuclear Studies, Columbia University, New York, NY 10027; Department of Physics, Columbia University, New York, NY 10027 ewh42@columbia.edu mar@astro.columbia.edu.
Emlyn W
EW
Hughes
Department of Physics, Columbia University, New York, NY 10027 ewh42@columbia.edu mar@astro.columbia.edu.
Malvin A
MA
Ruderman
D001417:Background Radiation; D005720:Gamma Rays; D008849:Micronesia; D009689:Nuclear Warfare
Bikini; Marshall Islands; gamma radiation; nuclear testing; nuclear weapons