Think of the most radioactive landscapes on the planet and the names Chernobyl and Fukushima may come to mind.
Yet research published Monday suggests that parts of the Marshall Islands in the central Pacific, where the United States conducted 67 nuclear tests during the Cold War, should be added to the list.
In a peer-reviewed study, Columbia University researchers report that soil on four isles of the Marshall Islands contains concentrations of nuclear isotopes that greatly exceed those found near the Chernobyl and Fukushima nuclear power plants. On one isle, those levels are reported to be 1,000 times higher.
All four of the islands are currently uninhabited, and three of the four Bikini, Enjebi and Runit are in atolls where nuclear testing took place. But one of the islands, Naen, which measures less than an acre, is in Rongelap Atoll, nearly 100 miles away.
Researchers found concentrations of plutonium-238 on Naen, raising the possibility that the island was used as an unreported dumping ground. Plutonium-238 is a radioisotope associated with nuclear waste and not generally with fallout, said Ivana Nikolic Hughes, a co-author of the research and an associate professor of chemistry at Columbia.
The only other place the team detected this isotope was at Runit, where the United States entombed nuclear waste from bomb testing under a leaking concrete dome.
We cant say for sure that (dumping on Naen) is what happened, said Nikolic Hughes, who directs Columbias K equals 1 Project a multidisciplinary program dedicated to educating the public about nuclear technology. But people should not be living on Rongelap until this is addressed.
The results, published in the Proceedings of the National Academy of Sciences, have reignited debate on the U.S. government monitoring residents health in the Marshall Islands and its assurances that locals face little risk from radioactivity.
Some researchers have declared Rongelap safe for re-habitation. But the Columbia study suggests that, for now, people not return to Rongelap or Bikini atolls, where Naen and Bikini are located, until certain areas have been more thoroughly cleaned. More than 600 people have already returned to parts of Enewetak atoll where Runit and Enjebi are located.
We are concerned about what is being consumed on Naen and at what level, said James Matayoshi, the mayor of Rongelap Atoll. He said he didnt like the idea of people collecting food from Naen and the islands near it, because he doesnt know what kind of risk that poses for his constituents health.
Others are not so sure the studys results are valid.
Terry Hamilton, the U.S. Department of Energys lead researcher on Marshall Island radiation issues, said although the Columbia teams approach seemed reasonable given the costs of pursuing such research in a remote part of the world, he was concerned their methodology and equipment could have overestimated the radiation they were detecting.
Nikolic Hughes and her husband, Emlyn Hughes, a Columbia University particle physicist and co-director of the K equals 1 project, rejected claims their methodology was flawed. The intent of their studies, they said, was to provide the Marshallese with an independent assessment research not considered suspect because it was conducted by a government responsible for the contamination.
The work provides valuable background information for local policymakers, said Jan Beyea, a retired radiation physicist who has worked with the National Academy of Sciences but was not involved with the research. He added the results could tip the question of resettlement either way.
Implicitly, I think these results might caution efforts to return, because of the readings found, Beyea said. On the other hand, she noted, information that only certain uninhabited islands have levels that exceed agreed-upon safety standards could mean the return to some places might be made easier.
