Radiation: US tests have left traces higher than Chernobyl

The radiation levels of the US atomic tests during the Cold War in the Marshall Islands in the Pacific Ocean are still too high for human beings to live there.

In their study published in PNAS, scientists from Columbia University discovered that these levels are also much higher than those located around the sites of the Chernobyl and Fukushima nuclear accident.

Throughout the years 1946 to 1958, scientists working for the United States government conducted 67 nuclear bomb tests on the Bikini and Enewetak atolls in the Marshall Islands.

The tests were conducted to learn more about nuclear weapons and their destructive power. Prior to conducting such tests, the US authorities forced the inhabitants of the atoll to forcibly surrender to other sites in the Marshall Islands. During the tests, the researchers found that the effects on two other inhabited atolls (Rongelap and Utirik) were affected. They were also evacuated.

After the tests were completed, US government officials met with representatives from the Marshall Islands to discuss the possibility of cleaning the test sites and the date of return of the displaced. In this new effort, the researchers ventured into the four atolls and badyzed samples of radiation in the soil.

The researchers badyzed soil samples from 11 islands in the four atolls and found that levels of external gamma radiation varied widely from one test to the next. In addition, they indicated that some of the levels were much higher than expected and far exceeded the legal exposure limit set by officials of both countries.

Bikini levels, for example, were measured at 648 millirems per year. The "safe" level established by government agreement is 100 millirems per year. The researchers point out that these levels are also much higher than those around the sites of the Chernobyl and Fukushima nuclear accident.

The same group of researchers also performed two previous tests, one on measuring radiation levels in tree fruits of the affected areas and the other on the crater created by the largest explosion of the region. They reported in documents also published in the PNAS that levels of radiation in fruits too high for human consumption in many islands. They also found that levels of radiation in soil sediments in the crater were still several orders of magnitude higher than normal levels.