Between 1965 and 1971, amid the rising global tensions of the Cold War, the U.S. government conducted three underground nuclear weapons tests deep beneath the island of Amchitka near the eastern end of the Aleutian Islands chain.
Buried deep in the strata is the radioactive legacy of those tests. Concern that poisonous radionuclides could be reaching surface waters led to an independent study of the area's marine environment in 2004 conducted by scientists from six universities, accompanied by Aleut scientists familiar with subsistence practices of local residents.
The results of the Consortium for Risk Evaluation with Stakeholder Participation (CRESP) study were released in August and showed that none of the marine organisms tested had radiation levels that would pose a threat to humans.
On Monday, scientists who gathered geophysical and biological samples during three expeditions to Amchitka in the summer of 2004 were in Homer to discuss their findings at a forum arranged by the Alaska Maritime National Wildlife Refuge.
"A large number of samples were analyzed and were below the minimum detectable activity level. All the samples were far below the food safety levels, so there is no indication at the moment of any problem, and there is a very diverse and thriving marine ecosystem around Amchitka that deserves protection," said Joanna Burger, a professor of biology at Rutgers University in New Jersey.
Burger said once the project was under way, discussions with members of the Aleut communities and with U.S. Fish and Wildlife scientists and others, it was clear three issues were of prime importance around Amchitka.
"One is the subsistence foods for people who live out there," Burger said. "The second was commercial fisheries. Dutch Harbor is the world's leading port for fish and seafood in the world. The third was the marine ecosystem."
The CRESP study determined that levels of radionuclides measured in biota were within the range found in biota from other marine environments in the Northern Hemisphere and "below any levels known to impact organisms or ecosystems."
The CRESP expedition tested samples of seabirds, marine algae, invertebrates and fish, according to a summary of the study. In all, some 4,500 pounds of samples were analyzed. Organisms were collected from several levels of the food chain and from near all three test shots.
The nearby island of Kiska provided samples for reference purposes. Appropriate species and tissues were analyzed looking for a wide range of radionuclides that would be of concern to human and ecological health, the summary said.
According to the study, the exact composition of radionuclides that would be expected to remain encased in the test cavities is classified. CRESP used other sources to select which radionuclides to analyze. They included Cesium-137, which collects in edible tissues, Strontium-90, which accumulates in bone, as well as isotopes of plutonium, uranium and other elements. The study is considered complete enough to provide a baseline for long-term monitoring, according to the summary.
Among the study's determinations were that there was no indication of substantial localized discharge of freshwater through the ocean floor an expected pathway for migration of radionuclides from the test cavities. In other words, no path of escape was found.
For most radionuclides, there was no detectable difference between Amchitka and Kiska, the reference site, and for the two that showed a difference, the levels were well below those that would cause health concerns.
"The nature and spatial pattern of detectable radionuclides do not suggest that they are attributable to the Amchitka test shots," the study said.
The study also provided scientists with a list of life forms in which radionuclides would be expected to accumulate first should a leak occur. These "bio-indicators" could be used in a future monitoring program.
The radioactive elements present in the test cavities have varying half-lives. Some will remain highly toxic to surface life forms for tens of thousands of years. Also troubling is there is no way to predict where leakage might occur.
"If anything ever comes out from the test shots into the marine environment, where is it going to come out?" Burger said. "We can't tell when the leakage would occur or where the leakage would occur."
What is known is there is no leakage now, she said, but the unknowns demand future environmental monitoring.
Researchers from Rutgers University, Vanderbilt University, UMDNJ Robert Wood Johnson Medical School, the University of Alaska Fairbanks, the University of Pittsburgh and the University of Alberta participated in various aspects of the CRESP study.
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