18 Jul (NucNet): About 130 deaths and 180 non-fatal cases of cancer may eventually result worldwide from radiation released during the Fukushima-Daiichi accident in Japan, Stanford University researchers said in a study published yesterday.
The university said in a statement that the estimates have “large uncertainty ranges”, but contrast with previous claims that the radioactive release would probably cause no severe health effects.
“Because of inherent uncertainties in the emissions and the health-effects model, the researchers found a range of possible death tolls, from 15 to 1,300, with a best estimate of 130. A wide span of cancer morbidities was also predicted, anywhere from 24 to 2,500, with a best estimate of 180,” Stanford said.
Between zero and 12 of those predicted deaths, and between zero and 30 of the predicted non-fatal cancer cases, were expected to occur in the US, although the methods were less precise for areas that saw only low radionuclide concentrations, the statement said.
Exposure of workers to radioactivity at the Fukushima-Daiichi plant is projected to result in another two to 12 cancers cases.
Those affected according to the model were overwhelmingly in Japan, with extremely small effects noticeable in mainland Asia and North America. The US was predicted to suffer between 0 and 12 deaths and 0 and 30 cancer morbidities, although the methods used were less precise for areas that saw only low radionuclide concentrations.
“These worldwide values are relatively low,” said Ten Hoeve one of the study’s authors. He said they should “serve to manage the fear in other countries that the disaster had an extensive global reach”.
The Japanese government's response to the Fukushima-Daiichi accident was much more rapid and coordinated than that of the Soviets in Chernobyl, which may have mitigated some of the cancer risk, the study says.
Japanese government agencies, for example, evacuated a 20-kilometre radius around the plant, distributed iodine tablets to prevent radioiodine uptake and prohibited cultivation of crops above a radiation threshold – steps that “people have applauded”.
But the study notes that nearly 600 deaths were reported as a result of the evacuation process itself, mostly due to fatigue and exposure among the elderly and chronically ill.
The researchers also modeled “a hypothetical scenario” involving “an identical meltdown” at the two-unit Diablo Canyon nuclear power plant in California, the statement said.
“Despite California's population density being about one-fourth that of Japan's, the researchers found the magnitude of the projected health effects to be about 25 percent larger,” the statement said.
The model showed that rather than being whisked toward the ocean, as with Fukushima-Daiichi, a larger percentage of the Diablo Canyon radioactivity deposited over land, including population centres such as San Diego and Los Angeles.
The study’s authors stressed, however, that none of the calculations expressed “the full scope of a nuclear disaster”.
The study used a 3-D global atmospheric model driven by emission estimates and evaluated against daily worldwide Comprehensive Nuclear-Test-Ban Treaty Organisation measurements and deposition rates.
The study is online: www.stanford.edu/group/efmh/jacobson/TenHoeveEES12.pdf
