Discuss as:

How radiation will change Japan

Athit Perawongmetha / Getty Images Contributor

A man undergoes a radiation test at a screening center in Kiriyama in Japan's Fukushima Prefecture, Japan.

Radiation experts are painting a sobering picture of the Fukushima nuclear disaster's long-term impact on Japan in a series of reports published today by the journal Nature. At best, the country faces more than a decade of expensive cleanup, including the decommissioning of the reactor complex and the disposal of contaminated debris. At worst, wide areas of land around the complex will have to be abandoned, as they were in Ukraine after Chernobyl.

"On the basis of the Fukushima data so far, it seems likely that in some areas, food restrictions could hold for decades, particularly for wild foodstuffs such as mushrooms, berries and freshwater fish," the University of Portsmouth's Jim Smith, co-editor and lead author of "Chernobyl: Catastrophe and Consequences," wrote in a Nature commentary.

Smith says the levels of radioactive cesium-137, with a radioactive half-life of 30 years, "will determine the long-term impact on the contaminated region and its residents."

NBC's Lee Cowan reports on Japan's radiation standards.

"The extent of cesium-137 contamination at Fukushima is not yet clear, but available data indicate very high levels in some areas," he wrote. Last week, the International Atomic Energy Agency sounded the alarm about high radiation readings in the village of Iitate, 25 miles (40 kilometers) northwest of the Fukushima Dai-ichi complex. The readings ranged as high as 3.7 megabecquerels per square meter. Such readings led the IAEA to suggest an expansion of the current 12-mile-radius (20-kilometer) evacuation zone.

Since then, the reported readings outside the evacuation zone have not been as high. But Smith said that if large areas are contaminated with 0.5 megabecquerels per square meter or more, "evacuation could be for the long term."

One long-term strategy could be to bring in "liquidators" to decontaminate the towns and villages, remove topsoil and resurface roads, "although this approach met with varying success at Chernobyl," Smith wrote.

He said "the long-term response to Fukushima will have to be pragmatic." Radiation exposure limits for the general public might have to be relaxed, for example, going from 1 millisievert per year to 5 to 10 millisieverts per year. Smith noted that millions of people living in areas of high natural radioactivity are exposed to more than 10 millisieverts per year.

"A turning point in my understanding of Chernobyl's impacts came while studying lakes in Belarus during the mid-1990s," Smith wrote. "In an evacuated area, lake fish contained tens of thousands of becquerrels per kilogram. A couple in their early 70s lived near the lake, eating the fish and growing vegetables. They were living off contaminated land, but leading the life they had chosen to lead. This wouldn't by any means be the right choice for everybody, but I am convinced they had made the right decision for them: They were Chernobyl survivors, not victims."

Other reports in Nature's roundup hint at the uncertainties still hanging in the air three and a half weeks after the earthquake and tsunami that led to the Fukushima crisis:

  • David Brenner of Columbia University's Center for Radiological Research explains why experts "really don't know" that much about the long-term health consequences of Fukushima's radiation releases. He said authorities should start assessing "whether it would be reasonable to undertake large-scale population studies among the exposed populations in Japan." Meanwhile, researchers should focus more study on the basic mechanisms by which low doses of radiation cause cancer.
  • The Japan-based Radiation Effects Research Foundation is calling on authorities to start collecting baseline data for a study of Fukushima's effects as soon as possible. Some of the basic measurements are already being collected, but the effort is "scattered and uncoordinated," researchers at the foundation say. In a separate report, Nature says researchers "are finding that making any sense of the data is proving very difficult."
  • Japanese authorities have been monitoring the effects of radioactive iodine-131 on the thyroids of children in the most contaminated areas around Fukushima, and Nature says the first results show minimal thyroid doses in 946 children living in the areas northwest of the plant. The results "seem reassuring that not much iodine-131 has got into children," Richard Wakeford, an epidemiologist at the University of Manchester's Dalton Nuclear Institute, told the journal.

Are you reassured? Feel free to weigh in with your own thoughts about the long-term impact of the Fukushima crisis.

More about Japan's nuclear crisis:

Nature is presenting a live Q&A with the University of Portsmouth's Jim Smith and Nature's Geoff Brumfiel at 11 a.m. ET (4 p.m. London time) on Wednesday.

Join the Cosmic Log community by clicking the "like" button on our Facebook page or by following msnbc.com science editor Alan Boyle as b0yle on Twitter. To learn more about my book on Pluto and the search for planets, check out the website for "The Case for Pluto."