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Tuesday, Oct. 4, 2011

U.K. expert says limits on radiation 'unreasonable'


Staff writer

The government should relax restrictions on the amount of allowable radiation in food and also rethink its evacuation criteria for Fukushima Prefecture, site of the world's worst nuclear accident since Chernobyl, a British physics professor said Monday.

"The real problem is fear," Oxford University professor emeritus Wade Allison said at the Foreign Correspondents' Club of Japan in Chiyoda Ward, Tokyo.

Citing the doses of radiation received in medical procedures, such as CT and PET scans, Allison said Japan's standard — which bans the sale of food containing more than 500 becquerels per kilogram of radiation and requires the evacuation of areas receiving 20 millisieverts a year — is far too conservative.

While setting standards is difficult for the government, which must balance radiation risks against the hardships of evacuation, Allison argues its conservatism does more harm than good.

The 500-becquerel limit on food sales imposed by the Japanese government is identical to the EU's limit but lower than the 1,200-becquerel limit set by the United States, which, Allison asserts, is also overly cautious.

PET scans, which emit gamma rays to map internal organs, usually the brain, give patients a dose of 15 millisieverts of radiation in a couple of hours, which is the equivalent of eating 2,000 kg of meat tainted with 500 becquerels per kilogram of cesium, he said.

Therefore, the government regulation is "unreasonable," he said. He also cited an article in Swedish newspaper Dagens Nyheter from April 24, 2002, that states, "the Swedish Radiation Protection Authority admits: 'We condemned tons of meat unnecessarily.' "

As for the evacuation criteria used in Fukushima, the government adheres to the standard set by the International Commission on Radiological Protection, which advocates a yearly limit of 20 millisieverts of radiation exposure.

Allison said that cancer patients receiving radiotherapy can tolerate in excess of 20,000 millisieverts per month, far beyond the "unreasonable" evacuation criterion of 20 millisieverts, he said, adding that 100 millisieverts a month would be appropriate.

"Evacuation is at least as traumatic as radiotherapy treatment," he said. "The criterion has taken no account of damage to personal and socioeconomic health."

Seiichi Nakamura, a researcher at the Health Research Foundation, in Kyoto, said he agrees that Japan can raise the limits, but stresses his position is not as extreme as Allison's.

"My feeling is that 20 millisieverts a year is already quite high, but it may be OK to raise it a bit more," said Nakamura, who helped research cancer risk in people in Kerala, India, an area of unusually high naturally occurring radiation. "The food standard can be raised closer to the more internationally recognized level of 1,000 becquerels per kilogram."

Allison insists that he has no ties to the nuclear industry.



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