Radiation from fish and lobsters near the U.K.’s biggest nuclear polluter suggest radioactive material dumped into the sea from Japan’s Fukushima Dai-Ichi power plant isn’t a long-term health threat, scientists said.
The Sellafield nuclear-waste plant in northwest England has discharged about 44 times more cesium-137, one of the most harmful radioactive materials to humans, into the Irish Sea since 1952 than what has leaked from the Japanese plant this month, based on data from both sites. Still, average radiation doses by seafood-consumers near Sellafield over 15 years have been half the recommended limit, studies show.
The Sellafield research suggests bans on Japanese seafood are unnecessary, said Richard Wakeford, a professor of epidemiology at the University of Manchester’s Dalton Nuclear Institute. The U.S. and European Union are among nations that have curbed imports from Japan, and hotels including Shangri-La Asia Ltd.’s luxury chain have stopped serving seafood from the East Asian country because of radiation fears.
“It is not a long-term problem, and that’s what you learn from Sellafield,” Wakeford said in a telephone interview. “I don’t think there’s any need for this knee-jerk reaction, which is hitting someone when they’re down.”
About 4,700 terabecquerel of radiation leaked from the plant into the sea between April 1 and April 6, Junichi Matsumoto, a general manager at Tokyo Electric Power Co., the plant operator, said at a news conference today. That’s 31,333 times more than what the utility said it dumped into the sea from April 5. The leak included 940 terabecquerel of cesium-137, which takes 30 years to decay by half and can cause cancer if ingested.
Between 1952 and 2009, Sellafield legally discharged about 41,353 terabecquerel of cesium-137, based on data from the U.K. Environment Agency and the Journal of Radiological Protection. The biggest discharge in a single year was 5,200 terabecquerel in 1975.
The highest radiation doses in the U.K. were found in the 1970s among consumers of fish and shellfish in Cumbria, the English county in which Sellafield is located.
The average dose in that group was as much as 3 millisieverts a year, according to a study published in 2000, triple the annual limit of 1 millisievert for man-made exposures set by the Ottawa-based International Commission on Radiological Protection. The group’s average dose between 1995 and 2009 was 0.5 millisievert, Environment Agency data show.
“Although it was fairly high levels being discharged, that initial discharge has stopped,” said Tony Irwin, a visiting nuclear technology lecturer at the Australian National University and University of Sydney, who helped review practices at Russian reactors after the world’s worst nuclear disaster at Chernobyl, Ukraine, in 1986. “You get a vast dilution with the sea. It was more of a short-term effect.”
Globally, people are exposed to an average of 2.4 millisieverts a year from the earth’s crust and cosmic rays, according to the World Nuclear Association in London. Exposure of 100 millisieverts a year is the lowest level at which any increase in cancer is evident.
A becquerel is a measure of radioactivity and a terabecquerel is one trillion becquerel. A millisievert is a measure of the dose of radiation received by a person. The formula for converting becquerel into millisievert varies according to the radioactive material involved.
An excess of leukemia cases was observed between 1950 and 1980 among children in Seascale, the nearest town to the Sellafield plant. A 1990 study suggested the increase was linked to men employed at Sellafield who were exposed to radiation of 100 millisieverts or more before conceiving children. Subsequent research disputed those findings, and suggested the cases may have been related to an unidentified infection.
“On current knowledge, environmental radiation exposure from authorized or unplanned releases could not account for the excess” leukemia cases, an independent committee wrote in a 1996 report.
Japan plans to measure the radiation exposure of 150,000 residents near the Fukushima plant, the Yomiuri newspaper reported yesterday, citing Welfare Minister Ritsuo Hosokawa.
Areva SA will deliver a decontamination unit to the Fukushima plant to help Tepco remove radioactive water, the Paris-based company said April 19. Tepco wants to start using the unit by June, said Junichi Matsumoto, a company official.
U.S., European Curbs
Russia restricted supplies of fish and marine products from 242 processors in Japan, joining the U.S. and EU in limiting shipments. India said April 5 it suspended Japanese food imports for three months or until “credible information” on the radiation hazard is available.
Japan exported 565,295 metric tons of marine products worth 195 billion yen ($2.4 billion) last year. The northern island of Hokkaido and southern prefectures of Kagoshima and Nagasaki are the nation’s major exporters of seafood, said Rika Tatsuki, a spokeswoman for the National Federation of Fisheries Co-Operative Associations in Tokyo.
Contamination of the earth within 100 kilometers of the crippled Fukushima plant is likely to have a greater long-term effect on human health than radiation in seawaters, said Peter Burns, a former chairman of the United Nations Scientific Committee on the Effects of Atomic Radiation.
“The only significant pathway at this stage is the contamination that’s on the ground, and people getting external radiation from living in the contaminated area,” Burns, now retired, said by telephone from his home in Melbourne.
Sellafield, built to produce explosives during the Second World War, became the world’s first commercial nuclear power station, and is now a nuclear waste-reprocessing plant, according to its website. The facility is owned by the U.K. government’s Nuclear Decommissioning Authority and is operated by Sellafield Ltd., a joint venture of Areva, San Francisco-based URS Corp. and London-based AMEC Plc.