California Tuna Contaminated With Fukushima Radiation
Bluefin tuna caught off the coast of California are contaminated with radiation from Japan's Fukushima Daiichi nuclear power plant, which melted down after an 8.9 magnitude earthquake and the ensuing tsunami in March. While experts say the risk to humans is low, the findings show that fish can carry radiation faster than water or wind can.
"We were frankly kind of startled," Nicholas Fisher, study coauthor and professor of inter-disciplinary environmental research at Stony Brook University, told the Associated Press. "That's a big ocean. To swim across it and still retain these radionuclides is pretty amazing."
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Bluefin tuna is a prized sushi fish in Japan, where a 2-inch piece sells for almost $13, according to BusinessWeek. They can grow as large as 10 feet and can travel over 45,000 miles in 16 months.
Researchers found evidence of cesium-137 and cesium-134 in Tuna in August, according to the study, published Monday in the Proceedings of the National Academy of Sciences. They found 15 fish with levels of radiation 10 times higher than in tuna caught in previous years, according to the study.
Bluefin are predators, so the radiation accumulation means that their prey likely is contaminated as well, according to the study. Cesium biomagnifies, meaning the concentration increases in the body of the predator as they consume prey contaminated.
The researchers will conduct another survey later this year to determine whether the cesium levels have declined.
"Much will depend on the concentration in the prey fish, which in turn is ultimately dependent on the water concentration," Fisher told Businessweek. "If concentrations in water will eventually decline, as we would expect, due to dilution and dispersion, then concentrations in living organisms will eventually decline as well."
Japan's Chief Cabinet Secretary Osamu Fujimura said Japan will monitor the tuna as well.
"This probably shows the need for international monitoring of marine life," he said, according to Businessweek. "We are studying the best way to collect information on the issue."
But people don't need to worry, Daniel Madigan, study coauthor and researcher at Stanford University, told Reuters.
"I wouldn't tell anyone what's safe to eat or what's not safe to eat," he said. "It's become clear that some people feel that any amount of radioactivity, in their minds, is bad and they'd like to avoid it. But compared to what's there naturally ... and what's established as safety limits, it's not a large amount at all."
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