HOW RADIOACTIVE ARE WE?

Worried about Fukushima radiation in seafood? Turns out bananas are more radioactive than fish.

 

Six years ago, a devastating tsunami swept over the eastern edge of Japan, killing over 18,000 people and triggering a nuclear meltdown at the Fukushima Daiichi nuclear power plant. The plant was perched on the coast, so some radiation leaked into the sea. In the months and years following the meltdown, people began to wonder: Did these leaks make Pacific seafood too dangerous eat?  

The answer, then and now, is no, scientists say. The Fukushima leaks were miniscule compared to the vast scale of the Pacific, said Nicholas S. Fisher, an expert on nuclear radiation in marine animals at Stony Brook University in New York. The disaster added just a fraction of a percent to the radiation that’s already in the ocean, 99 percent of which is naturally occurring.

At those levels, you could eat piles of Pacific fish and have nothing to worry about from radiation, Fisher said. The dose of Fukushima-derived radiation from the average tuna fillet, he explained, “would be far less than the total radiation you’d get from eating a banana or flying in an airplane.”

Cesium in the sea

It’s understandable to get the heebie-jeebies from nuclear radiation. “No one can see or touch or feel or smell it,” said Kenneth Buesseler, the director of the Center for Marine and Environmental Radioactivity at Woods Hole Oceanographic Institution in Massachusetts. Most people have a foggy understanding of radioactivity, so real threats get conflated with overblown or made-up ones.

The risks were greatly exaggerated, for example, when several bluefin tuna and one sockeye salmonshowed up in the United States and Canada carrying traces of radioactive cesium from Fukushima. Super-sensitive instruments detected the cesium, but the fish weren’t unsafe to eat. “Just because you can detect it,” Fisher said, “doesn’t mean it’s dangerous.”

Even an iota of radiation sounds unsettling, but fish caught in the United States never came close to breaching government safety limits for food. Japan caps radioactive cesium at 100 becquerels per kilogram. The United States limits it to 1,200. Even at their most radioactive, bluefin tuna caught in California waters clocked in at just a sliver of these limits, at around 10 becquerels of radioactive cesium per kilogram of body weight. A year after the disaster, radioactive cesium levels in California tuna had slipped to an average of just 2.7 becquerels per kilo.

Eating a single dish above the U.S. or Japanese cap is no guarantee you’ll get sick, Buesseler said. “You’d have to eat above that limit every day to have what a government considers a significant cancer risk.”

This isn’t to say all fish everywhere had equally trace levels of radioactivity. Tuna caught in Japanese waters after the disaster had around 15 times more radioactive cesium, Fisher said — so, above Japanese government limits, but below U.S. ones. And certain types of seafood caught in and aroundFukushima Harbor also exceeded Japan’s radiation cap. The good news is that no Fukushima-caught fish have surpassed safety limits since 2015. 

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