luefin tuna contaminated with radiation turned up arooffund the coast of California, just five months after a Japanese nuclear plant had a meltdown. The radiation is believed to be from the Fukushima disaster. Tiny amounts of caesium-137 and caesium-134 were found in 15 fish last year, and the levels found were 10 times higher than those in tuna from several years ago.

Thankfully, the level of cesium is still well below what the U.S. and Japan would deem a health hazard and researchers say the amount detected is not much to worry about.

Researchers say that the amount of cesium detected is not much to worry about.

It's said that the fish were exposed to radiation for one month before making the trip across the Pacific, and they were found to have four becquerels per kilogram of caesium-134, and 6.3 becquerels per kilogram of caesium-137.  Researchers say these are "modestly elevated" levels, and the chemical was released into the ocean after the incident at Fukushima Daiichi in March 2011.

Daniel Madigan at Stanford University led the study, and he said, "I wouldn't tell anyone what's safe to eat or what's not safe to eat. 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."