Low levels of radiation from last year’s Fukushima Diaichii disaster in Japan have been discovered in bluefin tuna swimming of the California coast. Scientists say the trace amounts are not necessarily harmful to people if consumed, and were far less than safety limits the Japanese government has established. But the radiation evident in the tuna caught in August 2011 surprised scientists and revealed just how quickly fish can carry these compounds faster than winds or water currents.
Stanford University researchers, led by Daniel Madigan, found the bluefin tuna were contaminated with very small amounts of cesium-137 and cesium-134. The 15 fish were caught near San Diego last summer and on average had about 10 becquerels (Bq) of the compounds. Madigan and his team believe that the tuna had been exposed to the radiation for a month before swimming east across the Pacific.
Tuna from the Pacific Ocean often carry small levels of radioactive compounds such as potassium-40, which has existed in the globe’s oceans long before humans. The cesium found in the tuna, which on average weighed 15 pounds, only raised the levels of radioactivity in the fish by three percent. The scientists also insist that the levels of cesium will decrease as the fish grow larger and will eventually be excreted over time.
While the scientists will not make a judgement over whether the fish are safe to eat or not, the findings will add to the growing list of long term concerns that the public has over the Fukushima disaster. The fact that these fish could migrate across the Pacific and still carry even the tiniest amount of radiation is just more evidence proving that the long-term damage and worries from Fukushima will stay with us for years.