The Cesium of Fukushima Found in the California Tunas

2012/05/30 Etxebeste Aduriz, Egoitz - Elhuyar Zientzia Iturria: Elhuyar aldizkaria

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In the tunas captured in the California area a radioactive cesium has been found poured in Fukushima. The researchers stressed that there is no problem in eating these tuna, since the level of radioactivity is well below what is allowed.

In August 2011, a few months after the Fukushima accident, the 15 captured Pacific Atunes (Thunnus orientalis) were examined, which after one or two years of their birth in Japanese waters migrated to the other side of the Pacific. And as recently published in the PNAS journal, high levels of cesium-134 and 137 radioactive isotopes have been detected in all cases.

The Cesio-137 is also found at sea for its trials with atomic explosives, but having a two-year cesium-134 life, it can be directly associated with Fukushima, according to researchers. They see no alternative to explain the appearance of this isotope.

Measured concentrations have been 10 times higher than before the accident. However, they are well below the level of radioactivity admitted in food and only 3% of the naturally acquired radioactivity is due to cessions. For example, the level of 40 naturally taken radioactive potassium isotopes is 30 times higher.

The study of tuna caught this year is the same and the researchers expect to find more cessions in this case, since it is the tuna that have been more time in contaminated Japanese waters.

The researchers wanted to emphasize that these types of biological migrations are a factor to consider in order to know the extent of pollution. In this case, “the radioactive cession has arrived in California, not through the sea currents, but in the muscles of the fish that cross the largest ocean in the world,” said Daniel Madigan of Standford University, who has participated in the research.