Journal: Proceedings of the National Academy of Sciences, 18 April 2013
Authors: Nicholas Fisher, Karine Beaugelin-Seiller, Thomas Hinton, Zofia Baumann, Daniel Madigan, and Jacqueline Garnier-Laplace
What the Study Says: Testing various marine species including Pacific Bluefin Tuna for a Cesium-137 an indicator of the Fukushima contamination and Polonium-210, a naturally occurring radioisotope. Researchers found that contamination levels due to Fukushima radiation were about 100 times lower than even the lowest benchmark protection level set by the EPA. They also determined that low levels of 137Cs occur throughout the Pacific because of contamination from Chernobyl and nuclear weapons testing. Furthermore, researchers found that if these tuna were consumed the additional radiation dose to the average consumer would be negligible. In fact, such a dose is less than that which is routinely obtained by consuming everyday foods, such as bananas.
Key Takeaway: Levels of radiation in Pacific fish are so low that they pose no human health risk.
Journal: Proceedings of the National Academy of Sciences, 25 April 2012
Authors: Daniel Madigan, Zofia Baumann, and Nicholas Fisher
What the Study Says: Researchers tested for the presence of Cesium isotopes in migratory Bluefin and non-migratory Yellowfin tuna samples caught off the California coast before and after the Fukushima incident. They found that neither Bluefin caught before the nuclear incident, nor Yellowfin carried Cesium-134, the primary tracer isotope from the nuclear leak, or any other heightened levels of radioisotopes. The Bluefin, which spawn in Japanese waters, caught post-Fukushima exhibited heightened concentrations of Cesium-134, but scientists believe that those levels had declined over the course of the trans-Pacific migration as the radionuclides decayed and the fish expelled them. Levels found in post-Fukushima were very small and well below food safety thresholds. The research also shows that at the time of the study there were no Fukushima-derived radioisotopes in California waters, and that any that were present were transported there by Bluefin or other migratory fish species.
Key Takeaway: Bluefin tuna transport negligible amounts of radiation as they migrate, but radiation from Fukushima has yet to be found in non-migratory fish.
Journal: Proceedings of the National Academy of Sciences, 24 Feb 2012
Authors: Ken Buesseler, Stephen Jayne, Nicholas Fisher, et al.
What the Study Says: By testing the subsurface waters from the shore of Fukushima to the mid-Pacific, researchers were able to detect Cesium-134 and -137 at concentrations 10-1000 times higher than pre-tsunami levels. Despite these elevated levels, they found that significant ocean dilution had occurred between the leak in March 2011 and the end of their study in June. By this time, Cesium levels 30km (18 miles) offshore had fallen below both Japanese regulatory limits and the levels of other naturally occurring radioactive particles. Researchers did find that these radioactive particles were present in zooplankton as well as mesopelagic fish; indicating that it had entered the Pacific food chain. However, they concluded similarly that the radiation risks due to those radioactive particles were lower than levels generally considered harmful to either marine life or human health.
Key Takeaway: Ocean currents dispersed radioisotopes from Fukushima so quickly that even off the coast of Japan after only a few months, the radiation levels posed no health risk.
Journal: Biogeosciences Discuss, 13 August 2013
Authors: Günter Kanisch & Marc-Oliver Aust
What the Study Says: By sampling fillets of fish caught in the North Atlantic and Baltic seas for radioisotopes Cesium-134 and -137, scientists at the Thünen Institute of Fisheries Ecology in Hamburg were able to determine that radioactivity from Fukushima had been absorbed by marine life, but in very small concentrations. They posit that any radioisotopes from Fukushima present in the Atlantic were carried by air and deposited in the marine environment; tests based on depth seem to support this theory. The majority of Cesium-137 in North Atlantic marine life, however, derives from atmospheric testing of nuclear weapons and the Chernobyl disaster; and even these concentrations are far lower than naturally occurring radioisotopes. The authors conclude that current concentrations of radiation in seafood pose no threat to human consumers judging by the current guidelines for radiation safety.
Key Takeaway: North Atlantic fish carried some traces of radioisotopes from Fukushima, but that radiation poses absolutely no threat to Atlantic seafood as well.
Journal: Environmental Science and Technology, 9 April 2014
Authors: Delvan Neville, A. Jason Phillips, Richard Brodeur, and Kathryn Higley
What the Study Says: Scientists tested twenty-six Pacific albacore samples caught off the coast of the Pacific Northwest coast of the United States between 2008 and 2012. Researchers tested the albacore for Cesium-134, a radioisotope with a short half-life, whose only source in the Pacific is the Fukushima leak. These radioisotopes were found in the majority of samples from 2011 and 2012, but were only present in very small concentrations. Radiation doses from the samples tested were only about 1% of the FDA level of concern for Cesium or .0006% of the annual dose from natural sources to the average American.
Key Takeaway: None of the tested samples would represent a significant increase in annual radiation dose if consumed by humans.