FishWise Update #4 on Fukushima Nuclear Power Plant-derived Radiation

Created on Friday, 26 February 2016



March 2016 Update

As of December 3, 2015, monitoring efforts along the Pacific coast of the U.S. and Canada by Woods Hole Oceanographic Institute scientists and citizen scientists have continued to detect small amounts of radioactivity from the Fukushima Dai-ichi nuclear power plant meltdown. The highest detection level to date came from a sample collected about 1,600 miles west of San Francisco that contained 11 Becquerels per cubic meter of cesium-137 and cesium-134, which indicated that in one cubic meter of seawater (about 264 gallons), 11 radioactive decay events per second were attributed to cesium atoms of both isotopes (Our Radioactive Ocean 2016).

To put this into perspective, in a Los Angeles Times article published on August 20, 2014, Woods Hole Oceanographic Institute (WHOI) scientist Ken Buesseler used the following analogy to describe the human health implications of seawater containing 10 Bq/m3: “If you were to swim in that water 365 days, 6 hours a day, the dose would be 500 times less than a single dental X-ray” (Parsons 2014). So although 11 Bq/m3 is higher than has been seen in the past, it is still more than 500 times lower than the 7,400 Becquerels per cubic meter maximum safety limit set by the Environmental Protection Agency (EPA) for drinking water. At such low levels, the radiation is not predicted to harm humans or the environment (Our Radioactive Ocean 2016).

A collaborative monitoring effort in Canada called the Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) project has included testing local species of fish for Fukushima-derived radiation. On January 29, 2016, the group released results from 26 tissue samples of sockeye salmon and steelhead trout (collected in September and October, 2015) in northern British Columbia. The average amount of cesium-137 in the samples was 1.5 Bq/m3 and the level of cesium-134 was below the detection limit of the analysis, indicating that consuming either species of fish is not a health risk. As a reminder, residual cesium-137 in the oceans is largely the result of nuclear weapons testing in the 1950s and 1960s. The group will publicly report the results of tissue sampling from 80 more fish tested as samples are analyzed.


FishWise is continuing to follow the status of the radioactive plume of seawater from the Fukushima Daiichi Nuclear Power Plant in Japan and its potential to contaminate Pacific seafood. Based on the best scientific information available, consuming Pacific seafood is still safe. U.S. state and federal agencies continue to deliver the message that the levels of Fukushima-derived radiation are unlikely to cause significant harm to the public and the risks are small when compared to other things that threaten public health (e.g. smoking, air pollution, obesity, etc.).

Short background on radiation in the ocean

The vast majority of radioactive particles in the ocean are there as a result of the weathering of rocks and the erosion of continental crust (Buesseler 2014). Until the Fukushima plant meltdown, the primary anthropogenic source of radiation was from fallout from nuclear weapons testing in the 1950’s and 1960’s and from Chernobyl fallout, to a lesser extent. Cesium-137 is the main radionuclide of concern, following the Fukushima disaster, due to its relatively long half-life (over 30 years) and potential to affect human health through bioaccumulation. Cesium-134, which is the “fingerprint” of the Dai-ichi nuclear meltdown, has a short half-life (two years) and therefore decays quickly, making it less of a threat. Both isotopes of cesium are highly soluble in ocean water, meaning that a radioactive plume of these particles quickly dilutes as a result of ocean current and mixing processes (Buesseler 2014).

Who is testing for radiation?

The U.S. Food and Drug Administration (FDA) is the primary federal agency responsible for testing food imported from Japan for radiation. The FDA routinely tests for radionuclide contamination and monitors information and data from foreign governments and international organizations, including the Japanese government’s food sample testing program, the import sample testing programs of nations geographically close to Japan, and the Fukushima-related activities of international organizations like the International Atomic Energy Agency (IAEA) (FDA 2014). In light of the information collected from these sources, in March 2014, the FDA released this update on its website:

To date, FDA has no evidence that radionuclides from the Fukushima incident are present in the U.S. food supply at levels that would pose a public health concern. This is true for both FDA-regulated food products imported from Japan and U.S. domestic food products, including seafood caught off the coast of the United States. Consequently, FDA is not advising consumers to alter their consumption of specific foods imported from Japan or domestically produced foods, including seafood. The FDA continues to closely monitor the situation at and around the Fukushima Dai-ichi facility, as it has since the start of the incident and will coordinate with other Federal and state agencies as necessary, standing ready to take action if needed, to ensure the safety of food in the U.S. marketplace (FDA 2014).

The U.S. Environmental Protection Agency (EPA) is monitoring levels of radiation in air and precipitation through its RadNet program (EPA 2014). Ocean monitoring of Fukushima radiation has received much less attention from U.S. government agencies. Neither the U.S. government nor the state of California has an ongoing testing program for Fukushima-derived radiation off of the California coast (California Coastal Commission 2014). The state of Oregon continues to test drinking water, precipitation and ocean water for radionuclides that could be associated with Fukushima. This data is available at:

There is also a volunteer radiation-monitoring project underway led by scientists from WHOI in Massachusetts. Our Radioactive Ocean is a program in which scientists and citizens can send samples of Pacific Ocean water to be analyzed for Fukushima-derived radiation at Woods Hole. The Our Radioactive Ocean website is updated frequently. Find more information at: (Our Radioactive Ocean 2016).

Kelp Watch 2015 is a project to determine possible radionuclide contamination of kelp forest ecosystems along the California coast by testing kelp samples in multiple locations along the west coast (Kelp Watch 2015). One of the main goals of the project is to soothe public anxiety about the severity of the radiation plume’s impact on coastal ecosystems. Results from the summer 2015 sampling session indicated that there are no detectable levels of cesium-134 in kelp forests along the Pacific coast from Juneau, AK to Humboldt County, CA.

Has the radiation from Fukushima arrived on the West Coast?

Since the disaster occurred in April 2011, a radioactive plume of contaminated seawater has been carried towards the west coast of North America by ocean currents. On November 10th, 2014, scientists announced the presence of small amounts of radioactivity and trace amounts of cesium-134 about 100 miles west of Eureka, CA. According to WHOI’s Buesseler, “The levels are only detectable by sophisticated equipment able to discern minute quantities of radioactivity” (Our Radioactive Ocean 2016). The peak concentration of Fukushima-derived radionuclides is anticipated to reach California between 2016 and 2019 and then gradually decline over the following decades (California Coastal Commission 2014). The highest predictions for the waters off the California coast are 30 Bq/m3.

Should we be worried?

The answer that scientists studying the issue have come to is no. Due to the rapid dilution of the radioactive seawater in the vast Pacific Ocean, the concentration of radionuclides from Fukushima is expected to be only slightly above pre-accident levels, and far below naturally occurring radioactive elements in the ocean (Buesseler 2014). Even the highest estimated levels of radioactivity attributed to Fukushima are more than 400 times lower than levels of naturally-occurring radiation and represent only a tiny increase in total radioactivity above pre-accident levels (California Coastal Commission 2014).

Is Pacific seafood contaminated?

Along the west coast of the United States, low levels of cesium radioisotopes from Fukushima have been found in Pacific bluefin (Madigan et al 2012) and albacore tunas (Neville et al 2014). In 2011, Madigan et al detected very low levels of Fukushima-derived cesium in highly migratory Pacific Bluefin tuna, which the researchers determined had accumulated in the tissue of the fish during the juvenile phase of their life cycles in the western Pacific (Madigan et al 2012). A follow-up study in 2012 found that radiocesium levels in Pacific bluefin had decreased by more than 50%, indicating that the concentration of radioactivity in the ocean from Fukushima is rapidly decreasing (Madigan et al 2013).

Using the same dataset as Madigan et al, Fisher et al concluded that a subsistence fisherman consuming only Pacific Bluefin tuna in amounts five times greater than the average total seafood consumption in the U.S. would receive 0.1% more radiation than the normal annual radiation dose humans receive (Fisher et al 2013).

Some bottom dwelling fish such as flounder tested very close to the reactor off Japan have been found to have levels of radiation above Japanese regulatory limits, so eating those fish is not recommended. However, due to closures of fisheries in the areas near Fukushima and Japan’s strict limits for radiation in seafood, it is extremely unlikely those fish could make it to U.S. markets (Buesseler 2014).

Conclusion and Recommendations

FishWise maintains the same conclusion and set of recommendations from our last update in December 2014. Based on the scientific information available, consuming Pacific seafood is safe. There is no question that there are major concerns regarding the effects of radiation from the damaged Fukushima Daiichi Nuclear Power Plant on human health and the environment in the Fukushima Prefecture. However, the key results from these peer-reviewed studies and from the government tests have been misrepresented in the media and have led to the concern that seafood in the Pacific is contaminated from the Fukushima plant and unsafe to eat. While Japanese subsistence fishers may need to take caution, people in the U.S. eating seafood from the eastern Pacific do not need to spend too much time worrying about their health. We will update our research on this situation as new information becomes available.


Buesseler, K.O. (2014). Fukushima and ocean radioactivity. Oceanography 27(1): 92-105.

California Coastal Commission (2014). Report on the Fukushima Dai-ichi Nuclear Disaster and Radioactivity along the California Coast. 30 April 2014. California Coastal Commission: http://documents.coastal

Fisher, N.S., K. Beaugelin-Seiller, T.G. Hinton, Z. Baumann, D.J. Madigan, J. Garnier-Laplace (2013). Evaluation of radiation doses and associated risk from the Fukushima nuclear accident to marine biota and human consumers of seafood. Proceedings of the National Academy of Sciences USA 110(26): 10670-10675.

Kelp Watch (2015):

Parsons, R (2014). “West Coast waters still safe from radioactivity, but testing continues.” 20 August 2014. Los Angeles Times Food/Daily Dish.

Madigan, D.J., Z. Baumann, N.S. Fisher (2012). Pacific Bluefin tuna transport Fukushima-derived radionuclides from Japan to California. Proceedings of the National Academy of Sciences USA 109(24): 9483-9486.

Madigan, D.J., Z. Baumann, O.E. Snodgrass, H.A. Ergül, H.Dewar, N.S. Fisher (2013). Radiocesium in Pacific Bluefin tuna Thunnus orientalis in 2012 validates new tracer technique. Environmental Science & Technology 47: 2287-2294.

Neville, D.R., A.J. Phillips, R.D. Brodeur, K.A. Higley (2014). Trace levels of Fukushima disaster radionuclides in East Pacific albacore. Environmental Science & Technology 48: 4739-4743.

Our Radioactive Ocean (2016). Available at: Accessed on Feb 8, 2016. See also “Educate Yourself”,

Rossi, V., E. Van Sebille, A.S. Gupta, V. Garçon, M.H. England. (2013). Multi-decadal projections of surface and interior pathways of the Fukushima Cesium-137 radioactive plume. Deep-Sea Research I 80(2013): 37-46.

Samuel, M. (2014). “New Fukushima radiation study will focus on west coast kelp forests.” 15 January 2014. KQED Science.

U.S. Environmental Protection Agency (2014). RadNet Monitoring data. Available at: Accessed on June 4, 2014. See also “Radiation in perspective”,

U.S. Food and Drug Administration (2014). FDA Response to the Fukushima Dai-ichi Nuclear Power Facility Incident. Available at: Accessed on June 4, 2014. See also “Import Alert 99-33”,