FishWise Update #3 on Fukushima Nuclear Power Plant-derived Radiation

Created on Tuesday, 06 January 2015


December 2014 Update

As of November 10, 2014, monitoring efforts along the Pacific coast off the US and Canada by Woods Hole Oceanographic Institute scientists detected small amounts of radioactivity from the Fukushima Daiichi nuclear power plant meltdown. The amount of cesium-134 detected was less than 2 Becquerels per cubic meter, which is many times lower than the 7,400 Becquerels per cubic meter maximum level set by US EPA for drinking water. The highest predictions for waters off the California coast are 30 Bq/m3. At such low levels, the radiation is not predicted to harm humans or the environment.

The most rigorous seawater sample testing is being done by a group of citizen scientists led by researchers from Woods Hole Oceanographic Institute. Since the beginning of 2014, the group has collected and analyzed about 50 samples from coastal locations along the west coast, from California to Alaska. To date, none of the samples tested have been found to contain higher than trace levels of cesium.

A new 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 December 1st, the group released results of tissue sampling of sockeye salmon and steelhead trout in northern British Columbia. The average amount of cesium-137 in the samples was 0.27 Bq/kg 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.

In a Los Angeles Times article published on August 20, 2014, Woods Hole Oceanographic Institute 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 does would be 500 times less than a single dental X-ray.”     


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.).

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 is 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. 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)

Import Alert #99-33 instructs FDA field personnel to detain shipments from Japan if the food is likely to contain radionuclide contamination. The FDA’s Import Alert #99-33 website contains a long list of seafood species from the Fukushima prefecture that the Japanese Prime Minister has ordered to be restricted from distribution into the export market, including:

Alaska Pollock, ayu, barfin flounder, black cow-tongue, black rockfish, braddblotched rockfish, brown hakeling, salmon (landlocked), common carp, conger eel, crucian carp, fat greenling, flathead, flathead flounder, fox jacopever, goldeye rockfish, gurnard, halfbeak, black porgy, dace, eel, sandlance, seabass, littlemouth flounder, long shanny, marbled flounder, nibe croaker, northern sea urchin, ocellate spot skate, olive flounder, pacific cod, panther puffer, poacher, red tongue sole, ridged-eye flounder, rockfish (sebastes cheni), sea raven, spotted halibut, slime flounder, spotted halibut, starspotted smooth-hound, starry flounder, stone flounder, surfperch, venus clam, whitespotted char. (FDA 2014)


The U.S. Environmental Protection Agency (EPA) is monitoring levels of radiation in air and precipitation through its RadNet program (EPA 2013). 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).

However, there is a volunteer radiation-monitoring project underway led by scientists from Woods Hole Oceanographic Institute 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. To date, The Our Radioactive Ocean website was updated on June 2, 2014 with this statement:

So far, none of the seawater samples taken from the Pacific Coast have contained any trace of radiation from Fukushima. They have contained the same levels of radiation that were evident in the Pacific Ocean before the Fukushima accident. These levels of cesium-137 measured at all sites are between 1 and 2 Bequerels per cubic meter, and are from the 1960s atmospheric nuclear weapons testing programs. The lack of cesium-134, which only has a two-year half-life for radioactive decay, indicates that none of the Fukushima contaminants have reached the West Coast sampling sites. Therefore, continued support for monitoring is needed as the cesium isotopes are expected to reach the coast in 2014 and levels are predicted to increase over the coming 2-3 years. See more at: (Our Radioactive Ocean 2014)

Kelp Watch 2014 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 2014). 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. The researchers leading the project are confident that the radiation concentration found in kelp samples that will bioaccumulate in the food web that humans are part of will be so low as to pose no harm to human health (Samuel 2014).

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. As of April 30, 2014, no Fukushima-derived cesium has been detected in seawater off the coasts of California, Oregon, or Washington (California Coastal Commission 2014). The leading edge of the radioactive plume appears to have recently reached Vancouver Island off of Canada, and could possibly reach California next year, although coastal upwelling could hold the plume at bay for several years (Rossi et al 2013). 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).

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 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).

Evidence for this can be found to the north of Hawaii and off the coast of British Columbia, where the low levels of cesium detected indicate that the level of exposure along the west coast will be low and marine organisms such as fish are extremely unlikely to accumulate dangerous quantities of radioactivity (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 US 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 US markets (Buesseler 2014).

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 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).

Conclusion and Recommendations

FishWise maintains the same conclusion and set of recommendations from our last update in December 2013. 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. 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. Based on the scientific information available, consuming Pacific seafood is safe. 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 (2014):

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 (2014). Available at: Accessed on June 4, 2014. 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”,