Contaminants (Mercury, Fukushima radiation)

Contaminants (Mercury, Fukushima radiation)

Environmental Contaminants in Pacific halibut

The IPHC has been working cooperatively with the Alaska Department of Environmental Conservation (ADEC), to investigate the presence of heavy metals (arsenic, selenium, lead, cadmium, nickel, mercury, and chromium) and persistent organic pollutants (POPs) in Pacific halibut caught in Alaskan waters since 2002. Results from these studies are used to identify ADEC's future research needs.

To date, 2,744 samples have been tested by ADEC. The mean level of total mercury for these samples has been 0.3 ppm, ranging from non-detectable to 2.0 ppm. For comparison, the Food and Drug Administration (FDA) limit of concern is based on methyl mercury (~85% of total mercury) levels of 1.0 ppm, and the Environmental Protection Agency (EPA) and Canadian Food Inspection Agency (CFIA) level of concern is 0.5 ppm. Results from analysis of POPs (i.e. pesticides, selected PCB congeners, polybrominated diphenyl ethers (PBDE’s – found in plastics as fire retardants) dioxins, and furans etc.) found that in general these compounds are either undetectable in Pacific halibut or well below the levels found in other marine fish species. This finding is consistent with the fact that the majority of POP chemicals are fat-soluble, and Pacific halibut have lower fat content compared to other species.

Analysis by the Alaska Department of Health and Social Services (DHSS) has found that most species of fish in Alaskan waters contain mercury levels that are too low to constitute a health risk.

To find out more information on this topic, please follow one of the links listed below:

Specific contaminant level results and guidelines can be found on ADEC's Fish Monitoring Program website:

Fish Consumption Advice (AK Department of Health and Social Services):

State of Alaska Epidemiology Bulletin (July 21, 2014 release):

State of Alaska Risk Management Strategy to Optimize the Public’s Health:

IPHC report on total mercury in Pacific halibut:

Fukushima radiation concerns and Pacific halibut caught in the eastern basin of the North Pacific Ocean

At the IPHC we do not have personnel qualified to speak directly to the risks associated with radiation in seafood; this page is simply intended to provide background information to assist readers on this topic.

Failure of the Fukushima Daiichi nuclear plant following the 11 March 2011 Tohoku 9.1 (Mw) earthquake and tsunami, and resultant leaks of radioactive water and atmospheric exposure have raised questions regarding the safety of seafood caught on the western coast of North America.

In the United States, the Environmental Protection Agency (EPA) and Food and Drug Administration (FDA) and have the responsibility for testing for contaminants in the environment and in food; EPA in a broad sense, and the FDA from a point of sale and food/consumer safety perspective. In Canada, Health Canada monitors environmental exposure, while the Canadian Food Inspection Agency (CFIA) has the responsibility for monitoring seafood safety.

Radiation from Fukushima can arrive in the United States and Canada via water currents, atmospheric deposition, or migratory animals. Tsunami debris is not generally considered a radiation concern [Boice 2012] as the nuclear plant melted down 24 hours after the debris was swept out to sea. Most experts (Boice 2012, Buesseler et al. 2011) feel that a water-based route of Fukushima radiation to the North American coast is of a minimal concern due to the vast amount of dilution that would happen between there and here. That dilution is further assisted by the relatively short half-life (the unit of measurement for a radionuclide to decay) for most of the radioactive nuclides being released: (Iodine-131 [I-131], Cesium-134 [Cs-134]). Essentially those two nuclides would decay within days and never reach the waters on the eastern side of the Pacific Ocean (Fisher et al. 2013). The longer half-life radionuclide is Cesium-137 (Cs-137), and it has been closely monitored by both government bodies and universities. Monitoring of Cs-137 has been done with kelp (Manley and Lowe 2012, Chester et al. 2013), as it is suspected that deposition in rain water was the primary threat during the initial days when there was active dumping of water on the reactors to keep them cool, and radiation was getting into the more global air and moisture circulation from the resultant radioactive steam. Some levels of Cs-137 were found in kelp along the west coast of North America (Chester et al. 2013) in the months following the disaster, which have since decreased after the nuclear plant capped aerial emissions from the plant. Additionally, there is evidence of deer lichen (DOE 2013) in the Aleutians having elevated Cs-137 readings, presumably from atmospheric deposition.

The same report found no increases in radiation levels in five Pacific halibut tested as part of the same study. Recent revelations by the Tokyo Electric Power Company (TEPCO 2013) and widely reported in the press indicate that there is likely ongoing groundwater radioactive contamination occurring at the nuclear plant. This could theoretically introduce increased Cs-137 exposure over time. However, due to the dilution effects, even that is expected to be at extremely low (though not undetectable) levels.

Another concern has been with more highly migratory animals, which is why analyses have been focused on species like tuna (Madigan et al. 2012) and salmon (Fisher et al. 2013). Generally, the primary species caught in the US and Canada do not get close enough to the Japanese coast to get significant exposure (DOE 2013, Madigan et al. 2012). Again, these studies have shown zero to trace levels of exposure. Trace levels are those where a highly sensitive machine is capable of registering exposure, but the levels are 1/1000th to 1/10,000th of the normal radiation (non-Fukushima source) which is naturally found in seawater. There have been reports of sand lance (Buesseler et al. 2012, Fisher et al. 2013) near the Fukushima site having Cs-137 levels at concentrations high enough to be of consumption concern, however those species are not part of the diet of adult migratory tuna or salmon. The southeastern-most documented occurrence of Pacific halibut is in the Sea of Japan off Hokkaido (Mecklenburg et. al., 2002), more than 300 nautical miles to the north and on the opposite side of the Japanese archipelago as Fukushima. As such, eastern Pacific halibut stocks are unlikely to show bioaccumulation from food sources experiencing localized exposure.

The State of Alaska announced the results of radiation testing of seafood from the North Pacific and Alaska by the U.S. Food and Drug Administration in a press release and accompanying data charts in late 2014. The testing confirmed information from federal, state and international agencies that seafood in the North Pacific and Alaska waters poses no radiation-related health concerns to those who consume it.

We have found the following information on non-governmental radiological testing of some north Pacific specimens including halibut:

With their test results from September 2012 here:

And test results from March 2012 with some reading levels for halibut on Cs-134:

Some further sources of information can be found at the following Alaska state, and federal government websites:

Other websites to check:

A DFO-produced article on the arrival of the Fukushima radioactivity plume in North American continental waters:

A report from Health Canada/DFO on radioactivity measurements of fish samples from the west coast of Canada:

Summary Report on Fukushima Accident Contaminants in Canada:

NOAA in collaboration with the FDA and EPA:

EPA RadNet site can be searched for data collected in Alaska regarding any atmospheric deposition or precipitation:

World Health Organization:

There has been some sampling and analysis performed by the Department of Energy out around Adak and Amchitka Islands in collaboration with the University of Alaska. The reports from the study can be found at:

The IPHC does not have plans for radiologic evaluations of fish, as this is largely outside our purview and expertise, but we continue to work with partner agencies on other fish health/pathology related topics. Please visit our Environmental Health and Halibut page.

If you have further questions, concerns, or information to share on this topic, please contact IPHC.


Boice, J. D. Jr. 2012. Radiation epidemiology: a perspective on Fukushima. J. Radiol. Prot. 32(1):N33-40. doi: 10.1088/0952-4746/32/1/N33.

Buesseler, K. O., Aoyama, M., and Fukasawa, M. 2011. Impacts of the Fukushima nuclear power plants on marine radioactivity. Environ Sci Technol 45:9931-9935.

Buesseler, K. O., Jayne, S. R., Fisher, N. S., Rypina, I. R., Baumann, H., Baumann, Z., Breier, C. F., Douglass, E. M., George, J., Macdonald, A. M., Miyamoto, H., Nishikawa, J., Pike, S. M., and Yoshida, S. 2012. Fukushima-derived radionuclides in the ocean and biota off Japan. Proc. Natl. Acad. Sci. U. S. A. 109 (16): 5984-5988.

Chester, A., Starosta, K., Andreoiu, C., Ashley, R., Barton, A., Brodovitch, J.-C., Brown, M., Domingo, T., Janusson, C., Kucera, H., Myrtle, K., Riddell, D., Scheel, K., Salomon, A., and Voss, P. 2013. Monitoring rainwater and seaweed reveals the presence of 133I in southwest and central British Columbia, Canada following the Fukushima nuclear accident in Japan. J. Environ. Radioact. 124: 205-213.

DOE (U.S. Department of Ecology), 2013. Amchitka Island, AK, Biological Monitoring Report, 2011 Sampling Results, LMS/AMC/S08833, Office of Legacy Management, Grand Junction, Colorado, September.

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

Madigan, D. J., Baumann, Z., and Fisher, N. 2012. Pacific Bluefin tuna transport Fukushima-derived radionuclides from Japan to California. Proc. Natl. Acad. Sci. U. S. A. 109 (24): 9483-9486.

Manley, S. L., and Lowe, C. G. 2012. Canopy-Forming Kelps as California's Coastal Dosimenter: 131I from Damaged Japanese Reactor Measured in Macrocystis pyrifera. Enivorn. Sci. Technol. 46(7): 3731-3736.

Mecklenburg, C. W., Mecklenburg, T. A., and Thorsteinson, L. K. 2002. Fishes of Alaska. Bethesda, Maryland, American Fisheries Society. 1037 p.

TEPCO (Tokyo Electric Power Company), 2013. Radioactive material (Total Beta) Density Increase at an Observation hole at Fukushima Daiichi NPS. Available from [accessed November 25, 2013].