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Radioactivity in fish and shellfish samples from the west coast of Canada after Fukushima (2011-18)

June 13, 2022 fukushimainform Leave a comment

The purpose of this post is to bring the public up to date on monitoring efforts of a research program into the impact of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on environmental and public health here in North America. This post is part of an ongoing series summarizing work carried out by the Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) project which operated from 2014-2020. Radioactive contamination of the Pacific Ocean following the FDNPP accident raised public concern about seafood safety, particularly in coastal Indigenous communities in British Columbia where I live. To address this, InFORM along with Health Canada, Department of Fisheries and Oceans Canada and First Nations partners have collected and analyzed a total of 621 samples of commonly consumed salmon, ground fish, and shellfish from the Canadian west coast from 2011 to 2018. We examined the activities of cesium radioisotopes (134Cs half-life ~2 years and 137Cs half-life ~30 years) that were released in relatively large quantities from the Fukushima Dai-ichi Nuclear Power Plant (FDNNP) disaster in 2011 and would be most likely to pose radiological health concerns for human consumers of marine animals. Through careful analysis to determine the amount of radioactive isotopes in the seafood we have been able to carry out a health impact assessment. I wish to thank the following First Nations from British Columbia, Canada, for their generous donation of fish: Tr’ondëk Hwëch’in, Selkirk, Champagne and Aishihik, Taku River Tlingit, Tahltan, Nisga’a, Wet’suwet’en, Wuikinuxv, ‘Namgis, Hupacasath, Syilix, and Vuntut Gwich’in. I also thank Kayla Mohns and Brenna Collicutt of the Hakai Institute for assistance with the collection of shellfish samples. These results have recently been published in the peer-reviewed scientific literature in the Journal of Environmental Radioactivity and can be accessed here.

Highlights of the paper and key findings:

the vast majority of fish and shellfish did not have detectable levels of ¹³⁷Cs or ¹³⁴Cs where the minimum detectable level was 0.7 — 1.0 Bq kg^-1 fresh weight for 6 hours of analysis by counting with a sensitive gamma emission spectrometer
19 fish that had detectable levels of ¹³⁷Cs were freeze dried and recounted for 336 hours and found to have an average ¹³⁷Cs content of 0.29±0.02 Bq kg^-1 fw
2 of these 19 fish had detectable levels of ¹³⁴Cs, the short-lived isotope, which showed clearly that fallout from the FDNPP was present in these particular fish. Given that the ratio of ¹³⁷Cs:¹³⁴Cs in the releases from the FDNPP was 1:1 we determined that the contribution of contamination in these fish from the nuclear accident was 49% and 24% respectively with the majority of caesium contamination coming from other sources like nuclear weapons testing and the Chernobyl disaster in the 20^thcentury
38 shellfish showed no contamination from FDNPP in either their shells or meat
8 years of measurements showed that radioactivity in fish was dominated by naturally occurring radioisotopes and that levels of human-made radioisotopes remained small in the Pacific off North American following the FDNPP disaster
upper bounds for ingested doses of ionizing radiation from ¹³⁷Cs was determined to be ~0.26 micro-Sieverts per year and far below the annual effective dose of 2400 micro-Sieverts from exposure to other sources of radiation
we conclude that fish and shellfish from the Canadian west coast are not a radiological health concern despite the FDNPP accident of 2011

What we did

Samples were collected with the help of 13 First Nations, the Department of Fisheries and Oceans and the Hakai Institute in coastal waters and rivers of western Canada at sites indicated on the map below.

1-s2.0-S0265931X22001254-gr1_lrg.jpg — Figure 1 (a) Map of fish samples collected from 2014 to 2018 through the InFORM project. (b) Map of shellfish (bivalves) collected in 2016 and 2017.

For fish we removed the skin and bone to measure fillets which are typically consumed. Whole-body tissues of mussels, oysters, and clams were processed as they are generally eaten whole, but for scallops only the muscle itself was processed. In addition, we crushed up the shells of the individual shellfish to determine if radiocesium had accumulated in the shell as they are sometimes used to fertilize garden beds or adjust the hardness of rainwater used for home gardens. We measured the radiocesium and naturally occurring radioisotopes in the samples using gamma spectrometry which you can learn about here. All samples were analyzed for 6 hours to screen samples for the presence of ¹³⁷Cs and a subset of 19 were counted for a further 336 hours to determine if any ¹³⁴Cs was present. This represents 10110 hours (more than 421 days) of counting time.

What we found

Results of the 6 hour counts and the extended counting samples can be found in here and here respectively. Given the extremely low levels of ¹³⁷Cs present in the fish tissue (almost always below our minimum detectable concentration for individual fish) we averaged the gamma emission spectra of all fish collected in each year to determine the average ¹³⁷Cs content. ¹³⁷Cs content of all fish samples in each year fell between 0.18 and 0.25 Bq kg^-1 fresh weight with the highest average concentration in 2017 and the lowest 2015. Data are here. The challenge of measuring and quantifying the amount of ¹³⁷Cs can be understood by looking at the gamma emission spectrum and the averages for each year between 2014 and 2018 in the following figure.

1-s2.0-S0265931X22001254-gr2_lrg.jpg — Figure 2 Spectral summation of fish samples from 2014 to 2018, normalized to sample number. (a) Overlay, 150–2000 keV (b) Overlay with focus on the principal emission line for ¹³⁷Cs at 661.7 keV

What the figure shows is that even after averaging the results for every fish collected in each year it was difficult for our team to detect human-made caesium isotopes. There was also no clear trend in time with ¹³⁷Cs neither increasing nor decreasing with time in Pacific fish. In fact, the level of ¹³⁷Cs found in the Pacific salmon was similar to levels found in Atlantic salmon (Table 4, 0.20 Bq kg^-1) we collected in 2017 and analyzed from the Miramichi River on Canada’s east coast in New Brunswick. Careful analysis of 19 fish with longer counting times led us to be able to detect 2 fish with measurable levels of ¹³⁴Cs which was an unmistakable sign of contamination from the FDNPP. However, given our understanding of the releases of ¹³⁷Cs and ¹³⁴Cs from the FDNPP following the disaster, most of the ¹³⁷Cs present in the fish reflected contamination in the Pacific from nuclear weapons testing and the Chernobyl disaster rather than events following the 2011 meltdowns at FDNPP. For shellfish harvested from Canada’s west coast in 2016 and 2017, spectral summation of fresh weight samples (tissue and shell, respectively) yielded no detectable radiocesium or any other anthropogenic isotopes.

What it means

From 2011 to 2018, radioactivity measurements were made by the Fukushima InFORM project of 621 fish and shellfish samples harvested from Canada’s west coast. To investigate the impact of the oceanic contamination plume of Fukushima radioactivity to coastal waters, we used highly sensitive analyses and data reduction techniques to show that the concentration of ¹³⁷Cs in the tissue of marine fish has not changed (0.18–0.25 Bq·kg⁻¹ fw) from 2014 to 2018 while that of shellfish was undetectable. Relative to the abundance of naturally occurring isotopes like 210-Polonium in the same fish samples or to the annual dose exposure due to naturally occurring background radiation, it is abundantly clear that, by any metric, the radiocesium content of fish and shellfish from Canada’s west coast does not constitute a health risk, despite the FDNPP accident of 2011. The ecosystem and public health on the west coast of North America was never under threat from the FDNPP accident.

Biota, British Columbia, Cesium, Citizen Science, Coastal, Isotope, Marine Life, Monitoring, N Pacific, NE Pacific, North America, Oceanic, Sample type, Seawater, Uncategorized

Insignificant Environmental and Public Health Risk from Fukushima in North America 8 Years On

March 11, 2019 fukushimainform Leave a comment

By Jay T. Cullen

Summary infographic for the Fukushima InFORM project including our measurements in North America, Japanese measurements, historical data and safety guidelines.

I am writing this post is to bring the public up to date on monitoring efforts of my research program into the impact of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on environmental and public health here in North America. This post is part of an ongoing series summarizing work carried out by the Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) project. Eight years since the peak in releases to the environment our project continues to measure radioisotopes released from the FDNPP that have the potential to present radiological health risks to living things. InFORM makes measurements of levels in seawater and common marine organisms as consumption of seafood is one of the most likely ways that residents of North America could be exposed to Fukushima derived contamination. We have found that:

Maximum contamination levels in seawater from Fukushima measured in waters offshore (~1500 km) and onshore British Columbia are now known to be about 8 to 10-fold lower than levels present in the North Pacific during the height of atmospheric nuclear weapons testing in the 1950’s and 1960’s. These levels are roughly 1000-fold below the maximum allowable drinking water standards for these isotopes.
Levels in Pacific salmon returning to North America have not changed in a statistically significant way since before the disaster and are lower than peak levels measured in the 1960’s.
As was reported in 2015 in this comprehensive study by Health Canada and backed up by measurements made by the international scientific community the release of radioisotopes from Fukushima will have no measurable impact on the health of the marine ecosystem in the northeast Pacific nor on public health in North America.

Eight years after this disaster it is important to remember those lost in the tsunami and those still displaced from their homes and communities struggling to recover.

Offshore and Onshore Citizen Science Monitoring of Seawater Contamination

The levels of radionuclide contamination in seawater is important to understand as the levels that ultimately are found in marine organisms is set by seawater levels. InFORM recently published a peer-reviewed paper in Environmental Science and Technology summarizing our results to date. Offshore levels of Fukushima derived isotopes have peaked and are now decreasing at our westernmost stations 1000-1500 kilometers from the North American coast. The peak levels are well below levels measured in the same waters during the 1950’s and 1960’s when atmospheric nuclear weapons tests were common. Our study area is shown in the figure below along with the prevailing currents that brought the contaminated seawater to North America.

Study area showing the onshore-offshore sampling line occupied by the InFORM project with the support of Department of Fisheries and Oceans Canada. Station P26 is ~1500 kilometers from the coast of North America.

Every month since about December 2014 volunteer citizen scientists in 15 coastal communities up and down the shores of British Columbia have collected seawater samples at the beach and returned them to our laboratories for analysis. The sampling network is shown below.

Coastal seawater monitoring stations in British Columbia.

Since monitoring began coastal seawater concentrations have increased as the Fukushima contamination plume arrives. For the first time we can report that contamination levels have ceased increasing near the coast and are beginning to diminish. The activity of ¹³⁷Cs leveled off at ~4 Bq per cubic meter of seawater which is about 2-4 times the background from weapons testing that existed here before Fukushima. Both the open ocean and coastal monitoring data are summarized in the figures below.

Monthly averaged ¹³⁷Cs detected in seawater in Bq per cubic meter collected along the coast of BC from 2014-2018.

Levels of ¹³⁷Cs in seawater (Bq per cubic meter) measured in samples collected by our citizen scientists along the BC coast compared to maximum levels measured offshore, weapons testing fallout maximum activities in the eastern Pacific in early 1960’s and Canada’s action level for the isotope in drinking water.

Offshore levels of ¹³⁷Cs peaked at a little less than 10 Bq per cubic meter and have been diminishing as less contaminated water moves across the Pacific from the west. Coastal activities have peaked at lower levels likely because freshwater runoff from the continent is less contaminated than the seawater and dilutes the Fukushima contamination.

Monitoring of Pacific Salmon

Since 2014 we have collected and analyzed ~100 Pacific salmon and steel head trout per year returning to rivers up and down the BC coast from the Pacific Ocean. There has been no statistically significant increase in the levels of human-made isotopes in the fish since before the Fukushima disaster. Below we plot the maximum levels we have detected in fish returning to BC from 2011-2017 compared to levels measured in Pacific salmon during the 1960’s when weapons fallout levels were highest surface waters.

Radiation%20in%20NE%20Pacific%20Salmon%20through%20time_max-01.png — Maximum levels of ¹³⁷Cs detected in BC salmon post Fukushima compared to levels in Pacific salmon in the mid-1960’s owing to weapons testing fallout.

On average our Pacific salmon have ~0.2 Bq per kilogram wet weight and it is important to note that there is no statistically significant different in the average contamination level in the fish in years 2011-2017. We are only showing the maximum value detected in each year and have not shown how much variability exists in the yearly data for clarity. Levels of contamination in the 1960’s were >10-fold higher than our average levels in years post-Fukushima. The dose of ionizing radiation experienced by consumers of Pacific fish and shellfish is still dominated by the presence of naturally occurring radioisotopes in the Uranium and Thorium decay series (principally 210-Polonium) and remains well below levels that might represent a health risk.

We will continue our monitoring efforts likely through the end of this calendar year and continue to report our results as they are generated. As always I am happy to answer any questions related to the project and our findings.

Cesium, Isotope, Location, NW Pacific, Peer Reviewed, Sample type, Seawater

Update: Fukushima Derived Contamination in Pacific Surface Water Up Until 2017

October 28, 2018 fukushimainform Leave a comment

Northeast subarctic Pacific from the deck of the Canadian Coast Guard Ship J.P. Tully in September 2

By Jay T. Cullen

The purpose of this post is to summarize a recently published, peer-reviewed study that documents levels of Fukushima derived contamination in surface waters of the Pacific Ocean. This post is part of an ongoing series aimed at communicating scientifically derived information about the impact of the disaster on marine environmental and public health. Michio Aoyama and colleagues measured the activity of Cesium-137 (¹³⁷Cs, half life ~30 years) and Cesium-134 (¹³⁴Cs, half life ~ 2 years) in seawater collected from the western Pacific Ocean including waters off the coast of Fukushima Prefecture from 2011-2017. They found the following:

Contamination decreased dramatically and rapidly in waters offshore of the Fukushima Daiichi Nuclear Power Plant (FDNPP) from maximum values of ~3000 Becquerel per cubic meter (Bq m^-3) of seawater in 2011 to values in 2015-16 of ~2-3 Bq m^-3. This precipitous decline is consistent with the ongoing but relatively low rates of release of radionuclides from the site compared to the bulk of contamination that was released in March-April 2011.

Levels of ¹³⁷Cs close to FDNPP now are similar to levels of contamination present there before the disaster occurred (1.5-2 Bq m^-3) owing to atmospheric nuclear weapons testing in the middle of the 20^th century.

Levels in the western Pacific were around 1-7 Bq m^-3 in 2011-2012 but stabilized at lower values in 2017.

**Levels being measured in nearshore and offshore waters in the western Pacific near to Japan do not approach levels known to represent a credible risk for ocean or public health**. These results in the western Pacific are consistent with what the Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) project is finding in the eastern Pacific off of North America.

Aoyama and others recently published their study in the Journal of Environmental Radioactivity. The collected and analyzed surface seawater for the presence of radiocesium isotopes between 2011 and 2017 in waters of the western Pacific in the following locations:

Boundaries of areas (boxes) sampled by Aoyama et al. (2018) in the western and central Pacific Ocean.

The activity of ¹³⁷Cs and ¹³⁴Cs in Bq m^-3 with time that they found are summarized in the following figure:

Long term trends (2011-2017) in radiocesium activity in boxes defined in the first figure. Solid blue squares are ¹³⁷Cs activity concentration and open red circles represent ¹³⁴Cs.

The researchers found that in Box 2 (closest to the FDNPP) contamination in surface waters offshore were highest in early 2011 coincident with the largest releases from the site in March-April of that year when the vast majority of radionuclides were released to the atmosphere and directly to the ocean. Values dropped dramatically so that by 2014-2016 levels were ~3 Bq m^-3 and similar to levels of contamination measured before the disaster occurred owing to nuclear weapons testing that occurred in the 1950s-60s. Note that the concentrations of ¹³⁴Cs diminish relative to ¹³⁷Cs, and the red symbols on the figure diverge from the blue symbols, because ¹³⁴Cs has an ~2 year half life and is decaying away from the environment much more rapidly. Indeed, it is becoming increasingly challenging analytically to detect Fukushima ¹³⁴Cs in environmental samples. Contamination farther offshore in Boxes 4-6 indicate that maximum levels of contamination from Fukushima approached by did not exceed 200 Bq m^-3 in 2011 and are now ~2-3 Bq m^-3.

Based on best estimates of how much radiocesium was released from FDNPP in March-April 2011 the authors used a model of the water circulation and mixing in the Pacific to predict the levels and movement of Fukushima ¹³⁴Cs in the Pacific from April 2012 until October 2016. The results of the modeling study are summarized in the following figure:

Horizontal distribution of ¹³⁴Cs from Fukushima for the period April 2012 to October 2016. Open circles represent observations/measurements of ¹³⁴Cs while shading reflects model results.

What the model and observations indicate is that the bulk of contamination from the site went into the Pacific Ocean in 2011 and that rates of release from the site after that time are very small in comparison. Most of the Fukushima contamination is now in the eastern Pacific near to North America and that levels in behind the main body of contamination are difficult to detect. Similarly, the lack of appreciable ¹³⁴Cs and ¹³⁴Cs/¹³⁷Cs activity ratios close to FDNPP indicate that there is little evidence for ongoing fission in the reactors at the site as is commonly speculated by those with little scientific training. The levels the scientific community is measuring close to FDNPP and those expected and measured in waters close to North America do not represent a significant risk to the marine ecosystem or public health.

The Fukushima InFORM project will continue its monitoring activities in the eastern Pacific until Spring 2019.

Continue reading Update: Fukushima Derived Contamination in Pacific Surface Water Up Until 2017 →

British Columbia, Cesium, Marine Life, Peer Reviewed, Potassium, Sediment

Monitoring Fukushima Contamination in Pacific Salmon and Soil in British Columbia

March 11, 2018 fukushimainform Leave a comment

Beautiful sockeye salmon photographed by Eiko Jones.

Seven years on, since the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, it is useful to start to bring together information from scientific studies of the impact of the contamination on the North American environment and its people. I recently wrote to communicate the most recent results of the Integrated Fukushima Ocean Radionuclide (InFORM) project. This post summarizes a recently published, peer-reviewed paper by colleagues lead by Dr. Krzyzstof Starosta of Simon Fraser University in BC working in parallel to InFORM. The open access paper was published in the Canadian Journal of Chemistry and was recently recognized with the “Best Paper Award” by the journal. They studied the concentrations of anthropogenic radioisotopes (¹³⁴Cs half-life ~2 years, ¹³⁷Cs half-life ~30 years) and naturally occurring radioisotope ⁴⁰K (half-life 1.25 billion years) in Pacific salmon (sockeye, chum and chinook) and in soil and roof debris collected in southern British Columbia to determine the local impact of the FDNPP accident. Their results were as follows:

¹³⁴Cs (a fingerprint of Fukushima contamination) was not detected in any of the salmon samples
¹³⁷Cs was not detected in sockeye or chum salmon but was detected in all chinook with an average level of ~0.2 Bq kg^-1
Annual dose from artificial radionuclides to a human consumer of chinook salmon was estimated to be ~1/300 of the dose owing to naturally occurring isotopes in the fish and ~1/30,000 of the annual dose experienced for all other natural sources by the average Canadian
Most soil samples contained ¹³⁴Cs and ¹³⁷Cs which was delivered to the region by atmospheric transport shortly after the disaster
Levels of Fukushima radioisotopes in soil did not approach levels known to be harmful to living organisms

Consistent with other monitoring in the area the results of the study indicate that given the trace levels of contamination present the impact of the FDNPP accident on ecosystem and public health in North America will be insignificant. Continue reading Monitoring Fukushima Contamination in Pacific Salmon and Soil in British Columbia →

British Columbia, Cesium, Citizen Science, InFORMing Research, Location, Monitoring, N Pacific, NE Pacific, North America, Peer Reviewed

Update on Fukushima Monitoring Activities in North America: 7 Years On

March 9, 2018 fukushimainform Leave a comment

The Fukushima Daiichi Nuclear Power Plant (FDNPP) and surroundings before the tragic events of March 11, 2011

By Jay T. Cullen

The purpose of this post is to bring the community up to date on monitoring efforts aimed at understanding the impact of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on environmental and public health. This post is part of an ongoing series and will focus on North American monitoring, summarizing work carried out by the Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) project. Seven years since the peak in releases to the environment our project continues to measure environmental levels of radioisotopes that could represent a radiological health risk to living things. InFORM makes measurements of levels in seawater and common marine organisms as consumption of seafood is one of the most likely ways that residents of North America could be exposed to Fukushima derived contamination. Maximum contamination levels in seawater from Fukushima measured in waters offshore and onshore British Columbia and in the Arctic Ocean are about 8 to 10-fold lower than levels present in the North Pacific during the height of atmospheric nuclear weapons testing in the 1950’s and 1960’s. These levels are roughly 1000-fold below the maximum allowable drinking water standards for these isotopes. Levels in marine organisms have not changed significantly since before the disaster. As was reported in 2015 in this comprehensive study by Health Canada and backed up by measurements made by the international scientific community the release of radioisotopes from Fukushima will have no measurable impact on the health of the marine ecosystem in the northeast Pacific nor on public health in North America.

On March 11, 2011 all eyes were on Japan and I was watching too and feeling acutely the loss of life that the earthquake and tsunami brought on the Japanese people. A little later I watched as events at the FDNPP began to unfold and it became clear that a major nuclear accident was underway. I wondered what it meant for me and my family and friends in Victoria, BC Canada. I catalogued all the monitoring data coming in in 2011 I could find from the international scientific community and kept careful watch on the scientific literature. In 2013 I began communicating with the public about what the triple meltdowns at the FDNPP meant for the health of our marine ecosystem and public health because much of the information getting to the public was not scientifically sound, misinformed the public in general and overestimated the risk to people living in North America. The short of the story then was that nothing in the measurements of air, soil and water suggested any significant risk to public or environmental health. But it was clear that many in the public were being mislead by information online. To address the lack of quality information getting to the public I and other scientists in Canada and the USA, non-Governmental Organizations and citizen scientist volunteers put together the InFORM network. This is what we have found so far.

Offshore Monitoring of Seawater Contamination

The levels of radionuclide contamination in seawater is important to understand as the levels that ultimately are found in marine organisms is set by seawater levels. InFORM recently published a peer-reviewed paper in Environmental Science and Technology summarizing our results to date. Offshore levels of Fukushima derived isotopes have peaked and are now decreasing at our westernmost stations 1000-1500 kilometers from the North American coast. The peak levels are well below levels measured in the same waters during the 1950’s and 1960’s when atmospheric nuclear weapons tests were common. The study area is shown in the figure below along with the prevailing currents that brought the contaminated seawater to North America.

Measurements of radiocesium isotopes help scientists determine how much impact Fukushima has had on seawater at any given location on the globe. Off North America levels peaked at about 10 Bq per cubic meter of seawater (a Bq = Becquerel is one decay of an atom per second). This peak contamination is about 10-fold below levels measured here in the middle of the 20^th century and 1000-fold below levels allowed in drinking water in Canada. The figure below shows how Fukushima derived contamination arrived in the upper ~400 meters of seawater from June 2013 until August of 2016.

Progression of Fukushima contamination in the upper 500 meters of seawater over time toward the coast of North America along the Line P times series stations. Data J. Smith (DFO). The coast is on the right hand side of the figure with distance offshore plotted on the x-axis and depth in the ocean on the y-axis. Red values would indicate seawater with cesium concentrations that exceed drinking water standards. The color scheme is on a logarithmic scale.

The figure below shows the change in contamination with time and the levels in comparison to historical levels in the eastern North Pacific Ocean.

Peak levels of contamination from Fukushima in the northeast Pacific at stations P26 (offshore), P16 (intermediate) and P4 (coastal) since 2011 compared with model predictions of Rossi. Insert shows Fukushima contamination relative to weapons testing fallout. Levels at P26 have peaked and are declining reflecting the large releases in the weeks following the meltdown with sustained by much lower releases persisting from that time on.

Levels measured now and predicted to arrive along the coast in the future will not approach levels known to represent a significant risk to the health of marine organisms or human beings.

Coastal Monitoring Efforts by InFORM Citizen Scientists

Since monitoring began coastal seawater concentrations have increased as the Fukushima contamination plume arrives. The first detection of Fukushima contamination at the coast occurred in Feb. 2015 in the coastal community of Ucluelet on the west coast of Vancouver Island. Since that time levels have increased moderately and likely reflect that fact that the mixing of freshwaters coming from the land with the contaminated oceanic waters tend to insulate the coast from higher levels of contamination measured offshore. At the coastal locations contamination levels of human-made isotopes (which are a very small fraction of the radioactive elements in seawater) have increased 2-4 times relative to the pre-Fukushima levels.

Levels of radiocesium detected at the coast of British Columbia since monitoring began in 2014. Regional patterns are shown in the second panel with more ocean exposed (west coast of Vancouver Island and north coast of BC) sites showing more Fukushima derived contamination than sites in the Salish Sea or in sheltered areas of the central coast.

Our coastal ecosystem and food supply are not at risk from these low levels of radioisotope contamination.

Monitoring of Pacific Salmon and Other Marine Organisms

Since 2014 we have collected and analyzed ~100 Pacific salmon and steel head trout per year returning to rivers up and down the BC coast from the Pacific Ocean. There has been no statistically significant increase in the levels of human-made isotopes in the fish since before the Fukushima disaster. The dose of ionizing radiation experienced by consumers of Pacific fish and shellfish is still dominated by the presence of naturally occurring radioisotopes in the Uranium and Thorium decay series (principally 210-Polonium) and remains well below levels that might represent a health risk. Our results are summarized in the following two figures.

Monitoring results for Pacific fish as of September 2017. Approximately 450 fish have been collected over the period 2014-2017. No significant increase in artificial, human made isotopes has been detected.

The ionizing dose from consuming these fish is insignificant relative to other sources of ionizing radiation dose experienced by members of the public in North America. No measurable health impacts are expected.

Dose of ionizing radiation from Fukushima derived isotopes relative to other sources.

Summary

Our intensive monitoring of environmental levels of contamination from Fukushima here in North America indicate that there is insignificant risk to ecosystem or public health resulting from the levels of radioisotopes detected in seawater and marine organisms. A summary of our program results thus far and monitoring of conditions off of Fukushima in Japan are given in the following figure.

Consistent with model predictions and the measurements made by scientists around the globe, the FDNPP accident will not have measurable negative impacts on North America’s marine ecosystems or public health. Levels of contamination are simply too far below those known to represent a threat to wildlife or human health. The InFORM project will continue its monitoring efforts into March 2019 and will continue to report its results and make them available to the public as soon as possible. I am available and happy to answer and questions related to the project, its goals and results. As always on this somber anniversary I think about the incredible loss of life from the tsunami and wish the best for the recovery of Japan’s coastal communities.