No Fukushima contamination has been found in any of 12 fish sampled and tested by the Alaska Department of Environmental Conservation (DEC) in 2017. Sampled between March and July 2017, the Pollock (Gadus chalcogrammus), Pacific Cod (Gadus macrocephalus), Halibut (Hippoglossus stenolepis), Herring (Clupea pallasii), and salmon (Sockeye (Oncorhynchus nerka), Chinook (O. tshawytscha), and Chum (O. keta)) were sampled from waters off the the Southeast panhandle to the Bering Sea.
Continue reading No Fukushima Contamination in Alaskan Fish – 2017 Update
No Fukushima contamination was found in any of the 14 fish Alaskan fish samples that were collected between February and September 2016, according to the Alaska Department of Environmental Conservation. The results, released on the Alaksa DEC website, show that the sampled herring, cod, and pollock, halibut, and salmon did not have any detectable levels of 131I, 134Cs (the Fukushima fingerprint radionuclide with a half-life of ~2 years) or 137Cs in the tissues. These samples were from across Alaskan waters from Southeast to Bristol Bay and the Aleutian archipelago and the Bering Sea. Results from 2016 are similar to their results from 2015 and are part of the network of institutions monitoring for Fukushima radiation in marine waters and seafoods.
The average minimum detectable concentrations for these Alaskan samples on this gamma spectrometer were 63.7 Bq kg-1, 2.1 Bq kg-1, and 1.9 Bq kg-1 respectively for 131I 137Cs, and 134Cs. While InFORM does not analyze for 131I, those detection thresholds for cesium are 2-3 times higher than are typical for our biotic monitoring program. This may be due to either a smaller sample size or a shorter time in the gamma spectrometer for the Alaskan samples, but the result remains that levels are well below those where intervention is needed (intervention levels for 131I = 170 Bq kg-1 and 134Cs + 137Cs = 1200 Bq kg-1 according to the US Food and Drug Administration). InFORM monitoring in 2016 found 9 salmon (out of 123) from BC and Yukon rivers with detectable levels (where the minimum detectable concentrations were less than 1 Bq kg-1) of 137Cs after a six hour detector run. These nine samples are currently being freeze-dried for an extended, 2 week long, detection run. Results from this additional analysis are expected probably mid-late spring 2017.
An interesting aspect of these 2016 Alaskan samples is that this was the first time a field-deployable gamma spectrometer has been sent by the US Food and Drug Administration to a site for local analyses of samples. Data from the spectrometer were then electronically sent to FDA scientists for analysis. The thought is that this model could be used in the event of nuclear emergency to allow for more rapid analyses of environmental samples.
Alaska DEC will continue monitoring fish samples for Fukushima radiation for at least 2017 and possibly beyond.
by Jay T. Cullen
The purpose of this post is to report measurements of radioactivity in fish caught off the west coast of Canada based on the work of InFORM team member Dr. Jing Chen. A collaborative effort between Health Canada, Department of Fisheries and Oceans Canada, and the University of Victoria was published in May 2014 in the peer-reviewed, open-access scientific journal Radiation Protection Dosimetry (link). The authors examined the activities of cesium radioisotopes (134-Cs half-life ~2 years and 137-Cs half-life ~30 years) that were released in large quantities due to the triple reactor meltdowns at Fukushima Dai-ichi Nuclear Power Plant in 2011 as well as a naturally occurring polonium isotope (210-Po) that can pose radiological health concerns for human consumers of marine fish. Samples of chum and coho salmon, halibut, sablefish and spiny dogfish were analyzed and none were found to contain detectable levels of Fukushima derived radionuclides. Radiation doses to human consumers were determined by assuming a conservative worst case scenario where Cs isotopes were present at detection limits of the measurement and found to be 18 times lower than doses attributable to the naturally occurring, alpha-emitter 210-Po. The authors conclude that the radiation dose from Fukushima derived isotopes present in fish caught in Canadian waters represent a very small fraction of the annual dose from exposure to natural background radiation. Based on these measurements, at present, Fukushima derived radionuclides in fish do not represent a significant radiological health risk to Canadians. Continue reading Looking For Fukushima Radionuclides in Fish Caught Off the West Coast of Canada