A report on radioactivity measurements of fish samples from the West Coast of Canada

Abstract

Even though many studies have shown that radioactive caesium levels in fish caught outside of Japan were below experimental detection limits of a few Bq kg−1, significant public concern has been expressed about the safety of consuming seafood from the Pacific Ocean following the Fukushima-Daiichi nuclear accident. To address the public concerns, samples of commonly consumed salmon and groundfish harvested from the Canadian west coast in 2013 were analysed for radioactive caesium. None of the fish samples analysed in this study contained any detectable levels of 134Cs and 137Cs under given experimental setting with the average detection limit of ∼2 Bq kg−1. Using a conservative worst-case scenario where all fish samples would contain 137Cs exactly at the detection limit level and 134Cs at half of the detection limit level (to account for much shorter half-life of 134Cs), the resulting radiation dose for people from consumption of this fish would be a very small fraction of the annual dose from exposure to natural background radiation in Canada. Therefore, fish, such as salmon and groundfish, from the Canadian west coast are of no radiological health concern.

Radioactivity studies on farm raised and wild catfish produced in Mississippi, USA

“…Also, a study with an emphasis in understanding the impact of Fukushima nuclear plant incident on marine environment (West coast of Canada), indicated the presence of man-made isotopes of 134 Cs and 137 Cs in fish samples [10]. Another radioactivity study performed on various aquatic organisms within a confined waterbody (for Example Lake) indicated that the levels of radiation uptake in fish are dependent on aquatic habitation and food inclination [11].…”

Fukushima-derived radioactivity measurements in Pacific salmon and soil samples collected in British Columbia, Canada

“…The first was to provide clear and concise information regarding the potential for negative health impacts to the public associated with consuming Pacific salmon potentially contaminated with anthropogenic, e.g., Fukushima-derived radionuclides. Previous studies have attempted to measure the 134 Cs and 137 Cs content in Pacific salmon; 13,14 however, when attempting to measure individual samples, high detection limits have been a limiting factor. A more recent study 15 analysing sockeye salmon collected from Alberni Inlet on the west coast of Vancouver Island, BC, in June of 2014 did detect 137 Cs in five of the ten sockeye salmon sampled.…”

“…Due to the low rate of gamma emission, 210 Po in each sample could not be measured with GEARS. For the dose calculation, the average 210 Po activity concentration in chum salmon collected from the Canadian west coast measured by Chen et al 13 was used in the dose calculation. To convert the activity concentrations in the salmon samples into effective doses received by individuals for the special case of consuming the salmon, dose coefficients from ICRP Publication 119 29 were used.…”

“…1,[7][8][9] As cesium has been previously shown to accumulate in tissues, additional monitoring campaigns have been initiated to investigate the contamination of various freshwater 5,6 and marine 7,[10][11][12][13][14][15] biota, as well as to develop 137 Cs bioaccumulation models in Pacific food-webs. 16 The primary purpose of many radionuclide monitoring campaigns is to describe the degree of contamination in the environment or to provide a dose estimate to the public within a specific region.…”

“…The activity concentrations, as well as the dose contributions from anthropogenic and NORM sources, in each sample were compared. As there was no alpha spectrometer available to measure 210 Po, the NORM isotope responsible for the largest dose to individuals, the 210 Po data from Chen et al 13 were used in the comparison.…”