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

Abstract

Despite the many studies that have shown minimal health risks to individuals living outside of Japan following the Fukushima Nuclear Accident, there are persisting concerns regarding the consumption of Pacific seafood that may be contaminated with radioactive species from Fukushima. To address these concerns, the activity concentrations of anthropogenic 134Cs and 137Cs, as well as naturally occurring 40K, were measured in Pacific salmon collected from Kilby Provincial Park, British Columbia (BC), in 2013 and from the Quesnel River, BC, in 2014 using low-background gamma-ray spectroscopy. In addition, soil samples and a single roof-debris sample were collected and analysed to provide a record of Fukushima-derived contamination in BC. Cesium-134 was not detected in the salmon samples. Cesium-137 was not detected in any of the sockeye or chum samples, although it was detected in all of the Chinook samples. The weighted average (±1σ) 137Cs activity concentration in the Chinook salmon collected in 2013 and 2014 was 0.23 (3) and 0.20 (3) Bq/kg fresh weight, respectively. A conservative annual dose estimate for an adult who consumes the average Canadian quantity of seafood per year, contaminated with radiocesium at the maximum concentrations measured in this campaign, was calculated to be 0.054 μSv per year. Cesium-134 was detected in all but two of the soil samples. A weak positive correlation was observed between presence of 134Cs and of 7Be suggesting that the 134Cs arrived via atmospheric deposition. Cesium-137 was present in every soil sample, although the total radiocesium activity concentrations measured were significantly less than action levels set by Health Canada.