Evaluation of abundance of artificial radionuclides in food products in South Korea and sources.

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Citation abstract

Food samples are collected nationwide from January 2016 to February 2017 and their contents of artificial radionuclides are measured to address the growing concerns regarding the radioactive contamination of food products in Korea. Specifically, 900 food samples are collected for this study and their contents of representative artificial radionuclides 134 Cs, 137 Cs, 239,240 Pu, and 90 Sr are analyzed. The analysis shows that the activity concentrations of 137 Cs in fish range from minimum detectable activity (MDA) to 340 mBq/kg of fresh weight. The concentration factor (CF) determined for 137 Cs as a measure of its bioavailability is calculated to be ca. 74 and found to be very similar to that (100) recommended by the International Atomic Energy Agency. With an MDA of <0.221 mBq/kg, the results reveal that 239,240 Pu values in fish are below the MDA. The activity concentrations of 137 Cs and 90 Sr are lower than the MDA in both shellfish and seaweed, while the activity concentrations of 239,240 Pu in shellfish range from 0.26 to 2.18 mBq/kg, and for seaweed samples range from 2.07 to 3.38 mBq/kg. The atom ratios of 240 Pu/ 239 Pu in shellfish caught at the Korean coast vary from 0.209 to 0.237, with a mean of 0.227. The higher 240 Pu/ 239 Pu atom ratio determined in shellfish is thought to be caused by the plutonium transported from the Pacific Proving Grounds rather than other sources such as the Fukushima nuclear power plant accident. The activity concentrations of 137 Cs in mushrooms are found to vary from 1.0 to 21.4 Bq/kg, with the highest concentrations observed in the Oak (shiitake) and Sarcodon asparatus. 134 Cs is detected in three mushroom specimens collected from Jeju Island and about 3-3.6% of 137 Cs present in the wild mushrooms native to the Jeju Island are introduced as a result of the Fukushima nuclear plant accident. The annual effective doses of 137 Cs received through consumption of mushrooms and fish are 2.0 × 10 -4 mSv yr -1 and 3.9 × 10 -5 mSv yr -1, and those values are negligible compared to the annual effective doses limit of 1 mSv yr -1.