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

The Concentration of Radionuclides (Lead-210, Polonium-210, and Cesium-137) in the Muscle of Sardine Fish: a Global Systematic Review, Meta-analysis, and Exposure Assessment

With the increasing use of nuclear technology, concerns about the contamination of water resources with radionuclides and the contamination of seafood are increasing. In the current investigation, a meta-analysis and exposure assessment regarding the concentration of radionuclides, including lead-210 (Pb-210), polonium -210 (Po-210), and cesium-137 (Cs-137) in the muscle of Sardin fish were conducted. In this regard, some databases including Scopus and PubMed were selected to retrieve papers on the concentration of radionuclides in the muscle of Sardin fish from January 2000 to 25 June 2021. The used keywords were polonium-210, natural radioactivity, lead-210, radiocesium, cesium-137, radionuclides, radium-226, seafood, marine foods, fish, sardine fish, sardinella longiceps, and Clupeidae. Also, effective dose (ED) was calculated to estimate carcinogenic risk in Sardine fish consumers. The rank order of radionuclides in the muscle of sardine fish was Po-210 (31.50 Bq/kg) > Pb-210 (3.34 Bq/kg) > Cs-137 (0.48 Bq/kg). Based on level of Pb-210 rank of countries was France (12.00 Bq/kg) > India (4.06 Bq/kg) > Turkey (3.29 Bq/kg) > Spain (1.00 Bq/kg) > Slovenia (0.55 Bq/kg); Po-210 was Turkey (74.96 Bq/kg) > Spain (48.00 Bq/kg) > France (31.500 Bq/kg > India (30.25 Bq/kg) > Slovenia (25.00 Bq/kg) > Kuwait (7.28 Bq/kg) and also, Cs-137 was Japan (1.22 Bq/kg) > Croatia (0.18 Bq/kg) > India (0.23 Bq/kg). The lowest and highest ED of ²¹⁰Po was observed in Kuwait (5.10E-04 msv/y, female) and France (3.14E-01, male); Pb-210, Slovenia (7.24E-05 msv/y, male) and France (1.48E-02 msv/y, female), and Cs-137, Croatia (8.47E-08 msv/y, male) and Japan (2.54E-05 msv/y, female), respectively. The risk assessment shows that the exposed population are at an acceptable range of risk (H < 1 mSv/y).

The concentration and health risk assessment of radionuclides in the muscle of tuna fish: A worldwide systematic review and meta-analysis

Exposure to radionuclides, especially in food, can endanger the health of consumers. In this study, a systematic review and meta-analysis were performed regarding the concentration of radionuclides in tuna fish muscle. International databases including PubMed, Scopus, and Embase were searched to find articles regarding the concentration of radionuclides in tuna fish muscle from 1 January 2000 to 20 February 2021. The lowest and highest concentration of radionuclides was related to Caesium-137 (¹³⁷Cs) and Potassium-40 (⁴ K), respectively. The rank order of radionuclides based on their pooled concentration was ⁴ K (370.157 Bq/kg) > ²¹⁰Po Polonium-210 (26.312 Bq/kg) > ²¹⁰Pb (5.339 Bq/kg) > ²²⁶Ra (4.005 Bq/kg) > ¹³⁷Cs (0.415 Bq/kg). The health risk assessment based on annual effective dose indicates that consumers are at the safe range of health risk (H < 1 mSv/y). The continuous monitoring concentration of radionuclides in seafood and health risk assessment should be recommended.

Radiocaesium in Tricholoma spp. from the Northern Hemisphere in 1971-2016

A considerable amount of data has been published on the accumulation of radiocaesium (¹³⁴Cs and particularly, ¹³⁷Cs) in wild fungi since the first anthropogenically influenced releases into the environment due to nuclear weapon testing, usage and subsequently from major accidents at nuclear power plants in Chernobyl (1986) and Fukushima (2011). Wild fungi are particularly susceptible to accumulation of radiocaesium and contamination persists for decades after pollution events. Macromycetes (fruiting bodies, popularly called mushrooms) of the edible fungal species are an important part of the human and forest animal food-webs in many global locations. This review discusses published occurrences of ¹³⁴Cs and ¹³⁷Cs in twenty four species of Tricholoma mushrooms sourced from the Northern Hemisphere over the last five decades, but also includes some recent data from Italy and Poland. Tricholoma are an ectomycorrhizal species and the interval for contamination to permeate to lower soils layers which host their mycelial networks, results in a delayed manifestation of radioactivity. Available data from Poland, over similar periods, may suggest species selective differences in accumulation, with some fruiting bodies, e.g. T. portentosum, showing lower activity levels relative to others, e.g. T. equestre. Species like T. album, T. sulphurescens and T. terreum also show higher accumulation of radiocaesium, but reported observations are few. The uneven spatial distribution of the data combined with a limited number of observations make it difficult to decipher any temporal contamination patterns from the observations in Polish regions. When data from other European sites is included, a similar variability of ¹³⁷Cs activity is apparent but the more recent Ukrainian data appears to show relatively lower activities. ⁴⁰K activity in mushrooms which is associated with essential potassium, remains relatively constant. Further monitoring of ¹³⁷Cs activity in wild mushrooms would help to consolidate these observations.

Natural radioactivity and total K content in wild-growing or cultivated edible mushrooms and soils from Galicia (NW, Spain)

The radioactive isotope, ⁴⁰K, of naturally occurring potassium (0.012%) is present in the Earth's crust in a low percentage of all potassium, leading to its presence in almost all foodstuffs. The impact of ⁴⁰K activity concentrations was assessed in wild and cultivated edible mushrooms and in growing substrates. Samples were analysed by gamma spectroscopy. In the wild mushroom species, the average activity concentration of ⁴⁰K was 1291 Bq kg^-1 dry weight (dw), approximately 140 Bq kg^-1 fresh weight (fw), with a range of average values per species from 748 in Lactarius deliciosus to 1848 Bq kg^-1 dw in Tricholoma portentosum. The cultivated species presented an average value of 1086 Bq kg^-1 dw; and the soils, compost of cultivation and wood of substrate are 876, 510 and 59.4 Bq kg^-1 dw, respectively. The total K content reached a maximum of 59,935 mg kg^-1 dw in T. portentosum. The transfer factors (TF > 1) suggested that mushrooms preferentially bioconcentrated ⁴⁰K. Cantharellus cibarius, Craterellus tubaeformis, Hydnum repandum and T. portentosum by most TF could be considered as bioindicators of ⁴⁰K. Taking into account that the annual radiation dose of ⁴⁰K due to the average consumption of mushrooms analysed (0.15 μSv/year) is very low, it can be concluded that the consumption of these mushrooms does not represent a toxicological risk for human health. Finally, according to the total K content, from the nutritional point of view, these mushrooms could be considered as a potential source of potassium for the human diet.

Radiocesium concentrations in mushrooms collected in Kawauchi Village five to eight years after the Fukushima Daiichi Nuclear Power Plant accident

Following the Fukushima Daiichi Nuclear Power Plant accident in March 2011, radionuclides such as iodine-131, cesium-134 and cesium-137 were released into environment. In this study, we collected wild mushrooms from the Kawauchi Village of Fukushima Prefecture, located less than 30 km southwest of the Fukushima nuclear power plant, to evaluate their radiocesium (134Cs+137Cs) concentrations and the risk of internal radiation exposure in local residents. 342 mushroom samples were collected from 2016 to 2019. All samples were analysed for radiocesium content by a high-purity germanium detector. Among 342 mushroom samples, 260 mushroom samples (76%) were detected the radiocesium exceeding the regulatory limit of radiocesium (100 Bq/kg for general foods in Japan). The median of committed effective dose from ingestion of wild mushrooms was in the range of 0.015-0.053 mSv in 2016, 0.0025-0.0087 mSv in 2017, 0.029-0.110 mSv in 2018 and 0.011-0.036 mSv in 2019 based on the assumption that Japanese citizens consumed wild mushrooms for 1 year. Thus, our study showed that although radiocesium is still detected in mushrooms collected in Kawauchi village even after 5 to 9 years later, the committed effective dose due to consuming mushrooms was lower than 1 mSv per year. Long-term comprehensive follow-up should monitor radiocesium concentrations in wild mushrooms to support the recovery of the community after the nuclear disaster.

Distribution of 239,240Pu in marine products from the seas around the Korean Peninsula after the Fukushima nuclear power plant accident

In March 2011, an earthquake caused the shutdown of the active reactors at the Fukushima Daiichi Nuclear Power Plant (NPP), with the succeeding tsunami resulting in the release of radioactively contaminated water into the adjacent Japanese coastal waters. Marine biota selected from various trophic levels were collected in Korean coastal waters throughout 2014 and 2015 and their plutonium levels were measured to evaluate the radioactive contamination levels in the marine organisms that constitute the primary seafood diet in the Republic of Korea (ROK). The results showed that the activity concentrations of ^239,240Pu in plankton, macroalgae, mollusks, crustaceans, and cephalopods ranged from 13 to 58, 0.64 to 0.80, 0.94 to 5.40, 0.06 to 0.50, and 0.26 mBq kg^-1 of wet weight (w.w.), respectively. The activity concentrations of ^239,240Pu measured in the muscles of fish varied from 0.09 to 0.30 mBq kg^-1 (w.w.), relatively low values compared to those in other groups regardless of fish species, size, and sampling area. The concentration characteristics of ^239,240Pu in the various organs in the respective marine products revealed that the internal organs showed higher concentrations than the muscle or skin (or exoskeleton). The highest concentration of ^239,240Pu was measured in the viscera of an abalone, which had an activity concentration of 6.31 mBq kg^-1 (w.w.). The concentration factors (CFs) in the >300-μm fraction of plankton and in anchovy, shrimp, and mackerel ranged 67-84% of the International Atomic Energy Agency (IAEA)-recommended values, although the CF in macroalgae was much lower at approximately 5% of IAEA values, suggesting a wide range of ^239,240Pu CF in macroalgae. The mean transfer factor (TF) between macroalgae (0.6-0.8 mBq kg^-1) and abalone (5.4 mBq kg^-1) was estimated to be 7.5, implying that effective Pu transfer occurred between the two species. These figures equate to annual effective doses of ^239,240Pu to Koreans through consumption of macroalgae, shellfish, and fish of 1.8 × 10^-6, 1.4 × 10^-6, and 7.1 × 10^-7 mSv yr^-1, respectively, and a total dose of 3.9 × 10^-6 mSv yr^-1, values that are negligible compared to the annual effective dose limit of 1 mSv yr^-1.

Distribution and accumulation of artificial radionuclides in marine products around Korean Peninsula

We investigated the distributions of the artificial radionuclides ¹³⁷Cs, ^239+240Pu, and ⁹⁰Sr in the various marine products around Korean Peninsula collected in 2015-2017. The activities of ¹³⁷Cs, ^239+240Pu, and ⁹⁰Sr were in the ranges of 12.2-258.4 mBq kg^-1, 0.014-1.879 mBq kg^-1, and 11.3-18.3 mBq kg^-1, respectively. The higher ^239+240Pu (a factor of 10-50) relative to fishes were observed in mollusks. ¹³⁷Cs in fishes were significantly enriched with growths. The calculated concentration factors (CFs) of ¹³⁷Cs, ^239+240Pu, and ⁹⁰Sr in marine products were 7-143, 3-407, and 15-25, respectively. Overall, no noticeable artificial radioactivity was detected in marine organisms when comparing these results with previous data reported before the Fukushima nuclear accident and recommended CF values. The annual effective doses of ¹³⁷Cs, ^239+240Pu, and ⁹⁰Sr by seafood consumption in South Korea were estimated to be 1.1 × 10^-4, 1.6 × 10^-5 and, 2.9 × 10^-5 mSv yr^-1, respectively, which is insignificant relative to that of natural radionuclides.