Concentration of 137Cs and 40K in meat of omnivore and herbivore game species in mountain forest ecosystems of Gorski Kotar, Croatia

Levels of caesium-137 in food of animal origin in Poland

Introduction

Radioactive contamination of the environment is one of the greatest threats after a nuclear accident due to released radionuclides. From a radiotoxicological point of view, the most important radionuclide is caesium-137. Formed mainly during nuclear explosions, caesium-137 can persist in the soil for many years, from where it constantly enters the food chain. One of the elements of ensuring food safety is the monitoring of its radioactive contamination, mainly with radioactive caesium isotopes. The aim of the study was to determine the content of caesium-137 in food of animal origin.

Material and Methods

A total of 1,416 muscle samples from cattle, sheep, pigs, game and fish, as well as chicken eggs and dairy products were examined using gamma-ray spectrometry.

Results

Caesium-137 activities ranged from below the minimum detectable activity concentration (MDC) to over 4,000 Bq/kg wet weight (w.w.). Most often, the values did not exceed the MDC or were in a range below 100 Bq/kg. The exception was the muscle tissue of game animals, especially wild boar, where a significant activity of caesium-137 was recorded, the highest of which was 4,136.8 ± 238 Bq/kg w.w. Committed effective doses determined for each matrix ranged from 0.01 to 0.83 µSv/kg, with the highest value determined for wild boar.

Conclusion

The calculated exposure doses with values well below the accepted low radiation dose (100 mSv) did not indicate any significant amounts of ionising radiation from the food consumed.

Soil fertilisation with 137Cs-contaminated and uncontaminated wood ash as a countermeasure to reduce 137Cs uptake by forest plants

The purpose of present study was to find out whether wood ash with a high pH value and neutralizing capacity reduces ¹³⁷Cs uptake by forest plants many years after the radionuclide fallout. The effects of one-time point fertilisation with ¹³⁷Cs-contaminated and uncontaminated wood ash alone or in combination with KCl on ¹³⁷Cs transfer from soil to young leaves and green shoots of various dwarf shrubs and tree species were examined in a long-term fertilisation experiment (2012-2021) conducted in Bazar mixed forest, around 70 km from Chernobyl nuclear power plant. The results indicated minor effects of soil fertilisation, although there were differences between ¹³⁷Cs uptake by species and years. Soil amendment with ¹³⁷Cs-contaminated wood ash generally did not affect ¹³⁷Cs uptake by young shoots and leaves of plants over the growing season in the first year and only slightly decreased T_ag for ¹³⁷Cs in the following years. The effect of a single application of ¹³⁷Cs-uncontaminated wood ash on reducing ¹³⁷Cs uptake by plants was generally negligible. Application of ¹³⁷Cs-contaminated wood ash in combination with KCl reduced plant ¹³⁷Cs uptake by about 45%, however, such reduction was only significant in some years for bilberry berries, young leaves and green shoots of lingonberry and alder buckthorn. Thus application of wood ash to ¹³⁷Cs-contaminated forest soil many years after radionuclide fallout generally does not reduce ¹³⁷Cs uptake by forest vegetation in a mixed forest ecosystem and this countermeasure should be applied with caution.

90Sr and stable element levels in bones of brown bears: long-term trends in bear populations from Croatia and Poland

The aim of this study was to investigate the temporal trends and geographical differences in ⁹⁰Sr and stable element (Ba, Ca, Mn, Sr, Pb, Zn) levels in the bones of Croatian and Polish brown bear (Ursus arctos) populations. Experimental data suggest that in the decades after nuclear weapon tests and the Chernobyl accident, ⁹⁰Sr bone activity concentrations decreased from 352 to 11 Bq kg^-1 in the Croatian bear population (period 1982-2015) and from 831 to 27 Bq kg^-1 in Polish bears (period 1962-2020). Calculated effective and ecological half-lives were 9 and 13 years for Croatian bears, and 15 and 31 years for Polish bears, respectively. Different temporal trends were noted in levels of Ba, Mn, Pb and Zn between the two countries with majority of bones having lower Pb, Sr and Zn in Croatian than in Polish bears. Estimated values for the soil-to-bear transfer of ⁹⁰Sr were the same order of magnitude in the studied populations. Contrary to this, the estimated transfer of stable Sr was an order of magnitude lower for the Croatian bear population compared to Polish bears. The observed differences in soil-to-bear transfer between stable Sr and ⁹⁰Sr found for Croatian bears might suggest the need for careful consideration on the use of stable Sr data as an analogue for ⁹⁰Sr. To our knowledge, this is the first study that analysed ⁹⁰Sr activity in tissue of brown bears. As such, it provides insight into the fate and behaviour of one of the most relevant anthropogenic radionuclides at the top of the food chain.

Levels of 137Cs in game and soil in Opole Anomaly, Poland in 2012-2020

Once deposited, radiocesium remains in the environment for a long time, and constantly enters the food chain. Over time, game species tend to accumulate ¹³⁷Cs by two orders of magnitude more than farm animals. This occurs especially in places heavily contaminated, thus meat products made out of local game should be treated with caution. One of such areas, known as the Opole Anomaly, is located in South-Western Poland and represents one of most ¹³⁷Cs contaminated regions across Europe after the Chernobyl accident. The aim of the study was to find out the ¹³⁷Cs activity in soil and local game, the value of the soil-to-game aggregated transfer factor and to assess the effective dose of the ionising radiation (E_eff) received by consumers of local game meat in years 2012-2019. We examined meat of three common game species: red deer, roe deer and wild boar for ¹³⁷Cs activity. ¹³⁷Cs activity in meat samples ranged from 0.14 to 592 Bq kg^-1. The aggregated transfer factor (T_ag) in game ranged from 0.006 to 0.01 m² kg^-1 f.w. for wild boar, 0.005-0.008 m² kg^-1 f.w. for roe deer, and 0.003-0.004 m² kg^-1 f.w. for red deer. The effective dose received by people who regularly consume local game meat ranged from less than 14.2 µSv y^-1 to 134 µSv y^-1, depending on the amount of differently contaminated game meat consumed annually. Even those for whom game is the only source of meat, consumption of wild boar along with local mushrooms and bilberries will, since 2012, not exceed the regulation limit of ¹³⁷Cs at the level of 1 mSv y^-1. By the best of our knowledge this is the first study regarding ¹³⁷Cs activity in game and risk assessment from the most contaminated "post-Chernobyl" area in Poland.

Proximate Chemical Composition, Fatty Acid Profile, and Lipid Qualitative Indices of Brown Bear Meat

Although game meat quality has been under the spotlight in numerous studies, the quality of brown bear (Ursus arctos) meat is still unknown. The aim of this study was to determine the effects of sex and age on the proximate chemical composition, fatty acid profile, and lipid indices of brown bear meat. Nine (n = 9) females and nine (n = 9) males were hunted during the Croatian spring hunting period in 2018. Based on age, bears were divided into two groups: <3 years (n = 9; five females and four males) and 4–6 years (n = 9; four females and five males). For analysis purposes, samples of M.semimembranosus were collected. Age was shown to have an effect on the traits analyzed, while sex-related differences were not found. Brown bear meat has a high fat content (average 6.12%), especially in older bears (~9%). The contents of protein, dry matter, and ash were similar to those of other game species. Monounsaturated fatty acids made up approximately 50% of all fatty acids, with the most abundant being C18:1n-9. More favorable profiles of essential polyunsaturated fatty acids were found in younger bears. The ratio of polyunsaturated and saturated fatty acids was closer to the recommended ratio than the ratio of n-6 and n-3 polyunsaturated fatty acids, and lipid indices were favorable. Further research is needed to determine seasonal changes in brown bear meat quality.

Barbary sheep tissues as bioindicators of radionuclide and stabile element contamination in Croatia: exposure assessment for consumers

Muscle, liver and kidney of 21 Barbary sheep (Ammotragus lervia) from Mosor Mountain, Croatia, were sampled to quantify the activity of caesium and potassium radionuclides and five toxic and ten essential stabile elements in order to establish reference values for this species and to evaluate the potential of Barbary sheep tissues to reflect environmental pollution. We also assessed seasonal diet (botanical composition and dry matter content) of Barbary sheep based on analyses of a rumen content of culled animals. None of the 19 plant species (mostly grasses) identified as part of the Barbary sheep diet is known as a stabile element or radionuclide hyperaccumulator. Measured levels reflected low environmental pollution with arsenic, cadmium, mercury and lead, with levels generally less than those reported for wild herbivorous ungulates. Methodological differences (detection limit of elements in muscle) were shown to hamper interpretation and comparison of the Toxic Contamination Index (TCI) values with those published for other species. There was no homeostasis disturbance of trace elements in Barbary sheep, either due to inadequate intake via food or as an adverse effect due to a high toxic metal(loid) burden. Consumption of the muscle and liver of wild Barbary sheep can be considered safe for the health of adult consumers regarding toxic metal(loid)s and radioactive caesium, though the liver should be avoided as a food item in vulnerable population groups due to the possible adverse effects of cadmium and lead. Otherwise, muscle and liver are a rich source of copper, iron, selenium and zinc for consumers and, as such, can benefit the overall dietary intake of essential elements.

Monitoring of 137CS and 40K in the Levice District, Southern Slovakia

The contamination of the environment, soil and meat of wild animals with radionuclides can negatively affect human health. The aim of our study was to analyse the risk arising from post-Chernobyl contamination of the meat of wild boars (Sus scrofa) originating from the district Levice, southern Slovakia, with the radioactive artificial element 137Cs. The level of natural radionuclide 40K was also determined. We examined altogether 45 samples obtained from 9 wild boars hunted in this area during the period of 2013—2015. From each animal we collected and analysed samples from the thigh, stomach contents, stomach muscles and skin. We also examined samples of soil from the locations where these animals were shot. The activity values of radioactive caesium 137Cs determined in this study were very low and therefore the consumption of wild boar meat originating from this location presents no risk to human health.

Fat tissue is not a reservoir for radiocesium in wild boars

Meat of wild boars is not only known for high ¹³⁷Cs activity concentrations but also for the remarkable constancy of these levels. Even decades after the Chernobyl accident, the ¹³⁷Cs levels in wild boar meat in Central Europe have not declined but even partly increased. In the present study, we investigated an unusual hypothesis for this very unusual phenomenon: may the boars’ fat tissue act as a reservoir for radiocesium? We investigated fat and muscle tissues of four wild boars in Western Germany and found that the ¹³⁷Cs concentrations in fat were in the range of 10–30% of the respective activities in muscle tissue. Hence, the hypothesis was refuted.

The Time-Dependent Transfer Factor of Radiocesium from Soil to Game Animals in Japan after the Fukushima Dai-ichi Nuclear Accident

Since the Fukushima Dai-ichi accident, monitoring of tissues from hunted game animals ensures compliance with the standard food limits for radionuclides in Japan. We quantified the transfer of (137)Cs from contaminated land to game animals using the Aggregated transfer factor (Tag = activity concentration in meat [Bq kg(-1) fw]/amount in soil [Bq m(-2)]) of (137)Cs for Asian black bear, wild boar, sika deer, green pheasant, copper pheasant and wild duck, collected between 2011 and 2015. Open data sources were used from Fukushima, Miyagi, Ibaraki, Tochigi, and Gunma prefectures. Our initially compiled data showed that the maximum reported (137)Cs activity concentration in wild boar after the Fukushima Dai-ichi accident were lower than those reported after the Chernobyl accident. The geometric mean Tag values (m(2)kg(-1) fw) of (137)Cs in 2015 for Asian black bear, wild boar, sika deer and copper pheasant were similar (1.9-5.1) × 10(-3) while those for green pheasant and wild duck were about 1 order of magnitude lower at (1.0-2.2) × 10(-4). Effective half-lives were 1.2-6.9 y except for sika deer and copper pheasant where no decreases were found. In contrast to the Chernobyl accident, no seasonal change occurred in the meat (137)Cs activity concentrations of the wild animals during the study period.

137Cs monitoring in the meat of wild boar population in Slovakia

Currently, due to the elapsed time and the nature of the Chernobyl accident, the only artificial radionuclide present in the soil is 137Cs, with a physical half-life conversion of 30.17 years. The 137Cs is quickly integrated into a biological cycle, similar to potassium. Generally, radionuclides are characterized by their mobility in soil. Contamination of materials and food by radionuclides represent a serious problem and has a negative impact on human health. The threat of international terrorism and the inability to forestall the impact of natural disasters on nuclear energetic (Fukushima accident), are also reasons for continuous monitoring of food safety. According screening measurement performed in European countries, high radioactivity levels were reported in the wild boars muscles from Sumava (Czech Republic). Seasonal fluctuation of 137Cs activity in the wild boar meat samples was observed in the forests on the southern Rhineland. Monitoring of 137Cs activity in the wild boar meat samples in the hunting grounds in Slovakia was initiated based on the reports on exceeding limits of the content of radiocaesium in the meat of wild boar from the surrounding countries. The aim of this study was to determine the 137Cs post Chernobyl contamination of wild boars population in different hunting districts of Slovakia during 2013 - 2014. A total of 60 thigh muscle samples from wild boars of different age categories (4 months - 2 years) were evaluated. 137Cs activity was measured by gamma spectrometry (Canberra). Despite the fact Slovakia is closer to Chernobyl as Czech Republic and Germany, the 137Cs activity measured was very low and far below the permitted limit. The highest radiocaesium activity level measured in muscle was 37.2 Bq.kg-1 ±4.7%. Wild boar originated from Zlate Moravce district. The measurement results show, that 137Cs contamination levels of game in Slovakia are low. Radiocaesium activity in examined samples was very low and therefore consumption of wild boar meat does not represent a health risk problem.

Artificial environmental radionuclides in Europe and methods of lowering their foodstuff contamination – a review

This review discusses the consequences of the food chain contamination with radionuclides, especially focusing on the radiocaesium impact after the Chernobyl nuclear accident. In particular, the137Cs isotope still represents a risk. Until present it is still detectable in the meat of game animals, especially in wild boar, but also in elk and reindeer. Although the occurrence of highly contaminated foods in most of Europe is currently limited, along the German-Czech border (the Šumava Region) the activity concentration of the137Cs isotope in the meat of wild boar exceeds the acceptable limit several times. Additionally, the article describes simple processing technologies (cooking, pickling etc.) that lead to reduction of radionuclides in contaminated food.

Dietary items as possible sources of (137)Cs in large carnivores in the Gorski Kotar forest ecosystem, Western Croatia

The mountain forest ecosystem of Gorski Kotar is distant from any significant sources of environmental pollution, though recent findings have revealed that this region is among the most intense (137)Cs contaminated area in Croatia. Therefore, the aim of this study was to investigate (137)Cs and (40)K load in three large predator species in the mountain forest ecosystem. Radionuclides mass activities were determined by the gamma-spectrometric method in the muscle tissue of brown bear (47), wolf (7), lynx (1) and golden jackal (2). The highest (137)Cs mass activity was found in lynx (153 Bq kg(-1)), followed by brown bear (132 Bq kg(-1)), wolf (22.2 Bq kg(-1)), and golden jackal (2.48 Bq kg(-1)). Analysis of 63 samples of dietary items suggests that they are not all potentially dominant sources of (137)Cs for wildlife. The most important source of radionuclides for the higher parts of the food-chain from the study area were found to be the mushroom species wood hedgehog (Hydnum repandum), with a transfer factor TF of 5.166, and blueberry (Vaccinium myrtillus) as a plant species (TF=2.096). Food items of animal origin indicated higher mass activity of radionuclides and therefore are possible moderate bioindicators of environmental pollution. The results also revealed that possible unknown wild animal food sources are a caesium source in the study region, and further study is required to illuminate this issue.

137Cs in the meat of wild boars: a comparison of the impacts of Chernobyl and Fukushima

The impact of Chernobyl on the ¹³⁷Cs activities found in wild boars in Europe, even in remote locations from the NPP, has been much greater than the impact of Fukushima on boars in Japan. Although there is great variability within the ¹³⁷Cs concentrations throughout the wild boar populations, some boars in southern Germany in recent years exhibit higher activity concentrations (up to 10,000 Bq/kg and higher) than the highest ¹³⁷Cs levels found in boars in the governmental food monitoring campaign (7900 Bq/kg) in Fukushima prefecture in Japan. The levels of radiocesium in boar appear to be more persistent than would be indicated by the constantly decreasing ¹³⁷Cs inventory observed in the soil which points to a food source that is highly retentive to ¹³⁷Cs contamination or to other radioecological anomalies that are not yet fully understood.

The effect of environmental remediation on the cesium-137 levels in white-tailed deer

Due to activities involving nuclear energy research during the latter half of the 1900 s, environmental contamination in the form of elevated cesium-137 levels was observed within the Brookhaven National Laboratory, a US Department of Energy facility. Between the years 2000 and 2005, the laboratory carried out a major soil cleanup effort to remove cesium-137 from contaminated sites. In this study, we examine the effectiveness of the cleanup effort by comparing the levels of cesium-137 in the meat of white-tailed deer found within and around the laboratory. Results suggest that the cleanup was effective, with mean concentration of cesium-137 in the meat from within the laboratory decreasing from 2.04 Bq/g prior to 1.22 Bq/g after cleanup. At the current level, the consumption of deer would not pose any human health hazard. Nevertheless, statistically higher levels of cesium-137 were detected in the deer within the laboratory as opposed to levels found in deer 1 mi beyond the laboratory site.