225 8 Radionuclides in Foodstuffs and Food Raw Material Pascal Froidevaux, Tony Dell, and Paul Tossell CONTENTS 8.1 Introduction 226 8.2 Sources of Radioactivity 226 8.2.1 Natural Sources 227 8.2.2 Anthropogenic Sources 229 8.3 Pathways of Transfer to Food 232 8.3.1 Food Groups and Radionuclides of Interest 233 8.3.1.1 Milk 233 8.3.1.2 Total Diet Samples 234 8.3.1.3 Naturally Occurring Radionuclides 235 8.3.1.4 Free Foods 236 8.3.1.5 Freshwater Foods 237 8.3.1.6 TENORM Radionuclides 238 8.3.1.7 Fish and Shellfish 239 8.3.1.8 Indicator Materials 239 8.4 Monitoring Radioactivity in the Food Chain 240 8.4.1 Who/What Drives Legislation? 240 8.4.2 Intervention-Level Guidelines 244 8.4.3 Effects of Processing 244 8.4.4 Recommendations for Food Monitoring Programs 245 8.4.4.1 Provide Real-Time Monitoring Data to Detect the Presence of Radionuclides 246 8.4.4.2 Provide Public Reassurance That the Food Being Consumed Is Safe to Eat 247 8.4.4.3 Produce Reconstructive Dose Assessments 247 8.4.4.4 Aid in the Estimation of Prospective Dose Assessments 248 8.4.4.5 Emergency Response 248 8.4.5 Quality Assurance 248 DK594X_book.fm Page 225 Tuesday, June 6, 2006 9:53 AM © 2007 by Taylor & Francis Group, LLC 226 Radionuclide Concentrations in Food and the Environment 8.5 Introduction to Special Situations 250 8.5.1 Chernobyl 250 8.5.2 Sellafield and the Cumbrian Coast 252 8.5.3 Techa River 255 8.5.4 Cardiff, Wales 256 8.5.5 Brazil Nuts 259 8.6 Future Issues 261 References 262 8.1 INTRODUCTION Everybody needs to eat food to survive and develop. Food can become contam- inated with a wide range of pollutants including radioactivity. The goal of this chapter is to show the importance of monitoring food for levels of radioactivity. We will look at the important sources of radioactivity, both natural and anthropogenic, and relevant transfer pathways through the food chain, identifying the combinations of food groups and radionuclides of most interest. In order to assess the impact of food contamination exposure on the popula- tion, we will develop the concept of radioactivity monitoring programs for food, including important driving forces such as developing international safety and trade legislation, and public reassurance. We show that data generated can be used for both retrospective and prospective dose assessments, and the effect that food processing methods may have on these doses. In addition to what might be regarded as routine programs, we will look at examples of special investigations, such as postaccident monitoring of food. 8.2 SOURCES OF RADIOACTIVITY Radioactivity has two different origins in the environment. Some radionuclides are naturally present in soil, rocks, underground water, oceans, and the atmo- sphere. Their mobility and potential transfer to the food chain are directly linked to parameters such as their chemical form, redox conditions of the environment, alteration of minerals and hydrogeological conditions. Chemistry within the rhizosphere is critical in the transfer of radioactivity from soils to plants [1,2]. Air mass exchange within the atmosphere is also a key parameter for radionu- clides produced by cosmic rays in the atmosphere. For technologically enhanced naturally occurring radioactive materials (TENORMs), both soil mineralogy and human parameters (e.g., fertilizers, petroleum or mining industries) are of impor- tance when considering the transfer of radioactivity to the food chain. The distribution of anthropogenic radionuclides in the environment is less associated with the mineralogy of soils, and depends mostly on the presence of authorized or accidental releases from the nuclear power industry, military facil- ities, and nuclear weapons tests. DK594X_book.fm Page 226 Tuesday, June 6, 2006 9:53 AM © 2007 by Taylor & Francis Group, LLC Radionuclides in Foodstuffs and Food Raw Material 227 While naturally occurring radionuclide distribution can be seen as approximately homogeneously distributed on Earth, with the exception of ore deposits, anthro- pogenic radionuclides have been distributed along plumes of contamination. In that case, sources of contamination are of the utmost importance as far as transfer of radionuclides to the food chain is concerned. For instance, Bundt et al. [3] show that 137 Cs from the Chernobyl accident has been enriched in flow paths present in soils due to heavy rain and water runoff during the deposition. Con- sequently enrichment of radionuclides during wet deposition in a part of the soil where roots are present in higher density led to higher activity in plants than with dry deposition. When looking at the presence of radioactivity in food, emphasis should be placed on the sources of radionuclides or dispersion in the environment. 8.2.1 N ATURAL S OURCES Our planet and its atmosphere contain many different naturally occurring radio- active materials (NORMs). Most cosmogenic radionuclides are produced from spallation of atoms in the atmosphere due to bombardment by cosmic rays. Of all the radionuclides produced in the atmosphere, only 14 C, 3 H, and to a lesser extent 7 Be are of any significance in foodstuffs, these three radionuclides being easily transferred to the food chain. The residence time of a radionuclide produced by cosmic rays in the atmosphere is about 1 year before gravitational settling and precipitation processes deposit it on the ground. Due to its short half-life (53 days), 7 Be is only observed in grass and leaves following direct deposition (e.g., leafy vegetables). In Switzerland, 7 Be activity in grass ranges from 50 to 400 Bq/kg dry weight, with higher activities measured in alpine grass than in lowland grass. 14 C (5500 yr) is rapidly oxidized to 14 CO, then to 14 CO 2 , and incorporated to all living beings, first as a result of photosynthesis. 14 C reference activity in all living organisms is close to 0.23 Bq/g carbon. As a result of the introduction of large amounts of fossil carbon in the atmosphere from burning fuel and oil, the ratio of 14 C to nonradioactive carbon ( 12 C) has been reduced starting from the second part of the 19th century [4]. The detonation of hundreds of nuclear weapons during the 1960s led to a sharp increase in the atmospheric 14 C inventory, roughly doubling the previous ratio to 0.5 Bq/g carbon. Since the signing of the Nuclear Test Ban Treaty, which stopped the testing of nuclear bombs in the atmosphere, a regular decrease in 14 C activity has been observed, with a “half-life” of about 13.5 yr. At the present time, and without the input of 14 C associated with nuclear power plant operations, the 14 C activity ratio has returned to pretesting levels [5]. However, 14 C is also a by-product of nuclear energy production. Where atmospheric releases from the nuclear power industry occur, an increase in the 14 C/ 12 C ratio in vegetation has been locally observed [6]. 40 K is present in all soils as an isotope of stable potassium and is transferred, as an alkaline cation, to the food chain. Soils of Switzerland contain 40 K activities from 250 to 1000 Bq/kg dry weight, while activities in grass range from 400 to 1300 Bq/kg dry weight. Milk contains high levels of potassium (up to 1.4 g/l) DK594X_book.fm Page 227 Tuesday, June 6, 2006 9:53 AM © 2007 by Taylor & Francis Group, LLC 228 Radionuclide Concentrations in Food and the Environment and 40 K activity is close to 45 Bq/l [7]. The activity of wheat cultivated in lowland Switzerland is 116 ± 10 Bq/kg. Thus high activities of 40 K found in food lead to a body activity due to 40 K of 4.4 kBq for the reference man (70 kg), and is mainly located in muscles [8]. Accordingly 40 K represents the largest contributor to internal exposure to radioactivity by ingestion of food. Soils contain three series of naturally occurring heavy radionuclides. The 232 Th series and the 238 U series are of most importance, the 235 U series being less important because of the low natural 235 U content of uranium ores (0.72%) and its long half-life (7.04 × 10 8 yr). Virtually all soils contain uranium and thorium. Typical 238 U activity is close to 30 Bq/kg [9]. Soil to plant transfer factors for uranium and thorium are very low, so root uptake is not the main pathway of uranium and thorium in the food chain, even if their progeny can find their way to food in larger quantities [10]. In an investigation of the phytoremediation of uranium contaminated sites, Ebbs [11] suggested that some plants preferentially accumulate uranium, but to no more than 3.5 µ g/plant (12 Bq/plant). In Switzer- land, the range of values for uranium in grass is 0.25 to 14 Bq/kg dry weight [7]. Cows inadvertently eat soil while grazing and grass can be contaminated by soil particles. However, the authors showed that milk (less than 5 mBq/l) and cheese (less than 30 mBq/kg) contain very low levels of 238 U. Analysis of the 234 U/ 238 U ratio suggests that the contamination of milk and cheese by uranium originates from the water that the cows drink, not the grass they eat. It was assumed that uranium dissolved in water is more readily available for absorption through the gastrointestinal tract than uranium contained in grass, either as the result of root uptake or by adherent soil particles. Nevertheless, source-dependent bioavailabil- ity is an important factor in determining the radioactivity contamination of rumi- nant-derived food products [12]. Technologically enhanced naturally occurring radioactive materials are pro- duced through various industrial operations and these may lead to discharges to the environment. One of the major contributions of radiological exposure to man from TENORMs is mining and mill tailings, where enhanced concentrations of NORMs are observed [13]. Thus enhanced accumulation of uranium in forage or in drinking water could lead to enhanced uranium in milk and beef [14]. In the European Commission MARINA II Study Part II, Betti et al. [15] suggested that, in the 1980s, the radiation dose rates to marine biota in the region around a phosphate plant on the northwest coast of England were as high as those near the Sellafield reprocessing plant due to its own discharges. It was estimated that since 1981, the total discharges from the phosphate industry of the α emitters 226 Ra and 210 Po to the North Sea and the English Channel amounted to 65 TBq. Since the 1990s, discharges from the phosphate industry have decreased, being replaced by discharges from the oil and gas industry, mostly as releases of contaminated water by offshore platforms. As a member of the 238 U series, 226 Ra is associated with uranium deposition, but, as a member of the alkaline earth group, its behavior is similar to that of calcium. Thus 226 Ra can be transferred to food by similar mechanisms to calcium. 226 Ra has been used throughout the 20th century. Its radiotoxicity was established DK594X_book.fm Page 228 Tuesday, June 6, 2006 9:53 AM © 2007 by Taylor & Francis Group, LLC Radionuclides in Foodstuffs and Food Raw Material 229 in 1924, when dentist Theodore Blum noted the prevalence of “radium-jaw” disease among radium dial painters [16]. 226 Ra used in industrial products may still be a source of environmental contamination (e.g., contaminated buildings, waste disposal). The petroleum industry is a major source of 226 Ra dispersal to the environment [17]. In the geological process of oil formation, 226 Ra, being slightly soluble, accumulates on the liquid phases of subsurface water formation. When brought to the surface, some 226 Ra precipitates with barium sulfates and carbonates, yielding concentrated levels of radium in scales and sludges. Smith et al. [17] calculated that disposal of radioactive petroleum waste in municipal solid waste landfills would result in exposure to the public of a small fraction of the recommended 1 mSv/yr. 8.2.2 A NTHROPOGENIC S OURCES Since the discovery of nuclear fission, a large number of anthropogenic radionu- clides have been produced. Some of them are produced due to fission of nuclei, like 137 Cs, 131 I, or 90 Sr, while others are produced by activation of uranium fuel (e.g., plutonium isotopes) or reactor components (e.g., 60 Co) by neutrons. The release of anthropogenic radionuclides in the environment follows different path- ways, all having their importance in the way radioactivity finds its way to the food chain. The production of electricity from nuclear power plant is responsible for the introduction of anthropogenic radioactivity into the environment through authorized discharges, accidental discharges such as the Chernobyl accident, and to a lesser extent unauthorized discharges. The production and testing of nuclear weapons is responsible for both localized contamination, due to onsite incidents, and global dispersion of radioactivity from fallout. Fallout from weapons tests occurred for several months following each atmospheric test as wet and dry deposition. For instance, rainfall and snowfall deposition rates are higher in moun- tainous areas, and deposition of 137 Cs, 90 Sr, and 239/240 Pu is always higher in mountainous areas than in lowland areas [7,18,19]. A significant relationship has been observed between 137 Cs deposition and rainfall rates [20–22]. The transfer of radioactivity to food has been observed as a consequence of some of the previously discussed sources. Nuclear weapons tests released large quantities of plutonium, 90 Sr, and 137 Cs throughout the Northern Hemisphere, with maximum levels found around 40˚N to 50˚N latitude [23]. In Switzerland, par- ticular attention has been paid to the highly radiotoxic 90 Sr since the beginning of the nuclear era [24]. As milk and dairy products constitute an important part of the diet of the Swiss population, it was recognized that 90 Sr, an alkaline earth cation, follows the same metabolic pathways as calcium, and represents the main contributor to the internal dose by fission products. Since the beginning of the 1950s, milk samples, milk teeth, and vertebrae have been collected yearly for 90 Sr determination. The results presented in Figure 8.1 show a large increase in 90 Sr activity in milk samples during the 1960s, corresponding to nuclear testing in the atmosphere. The 90 Sr activity profile in milk teeth matches that of milk, illustrating that 90 Sr present in the environment has been transferred to the food DK594X_book.fm Page 229 Tuesday, June 6, 2006 9:53 AM © 2007 by Taylor & Francis Group, LLC 230 Radionuclide Concentrations in Food and the Environment chain, then to milk teeth through breast-feeding. Since the signing of the Limited Nuclear Test Ban Treaty in 1963, 90 Sr activity has decreased exponentially, with an apparent biological half-life of about 12 years in milk and 10 years in milk teeth. After the Chernobyl accident, it was observed that the 90 Sr activity of milk and dairy products in Switzerland doubled from 0.1 to 0.2 Bq/l during the first months after the accident [25]. Unexpectedly, 90 Sr activity in Swiss milk returned to its pre-Chernobyl level after just a few months. Rapid migration of Chernobyl- derived 90 Sr in the deepest parts of the soil profile was observed, indicating that the chemical form of the Chernobyl radiostrontium was more mobile than radio- strontium from nuclear weapons test fallout [26]. 137 Cs in the environment results from two main deposition pathways. Fallout from nuclear weapons tests spread large quantities of radiocesium. The average deposition in the Northern Hemisphere ranges between 2000 and 5000 Bq/m 2 (reference date 2000), with greater activities found in highlands than in lowlands. The Chernobyl accident approximately doubled the deposition of radiocesium in large parts of western Europe. Levels as high as 85 kBq/m 2 were recorded in Sweden, while the Tessin region in Switzerland and Bavaria in Germany received up to 45 kBq/m 2 [27]. Furthermore, reconcentration phenomena as a result of soil particle runoff during heavy rainfall episodes yielded hot spots with very high activity [18,28]. The 137 Cs contamination of food following the Chernobyl accident was very dependent on meteorological conditions during the passage of the contaminated cloud. Following a release of radioactivity in the environment, it is very important to determine the bioavailability of the most radiologically significant radionuclides. FIGURE 8.1 Average 90 Sr activity (in Bq/g of calcium) in milk and milk teeth from 1950 to 2000 in Switzerland. Activity in milk teeth is reported to the year of birth. 0 0.5 1 1.5 2 2.5 1945 1955 1965 1975 1985 1995 2005 Year Bq/g Ca in milk 0.0 0.1 0.2 0.3 0.4 Bq/g Ca in milk teeth Milk Milk teeth DK594X_book.fm Page 230 Tuesday, June 6, 2006 9:53 AM © 2007 by Taylor & Francis Group, LLC Radionuclides in Foodstuffs and Food Raw Material 231 For instance, it has been demonstrated that the availability of the initial deposit of Chernobyl fallout for transfer to grazing animals was considerably less than the value for radiocesium incorporated into grassy herbage via root uptake. Beresford et al. [12] reviewed the source-dependent bioavailability in determining absorption from the ruminant gastrointestinal tract for the most significant radi- onuclides ( 137 Cs, 90 Sr, and 131 I). The review showed that absorption of radioiodine through the gastrointestinal tract is complete whatever the source. 90 Sr absorption is very dependent on the calcium requirement of the animal, but not on the source, while radiocesium absorption is very source dependent. Plutonium’s absorption coefficient is very low (1.21 × 10 4 ) compared to 137 Cs (0.2 to 0.8), but might be source dependent. However, Froidevaux et al. [7] were unable to detect plutonium isotopes in cheese produced in western Europe (less than 0.3 mBq/kg), showing that absorption of plutonium from ingested soil (maximum activity of 3 Bq/kg) through the gastrointestinal tract is very low and does not represent a significant contribution to internal exposure. Directly after a gaseous radioactive contamination incident (e.g., the Cher- nobyl accident), contamination of foodstuffs is essentially the result of vegetation interception of the deposition (i.e., direct surface contamination). The combined effect of the radioactive decay (for short half-life radionuclides), weathering effects, dilution due to biomass growth, and transfer into nonedible or unused parts of the plant, and increasing fixation of radionuclides in soil account for an apparent “half-life” of the radioactivity that is usually less than 1 year. From the first to the second year after deposition, a significant decrease in the activity concentration in all foodstuffs is observed due to the change from direct contam- ination to contamination caused by root uptake [29]. This change in the mecha- nism of food contamination accounts for a long-term exposure and apparent “half- life” that increases to about 6 years. For Chernobyl 137 Cs, this long-term increase in apparent half-life is even longer in some specific environments such as Scan- dinavian lakes, where fish contamination by 137 Cs still represents a significant exposure to the population [30]. A similar situation is observed in the Cumbrian region of the U.K., where sheep meat with activity levels greater than 2000 Bq/kg were still observed in 2000 [31]. It is worth noting that contamination of milk by Chernobyl-derived 137 Cs reached the same peak value (about 8 kBq/kg) observed in 1964 following nuclear weapons testing fallout in Germany. After- wards the decrease is very similar in both cases [29]. The presence of anthropogenic actinides in the environment is essentially due to the nuclear weapons testing fallout during the 1960s and 1970s, and locally to nuclear facilities. Average plutonium deposition in the Swiss lowland is about 75 Bq/m 2 , but deposition as high as 300 Bq/m 2 has been observed in the Jura Mountains [3,7]. 241 Am deposition is 0.4 times that of 239/240 Pu, indicating that fallout from nuclear weapons tests is the origin of the contamination. Because of the very low soil to plant transfer factors (less than 10 –4 ), fallout plutonium and americium are not significant contributors to internal exposure by ingestion of terrestrial foods. DK594X_book.fm Page 231 Tuesday, June 6, 2006 9:53 AM © 2007 by Taylor & Francis Group, LLC 232 Radionuclide Concentrations in Food and the Environment 8.3 PATHWAYS OF TRANSFER TO FOOD Discharge routes for radioactive waste from a nuclear site can be liquid, gaseous, and solid (as shown in Figure 8.2). Solid disposals are usually of little relevance to the food chain in the short term and thus are not considered further here. This leads to two broad categories of pathways for the movement of radionuclides into and around the food chain: aquatic and terrestrial. The aquatic pathway covers potential contamination of oceans, rivers, and lakes due to liquid discharges. The terrestrial pathway deals with potential contamination of land predominately due to gaseous discharges to the atmosphere. The aquatic pathways affect water systems both locally and at great distances. An input of radioactive material into a river can contaminate fish and shellfish directly, but that river will also drain into an ocean, where currents can carry the contamination to a wide area. These currents are slow but important pathways for areas such as the Arctic [32]. At a local level, radioactive waste discharges can have an immediate affect on the food chain. For instance, fish can incorporate 3 H in the form of 3 H 2 O into their tissue very rapidly (with a turnover time in the order of a few minutes to a few hours) and reach concentrations near that of the surrounding water [33]. Thus if discharges increase, it is likely that the activity level in fish will increase as well. Direct deposition of some radionuclides, such as 210 Po and 210 Pb, can have a significant impact on the level of these radionuclides from gaseous sources [34]. Leafy green vegetables can be directly contaminated in this manner. FIGURE 8.2 Potential radioactivity and radiation exposure pathways from a nuclear site. Atmospheric dispersion Inhalation Deposition Cloud shine Animals Crops Consumption Seafoods Resuspension Shine from contaminated land and sediments Direct shine Consumption DK594X_book.fm Page 232 Tuesday, June 6, 2006 9:53 AM © 2007 by Taylor & Francis Group, LLC Radionuclides in Foodstuffs and Food Raw Material 233 Gases, such as 14 CO 2 , can become incorporated into plant tissue at the primary level of production. At the heterotrophic level, either farm animals eat the plants and then people eat the animals, or people eat the plants directly. Terrestrial samples can also receive contamination from liquid discharges via the sea to land pathway. Sea spray can result in airborne contamination and tide- washed pastures can be contaminated directly from the waters, albeit to a lower level than from actual gaseous releases [35]. Irrigation of crops or livestock drinking river water are also ways that liquid discharges can enter the terrestrial food chain. Other pathways are investigated because of specific circumstances, such as pigeons near the Sellafield, U.K., site (discussed in Section 8.5.2). 8.3.1 F OOD G ROUPS AND R ADIONUCLIDES OF I NTEREST 8.3.1.1 Milk For terrestrial radiological monitoring programs, cow’s milk is often the predom- inant sample taken because it is readily available, consumed by a large number of people, consumed by children in relatively large quantities, and is a good indicator of radionuclides present in the environment. In the U.S., the Environ- mental Protection Agency (EPA) runs the Environmental Radiation Ambient Monitoring System program, which covers air, drinking water, precipitation, and milk [36]. Quarterly samples of milk from 42 locations (66 in 1988) are analyzed by γ spectrometry, looking for fission products such as 131 I, 140 Ba, and 137 Cs. On a less frequent schedule, samples are analyzed for 90 Sr. As part of the requirements under Article 35 of the Euratom Treaty, the European Union (EU) recommends that member states analyze 137 Cs and 90 Sr in milk from large milk processing sites [37]. Figure 8.3 shows “maximum average” levels of 90 Sr and 137 Cs in dairies sampled throughout England between 1996 and 2003. The maximum average value is the mean concentration at the farm or dairy with the highest individual result. For most foods, the maximum concentration can be selected for a dose assessment, as there is the possibility of storage of that food following harvesting, which could coincide with a peak level of activity in the food. Milk is generally not stored for long periods, so maximum averages may be used on the basis that the farm or milk production site where the highest value is found can supply milk to a consumer who consumes it in large quantities (a “high-rate” consumer). 14 C is a naturally occurring radionuclide, so some will be present in all milk samples. The U.K. uses a carbon content of 7% in milk, a background activity value of 250 Bq 14 C/kg total carbon, and a subsequent background level of 18 Bq/l 14 C for milk samples [38]. Average levels in milk samples taken from up to 17 farms per year around the nuclear reprocessing site at Sellafield, U.K., since 1991 have been shown to slightly exceed the background on a few occasions over this period. DK594X_book.fm Page 233 Tuesday, June 6, 2006 9:53 AM © 2007 by Taylor & Francis Group, LLC 234 Radionuclide Concentrations in Food and the Environment 8.3.1.2 Total Diet Samples In addition to data from milk sample analysis, the EU requires that member states report measurements for a list of recommended radionuclides in mixed diet samples to derive doses from general food consumption [37]. In the U.K., the Food Standard Agency’s Total Diet Study (TDS) is used to analyze for a range of both radioactive and nonradioactive contaminants in the general diet. The TDS samples used for radionuclide analysis were comprised of all the food groups (except beverages) in proportion of their significance in the diet. The amounts of each of the food groups eaten are derived from studies of consumption, such as the National Food Survey [39]. The use of TDS samples allows a more repre- sentative exposure estimate than analyzing all food types from an area, as people rarely obtain all their food from a local source [40]. Figure 8.4 shows the highest levels of 210 Pb and 210 Po in the U.K. TDS samples for 1995 to 2003 and the doses calculated from both naturally occurring and anthropogenic radionuclides. The figure shows that natural radionuclides domi- nate the dose, with only a fraction (no more than 13%) coming from artificial radionuclides. In 2003, 210 Po dominated, accounting for 50% of the total dose, with 210 Pb accounting for another 25% [38]. The U.S. Food and Drug Administration (FDA) has monitored levels of radionuclides in their TDS samples since 1961 [41]. Their approach has been to use a “mixed basket” and analyze individual parts of the diet separately instead FIGURE 8.3 Annual “maximum average” 137 Cs and 90 Sr levels in milk from English dairies (1996 to 2003). 0 20 40 60 80 100 120 140 160 1996 1997 1998 1999 2000 2001 2002 2003 mBq/l Cs-137 Sr-90 Year DK594X_book.fm Page 234 Tuesday, June 6, 2006 9:53 AM © 2007 by Taylor & Francis Group, LLC [...]... mBq, the lowest being the Philippines and the highest being Bangladesh Daily intakes of 238U ranged from 6.7 mBq for India up to 62.5 mBq for China 8. 3.1.6 TENORM Radionuclides As discussed in Section 8. 2.1, TENORMs are an important source of contamination for some pathways In Australia, there has been interest in levels of natural series radionuclides in foods because of the uranium mining occurring there... Martin and Ryan [51] looked at levels in traditional aboriginal foods in northern Australia The aboriginal people eat both commercial foods brought into the area and also flora and fauna from the local environment, so-called bush foods One study suggests that 40% of the total calorific intake and 81 % of the protein in the aboriginal diet comes from bush foods [53] A total of 170 species of flora and fauna... of the 137Cs activity staying in the whey (the liquid fraction) and not being present in the final cheese product The effect can also be useful at eliminating short-half-life radionuclides such as 131I In this case, the product is stored for a long period prior to human consumption and the radionuclide harmlessly decays during the storage period 8. 4.4 RECOMMENDATIONS FOR FOOD MONITORING PROGRAMS The. .. 9:53 AM 252 Radionuclide Concentrations in Food and the Environment In the U.K in 1 986 , concentrations of 131I in cow’s milk analyzed by the Central Veterinary Laboratory were found at up to 0.4 kBq/l, and radiocesium in ovine muscle was found at up to 4.2 kBq/kg in ovine meat from Cumbria and north Wales [75] The consequences of the accident have lingered for many years, especially in upland areas of... looked at the daily dietary intake of 232Th and 238U in adults living in a number of Asian countries The study covered Bangladesh, China, India, Japan, Pakistan, the Philippines, Republic of Korea, and Vietnam Together these countries represent more than half the population of the world and many of their diets are dominated by rice The study found the median daily intake of 232Th ranged between 0.6 and 14.4... 150 l/yr Scandinavian countries were greatly affected by deposition from Chernobyl Ahman and Ahman [72] reported 137Cs as high as 80 kBq/kg in reindeer meat in 1 986 , and later demonstrated a marked seasonal variation in the concentration linked with the migration of the animals between their summer range in the mountains and their winter range spent nearer the Baltic Sea Rosen et al [73] indicated an... Following the initial findings in 1997, the Environment Agency required the site to reduce its 3H discharges Prior to 1997, annual discharges of total 3H ranged from 397 to 609 TBq In May 19 98, certain tritiated methanolic wastes and 3H2O were withheld from the discharge, resulting in a reduction in total 3H discharged However, the proportion of the OBT increased to around 80 % [92] Since then the annual... important in determining discharge authorizations (both new and revised) for nuclear installations Nuclear sites throughout the world generally require prior authorization, often after extensive public consultation, by industry regulators Information generated in routine monitoring programs is invaluable in determining the effect on the environment and food of proposed emissions and routes and levels of radionuclides... 100% of the total 3H in flounders and mussels, as shown in Table 8. 4 Other species of fish and shellfish have shown similar activity levels of 3H, with high fractions of OBT [ 38, 45,77 ,89 –91] Annual averages for total 3H in © 2007 by Taylor & Francis Group, LLC DK594X_book.fm Page 2 58 Tuesday, June 6, 2006 9:53 AM 2 58 Radionuclide Concentrations in Food and the Environment sole since 19 98 have been in the. .. 0.043 0.02 0. 18 0.69 0. 68 0.59 0. 18 0. 68 0.55 2.4 0.76 0.79 6 .8 2.6 6 .8 1.3 0.61 4.9 38 38 38 38 38 38 38 38 38 38 Note: dw, dry weight; fw, fresh weight; nd, no data; ww, wet weight The Nuclear Energy Agency of the Organization on Economic Cooperation and Development is an organization whose aims are broadly “to help create sound national and international legal regimes required for the peaceful uses . Occurring Radionuclides 235 8. 3.1.4 Free Foods 236 8. 3.1.5 Freshwater Foods 237 8. 3.1.6 TENORM Radionuclides 2 38 8.3.1.7 Fish and Shellfish 239 8. 3.1 .8 Indicator Materials 239 8. 4 Monitoring Radioactivity. 226 Radionuclide Concentrations in Food and the Environment 8. 5 Introduction to Special Situations 250 8. 5.1 Chernobyl 250 8. 5.2 Sellafield and the Cumbrian Coast 252 8. 5.3 Techa River 255 8. 5.4. contami- nation for some pathways. In Australia, there has been interest in levels of natural series radionuclides in foods because of the uranium mining occurring there. A study by Martin and Ryan