J-/S80C02S «^TU£v9—£2 STUK-A62 June 1987 RADIOACTIVITY OF GAME MEAT IN FINLAND AFTER THE CHERNOBYL ACCIDENT IN 1986 Supplement 7 to Annua! Report STUK A55 Airo R.mMvii.ir;). T'mt! Nytjrr-r K.t.ulo r-jytJr»• r•; ,iin! T,ip,ifi' f-K v ••••<-!• STV K - A - - 6 2. STUK-A62 June 1987 RADIOACTIVITY OF GAME MEAT IN FINLAND AFTER THE CHERNOBYL ACCIDENT IN 1986 Supplement 7 to Annual Report STUK-A55 Aino Rantavaara, Tuire Nygr6n*, Kaarlo Nygren* and Tapani Hyvönen * Finnish Game and Fisheries Research Institute Ahvenjärvi Game Research Station SF - 82950 Kuikkalampi Finnish Centre for Radiation and Nuclear Safety P.O.Box 268, SF-00101 HELSINKI FINLAND ISBN 951-47-0493-2 ISSN 0781-1705 VAPK Kampin VALTIMO Helsinki 1988 3 ABSTRACT Radioactive substances in game meat were studied in summer and early autumn 1986 by the Finnish Centre for Radiation and Nuclear Safety in cooperation with the Finnish Game and Fisheries Research Institute. The concentrations of radioactive cesium and other gamma-emitting nuclides were determined on meat of moose8 and other cervids and also on small game in various parts of the country before or in the beginning of the hunting season. The most important radionuclides found in the samples were 134Cs and 137Cs. In addition to these, 131I was detected in the first moose meat samples in the spring, and 110"Ag in a part of the waterfowl samples. None of them was significant as far as the dietary intake of radionuclides is concerned. The transfer of fallout radiocesium to game meat was most efficient in the case of the arctic hare and inland waterfowl; terrestrial game birds and the brown hare belonged to the same category as moose. The nationwide mean contents of radiocesium in different types of game meat, weighted for areal distribution of both the annual game bag and deposited radiocesium, are given below together a The scientific and Finnish names of the species are given in Table I. 4 with the mean dietary intakes via game meat: Type of game Content (Bq kg "; ) Intake (Bq per person) meat i3*Cs I37Cs "« Cs "7 Cs Moose 80 170 77 194 Cervids other than moose 190 400 11 28 Hares 200 420 14 35 Waterfowl 150 310 12 25 Terrestrial game birds 50 130 2 5 Intake in 1986 47 106 Intake in 1987 69 180 Total intake via game meat 1986.'1987 120 290 The contribution of cervids to the total dietary intake of radiocesium via game meat was 3/4, which was slightly less than their contribution to the annual game bag. On the basis of the preliminary results of this study it was concluded in autumn 1986 that there was no need to restrict hunting in the year 1986/1987. The radiocesium found in the .neet of terrestrial game animals did not necessitate any recommendations on their use. As regards the meat of waterfowl caught in the main inland fallout area, it was recommended not to eat more than 20 kg per person. 5 CONTENTS ABSTRACT CONTENTS INTRODUCTION 7 MATERIAL AND METHODS 2.1 Sampling 9 2.2 R-rdionuclide analysis 10 2.3 Data treatment 2.3.1 Estimation of transfer factors 11 2.3.2 Estimation of areal radiocesium contents 12 2.3.3 Estimation of dietary intake 13 RESULTS 3.1 Radionuclide contents of game meat 15 3.2 Transfer of fallout radiocesium to game meat 16 3.3 Dietary intake of radionuclides via game meat 16 DISCUSSION 4.1 Radionuclide contents of game meat 18 4.2 Transfer of radiocesium to game meat 4.2.1 Game meat in general 19 4.2.2 Moose and other cervids 21 4.2.3 Small game 22 6 4.3 Dietary intake of radiocesium via game meat 23 5 ACKNOWLEDGEMENTS 25 REFERENCES 26 FIGURES 29 TABLES 40 7 1 INTRODUCTION The survey of radioactive substances in game meat in 1986 was a part of the fairly comprehensive monitoring of foodstuffs carried out by the Finnish Centre for Radiation and Nuclear Safety (STUK). The objective was to determine the degree of contamination of game meat by the radioactive fallout of spring 1936, in order to assess the importance of game meat as a dietary source of radiocesium. Information on the environmental transfer of radiocesium through natural food chains was also obtained. The Finnish Game and Fisheries Research Institute was responsible for the organization of sampling and gave biological expertise at different stages of the study. Moose*, also called elk, is by far the most important game animal in Finland, with a winter population of 78 000 - 85 000 individuals in 1985 - 1987, and almost 45 000 - 55 000 animals culled annually.8 Moose was also the species for which the present sampling was most representative. The next most important species in the group of cervids, to which it belongs, is the white-tailed deer. About 86 % of the annual game bag of 9 x 106 kg in Finland came from this group of animals. Hares and waterfowl contributed most to the annual small-game bag in 1986/1987. Altogether, game meat added about three per cent to the average 66 kg per capita consumption of meat produced by animal husbandry. Hunting is to some extent concentrated in southern and central Finland,3 where the deposition of radioactive substances was higher than in the northern and easternmost parts of the country. When the mean deposition of 13 7 Cs was weighted for the areai game bag, the nationwide mean, 14 kBq 137Cs per square meter, exceeded the surface area weighted mean for Finland by a factor of I.3.1 The radioactive fallout of spring 1986 arrived in Finland at a time when a gradual, for some terrestrial species radical, change • The scientific and Finnish names of the species are given in Table I, 8 in forage was beginning, in connection with the snow melt. At this time, too, moose were migrating to summer pastures. The maximum intake of radionuclides by game animals occurred immediately after the arrival of fallout, via forage plants exposed directly to deposition of radioactive substances. The intake of radio-nuclides by terrestrial game animals decreased in summer, when fresh grass and leaves of trees not exposed directly to fallout became available. The transfer of radiocesium from fallout to meat is more efficient in natural food-chains than in animal husbandry. This was evident in a previous study on radiocesium in moose meat in Finland. The study from 1979, made when annual deposition of 137Cs was low, revealed large ranges of 137Cs contents in areas with the same or comparable accumulated deposition. Some sources of the variation were identified, as for example forage plants with high mineral contents, growing on wetlands, and mushrooms in autumn.10 The same factors as earlier affected the radiocesium contents of game meat in 1986, additional pathways being direct deposition on forage plants in the spring and contamination of drinking water by fallout. The probably efficient transfer of radiocesium from the new fallout to game meat and the large ranges that could be expected in the radiocesium contents prompted us to assess the contamination before the hunting season of 1986. At the beginning of autumn 1986, the only important nuclides were 134 Cs and 137Cs. 9 2 MATERIAL AND METHODS 2.1 Sampling When the sampling programme wa» planned, areal differences in the deposited amounts of radiocesium were not known in detail (Fig. 1). To fulfil the requirement of advance information to consumers of game meat, nationwide sampling seemed necessary for at least the most important game animal, moose. Samples were taken of altogether 16 species, of which 15 belong to those hunted in Finland. Only a few species were chosen as the main representatives of groups of birds living in similar environments or using the same type of food. The numbers of samples were roughly proportioned to accord with the contributions of different species or groups to the annual game bag: Group or species Number of samples Moose 298 Cervids other than moose 34 Hares 23 Waterfowl 79 Terrestrial birds 15 The majority of the samples were taken before the hunting season. By order of the Ministry of Agriculture and Forestry, the police districts provided samples of moose and white-tailed deer killed or Injured in traffic accidents. The Game and Fisheries Research Institute conducted experimental hunts, which supplemented the moose samples and provided most of the samples of small game. The Northern Research Station of STUK delivered moose samples from Lapland. Many private persons and local Game Management Associations also assisted in sampling. 10 The samples for the study were collected from the whole country (Figs. 2 - 7), except for small game, which In Lapland was studied by the Northern Research Station of STUK.13 The sampling locations of moose represented 163 municipalities. The samples of moose meat were usually taken between the shoulder blades or from the neck. About half a kilogram of chilled moose meat was sent by express delivery to the laboratory, with records of the location and date of sampling, and the sex and age group (adult/calf) of the animal. Samples of small game were often sent as whole animals. These were cleaned and a sample was taken of the breast muscle In the case of birds, and the hind leg In the case of hares. 2.2 Radionuclide analysis All the samples were analysed for gamma-emitting fallout nuclides, most of them as individual samples. In a few cases two or more samples from nearby locations were combined. The total number of gammaspectrometric analyses of moose meat was 274 and that of other game 124.