Radioactivity of Foodstuffs in Finland in 1987-1988
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-n STUK-A78 JUNE 1991 Radioactivity of foodstuffs in Finland in 1987-1988 Supplement 4 to the Annual Reports STUK-A74 and STUK-A89 Aino Rantavaara •w r*i^^$^Jpi*&&>i SÄTEH.YTURVAKESKUS StrciKakerhohrentralen STUK-A78 JUNE 1991 Radioactivity of foodstuffs in Finland in 1987-1988 Supplement 4 to the Annual Reports STUK-A74 and STUK-A89 Aino Rantavaara FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY P.O. Box 268, SF-00101 HELSINKI Finland Tel. +358 0 70821 ISBN 951-47-5259-7 ISSN 0781-1705 The Finnish Government Printing Centre Helsinki 1991 Sold by: The Finnish Government Printing Centre P.O. Box 516 SF-00101 HELSINKI Tel. +358 0 56601 FINNISH CENTRE FOR RADIATION STUK-A7N AND NUCLEAR SAFETY KiNTAVAUU A. Radioactivity offocxlstuffs in Finland in 1987 - 19SS. Supplement 4 to the Annual Reports STUK-A74 and STUK-AS9, Helsinki 1991. ISBN 951-47-5259-7 ISSN 0781-1705 Key words Radioactive fallout, radioccsium, '"Sr, 1J,I, foodstuffs, dietary intake ABSTRACT Radioccsium and radiostrontium in foodstuffs of agricultural origin were surveyed in Finland in 1987 - 1988. The nationwide survey was a continuation to an earlier foodstuff monitoring programme, which was extended both areally and by the types of foodstuffs after the Chernobyl accident in 1986. The purpose of the programme was to give information for dose assessment and on temporal changes and regional differences in the contents of fallout radionuclides in foodstuffs. Most 1J7Cs and all mCs found in foodstuffs originated in the Chernobyl fallout, whereas the bulk of *Sr came from atmospheric nuclear weapons tests. The nationwide production-weighted annual mean contents of ^Sr, lwCs and "7Cs in different foodstuffs were calculated. Regional differences in radioactive faliout accumulated in soil were taken into account in the calculation. For the main groups of domestic unprocessed foodstuffs consumed in Finland, the nationwide mean contents of radionuclides as Bq kg"1 fresh weight were: Foodstuff ^Sr wCs !"Cs 1987 1988 1987 1988 1987 1988 Milk 0.15 0.13 7,4 2.8 17 8.1 Meat 0.02 0.01 17 5.9 43 21 Egg» 0.04 0.02 0.2 0.1 0.5 0,2 Cereals 0.4 0.4 0.5 0.5 1.2 1.7 Vegetables 0.2 0.3 0.9 0.3 2.5 1.1 Fruit and berries 0.3 0.2 1.4 0.4 3.4 15 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A78 Average annual consumption rates for adults were used to calculate the mean intakes received via different groups of foodstuffs. Total intakes also include information on radionuclides in wild produce. No spontaneous changes in diet caused by the Chernobyl accident were taken into account in intake estimates, given as Bq a"1 per person (preliminary estimates within parentheses): Year *Sr 134Cs I37Cs 1987 Agricultural and garden produce 100 3100 7600 Fish and other wild produce (10) 2400 6600 1988 Agrigt'ltural and garden produce 1(X) 1100 3400 Fish and other wild produce (10) (1400) (49',. tt Traces of 131I were detected in milk from northern Finland in August 1987 resulting from a venting of an underground nuclear test explosion in Novaya Zcmlya. No other short or medium half-life nuclides were found in foodstuffs in 1987-1988. 4 FINNISH CENTRE FOR RADIATION STUK-A78 AND NUCLEAR SAFETY CONTENTS Page ABSTRACT 3 CONTENTS 5 1 INTRODUCTION 6 2 MATERIAL AND METHODS 2.1 Sampling 7 2.2 Sample analysis 9 2.3 Data treatment 10 3 RESULTS AND DISCUSSION 3.1 Radiocesium in foodstuffs 14 3.2 ^Sr in foodstuffs 16 3.3 w,l in milk 16 3.4 Dietary intakes 17 ACKNOWLEDGEMENTS 19 REFERENCES 20 FIGURES 22 TABLES 29 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A78 1 INTRODUCTION In 1987 and 1988 the nationwide radioactivity survey of foodstuffs at the Finnish Centre for Radiation and Nuclear Safety continued much in the same way as during the second half of 1986.u The sampling and analysis programme was adjusted annually to meet the requirements of dose assessment and of the follow-up of temporal changes in the radionuclide contents of foodstuffs. This report contains results for both *Sr and radiocesium in agricultural products and vegetables and fruit. Wild berries, mushrooms and game meat were also surveyed in 1987-1988, but arc outside the scope of this report, and the findings will be published later. Information on foodstuffs of wild origin, namely preliminary analyses of data for wild terrestrial foodstuffs, and reports on the monitoring of the aquatic environment has also been used for the dietary assessment.1'5 A special pathway monitored in 1987 was contaminated horticultural peat used as a growing medium for greenhouse vegetables. An extensive survey on peat w;.;:; started in late autumn 1986 to check the need for protective measures before the planting of cucumber, tomato and lettuce. Decontamination of peat by watering, or change of growing medium was recommended for commercial gardens where peat might have caused the 137Cs contents in vegetables to exceed 100 Bq kg"1. More tomato and cucumber samples were also taken for this study to comply with the recommendations given at the beginning of 1987. The results of the survey on horticultural peat will be published in another paper. Experiments on the reduction of radiocesium by cooking or by special treatments of foodstuffs were carried out in 1987 as a part of the monitoring programme. Foodstuffs contaminated by radioactive fallout were used as test material. The results have been published elsewhere. * The long-lived radionuclides found in foodstuffs in 1987 - 1988 originated in both the fallout from 'he Chernobyl accident and the earlier atmospheric nuclear test explosions. The radioactivity data for foodstuffs since 1960, presented in the figures of Chapter 3, have been published in the report series SFL-A, STL-A and STUK- A of the Centre. Very small amounts of 1311 were detected in milk in August 1987. These observations followed the detection of radio-iodine in ground-level a'r in northern Finland and the neighbouring countries after the venting of an underground nuclear test explosion in Novaya Zcmlya.7 6 FINNISH CENTRE FOR RADIATION STUK-A78 AND NUCLEAR SAFETY 2 MATERIAL AND METHODS 2.1 Sampling Sampling was organized by the Centre in co-operation with a number of organisa tions engaged in the control, production or distribution of foodstuffs. As of the end of 1986. sampling was gradually changed into a long-term follow-up programme of the long-lived radionuclides from the Chernobyl fallout. The principle of taking samples at an early stage after production, when identification of origin is possible, was maintained. Both the distribution of production and the contributions of different types of foodstuffs to the intake of radionuclides were considered in sampling. Areal samples were taken of milk, beef, pork, eggs and of four types of cereals: wheat, rye, barley and oats. Vegetables included samples of potato, leafy and root vegetables grown outdoors, and fruit and leafy vegetables and herbs from green houses. Fruit samples were taken from apples, strawberries and bush berries. The samples were farm-specific, collected either directly at a farm or commercial garden or at a storage for distribution. Milk, beef, pork and eggs were sampled at regular intervals throughout the year. Cereals, vegetables and frait samples were collected during or after the harvest each year. The numbers of vegetable and fruit samples decreased most after 1986. No essential changes were needed in the numbers of areal samples of milk, meat and cereals. The complementary samples from individual municipalities were, however, minimized. About 900 foodstuff samples were sent to the laboratory for this study both in 1987 and 1988. Some samples consisted of several subsamplcs, and, especially for radiochemical analyses, samples were combined further in the laboratory. (Table I). More was learnt of the distribution of the Chernobyl fallout in Finland during the study, The information supported all parts of the surveillance programme by giving means for reliable weighing procedures for nationwide assessment (Fig. 1)." Covering the entire production areas by sampling was not necessary. Special emphasis was placed on obtaining represented vc samples of different plant growing conditions and different production practices. All provinces were generally included in the sampling of foodstuffs, regardless of the degree of contamination by the Chernobyl fallout. In choosing farm-specific vegetable and fruit samples, some bias towards the municipalities most affected by the fallout was allowed in order to have detectable radionuclide contents. A weighing procedure based on the distribution of fallout and on the production 7 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A78 statistics of foodstuffs ensured that the nationwide mean contents were not disturbed by the bias in sampling. Milk. Milk distributed for daily consumption was sampled at the dairy after it had been received from the farm. Samples were taken on a weekly basis on two successive days and they were sent to the laboratory cither weekly or monthly. The sampling of milk continued as in 1986 from the areas ID, HA, IIIB, IV, VI, IX, X, XI. XII, XIII and XIV. New milk sampling areas in 1987 and thereafter were 1IIC and XV. In 1987 the sampling of milk ceased from areas IC, 1IIA and VIIIB, and one year later also from area IV. Sampling area IE was temporarily excluded from the programme for the year 1987. (Figs. 2a, 2b). Milk powder. Monthly milk powder samples were collected systematically in proportion to the quantities of dried milk. Sampling continued as in 1986 from areas I, II, HI and VII. In 1988 dry milk was temporarily sampled from areas VIIIA and XIIIA (Figs.