EXTERNAL AND INTERNAL IRRADIATION OF SWEDISH REINDEER BREEDERS 1950-1970

The 137Cs body burden of Swedish reindeer-breeding Lapps, which was at a maximum in early summer, 1965, has been studied since 1961. Our investigation of the seasonal variation in 1965 and 1966 shows that the annual 137Cs dose to Lapps can be estimated by only one observation a year of the body burden. In June, 1967 a survey was made in two Lapp communities with a portable sensitive gamma-radiation dosimeter. In addition to indoor and outdoor measurements, the shielding effect of the snow cover was also studied. The total external natural irradiation amounted to 67 mrad/yr; the external irradiation from fallout during the period 1950–70 is calculated to be about 55 mrad, an average increase of 4% over the natural external irradiation. The 55Fe body burden of Swedish Lapps has been estimated by analyses of blood samples. The dose from other natural and artificial radioactivity, especially 40K, 210Po and 90Sr, has been calculated. The RBE of 210Po alpha-particles is discussed. The average absorbed dose in the body from natural irradiation amounts to 95 mrad/yr. The irradiation from fallout, dominated by the contribution of 700 mrad from 137Cs, reaches 760 mrad during the twenty-year period. Comparisons are made with the irradiation of other Swedes and with other arctic groups with similar food habits. © 1969 Health Physics Society.