milk and reindeer meat made possible an early estimate of the 96“sr body burden in Finnish Lapps. The average content of e,, in their diet was about 30 pe/g Ca in 1960, i.e. twice that of the average Finnish diet. Assuming a discrimina~ tion coefficient of 4, the maximum 25 content of Lapp children could be estimated to about 7.5 pe/g Ca, adult Lapp in 1960, a 90 or twice the value found in Helsinki children. For the Sr bone-content of about 1 pe/g Ca could be assumed L17/- Based on bone and urine analysis, Schulert /18/ estimated Eskimos, for whom caribou is a staple in the diet, to form new bone with 12 pec Mon/g Ca, four times the Pn, content of the average of the world population of the North Temperate zone. Thus, although Mos is enriched in Lapp and Eskimo bone at a two to four times faster rate than the Northern Hemisphere average, the situation is not quite exceptional regarding his nuclide. New possibilities for direct determination of body burdens of 1 aT Cs in Lapp were opened in 1961. In spring 1961 Kurt Lidén, Head of the Department of Radiation Physics at the University of Lund, Sweden, determined at Lund the 13lo5 body burden of 3 Lapps oy whole body counting and obtained values about 40 times higher than for Swedes in general L19_/. Spurred by this alarming result, he and his associates developed in summer 1961 a semiportable whole body counter L2/ and determined with it the whole body ourden of 176 people in Swedish Lappland in.Sept.1961 L6/. One month later 180 people were counted at Inari, Finland, with the same equipment as a joint Finnish-Swedish project £9,2a1/. The latter study also included an individual dietary survey and a quantitative study of the 13!og content of the diet . With the help of a form specially made for this survey and weighed samples of most important foods and dishes each subject was interviewed about his diet. The results obtained in Sweden and Finland were very similar. In Finland the male reindcer-breeding Lapps contained on the average 245 ne ITog, 30 times the corresponding Helsinki average (6.4 ne), while females and children had an average of 122 and 51 ne 1375, respectively. Intake of og from reindeer meat (70 - 90 @), fish (8 (8-16 %) and milk (2-16 %) was found to contribute 98 to 99 % of the total dietary intake of alg, From dietary data and the measured body burden a biological half-time of 65 days for adult Lapps was calculated L9/- In Sweden the body burden of Lapps in autumn 1951 was 30 to 100 % higher, that of non-Lapps 10 to 30 % lower than in Finland fa/, mainly due to a better availability of refrigerators in the Swedish Lapp area. Prompted py the new period of nuclear weapon tests a mobile whole body counter installed in a covered truck was constructed by the laboratory of the Mt ao