CS-137 IN THE POPULATION OF NORTHERN SWEDEN

Whole-body content of Cs-137 has been measured in both 1991 and 1992 i n the population of northern Sweden, with a special interest taken in the Saami population. Measurements were performed in three areas with different deposition levels, using a whole-body counter installed in a mobile container. In this way the expected high refusal frequency cau sed by the large distances in this part of Sweden could be reduced. Tw o groups of individuals were randomly chosen, one group representing t he total population of the area, and the other the members of the Saam i communities. In order to investigate whether 15 year old students co uld be regarded as a representative sample of the total population, me asurements of whole-body content and urine samples were performed on s chool classes in two of the areas. The average whole-body content of C s-137 in the general population varied between 1.1 and 2.0 kBq, and fo r the Saami population between 3.4 and 25 kBq, dependent on deposition level. The ratios between whole-body content and deposition found in these measurements were consistent with earlier studies of Cs-137 from Chernobyl in other areas of Sweden; however, previously published dat a based on measurements of Cs-137 from nuclear weapons fallout, shows a 20-40 times higher ratio. This may be an effect of the different beh aviour in the environment of caesium from Chernobyl compared with caes ium from nuclear weapons fallout, or a result of effective countermeas ures.