Seasonal and long-term variations in 137Cs among adults from Swedish hunter families.

To study seasonal variations in 137Cs, whole-body content measurements of adults from Swedish hunter families have been performed in autumn 1997 and spring 1998. Measurements were performed in three locations, By, Harbo and Gävle, geographically close (within 100 km of each other) but with large differences in ground deposition levels. The hunter families at these three locations were previously measured in 1994. The measured persons were also asked for their frequency of intake of moose, roe-deer, reindeer, freshwater fish, mushrooms and berries. A statistically significant lower frequency of intake of mushrooms and berries in By, moose, roe deer and mushrooms in Harbo, and moose in Gävle was found in springtime compared to autumn. In one of the locations, there was a statistically significant lower average 137Cs whole-body content in spring 1998 than in autumn 1997 while in the other two locations no such effects could be seen. The 137Cs whole-body content has decreased by 37% from 1994 and to 1998 (including physical decay) correlated to an effective ecological half time of 6 years.