Comparison of the post-Chernobyl 137Cs contamination of mushrooms from eastern Europe, Sweden, and North America.

A comparison was made of 134Cs and 137Cs contamination in fungi from eastern Europe and eastern North America. Mean activities of 25 Ukrainian, 6 Swedish, and 10 North American collections were 4,660, 9,750, and 205 Bq/kg (dry weight), respectively. Additional measurements were made on samples from the Moscow, southern Belarus, and Yugoslavia/Bulgaria regions. Activity values were found to vary by several orders of magnitude within all geographic areas, even for the same mushroom species. Significantly higher specific activities were observed in mycorrhizal species than in saprophytic and parasitic fungi. Unfortunately, many of the European mycorrhizal species considered as prized edibles contained unacceptably high levels of 137Cs (> 1,000 Bq/kg [dry weight]) and should be used sparingly as food. By contrast, no mushrooms collected in Ontario or northern Michigan exceeded 1,000 Bq of 137Cs per kg (dry weight). The excessive 137Cs contamination was evident in mushrooms from areas that had substantial fallout from the 1986 accident in reactor 4 at the Chernobyl nuclear power station. However, observations suggest that about 20% of the 137Cs in eastern Europe (Moscow area, Belarus, and Ukraine) is of non-Chernobyl origin.