The Finnish Radiation and Nuclear Safety Authority (Stuk) says that fallout from the Chernobyl nuclear accident can still be detected in Finnish foods, but that it accounts for less than one percent of the average annual radiation dose for people in Finland.
The city of Helsinki's urban environment division said on Monday that two samples of funnel chanterelle (or yellow leg) mushrooms it tested contained levels of radioactive caesium that exceeded the recommended maximum.
According to EU guidelines, food products offered for sale should not contain more than 600 becquerels per kilo (Bq/kg) of caesium-137. Mushrooms picked in Pälkäne in Pirkanmaa, south-central Finland had a reading of nearly 1,000 Bq/kg. Meanwhile those picked in Hyvinkää, some 60 km from the capital, contained 1,300 Bq/kg. Wild produce from around the country is widely sold at marketplaces in the capital.
Most caesium disappears in cooking
On Wednesday, Stuk said that consumers can eat such mushrooms without worry despite their caesium content. The agency estimates that the annual dose of radiation from caesium in mushrooms is less than 0.01 millisievert (mSv) for the average consumer in Finland – compared with the average dose from all radiation sources, which is some 3.2 mSv annually.
Stuk points out that caesium levels in mushrooms is reduced by rinsing and cooking them. This can remove as much as 80 percent of their caesium content. Drying mushrooms does not affect radiation levels, though.
The Chernobyl nuclear power plant accident occurred in April 1986 in Ukraine, which was then part of the USSR.
Winds carried caesium fallout from the plant to Finland, with the heaviest concentrations in the southern regions of Pirkanmaa, Häme and Kymenlaakso. Wild game, lake fish and forest berries also still contain tiny amounts of caesium-137 from Chernobyl.
Fallout from the accident accounts for less than one percent of the average Finn's annual exposure to radiation – about half of which comes from air-borne radon inside buildings, says Stuk.