Chernobyl originated radioactive cesium-137 in fish and mushrooms exceeds the EU levels even after 20 years


<div>The Finnish Food Safety Authority Evira and the Radiation and Nuclear Safety Authority (STUK) determined the local variations of cesium-137 and mercury content in predatory fish and mushrooms in a pilot project performed in summer 2005 in Vammala area in Finland. The project was carried out in co-operation with the environmental health authorities of the Sastamala municipal federation.</div>

Of the samples examined, in 20% of the fish and over 50% of the mushroom samples, the cesium-137 concentration exceeded the EU recommendation of 600 becquerel per kilo (Bq/kg).  Also elevated levels of mercury, over 0.4 milligrams per kilo (mg/kg), were found in 17% of the fish. The results reflect the local variations of cesium-137 levels twenty years after the Chernobyl accident in the area of heavy fallout. The cesium levels found in fish were 3–2000 Bq/kg. For mushrooms, the variations were even greater, 30–5400 Bq/kg. Large variation was seen in the concentrations of mushrooms in various growing conditions, and of fish from different types of lakes, even though the fallout level was the same. The detection limit of mercury was exceeded only in six mushroom samples.

The results confirm the need for recommendations for fish consumption. Both the cesium-137 and mercury doses to people will be decreased by reducing the consumption of large predatory fish in general and through pregnant women avoiding pike completely.  Guidance is also necessary for the consumption of mushrooms. Those who consume large amounts of mushrooms can easily reduce the intake of cesium and mercury by soaking or boiling mushrooms in plenty of water. If the mushrooms require no special treatment, it is recommended that the liquid left from frying mushrooms should be discarded and the mushrooms be lightly rinsed and strained before adding fat or oil.

The project also provided information for selling fish and mushrooms. Due to the great variations, the cesium-137 concentrations in mushrooms should be measured before selling them, with the exception of sheep polypore (Albatrellus ovinus), chanterelles (Cantharellus cibarius) and porcini (Boletus edulis). Useful lake-specific information was achieved in order to follow the EU recommendation for fish to be sold which is 600 becquerel per kilo at maximum. 

In six of the studied lakes, the mercury levels exceeded the maximum level of 0.5 mg/kg for perch. In two lakes, one pike sample exceeded the maximum level of 1 mg/kg set for pike, and in the other, the level was clearly elevated at 0.8 mg/kg.

The Finnish municipalities are classified into five different areas based on the cesium-137 fallout levels. The highest fallout levels are found in southern and central Finland. The six municipalities of Sastamala are in area 4. About half of the significantly contaminated area in southern and central Finland belongs to the highest classes of 4 and 5.

In this study a total of 79 compiled fish and 68 mushroom samples were studied. Fish samples were caught from 31 lakes and mushrooms picked from 15 different locations. The samples were provided by local fishermen and pickers. The aim of the study was to gain exact information on cesium-137 and mercury levels in fish and mushrooms for the purposes of food control and risk management and to assess the possibilities of conducting a similar study in other municipalities. The Finnish Food Safety Authority was responsible for the determination of the mercury levels and for the acquisition of the samples together with the municipal authorities of Sastamala. The Radiation and Nuclear Safety Authority and the local environmental laboratory for the area in question determined the cesium-137 concentrations.

The research results are available on Evira’s Internet pages (in Finnish):

For additional information, please contact:

A press release event for the media and the inhabitants of the Vammala area is held on 27.8.2007 at 11.00–12.30 (in the meeting room of the Vammala museum). The experts are present after the event to provide additional information.

Senior Scientific Officer Anja Hallikainen, Evira tel. 050 386 8433

Principal Advisor Riitta Hänninen, STUK tel. 040 7291986 

Senior Scientist Ritva Saxén STUK tel. 040 5489275

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