Food and household water

Wild berries and mushrooms

Wild berries and mushrooms

Similar to other outdoor plants, forest vegetation is exposed to radioactive substances in the soil and air. Both naturally occurring radioactive materials and those being spread by fallout accumulate in plants and, consequently, game animals. These substances are transferred into people through forest foods, causing an internal radiation dose.

Most of the cesium-137 in forest products results from the Chernobyl nuclear power plant accident. The regions that were most heavily hit by the cesium-137 fallout from Chernobyl are Pirkanmaa, Häme and Kymenlaakso, while Eastern and Northern Finland and the south-western coast received less fallout.

Wild berries contain less cesium-137 than game, reindeer meat and wild mushrooms. However, the cesium concentration in cloudberries picked in the heaviest fallout area may occasionally exceed the 600 Bq/kg maximum level recommended by the EU. In some places, certain mushroom species have rather high concentrations of cesium originating from the Chernobyl fallout.

In addition, wild berries and mushrooms contain naturally occurring radioactive materials, such as uranium, radium, polonium, lead and potassium. The level of naturally occurring radioactive materials in wild berries is low. Some mushroom species, such as some boletuses, accumulate more polonium-210 than others.

Polonium-210 and lead-210, which occur naturally in Northern Finland, expose users of wild berries and mushrooms to a higher radiation dose than artificial cesium.

Concentrations of naturally occurring radioactive materials (Bq/kg fresh weight) in wild berries and mushrooms

Product   Bq/kg  
  U-234 U-238 Pb-210 Po-210 Ra-226 Ra-228

Wild berries







Wild mushrooms







Cesium-137 concentrations in wild mushrooms by species

The transfer of cesium-137 to mushrooms varies depending on the species. Commercial mushrooms have been divided into three groups in accordance with the efficiency of cesium transfer. Group 1 includes mushrooms that accumulate the lowest amount of cesium, and mushrooms in group 3 accumulate the highest amount.

  1. False morel (Gyromitra esculenta), Forest Lamb (Albatrellus ovinus), honey fungi (Armillaria), true morels (Morchella), Leccinum species, Slippery Jack (Suillus luteus), chanterelle (Cantharellus cibarius), matsutake (Tricholoma matsutake)
  2. Brittlegills (Russula), funnel chanterelles (Chantarellus lutescens, Chantarellus tubaeformis) and horn of plenty (Craterellus cornucopioides)
  3. Milk-caps (Lactarius), hedgehog mushroom (Hydnum repandum), terracotta hedgehog (Hydnum rufescens), velvet bolete (Suillus variegatus), gypsy mushroom (Cortinarius caperatus) and arched woodwax (Hygrophorus camarophyllus)

The cesium-137 concentration limit for food imported to the EU is 600 becquerels per kilogram (Bq/kg). According to the European Commission recommendation (2003/274/Euratom), this should be applied to the trade of wild food products in the EU region. In regions that were exposed to a heavy fallout, this limit may be exceeded in the mushroom groups 2 and 3. The cesium concentration in arched woodwax is commonly over 600 Bq/kg also in fallout areas with a relatively low cesium concentration in the soil.

Leccinum species
Funnel chanterelle
Hydnum species
Boletus species
Gypsy mushroom

The average cesium-137 concentrations in mushrooms have varied in the range of about 0 to 2000 Bq/kg. The lowest concentrations have occurred in fallout region 1 and the highest in fallout regions 4–5.Cesium-137 in mushrooms (Bq/kg fresh weight), averages and ranges of variation in different fallout regions (‘1’ indicates the lowest and ‘5’ the highest cesium concentration in soil).  The 600 Bq/kg limit specified in the EU recommendation is indicated in red in the figure.

The amount of radioactive cesium (cesium-137) in mushrooms can be reduced during cooking, using common mushroom treatment methods. When mushrooms are soaked or boiled in water, most of the radioactive cesium in them is released into the water.


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