Radiation dose from wild berries and mushrooms

Cesium concentrations in berries are clearly lower than in mushrooms. Cloudberries and cranberries may have slightly higher concentrations compared with other wild berries. Within the same area, differences in habitat cause variation in the concentrations in berries and mushrooms.

In bilberries and lingonberries, the average cesium-137 concentration is approximately 40 becquerels per kilogram. This means that the average consumer who eats eight kilograms of wild berries per year receives a radiation dose of approximately 0.004 millisieverts per year. This is 0.1 per cent of the average radiation dose of 3.2 millisieverts per year that each Finn receives from all sources combined.  Even heavy consumers who pick their berries from the heaviest fallout areas receive a relatively low dose, approximately 0.1 millisieverts per year.

With regard to the radiation dose, the most significant naturally occurring radioactive materials are lead-210 and polonium-210. The dose caused by them to a person who eats wild berries is approximately 0.005 millisieverts per year or less. The corresponding dose to a person who eats mushrooms is less than 0.003 millisieverts per year. The consumption of natural produce per year is estimated at 1.5 kg for mushrooms and 10 kg for berries.

Radioactive substances are no reason to leave bilberries in the forest. The radiation dose remains low even for heavy users of berries.

Even though cesium concentrations in mushrooms can be high and exceed the recommended maximum limit, they can be safely used for food. Normal consumption does not increase the annual radiation dose much. The radiation dose received by the average consumer from cesium in mushrooms is less than 0.01 millisieverts per year. The average radiation dose received by Finns from all sources combined is approximately 3.2 millisieverts per year. The level of the radiation dose received from mushrooms depends not only on the fallout level of the mushroom picking area, the consumed amount and the mushroom species, but also on the treatment of mushrooms when cooking them for food. For example, soaking and boiling mushrooms can reduce the amount of cesium in them by as much as 80 per cent.

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