Mushrooms 2025 Campaign

The Radiation and Nuclear Safety Authority (STUK) is organizing a campaign from early July to the end of November to measure edible mushrooms. During the campaign, you can send edible mushrooms collected in Finland during the current year to STUK, following the given instructions.

The aim of the campaign is to examine the concentrations of radioactive cesium (Cs-137) in mushrooms and how these concentrations vary by region and mushroom species. Results will be released in stages depending on the number of samples. Results will be available by April 2026 at the latest.

Most of the radioactive cesium present in Finnish nature originates from the Chernobyl nuclear power plant accident in 1986, which will have occurred 40 years ago in April 2026. STUK’s nationwide environmental monitoring program has tracked the presence of radioactivity from the Chernobyl fallout in the environment ever since the accident. Small amounts of radionuclides from the fallout are still present in Finnish nature.

Mushrooms Are Nutritious

Edible mushrooms growing in Finnish forests are nature’s own superfood – delicious, nutritious, and a sustainable choice for your plate. They are rich in beneficial nutrients and enhance the diet.

Cesium levels in mushrooms have decreased over the past 40 years. The recommended limit for cesium is 600 becquerels per kilogram. Although occasional exceedances are found in mushrooms, they contribute well under one percent of the average annual radiation dose received by Finns. Therefore, it is safe to collect and enjoy mushrooms. Cesium can be reduced by processing the mushrooms, although processing is not necessary for radiation safety.

More information on processing methods can be found on the Finnish Food Authority’s website. (in Finnish)

How to Participate – Instructions for Sending Mushrooms

You can participate in the campaign by submitting a dried or fresh mushroom sample to STUK. The mushroom sample must be collected in 2025 and sent according to the instructions below no later than November 2025.

We will send the measurement result of your mushroom sample by email if you provide your email address. The results will be completed in stages during the winter and published on this page.

If we receive more samples than we can measure, we will stop accepting new samples and notify about it on this page.

For more information about the Mushrooms 2025 campaign, please contact [email protected].

Thank you for your participation!

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Pick edible mushrooms as you would for normal household use and clean them of debris and soil. Include both cap and stem. Each sample should contain about one liter of fresh mushrooms.
Slice the mushrooms for the sample and dry them using a dehydrator or oven.
If possible, weigh the mushrooms with a kitchen scale before and after drying.
Pack the dried mushrooms for shipping in a resealable bag (such as a Minigrip or similar). If you are sending multiple species, keep them separate and pack each in its own bag.

If drying is not possible, you may send fresh mushrooms. In this case, collect the sample over the weekend and mail it on Monday so that it arrives within the working week. There is no such urgency with dried samples.

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5. Print out the sample information form and fill in the requested details. If you are sending multiple species, fill out a separate form for each one. If you are unable to print the form, you can write the same information on a separate sheet of paper.

6. On the sample information form or separate sheet, provide at minimum the mushroom species (as specifically as possible), the date of collection, and the municipality where it was collected.

Print out instructions and sample information form to fill in (pdf)

7. If possible, also include GPS coordinates of the collection site (you can get these via Google Maps on your phone) and mushroom weights (fresh and dried).

8. Remember to include this information with every sample.

9. If you wish to receive the measurement results by email, remember to provide your name and email address with the sample information.

Names and coordinates won't be published, and the samples won't be returned to senders. Contaminated samples will not be tested.

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10. Mail the note and the mushroom sample (at your own expense) to:

Mushrooms 2025/MIT
Radiation and Nuclear Safety Authority
Jokiniemenkuja 1,
01370 Vantaa, Finland

Note: If sending via Matkahuolto, choose Business parcel (jakopaketti) to ensure delivery directly to the Radiation and Nuclear Safety Authority.

11. You may also deliver the packed sample directly to STUK’s front desk within two days or by the next working day after collection, between 8:00 and 16:00. Address: Jokiniemenkatu 28, Vantaa.