Region continues to experience increased radioactive contamination of mushrooms

The degree of contamination varies depending on the site and the species of mushroom

Although radioactive contamination from the Chernobyl reactor disaster is now only present at low levels in most foodstuffs in Germany, some species of wild mushrooms – particularly in southern Germany – can still be highly contaminated with radioactive caesium. That is according to the latest mushroom report by the Federal Office for Radiation Protection (BfS).

The report summarises the results of a monitoring programme in which edible wild mushrooms are collected at selected locations and measurements are taken to determine their radioactive caesium (caesium-137) content.

President of the Federal Office for Radiation Protection, Dr Inge Paulini

"People buying wild mushrooms commercially needn't worry about radioactive caesium, as these mushrooms are subject to a limit value of 600 becquerels per kilogram of fresh mass," says Inge Paulini, President of the BfS.

"However, if you're collecting mushrooms yourself, it's worth taking a closer look. Especially in the Bavarian Forest or in the foothills of the Alps, elevated caesium values can appear in Hydnum repandum, Imleria badia or Cantharellus tubaeformis, for example. Although eating these mushrooms doesn't pose a health risk, you can easily avoid unnecessary exposure to radiation by leaving them in nature. There are many other types of mushrooms that only accumulate caesium-137 in small quantities."

Individual species of mushrooms show significantly higher contamination

The severity of contamination with caesium-137 varies significantly depending on the species of mushroom and from site to site. In the past three years, measurements of over 1,000 becquerels of caesium-137 per kilogram of fresh mass have been found in:

• Hydnum repandum
• Hydnum rufescens
• various species of Hygrophorus
• Imleria badia
• Cantharellus tubaeformis
• Tricholoma columbetta
• Cortinarius caperatus

In 2019, especially Hydnum repandum picked on the northern edge of the Bavarian Forest National Park showed peak values of over 4,000 becquerels of caesium-137 per kilogram of fresh mass. As part of this year's measurement campaigns, the BfS is investigating whether these unexpectedly high measurements will be confirmed again this year and what causes are responsible for them.

No health hazard associated with consumption of normal quantities

The BfS advises mushroom pickers in areas of Germany with higher levels of contamination, such as the Bavarian Forest or the foothills of the Alps, to inform themselves about the radioactive contamination of wild mushrooms. As radioactive air masses passed through these areas following the Chernobyl reactor disaster, radioactive particles were washed out of the atmosphere by rain falling in early May 1986. Wild mushrooms can readily absorb radioactive caesium from woodland soils.

Nevertheless, people should not fear negative health consequences due to this radioactivity, provided that self-collected mushrooms are eaten in normal quantities (up to about 250 grams a week). Incidentally, the following types of mushroom are among those generally considered to be harmless in terms of their radioactivity content:

• Lycoperdon pyriforme
• Agaricus silvaticus
• Infundibulicybe geotropa
• Meripilus giganteus
• Coprinus comatus.

Likewise, farmed mushrooms such as

• cultivated Pleurotus ostreatus or
• cultivated Agaricus bisporus

exhibit only very slight radioactive contamination and can be eaten without hesitation.

Annual analysis of radioactive contamination of edible wild mushrooms

The BfS has been analysing the radioactive contamination of edible wild mushrooms in southern Germany since 2005 and publishes its findings on an annual basis.

The samples are collected at typical forest sites in the Greater Munich area as well as in particularly affected areas in the Bavarian Forest and in the district of Berchtesgadener Land, which are popular destinations for mushroom pickers. The BfS works closely with mushroom experts to ensure that the analysis includes as many different species of mushrooms as possible.

At the lab, the mushroom samples are dried, ground and analysed using germanium detectors in order to determine, among other things, their caesium content.