The radiological situation in Germany in 1986

Soil contamination with caesium-137 in 1986 (Bq/m²). Since then, a little over one half of caesium-137 has decayed. The map well reflects the current situation (2022), when multiplying the contamination levels by 0.44.

At the end of April/beginning of May 1986, the radioactive air masses from the Chornobyl reactor accident arrived in Germany. Because there was heavy local precipitation in Southern Germany at this time, Southern Germany was significantly more polluted than Northern Germany:

• Locally, up to 100,000 becquerels of radioactive caesium-137 per square metre – and sometimes more – were deposited in the Bavarian Forest and south of the Danube.
• In the North German Plain, on the other hand, the activity deposition of this radionuclide rarely exceeded 4,000 becquerels per square metre.

The activity deposits of radioactive caesium-134 were about half of those of caesium-137.

The radioactive substances were also deposited in forests, fields, and meadows. The direct deposition of radioactive substances on pastures and a few crops ready for harvest quickly led to high levels of radioactive iodine-131 in cow's milk and leafy vegetables (e.g. spinach) ready for harvest in Southern Germany..

Radionuclides relevant for Germany in 1986

Because of its short half-life of about 8 days, the radioactive iodine-131 had already largely decayed after only a few weeks. The contamination with radioactive iodine-131 came from an amount of less than 1 gram that had been deposited over what was then the Federal Republic of Germany.

Radioactive caesium (caesium-137 and caesium-134) entered plant-based foodstuffs and feed through the leaves after direct deposition on the aerial parts of the plant. According to the Gesellschaft für Strahlen- und Umweltforschung (GSF; now HMGU, Helmholtz Zentrum München – German Research Centre for Environmental Health), about 230 g of radioactive caesium-137 had been deposited over the Federal Republic of Germany.

In the long term, radioactive caesium is essentially taken up from the soil via the roots. Because radioactive caesium is strongly bound to certain clay minerals in the mineral soils of many arable fields, only negligible amounts reach the plants via the roots. Agricultural crops that were not sown or planted until after the Chernobyl reactor accident were therefore contaminated with only a few becquerels of radioactive caesium per kilogramme in the summer of 1986.

Protective measures

At the beginning of May 1986, the Commission on Radiation Protection recommended that only fresh milk with less than 500 becquerels of radioactive iodine-131 per litre be released for direct consumption. Some federal states applied much stricter standards and recommended, for example, that fresh milk with concentrations of radioactive iodine-131 above 20 becquerels per litre not be consumed.

The dairy farmers therefore disposed of milk from cows that had been fed on fresh pasture. They also ploughed contaminated outdoor vegetables under so that they could no longer be sold. The population avoided possibly contaminated foodstuffs such as seasonal outdoor vegetables.

Current state of affairs: The radiological situation in Germany today

Of the radioactive substances released in the Chornobyl accident, only the long-lived caesium-137 is still relevant for the radiation to which humans and the environment are exposed (radiation exposure) in Germany and Central Europe. Because of its half-life of about 30 years, caesium-137 has decayed by slightly more than half from 1986 until today.

The radiation from caesium-137 to which people are exposed in Germany and Central Europe (e.g. through exposure from the outside or inhalation) can therefore be classified as low. The contamination of agriculturally produced foodstuffs with caesium-137, which is relevant for the uptake of the radionuclide with food, is also only minimal; only foodstuffs from the forest can still have increased levels of radioactive caesium-137.

Radioactive iodine-131 released from the reactor in Chornobyl in 1986 no longer plays a role because of its short half-life of 8 days; it has completely decayed.

Radioactive caesium in agricultural foodstuffs in Germany

Today, only low levels caesium-137 activity are found in domestically produced crops.

In Germany, there are no longer any radiologically relevant levels of radioactivity in agriculturally produced foodstuffs such as cereals, meat, or milk.

In mineral soil layers, such as those found on arable and pasture land, radioactive caesium is fixed by certain clay minerals contained in the soil and can thus be taken up only to a minimal extent by soil organisms and plant roots. Thus, more than 30 years after the accident, only low levels of caesium-137 activity can still be found in the crops produced in Germany. The content of caesium-137 in agricultural products from domestic production is now only a few becquerels per kilogram and below.

The result is that in Germany, less than 100 becquerels of caesium-137 per person and year are ingested on average with foodstuffs from agricultural production.

Current measurement results for agricultural products from domestic production (2020)

Measurement results from the Integrated Measuring and Information System for the Surveillance of Environmental Radioactivity (IMIS) for agricultural products from domestic production in 2021 (as of 2 March 2022): Specific caesium-137 activity in becquerels per kilogram fresh mass or becquerels per litre

product	number of samples	minimum value	maximum value	mean value
milk (collection milk)	804	< 0,01	0,5	0,07
meat (beef, veal, pork, poultry)	1.103	< 0,04	12,9	0,2
leafy vegetables (outdoor cultivation)	692	< 0,02	2,4	0,1
fresh vegetables without leafy greens (outdoor cultivation)	639	< 0,02	0,4	0,08
potatoes	236	< 0,04	0,4	0,08
cereals	666	< 0,02	2,2	0,08

Limits for foodstuffs from trade in Germany

For commercially available foodstuffs in Germany, the limits for radiocaesium are as follows:

• 370 becquerels per kilogram for milk, milk products, and foodstuffs for infants and toddlers
• 600 becquerels per kilogram for all other foodstuffs.

Foodstuffs from German forests

Significantly elevated caesium-137 activities can still be measured in wild mushrooms and game, especially wild boar.

The situation for forest foodstuffs is quite different from the agricultural sector. Forest soils are characterised by organic layers on top of the mineral soils. In these layers, which are formed from decomposing litter and rich in soil organisms, radioactive caesium is readily available and is quickly taken up by soil organisms, fungi, and plants. It thus migrates only slowly into the mineral soil layers, where it can be fixed by certain clay minerals. The content of radioactive caesium in forest products therefore usually decreases only slowly.

Even today, more than three decades after the Chornobyl accident, significantly elevated caesium-137 activities can still be measured in foodstuffs from the forest such as edible mushrooms and game. A locally high fluctuation of the caesium-137 content is characteristic for wild mushrooms and game, especially wild boar.

Foodstuffs from the forests in the parts of Germany that were particularly affected by the Chornobyl fallout in 1986 – in particular the Bavarian Forest and the areas south of the Danube – have a higher level of contamination. There, forest products such as some edible mushroom species and wild boar meat sometimes still have caesium-137 levels of well over 100 becquerels per kilogram. In wild boar, well over 1,000 becquerels per kilogram, and in some cases even more than 10,000 becquerels per kilogram, are possible. In other regions (e.g. Northern Germany), the activity levels are much lower because of the lower deposition of radioactive caesium.

If you want to minimise your individual exposure to radiation, you should limit – or even eliminate – the consumption of wild mushrooms that you have picked yourself and game that you have shot yourself (especially wild boar) from the Bavarian Forest and other highly contaminated areas in Southern Germany.

Wood from Southern Germany, which was more severely affected by the accident in Chernobyl, can have caesium-137 activities of up to several 100 becquerels per kilogram.

More forest products from Germany

Wood from southern Germany, which was more severely affected by the reactor accident in Chornobyl, can have caesium-137 activities of up to several 100 becquerels per kilogram.

In the case of wood products such as furniture or parquet flooring, the radiation to which people are exposed is only minimal – as is the case for firewood burnt in an open fireplace or wood pellets used in boilers in private households. However, because caesium-137 remains mainly in the ash, this should not be used to fertilise vegetable beds in private gardens just to remain on the safe side.

As long as no large quantities of wood are burnt in biomass power plants in Germany, monitoring of the radioactivity content of the wood ash (or the proper disposal thereof) is not important from a radiation protection point of view.