Natural uranium is dangerous

Central Germany is particularly radiant Why natural radioactivity is also a danger

Central Germany shines, especially in the Ore Mountains and East Thuringia. The cause for this is usually the noble gas radon - invisible, odorless but radioactive and therefore carcinogenic. It usually arises deep in the ground when uranium decays. That is why the Geiger counters are particularly strong today in the former mining areas of the SDAG Wismut. There, the Soviet-German mining company mined uranium for decades, which was also used to build the first atomic bomb in the Soviet Union.

Strong radioactivity in granite mountains

The radiation dose to which people in Germany are exposed on average is around 2.1 millisieverts per year (mSv / a). The researchers distinguish between two types of naturally occurring radioactivity: On the one hand, there is cosmic radiation from space, which is weakened by the atmosphere on its way to the ground and is usually only a problem for frequent flyers. The second source are radioactive substances that occur in the earth's mantle, in this country mainly the elements uranium and thorium.

The main deposits of the two metals are the soils of low mountain ranges with granite rock. In Germany, in addition to the Fichtel and Ore Mountains, these are the Bavarian Forest and the Black Forest. In the decay process of uranium and thorium, among other things, radon-222 is produced, which emits alpha radiation. It escapes from the ground through cracks and crevices.

Known since the 16th century: Schneeberger disease

The radioactive gas becomes a problem above all when it seeps through leaky cellar walls in residential buildings and collects there in the air we breathe. Residents usually breathe in radon without even realizing it. Researchers estimate that the radiation emitted by the gas is responsible for five to ten percent of all lung cancers. This makes it the second most common cause of this cancer after smoking.

The phenomenon is not new: in the Saxon Ore Mountains, doctors described Schneeberger disease as early as the 16th century, which primarily affected the lungs of miners. How high the concentration is in the area is shown by measurements in which up to 100,000 Becquerel and more were found in the soil. For comparison: the EU reference value is 300 Becquerel. If the radiation in the indoor air of a building is higher, authorities urgently recommend remedial measures to reduce pollution. From December 2018, a corresponding law will come into force that makes new regulations for protection against radiation.

The Becquerel unit is used to measure the number of decaying atomic nuclei in one cubic meter of air, i.e. a theoretical cube with an edge length of one meter each in width, length and height.

The Sievert unit is used to measure the risk of radiation exposure. The amount of radioactivity, known as the radiation dose, is related to the likelihood of it causing cancer in humans. Since the dose of a Sievert represents a very high value, millisievert (mSv) or microsievert (µSv) are usually used.

Natural radiation increases the risk of cancer

A study by the Munich Environmental Institute shows how dangerous naturally occurring radioactivity, for example radon escaping from the ground, can be. Scientists there investigated whether there was a statistical connection in Bavaria between cancer deaths and infant mortality on the one hand and natural radioactivity on the other.

Bavaria lends itself to such an investigation: In the Free State there is a strong gradient between areas such as the Bavarian Forest with a lot of natural radiation and areas with little radioactivity, such as the Allgäu in the south-west of the country. The result was surprisingly clear: even when the researchers excluded other influences, a significant connection was visible. With an increase in radiation exposure of one millisievert per year, the cancer rate grew by ten percent, and infant mortality by as much as 20 percent.

Radon: Between healing power and health risk

However, radioactive radon does not only have negative effects. Rheumatism sufferers report that bathing in water containing radon leads to pain relief. Health resorts such as Bad Schlema, where uranium was mined in GDR times, are now relying on radon baths again, which attract numerous guests.

In order to be able to better estimate health risks, the Saxon authorities have made very detailed, area-wide measurements of the radon potential in the soil air and created maps from them. How high the load on individual properties is, however, cannot be read from the maps. Even in an area with generally high levels of radon exposure, the radiation can be very low in individual cases. The authorities therefore recommend that you measure yourself in each apartment. With the right remediation, the pollution can also be significantly reduced in areas with a lot of radon.