Radon in uranium mining: Still decades of cancer risk for former em-ployees

Drilling miners working underground while standing in shallow water

From the mid-1940s to 1990, 216,350 tonnes of uranium were produced in Saxony and Thuringia for the Soviet nuclear industry. The workers who mined uranium for the state-owned company Wismut were sometimes exposed to considerable amounts of the radioactive gas radon underground. As a result, many ended up dying of lung cancer – and new cases are still being reported.

According to a recent evaluation of the causes of death of uranium miners at Wismut by the Federal Office for Radiation Protection (BfS), former employees died of the consequences of radon exposure even in the third decade after mining operations ceased.

Wismut study explores effects of radon in uranium mining

Radon is formed during the radioactive decay of uranium and can also occur in other workplaces and in residential buildings (albeit in much smaller quantities than in uranium mining). The BfS has been investigating the health risk from radon since the 1990s. As part of the Wismut study, the incidence and cause of death for the almost 60,000 people employed in uranium mining operations of Wismut between 1946 and 1989 is determined every five years.

Wismut workers underground Source: Wismut GmbH

Deaths caused be radon even as late as the 2010s

At the beginning of uranium mining, Wismut workers were exposed to extremely high radon concentrations underground. In the 1960s, radon concentrations were considerably reduced and radia-tion protection improved. This also reduced the risk of developing lung cancer.

The observation period of the current evaluation covers the years 1946 to 2018. During this period, 4,329 people in the study group died of lung cancer. According to the calculations of the BfS, just under half of these deaths are due to radon. Looking only at lung cancer deaths in the period from 2010 to 2018 (roughly the third decade after the end of uranium mining) about 25% are due to radon.

If the analyses are restricted to the group of miners who began their work from 1960 onwards and were exposed to considerably less radon, about one third of the lung cancer deaths that have occurred so far can be attributed to radon. For the cases that occurred from 2010 to 2018, 19% can be attributed to radon.

BfS President Dr Inge Paulini

Radon poses a long-term health risk

"It has been proven beyond doubt that radon in the air we breathe can lead to lung cancer and that the risk increases with the level of radon concentration and the length of exposure", says BfS President Inge Paulini. With the current evaluation, the Wismut study allows scientists to more precisely quantify the connection between exposure to radon and the risk of developing lung cancer.

It is also known from the Wismut study and other studies that the risk of developing the disease can also decrease again. The further the occupational radon exposure was in the past, the lower the risk. "However, the evaluation clearly shows that the risk does not drop back to zero even after a long time. This underlines that radon is a serious health risk against which people should protect themselves. This is true not only in uranium mining but also everywhere where people are exposed to increased amounts of radon. These can be living spaces as well as workplaces", says Paulini.

Elevated radon levels in the air we breathe can occur in all indoor spaces. At www.bfs.de/radon, the BfS provides information on which regions and buildings are particularly at risk, how to detect radon at workplaces and in living spaces, and how to protect yourself against it.