NEW STUDY. The nuclear accident in Chernobyl in 1986 led to the spread of radioactivity across Sweden and Europe. In a long-term study researchers have used new, more specific calculation methods to show the connection between radiation dose and certain types of cancer.
The study, published in the journal Environmental Epidemiology, is based on a collaboration between Uppsala University, Uppsala University Hospital, Lund University and University of Gothenburg. One of the authors is Mats Isaksson, Professor in Medical Radiation Sciences at Sahlgrenska Academy at the university of Gothenburg.
The study is a long-term follow-up covering all the inhabitants – 2.2 million – who were living in nine counties (Dalarna, Gävleborg, Jämtland, Norrbotten, Södermanland, Västerbotten, Västernorrland, Västmanland and Uppsala) in 1986.
These counties contain people with varying radiation doses from the Chernobyl fallout, caused by ingestion of contaminated food and from the surface of the soil, and who were monitored by the National Cancer Register up until 31 December 2020.
Radiation dose per individual organ
Previous follow-ups carried out in Sweden, the most recent in 2010, have shown a certain overall increase in all cancers linked to radiation from the ground.
“The big difference compared to those studies is that we have now developed and deployed a dose calculation programme to be able to calculate the radiation doses in the various organs of the body from soil and food,” says Martin Tondel, Researcher in Occupational and Environmental Medicine at the Department of Medical Sciences, Uppsala University and Uppsala University Hospital.
In the study, the researchers compared the calculated radiation doses from soil and different foods in various bodily organs to the incidence of different forms of cancer. They also adjusted for potentially influential factors such as underlying cancer incidence in the counties before the Chernobyl accident, living in urban/sparsely populated areas, education level, age and gender. Mats Isaksson explains:
“In the study, we have calculated the individual, organ-specific, radiation dose to all individuals using a model that we have worked with for a few years. The model is also the basis of a software, LARCalc, to calculate cancer risk from different exposure scenarios and can be used as a planning tool in radiation emergency preparedness”, he says.
Slightly increased incidence of cancer
The results show a slightly increased incidence of cancer in the colon, pancreas and stomach in men and a certain increase in lymphoma in women. However, the increased risks are small and cannot be translated to an individual risk, the researchers say, and they emphasise that it is important to interpret epidemiological results with caution. Martin Tondel again:
“Proven connections do not mean that we can safely say that radiation is also the cause. But studies following nuclear accidents are very important in terms of gaining more knowledge about radiation and cancer and for developing research methods. For example, we have identified that a hunting lifestyle may have played a role in our results, which means that we will be able to draw even more reliable conclusions in future studies.”
BY: UPPSALA UNIVERSITY / MARGARETA GUSTAFSSON KUBISTA