A 25-year follow-up of malignancies in Sweden after the Chernobyl nuclear power accident in 1986

Introduction:

The 1986 nuclear power accident at the Chernobyl nuclear power plant resulted in the release of 5,300 PBq of radioactive material (excluding noble gases). Five percent of the total caesium-137 released from the Chernobyl reactor was estimated to be deposited in Sweden giving a possible maximum dose to the population up to 10 mSv. Apart from the induction of thyroid cancer among children in the former Soviet Union there has been a scientific debate whether the release of radionuclides from the Chernobyl accident has caused any radiogenic malignancies in Europe. The aim was to compare the incidence of cancer in areas with low compared to areas with high deposition of cesium-137 in Sweden.

Methods:

Malignancies from 1980 to 2010 were retrieved from the National Cancer Registry. Cumulative exposure data for each individual were based on recurrent aerial measurements of caesium-137 deposited on the ground (kBq/m2). The incidence rate of radiation exposure was estimated via poisson regression with adjustment for sex and age at exposure.

Results:

Among the total population (n=2575403) there were 64719 cases of malignancies registered by the Swedish national cancer registry. The cumulative exposure value ranged from 0-604 kBq/m2*years. The RR for the interquartile range increase of cumulative exposure (31-173 kBq/m2*years) was 1.02 (C.I. 1.01-1.03).

Discussion

Risk assessment from low level exposure to ionizing radiation (<100 mSv) has a great value for both occupational and environmental acceptable doses. Present study shows a small increased occurrence of total malignancies in the total population related to the deposition of caesium-137. Further analyses will be made both on specific malignancies such as thyroid cancer and leukaemia and occupations with possible higher exposure, such as farmers and reindeer herders.