Cancer incidence in northern Sweden before and after the Chernobyl nuclear power plant accident
2014 (English)In: Radiation and Environmental Biophysics, ISSN 0301-634X, E-ISSN 1432-2099, Vol. 53, no 3, 495-504 p.Article in journal (Refereed) Published
Sweden received about 5 % of the total release of Cs-137 from the Chernobyl nuclear power plant accident in 1986. The distribution of the fallout mainly affected northern Sweden, where some parts of the population could have received an estimated annual effective dose of 1-2 mSv per year. It is disputed whether an increased incidence of cancer can be detected in epidemiological studies after the Chernobyl nuclear power plant accident outside the former Union of Soviet Socialist Republics. In the present paper, a possible exposure-response pattern between deposition of Cs-137 and cancer incidence after the Chernobyl nuclear power plant accident was investigated in the nine northernmost counties of Sweden (2.2 million inhabitants in 1986). The activity of Cs-137 from the fallout maps at 1986 was used as a proxy for the received dose of ionizing radiation. Diagnoses of cancer (ICD-7 code 140-209) from 1980 to 2009 were received from the Swedish Cancer Registry (273,222 cases). Age-adjusted incidence rate ratios, stratified by gender, were calculated with Poisson regression in two closed cohorts of the population in the nine counties 1980 and 1986, respectively. The follow-up periods were 1980-1985 and 1986-2009, respectively. The average surface-weighted deposition of Cs-137 at three geographical levels; county (n = 9), municipality (n = 95) and parish level (n = 612) was applied for the two cohorts to study the pre- and the post-Chernobyl periods separately. To analyze time trends, the age-standardized total cancer incidence was calculated for the general Swedish population and the population in the nine counties. Joinpoint regression was used to compare the average annual percent change in the general population and the study population within each gender. No obvious exposure-response pattern was seen in the age-adjusted total cancer incidence rate ratios. A spurious association between fallout and cancer incidence was present, where areas with the lowest incidence of cancer before the accident coincidentally had the lowest fallout of Cs-137. Increasing the geographical resolution of exposure from nine county averages to 612 parish averages resulted in a two to three times higher value of variance in the regression model. There was a secular trend with an increase in age-standardized incidence of cancer in both genders from 1980 to 2009, but significant only in females. This trend was stronger and statistically significant for both genders in the general Swedish population compared to the nine counties. In conclusion, using both high quality cancer registry data and high resolution exposure maps of Cs-137 deposition, it was not possible to distinguish an effect of Cs-137 on cancer incidence after the Chernobyl nuclear power plant accident in Sweden.
Place, publisher, year, edition, pages
2014. Vol. 53, no 3, 495-504 p.
Cancer, Cesium-137, Chernobyl, Ecological study, Environment, Epidemiology, Ionizing radiation, Nuclear accident, Radiation, Sweden
Environmental Health and Occupational Health
IdentifiersURN: urn:nbn:se:uu:diva-231289DOI: 10.1007/s00411-014-0545-6ISI: 000339898300003PubMedID: 24811728OAI: oai:DiVA.org:uu-231289DiVA: diva2:744529