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Increase of regional total cancer incidence in North Sweden due to the Chernobyl accident?
Linköping University, Department of Clinical and Experimental Medicine, Occupational and Environmental Medicine . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Occupational and Environmental Medicine Centre.
Department of Oncology, Örebro University Hospital, Örebro, Sweden.
Department of Health Policy, Västernorrland County Council, Härnösand, Sweden.
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2004 (English)In: Journal of epidemiology and community health, ISSN 0143-005X, Vol. 58, no 12, 1011-1016 p.Article in journal (Refereed) Published
Abstract [en]

Study objective: Is there any epidemiologically visible influence on the cancer incidence after the Chernobyl fallout in Sweden?

Design: A cohort study was focused on the fallout of caesium-137 in relation to cancer incidence 1988–1996.

Setting: In northern Sweden, affected by the Chernobyl accident in 1986, 450 parishes were categorised by caesium-137 deposition: <3 (reference), 3–29, 30–39, 40–59, 60–79, and 80–120 kiloBecquerel/m2.

Participants: All people 0–60 years living in these parishes in 1986 to 1987 were identified and enrolled in a cohort of 1 143 182 persons. In the follow up 22 409 incident cancer cases were retrieved in 1988–1996. A further analysis focused on the secular trend.

Main results: Taking age and population density as confounding factors, and lung cancer incidence in 1988–1996 and total cancer incidence in 1986–1987 by municipality as proxy confounders for smoking and time trends, respectively, the adjusted relative risks for the deposition categories were 1.00 (reference <3 kiloBecquerel/m2), 1.05, 1.03, 1.08, 1.10, and 1.21. The excess relative risk was 0.11 per 100 kiloBecquerel/m2 (95% CI 0.03 to 0.20). Considering the secular trend, directly age standardised cancer incidence rate differences per 100 000 person years between 1988 to 1996 and the reference period 1986–1987, were 30.3 (indicating a time trend in the reference category), 36.8, 42.0, 45.8, 50.1, and 56.4. No clear excess occurred for leukaemia or thyroid cancer.

Conclusions: Unless attributable to chance or remaining uncontrolled confounding, a slight exposure related increase in total cancer incidence has occurred in northern Sweden after the Chernobyl accident.

Place, publisher, year, edition, pages
2004. Vol. 58, no 12, 1011-1016 p.
Keyword [en]
ionising radiation, epidemiology, environment
National Category
Medical and Health Sciences
URN: urn:nbn:se:liu:diva-14506DOI: 10.1136/jech.2003.017988OAI: diva2:23608
Available from: 2007-05-15 Created: 2007-05-15 Last updated: 2009-08-21
In thesis
1. Malignancies in Sweden after the Chernobyl accident in 1986
Open this publication in new window or tab >>Malignancies in Sweden after the Chernobyl accident in 1986
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

On 26 April 1986 an accident occurred in the Chernobyl nuclear power plant resulting in the release of large amount of radionuclides. Almost five percent of the total released caesium-137 was deposited in Sweden. The incidence of malignancies in the most affected counties in Sweden was investigated in three epidemiological studies.

In the first study the incidence of malignancies in children and adolescents was studied for the period 1978-1992. The parishes and their inhabitants were classified according to the ground deposition of caesium-137 on an analogue map provided be the Swedish Radiological Protection Authority. A continuous increase of brain tumour incidence observed during the time of the study had no clear relationship to the Chernobyl fallout. A somewhat decreased relative risk of ALL was observed in areas with increased deposition. Other malignancies showed no changes in incidence over time or with regard to the exposure of caesium-137. In study II and III we enlarged the study base by including adults. We improved the methodology by defining a cohort of subjects who lived in the same parish from 31 December 1985 to 31 December 1987. The inhabitants from seven counties were included. Parishes were classified the same way as in study I. Due to the large number of individuals six exposure categories could be created; <3, 3–29, 30–39, 40–59, 60–79, and 80–120 kBq caesium-137/m2. The inhabitants of the 117 non-affected parishes (<3 kBq/m2) served as reference. During the 1988-1996 followup, 22,409 malignancies were recorded. The MH-IRR in the fully adjusted model was 1.00 (reference), 1.05, 1.03, 1.08, 1.10 and 1.21, respectively. ERR was 0.11 per 100 kBq/m2 (95% CL 0.03;0.20). A more advanced method was used in Study III by ignoring the exposure classification for parishes, and instead matching the dwelling coordinate to a digital map of deposition of casesium-137. In spite of a more valid exposure classification the risk estimates were similar in study II and III. Also, the ERR during the longer follow-up of 1988-1999 was almost identical, 0.10 per 100 kBq/m2 (95% CL 0.00;0.23). The strongest dose-response relationship was seen in the first four years (1988-1991). No obvious excess for leukaemia or thyroid cancer was recognised in either study II or III. The estimated number of exposure related cases was calculated to 849 in study II and 1,278 in study III. Our interpretation is that we have shown an increased incidence of total malignancies with dose-response relationship for caesium-137, only a few years after the Chernobyl accident. In study IV we compared the two different ways of classifying the exposure in study II and III. Out of the 450 parishes 111 got a different classification. The similar risk estimates in study II and III could probably be explained by relatively homogenous exposure in the parishes making the intra-parish difference less influential, especially when included in categories. In study V we examined the urinary excretion of 8-OHdG in Belarussian children from areas with high and low fallout of caesium-137, respectively. We found significantly lower urinary 8-OHdG levels in children from rural contaminated areas compared to urban uncontaminated areas, suggesting an urban, rather than a radiation related, risk factor.

Using the Hill criteria for causality there is support for a causal inference between the fallout of caesium-137 from the Chernobyl accident and the increased incidence in total malignancies in Northern Sweden.

Place, publisher, year, edition, pages
Institutionen för molekylär och klinisk medicin, 2007. 57 p.
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1001
Epidemiology, Environmental, Chernobyl, ionising radiation, geographical information systems GIS, 8-OHdG, Malignancies, Low dose, Dose-response, Latency, Causalty
National Category
Public Health, Global Health, Social Medicine and Epidemiology
urn:nbn:se:liu:diva-8886 (URN)978-91-85715-17-6 (ISBN)
Public defence
2007-06-04, Aulan, Hälsans Hus, Campus US, Linköpings Universitet, Linköping, 09:00 (English)
Available from: 2007-05-15 Created: 2007-05-15 Last updated: 2009-08-22

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