To assess effects of fallout from Chernobyl on incidence of childhood leukaemia in Finland.
Nationwide cohort study. External exposure measured for 455 Finnish municipalities with instruments driven 19,000 km throughout the country. Values specific to municipalities corrected for shielding due to houses and fallout from A bomb testing. Internal exposure estimated from whole body measurements on a random sample of 81 children. Mean effective dose for two years after incident calculated from these measurements. Data on childhood leukaemia obtained from Finnish cancer registry and verified through hospitals treating childhood cancers.
Finland, one of the countries most heavily contaminated by the Chernobyl accident; the population was divided into fifths by exposure.
Children aged 0-14 years in 1976-92.
Standardised incidence ratio of childhood leukaemia and relative excess risk of childhood leukaemia per mSv. From incidence data of Finnish cancer registry for 1976-85, expected numbers specific to sex and age group (0-4, 5-9, and 10-14 years) were calculated for each municipality for three periods (1976-85, 1986-8, and 1989-92) and pooled as exposure fifths. Dose response was estimated as regression slope of standardised incidence ratios on mean doses for fifths for each period.
Population weighted mean effective doses for first two years after the accident were 410 microSv for the whole country and 970 microSv for the population fifth with the highest dose. In all Finland the incidence of childhood leukaemia did not increase 1976-92. The relative excess risk 1989-92 was not significantly different from zero (7% per mSv; 95% confidence interval -27% to 41%).
An important increase in childhood leukaemia can be excluded. Any effect is smaller than eight extra cases per million children per year in Finland. The results are consistent with the magnitude of effect expected.
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Comment In: BMJ. 1994 Nov 12;309(6964):12997888859
Ecological situation was examined in Eyphremovsk district of Tula region. Medico-ecologic evaluation also included the analysis of joint effects of radiation and chemical factors upon human health. The whole situation is complicated by the geographical peculiarities of the territory which is a zone of marked tectonic breaking of earth crust. The stated evaluation assumes a complex approach to solve the raised problem.
The outcome of pregnancies in six countries in Norway has been studied during 12 months prior and subsequent to the Chernobyl accident. The accident took place in a period with an annual increase of births of approximately 3%. However, the year after the accident a decrease of 0.7% was observed with particularly low numbers during February--April 1987. Concomitantly, the miscarriage fraction of all pregnancies increased by 16.3% and particularly during November 1986--January 1987. The same pattern was found when observations from Haukeland Hospital were analyzed separately. When the time of conception was taken into consideration we found that conceptions during the period May--July 1986 ended more often as miscarriages. We have no explanation of the observations. The external radiation exposure seems too small to have produced these effects. The internal radiation from food may have played a role. People may also have changed their food intake, using less vegetables, due to fear of these being polluted by radioactive fallout.
OBJECTIVE--To evaluate the risk of acute childhood leukaemia in areas of Sweden contaminated after the Chernobyl reactor accident in April 1986. DESIGN--Population based study of childhood leukaemia diagnosed during 1980-92. SETTING--Coordinates for places of residence of all 1.6 million children aged 0-15 years; aerial mapped areas of Sweden heavily contaminated after the Chernobyl accident. SUBJECTS--888 children aged 0-15 years with acute leukaemia diagnosed in Sweden during 1980-92, identified with place of birth and residence at diagnosis. MAIN OUTCOME MEASURES--Risk of leukaemia in areas contaminated after the Chernobyl accident compared with the rest of Sweden and in the same areas before the accident. RESULTS--During six and a half years of follow up after the accident the odds ratio for acute leukaemia was 0.9 (95% confidence interval 0.6 to 1.4) in highly contaminated areas (> or = 10 kBq/m2) compared with the same areas before the accident. For the subgroup acute lymphoblastic leukaemia in children aged under 5 years at diagnosis the odds ratio was 1.5 (0.8 to 2.6). For all cases diagnosed after May 1986 in highly contaminated areas compared with areas of low contamination the odds ratio was 0.9 (0.7 to 1.3). For acute lymphoblastic leukaemia in children aged under 5 years at diagnosis the odds ratio was 1.2 (0.8 to 1.9) in highly contaminated areas compared with areas of low contamination. Dose-response analysis showed no correlation between the degree of contamination and the incidence of childhood leukaemia. CONCLUSION--There has been no significant increase in the incidence of acute childhood leukaemia in areas of Sweden contaminated after the Chernobyl reactor accident.
OBJECTIVE--To assess whether the increased prevalence of trisomy 21 in West Berlin in January 1987 might have been causally related to exposure to ionising radiation as a result of the Chernobyl reactor accident or was merely a chance event. DESIGN--Analysis of monthly prevalence of trisomy 21 in West Berlin from January 1980 to December 1989. SETTING--Confines of West Berlin. RESULTS--Owing to the former "island" situation of West Berlin and its well organised health services, ascertainment of trisomy 21 was thought to be almost complete. A cluster of 12 cases occurred in January 1987 as compared with two or three expected. After exclusion of factors that might have explained the increase, including maternal age distribution, only exposure to radiation as a result of the Chernobyl reactor accident remained. In six of seven cases that could be studied cytogenetically the extra chromosome was of maternal origin, confirming that nondisjunction had occurred at about the time of conception. CONCLUSION--On the basis of two assumptions--(a) that maternal meiosis is an error prone process susceptible to exogenous factors at the time of conception; (b) that owing to the high prevalence of iodine deficiency in Berlin a large amount of iodine-131 would have been accumulated over a short period--it is concluded that the increased prevalence of trisomy 21 in West Berlin in January 1987 was causally related to a short period of exposure to ionising radiation as a result of the Chernobyl reactor accident.
Although models for calculating derived emission limits have been around for many years, the opportunity to test them against independent data sets did not arise until the Biospheric Model Validation Study (BIOMOVS) was organized in 1985. Within BIOMOVS, two scenarios tested predictions of the movement of 131I and 137Cs from air to soil, pasture, milk, and beef. One of these scenarios was a model intercomparison of a chronic release over 30 y. The second scenario, using data gathered world-wide after the Chernobyl accident, allowed predictions to be compared directly with observations. The Canadian Standards Association's Guidelines for Calculating Derived Release Limits for Radioactive Material in Airborne and Liquid Effluents for Normal Operation of Nuclear Facilities was tested in both these scenarios to see whether its predictions were suitably conservative, as they should be for a screening model. A comparison was made between results of the Canadian Standards Association's model and those of other screening models on the one hand and results of models attempting to predict best estimates on the other hand. This analysis shows that often screening models are not conservative, and thus there should be much more effort to test the models against observations.