RISK OF ACUTE CHILDHOOD LEUKEMIA IN SWEDEN AFTER THE CHERNOBYL REACTOR ACCIDENT

Objective-To evaluate the risk of acute childhood leukaemia in areas o f Sweden contaminated after the Chernobyl reactor accident in April 19 86. Design-Population based study of childhood leukaemia diagnosed dur ing 1980-92.Setting-Coordinates for places of residence of all 1.6 mil lion children aged 0-15 years; aerial mapped areas of Sweden heavily c ontaminated after the Chernobyl accident. Subjects-888 children aged 0 -15 years with acute leukaemia diagnosed in Sweden during 1980-92, ide ntified with place of birth and residence at diagnosis. Main outcome m easures-Risk of leukaemia in areas contaminated after the Chernobyl ac cident compared with the rest of Sweden and in the same areas before t he accident. Results-During six and a half years of follow up after th e accident the odds ratio for acute leukaemia was 0.9 (95% confidence interval 0.6 to 1.4) in highly contaminated areas (greater than or equ al to 10 kBq/m(2)) compared with the same areas before the accident. F or 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 a reas of low contamination the odds ratio was 0.9 (0.7 to 1.3). For acu te lymphblastic leukaemia in children aged under 5 years at diagnosis the odds ratio was 1.2 (0.8 to 1.9) in highly contaminated areas compa red with areas of low contamination. Dose-response analysis showed no correlation between the degree of contamination and the incidence of c hildhood leukaemia. Conclusion-There has been no significant increase in the incidence of acute childhood leukaemia in areas of Sweden conta minated after the Chernobyl reactor accident.