Background: According to radiation risk estimates uniformly adopted by various official organizations, exposure to Chernobyl fallout is unlikely to have caused any measurable health risk in central Europe.
Methods: A re-evaluation of ECLIS (European Childhood Leukaemia and Lymphoma Incidence Study), a large IARC-coordinated project in the context of various published studies.
Results: ECLIS revealed a slightly higher leukaemia incidence in the most contaminated European regions, and an increasing trend with estimated cumulative excess radiation dose. The excess corresponds to 20 cases of childhood leukaemia in the study area up to 1991. More recent evidence from Greece and Germany indicates significantly higher risks in the cohort of children in utero at the time of the initial fallout. In Greece, a positive trend was observed over three regions of increasing average fallout contamination.
Conclusion: Chernobyl fallout could well have caused a small, but significant excess of childhood leukaemia cases in Europe. The etiologic mechanism might include an induction of chromosome aberrations in early pregnancy. Increased risks in the birth cohort exposed in utero correspond to 11 excess cases in Greece and another 11.4 excess cases in Germany. Exposure misclassification and underascertainment of incident cases render post-Chernobyl risk estimates probably too low. If indeed Chernobyl fallout has caused childhood leukaemia cases in Europe, we would also expect an increased incidence for other childhood cancers and excess malignancies in adults as well as non-malignant diseases of all ages. Neither of these endpoints has as yet been systematically studied.