An ecological analysis of leukemia incidence around the highest 137Cs concentration in Poland

Cancer has long been known to be a hazard of exposure to ionizing radiation. However, the assessment of health effects from exposure to radiation is a matter of considerable controversy. This paper presents results of a retrospective study of leukemia incidence (203-207, ICD-9) around the highest Cs-137 pollution in Poland (as an effect of the Czarnobyl disaster and/or military bomb tests). The data relating to all the registered leukemias in males and females originated from the Regional Cancer Registry in Opole. The information on Cs-137 concentration rates in Opole province was derived from the state monitoring provided by the Polish Geological Institute in Warsaw. The spatial analysis - based on the random-effects Poisson regression model - was carried out via the Markov Chain Monte Carlo (MCMC) technique (Gibbs sampling) using BUGS software. The model incorporated epidemiological data and an ecological covariate - isotope concentrations - and provided a framework for estimating the strength of a dose-response relationship. The differences in incidence levels were quantified by traditional standardized morbidity ratios (SMRs) and presented in thematic maps as well as in combined charts of distance-disease-dose relations. Additionally, to assess spatial disease clustering, a Tango test was adopted. The results of this ecological study suggest that the Cs-137 concentrations did not have any negative influence on the exposed population.