Objective: to estimate the spatial distribution of risk, in order to assess its correlation to environmental pollution exposure around the large production facilities located in the Taranto area, and to identify high risk areas not previously reported.
Setting: Italy, Taranto province (581,508 inhabitants).
Design: incidence data in 29 municipalities of the Taranto province were extracted from the Jonico Salentino Cancer Registry (RTJS) for the following cancer sites: lung (ICDX C33-C34); pleura, pleuric mesothelioma (ICDX C45.0); bladder, malignancies only (ICDX C67); brain (ICDX C70-72); non-Hodgkin lymphoma (ICDX C82-85, C96); leukaemia (ICDX C91-5). Age standardized incidence rates for the whole province were computed. High-level risk areas were classified using a Poisson model, computing area-specific p-values associated to the null hypothesis of no increased risk (i.e. relative risk equal to 1). A hierarchical spatial Bayesian model was estimated to strengthen results: specifically two additional variance components, accounting for relative risk spatial autocorrelation and excess heterogeneity respectively, were considered in the model specification. Bayesian mapping of disease incidence allows for the drawing of regularized (smoothed) maps. To adjust for the effect of socio-economic deprivation, a five-variable index was introduced into the model as an ecological covariate.
Results: an increased risk of lung, pleura and bladder cancer was observed among male residents in the city of Taranto (respectively: SIR 1.24, p-value < 0.01; SIR: 2.21, p-value < 0.01; SIR 1.28, p-value < 0.01). For non-Hodgkin lymphoma, a significant value was observed in the city of Taranto for males (SIR 1.46, p-value < 0.01), as well as in the neighbouring area of Pulsano for females (SIR 3.88, p-value < 0.01). An unexpected increased risk of brain cancer was found in both sexe risk (especially among males) of lung, pleura and bladder cancer is likely related to the chemical pollutants and asbestos, due to the presence of many industries and shipyards in the city of Taranto.