Study of occupational and environmental exposure to asbestos through linkage methods and spatial analysis

INTRODUCTION The identification and monitoring of cancers caused by occupational or environmental exposure to asbestos is an important aspect of public health The first aim of the study was to identify patients with a cancer different from malignant mesothelioma (MM), who worked in firm with at least possible occupational asbestos exposure [BRIC]. The second aim was to assess the spatial variation of MM risk in the area of Casale Monferrato and to detect clustering associated to the secondary sources of asbestos [LATENT]. METHODS For the first project [BRIC], we considered the registries of MM from seven Italian Regions, while the other cancer cases (OCM) were available only for two. As ReNaM and OCM could not be merged directly due the absence of a linkage key, different linkage methods were implemented. For the second project [LATENT], we used data from a population-based case–control study conducted in Casale Monferrato between 2001 and 2006. Demographic and occupational data along with residential information were recorded. The spatial variation in disease risk was mapped and adjusted logistic models were applied. RESULTS In BRIC, we included 4134 cases of MM recorded in ReNaM, corresponding to 12801 occupational records. The linkage procedure allowed to identify 2606 firms with asbestos exposure. Of 35010 cases included in the OCM system, 6546 (18.7%) worked in these firms. One hundred ninety-six cases and 322 controls were included in the analyses of LATENT project. The plot showed a well-defined peak of MM incidence near the asbestos cement factory when large bandwidths were used. However, changing parameters, several peaks of increased risk were reported. A constant trend of decreasing Odds Ratio with increasing distance was observed, with estimates of 10.9 and 10.48 for 0-5 km and 5-10 km, respectively (reference >15 km). CONCLUSION The project has allowed to deepen the study of the effect of two types of asbestos exposure: occupational and environmental.