Models for diffusion of innovations and Cellular Automata: an epidemiological application to pleural mesothelioma

In the city of Casale Monferrato, the largest Italian factory that produced asbestos cement goods was active from 1907 to 1985. As a consequence, asbestos fibers scattered in the surrounding area and caused an enormous number of pleural mesotheliomas. Due to the very long latency of this disease, many subjects have not exhibited its symptoms yet. The aim of this paper is to model and predict the future evolution of the number of deaths due to this disease among residents in the area around that city. The model used here is built as an aggregation of the evolution rule of a Cellular Automaton that is assumed to pass through three steps: exposure, contamination, diagnosis. In that way, forecasts of the future evolution take into account the environmental conditions that changed in time during the last century because of different levels in plant activity. The model is fitted to diagnosis data starting from the earliest until the first months of 2009. Results show that deaths will not end until 2030, and that in the next two decades, almost 500 more subjects will be diagnosed with this disease.