The integration of current data sources is now a practice widely used in epidemiology, especially in the environmental field. To better describe the health profile of populations residing in proximity to areas characterized by a "strong environmental pressure", the combined use of multiple indicators (i.e., mortality, hospitalization, cancer incidence) is recommended. To choose an indicator is complex, as indicators should be contextualized and they need to be related to the several issues involved in the studied pathology. This chapter explores the general considerations that are to be addressed both at the time of the study design, during the selection of outcomes and of the proper data sources, and at the time of the discussion of the results, when different and complementary data are compared. A special focus is devoted to the case of mesothelioma.