Of the 18 National Priority Contaminated Sites (NPCSs) analysed in this Report, some have a single source of environmental contamination (such as fluoro-edenite in Biancavilla). In most cases, however, we are looking at multiple heterogeneous sources of contamination. In this respect, the a priori causal evaluation of the association between diseases and environmental exposures in NPCSs, based on epidemiological evidence, can help trace the health impact back to specific types of environmental exposure. There are several cases in which the project's findings have been consistent with a priori evidence: stomach cancer (both genders, excess cancer incidence) in the Fidenza NPCS; stomach cancer (women, excess mortality, cancer incidence and hospital discharges) in the Laguna di Grado e Marano NPCS; excess hospitalisation from respiratory diseases in Brescia-Caffaro, Milazzo and Terni Papigno NPCSs; excesses for non-Hodgkin lymphomas and melanoma (incidence and hospitalisation in men and women) and breast cancer (incidence and hospital discharges, women) in Brescia-Caffaro NPCS. In preorder to properly evaluate the population's health profile, we must also observe whether results remain consistent for all three health outcomes or in both genders. The first is the case of excess mortality, cancer incidence and hospital discharges for bladder cancer (men) in Porto Torres and diseases of the urinary tract in the Basso bacino del fiume Chienti NPCS). Gender consistency is observed, for instance, for all cancer in Bolzano, Porto Torres, Venice, Litorale Domizio Flegreo, Priolo, and Taranto, for all causes in Taranto, Litorale Domizio Flegreo and Trieste. The health impact in the various NPCSs needs to be considered carefully and used as a springboard for further analytical research that could confirm and explain causal links to specific environmental exposures. The observations can, however, already be considered as a basis for mandatory primary prevention measures.