[SENTIERI Project: discussion and conclusions]

The SENTIERI Project represents the first comprehensive analysis of the health impact of residence in National Priority Contaminated Sites (NPCSs). For the first time, it considers three distinct health outcomes: mortality (2003-2010), cancer incidence (1996- 2005) and hospital discharges (2005-2010). The Report includes a commentary explaining methodology and approach, as well as remarks on the causal association between environmental exposures and investigated health outcomes based on the a priori assessments of the epidemiological evidence; the main implications for public health and scientific research priorities are also presented. The approach put forward by SENTIERI was among those sanctioned by the World Health Organization to conduct an initial description of the health status of residents of contaminated sites. Results relating to individual diseases that can be traced back to a single agent, such as asbestiform fibres, can be easily analysed. The Biancavilla NPCS (where the fluoro-edenite asbestiform fibre was found) displays excesses of pleural mesothelioma and its proxy, malignant pleural tumours, as does Priolo, where asbestos coexists with other pollutants. Increased risk was also recorded in NPCSs adjacent to the coast hosting harbour areas (such as Trieste, Taranto and Venice) or comprising industrial areas specialising in the production of chemicals (Laguna di Grado e Marano, Priolo and Venezia) and steel (Taranto, Terni, Trieste). Increases of pathologies, such as cancer and respiratory diseases, connected to more than one agent, in industrial sites with multiple and diverse sources of exposures, prove harder to interpret. There are also more complex cases in which results do not appear consistent in the three databases or by gender (such as lung cancer in Venice, where mortality and hospital discharges have only increased among women). In order to adequately examine these we must consider factors such as the appropriateness of the health outcome showing the increase, considering latency and the length of the observation period. Of further interest are results relating to diseases of the urinary tract such as kidney failure in the NPCSs of Basso bacino del fiume Chienti, Taranto, Milazzo and Priolo. Overall, the results discussed above are consistent with the previous findings pertaining to mortality for 1995-2002. The present analysis also introduces a new element - the study of cancer incidence and hospital discharges - which can tell us a great deal about diseases with high survival rates or non lethal ones. The first is the case of thyroid cancer, which presents increases in both databases and for both genders in a number of NPCSs (Brescia-Caffaro, Laghi di Mantova, Milazzo, Sassuolo- Scandiano and Taranto). The study of cancer incidence and hospital discharges also revealed cancer excesses for melanoma, breast cancer and non Hodgkin lymphoma in Brescia-Caffaro NPCS where PCBs (Polychlorinated biphenyl) are the site's main pollutant. PCBs, according to the 2013 evaluation of the International Agency for Research on Cancer, are ascertained human carcinogens for melanoma and probable carcinogens for breast cancer and non-Hodgkin lymphoma. The results pertaining to cancer incidence in the 17 NPCSs can also be presented using rankings by area or disease analyzed by a multivariate hierarchical Bayesian model. These rankings reveal an overlapping of credibility intervals, such that it is not possible to speak of a limited number of cancer sites or of certain NPCSs as being particularly affected. Every NPCS, therefore, must be considered individually and ordering them by ranking of cancer incidence wouldn't be appropriate. Data collected concerning some of the NPCSs in the context of the SENTIERI Project is so conclusive that remediation measures can immediately be put in place. This is the case in the Biancavilla and Brescia-Caffaro NPCSs. A similar conclusion can be drawn for complex locations such as Taranto, where, based on the results of SENTIERI Projects and the whole available information, we can safely conclude that exposure to environmental agents played an important role, allowing us to set in place 'Integrated evaluation of environmental and health impact procedures'. SENTIERI approach does not allow definitive causal assessments. However, as stated above, these results do provide a topic for further study without getting in the way of initiatives promoting urgent environmental remediation.