This is the second paper on the Project Manfredonia Environment and Health launched on February 2015 and based on a participatory approach. After a serious industrial accident on 1976 with release of several tons of arsenic, the management of environmental issues produced distrust and suspicion towards institutions and these feelings are still alive in the civil society. The Project is therefore based on a strong public engagement on each phase of the epidemiological investigation. In this article we report the second phase in which all the stakeholders consider all possible analysis results and the implications in terms of public health action plans. This step is relevant in order to acknowledge the limitation of the epidemiologic study due to uncertainties and assure transparency to the decision processes.