**6.2 Public health**

A myriad of studies are available that support the narrative linking of unconventional hydrocarbon production with a range of human health problems. Examples of these effects are cancer, mental stress, eye irritation, respiratory disease, cardiovascular disease and congenital defects [43, 44]. Whereas the potential for these diseases is undoubted, evidence-based and scientifically proven cause-and-effect relationships between unconventional production activities and community health are lacking. The constraints, in some cases, are the inaccessibility to reliable data or the biased interpretation of data or the use of non-validated protocols to generate and analyse data. It is suggested that credible studies should be based on standard epidemiological procedures [43], which properly identifies stressors and their sources, the pathways through which humans are contacted and the health impact. Potential exposures include air, soil, surface water and groundwater contamination; odours; noise; seismic events and earthquakes; increase in traffic and accident rate; and water shortage [44].
