Contribution of Bayesian Networks to Environmental Health Issues, Application to Etang de Berre
Authors: PEREZ Sandra , Labaume Catherine German , Mathiot Sebastien , Goix Sylvaine , Chamaret Philippe 
Published: August 2021

Abstract
Background: The aim of this study is to examine in detail the potential links between proven pathologies in the population and the atmospheric pollution to which this population is exposed, in an industrial context (Etang de Berre) and an abundant cocktail of pollutants, in connection with the diversity of emitting sources within that space (petrochemical industry, steel industry, refining, energy production, cement works, road, sea and air transport).Methods: A total of 178 variables of various natures (health, environmental and socio-economic) on a fine territorial scale (infracommunal) have been mobilised and simultaneously integrated within a Bayesian model based on artificial intelligence. Various unsupervised and supervised algorithms, and also sensitivity analyses provide the means to discover the links between these variables and the inhabitants’ living space.Results: By mobilising a high number of variables, broken up on a fine territorial scale, and by resorting to an appropriate tool to report on existing links between these variables, we were able to bring to the fore a number of relations between exposure and proven pathologies. For example, between cadmium and diabetes in the over 65 year-olds, or between vanadium and respiratory diseases. Threshold effects have also been revealed, notably for SO 2 which appears from a very low exposure threshold (6µg/m 3 ), therefore far below standard, which is set at 50µg/m 3 . It is also the case with hydrofluoric acid (HF), the effect of which is already felt from the 0.0028 μg/m 3 threshold. Also, exposure to cadmium in its particle phase, for an exposure between 0.214 and 0.250 μg/m 3 , disrupts insulin metabolism in the over 65. Finally, as soon as Benzo[k]fluoranthene (particle phase) exceeds the 0.672 μg/m 3 threshold, it results in a higher number of hospital stays for respiratory diseases in the 15-65 age group. A vulnerability differentiated according to age groups also appeared. Comorbidities known in literature have been found (respiratory and heart diseases). Also found was the influence of socio-economy on some pathologies (single-parent families and those without qualification at 15). Finally, diffuse PCBs pollution has been observed in the study area.Conclusion: The study has brought forward differentiated health profiles between the various IRISes 1 constituting the Pays de Martigues territory, and this should lead to the deployment of health services better suited to the needs of the population from a prevention perspective, and even to promote consultations with some specialists. For example, with a cardiologist, in those IRISes where the number of unqualified 15 year-olds is significant, since a relation has been found at that level, a relation most probably due to more difficult living and/or working conditions for these people. Likewise, prevention and social support measures should be taken to the benefit of single-parent families. At the same time, companies should go ahead with the desulfurization process of their installations, and even reduce their emissions concerning some noxious pollutants.Trial registration: Decision DE-2017-413 authorising the Métropole d’Aix Marseille Provence to carry out the processing of personal health data for a retrospective and local environmental health study titled “Air-Health study in the Pays de Martigues territory.” (Authorisation application No. 917120)