Obesite, diabete de type 2 et perturbateurs endocriniens

The prevalence of metabolic syndrome, obesity and type 2 diabetes has dramatically increased worldwide during the last few decades and exceeds World Health Organisation's predictions. Lifestyle factors such as decreased physical activity and energy dense diet, together with a genetic predisposition, are well-known actors in the pathophysiology of these metabolic diseases. However, there is accumulating evidence suggesting that the increased presence of endocrine disrupting chemicals (EDCs) in the environment, may also explain an important part in the incidence of metabolic syndrome, obesity and type 2 diabetes. EDCs are found in everyday products (including food, plastic bottles, metal cans, toys, cosmetics, pesticides...) and used in the manufacture of food. They interfere with the synthesis, secretion, transport, activity and/or elimination of natural hormones. Those interferences can block or mimic hormone actions and thus induce a wide range of adverse effects (especially reproductive effects and hormone-dependent cancers). In rodents, acute exposure to bisphenol A is responsible for modifications of insulin synthesis and secretion in pancreatic beta cells but also for modifications of insulin signalling in liver, skeletal muscle and adipose tissue, which both lead to insulin-resistance, a major condition in pathophysiology of metabolic syndrome, obesity and type 2 diabetes. In humans, some epidemiologic reports suggested a strong link between exposure to some persistant EDCs (as organochlorine pesticides, dioxins and polychlorinated biphenyl ethers) and type 2 diabetes and obesity, especially after acute and accidental releases of EDCs (Seveso plant explosion, Vietnam war veterans). Other cross-sectional studies among the world reported suggestive to strong association between diabetes and obesity and EDCs exposure, especially for persistant organic pollutants, which should now be considered as insulin-resistance risk factors.