Role of Environmental Chemicals in Obesity: A Systematic Review on the Current Evidence

The purpose of this paper is to systematically review the experimental and human studies on obesogenic chemicals and their mechanisms of action to provide a comprehensive view on the multifactorial aspects of obesity. The literatures were searched in available databases. The relevant papers were selected in three phases. After quality assessment, two reviewers extracted the data while another checked their extracted data. In this review, we summarized information regarding environmental chemicals that can be associated with obesity. Most evidence comes from experimental and laboratory studies; however a growing number of human studies also support the role of obesogenic chemicals. The current evidence proposes that the systemic responses to exposure to environmental factors could potentially increase the risk of excess weight. The effects of exposure to these chemicals are of crucial importance during developmental phases of life, when preprogramming for an adipogenic outcome may occur. By considering the adverse transgenerational effects of obesogen chemicals on human health, the global obesity epidemic should be considered as a multifactorial complex disorder necessitating the emphasis of public health interventions for environmental protection. 1. Introduction Obesity is becoming a human health crisis at individual and public health levels. It has numerous adverse health effects and is considered as one of the main predisposing factors for the emerging epidemic of noncommunicable diseases [1]. Nowadays, overweight and obesity are growing in populations with different levels of economic situation. It is estimated that by continuing the actual trend, the global prevalence rate of 33.0% for overweight and obesity among adult population (1.3 billion people) in 2005 would reach up to 57.8% (3.3 billion people) by 2030 [2]. The World Health Organization included excess weight, with a prevalence higher than undernutrition, as one of the top 10 health risks worldwide [3]. The rise in the incidence in obesity matches the rise in the use and distribution of industrial chemicals that may have a role in development of obesity. In her interesting review in 2002, Baillie-Hamilton postulated a role for chemical toxins in the etiology of obesity by presenting the coincidence of the obesity epidemic with the noticeable increase of industrial chemicals in the environment over the past four decades. An accumulating body of evidence suggests that substances as endocrine-disrupting chemicals (EDCs) may be linked to the obesity epidemic [4]. EDCs are chemicals that alter