Environmental Pollutants and Metabolic Disorders: The Multi-Exposure Scenario of Life

Abstract

Obesity and diabetes have reached epidemic proportions the past few decades and continue to progress worldwide with no clear sign of decline of the epidemic. Obesity is of high concern because it is the main risk factor for a number of non-communicable diseases such as cardiovascular diseases and type 2 diabetes. Metabolic diseases constitute a major challenge as they are associated with an overall reduced quality of life and impose a heavy economic burden on countries. These are multifactorial diseases and it is now recognized that environmental exposure to man-made chemical pollutants is part of the equation. Yet, risk assessment procedures are based on a one-by-one chemical evaluation which does not meet the specificities of the multi-exposure scenario of life, e.g., a combined and long-term exposure to even the smallest amounts of chemicals. Indeed, it is assumed that environmental exposure to chemicals will be negligible based on the low potency of each chemical and that they do not interact. Within this mini-review, strong evidences are brought that exposure to low levels of multiple chemicals especially those shown to interfere with hormonal action, the so-called endocrine disrupting compounds do trigger metabolic disturbances in conditions in which no effect was expected if considering the concentration of each individual chemical in the mixture. This is known as the cocktail effect. It means that risk assessment procedures are not protective enough and thus that it should be revisited for the sake of Public Health.

Methyl Mercury, Adipokines, 3T3-L1 Cells and Diabetes

“…This understanding will add data to the debate about mercury or other contaminants and their role at the biochemical level in metabolic syndrome. Specifically, this type of research will further develop a model system to link specific environmental contaminants to metabolic syndrome and associated diseases [6,15].…”

“…The idea of using natural food in a model anti-oxidant system to study the mitigating effects on adipokine secretion will increase the possibility of a potential neutraceutical treatment options for insulin resistance [57]. Using a defined antiinflammatory compound would advance the current common approach of testing complex extracts and mixtures [15].…”

“…Since low levels of MeHg are present in many foods, and is fat soluble, it is reasonable to investigate its relationship to adipokines. A cell culture model that can investigate MeHg mixtures with low levels of other contaminants would be useful [15].…”

“…Since there is an increasing variety of the type of metals which the general population is exposed too, a significant public health issue understanding the impact of various metals, as well as mixtures, on the etiology of hypertension and diabetes. Studies in model systems are needed to clarify the underlying mechanisms such as the role of the balance of antioxidants [15,16].…”

Assessment of metals induced histopathological and gene expression changes in different organs of non-diabetic and diabetic rats

“…Here, we extended our analysis employing histopathological and qRT-PCR (for Bcl 2 and Caspase-3 expression) analyses to investigate the metal alone as well as metal mixture induced toxicity in different organs including heart, liver, pancreas, and spleen in addition to the kidney of diabetic and non-diabetic Wistar rats. Diabetes is a complex www.nature.com/scientificreports www.nature.com/scientificreports/ metabolic disorder 13 and it is well documented that different toxicants involve in the induction of insulin resistance and contribute to diabetes-related substantial mortalities 23,24 . Apoptosis can be induced by a variety of stimuli including chemotherapy agents 25 , ultraviolet (UV) radiations 26 , polychlorinated biphenyls 27 , infection by pathogens 28 , polycyclic aromatic hydrocarbons (PAHs) 29 and heavy metals 30,31 .…”