Toxicologie environnementale et analytique

Epigenetic Effects of Endocrine Disrupting Chemicals

Abstract

Mohammad Shahidehnia

Recently, there is increasing evidences supported by animal studies emphasizing that exposure to environmental factors, nutritional conditions, xenobiotic chemicals, reproductive factors and low dose exposure to radiations can alter epigenetic programming and concomitantly enhance the risk of developing diseases. Endocrine disrupting chemicals (EDCs) can influence organization of developing brain, which may appear in expression of species typical social behaviors. Environmental exposures to EDCs are shown to increase the susceptibility against many kind of diseases. Currently, there are already several articles, books and journals about the epigenetic effects of EDCs available in media and internet. The aim of this thesis is to review these articles and to evaluate the possible consequences of being exposed to these agents in our daily life for the process of risk assessment of these chemicals. Epigenetic effects do not change the gene sequence. They affect the gene expression and therefore identification of expression profile in sensitive genes to epigenetic effects may be used as a biomarker for disease and environmental exposure. In the future, theses epigenetic biomarkers may help for early diagnosis of sensitivity of an individual for adult onset disease or maybe used to prevent the disease before the disease’s symptoms develop. When an organism grows and develops, precisely organized chemical reactions activate or deactivate parts of the genome at specific time and locations. The study of these chemical reactions and factors influencing them is called epigenetics. It has been observed that, transgenerationally modified progenies in their life are more prone to different kinds of diseases, such as mammary tumors, prostate disease, kidney disease, testis abnormalities and immune abnormalities. Our health depends on our normal development and reproductive ability. Healthy endocrine system is needed to have normal development and normal reproduction. Few years ago we thought that our life starts with the DNA we receive from our parents, but currents studies have shown that we receive more than just DNA from our parents. Famine, stress, fear and even drug use could all leave chemical marks on parent’s genetic material. Environmental exposure to EDCs during early development and pregnancy can modify epigenomes and induce trans-generationally asthma, autism, cancer, cardiovascular dysfunctions, diabetes, obesity, schizophrenia, infertility, reproductive diseases and dysfunction later in life. There is evidence showing that EDCs can induce epigenetic gene alterations by which these altered genes can be transferred into subsequent generations.