Chapter 2: Epigenetic Reprogramming by Endocrine Disrupting Chemicals

Public concern over endocrine-disrupting chemicals (EDCs) and their effects on human and environmental health has increased in recent years. Exposure to EDCs has been associated with increased risk of endocrine-related cancers, diabetes, adiposity, and reduced fertility in humans, abnormalities in bone tissue in livestock, and modified sex ratios in wildlife. Moreover, accumulating evidence indicates that exposure to relatively low doses of EDCs early in life could have lasting effects on individual health. However, in spite of increased scrutiny and investigation, the mechanistic basis by which EDCs induce long-term or even transgenerational effects has yet to be fully elucidated. Epigenetic marks, which are heritable but reversible chromatin modifications that can lead to alterations in gene expression, are one of the mechanisms thought to be responsible for these effects. As the epigenome is responsive to environmental stimuli, it is thought to be an integral link between genetic and environmental risk factors that lead to disease. In this chapter, we provide an overview of epigenetic regulation, and a review of EDCs known to affect the epigenome. We also discuss the advantages and challenges of applying epigenetic knowledge in risk assessments for EDC exposure, and measures that can be taken to overcome these challenges.