Epigenetics, estrogenic endocrine-disrupting chemicals (EDCs), and the brain.

Endocrine-disrupting chemicals (EDCs) are a major public health concern, yet there are gaps in knowledge about the mechanisms for their effects. The brain is incredibly sensitive to small changes in the hormonal environment during early development, with natural sex differences in gonadal hormones shaping the organization of sex-specific neural circuits early in life. EDC exposure during these periods can lead to lifelong impacts on neurobiological health outcomes. Recently, epigenetic mechanisms have been proposed as a potential molecular mechanism for effects of endogenous hormones on the organization of developing brain circuits, leading to speculation that these mechanisms may underlie the long-term impacts of EDC exposure. Of these mechanisms, DNA methylation, associated with gene suppression, and histone marks, associated with gene suppression or activation, will be discussed. We review the evidence for hormones and their role in brain sexual differentiation; underlying epigenetic mechanisms; and how two classes of estrogenic EDCs, BPA and PCBs, may interfere with these processes to change brain structure and function.