The thyroid system controls several developmental processes and participates in
many physiological functions such as metabolic regulation, energy homeostasis, bone
remodeling, reproduction, cardiac function and mental status in both children and adults.
Thyroid function is regulated through the interaction between the hypothalamus, the
pituitary and the thyroid. A large number of compounds such as pesticides, drugs, heavy
metals, cosmetics, industrial chemicals and natural compounds have been shown to disrupt
thyroid system homeostasis by acting on diverse regulation points of thyroid hormones
metabolism, binding to thyroid receptors or altering gene transcription regulated through
thyroid hormones among other mechanisms involved. There is special concern about
thyroid disruptors because even slight variations in thyroid homeostasis may negatively
affect human health, particularly during critical periods of vulnerability such as
development and senescence or in sensitive population groups. This chapter focusses on
known disrupting mechanisms and key factors influencing them.
Keywords: Endocrine disruption, thyroid hormones.
