Prenatal Exposures to Multiple Thyroid Hormone Disruptors: Effects on Glucose and Lipid Metabolism

Table 2

Risk assessment of TH-EDCs and their effect on TH regulation in pregnancy.

Endocrine disruptors	Thyroid hormone-EDCs	Sources of exposure	Mode of exposure	Target tissues	Effect on TH regulation	References
Nonpersistent; organic; chemicals	Phthalates	Medical equipment, pesticides, and cosmetics	Ingestion, inhalation, and dermal exposures	Placenta, cord blood, and neonatal meconium	Impaired iodine uptake, inhibition of TH homeostasis	[16–18]
	Bisphenol A	Food can linings, dental sealants, and plastics	Ingestion, dermal exposures	Serum, amniotic fluid, and placenta	Binds TTR and inhibits TPO, T3 antagonist	[16, 19–21]
	Triclosan	Clothing, cosmetics, and detergents	Ingestion, dermal exposures	Urine, serum, and breast milk	Alters TH actions	[22–24]
Persistent; organic; chemicals	Flame retardants	Furniture, electronics, house dust, and foods	Inhalation, ingestion	Serum, milk, and cord blood	Disrupt TH signalling, alter TH levels, and inhibit TH sulfotransferase, TSH, and deiodinase activities	[25–27]
	Dioxins	By-products of industrial and environmental processes	Ingestion of contaminated dairy products	Fat tissue, breast milk	Alter TH and TSH levels and TPO and bind TTR	[28, 29]
	Polychlorinated biphenyls	Insulating materials, heat-transfer systems, lubricants, and paints	Dermal exposures, ingestion, and inhalation	Placenta, serum, adipose, and breast milk	Alter TH and TSH levels, bind TTR, and alter TH-responsive genes	[30–32]
	Perchlorates	Inflation systems, fireworks, nitrate fertilizers, and oxidants in propelling rockets and missiles	Drinking contaminated water, ingestion, and inhalation	Breast milk, urine	Inhibit iodine uptake via sodium iodide symporter (NIS) and alter TH and TSH levels	[33–35]
	Phytoestrogens	Soy rich foods	Ingestion		Decrease iodine accumulation, inhibit TPO activity, act as TR agonist or antagonist, and alter TH levels	[36, 37]