Penta bromo diphenyl ether used as flame retardant in upholstery etc., like PCBs interferes with thyroxin metabolism.
It is used by the body to make melanin and several hormones, including epinephrine and thyroxin.
Thyroid gland-An endocrine gland in the neck overlying the windpipe (trachea) that regulates the speed of metabolic processes by producing a hormone, thyroxin.