Effects of tetrabromobisphenol-A and pentabromophenol on thyroid hormones and deiodinases of goldfish, Carassius auratus

To test the thyroid disrupting effects of brominated flame ratardants in vivo, goldfish (Carassius auratus) were exposed to 0.5 mg·L^-1 tetrabromobisphenol-A (TBBPA) and 0.1 mg·L^-1pentabromophenol (PBP) singly for 28 d. Plasma thyroid hormone levels and liver deiodinase activities were detected using microparticle enzyme immunoassay and radioimmunoassay. The results showed that TBBPA could decrease plasma TT₄and TT₃levels, and increase plasma rT₃ level and liver IDs activities. The disturbance of PBP was less than that of TBBPA. No effects were observed on the plasma TT₃ level or liver ID2 activity in groups exposed to PBP. It was deduced that TBBPA and PBP could interfere with the homeostasis of fish thyroid hormones, which might arise from interference with the binding of thyroid hormones to transthyretin.