Benzo[a]Pyrene (BaP) is a ubiquitous polycyclic aromatic hydrocarbon (PAH) that has been shown to disrupt themetabolism of thyroid hormone. Then, the present investigation aimed to study the effects of BaP on thyroidfunction in Liza abu. Fish were injected with 2, 10 and 25 mg/kg-bw of BaP. Samples were taken from blood,thyroid and muscle tissues at days 1, 2, 4, 7, and 14. Blood was evaluated for changes in the plasma levels ofTSH, T3 and T4. Also, BaP bioaccumulation in the fish muscle was measured. Thyroid tissues were processed forroutine histology. BaP concentration in the muscle of treated fish reached a maximum level after 4 days.Exposure of fish to BaP resulted in a significant decrease in T3 and T4 plasma level and increase in TSH con-centration up to day 4. Also some pathological alterations were observed in BaP-exposed fish such as hemor-rhage and increased number of large follicles with squamous epithelium. In conclusion, according to the resultsof the present investigation, short term exposure to sublethal concentrations of BaP significantly affected thyroidfunction in fish. The results revealed BaP ability to alter thyroid function.
