4-tert-octylphenol and 17beta-estradiol applied by feeding to flounder Platichthys flesus: induction of vitellogenin and accumulation in tissues

In order to simulate a possible natural administration route of xenoestrogens male flounder Platichthys flesus were exposed via the diet to the alkylphenol 4-tert-octylphenol. Treatment with 4-tert-octylphenol (10, 50 and 100 mg OP kg(-1) BW) or 17beta-estradiol (0.05 mg kg(-1) BW) every second day during a period of 11 days resulted in a significant increase in plasma vitellogenin (Vtg) concentrations. The induction of Vtg was greatest in the fish receiving 50 mg OP kg-' BW. A significant accumulation of 4-tert-octylphenol was found in liver and muscle tissue of the OP treated groups. The tissue concentrations of 4-tert-octylphenol and the plasma vitellogenin concentration were positively correlated. The results show that 4-tert-octylphenol accumulates in liver and muscles of flounder P. flesus, and exerts estrogenic effects such as vitellogenin induction.