DI-ISONONYL PHTHALATE (DINP) AND DI-(2-ETHYLHEXYL)-PHTHALATE (DEHP) DISRUPTS ENDOCRINE FUNCTIONS IN THE FRESHWATER FISH, OREOCHROMIS MOSSAMBICUS (PETERS, 1852)

Abstract

Endocrine disrupting effects of two phthalate plasticizers namely di-isononyl-phthalate (DINP) and di-(2-ethylhexyl)-phthalate (DEHP) were evaluated in the freshwater fish, Oreochromis mossambicus. Male and female fishes were grouped separately and exposed to sublethal concentration of DINP (300 ppm) and DEHP (60 ppm) for 4, 7, 14, 30 and 60 days. At the end of every exposure period, blood serum was collected to determine the levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), thyroid stimulating hormone (TSH), cortisol, testosterone and estradiol, and was compared with the respective control groups. The main findings of the study indicated that the levels of FSH and LH initially increased significantly (P less than 0.05) after the phthalates exposure, and decreased after 7 days onwards in both male and female fishes when compared to the corresponding control groups. DINP and DEHP treatment caused significant (P less than 0.05) decrease in the levels of TSH, cortisol and testosterone in time-dependent manner whereas the level of estradiol showed significant (P less than 0.05) reduction after 14 days of exposure in female fish without any significant changes in the male fish. The results suggest that exposure to phthalate plasticizers disrupts the hypothalamo-pituitary endocrine functions and this could be related to abnormal reproductive functions in the fish.