Hormetic Responses of Food-Supplied Pcb 31 to Zebrafish (Danio Rerio) Growth

Hormesis is commonly defined as a beneficial or stimulatory effect caused by exposure to low doses of a chemical known to be toxic at high doses. Hormetic responses of food-supplied PCB 31 (2, 4', 5-Trichlorobiphenyl) was studied by using zebrafish (Danio rerio) growth as an end point. The results in general followed the hormesis hypothesis, PCB 31 at lower concentrations (0.042 μg/g and 0.084 μg/g) exhibited beneficial effects on the growth of zebrafish by weight and length while higher concentrations (10μg/g and 20μg/g) revealed inhibitory effects. The magnitude of stimulatory responses of zebrafish growth by weight and length at lower concentrations (0.01-0.084 μg/g) on days 14 and 21 were in the range 9.09-18.18%; 10-38.09% and 4-14.4%; 6.25-10.93%, respectively as compared to control. Growth and conditions indices also suggested that the zebrafish was healthier at lower concentrations as compared to those at higher concentrations. The results of the present study will elaborate fish toxicological evaluation regarding the hormetic model.