SYNERGISTIC TOXIC EFFECTS CAUSED BY THE COEXPOSURE OF ZnO AND TiO2 NANOPARTICLES IN CARP FISH

Abstract

Nanoparticles are an emerging class of pollutants due to their extensive use in different products. They enter the environment directly or indirectly during the manufacturing lifecycle as well as by-products that contain nanoparticles, for example,sunscreens and paints. Nano zinc oxide and titanium dioxide are extensively utilized worldwide, and their production is expected to increase further. The study evaluates the toxicity of nano zinc oxide individually and in combination with nano titania in common carp. This fish species is economically valued worldwide as it is a source of protein and easily available. It is also susceptible to a wide range of water contaminants. Titanium dioxide nanoparticles enhanced the lethality of zinc oxide nanoparticles as the LD50 reduced from 351 to 326 mg/L. Zinc oxide nanoparticles accumulation was found to be augmented in the presence of titanium dioxide nanoparticles. The maximum accumulation was observed in the intestine of fish, while the lowest was observed in the muscle of fish. Initially, zinc oxide nanoparticle reduces the ROS in the fish body however with increasing dosage and time, defense mechanism suppresses, and an increase was found in the ROS and a direct increase was found in the ROS in the presence of titanium dioxide nanoparticles (p<0.05). The maximum histopathological lesions were observed in co-exposure treatment group and the most common alterations were the shortening and curling of secondary lamella, partial fusion of lamella, and edema. The biochemical indices glucose, triglycerides and alanine transaminase significantly increased due to TiO2 NPs. However, total protein decreased in the combined exposure group. The findings highlight the significance of considering the co-occurrence and interplay of nanoparticles in comprehending their toxicity in organisms.