Titanium dioxide nanoparticles promote histopathological and genotoxic effects in Danio rerio after acute and chronic exposures

Abstract

Titanium dioxide nanoparticles (TiO2-NPs) are among the most used nanomaterials worldwide, but studies evaluating its genotoxicity and histopathological effects are scarce, dealing with short exposure times and low concentrations for human use. The aim was to evaluate TiO2-NPs genotoxicity and histological alterations in the intestine and liver of zebrafish after exposure to human consumption compatible concentrations. Fishes were acutely (96 hours) and chronically (30 days) exposed to 5.0, 20 and 40 mg L-1 of TiO2-NPs and later euthanized for organ and blood analysis through histological procedures and the micronucleus test, respectively. An increase in the thickness of intestinal villi was observed after acute and chronic exposure in the higher concentrations. The liver showed an increase in vacuolated hepatocytes after both exposures, besides an increase in hepatocytes with peripheral nucleus. Genotoxicity was only observed after chronic exposure, demonstrated by the increase in micronucleus and cell buddings. These findings indicate that TiO2-NPs cause histopathological damage even in acute exposures, as the intestine serves as a barrier for NPs and the liver is an organ that accumulates Ti. Genotoxicity was possibly mediated by reactive oxygen species through chronic inflammation, leading to tissue damage and carcinogenesis in longer exposures that represents human exposure time.