This study evaluated the toxic effects of titanium dioxide (TiO2) bulk salt as well as its nanoparticles (NPs) in anatase phase with mean crystallite size of 36.15 nm in male Sprague-Dawley rats by subcutaneous injections at four different dose levels of either control (0), 50, 100 or 150 mg/kg of body weight (BW) of rat for 28 days on alternate days. Animal mortality, haematology, micronucleus assay, liver histology and activities of liver tissue damage markers like, alkaline phosphate (ALP), alanine transaminase (ALT), aspartate transaminase (AST), as well as oxidative stress indicators like superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), reduced glutathione (GSH) and lipid peroxidation (LPO) were investigated. The study revealed significant differences (P < 0.05) among control and experimental groups in all the haematological parameters at the end of experiment. Significantly elevated levels (P < 0.05) of ALT, AST and ALP were found for the group treated with TiO2 NPs at the dose of 150 mg/kg of body weight as compared to control. TiO2 and TiO2 NPs caused dose-dependent genotoxicity in the blood cells of the treated rat as revealed by micronuclei test. The highest frequency of micronuclei was observed in rats treated with NPs at the dose of 150 mg/kg BW which was significantly different (P < 0.001) from all other experimental groups after 28 days of exposure. Similarly, all the treatments showed dose-dependent oxidative stress in the treated rats. However, the significantly high decline in the activities of CAT, SOD, and GST as well as elevation in malondialdehyde and GSH was observed in the group receiving NPs at the rate of 150 mg/kg BW. TiO2 also caused histological alterations in the liver. The study revealed that higher dose of TiO2 NPs exerted significantly harmful effects on liver and blood as compared to its lower doses as well as from all other doses of their bulk counterparts.
Keywords: Histological changes; Lipid peroxidation; Liver function tests; Micronucleus assay; Nanoparticles; Oxidative stress; TiO2.