Comparison of Toxicity of Nano and Bulk Titanium Dioxide on Nile Tilapia (Oreochromis niloticus): Acetylcholinesterase Activity Modulation and DNA Damage.

This study compared effects of low concentrations (0.05 and 0.1 mg/L) of nano-TiO and bulk-TiO on brain, gill and liver acetylcholinesterase (AChE) and erythrocytic DNA of Nile tilapia over 7 and 14 days exposure. Both TiO forms did not affect brain AChE activities. Bulk-TiO induced elevation of gill AChE activities only after 7 days while nano-TiO had no effect. Liver AChE activities were increased by 0.1 mg/L bulk- and nano-TiO to similar extents. At 7 days, erythrocytic DNA damage was induced only by 0.1 mg/L nano- and bulk-TiO to similar extents, but damage was not repaired to control levels at 7 days recovery period. At 14 days continuous exposure, DNA damage was induced by 0.05, 0.1 mg/L nano-TiO and 0.1 mg/L of bulk-TiO to similar extents. Results show that both forms of TiO can pose genotoxic hazards to fish populations under sub-chronic exposure. However, their neurotoxic potential was not evident.