In Vivo Induction of Primary DNA Lesions upon Subchronic Oral Exposure to Multi-walled Carbon Nanotubes.

Comet assay was used for testing the potential genotoxicity of multi-walled carbon nanotubes after ingestion. Three rat strains were treated through oral gavage with 50 mg/kg/weekly nanoparticles for 90 days. Induced DNA lesions were studied in lymphocytes at 24 and 48 h following the first treatment. This was repeated at the end of the subchronic treatment in lymphocytes as well as peritoneal macrophages. A significant increase in the level of DNA lesions was measured in lymphocytes of Fischer-344 and Long-Evans rats in the first 24 h. Similar results were observed in their macrophages after 90 days. More significant differences were detected in the sensitivities of the strains. Fisher-344 rats proved the most sensitive and Wistar rats the most tolerant to the genotoxic effects of nanotubes. This may also have human relevance as populations with diverse genetic characteristics might present higher or lower susceptibility to the effects of exposure to ingested nanoparticles.