The rapid development of nanotechnology calls for a timely assessment of the impact of manufactured nanoparticles on environmental settings. This study investigated the association between a C 60 water suspension (nC 60 ) and geosorbents, and their effects on the antibacterial activity of C 60 . The presence of geosorbents reduced the bioavailability of nC 60 and thus its antibacterial activity. Adsorption of humic acid onto nC 60 was also found to eliminate nC 60 toxicity, probably due to coating of nC 60 , which hinders its direct contact with bacteria. These findings indicate the toxicity of nC 60 is controlled by its bioavailability in natural soil settings.