Co-exposure with fullerene may strengthen health effects of organic industrial chemicals

In vitro toxicological studies together with atomistic molecular dynamics simulations show that occupational co-exposure with C-60 fullerene may strengthen the health effects of organic industrial chemicals. The chemicals studied are acetophenone, benzaldehyde, benzyl alcohol, m-cresol, and toluene which can be used with fullerene as reagents or solvents in industrial processes. Potential co-exposure scenarios include a fullerene dust and organic chemical vapor, or a fullerene solution aerosolized in workplace air. Unfiltered and filtered mixtures of C-60 and organic chemicals represent different co-exposure scenarios in in vitro studies where acute cytotoxicity and immunotoxicity of C-60 and organic chemicals are tested together and alone by using human THP-1-derived macrophages. Statistically significant co-effects are observed for an unfiltered mixture of benzaldehyde and C-60 that is more cytotoxic than benzaldehyde alone, and for a filtered mixture of m-cresol and C-60 that is slightly less cytotoxic than m-cresol. Hydrophobicity of chemicals correlates with co-effects when secretion of pro-inflammatory cytokines IL-1 beta and TNF-alpha is considered. Complementary atomistic molecular dynamics simulations reveal that C-60 co-aggregates with all chemicals in aqueous environment. Stable aggregates have a fullerene-rich core and a chemical-rich surface layer, and while essentially all C-60 molecules aggregate together, a portion of organic molecules remains in water.