Individual and combined toxicity of carboxylic acid functionalized multi-walled carbon nanotubes and benzo a pyrene in lung adenocarcinoma cells.

Co-exposure to carboxylic acid functionalized multi-walled carbon nanotubes (F-MWCNTs) and polycyclic aromatic hydrocarbons (PAHs) such as benzo a pyrene (BaP) in ambient air have been reported. Adsorption of BaP to F-MWCNTs can influence combined toxicity. Studying individual toxicity of F-MWCNTs and BaP might give unrealistic data. Limited information is available on the combined toxicity of F-MWCNTs and BaP in human cells. The objective of the present work is to evaluate the toxicity of F-MWCNTs and BaP individually and combined in human lung adenocarcinoma (A549 cells). The in vitro toxicity is evaluated through cell viability, the production of reactive oxygen species (ROS), apoptosis, and the production of 8-OHdG assays. Adsorption of BaP to F-MWCNTs was confirmed using a spectrophotometer. The results indicated that the F-MWCNTs and BaP reduce cell viability individually and produce ROS, apoptosis, and 8-OHdG in exposed cells. Stress oxidative is found to be a mechanism of cytotoxicity for both F-MWCNTs and BaP. Combined exposure to F-MWCNTs and BaP decreases cytotoxicity compared to individual exposure, but the difference is not statistically significant in all toxicity assays; hence, the two-factorial analysis indicated an additive toxic interaction. Adsorption of BaP to F-MWCNTs could mitigate the bioavailability and toxicity of BaP in biological systems. Considering the mixture toxicity of MWCNTs and BaP is required for risk assessment of ambient air contaminants.