Objective  The oxidative stress and inflammatory response levels of workers occupationally exposed to multiple wall carbon nanotubes (MWCNTs) were studied to develop appropriate preventive measures against this hazard.

Methods  Totally 40 workers with long term occupational exposure to MWCNTs and 40 office staff (as reference) without any records of exposure to occupational hazards (all non-smokers)in this MWCNTs manufacturing company in Guangdong Province were investigated. The airborne concentration of MWCNTs at workplaces was measured. Blood samples were collected for detections of oxidative damage and inflammatory response indices.

Results  The average concentration of MWCNTs in the workplaces was(41.5 ±18.7)μg/m³ and the individual exposure level was (34.4 ±17.7)μg/m³, which were significantly higher than allowable exposure limit (7 μg/m³) recommended by U.S. NIOSH. Levels of 8-hydroxy-2'-deoxyguanosine, 8-epi-prostaglandin F 2 alpha, interleukin 6, interleukin 8, interleukin 33, tumor necrosis factor alpha, osteopontin and eosinophils of exposed workers were all significantly increased compared with those in the reference group (P < 0.01 or P < 0.05). On the contrary, the levels of catalase and glutathione peroxidase of exposed workers were significantly decreased (P < 0.05). No statistical differences were observed among other antioxidant and inflammatory response indices (P > 0.05).

Conclusion  Heavy occupational exposure to MWCNTs might increase the level of reactive oxygen species of workers, and cause oxidative damage to the organism or even damage to DNA of cell lipid membrane. MWCNTs might also increase the levels of several inflammatory response cytokines (such as osteopontin) and eosinophils, which could aggravate respiratory inflammatory responses and asthma symptoms and damage lung function. Workers with exposure to MWCNTs should empower personal protection to reduce the risk of relevant health damages.