Oxidative damage and genotoxic effect in mice caused by sub-chronic exposure to low-dose volatile organic compounds

Volatile organic compounds (VOCs) are widely used as constituents of household chemicals. Although adverse health effects have been reported, long-term exposure to low-level VOCs mixture has not been studied. Especially, there is a lack of substantial information on the sensitive biomarkers and carcinogenic markers. In the present study, we examined oxidative stress and genotoxic effects of sub-chronic low-dose VOCs mixture (formaldehyde, benzene, toluene and xylene). Male Kunming mice were exposed to 0 (control) and three different doses of VOCs mixture (group 1S, 5S and 10S) for 90 d (2 h/d). Group 1S is 0.10, 0.11, 0.20 and 0.20 mg/m³, group 5S is 0.50, 0.55, 1.00 and 1.00 mg/m³, group 10S is 1.00, 1.10, 2.00 and 2.00 mg/m³, which, respectively, corresponded to 1, 5 and 10 times of indoor air quality standard (IAQS) in China. One day following VOCs exposure, oxidative stress markers in lung, 8-hydroxy-2'-deoxyguanosine in bronchoalveolar lavage fluid and genotoxicity (DNA damage) in liver were examined. Results showed that exposure to VOCs (IAQS dose) resulted in oxidative damages of lung, which were supported by the significant changes on reactive oxygen species, reduced glutathione (GSH), GSH S-transferase, total antioxidative capacity, malondialdehyde, protein carbonyl and nitric oxide (NO). Moreover, oxidative stress markers in group 5S and 10S (except NO) in lung were affected significantly. In addition, VOCs exposure also induced significantly DNA damage in liver. Our study suggested long-term VOCs inhalation at low levels caused oxidative stress and genotoxicity response in mice. Since effects were seen at the current IAQS level, further studies below this level are necessary.