Acute effects of exposure to vapors of hydrogen peroxide in humans.

Hydrogen peroxide is a reactive chemical mainly used for bleaching, as a disinfectant, and as a general oxidizing agent. The aim of this study was to investigate subtle acute effects of inhaled hydrogen peroxide vapors. Eleven healthy volunteers were exposed to 0 (clean air), 0.5 and 2.2 ppm for 2h at rest. Symptoms related to irritation and central nervous system effects were rated with Visual Analog Scales. The ratings varied considerably but were generally low and with no significant differences between exposure conditions, although the ratings of smell (p=0.09, Friedman's test), nasal irritation (p=0.06) and throat irritation (p=0.06) showed borderline tendencies to increase at 2.2 but not at 0 and 0.5 ppm. Nasal airway resistance increased after exposure to 2.2 ppm hydrogen peroxide (p=0.04, paired t-test) but not after 0.5 ppm. No exposure-related effects on pulmonary function, nasal swelling, breathing frequency and blinking frequency were detected. Furthermore, no clear effects were seen on markers of inflammation and coagulation (interleukin-6, C-reactive protein, serum amyloid A, fibrinogen, factor VIII, von Willebrand factor and Clara cell protein in plasma). In conclusion, our study suggests that hydrogen peroxide is slightly irritating at 2.2 ppm, but not at 0.5 ppm.