US EPA

5030841 

Journal Article 

Enhanced Toxicity of Ozone-Hydrogen Peroxide Mixture 

Svirbely, JL; Dobrogorski, OJ; Stokinger, HE 

1961 

Yes 

American Industrial Hygiene Association Journal
ISSN: 0002-8894 

22 

1 

The toxicity of combined hydrogen-peroxide (7722841) (H202) and ozone (10028156) (O3) exposure was investigated. Male Wistar-rats, Swiss-mice, and hamsters (strain unspecified) were exposed by inhalation to various amounts of O3 and H2O2 alone or in combination. Mortality rate was recorded, and animals were autopsied. Mice were the most sensitive species in all tests, and hamsters were the most resistant. For O3 alone, no deaths occurred at concentrations less than 5 parts per million (ppm). For H2O2 alone, exposure to 113ppm was lethal for some mice. In combined exposures, H2O2 concentrations of 3.3ppm and greater increased the toxic effects of low O3 concentrations. Respiratory tissue damage was also more significant after combined exposure. Exposure to O3 alone provided protection against the toxic effects of subsequent challenge with O3202 mixtures, O3 alone, or H2O2 alone. Preexposure to H2O2 was protective against subsequent O3 or H2O2 challenge. Cross tolerance also developed to cumene-hydroperoxide. Preexposure to O3/H202 mixtures protected against subsequent mixture challenge; the degree of protection was concentration dependent. The authors conclude that O3/H2O2 mixtures are more toxic than either agent alone. Two mechanisms of tissue damage are involved, related to the development of tolerance after repeated exposures. A common mechanism of action exists for peroxides, possibly involving immunochemical reactions on substances such as serotonin, adrenalin, or histamine.