Vanadium pentoxide (
V2O5) is a slightly soluble compound found in airborne particle emissions from metallurgical works and oil and
coal burning. Because the carcinogenic potential of
V2O5 was not known, F344/N rats and B6C3F1 mice (N=50/sex/species) were exposed to
V2O5 at concentrations of 0, 0.5 (rats only), 1, 2, or 4 (mice only) mg/m3, by whole-body inhalation for 2 years. The survival and
body weights of rats were minimally affected by exposure to
V2O5. The survival and
body weights of male mice exposed to 4 mg/m3 and
body weights of all exposed groups of female mice were lower than the controls. Alveolar/bronchiolar (A/B)
neoplasms occurred in male rats exposed to 0.5 and 2 mg/m3 at incidences exceeding the National Toxicology Program (NTP) historical control ranges. A marginal increase in A/B
neoplasms was also observed in female rats exposed to 0.5 mg/m3. Increases in chronic
inflammation, interstitial
fibrosis, and alveolar and bronchiolar
hyperplasia/
metaplasia and squamous
metaplasia were observed in exposed male and female rats. A/B
neoplasms were significantly increased in all groups of exposed mice. As with rats, increases in chronic
inflammation, interstitial
fibrosis, and alveolar and bronchiolar epithelial
hyperplasia were observed in mice exposed to
V2O5. Thus,
V2O5 exposure was a pulmonary
carcinogen in male rats and male and female mice. The marginal
tumor response in the lungs of female rats could not be attributed conclusively to exposure to
V2O5. These responses were noted at and slightly above the OSHA permissible occupational exposure limit of 0.5 mg/m3 (dust) (National Institute for Occupational Safety and Health, NIOSH Pocket Guide to Chemical Hazards, U.S. Department of Health and Human Services, Washington, DC, 1997, p. 328).