be considered toxic. Tetravalent VOSO4 has been reported to be at least 5 times more toxic than trivalent V2O3. The US Occupational Safety and Health Administration (OSHA) has set an exposure limit of 0.05 mg/m3 for vanadium pentoxide dust and 0.1 mg/m3 for vanadium pentoxide fumes in workplace air for an 8-hour workday, 40-hour work week. The US National Institute for Occupational Safety and Health (NIOSH) has recommended that 35 mg/m3 of vanadium be considered immediately dangerous to life and health, that is, likely to cause permanent health problems or death. Vanadium compounds are poorly absorbed through the gastrointestinal system. Inhalation of vanadium and vanadium compounds results primarily in adverse effects on the respiratory system. Quantitative data are, however, insufficient to derive a subchronic or chronic inhalation reference dose. Other effects have been reported after oral or inhalation exposures on blood parameters, liver, neurological development, and other organs in rats. There is little evidence that vanadium or vanadium compounds are reproductive toxins or teratogens. Vanadium pentoxide was reported to be carcinogenic in male rats and in male and female mice by inhalation in an NTP study, although the interpretation of the results has recently been disputed. The carcinogenicity of vanadium has not been determined by the United States Environmental Protection Agency. Vanadium traces in diesel fuels are the main fuel component in high temperature corrosion. During combustion, vanadium oxidizes and reacts with sodium and sulfur, yielding vanadate compounds with melting points as low as 530 °C, which attack the passivation layer on steel and render it susceptible to corrosion. The solid vanadium compounds also abrade engine components. See also References Further reading External links Videos Vanadium at The Periodic Table of Videos (University of Nottingham) Research papers ATSDR – ToxFAQs: Vanadium Vanadium concentration in seawater and estuary environments is around 1.5–3.3 ug/kg Vanadium speciation and cycling in coastal waters Ocean anoxia and the concentrations of molybdenum and vanadium in seawater Chemical elements Transition metals Dietary minerals Restorative dentistry Chemical elements with body-centered cubic structure Native element minerals