Chemical Information Review Document for Oral Exposure to Tetravalent and Pentavalent Vanadium Compounds

Vanadium (CAS No. 7440-62-2) is an element that exists in a number of oxidation states ranging from -1 to +5 and can be found in various locales around the world. Absorption of vanadium from the gastrointestinal tract is poor and most ingested vanadium is typically converted to vanadyl. Excretion of absorbed vanadium is primarily via urine while unabsorbed vanadium is mainly eliminated in feces. Studies indicate that toxicity is dependent on the valence of vanadium, increasing with increasing valence. Thus, pentavalent vanadium is more toxic than tetravalent vanadium. Acute toxicity studies indicate that administration of vanadium compounds is associated with locomotor impairments and effects on respiratory and cardiovascular systems. Short-term studies indicate that while pentavalent vanadium compounds produced effects on a variety of hematological markers, tetravalent compounds do not appear to have similar effects. Both valence states are associated with alterations in body weight, and food and fluid intake after short-term oral administration. Chronic studies with vanadyl sulfate indicated effects on body weight in animals while studies with sodium metavanadate showed effects on urinary markers. A few studies indicated that toxicological effects of vanadium compounds can be modified by the presence of other compounds. Tetravalent vanadium compounds were shown to have impacts on the structures within reproductive organs, survival rate of weanlings, sperm density and motility, fertility, and litter size. Pentavalent vanadium compounds were shown to impact maternal body weight. Conflicting outcomes on the impact of vanadium exposure (via drinking water) on tumor development were observed in two studies. Over 20 studies have shown that vanadium compounds exert chemopreventive effects against chemically-induced carcinogenesis. Genotoxicity studies indicate that vanadium compounds can increases the number of cells with hypoploidy, the number of aberrant cells, and the number of micronucleated polychromatic erythrocytes. Immunotoxicity in animals was observed after administration of pentavalent vanadium compounds. Studies in offspring of dams administered sodium metavanadate indicated neurotoxicological effects, suggesting placental transfer of the chemicals to the fetuses.