2. Relevance to Public Health 2.1 Background and Environmental Exposures to Vanadium in the United States

Vanadium is the 22 most abundant element in the earth’s crust with an average concentration of 100 ppm. It exists in oxidation states ranging from 2to 5+ with 3+, 4+, and 5+ being the most common oxidation states. Vanadium is primarily used in the production of rust-resistant, spring, and high-speed tool steels; vanadium pentoxide is used in ceramics. Vanadium is released to the environment by continental dust, marine aerosols, volcanic emissions, and the combustion of coal and petroleum crude oils. It is naturally released into water and soil as a result of weathering of rock and soil erosion. Ambient air concentrations of vanadium are low, with urban areas having higher concentrations. Average vanadium concentrations were 3.0–3.7 ng/m in urban areas of Illinois; in rural areas, the vanadium concentrations were 0.8–1.2 ng/m. Higher vanadium levels have been measured in the eastern United States due to the high density of oil fired power plants using vanadium-rich residual fuel oil. An average vanadium air concentration of 620 ng/m was measured in Eastern cities compared to 11 ng/m in cities throughout the United States. Vanadium residence time in the environment is inversely related to the particle size. In water, vanadium is converted from trivalent forms to pentavalent forms. The levels of vanadium in surface water range from 0.04 to 104 μg/L. Vanadium levels of 1.2–1.0 μg/L were measured in tap water samples collected in several U.S. states.