Persistence of vanadium compounds in lungs after intratracheal instillation in rats

Translocation and tissue distribution of two different forms of vanadium compounds, orthovanadate (soluble) and vanadium pentoxide (less soluble), were investigated. Groups of randomly selected rats were injected intratracheally with radiolabeled vanadium (48V) compounds and the animals were sacrificed at 1, 7 and 28 days after treatment. Blood, lungs and other major organs and tissues, namely liver, kidney, spleen, heart, testes, brain, muscle, and bone were sampled and the vanadium contents determined by gamma spectrometry. The less soluble form of vanadium (vanadium pentoxide) was eliminated from the lungs at a slow but exponentially linear rate, whereas the soluble form was translocated rapidly from this organ and exhibited a non-linear decline. Compared to the less soluble form, significantly less vanadium was retained in lungs 7 and 28 days after intratracheal instillation of vanadate. One day after treatment significantly higher concentrations (approximately 4 times) of vanadium after orthovanadate were observed in liver, kidney, spleen and bone compared to the pentoxide. However, tissue residues at 7 and 28 days indicated that both forms of vanadium were rapidly eliminated, except from bone and lungs. Results suggest a prolonged retention of less soluble forms of vanadium and possible health effects following repeated occupational exposure.