A simulation model describing the metabolism of inhaled and ingested selenium compounds

Organ distribution and retention of the trace element selenium were studied in rats after inhalation of selenious acid and elemental selenium aerosols. A simulation model of selenium metabolism was developed from data obtained. Although the rate of absorption of these two compounds into blood was different, once absorbed both chemical forms behaved identically. This indicates that both compounds joined the same selenium metabolic pool. The simulation model was extended to estimate the levels of selenium in people inhaling selenium compounds normally found in urban atmospheres and in individuals exposed to selenium compounds in the workplace. Predictions of the model for uptake and organ retention of selenium from the environment were compared to measured organ burdens in humans. Inhalation of selenium compounds at levels normally present in urban atmospheres does not contribute significantly to human body burdens of selenium. The most probable source of selenium in human tissues is due to ingestion of selenium in food. However, selenium present in the workplace, in concentrations at the timeweighted threshold limit value, may pose an inhalation hazard to at least some of the workers.