Inorganic cobalt supplementation: Prediction of cobalt levels in whole blood and urine using a biokinetic model

Soluble cobalt (Co) supplements with recommended daily doses up to 1000 μg Co/day are increasingly being marketed to consumers interested in healthy living practices. For example, some athletes may consider using Co supplements as blood doping agents, as Co is known to stimulate erythropoesis. However, the distribution and excretion kinetics of ingested Co are understood in a limited fashion. We used a Co-specific biokinetic model to estimate whole blood and urine Co levels resulting from oral exposure or ingestion of Co in amounts exceeding typical dietary intake rates. Following 10 days of Co supplementation at a rate of 400 to 1000 μg/day, predicted adult Co concentrations range from 1.7 to 10 μg/L in whole blood, and from 20 to 120 μg/L in urine. Chronic supplementation (?1 year) at a rate of 1000 μg Co/day is predicted to result in blood levels of 5.7 to 13 μg/L, and in urine levels from 65 to 150 μg/L. The model predictions are within those measured in humans following ingestion of known doses. The methodology presented in this paper can be used to predict urinary or blood Co levels following acute or chronic occupational incidental ingestion, medicinal therapy, supplemental intake, or other non-occupational exposures.