Cobalt accumulation in horses following repeated administration of cobalt chloride.

The current urine cobalt threshold was only effective at detecting acute cobalt exposure while the plasma cobalt threshold was able to consistently identify chronic high-level cobalt exposure and potential cobalt misuse. The threshold values legislated for urine cobalt do not correlate with those set for plasma. The acute nature of urinary cobalt excretion provides a relatively small window through which cobalt administration is detected. Plasma and red cell cobalt concentrations can provide a clearer picture of potential cobalt misuse.