We did a clinical trial of succimer to treat moderately lead poisoned children. We found no effect of succimer treatment on cognition or behavior, reported previously. Recently, we have arranged with CDC to analyze blood samples collected in this project for methyl mercury, inorganic mercury, and cadmium, which allowed a randomized trial of succimer for chelation of these compounds without enrolling any new subjects or collecting any specimens. Succimer does not appear to be an efficacious chelating agent for mercury or cadmium.