BAL = dimercaprol. Bal is "british anti-lewisite", a prescription medication given by injection for the removal of heavy metals such as lead and mercury. (it also combats lewisite, an arsenic-based chemical warfare agent). Overdose symptoms include nausea, vomiting, drowsiness, and seizure (convulsions). Treatment is supportive with protection of the airway, intravenous fluids, and a tincture of time.