Lead can be absorbed after inhalation or ingestion and is toxic to most organ systems. Management involves avoidance of exposure and, in more severe cases, chelation therapy with either sodium calcium edetate or dimercaptosuccinic acid. Iron poisoning causes its metabolic effects in proportion to the concentrations of free iron, although individual responses vary. Toxicity is therefore related to the dose ingested. Iron concentrations can rise and fall, making plasma concentrations difficult to interpret in acute poisoning.