Which statement best describes the toxicokinetics of lead?

• A. Absorption high; deposition in liver; excretion via feces
• B. Absorption moderate; deposition in kidney; excretion via urine
• C. Absorption high; deposition in brain; excretion via urine
• D. Absorption low; deposition in soft tissues and bone; excretion via bile/urine

Answer: (D)

Lead toxicokinetics involve relatively low gastrointestinal absorption (especially in adults), rapid distribution to soft tissues followed by long-term storage in bone, and slow elimination mainly through the kidneys with some biliary (bile) excretion. The bone acts as a reservoir, so lead can remain in the body for years and be released back into circulation over time, contributing to chronic effects. This pattern—low absorption, deposition in bone and some soft tissues, and excretion via urine and bile—best fits lead pharmacokinetics. In contrast, high absorption with fecal excretion, primary brain or liver deposition, or exclusive kidney storage does not match how lead behaves in the body.