A 50-year-old man who works in a battery manufacturing plant presents with fatigue, abdominal cramps, and memory problems. He reports difficulty gripping objects and recent episodes of constipation. His job involves melting and assembling lead-based materials in an environment with minimal ventilation. On examination, he has wrist drop, pallor, and bluish discoloration along the gumline (Burton’s lines). Laboratory findings reveal microcytic anemia with basophilic stippling and an elevated blood lead level.Which of the following is the most likely route of lead exposure in this patient?
