Lead poisoning

A 47-year-old man is brought to the office by his son due to increased forgetfulness and fatigue for the past three months. He has also been frequently stumbling and experienced several near-falls while climbing stairs. Review of systems is also notable for abdominal pain and numbness in the patient’s hands and feet. Past medical history is unremarkable, and he does not take any medications. He has been working as an automobile mechanic for the last 20 years. Vitals are within normal limits. The abdomen is soft, nontender, and without organomegaly on physical examination. Neurological examination reveals weakness and reduced pinprick sensation in the bilateral hands and feet. Upper and lower limb reflexes are 2/5. Laboratory testing is shown below. Which of the following is the most likely diagnosis?