A shipyard painter using antifouling paint develops cerebellar ataxia, tunnel vision, and sensorineural deafness. Blood investigations show elevated urinary mercury. The organic mercury compound most likely responsible is:
- A Inorganic mercury (HgCl₂)
- B Methylmercury ✓
- C Elemental mercury vapor
- D Phenylmercury acetate
Explanation
Methylmercury (organic mercury) preferentially crosses the blood-brain barrier and accumulates in the CNS, causing Minamata disease features: cerebellar ataxia, constriction of visual fields ('tunnel vision'), sensorineural deafness, dysarthria, and paresthesias (Hunter-Russell syndrome). While antifouling paints historically used tributyltin and phenylmercury, the question's clinical picture of CNS toxicity with cerebellar + sensory + auditory involvement points to methylmercury. Elemental mercury vapor primarily causes tremor and erethism; inorganic mercury salts cause nephrotic syndrome and gastrointestinal damage. The classic occupational scenario for methylmercury is fish consumption or industrial exposure to organic mercury compounds.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.