Which form of mercury poisoning is most closely associated with dermal and neurologic signs?

• A. Mercuric salts
• B. Alkyl mercurials
• C. Elemental mercury
• D. All forms equally cause dermal signs

Answer: (B)

Organic mercury compounds are highly lipophilic and readily cross both skin and the blood–brain barrier. When exposure occurs through the skin, these alkyl mercurials are absorbed systemically and can accumulate in the brain, causing neurologic signs such as tremors, paresthesias, and ataxia. At the same time, their contact with the skin can produce local dermal irritation or dermatitis. In contrast, inorganic mercuric salts are less readily absorbed through the skin and mainly cause GI/renal toxicity after ingestion, and elemental mercury’s neurologic effects are predominantly from inhalation rather than skin contact. So the combination of dermal involvement with neurotoxicity points most clearly to alkyl mercurials.