Mercury Toxicity Quiz

Mercury Toxicity

• Mercury (Hg), also known as hydrargyrum, is a toxic heavy metal.
• Sources include elemental mercury (vapour, dental amalgam, thermometers, sphygmomanometers) and inorganic salts (calomel—mercurous chloride).
• Elemental mercury is toxic only after inhalation; it is poorly absorbed if swallowed.
• Inorganic salts (calomel) are also poorly absorbed. Chronic exposure to mercury chloride in teething lotions and diaper powders can cause pink teeth (Acrodynia).
• Symptoms of Acrodynia include insomnia, hypertension, skin peeling, alopecia, painful and pink hands, and acute renal failure within 24 hours.
• Mercuric chloride is a disinfectant. Mercurial fulminate is used in percussion caps.
• Organic mercurial salts are diuretics and fungicides. Methyl mercury and ethyl mercury are environmental contaminants found in aquatic food chains.
• Mercury reacts with sulfhydryl (-SH) groups, depressing cellular enzymatic mechanisms. Elemental mercury vapor and organic mercurial compounds are very toxic to the central nervous system (CNS), while inorganic mercuric salts are corrosive and nephrotoxic.

Acute Mercury Toxicity

• Clinical Presentation (GIT): Metallic taste, burning sensation from mouth to stomach, nausea and blood-tinged vomiting, tenesmus (leading to diarrhea with mucus and blood), and dehydration and collapse.
• Clinical Presentation (Renal): Acute toxic glomerulonephritis, oliguria, albumin and blood casts, and anuria and renal failure (RF).
• Clinical Presentation (other): Corrosive bronchitis, pulmonary edema, and nervous system manifestations (tremors, increased excitability) from mercury vapor exposure.
• Causes of Death: Dehydration within 24 hours and renal failure within 10 days.

Treatment (Acute Mercury Toxicity)

• Step 1: Remove from further exposure.
• Step 2: Gastric lavage using local antidotes (egg white and skimmed milk forming Hg albuminate precipitate, sodium formaldehyde sulfoxylate as a reducing agent).

Chronic Mercury Toxicity ("Mercurialism")

• Clinical Presentation (GIT): Salivation (an early sign), gray line on the gums, gingivitis (inflamed gums with loose teeth), and gangrene (cancrum oris).
• Clinical Presentation (GIT): Mercurial dysentery (diarrhea with mucus and blood).
• Clinical Presentation (Renal): Albuminuria, hematuria, granular and hyaline casts, oliguria, and renal failure.
• Clinical Presentation (CNS): Kinetic tremors (cerebellar affection), psychic effects (Hg erethism—shyness, loss of confidence, vague fears, and depression/neurosis), skin dermatitis, and mercurialentis (eye lens discoloration).

Treatment (Chronic Mercury Toxicity)

• Prophylactic Treatment: periodic medical examinations for exposed workers, ensuring proper exhaust ventilation, dust filters, and protective clothing (masks, gloves, boots), and intake of proper amounts of calcium (Ca), zinc (Zn), and iron (Fe).
• Curative Treatment:
  • Step 1: Stop further exposure
  • Step 2: Physiological antidotes. (Chelation therapy)
    • D-Penicillamine
    • BAL (British Anti-Lewisite) and its oral analogues (DMSA, DMPS).
  • Step 3: Symptomatic treatments
    • Mouth hygiene
    • Tranquilizers
    • Atropine for salivation
    • Sodium hyposulphite for dermatitis.