Emergency Medicine Book

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Mercury PoisoningAka: Mercury Toxicity, Mercury Content in Fish, Mercury

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  1. Background
    1. Mercury is the only metal liquid at room temperature
    2. Mined in Spain as Cinnabar
    3. Contaminates water and air via disposal of items
      1. Batteries
      2. Polyvinyl chloride
      3. Latex paint
  2. Pathophysiology
    1. Sources of exposure
      1. Mercury-containing device spill
      2. Disk battery ingestion
      3. Laxative abuse
      4. Repeated thimerosal exposure
      5. Contaminated seafood exposure (see below)
      6. Exposure to paint containing Mercury
    2. Effects vary by form of Mercury
      1. Elemental Mercury
        1. Exposure via inhalation, aspiration, or injection
        2. Causes lung toxicity and ARDS
        3. Can also cause neruologic and renal sequelae
      2. Inorganic Mercury salts
        1. Exposure via ingestion
        2. Results in gastrointestinal and nephrotoxicity
      3. Organic Mercury compounds
        1. Exposure via ingestion or transdermal
        2. Results in delayed neurotoxicity
    3. Mechanisms of injury
      1. Mercury binds sulfhydryl groups
      2. Nephrotoxicity
        1. Local immune reaction and direct damage
      3. Skin injury
        1. Local immune reaction
      4. Cardiovascular changes (Hypertension and tachycardia)
        1. Catechol-O-methyltransferase
      5. Neurotoxicity
        1. Injury to cerebellum, postcentral gyri, calcarine
  3. Symptoms and signs
    1. Inhalation injury (Mercury vapor)
      1. Acute exposure
        1. Shortness of Breath
        2. Fever and chills
        3. Acute Respiratory Distress Syndrome (ARDS)
        4. Bloody Diarrhea
        5. Renal tubular necrosis
      2. Subacute or chronic exposure
        1. Metal fume fever
        2. Neuropsychiatric changes
        3. Nephrotoxicity
        4. Skin changes
    2. Aspiration Injury (liquid Mercury)
      1. Tracheobronchial hemorrhage
      2. Aspiration pneumonitis
    3. Ingestion Injury (inorganic Mercury salts)
      1. Acute ingestion
        1. Corrosive Gastroenteritis
        2. Gastrointestinal Bleeding
        3. Mucous membrane grayish discoloration
        4. Hypovolemic shock (secondary to fluid shifts)
        5. Acute Tubular Necrosis
        6. Other gastrointestinal symptoms as below
      2. Chronic or subacute exposure
        1. Neurotoxicity
          1. NeurAsthenia, erethism
        2. Nephrotoxicity
          1. Proteinuria (Nephrotic Syndrome may result)
        3. Gastrointestinal injury
          1. Metallic Taste
          2. Gingivostomatitis
          3. Loose teeth
          4. Burning mouth sensation
          5. Hypersalivation
    4. Chronic ingestion of MethylMercury (organic Mercury)
      1. Delayed neurotoxicity
      2. Visual field constricted
      3. Ataxia
      4. Sensory deficit
      5. Tremor or spasticity
      6. Dysarthria
      7. Hearing Loss
      8. Hyperreflexia
  4. Labs
    1. Urine Mercury level
      1. Best correlates with Mercury Toxicity
      2. Acceptable urine levels <20 mcg/L
      3. Treatment required if urine Mercury >150 mcg/L
    2. Blood Mercury level
      1. Required to detect organic Mercury exposure
      2. Acceptable blood levels <10 mcg/L
      3. Treatment required if blood Mercury >35 mcg/L
  5. Radiology
    1. Injected metallic Mercury is radiopaque
  6. Management: Acute Exposure
    1. Mercury ingestion
      1. See Gastric Decontamination
      2. Gastric Lavage
        1. Use protein solutions (e.g. milk)
        2. Charcoal not useful (does not bind Mercury)
    2. Mercury Inhalation
      1. Supportive care
      2. Antibiotics not indicated
      3. Corticosteroids not indicated
    3. Mercury aspiration
      1. Airway Suctioning
      2. Postural drainage
    4. Mercury injection
      1. Surgical debridement
  7. Management: Chelating agents for acute-chronic exposure
    1. Indications
      1. See Labs above for urine and blood Mercury levels
    2. Agents
      1. Dimercaprol
        1. Indicated in inorganic Mercury Poisoning
        2. Contraindicated in organic, methylMercury Poisoning
      2. DMSA
        1. Preferred agent for acute and chronic poisoning
        2. Not FDA indicated
      3. D-Penicillamine
        1. Needs complete Gastric Decontamination before use
  8. Management: Environmental clean-up
    1. Precautions
      1. Do not use a vacuum (volatilizes Mercury)
      2. Dispose of contaminated absorbable surfaces
    2. Small spills (e.g. broken thermometer)
      1. Scoop onto stiff card
      2. Move Mercury into bag and seal bag
      3. Dispose of Mercury as hazardous waste
    3. Larger spills
      1. Sand or Mercury Decontamination kit
      2. Consider contacting HazMat
  9. Prevention: Precautions regarding dietary fish intake
    1. Avoid fish high in Mercury content
      1. Shark
      2. Swordfish
      3. King Mackerel
      4. Tilefish
    2. Limit fish with moderate Mercury content (6 oz/week)
      1. Albacore tuna
      2. Locally caught fish with unknown concentration
    3. Choose fish with lowest Mercury content
      1. Salmon
      2. Pollock
      3. Canned light tuna

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