Arsenic

Aka: Arsenic, Arsenic Poisoning, Arsenic Toxicity

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II. Pathophysiology

  1. Arsenic is a metalloid element (atomic number 33)
    1. Similar chemical properties to Phosphorus
    2. Although highly toxic in its inorganic salt states, it is nonpoisonous in gray, elemental state
    3. Found throughout earth's crust and in mined ores (esp. as sulfide) or combined with other metals (e.g. iron)
  2. Mechanism of toxicity
    1. Arsenic blocks cellular respiration (Oxidative Phosphorylation) and Gluconeogenesis at multiple pathway sites
      1. Inhibits pyruvate dehydrogenase
    2. Arsenic affects glutathione metabolism leading to Hemolysis and Anemia
      1. Inhibits glutathione synthetase and G6PD
    3. Arsenic inhibits cardiac Potassium channels
      1. Dysrhythmia risk
  3. Arsenic has a Garlic-like odor when ingested
  4. Arsenic Ingestion (or less commonly by skin absorption or inhalation)
    1. Acute large ingestions
      1. Insect poisons (Pesticides)
      2. Manufacturing (Ceramics, semiconductors)
    2. Chronic exposures
      1. Contaminated water
      2. Produce grown in contaminated soil (e.g. rice)
      3. Low organic levels are found in fish, crustaceans and algae
  5. Medical uses
    1. Acute promyelocytic Leukemia (Arsenic Trioxide or ATO)
    2. African Trypanosomiasis (Melarsoprol)
    3. Veterinary antihelminth (Thiacetarsamide)

III. Pharmacokinetics

  1. Gastrointestinal absorption is rapid
  2. Inorganic forms (trivalent, pentavalent) are more toxic than organic forms
  3. Lethal dose
    1. Child: >2 mg/kg
    2. Adult: >120 to 200 mg

IV. Findings: Acute Poisoning

  1. Gastrointestinal Symptoms (within minutes to hours of ingestion)
    1. Nausea or Vomiting
    2. Abdominal Pain
    3. Watery Diarrhea (rice-water)
  2. Cardiopulmonary symptoms and signs
    1. Hypotension to Cardiovascular collapse
    2. Tachycardia
    3. Acute Respiratory Distress Syndrome (ARDS)
    4. QTc Prolongation
    5. Dysrhythmia
    6. Paradoxically low Systemic Vascular Resistance (Vasoplegia)
    7. Systemic Inflammatory Response Syndrome (SIRS)
  3. Neurologic Symptoms
    1. Headache
    2. Vertigo
    3. Fatigue
    4. Encephalopathy with Delirium
    5. Peripheral Neuropathy (motor and sensory) is delayed
      1. Paresthesia
      2. Paralysis
  4. Skin
    1. Skin irritation
    2. Mucosal burning Sensation
    3. Erythroderma
    4. Desquamation
  5. Miscellaneous
    1. Acute Renal Failure
    2. Rhabdomyolysis
    3. Acute Hepatitis

V. Findings: Chronic Poisoning

  1. Mottled brown skin
  2. Hyperkeratosis of palms and soles
  3. Cutis edema
  4. Transverse striate Leukonychia
  5. Perforation of nasal septum
  6. Eyelid Edema
  7. Coryza
  8. Limb paralysis
  9. Reduced Deep Tendon Reflexes
  10. Carcinogenic with chronic exposure

VI. Labs

  1. See Unknown Ingestion
  2. Creatine Phosphokinase
  3. Comprehensive metabolic panel
  4. Complete Blood Count and Peripheral Smear
    1. Macrocytic Anemia
  5. Urinalysis
    1. Oliguria
    2. Hematuria
    3. Hemoglobinuria
  6. Arsenic Concentration
    1. Urine Arsenic (24 hour level)
      1. Abnormal if >100 mcg total (or 50 mcg/L, >100 mcg/g Creatinine)
      2. May also be positive with seafood ingestion
  7. Tissue Exam reveals Arsenic deposits
    1. Urine
    2. Nails
    3. Hair

VII. Diagnostics

  1. Electrocardiogram
    1. QTc Prolongation

VIII. Imaging

  1. Abdominal XRay
    1. Arsenic is radiopaque

IX. Management

  1. See Unknown Ingestion
  2. Consult poison control
  3. Supportive care
    1. ABC Management
    2. Intravenous Fluids
  4. Gastric Lavage and Whole Bowel Irrigation indications
    1. Abdominal XRay positive for radiopaque Arsenic
  5. Chelation
    1. Severe acute Arsenic Toxicity
      1. Dimercaprol (British Anti-Lewisite or BAL) 4 mg/kg IM every 4 hours
    2. Chronic Arsenic Toxicity or less severe acute toxicity
      1. Dimercaptosuccinic acid (succimer) 10 mg/kg orally every 8 hours for 5 days
  6. Disposition
    1. Admit symptomatic patients (more than isolated gastrointestinal symptoms) to ICU
    2. May typically discharge if no gastrointestinal signs or symptoms at 6-12 hours after ingestion
  7. Other measures
    1. Hemodialysis is NOT typically effective

X. References

  1. Carroll (2026) Crit Dec Emerg Med 40(1): 34
  2. Kinker and Glauser (2021) Crit Dec Emerg Med 35(9): 19-27
  3. Tomaszewski (2022) Crit Dec Emerg Med 37(1): 32

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