Arsenic Poisoning

Basics

Description

  • Acute toxicity:
    • Caused by intentional ingestion, malicious poisoning, or medication error
  • Minimal lethal ingested dose ∼2 mg/kg
  • Chronic toxicity:
    • Resulting from occupational exposures, water or food contamination, or use of folk remedies containing arsenic
  • Ingestion is the primary route of exposure
  • Inhalational toxicity is possible from arsine gas exposure

Etiology

  • Most cases seen in the ED result from intentional ingestion or malicious poisoning of inorganic arsenic salts
  • Sodium arsenate, sold as ant killer in the past, is now very uncommon in the US
  • Contaminated food and water supplies are the most common cause worldwide
  • Inorganic arsenic trioxide is approved as a chemotherapeutic agent for acute myelogenous leukemia (AML)
  • Melarsoprol, an organic arsenical, has been used to treat trypanosomiasis since 1949
  • Found in pesticides, older industrial wood preservatives (phased out in 2003)
  • Ayurvedic medicines, folk remedies (herbal balls), and other traditional/cultural medicines can contain arsenic
  • May be released as arsine gas from combustion of zinc- and arsenic-containing compounds

Mechanism

  • Arsenic exists in several forms – gas (arsine, or lewisite), organic, elemental, and inorganic
  • Inorganic forms (pentavalent and trivalent arsenic) are most frequently involved in toxic exposures:
    • Pentavalent arsenic uncouples oxidative phosphorylation
    • Most pentavalent arsenic is converted to the more toxic trivalent arsenic in the body
    • Trivalent arsenic binds sulfhydryl groups and interferes in hemoglobin production
    • Some trivalent arsenic may be methylated into species of varying toxicity
    • The more reactive species are DNA damaging and genotoxic

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