Arsenic Poisoning

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
• Sodium arsenate, found in ant killer, is the most common acute exposure in the US
• Contaminated food and water supplies are the most common cause worldwide
• Inorganic arsenic trioxide has been recently 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, certain folk remedies (herbal balls), industrial wood preservatives
• May be released as arsine gas from combustion of zinc- and arsenic-containing compounds

• 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