Arsenic toxicity

Background

  • Heavy metal
  • Readily absorbed via GI tract and inhalation, poorly via skin
  • Tasteless and odorless
  • Organic trioxide form used as chemotherapeutic agent
  • Trivalent form, As3+, is toxic to over 200 intracellular enzymes
  • Known carcinogen: skin, lung, other
  • Ingestion fatal dose: 100-200mg

Sources of Exposure

  • Poisoning
  • Contaminated drinking water
  • Eruptions
  • Metal and semiconductor industry
  • Wood preservatives
  • seafood arsenic (felt to be organic form which is NONTOXIC and cleared from body in few days)

Clinical Features

Typical rash associated with chronic exposure

Acute ingestion

"Mees lines"

Arsine gas exposure

Subacute or chronic poisoning

Differential Diagnosis

Heavy metal toxicity

Acute diarrhea

Infectious

Noninfectious

Watery Diarrhea

Traveler's Diarrhea

Evaluation

Workup

  • Urine arsenic level
  • ECG to eval for QT Prolongation in acute exposure
  • CBC and retic count, expect hemolytic anemia
  • BMP, Mg, Phos, Ca, LFTs, CK
  • Type and screen for possible transfusion in arsine gas exposure
  • CXR if respiratory symptoms 
  • Consider other ingestion labs including acetaminophen and salicylate level in intentional ingestions

Diagnosis

  • Urine arsenic level (usual normal level is <50mcg/L); both urine spot test and 24h urine collection
    • Lab must differentiate inorganic from organic arsenic (treat for inorganic exposure only)
  • Blood arsenic level not helpful (cleared within 2 hrs of exposure)

Management

  • Supportive care, ABCs, IV, O2, monitor
  • Removal from exposure
  • NO Charcoal if co-ingestion is not suspected - adsorbs poorly to arsenic
  • Consider Whole Bowel Irrigation if large radiopaque material in GI tract on xray
  • Airway management and mechanical ventilation if acute inhalation of arsine gas and respiratory distress
  • IV fluids
  • CHELATION therapy: if severe symptoms present
  • Dimercaprol (BAL). 3-5mg/kg IM Q4-6h

Disposition

Admission

  • Admit patient to intensive care setting if symptomatic from acute exposure

Discharge

  • Asymptomatic/mildly symptomatic patients or those with suspected chronic exposures may be discharged w/ outpatient follow-up after initial ED observation.

See Also

References

  1. Marx et al. “Cholera and Gastroenteritis caused by Noncholera Vibrio Species”. Rosen’s Emergency Medicine 8th edition vol 1 pg 1245-1246.