Arsenic toxicity

Background

• infamous historical poison
• heavy metal
• 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
• readily absorbed via GI tract and inhalation, poorly via skin
• 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

Clinical Features

1. Acute ingestion
   1. GI symptoms
   2. Pulmonary Edema
   3. Shock
   4. Rhabdomyolysis
   5. Seizure
   6. coma
   7. death
   8. cardiovascular instability
2. Arsine gas exposure
   1. hemolysis causing abdominal pain, hematuria, jaundice
3. Subacute or chronic poisoning
   1. Anemia
   2. sensory motor neuropathy
   3. skin changes
   4. ataxia
   5. CNS depression

Workup

• urine arsenic level (usual normal level is <50mcg/L); both urine spot test and 24h urine collection
• blood arsenic level not helpful (cleared within 2 hrs of exposure)
• ECG to eval for QT Prolongation in acute exposure
• CBC to eval for hemolysis
• BMP, Mg, phos, Ca, LFTs, CK, type and screen
• CXR if respiratory symptoms 

Treatment

• supportive care, ABCs, IV, O2, monitor
• removal from exposure
• NO Charcoal - 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 resp distress
• IV fluids
• CHELATION therapy: if severe symptoms present

1. Dimercaprol (BAL). 3-5 mg/kg IM Q4-6h

Disposition

• admit pt's with significant symptoms
• ED observation and discharge with follow-up for mildly symptomatic pts

See Also

• Toxicology (Main)
• Heavy Metals

Sources

Harwood-Nuss, EMedicine