What are the health risks of inhaling steam from antifreeze (ethylene glycol and propylene glycol)?

Health Risks of Inhaling Steam from Antifreeze

Inhaling steam from antifreeze containing ethylene glycol poses significant health risks including metabolic acidosis, neurotoxicity, kidney injury, and potential death, and should be considered a medical emergency requiring immediate healthcare attention. 1

Composition and Toxicity Mechanisms

Antifreeze products typically contain either:

• Ethylene glycol (EG): The more toxic component
• Propylene glycol (PG): Generally less toxic alternative

When heated and inhaled as steam, these compounds can enter the body through the respiratory system, with several concerning effects:

Ethylene Glycol Toxicity

• EG itself has minimal toxicity, but its metabolites cause severe damage 1
• Metabolized by alcohol dehydrogenase to:
  • Glycoaldehyde
  • Glycolate
  • Glyoxylate
  • Oxalate
• These metabolites cause:
  • Severe metabolic acidosis
  • Central nervous system damage
  • Pulmonary injury
  • Kidney damage and potential failure 2, 3

Additional Toxic Components

• Some antifreeze products contain other chemicals that can:
  • Act as oxidizing agents
  • Potentially cause methemoglobinemia (reduced oxygen-carrying capacity of blood) 4
• Humectants like propylene glycol, when inhaled, have been shown in animal studies to:
  • Increase lung viral titers
  • Downregulate innate immunity
  • Disrupt immune homeostasis 1

Clinical Manifestations

Inhalation of antifreeze steam can lead to a progression of symptoms:

1. Early symptoms (similar to ethanol intoxication):

   • Inebriation
   • Ataxia (loss of coordination)

2. As metabolites form (3-6 hours after exposure):

   • Metabolic acidosis develops
   • Anion gap increases (>10-12 mEq/L) 1
   • Osmolar gap increases

3. Severe manifestations:

   • Progressive neurotoxicity (confusion, seizures, coma)
   • Cardiopulmonary complications
   • Acute kidney injury
   • Calcium oxalate crystal formation in tissues 1

Diagnostic Indicators

If exposure to antifreeze steam is suspected, important diagnostic markers include:

• Elevated anion gap (>23 mmol/L indicates significant toxicity) 1
• Increased osmolar gap
• Presence of calcium oxalate crystals in urine
• Metabolic acidosis
• Dark brown blood (if methemoglobinemia develops) 4

Treatment Approach

For significant exposure to antifreeze steam requiring medical attention:

1. Immediate stabilization:

   • Removal from exposure source
   • Supplemental oxygen if needed
   • Supportive care

2. Antidotal therapy (for significant systemic absorption):

   • Fomepizole (preferred) or ethanol to block alcohol dehydrogenase
   • Methylene blue if methemoglobinemia develops 4

3. Extracorporeal treatment (ECTR) indications:

   • Severe metabolic acidosis (anion gap >27 mmol/L)
   • Kidney impairment
   • Coma or seizures
   • High ethylene glycol concentration (if measurable) 1

Prevention and Safety Precautions

• Avoid heating antifreeze or being near heated antifreeze
• Ensure proper ventilation when working with antifreeze products
• Consider using propylene glycol-based products instead of ethylene glycol when possible, as PG has significantly lower toxicity 5
• Store antifreeze products securely to prevent accidental exposure

Special Considerations

• Ethylene glycol has a sweet taste, which may lead to accidental ingestion, but its vapors can also be inhaled when heated 2
• The combination of inhalation and potential dermal absorption increases risk of systemic toxicity
• Individuals with pre-existing kidney or liver disease may be at higher risk for complications

The severity of toxicity from inhaling antifreeze steam depends on concentration, duration of exposure, and individual factors, but should always be treated as potentially serious given the life-threatening complications associated with ethylene glycol poisoning.