Ethylene Glycol is a colorless, odorless, sweet-tasting chemical commonly used as an antifreeze in automotive applications and as a raw material in the production of polyester fibers. Despite its utility, it is highly toxic and poses significant health risks if ingested, inhaled, or absorbed through the skin.
Poisoning typically occurs through accidental ingestion, often due to its sweet taste, which can attract children and animals. It can also be ingested intentionally in cases of self-harm. Inhalation of vapors or dermal exposure are less common but still possible routes of exposure.
Metabolism and Mechanism of Toxicity
Once ingested, Ethylene Glycol is metabolized in the liver by alcohol dehydrogenase to various toxic metabolites, including glycolic acid, glyoxylic acid, and ultimately, oxalic acid. These metabolites are primarily responsible for the toxic effects, causing metabolic acidosis and crystal formation in organs such as the kidneys.
Clinical Symptoms of Ethylene Glycol Poisoning
Symptoms progress through three stages:
1. Neurological Phase (0.5 to 12 hours post-ingestion): Symptoms include intoxication, nausea, vomiting, and central nervous system depression.
2. Cardiopulmonary Phase (12 to 24 hours post-ingestion): This phase is characterized by tachycardia, hypertension, and possibly pulmonary edema.
3. Renal Phase (24 to 72 hours post-ingestion): Acute kidney injury occurs due to oxalate crystal deposition, leading to oliguria or anuria and potentially renal failure.
Diagnosis
Early diagnosis is critical. It is based on patient history, clinical symptoms, and laboratory tests. Key diagnostic indicators include an elevated anion gap metabolic acidosis, presence of urinary oxalate crystals, and elevated serum levels of ethylene glycol.
Treatment
Immediate medical intervention is essential for a favorable outcome. Treatment options include:
1. Fomepizole or Ethanol: Both inhibit the enzyme alcohol dehydrogenase, preventing the formation of toxic metabolites.
2. Hemodialysis: Effective in removing ethylene glycol and its metabolites from the bloodstream.
3. Supportive Care: This includes intravenous fluids, correction of acidosis with bicarbonate, and monitoring of renal function.
Prognosis
The prognosis depends on the amount ingested, the time to treatment, and the effectiveness of the intervention. Early and aggressive treatment significantly improves the chances of recovery, although delayed treatment may result in long-term complications or death.
Prevention
Preventive measures include proper storage and labeling of products containing ethylene glycol, use of less toxic alternatives like propylene glycol in antifreeze, and public education on the dangers of this chemical.
Regulatory and Safety Measures
Various regulatory agencies have guidelines and safety measures in place to minimize the risk of ethylene glycol poisoning. These include requirements for bittering agents in antifreeze formulations to deter accidental ingestion and strict labeling requirements.
