Exposure to the skin and lungs may cause irritation but does not cause the systemic toxicity in the way that methanol does. Lethal quantities in adults are considered to be 100 ml, but in children much less may cause serious cardiac, renal, and CNS toxicity. Ethylene glycol itself is relatively nontoxic. After absorption the unchanged compound undergoes glomerular filtration and passive reabsorption. It is then broken down into metabolites that are highly toxic and cause the associated findings of ethylene glycol toxicity.
Ethylene glycol is converted to glycoaldehyde by alcohol dehydrogenase.
I Oxalate These metabolites inhibit oxidative phosphorylation, sulfhydrl-containing enzymes, and protein synthesis. Glycolic acid is the major cause of the metabolic acidosis that is seen in ethylene glycol toxicity, although glyoxylic acid also may contribute. Toxicity from ethylene glycol is produced from the above metabolites and the fact that they cause a severe acidosis, as well as from the fact that oxalate precipitates with calcium to produce widespread tissue injury in the kidney, brain, liver, blood vessels, and pericardium. Hypocalcemia may also result. At this phase, the patient may appear intoxicated with nausea, vomiting, ataxia, absent reflexes, nystagmus, and myoclonic jerks but has no smell of alcohol.