Answer: Antifreeze

Ethylene glycol is the primary ingredient in automotive antifreeze and a cause of accidental poisoning in children and household pets due to its sweet taste. The source of the toxicity isn’t necessarily the compound itself, but the metabolites thereof. In the body, ethylene glycol starts off by producing neurological and gastrointestinal symptoms (similar to alcohol poisoning), but then shifts to problems such as hyperventilation, metabolic acidosis, cardiovascular dysfunction, and eventual kidney failure as it is broken down into glycolic and oxalic acids.

Fortunately, if the patient is treated quickly enough treatment is usually successful and the patient almost always makes a full recovery. The two primary treatments used in ethylene glycol poisoning cases are fomepizole and ethanol (as in grain alcohol). Both treatments work on the same principle: both compounds compete with the ethylene glycol for alcohol dehydrogenase (an enzyme required for the metabolization of ethylene glycol and ethanol). Because ethanol has a higher affinity for the enzyme than ethylene glycol (by a magnitude of roughly 100 times), the ethanol quickly binds with all the available enzyme and the ethylene glycol is blocked from breaking down into glycoaldehyde, which prevents further degradation into highly toxic glycolic acid and oxalic acid.