Ethylene glycol is a poison that causes about fifty deaths a year in the United States. Treating people who have drunk ethylene glycol with massive doses of ethanol can save their lives.
Suggest a reason for the effect of ethanol.
Now look up the structure for ethanol:
The two are very similar. Ethylene glycol is dangerous because the body metabolizes (digests, essentially) it into something far more dangerous: glycolic acid. You can then hypothesize that increasing the concentration of ethanol will “flush out” the ethylene glycol before it gets metabolized. A poisoned person’s body will focus on metabolizing the ethanol, rather than the ethylene glycol, allowing the poison more time to get out of the body (through sweat, urine, etc.). The similarities in the compounds’ structures mean they are likely broken down in the same way, or by the same enzyme. Using up all the enzyme before it can attack the glycol can stop the production of the dangerous glycolic acid.
If you’re still stuck, look up “antifreeze poisoning”, since this is what ethylene gylcol is used in. You can also look up “methanol poisoning”, a problem which is also treated by large quantities of ethanol, for the same reasons.