Glycol, any of a class of organic compounds belonging to the alcohol family; in the molecule of a glycol, two hydroxyl (―OH) groups are attached to different carbon atoms. The term is often applied to the simplest member of the class, ethylene glycol. … Ethylene glycol and some of its derivatives are mildly toxic.

Ethylene glycol is a chemical commonly used in many commercial and industrial applications including antifreeze and coolant. Ethylene glycol helps keep your car’s engine from freezing in the winter and acts as a coolant to reduce overheating in the summer.