Most antifreeze is made from ethylene glycol, but it can contain other chemicals or ingredients, such as propylene glycol, ethanol, methanol and isopropyl alcohol. Some modern types of antifreeze include chemicals that allow them to last twice as long as conventional fluids, while other antifreeze types use propylene glycol as the main ingredient, resulting in a product that is much safer for pets and humans.
The waste created from antifreeze is toxic to animals and humans, and it is harmful to the environment because it contains heavy metals, such as chromium, cadmium and lead. Antifreeze is primarily used in the cooling systems of automobiles that have internal combustion engines. It is also used in commercial refrigeration systems.