Coolant, also known as antifreeze, is a toxic liquid that contains ethylene glycol, propylene glycol, and methanol. These chemicals are added to the coolant to prevent the engine from freezing or overheating. However, they can be harmful if ingested, inhaled, or if they come in contact with your skin. Ethylene glycol is particularly dangerous as it can cause kidney damage, seizures, and even death if consumed in large amounts.