Windshield washer fluid is made from a poisonous alcohol called methanol as well as ethylene glycol.
Up to 99% isopropyl alcohol is also added to the windshield washer fluid in cold climates during the winter to keep the windshield washer fluid from freezing.
You can also add rubbing alcohol or even high proof Vodka to windshield washer fluid to keep it from freezing if you don't have the type of washer fluid that doesn't freeze.