Pennsylvania and Illinois Trichloroethylene has someone uses which are common to man's everyday activities such as removing greasy stains and substances from metal surfaces and clothes. Also, it's odorless and sometimes blue and colorless nature makes it easily to apply to situations that require it's uses. However, it posse some health risk especially if it is detected to be in water. It is common in those states probably because they use it to remove grease from their water supplies.