"For decades, one of the nation's most widely used dry cleaning solvents was billed as a marvel of modern chemistry that could safely remove dirt and stains from clothing.
Shops sprang up to take advantage of the chemical, perchloroethylene, also known as PCE or perc. People became familiar with the sharp odor of clothes freshly removed from plastic wrap, a sign that perc was used to clean them.
But over the years, with little if any notice to the public, the often sloppy use of perchloroethylene has poisoned hundreds of sites in Illinois. As scientists linked perc exposure to cancer, liver damage, neurological problems and other ailments, regulators found problems in virtually every town with a dry cleaner.
The Illinois Environmental Protection Agency has signed off on cleanups of about 500 sites since the late 1990s. More than 400 polluted locations remain, though few neighbors may know it. Most are in Chicago and its suburbs."