The birthplace of IBM, Endicott, suffered pollution for decades, however. IBM used liquid cleaning agents in circuit board assembly operation for more than two decades, and six spills and leaks were recorded, including one leak in 1979 of 4,100 gallons from an underground tank. These left behind volatile organic compounds in the town's soil and aquifer. Traces of volatile organic compounds have been identified in Endicott’s drinking water, but the levels are within regulatory limits. Also, from 1980, IBM has pumped out 78,000 gallons of chemicals, including trichloroethane, freon, benzene and perchloroethene to the air and allegedly caused several cancer cases among the townspeople. IBM Endicott has been identified by the Department of Environmental Conservation as the major source of pollution, though traces of contaminants from a local dry cleaner and other polluters were also found. Remediation and testing are ongoing, however according to city officials, tests show that the water is safe to drink.
What was a local dry cleaner found to be the main source of in 1979?