An odd way to be haunted by an old patent?

A patent on p-chlorobenzenesulfonic acid has been discussed in an odd situation. Low levels of it appeared in test results from three St. Louis city water wells and someone noticed that Michigan Chemical Company, headquartered in St. Louis, had a patent on separating it. St. Louis City Councilman Bill Schrum was unaware of the Michigan Chemical patent. Schrum had worked at the plant, but not on the chemical end. He then went on to work for Dow Chemical in Midland as a chemical lab technician. "They knew they had a large quantity of this material," Schrum said. "The patent might answer a few questions. It looks like this compound has been leaking into our aquifer ever since and who knows what else it's carrying with it."