Possible Clues:

• Chem. pollutant banned in 1979
• Banned chemical
• Outlawed pollutant, for short
• Toxic pollutant, for short
• Chem. source of the Hudson's River's Superfund site status
• Toxic chem.
• Toxic pollutant banned since the 1970s
• Toxic chemical, for short
• Chem. contaminant banned by the U.S. in 1979
• Pollutant banned in the U.S. in 1979