any materials unused and rejected as worthless or unwanted

make impure

an insecticide that is also toxic to animals and humans; banned in the United States since 1972

a fluorocarbon with chlorine; formerly used as a refrigerant and as a propellant in aerosol cans

a compound in which the hydrogen atoms of a hydrocarbon have been replaced by bromine and other halogen atoms; very stable; used in fire extinguishers although it is thought to release bromine that depletes the ozone layer

any of several oxides of nitrogen formed by the action of nitric acid on oxidizable materials; present in car exhausts

a colorless toxic gas (SO2) that occurs in the gases from volcanoes; used in many manufacturing processes and present in industrial emissions; causes acid rain