pollutant (n.)

late 14c., polluten, "to defile, violate the sanctity of, render ceremonially unclean," a back formation from pollution, or else from Latin pollutus, past participle of polluere "to defile, pollute, contaminate." Related: Polluted; polluting. Meaning "make physically foul" is from 1540s; specific sense "contaminate the environment" emerged by 1860, but was not yet in the 1895 Century Dictionary.

agent or instrumental suffix, from Old French and French -ant, from Latin -antem, accusative of -ans, present-participle suffix of many Latin verbs. Compare -ance.