A contaminant is something that contaminates a substance such as water or food.
例句
Contaminants found in poultry will also be found in their eggs...家禽身上發現的污染物，在禽蛋里也會有。We are exposed to an overwhelming number of chemical contaminants every day in our air, water and food.我們每天都會通過空氣、水和食品接觸到數量驚人的化學污染物。