To prevent food adulteration, any poisonous or dangerous substances must be prevented from contaminating foods or the containers in which food is stored. Adulterants include poisons, chemicals and the dangerous pathogen E. coli.
Food workers employ numerous safeguards to prevent food adulteration, such as testing samples of food prior to making it available for human consumption. Food must be inspected to ensure it does not contain any objectionable material, such as the stem left on the leaf of a plant or mold on a piece of fruit. The United States Food and Drug Administration has established limits for the foreign material that a food item can contain without violating the law. These limits are called action or tolerance levels.
Additionally, food adulteration includes "food fraud," which is passing off a food item as something else, such as serving horse meat instead of beef. U.S. laws impose harsh penalties for anyone found to have engaged in food fraud.