Raw hamburger may contain harmful bacteria that can produce food-borne illness such as Escherichia coli O157:H7, due to the occasional initial improper preparation of the meat, so caution is needed during handling and cooking. Because of the potential for food-borne illness, the USDA recommends hamburgers be cooked to an internal temperature of 160 °F (71 °C).[32] If cooked to this temperature, they are considered well-done.[33]