The government's food-safety rules require chicken processors to identify "critical control points" where contamination might occur, then establish procedures for preventing, eliminating, or reducing those hazards. As our tests show, nothing guarantees a clean chicken. The contamination rate can vary with what the birds are fed, the preventive measures used, growing conditions, and the time of year, says Michael Doyle, Ph.D., director of the University of Georgia's Center for Food Safety. The procedures differ among plants; those outlined here are a possible scenario.
Some chicks are contaminated with salmonella from their mothers or their own shells during hatching. Others ingest bacteria from their surroundings. Live birds infected with campylobacter or salmonella usually show no symptoms. To reduce the risk to people, some companies vaccinate hens and chicks against salmonella.
Usually a new flock of thousands of chicks is trucked to a house run by a farmer according to the poultry producer's specifications. Chickens habitually peck the ground, ingesting bacteria from litter and feces, and could be exposed to vermin. Companies try to keep germ carriers away and continuously monitor the flocks' general health. Antibiotics are used to prevent or treat illness and might also be given to speed chickens' growth. But treated birds can't be sold as USDA-certified organic.
Chickens travel to the processing plant in cages. Filth can spread.
Companies take steps to ensure their packaged chickens are properly refrigerated during shipping and delivery to market. Federal regulations require transport at a temperature no higher than 40° F.
Improper temperature or handling can introduce bacteria or cause them to multiply.
Cooking chicken thoroughly, to at least 165° F, and washing anything that comes in contact with raw chicken greatly reduces risk.