When food is irradiated, energy passes through the food like light through a window. The radiation levels used for food processing simply aren't high enough to contaminate food, and the food itself never touches the energy source. It's just one important tool for protecting food safety. Consumers still need to take appropriate precautions in handling their food - including washing hands and cleaning preparation surfaces often, separating foods to avoid cross contamination, cooking foods to a safe temperature and refrigerating and storing foods properly. Otherwise, potential disease-causing organisms can still multiply and cause problems.
Irradiation is used to sterilize medical products like syringes and surgical gloves.
It's also used to destroy bacteria in cosmetics, sterilize wine corks and purify wool. It's used on some tampons and sanitary napkins, pacifiers and contact lens solution. Irradiated foods have been available in a few American grocery stores for about 6 years. At least a dozen irradiated foods are now being sold - including chicken, fruits and spices. Irradiated spices do not need to be labeled if they are used as ingredients in other food products.