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U.S. Department of Health and Human Services


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List of Terms: I

Return to Comprehensive List of Terms


> Incidence 
The number of new cases of foodborne illness in a given population during a specified period of time. For example, the number of new cases per 100,000 people per year.


> Infection
Attachment and growth of pathogenic micro-organisms, including bacteria, protozoans, viruses, and parasites, on or within the body of a human or animal.


> Inspection (see Food Inspection)


> Intoxication
A condition in which the body is poisoned by a toxin. The substance can disrupt the functioning of the intestinal cells or can be absorbed into the blood and carried to parts of the body. Intoxication caused by bacterial toxins usually results in headache, dizziness, vomiting, and stomach pains.

Is irradiated food safe to eat?

Food cannot be irradiated unless the Food and Drug Administration (FDA) approves it. The FDA has evaluated irradiation safety for more than 40 years and found the process safe and effective for many foods. Health experts also say that in addition to reducing E. coli O157:H7 contamination, irradiation can help control the potentially harmful bacteria Salmonella and Campylobacter, 2 chief causes of foodborne illness.

Irradiation does not make food radioactive, compromise nutritional quality, or noticeably change the taste, texture, or appearance of food, as long as it's applied properly to a suitable product. It's important to note that irradiation cannot be used with all foods. For example, it causes undesirable flavor changes in dairy products and it causes tissue softening in some fruits, such as peaches and nectarines.

The Radura
The Radura is the international
symbol for irradiation.

How will I know if food has been irradiated?

As part of its approval, FDA requires that irradiated foods include labeling with either the statement treated with radiation or treated by irradiation, along with the international symbol for irradiation, the Radura (see photo above.) Irradiation labeling requirements apply only to foods sold in stores. For example, irradiated spices or fresh strawberries should be labeled. Irradiation labeling does not apply to restaurant foods.


> Irradiation
A process in which ionizing energy is used to kill pathogens and other harmful substances in food by causing breaks in the cell's deoxyribonucleic acid (DNA).

Food Safety Implication: Food irradiation is a technology, like heating, that can destroy harmful bacteria in raw foods. Irradiation complements, but does not replace the need for proper food preparation, storage, and distribution practices by producers, processors, and consumers.

How It Works: An intense pulse of energy is emitted, either from a gamma radiation source like Cobalt 60 or from an electrical source like an electron beam accelerator. The energy penetrates the food and destroys any bacteria.

Four Main Purposes of Food Irradiation:

  1. Preservation - Irradiation can be used to destroy or inactivate organisms that cause spoilage and decomposition, thereby extending the shelf life of foods.
  2. Sterilization - Foods that are sterilized by irradiation can be stored for years without refrigeration. Sterilized food is useful in hospitals for patients with severely-impaired immune systems, such as AIDS patients or people undergoing chemo-therapy. Irradiated foods can also be used by the military and for space flights.
  3. Control Sprouting, Ripening, and Insect Damage - Irradiation offers an alternative to chemicals for use with potatoes, tropical and citrus fruits, grains, spices, and seasonings. However, since no residue is left in the food, irradiation does not protect against reinfestation as insect sprays and fumigants do.
  4. Control Foodborne Illness - Irradiation can be used to effectively eliminate pathogens that cause foodborne illness, such as Salmonella.

Food Irradiation Timeline

1920s: French scientists discover that irradiation preserves foods.

1963: Irradiation is approved by the Food and Drug Administration (FDA) to control insects in wheat and wheat powder. Although irradiation was not used in the United States at this time, 400,000 tons of wheat per year were irradiated in the Ukraine to kill insects.

1964: This is the first time irradiation was used in the United States. The FDA approves irradiation to extend the shelf life of white potatoes.

An Astronaut

1970s: The National Aeronautics and Space Administration (NASA) adopts irradiation to sterilize meat for astronauts to eat in space. Irradiation is still used by NASA today.

1997: Red meat is approved for irradiation by the FDA.

2000: The U.S. Department of Agriculture's Food Safety and Inspection Service (FSIS) approves the irradiation of beef. Shell eggs and seeds for growing sprouts are approved for irradiation by the FDA.

2005: Molluscan shellfish is approved for irradiation by the FDA, making it the most recent food to be approved. Irradiation is used to control pathogens, such as Vibrio species and other foodborne pathogens in fresh or frozen molluscan shellfish (e.g., oysters, mussels, and clams).


> Isolate (see Food Isolate)