Irradiated Food

Definition

Irradiated foods are foods that have been exposed to a radiant energy source to kill harmful bacteria, insects, or parasites, or to delay spoilage, sprouting, or ripening.

Foods permitted to be irradiated under FDA regulations (21 CFR 179.26)

Food

Purpose

Dose

Fresh, non-heated processed pork

Control of Trichinella spiralis

0.3 kGy min. to 1 kGy max.

Fresh foods

Growth and maturation inhibition

1 kGy max.

Foods

Arthropod disinfection

1 kGy max.

Dry or dehydrated enzyme preparations

Microbial disinfection

10 kGy max.

Dry or dehydrated spices/seasonings

Microbial disinfection

30 kGy max.

Fresh or frozen, uncooked poultry products

Pathogen control

3 kGy max.

Frozen packaged meats (solely NASA)

Sterilization

44 kGy min.

Refrigerated uncooked meat products

Pathogen control

4.5 kGy max.

Frozen uncooked meat products

Pathogen control

7 kGy max.

Fresh shell eggs

Control of Salmonella

3.0 kGy max.

Seeds for sprouting

Control of microbial pathogens

8.0 kGy max.

Fresh or frozen molluscan shellfish

Control of Vibrio species and other foodborne pathogens

5.5 kGy max.

Fresh iceberg lettuce and fresh spinach

Control of food-borne pathogens, and extension of shelf-life

4.0 kGy max.

kGy = kiloGray

SOURCE: U.S. Food and Drug Administration. Department of Health and Human Services. “21 CFR 179.26.” Code of Federal Regulations, title 21 (April 1, 2001): Sec. 179.26, Ionizing radiation for the treatment of food. https://www.gpo.gov/fdsys/granule/CFR-2002-title21-vol3/CFR-2002-title21-vol3-sec179-26 (accessed April 3, 2018).

Purpose

There are many reasons that foods are irradiated. The most common reason is for increased food safety. The Centers for Disease Control (CDC) estimates that there are about 76 million cases of foodborne illness each year in the United States, resulting in about 5,000 deaths annually. Irradiating foods can reduce the risk of many foodborne illnesses by killing the bacteria or pathogens responsible, or harming them to such an extent that they are not able to reproduce or cause disease. The National Aeronautics and Space Administration (NASA) exposes the food that astronauts eat while in space to a level of irradiation far higher than that approved for commercial use in order to reduce the risk that astronauts will develop illness while in space. Patients who have diseases that severely impair the functioning of the immune system are often fed irradiated foods to decrease the risk that they will develop a serious disease.

Irradiation can also be used to destroy insects and other pests that may be present on produce. When produce is shipped from Hawaii to the mainland United States, it must be fumigated to kill any insects or insect eggs that might be present so that they do not spread to the mainland. Irradiating this produce is sometimes used as an alternative to fumigation, as it does not leave a residue of chemicals on the produce in the way that fumigation can.

Some fruits and vegetables can be kept fresh longer by the use of low to moderate levels of irradiation. When exposed to low levels of radiation, potatoes, onions, and other vegetables do not sprout as quickly.

Strawberries and other berries can benefit from irradiation as well, as irradiation can significantly delay the growth of mold. Strawberries stay fresh from 3–5 days when they are not irradiated or treated in any way, but can stay fresh and unspoiled for up to three weeks after being irradiated.




Peaches, some irradiated, not showing rot after two weeks.





Peaches, some irradiated, not showing rot after two weeks.
(Ted Foxx/Alamy Stock Photo)

Description

Irradiated foods are foods that have been exposed to ionizing radiation. Ions are electrically charged particles, and ionizing radiation is radiation that produces these charged particles. Nonionizing radiation is produced by microwaves, television and radio waves, and visible light. Ionizing radiation is higher in power than these types of radiation, although it is in the same spectrum. The kinds of ionizing radiation used for food irradiation include gamma rays, beams of highenergy electrons, and x-rays.

When foods are irradiated, they are exposed to the source of the ionizing radiation for a short time. This radiation produces short-lived compounds that damage the deoxyribonucleic acid (DNA) of living organisms, such as bacteria that are in the food. Because DNA makes up the genes that contain the instructions that tell an organism how to grow and reproduce, once the DNA is damaged the organism cannot do this correctly and will die.

The amount of radiation required to irradiate foods depends on the type and thickness of the food product and the types of organisms that are present. Generally, the larger the DNA of the organism, the less radiation is required to irradiate it. Insects and parasites have larger DNA and require the lowest levels of radiation, whereas bacteria require slightly more, and viruses have very small amounts of DNA and require very high levels of radiation. Most parasites, insects, and bacteria can be eliminated at levels of radiation approved for commercial use, but many viruses cannot.

Irradiating foods does not make the foods radioactive in any way. Irradiation done using beams of high-energy electrons or x-rays does not even use any radioactive material. Irradiation done using gamma rays involves exposure of the food to a radioactive substance, usually cobalt 60 or cesium 137, for a short period. The radioactivity of this substance is not in any way transferred to the food that is exposed to it.

Precautions

Irradiation is not a substitute for safe food handling practices. Although irradiation kills or disables many pathogenic organisms, these organisms can be reintroduced to the foods if cross contamination occurs. In addition, not every pathogen is completely destroyed by irradiation, and leaving foods such as raw meat out at room temperature can allow these pathogens to reproduce to significant levels. Irradiation should be viewed as an extra step to help ensure that the food supply is safe, not as a replacement for food safety practices that are already in place.

Interactions

Irradiated foods are not expected to interact with any other foods, medicines, or products.

Complications

There are no complications expected from consuming irradiated foods. Some concerned groups have expressed fears that the long-term effects of eating irradiated foods are unknown. However, many different scientific studies have examined the effects on both animals and humans of consuming irradiated foods. There has not been any evidence that irradiated foods are harmful in either the short or long term. One study even examined many generations of animals fed irradiated foods and found no harmful effects. Irradiating food is accepted as a safe practice and is endorsed by many organizations, including the World Health Organization, the CDC, the U.S. Food and Drug Administration (FDA), and the American Medical Association.

Parental concerns

KEY TERMS
Ion—
An electrically charged particle.
Ionizing radiation—
Radiation that produces ions. Pathogen—An organism that causes a disease.
Vitamin—
A nutrient that the body needs in small amounts to remain healthy but that the body cannot manufacture for itself and must acquire through diet.
QUESTIONS TO ASK YOUR DOCTOR

See also Food contamination ; Food poisoning ; Food safety .

Resources

BOOKS

Bender, David A. A Dictionary of Food and Nutrition. 4th ed (Kindle). Oxford Reference Online. Oxford: Oxford University Press, 2014.

Jones, Keith. Diet and Nutrition Sourcebook. 5th ed. Detroit: Omnigraphics, 2016.

Rodrigues, Sueli, and Fabiano Andre Narciso Fernandes, eds. Advances in Fruit Processing Technologies. Boca Raton, FL: CRC Press, 2012.

Sommers, Christopher H, and Xuetong Fan, eds. Food Irradiation Research and Technology. 2nd ed. New York: Wiley-Blackwell, 2012.

WEBSITES

Organic Consumers Association. “Irradiation: Information on Food Irradiation.” http://www.organicconsumers.org/irradlink.cfm (accessed April 9, 2018).

ORGANIZATIONS

Centers for Disease Control, 1600 Clifton Rd., Atlanta, GA, 30333, (800) 311-3435, http://www.cdc.gov .

U.S. Department of Agriculture, 1400 Independence Avenue SW, Washington, DC, 20250, http://www.usda.gov .

U.S. Food and Drug Administration, 10903 New Hampshire Ave., Silver Spring, MD, 20993, (888) 463-6332, http://www.fda.gov .

World Health Organization, Avenue Appia 20, Geneva, Switzerland, +41 22 791-2222, http://www.who.int/en .

Tish Davidson, AM
Revised by Laura Jean Cataldo, RN, EdD

  This information is not a tool for self-diagnosis or a substitute for professional care.