June 2021

Food irradiation is a common practice that is frequently misunderstood. Not only has the process of exposing food products to ionizing radiation, including X-Rays or electron beams, been heavily researched and utilized safely for over a century, it is a process that has proven benefits for the health of human beings.

The history of food irradiation.

The process of irradiating food began as early as 1905 when patents were issued in the U.S. and Great Britain to use ionizing radiation to kill bacteria found in foods. After World War II, research was conducted by the U.S. Army to verify the safety and efficacy of the irradiation process for meat, dairy products, fruits, and vegetables. Food irradiation has been controlled by the Food and Drug Administration since 1958 and recognized by the United Nations since 1964, when the first meeting of the Joint Expert Committee on Food Irradiation took place. It was determined by this committee in 1980 that “irradiation of foods up to the dose of 10 kiloGrays introduces no special nutritional or microbiological problems,” and the use of irradiation in the U.S. food supply was expanded by the FDA in 1986. In addition to the FDA and the UN, irradiation has been endorsed by the World Health Organization (WHO), the Centers for Disease Control and Prevention (CDC), and the U.S. Department of Agriculture (USDA).

Why irradiate food?

There are several important reasons to irradiate food which ultimately benefit humans.

Prevention of Food borne Illness – Nobody likes having food poisoning. Food irradiation eliminates bacteria and molds like Salmonella and Escherichia coli (E. coli) which can spoil food and cause serious foodborne illnesses.

Sterilization – Irradiated foods can be used to sterilize foods which do not require refrigeration. These can be used in hospital settings for individuals with compromised immune systems or those undergoing chemotherapy. A variety of household and consumable products are also irradiated for sterilization purposes, including Band-Aids, cotton balls, medical products like surgical gloves, and even cosmetics.

Preservation – Have you ever wondered why spices have such a long shelf life, or why that bag of potatoes you bought last week is still sprout free? The answer is food irradiation. Food irradiation can extend the shelf life of certain foods by destroying organisms that cause spoilage and early sprouting.

Pest-Control – Irradiation helps control invasive insects that live in or on imported fruits and vegetables by killing or sterilizing them to prevent new bugs from infecting U.S. crops. This method is also safer than certain pest-control practices which have the potential to harm the produce through the use of toxic chemicals.

Of course, the benefits to irradiating food do not diminish the need for safe food handling practices by growers, processors, and consumers. All food should be stored, handled, and cooked appropriately. If safe handling practices are not followed, disease-causing organisms can still contaminate food and illness can occur.

It also does not completely remove all food dangers. For example, food irradiation can slow fruits and vegetables from aging, but it does not stop them. It also does not eliminate dangerous toxins that are already in food, such as Clostridium botulinum, a common bacterium which produces a toxin that causes botulism.

What kind of foods are irradiated?

In the United States, the FDA has approved a variety of foods to undergo irradiation, including:

Beef and Pork
Poultry
Lobster, Shrimp, and Crab
Fruits and Vegetables
Lettuce and Spinach
Shell eggs
Shellfish
Spices and Seasonings

The international symbol for irradiation is called the Radura. This green symbol is required to be present on food packaging of irradiated food alongside the statements “Treated with radiation” or “Treated by irradiation.” According to the FDA, bulk foods like fruits and vegetables must be individually labelled with this symbol, however it is not required for individual ingredients in multi-ingredient foods, such as spices, to be labelled. If this symbol is present, this also indicates that the food is not classified as organic no matter how it was grown or produced.

How is food irradiated?

The overall process is simple. Three different kinds of radiation are approved for use: Gamma rays, electron beams, or x-rays. Packaged or bulk food pass through a radiation beam in a radiation chamber on a conveyor belt. The ionizing radiation breaks the chemical bonds into the bacteria or mold cells, which kills or damages the pathogens enough that they cannot multiply. This process does not affect the taste or smell of the food being irradiated.

This process also does not bring food into contact with radioactive materials, nor does it make food radioactive. Irradiated food does not expose those who eat it to radiation.

Are there risks to eating irradiated food?

Eating irradiated food is not harmful and there are no radiation-related risks. In fact, irradiating foods increases the availability of healthy and nutritious food supplies on a global scale. The chemical changes to food caused by irradiation are comparable to the changes food undergoes when cooked or canned.

Safe and beneficial.

Exposing food products to ionizing radiation is a safe, heavily researched process endorsed by governing agencies around the world. It is responsible for controlling invasive insects, destroying harmful bacteria that can cause food borne illnesses, and increases the shelf-life of certain foods which allows for more widespread access to healthy, nutritious food. This process also poses no radiation-risks to the public.

Further reading:

http://hps.org/publicinformation/ate/faqs/foodirradiationqa.html

https://www.epa.gov/radtown/food-irradiation

https://ccr.ucdavis.edu/food-irradiation/history-food-irradiation

https://www.fda.gov/food/buy-store-serve-safe-food/food-irradiation-what-you-need-know

Background radiation is all around us, and always has been. That idea can be a frightening concept at face value, but the truth is background radiation is natural, normal, and expected.

Most natural background sources of radiation fall into one of three categories:

Cosmic Radiation

Think of this as steady waves of external radiation being sent from the sun and stars in space to Earth. This type of radiation occurs naturally and introduces extremely low levels of radiation to the average person. The amount (or dose) of cosmic radiation one receives can depend on weather and atmospheric conditions, the Earth’s magnetic field, and differences in elevation. For example, people who live at higher altitudes like Denver, Colorado are exposed to slightly more cosmic radiation than people who live in lower altitudes, such as New Orleans, Louisiana or Miami, Florida. Furthermore, the farther north or south one is from the equator results in a higher dose of cosmic radiation due to the way the Earth’s magnetic field deflects cosmic radiation toward the North and South poles.

silver airplane flying above orange clouds

Air travel can also expose individuals to low levels of cosmic radiation. The received dose is similarly dependent on altitude, latitude, and the duration of the flight. A coast-to-coast flight in the United States would expose an individual to approximately 3.5 mrem. For comparison, a typical medical procedure involving radiation, such as a chest X-ray, exposes an individual to 10 mrem, and the average American receives a total radiation dose of 540 mrem each year.

In general, a person’s average dose from cosmic radiation in the United States is small, making up only 6% of their total annual dose.

Terrestrial Radiation

Terrestrial radiation is the portion of natural background radiation that is emitted by naturally occurring radioactive materials on earth, and it is responsible for approximately 3% of the average person’s annual received dose. The physical earth, including soil and sedimentary and igneous rock, contains common elements like uranium, thorium, and radium. These naturally occurring radioactive materials, which have existed as part of the earth’s crust since the earth was formed, are released into the water, vegetation, and the atmosphere as they breakdown at different rates. People are largely exposed to the resulting emitted radiation through their skin.

Radon:

Perhaps the most significant form of terrestrial radiation is that which is inhaled. When the naturally occurring radioactive element uranium (found in the earth’s crust, underwater caves, and seawater) decays it can change into a scentless, invisible gas called radon. All the air we breathe contains trace amounts of radon, and it is responsible for the largest portion of background radiation dose that the average American receives in a year. Outdoors, this radioactive gas disperses rapidly and does not pose any health risk to human beings. A build-up of radon gas indoors, however, can potentially increase the risk of lung cancer over time, which is why it is important to test homes and workplaces for radon on a regular basis. Smoking, especially near or inside the home, can amplify the risk of cancer when coupled with radon exposure.

The average person can expect to receive 42% of their annual radiation dose from radon.

Internal Radiation

Background radiation can also be received through ingestion. Some common foods contain small amounts of radioactive elements that do not pose a radiation risk to the person ingesting them. The most common example is the banana. This delicious, nutritious fruit contains naturally high levels of potassium which helps muscles contract, keeps your heartbeat regular, and offsets the harmful effects of sodium on blood pressure. A tiny portion of potassium is also naturally radioactive. A single banana emits 0.01 mrem, which is received internally by the person eating it. According to the EPA, a person would have to eat 100 bananas to receive the same amount of radiation exposure naturally received each day from the environment. (It should be noted that this naturally occurring radiation is not the same thing as food irradiation, which is a process used by humans to kill bacteria, molds, and pests to prevent foodborne illnesses and spoilage.) Overall, the levels of natural radionuclides found in our food and water are low and considered safe for human consumption by regulatory bodies.

Most surprisingly for some is the fact that other humans are also a source of exposure to one another. From birth, people have internal radiation in the form of radioactive potassium-40, lead-210, and carbon-14. These elements reside in our blood and bones. As previously noted, humans also ingest traces of naturally occurring radioactive material found in our food and water. When our bodies metabolize the non-radioactive and radioactive forms of potassium and other elements, they then contain small amounts of radiation which can act as exposures to others.

Man-Made Radiation Exposure

A more familiar source of radiation exposure to many is man-made radiation, such as procedures using X-Rays and radiation therapy to treat cancer. According to the Health Physics Society, approximately 42% of annual dose comes from man-made radiation. This percentage includes medical procedures, household products like smoke detectors, and small quantities of normal discharges from nuclear and coal power plants.

Learn more about the health effects of man-made ionizing radiation in our blog post here.

Conclusion

Natural background radiation has always been a part of life on earth, and it always will be. It is important to understand that this is not something to be feared. Low levels of ionizing radiation from naturally occurring sources such as space, the ground beneath our feet, and even some of the food we eat are not dangerous and do not pose a direct health risk to ourselves or our loved ones.

For more information, visit the Health Physics Society webpage, epa.gov, or the International Atomic Energy Agency.

Note: Visit our regulatory page to learn how Versant Physics’ board-certified Internal Dose Specialists, Medical Physicists, and Health Physicists, can assist with your radiation safety program needs.

Additional Sources:

https://www.nrc.gov/about-nrc/radiation/around-us/sources/nat-bg-sources.html

https://www.cdc.gov/nceh/radiation/air_travel.html

NCRP Report 160

NCRP Report 184