What is Food Irradiation?
Food irradiation is a promising food safety technology that can eliminate disease-causing microorganisms such as E. coli O157:H7, Campylobacter, and Salmonella from foods.
The Food and Drug Administration has approved irradiation of meat and poultry and allows its use for a variety of other foods, including fresh fruits and vegetables, and spices. The agency determined that the process is safe and effective in decreasing or eliminating harmful bacteria. Irradiation also reduces spoilage bacteria, insects and parasites, and in certain fruits and vegetables it inhibits sprouting and delays ripening.
The effects of irradiation on the food and on animals and people eating irradiated food have been studied extensively for nearly 50 years. These studies show clearly that when irradiation is used as approved on foods:
- Disease-causing microorganisms are reduced or eliminated
- The nutritional value is essentially unchanged
- Irradiation is a safe and effective technology that can prevent many foodborne diseases.
How does irradiation affect food?
The process involves exposing the food, either packaged or in bulk, to carefully controlled amounts of ionizing radiation for a specific time to achieve certain desirable objectives.
When microbes present in the food are irradiated, the energy breaks the bonds in the DNA molecules, causing defects in the genetic instructions. Unless this damage can be repaired, the organism will die or will be unable to reproduce. It matters if the food is frozen or fresh, because it takes a larger dose to kill microbes in frozen foods. The effectiveness of the process depends also on the organism’s sensitivity to irradiation, on the rate at which it can repair damaged DNA, and especially on the amount of DNA in the target organism. For example:
- Parasites and insect pests, which have large amounts of DNA, are rapidly killed by an extremely low dose of irradiation.
- It takes more irradiation to kill bacteria, because they have less DNA.
- Viruses are the smallest pathogens that have nucleic acid, and they are, in general, resistant to irradiation at doses approved for foods.
If the food still has living cells, they will be damaged or killed just as microbes are. This is a useful effect: it can be used to prolong the shelf life of fruits and vegetables because it inhibits sprouting and delays ripening.
Are irradiated foods nutritious?
Yes, the foods are not changed in nutritional value. There are no other significant changes in the amino acid, fatty acid, or vitamin content of food. In fact, the changes induced by irradiation are so minimal that it is not easy to determine whether or not a food has been irradiated.
A big advantage of irradiated food, is that it is a cold process: the food is still essentially “raw”, because it hasn’t undergone any thermal process.
Where can youbuy irradiated foods?
A variety of foods have been approved for irradiation in the United States, for several different purposes. For meats, separate approval is required both from the FDA and the USDA.
The quantity of irradiated foods available is increasing. Current estimates are that 175 million pounds of irradiated spices (one-third of the total) are consumed annually in the US. Recent recalls and foodborne illness outbreaks have caused commercial spice manufacturers to seriously consider irradiation as a food safety intervention. Some stores have sold irradiated fruits and vegetables since the early 1990s. Irradiation is being used for phytosanitary reasons to eliminate the threat to American agriculture from fruit fly infestation. Estimates are that about 35 million pounds of irradiated produce is marketed in the US annually. Most of the irradiated produce is brought to the US mainland from Hawaii or countries such as Mexico, Thailand, India, or Vietnam. Irradiated ground beef is available in some grocery stores, specifically Wegman's in the Northeastern US, Omaha Steaks at about 85 retail stores and Publix in the Southeast. Irradiated ground beef is available by home delivery through Schwan's and by mail order from Omaha Steaks. American astronauts have eaten irradiated foods in space since the early 1970s. Patients with weakened immune systems are sometimes fed irradiated foods to reduce the chance of a life-threatening infection.
In addition, irradiation is widely used to sterilize a variety of medical and household products, such as joint implants, band-aids, baby pacifiers, cosmetic ingredients, wine and bottle corks, and food packaging materials. A growing opportunity for irradiation service providers is the market for irradiated pet treats. Many well known retail chains carry irradiated pet treats.
| Approval |
Food |
Purpose |
| 1963 |
Wheat flour |
Control of mold |
| 1964 |
White potatoes |
Inhibit sprouting |
| 1986 |
Pork |
Kill Trichina parasites |
| 1986 |
Fruit and vegetables |
Insect control
Increase shelf life |
| 1986 |
Herbs and spices |
Sterilization |
1990 - FDA
1992 - USDA |
Poultry |
Bacterial pathogen reduction |
1997 - FDA
1999 - USDA |
Meat |
Bacterial pathogen reduction |
Does irradiation destroy all bacteria?
Irradiation is equivalent to pasteurization for solid foods, but it is not the same as sterilization. Food irradiation can be an important tool in the war against illness and death from foodborne diseases. But it is not a substitute for comprehensive food safety programs throughout the food distribution system. In addition, food irradiation is not a substitute for good food-handling practices in the home: irradiated foods need to be stored, handled and cooked in the same way as unirradiated foods.
Will irradiation increase the cost of food?
Yes, any food processing method will add cost. Canning, freezing, pasteurization, refrigeration, fumigation, and irradiation will add cost to the food. These treatments will also bring benefits to consumers in terms of availability and quantity, storage life, convenience, and improved hygiene of the food.
The increase in price for irradiated fruits and vegetables is estimated at pennies per pound. The price is likely to decline as irradiated foods become more widely available.
Does the irradiation process make food radioactive?
No. Irradiation by gamma rays, X-rays and accelerated electrons under controlled conditions does not make food radioactive. Just as the airport luggage scanner doesn’t make your suitcase radioactive, this process is not capable of inducing radioactivity in any material, including food.
Can irradiation be used to make spoiled food good?
No. Neither irradiation nor any other food treatment can reverse the spoilage process and make bad food good. If food already looks, tastes or smells bad - signs of spoilage - before irradiation, it cannot be “saved” by any treatment including irradiation
How do I know if food has been treated with irradiation?
Special labels are required on irradiated foods, including the international symbol of irradiation, known as a “radura”, and a statement indicating that the food was treated with irradiation
Why are we interested in food irradiation?
Irradiation is most useful in four areas:
Preservation. Irradiation can be used to destroy or inactivate organisms that cause spoilage and decomposition, thereby extending the shelf life of foods. It is an energy-efficient food preservation method that has several advantages over traditional canning. The resulting products are closer to the fresh state in texture, flavor, and color. Using irradiation to preserve foods requires no additional liquid, nor does it cause the loss of natural juices. Both large and small containers can be used and food can be irradiated after being packaged or frozen.
Sterilization. Foods that are sterilized by irradiation can be stored for years without refrigeration just like canned (heat sterilized) foods. With irradiation it will be possible to develop new shelf-stable products. Sterilized food is useful in hospitals for patients with severely impaired immune systems, such as some patients with cancer or AIDS. These foods can be used by the military and for space flights.
Control sprouting, ripening, and insect damage. In this role, 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 like insect sprays and fumigants do.
Control foodborne illness. Irradiation can be used to effectively eliminate those pathogens that cause foodborne illness, such as Salmonella.
Presently over 40 countries have approved applications to irradiate approximately 40 different foods. Irradiated food is actually available to consumers in about 30 countries. These food items include fruits, vegetables, spices, grains, seafood, meat and poultry. More than half a million tonnes of food is now irradiated throughout the world on a yearly basis. Although this amount represents only a fraction of the food consumed annually, it is constantly growing. This trend is due to three main factors:
- Increasing concerns over foodborne diseases
Foodborne diseases pose a widespread threat to human health and they are an important cause of reduced economic productivity. Studies by the US Center for Disease Control in 1999 estimated that foodborne diseases cause approximately 76 million illnesses, 325,000 hospitalizations, and 5,000 deaths in the United States each year. Economic losses associated with such foodborne diseases are high-estimated between US $6.5 billion and $33 billion.
- High food losses from infestation, contamination and spoilage.
Irradiation is an important tool in the fight to prevent the spread of deleterious insects and microorganisms. The FAO has estimated that about 25% of all worldwide food production is lost after harvesting to insects, bacteria and spoilage. Economic losses due to insects and microbes have been estimated to fall between $5 and $17 billion yearly in the US alone. Food irradiation can help reduce these losses and can also reduce our dependence on chemical pesticides, some of which are extremely harmful to the environment (e.g. methyl bromide).
- Growing international trade in food products.
As our economies become more global, food products must meet high standards of quality and quarantine in order to move across borders. The FAO has estimated that about 25% of all worldwide food production is lost after harvesting to insects, bacteria and spoilage.