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Food Irradiation


Food irradiation is a method of treating food in order to make it safer to eat and have a longer shelf life. This process is not very different from other treatments such as pesticide application, canning, freezing and drying. The end result is that the growth of disease-causing microorganisms or those that cause spoilage are slowed or are eliminated altogether. This makes food safer and also keeps it fresh longer.

Food Irradiation has been scientifically proven to improve the quality and safety of the global food supply by reducing spoilage and eliminating pests and bacteria


On the moon and in space shuttles, astronauts have preferred food sterilized with radiation over all other types of preserved foods.  This process used radiation to preserve prepackaged food without refrigeration or freezing.  It destroys all the micro-organisms that normally cause spoilage.

Using lower does of ionizing radiation can lengthen the refrigerated life of fresh fish and chicken for several weeks. Strawberries treated this way can last for about 30 days.  Sealed, treated foods can stay on your shelf at room temperature for years, like canned foods.

The process does not make food radioactive, and irradiated foods look and taste just like the fresh, raw food.

Common uses of food irradiation in the U.S.

  1. Disinfesting tropical fruit from Hawaii and other tropical agriculture areas (Low dose 0.1 to 1 KGy). Hawaii, like most tropical climates has vast amounts of agriculture pests. Agricultural interests in the Continental USA do not want to risk introducing a pest that would damage U.S. agriculture production and export market. The only way to get tree-ripened papayas into the Continental USA is to treat the product with ionizing radiation. Consumers want tasty, tree-ripened fruit from tropical climates, and the average U.S. citizen needs to consume more fresh fruits and vegetable.
  2. Pasteurizing meats and fish (Moderate dose 1 to 10 KGy). Cooking meat kills pathogens. However, when consumers bring uncooked meat into the home, the pathogens are hitchhikers. Various E coli outbreaks in beef hamburger and Salmonella from poultry products make news headlines. Using food irradiation to pasteurize meats and fish can help to eliminate these types of outbreaks. The poultry and beef industry have been very frustrated trying to control some bacteria pathogens. Some strains of E coli bacteria are very pathogenic and very low doses (number of bacteria) can result in kidney damage, especially in young children. This pathogen is especially troublesome in Canada and Argentina, where treating beef with ionizing radiation has not been approved. Both these counties rely upon aggressive Hazardous Analysis and Critical Control Point (HACCP) like inspection instead of other intervention technology, like food irradiation.
  3. Eliminating food spoilage to increase shelf life (Higher dose over 10 KGy). Spices and other ingredients are contaminated with many kinds of microbes. Most do not cause a problem unless the right one gets into the processed food. Spoilage may result in a shortened shelf life. When ingredients are mixed with the commercial prepared food product, the microbes may grow and result in off flavors. The food becomes unacceptable.

Frequently Asked Questions

Why should I be interested in food irradiation?

The United Nations Food and Agriculture Organization estimates that 25 percent of the world’s food supply is lost every year to pests and bacteria while people die of hunger. Hundreds of millions of people worldwide are affected by diseases caused by contaminated food. Irradiation using radioisotopes has proved effective in controlling pathogenic bacteria and parasites in food products such as meat, poultry, fruits and vegetables, and seafood and spices. The process is being utilized in many countries and its use is expanding globally.

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.

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.

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.

Why are we interested in food irradiation?

Presently over 40 countries have approved applications to irradiate approximately 40 different foods. These include such items as fruits, vegetables, spices, grains, seafood, meat and poultry. More than half a million tons 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:

1. Increasing concerns over food borne diseases

Food borne 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 food borne diseases cause approximately 76 million illnesses, 325,000 hospitalizations, and 5,000 deaths in the United States each year. Economic losses associated with such food borne diseases are high-estimated between US $6.5 billion and $33 billion.

2. High food losses from infestation, contamination and spoilage.

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).

3. 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. Irradiation is an important tool in the fight to prevent the spread of deleterious insects and microorganisms.

How does irradiation affect food?

Food irradiation kills microbes, but does not affect food products

The food product does not change when treated with food irradiation. Heat sterilization processes damage both the food and the microbe. Cold sterilization selectively targets the microbe, or pathogen. This is a big advantage to the food industry and consumer. Eliminating the offending microbe while preventing any changes to the food composition is a huge benefit to the food industry and to the consumer.

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 from the radiation 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 larger radiation 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:

  • 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 still nutritious?

Yes, the foods are not changed in nutritional value and they don’t become dangerous as a result of irradiation. At irradiation levels approved for use on foods, levels of the vitamin thiamine are slightly reduced, but not enough to result in vitamin deficiency. 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.

Are irradiated foods available now?

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. However, irradiated foods are not widely available yet. Some stores have sold irradiated fruits and vegetables since the early 1990s. Irradiated poultry is available in some grocery stores—mostly small, independent markets— and on menus of a few restaurants. On the other hand, most spices sold wholesale in this country are irradiated, which eliminates the need for chemical fumigation to control pests. 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.

Does irradiation destroy all bacteria?

No. 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 food borne diseases. It is not a substitute for comprehensive food safety programs throughout the food distribution system. Nor is food irradiation a substitute for good food-handling practices in the home: irradiated foods need to be stored, handled and cooked in the same way as non-irradiated 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 2 to 3 cents per pound. Irradiated poultry and meat products are expected to cost 3 to 5 cents a pound more than non-irradiated meat. The price is likely to decline as irradiated foods become more widely available.

Who makes sure that the irradiation facilities are operated safely?

The effectiveness of the treatment in eliminating pathogens will be regulated as a food safety process, by either the USDA or the FDA, often in concert with State authorities, just as is the case now for milk pasteurization or retort canning. The safety of operations of irradiation facilities is regulated separately. This requires extensive worker training, supervision, and regulatory oversight. Facilities using radioactive sources are regulated by the Nuclear Regulatory Commission (NRC). To be licensed, the facility must have been designed with multiple fail-safe measures, and must establish extensive and well documented safety procedures, and worker training. The safe transport of the radioactive sources is regulated by the Department of Transportation.

Can an accident at a irradiation facility lead to a “meltdown” with release of radioactivity that would contaminate the environment and endanger people living nearby?

No. It is impossible for a “meltdown” to occur in a gamma irradiator or for the radiation source to explode. The source of radiation used at irradiators cannot start a fission chain reaction, and it does not emit neutrons that could activate materials. The walls of the irradiation cell through which the food passes, the machinery inside the cell, and the product being processed cannot become radioactive. No radioactivity is released into the environment.

Do irradiation facilities have radioactive waste disposal problems?

No. The food irradiation facilities themselves do not become radioactive, and do not create radioactive waste. Cobalt 60 is manufactured in a commercial nuclear reactor, by exposing non-radioactive cobalt to intense radiation in the reactor core. The cobalt sources used in irradiation facilities decay by 50% in five years, and therefore require periodic replacement. The sources are removed from the irradiator when the radioactivity falls to a low level, usually between 6% and 12% of the initial level (this takes 16 to 21 years for cobalt-60). The small radioactive cobalt “pencils” are shipped back to the original nuclear reactor, where they can be reactivated for further use. The shipment occurs in special hardened steel canisters that have been designed and tested to survive crashes without breaking. Cobalt is a solid metal, and even if somehow something should break, it will not spread through the environment. Cobalt 60 may also be disposed of as a radioactive waste. Given its relatively short half life (5 years) and its stable metallic form, the material is not considered to be a problematic waste.

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