Food Irradiation

Why do we use radiation on food?
Food is irradiated to kill germs that might make us ill and to kill insects that may harm the food or us if eaten. In the last several years there have been a number of incidents of food poisoning by E. coli, salmonella, and other organisms. Food irradiation helps to kill insects and germs. The biggest effect of food irradiation on society is an expected significant decrease in sickness and deaths due to food poisoning and food preservation. Another benefit of irradiation is increasing the shelf life of foods because insects and germs that cause food to spoil have been killed. Also, the Food and Drug Administration (FDA) has additional information on its web page "Food Irradiation: What You Need to Know." 
What are the effects of radiation on food?
During food irradiation, the food is exposed to very high levels of radiation that are sufficient to kill just about all of the germs and insects that might be present. It is important to know that this radiation does NOT stay with the food. The radiation used is similar to microwave radiation or to visible light. When we turn the lights off in a room, the room stays dark. While the light was on, items in the room were exposed to the light energy but they don't become a source of light themselves. Similarly, gamma rays and x rays expose food to radiation but the food does not become radioactive.

The Centers for Disease Control and Prevention (CDC), on its page Irradiation of Food (or search “Irradiation of Food”), states, “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.”

According to the CDC, "The high energy ray is absorbed as it passes through food, and gives up its energy. The food is slightly warmed. Some treated foods may taste slightly different, just as pasteurized milk tastes slightly different from unpasteurized milk. If the food still has living cells, (such as seeds, or shellfish, or potatoes) they will be damaged or killed just as microbes are. This can be a useful effect. For example, it can be used to prolong the shelf life of potatoes by keeping them from sprouting. The energy can induce a few other changes. At levels approved for use on foods, levels of the vitamin thiamine are slightly reduced. This reduction is not enough to result in vitamin deficiency."
What are the risks to people who eat irradiated food?
There are no radiation-related risks. Really, the risks are from eating foods that are not irradiated—because of the chance of food poisoning. Irradiation does not make food radioactive. It does not make food dangerous and it does not create dangerous levels of harmful chemicals. There are some chemical reactions that take place due to irradiation, but there are also chemical reactions that take place during cooking, too. And, in fact, chemical changes due to cooking are far more numerous than those due to irradiation.
Are irradiated foods still nutritious?
Yes. Nutrient losses due to irradiation are either not measurable or, if they can be measured, are not significant. Also, the CDC states that, "At low doses, irradiation could be used on a wide variety of foods to eliminate insect pests, as a replacement for fumigation with toxic chemicals that is routine for many foods now." Also, the World Health Organization (WHO) states, "On the basis of the extensive scientific evidence reviewed, the report concludes that food irradiated to any dose appropriate to achieve the intended technological objective is both safe to consume and nutritionally adequate. The experts further conclude that no upper dose limit  need be imposed, and that irradiated foods are deemed wholesome throughout the technologically useful dose range from below 10 kGy to envisioned doses above 10 kGy."
Are irradiated foods on the market now?
Yes. They are mostly dried spices, some fruits, and a limited amount of meats.
How can irradiated foods be identified in the supermarket so I know whether or not I'm buying some?
By regulation, irradiated food must be labeled with a green logo along with the words "Treated with Radiation" or "Treated by Irradiation."

The green RADURA symbol is internationally recognized as an indication of irradiated food and is displayed on foods offered for sale to the public.
Are there set maximum doses for irradiating food in different countries? How is it monitored/measured?
The FDA’s regulations set maximum allowable doses for food irradiation; and these can be found in Title 21 of the Code of Federal Regulations, Part 179.26. Also, the CDC states, "The dose of irradiation is usually measured in a unit called the gray, abbreviated Gy. This is a measure of the amount of energy transferred to food, microbe, or other substance being irradiated. 10 kilograys (10 kGy), or 10,000 Grays, is the same as an older measure, the megarad. A single chest x ray has a dose of roughly a half of a milligray (a thousandth of a gray). To kill Salmonella, fresh chicken can be irradiated at up to 4.5 kilograys, which is about seven million times more irradiation than a single chest x ray. To measure the amount of irradiation something is exposed to, photographic film is exposed to the irradiation at the same time. The film fogs at a rate that is proportional to the irradiation level."
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