Irradiation gets high marks as a spoilage deterrent, although it is presently not used by American food producers. At low levels, radiation kills some spoilage organisms and slows ripening and sprouting of fresh produce. Low-level irradiation can inhibit insect infestations and sprouting. The shelf life of meat, poultry and fish can be extended without significant nutrient losses. At high doses, radiation can totally sterilize a food, theoretically extending its life indefinitely.
At any level, radiation can help to reduce dependence on chemical preservatives, including such potentially harmful ones as nitrates and nitrites.

Microwave ovens may become a popular preserving technique in the future. Dr. Gertrude Armbruster, a Cornell nutritionist, reported that heating a cup of pasteurized milk in a microwave oven for two minutes at full power destroys enough microorganisms to increase its refrigerator life from 10 days to nearly three weeks with virtually no nutrient loss.

A major worry about irradiation has focused on the fact that, even though the foods do not become radioactive, substances called ”radiolytic products” can be created in the foods. The amount of such products formed depends on how much radiation the food absorbs. The F.D.A. says that at the levels used in preserving foods, the amount of radiolytic products would be so small as to have no bearing on safety or food quality.

While many consumers and some watchdog agencies, like the Health and Energy Institute in Washington, are strongly opposed to food irradiation, others, like Dr. Silbergeld, clearly favor it over most chemical preservatives. ”The danger, if there is any, is not to the consumer, but to the workers who may be accidentally exposed to radiation,” she said. Additional risks to the population could result from disposal of radioactive wastes.

Irradiation has attracted interest as a food preservation technique, in part because the treatment itself is not harmful to nutrients and irradiated foods lose fewer nutrients during storage. Applying a coating of wax to fruits and vegetables may also help to slow the loss of some nutrients.

Foods Currently Being Irradiated

Internationally, foods such as apples, strawberries, bananas, mangoes, onions, potatoes, spices, seasonings, meat, poultry, fish, and grains have been irradiated for many years. Since 1991, Japan has irradiated more than 20,000 pounds of potatoes each year to prevent sprouting. In the Netherlands, more than 18,000 pounds of foods such as strawberries, spices, poultry, and dehydrated vegetables are irradiated daily. Belgium irradiates more than 8,000 tons of food per year. Canada irradiates potatoes, onions, wheat flour, fish fillets, spices, and seasonings. More than 35 countries have approved irradiation of some 40 different food products.

In 1986, the United States Food and Drug Administration (FDA) approved irradiation of spices and seasonings up to 30 kGy to reduce microorganisms and insects. Irradiation of spices and seasonings reduces the dependency on chemical fumigants. Fruits such as avocados, mangoes, and papayas imported into the U.S. have been approved to receive irradiation treatments of 1 kGy maximum to control non-native insects such as the Medfly. Potatoes and onions have been approved to receive 0.05 to 0.15 kGy to inhibit sprouting, while a maximum of 1 kGy can be applied to grains, such as wheat and oats, to prevent insect infestation. Raw pork has been approved to receive irradiation doses up to 1 kGy to destroy Trichinella spiralis, a deadly parasite.

In 1990, FDA approved the irradiation of poultry up to doses of 3 kGy to eliminate harmful bacteria such as Salmonella spp., Escherichia coli O157:H7, Campylobacter jejuni, and Listeria monocytogenes. In September of 1992, USDA Food Safety and Inspection Service (FSIS) approved facilities to irradiate raw, packaged poultry. In December of 1997, FDA approved the irradiation of red meats up to doses of 4.5 kGy for fresh and 7.0 kGy for frozen product for the elimination of food poisoning bacteria such as Escherichia coli O157:H7. The irradiation and inspection of meat and poultry products is under the jurisdiction of the FSIS.