Food Irradiation: Toxic to Bacteria, Safe for Humans

by Food and Drug Administration (FDA)

A measure FDA announced in the Federal Register this year may go unused because of consumer apprehension. On May 2, 1990, FDA issued a rule defining the use of irradiation as a safe and effective means to control a major source of food-borne illness — Salmonella and other food-borne bacteria in raw chicken, turkey, and other poultry. However, FDA has received written objections that it must evaluate before the rule can go into effect.

Experts believe that up to 60 percent of poultry sold in the United States is contaminated with Salmonella, according to Joseph Madden, Ph.D., acting director of FDA's division of microbiology. Madden adds that studies suggest that all chicken may be contaminated with the Campylobacter organism.

People often become ill after eating contaminated poultry. Symptoms may range from a simple stomachache to incapacitating stomach and intestinal disorders, occasionally resulting in death.

As equipment used to irradiate food is regulated as a food additive, the FDA rule is the first step in permitting irradiation of poultry. However, although the U.S. Department of Agriculture will soon propose a companion rule finalizing guidelines for commercial irradiation of poultry, industry groups cite consumer apprehension as a drawback to implementing the procedure. And reaction to FDA's new rule has elicited more questions than answers.

A Scary Word

Irradiating food to prevent illness from food-borne bacteria is not a new concept. Research on the technology began in earnest shortly after World War II, when the U.S. Army began a series of experiments irradiating fresh foods for troops in the field. Since 1963, FDA has passed rules permitting irradiation to curb insects in foods and microorganisms in spices, control parasite contamination in pork, and retard spoilage in fruits and vegetables.

But, to many people, the word irradiation means danger. It is associated with atomic bomb explosions and nuclear reactor accidents such as those at Chernobyl and Three Mile Island. The idea of irradiating food signals a kind of "gamma alarm," according to one British broadcaster. (Gamma rays are forms of energy emitted from some radioactive materials.)

But when it comes to food irradiation, the only danger is to the bacteria that contaminate the food. The process damages their genetic material, so the organisms can no longer survive or multiply.

Irradiation does not make food radioactive and, therefore, does not increase human exposure to radiation. The specified exposure times and energy levels of radiation sources approved for foods are inadequate to induce radioactivity in the products, according to FDA's Laura Tarantino, Ph.D., an expert on food irradiation. The process involves exposing food to a source of radiation, such as to the gamma rays from radioactive cobalt or cesium or to x-rays. However, no radioactive material is ever added to the product. Manufacturers use the same technique to sterilize many disposable medical devices.

Tarantino notes that in testing the safety of the process, scientists used much higher levels of radiation than those approved for use in poultry. But even at these elevated levels, researchers found no toxic or cancer-causing effects in animals consuming irradiated poultry.

Beyond the Gamma Alarm

Market tests show that once consumers learn about irradiation, they will buy irradiated food. For example, Christine Bruhn, Ph.D., of the University of California's Center for Consumer Research in Davis, Calif., reports that irradiated papayas outsold the nonirradiated product by more than 10 to 1 when in-store information was available. And, Danny Terry, Ph.D., a consumer researcher at Central Missouri State University in Warrensburg, Mo., says that a recent market test he conducted with irradiated strawberries showed that consumers who received written information about irradiation along with the fruit were slightly more interested in buying irradiated products in the future.

Nevertheless, concern about the process remains strong. Since 1989, three states (Maine, New York, and New Jersey) have either banned or issued a moratorium on the sale of irradiated foods. According to a U.S. General Accounting Office report prepared in May 1990 at the request of Rep. Douglas Bosco (D-Calif.), "officials of these states told us that their states took the actions in response to public concern by citizen groups rather than as a result of scientific evidence questioning the safety of food irradiation."

"Something quite aside from food safety appears to lie at the root of the entire controversy, which may explain why it continues to flourish in the face of all safety assurances," says Carolyn Lochhead in the August 1989 issue of Food Technology magazine. "Many opponents charge that the Food and Drug Administration, the World Health Organization, and the nuclear power industry are conspiring to promote the technique as a way to dispose of nuclear waste."

Lochhead discusses concerns that one source of radioactive material for food irradiation, cesium 137, is recovered from spent fuel rods in nuclear power plants. The conspiracy charge promotes unwarranted fear among consumers, says Lochhead.

"For economic, as well as other, reasons," says Department of Energy official Barbara Thomas, "the U.S. commercial nuclear power industry does not attempt to recover material, such as cesium 137, from spent fuel."

According to DOE, commercial irradiators in the United States choose their irradiation source (whether the gamma-emitting radioactive materials cesium 137 or cobalt 60, or accelerators that can produce electrons, x-rays or both) based on practical requirements, such as cost. The product to be irradiated also influences the choice. Many foods require low energy levels to kill harmful organisms, while medical supplies may need higher doses for sterilization.

However, the fallout from a falsely characterized cesium recovery plan has charged the legislative atmosphere. George Giddings, Ph.D., a consultant food scientist and expert in food irradiation matters, sees it as the "single most inciting issue in the food irradiation area." Giddings suggests that legislators are wary of supporting food irradiation measures some critics say are linked to increased nuclear activity, including the production of nuclear weapons.

A 1982 congressional amendment bars using spent commercial fuel for military purposes. The Department of Energy has no interest in changing this law.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.