Irradiation Almost Erases Risk of Food Poisoning

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In their study, Niemira and his colleagues found a way to draw bacteria into the leaves of leafy green vegetables. The vegetables were then treated either with a three-minute water bath, three minutes of chemical treatment, or irradiation.

The researchers found that washing with plain water did not reduce bacteria levels in spinach or lettuce. Chemical treatment did not significantly reduce E. coli in spinach leaves and was less than 90 percent effective when it came to removing E. coli from lettuce.

Irradiation, however, reduced the level of E. coli by 99.99 percent in lettuce and by 99.9 percent in spinach, the researchers found.

In tests of biofilms that contained salmonella or E. coli, those that contained salmonella died more easily when exposed to radiation, while E. coli was a little bit more resistant, Niemira noted.

Irradiation has been criticized as a stopgap measure that ignores the bigger problem of how food in the United States is grown, processed and sold. Critics also claim that irradiation changes the taste and nutritional value of food, in addition to producing toxic chemicals.

"We have concerns about food irradiation," said Joseph Mendelson III, legal director of the Center for Food Safety. "We think food irradiation is basically a Band-Aid approach to dealing with how you produce food and how you process it."

In addition, Mendelson is concerned about the process itself. "We know that irradiation produces unique substances in food that may have toxic effects. We also know that it affects both the nutritional quality of food and characteristics of the food that make it a pleasure to eat," he said.

"We don't think it's a viable technology. We think it's something consumers should avoid," Mendelson said.

However, supporters of irradiation say that the process is the only practical way to prevent spread of dangerous bacteria and increase shelf life, given the realities of how food is produced today.

"When you consider that the global problem with food will only increase, we need to preserve as much food as possible for distribution as we increase our population," said Dr. Philip Tierno, director of clinical microbiology and immunology at New York University Medical Center.