Understanding irradiation of spinach and iceberg lettuce.
By Amy Paturel
It seems that every month a foodborne-illness outbreak makes the six o’clock news. Leafy greens, such as lettuce and spinach, are some of the biggest culprits—perhaps because they’re usually eaten raw. (Cooking kills most of the bacteria that makes us sick.) From 1996 to 2005, outbreaks of illnesses associated with contaminated leafy greens increased nearly 40 percent (consumption during that period rose 9 percent) and in 2006 E. coli in spinach sickened 205 and caused three deaths.
That’s why many people applauded the FDA’s decision last August to permit the irradiation of spinach and iceberg lettuce—the two most commonly consumed leafy greens—at levels high enough to eliminate harmful bacteria, such as E. coli and salmonella.
It may sound odd to zap food with high-energy rays to destroy bacteria, but “it’s basically concentrated sunshine,” says Christine M. Bruhn, Ph.D., director for the Center for Consumer Research at the University of California, Davis. “The gamma rays used for irradiation are the same rays that come from the sun.” And it is very effective: irradiation destroys 99.9 percent of common foodborne pathogens—even those embedded in the plant tissue (washing the vegetables with water or a chlorinated rinse does not). It does this without compromising taste, texture or nutrition, according to a 2008 study in the Journal of Food Science, which compared these qualities of irradiated versus nonirradiated leafy greens. “From a scientific point of view, it would be difficult to find a justification for not eating irradiated lettuce,” says Jim Dickson, Ph.D., professor in the Department of Animal Science at Iowa State University.