Just how safe are pre-washed packaged salads?

University of Georgia News reports that questions are being asked about the safety of bagged salads, even though the popular mixtures are pre-washed.
The U.S. Food and Drug Administration and the produce industry say prewashed salads can be eaten without further washing.
However, food-safety researchers who purposely contaminated lettuce in lab tests didn’t find washing, even with bleach water, very effective in eliminating E. coli.
Produce can be tainted by workers’ unwashed hands or contaminated rinse water, but since E. coli is found in fecal matter, any lettuce can be contaminated by irrigation water or runoff from livestock pastures near growing fields.
The safest possible course may be to purchase head lettuce and discard the outside leaves.
”If you were to eat bagged lettuce, the likelihood of becoming ill is quite low,” says Mike Doyle, director of the University of Georgia Center for Food Safety. “But that’s not to say it doesn’t happen.”