E. coli 0157 is a particularly nasty strain of the E. coli that lives and thrives in our digestive tract. Animals such as cows tolerate 0157 far better than people, and often shed the bacteria in their feces. The bacteria can then infect crops such as lettuce, spinach, onions, or even apples when contaminated manure is used as fertilizer, or when contaminated water is used to irrigate fields. Most recently, E. coli 0157 found in bagged salads packaged by Dole sickened over two dozen people in 2005.
These outbreaks, warns Doyle, are an inevitable by-product of the way that many fruit and vegetable manufacturers have streamlined their production and cut costs by doing some of the processing of their ready-to-eat produce right in the fields, and not in the more controlled atmosphere of a factory. He sees it as a dangerous practice that could contribute to contamination. "Two to three years ago, I was asked to go out and view what was going on in the fields when there was an outbreak associated with a fast food restaurant chain from their cut-up lettuce," he told TIME." Every company at the time was using the same concept to process head lettuce they would core the lettuce in the field, remove the outside leaves, and put it in chlorinated water. The goal is to reduce costs, because you don't have to take the waste from the factory and bring it back to the field. The problem is, they are working out in the dirt. There are so many different ways that E. coli can get into the food this way."
The FDA's director of Food Safety and Applied Nutrition, Dr. Robert Brackett, recognizes the riskiness of such processing in the field, and sent a warning letter to the California growers that had provided the contaminated lettuce in last year's outbreak, noting that "claims that 'we cannot take action until we know the cause' are unacceptable."
In response, Kathy Means, spokesperson for the Produce Marketing Association (PMA), which represents the fruit and vegetable growers industry, notes that processing for ready-to-eat products "is happening in a enclosed facility, not in the field. No one is putting produce in bags out there." Because produce can become a source of E. coli 0157 infection only by being contaminated from another source, PMA advocates good agricultural practices, which includes keeping tools and equipment used to cut produce clean and isolated from potential sources of E. coli, as well as regulating how far away portable toilets provided for workers need to be placed from growing produce. One thing they can't control, however, is waste from birds and other infected wildlife that might contaminate fields.