Many of us wash our lettuce before eating it, regardless of what its packaging says. Many bags of lettuce found at your local grocery store will be labelled as “washed” or “triple-washed,” and health experts explain that this is for a reason.
According to registered dietitian Neva Cochran, M.S., RDN, LD, who spoke with Eating Well, washing pre-washed lettuce at home could be introducing harmful bacteria or contaminate your leafy greens in other ways. Cochran explained to the publication that produce labelled this way is washed with a government-regulated technique.
This happens in a facility that is much cleaner than your own sink. “Leafy greens in sealed bags labeled ‘triple washed,’ ‘washed’ or ‘ready-to-eat’ are produced in a facility inspected by a government regulatory authority and operated under Good Manufacturing Practices,” she said.
As Thrillist‘s Caitlyn Hitt writes, The Food and Drug Administration sets standards for washing foods like lettuce and other leafy greens. These standards cover personal hygiene for the workers, facility design, equipment maintenance, sanitation, and process controls in production and packaging. Food manufacturing facilities where lettuce is washed must follow those practices or they risk being shut down permanently.
Randy Worobo, PhD, associate professor of food science at Cornell University, detailed the washing techniques to Real Simple. “Pre-washed greens are treated with a mix of water and a food-grade sanitizing agent, like hydrogen peroxide or chlorine,” explained Worobo. This mixture, which the Environmental Protection Agency (EPA) says poses no risk at such low levels, “reduces and prevents the spread of bacteria from the produce surface.”
Another good point Cochran made to Eating Well about re-washing lettuce at home is that you might not even realize the risks of contamination in your own kitchen.
"Washing them again [at home] can actually increase the risk for leafy greens to pick up bacteria from your sink, countertops, cutting boards, knives, colanders, salad spinners, bowls or other items or surfaces in your kitchen the greens might come in contact with during the washing process," Cochran said.
If you really think about it, you can extensively clean your own kitchen but still do things at home that the FDA would disallow in a facility that packages the lettuce. Whether they're on your sponge, in the sink, on utensils or on the cookware you're using to prepare food with, there's probably more germs and bacteria there than you might think. Lettuce is also usually eaten raw, so there's no way to really clean off bacteria that could be on it now after you washed it in your own sink.
"The FDA also advises against using commercial fruit and vegetable washes because they may leave residues," Cochran explained. "Plus their safety and effectiveness have not been thoroughly tested or standardized."
