Should bagged, pre-washed salad greens be washed again in the home kitchen?

Many food safety types say no.

During the idle but oh-so-smoothing brand of chat-chit practiced by National Public Radio that preceded a story about E. coli and Salmonella in leafy greens from Salinas, Calif., one reporter said, “I wash it every time but I don’t know if it actually helps.”

Reporter Dan Charles responded, “It says prewashed but washing might help.”

So might a lot of others things not fit for this family publication.

A review paper published in Food Protection Trends in 2007 contained guidelines developed by a panel of food safety types and concluded:

"… leafy green salad in sealed bags labeled ‘washed’ or ‘ready-to-eat’ that are produced in a facility inspected by a regulatory authority and operated under cGMPs, does not need additional washing at the time of use unless specifically directed on the label.”

The panel also advised that additional washing of ready-to-eat green salads is not likely to enhance safety.

“The risk of cross contamination from food handlers and food contact surfaces used during washing may outweigh any safety benefit that further washing may confer."

When washing at home, "there’s a risk that is the sink where you just washed your chicken," said Donald Schaffner, Rutgers University professor of food science, in a 2011 interview.

Today’s NPR soothfest revisited what growers in California are doing to enhanced food safety and the 2006 E. coli O157:H7 outbreak in spinach that killed 3 and sickened at least 200.

Will Daniels, senior vice president for operations and organic integrity at Earthbound Farm, based in San Juan Bautista, told NPR, "I was at the center of the investigation and really took it very hard. It was just a real tough time to go through, and something that I don’t ever want to go through again."

Investigators found E. coli bacteria that matched the microbes that were making people sick on a ranch that was one of Earthbound’s suppliers. But those bacteria were in animal feces a mile from the spinach field, Daniels says, "with no clear indication of what caused the contamination from a mile away to get into the spinach field itself."

"Unfortunately, it looks like every animal is suspect," says Bob Martin, general manager of Rio Farms, in King City, Calif.

Even birds. "Birds are a big issue! They carry human pathogens, and we can’t put diapers on them. We can’t dome our fields; there’s nothing we can do, short of trying to scare them away.”

Lettuce fields now have to be separated from cattle pastures, and throughout the valley, next to lettuce fields, you see white plastic pipes. Inside those pipes are mouse traps.

And the birds? Vegetable buyers won’t take anything from the area directly under power lines.

"When it comes to food safety, if it’s grown outdoors, forget it, there’s no such thing as zero tolerance," says Bob Martin. "And everybody knows that, except for some food safety personnel of the big food buyers."

Daniels of Earthbound Farms was further quoted as saying, "It is a true test-and-hold program, so we have to wait to get the negative results before we put it on a truck. Any positives go to the landfill.”

There still are positives. Not very often, but every five weeks or so, one of these tests catches a sample that’s contaminated with disease-causing E. coli or Salmonella.

A table of leafy green related outbreak is available at http://bites.ksu.edu/leafy-greens-related-outbreaks.