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Packaged Salad Bacteria: New Study Finds Salad Can Contain High Levels of Fecal Bacteria

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Consumer Reports' latest tests of packaged leafy greens found bacteria that are common indicators of poor sanitation and fecal contamination, in some cases, at rather high levels. The story appears in the March 2010 issue of Consumer Reports and is also available free online. Consumers Union today also issued a report [PDF] urging the U.S. Food and Drug Administration (FDA) to set safety standards for greens. FDA food safety legislation pending in the Senate, and passed last summer by the House of Representatives, would require the FDA to create just such safety standards.

The tests, which were conducted with financial support from the Pew Health Group, assessed for several types of bacteria, including total coliforms and Enterococcus--"indicator organisms" found in the human digestive tract and in the ambient environment that can signal inadequate sanitation and the potential for the presence of disease-causing organisms. While there are no existing federal standards for indicator bacteria in salad greens, there are standards for these bacteria in milk, beef, and drinking water. Several industry consultants suggest that an unacceptable level in leafy greens would be 10,000 or more colony forming units per gram (CFU/g).

Consumer Reports found that 39 percent of samples exceeded this level for total coliform, and 23 percent for Enterococcus. The tests did not find E. coli O157:H7, Listeria monocytogenes or Salmonella--sometimes deadly pathogens which can be found in greens, although it was not expected given the small sample size. According to Consumers Union, the goal was to investigate other markers of poor sanitation that should be used in the food safety management of produce.

"Although these 'indicator' bacteria generally do not make healthy people sick, the tests show not enough is being done to assure the safety or cleanliness of leafy greens," said Dr. Michael Hansen, senior scientist at Consumers Unions, nonprofit publisher of Consumer Reports. "Levels of bacteria varied widely, even among different samples of the same brand. More research and effort is needed within the industry to better protect the public. In the meantime, consumers should buy packages of greens that are as far from the use-by date as possible."

For its latest analysis, Consumer Reports had an outside lab test 208 containers of 16 brands of salad greens, sold in plastic clamshells or bags, bought last summer from stores in Connecticut, New Jersey, and New York. Among the findings:

  • 39 percent of samples exceeded 10,000 CFUs (or another similar measure) per gram for total coliforms and 23 percent for Enterococcus, the levels industry consultants deemed unacceptable.
  • 2 percent of samples exceeded French and 5 percent Brazilian standards for fecal coliform bacteria.
  • Many packages containing spinach, and packages which were one to five days from their use-by date, had higher bacterial levels. Packages six to eight days from their use-by date generally fared better.
  • Whether the greens came in a clamshell or bag, included "baby" greens, or were organic made no difference in bacteria levels.
  • Brands for which there were more than four samples, including national brands Dole, Earthbound Farm Organic, and Fresh Express, plus regional and store brands, had at least one package with relatively high levels of total coliforms or Enterococcus.

CU is calling on the Senate to pass pending FDA food safety reform legislation that requires the agency to set performance standards as well as develop safety standards for the growing or processing of fresh produce. It's also asking that FDA formally declare certain pathogenic bacteria--such as E. coli O157:H7, Salmonella, and Listeria--be considered adulterants when found in salad greens.

Until packaged salad becomes cleaner, consumers' best line of defense involves following these procedures in stores and kitchens:

  • Buy packages far from their use-by date.
  • Wash the greens even if the packages say "prewashed" or "triplewashed." Rinsing won't remove all bacteria but may remove residual soil.
  • Prevent cross contamination of greens by keeping them away from raw meat and poultry.

Originally posted on CivilEats.com

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