Recent outbreaks of foodborne illness from bagged salad have resulted in 26 cases in three Midwestern states with 10 similar cases occurring in Minneapolis hospitals in three days.

State and federal health officials have launched a wide-ranging investigation to figure out how E. coli O157:H7 got into the lettuce.

Some food scientists wonder if the practice of coring the lettuce right in the field creates an opportunity for E. coli to enter the plant. At the packing plant, the lettuce is chopped, sliced, mixed and washed. Experts fear that in this process, even a small amount of E. coli contamination can be spread around and end up in many bags of salad.

While the investigation is ongoing, consumers can take preventative steps:

  • Wash the salad before serving. Even though bag lettuce is pre-washed and is labeled ready to eat – Wash it again! Chemical rinses and other treatments for washing raw produce (usually called fruit and vegetable washes) are now sold in most grocery stores, however these can be costly. In the home, the best procedure is to wash fruits and vegetables with distilled or bottled water. This method is recommended because distilled or bottled water has been filtered and purified to remove contaminants.
  • If distilled or bottled water is not available, wash the produce for at least one minute under running tap water.
  • Wash your hands. This cannot be stressed enough. Always thoroughly wash your hands with soap and water after handling raw meat and before you handle any other utensils or other food items.
  • Clean food preparation surfaces frequently. Clean the counter top, cutting boards, and utensils with hot, soapy water after preparing each food item. Always clean any surface that has come in contact with raw meat, before any other item is placed on that surface.
  • Avoid cross contamination by keeping vegetables separate from any raw meats.
  • Refrigerate the bagged salad and keep it refrigerated until serving.
  • Check the expiration date, or the "eat by" date, before serving. Even if the lettuce looks good, you should know that E.coli can grow quickly in deteriorating greens.