I have on occasion bought the prepackaged bagged salads which are really convenient and quick. I have always wondered how safe they were to eat and how clean the lettuce and veggies were. I happened to come across an article which was published by March 2010 Consumer Reports Magazine and they have done a study on the cleanliness of prepackaged salads. They tested 16 different brands which were purchased in Connecticut, New Jersey, and New York and they found evidence of contamination, especially in packages that were close to the expiry dates.
If you opt to buy the prepackaged salads, Consumer Reports are suggesting that you wash the greens even if the package states that they have been prewashed. You should also buy packages that are the furthest from the expiry date. Another big factor in food contamination is how we handle it once we get it home. You should always keep your fruits and vegetables away from raw meat and use a separate cutting board for meat than for fruits and vegetables. Always wash your hands well and use a clean knife.
Click here to read the Consumer Reports article.