Nearly 55 outbreaks have been linked to fresh fruits, vegetables, or salads between 1990 and 1998. Then, in July 2002, over 50 young women were stricken with E. coli at a dance camp after eating "pre-washed" lettuce, leaving several hospitalized and one with life-long kidney damage.

In September 2003, nearly 40 patrons of a California restaurant chain became ill after eating salads prepared with bagged, "pre-washed" lettuce. 13 residents of a California retirement center were sickened after eating E.coli-contaminated "pre-washed" spinach in October 2003. 2 residents died.

Then, in 2005, cases of E. coli infections were reported in Wisconsin, Oregon, and Minnesota. The source of the infection was determined to be prewashed, precut, bagged salad mixes manufactured by the Dole Food Company. The FDA issued a Nationwide Health Alert and recalled the products – Classic Romaine, American Blend, and Greener Selection.

The FDA had been trying for some time to alert the California produce industry about the need for safety precautions, but there had been little response from growers. The FDA identified 18 outbreaks of E. coli O157:H7 associated with fresh or fresh-cut lettuce, resulting in 409 illnesses and two deaths, since 1995. Eight of the outbreaks were traced back to Salinas, California.

Further research indicated that industry practices, including irrigation and field drainage methods, may have led directly to the contamination of the lettuce with E. coli O157:H7 due to sewage exposure, animal waste, and other contaminated water sources.

As a result, the FDA stated that it considers any ready-to-eat crops that have come in contact with flood waters to be "adulterated". The FDA warned industry members that food produced under unsanitary conditions will be considered "adulterated, and that enforcement actions would be considered.