Farms in the Salinas Valley are being evaluated to determine why leafy greens grown in the area, often called the "Salad Bowl of the World" are linked with E. coli.

Officials say lettuce and spinach grown in that area  has been identified in eight of 19 outbreaks of the virulent E. coli O157:H7 strain since 1995. The outbreaks have sickened at least 217 people in nationwide, including two who died in 2003.

Much of the nation’s lettuce is grown in the valley and growers fear continuing infections might erode confidence in their $2 billion annual lettuce crop.

Inspectors told the Los Angeles Times that the evaluation started last month and will continue through the fall.