The American Veterinary Medical Association announced today that an investigation into the source of E. coli contamination in fresh produce will be launched by scientists at the University of California – Davis School of Veterinary Medicine.

The study is being funded by a $1.2 million grant from the United States Department of Agriculture. Crews will collect samples of livestock and wildlife droppings; creek, ditch, and irrigation water; farm soil; and lettuce growing on the farms. Scientists will analyze data to identify the vertebrates that are sources of E coli O157:H7; assess climate, landscape, and irrigation; and determine whether certain farming practices or environmental factors have any association with the contamination of lettuce.

Scientists hope the study also will help them understand the puzzling timing of recent E coli contamination. The bacteria appear more often in Salinas Valley waterways during the winter—when rainstorms wash the bacteria from streets, farms, and rangeland into creeks, streams, sloughs, and rivers. The contamination of fresh vegetables tends to occur during the summer and fall, though.