After a six-month probe, U.S. and state officials said Friday they could not conclude how spinach became infected with toxic E. coli bacteria that killed three and sickened 205, but that wild pigs were one possible environmental source.
U.S. stores stopped selling uncooked spinach for several weeks starting mid-September after bagged fresh spinach was linked to an an outbreak of E. coli 0157:H7 bacteria.
"No definitive determination could be made regarding how E. coli O157:H7 pathogens contaminated spinach in this outbreak," concluded a report by the U.S. Food and Drug Administration and the California Department of Health Services.
"Potential environmental risk factors for E. coli O157:H7 contamination identified during this investigation included the presence of wild pigs in and around spinach fields and the proximity of irrigation wells used for ready-to-eat produce to surface waterways exposed to feces from cattle and wildlife."
Much U.S. spinach is grown in California's central coastal region and officials quickly started investigating farms in that region, including at Natural Selection Foods, after the September outbreak.
The study, which included detailed DNA analysis, traced 13 bags of Dole brand "Baby Spinach" from Natural Selection Foods with E. coli O157:H7 to four fields in California's Monterey and San Benito counties. They then focused on one farm called Paicines Ranch which is mostly used for cattle grazing, with a small portion leased by Mission Organics, based in Salinas, to grow crops.
The farm owners, Matt Christiano and Sallie Calhoun, former Silicon Valley software company executives, did not return calls or e-mail requests for comment. Their ranch Web page still posts an older response saying: "We lease row crop land to farmers. ... Since we neither farm nor process row crops of any kind, we are unable to comment further."
Of the 205 people who fell ill nationwide from eating contaminated spinach, 103 went to hospitals and three died.
The study released Friday warned that growing ready-to-eat crops near livestock or their waste raised the risk of contamination, and said water used to irrigate fields should be frequently tested.
Firms linked to the spinach outbreak face about a dozen lawsuits from victims, said Bill Marler, an attorney who represents the three who died and 93 who fell ill.
"The industry just seems to have an inability to deal with this ongoing contamination problem and their voluntary guidelines that they have adopted will do nothing to protect the public," Marler said.
He said those who have fallen seriously ill in similar past cases have received settlements as high as several million dollars.