WASHINGTON - The recent outbreak of E. coli in spinach from California exposed a weakness in the nation's food chain: A system that quickly delivers meat, fruits and vegetables to consumers just as easily can spread potentially deadly bacteria.
Like most food, spinach travels from the field to a central facility where it mixes with spinach from other fields. If any is tainted, the threat to people is amplified as leaves are washed, dried, bagged and shipped throughout the country.
Within days of the first reported E. coli-related case on Aug. 30, illness from the tainted California spinach had spread to two dozen states. Nearly 200 people were sickened - one-third of them in the first 72 hours. Two elderly women and a 2-year-old boy died.
"When you open a bag of spinach, do you wonder how many different plants are in there, and how many different fields it came from?" said Dr. Robert Tauxe, chief of foodborne diseases at the federal Centers for Disease Control and Prevention.
"If something went wrong on any one of those fields ... one rotten apple spoils the whole barrel," Tauxe said.
It was the 20th time lettuce or spinach has been blamed for an outbreak of illness since 1995.
On Sunday, green leaf lettuce from the same growing area, California's Salinas Valley, was recalled in more than half a dozen states after Nunes Co. Inc. discovered possible E. coli contamination of irrigation water. The bacteria hasn't been found in the company's Foxy brand lettuce. No illnesses have been reported.
Food safety advocates are calling for stringent regulations, and they say a single agency should be in charge of making sure all food is safe.
"If you raise spinach in the Salinas Valley and it's in 40 states in a few days, you can't have a system that says we won't do anything until somebody gets sick," said Carol Tucker Foreman, director of food policy for Consumer Federation and a former USDA official.
"Because look how many people get sick before you can even know it," Foreman said.
The Food and Drug Administration has repeatedly told the entire industry to get the problem under control, but FDA does not have inspection or safety programs for produce like the Agriculture Department has for meat and poultry.
While the food system is vastly centralized, "what we don't have is a centralized agency that's really in charge of ensuring that the products are safe," said Caroline Smith DeWaal, director of food safety for the Center for Science in the Public Interest.
An E. coli outbreak in 1993 was a painful demonstration of weakness in the highly centralized beef supply chain. Hundreds of people got sick and four children died after eating undercooked hamburgers from Jack in the Box restaurants.
The outbreak prompted the Agriculture Department to tighten safety standards and expand government testing. And in 1996, it replaced its old visual inspection with one that requires a scientific look at vulnerable places in the production chain and constant monitoring of those points.
Today, illnesses from E. coli are down 29 percent from when the government tracking system began a decade ago, although illness rates inched up from 2004 to 2005.
"It took a few years, but I think we have a really good handle on how to control this organism," said Randy Huffman, vice president of science for the American Meat Institute, an industry group.
The company at the center of the spinach crisis, Natural Selection Foods, has begun sampling every lot of greens and holding shipments until test results come back.
"Even if we nail this particular problem down to a certain point, I think it's really important to have that firewall in place, so no matter where it might come from, we feel like we can catch it," company spokeswoman Samantha Cabaluna said.
With beef, an important step was figuring out just how contamination happened in the first place. Government scientists discovered the primary source entered the slaughterhouse on the hides of cattle, and that it could transfer directly to the surface of the meat.
Solving that mystery may be more critical for lettuce and spinach because - unlike beef - much of leafy produce is eaten raw and not cooked to temperatures that will kill E. coli.
So far, no one has determined the cause of nine outbreaks, including the one from late August, in lettuce and spinach grown in Salinas, Calif.
In the spinach case, the FBI has searched processing plants for evidence of problems and state investigators are looking into contamination from manure, irrigation water or even workers relieving themselves in fields.
In addition, it is unknown exactly where E. coli lurks in spinach and lettuce plants. Research suggests the bacteria can get inside the stems and leaves, Tauxe said, adding that more research is needed.
It's unlikely whether FDA will ever know if the E. coli bacteria was on the surface of the tainted spinach or inside the greens themselves, because it was ground up for testing, Dr. David Acheson, chief medical officer in the FDA's Center for Food Safety and Applied Nutrition, told reporters Monday.
Tauxe said: "It took the meat industry some years to get a grip on how contamination was occurring during slaughter, and it will take some time for the produce industry to get a better handle on this."