But officials have still not pinpointed the source of the contamination. Nor do they know the country or state where the tainted produce was grown, despite a rule issued by the Food and Drug Administration under the bioterrorism law that was intended to give federal officials a way to respond immediately to threats to the nation’s food supply.
The rule requires importers, processors and distributors to keep track of where they buy produce and where it goes. A major hurdle facing investigators in this outbreak, however, is that processors frequently repack boxes of tomatoes to meet a buyer’s demands. In doing so, officials said, they are not required to record the tomatoes’ farm, state or even country of origin.
“The purpose of the recordkeeping provision of the Bioterrorism Act was to support going back to the origin of food after people have gotten sick when you are trying to find out how the biological agent got there,” said Michael Taylor, a professor at the George Washington University and a former F.D.A. official. “But the provisions are of little or no value with respect to trace-backs of fresh produce because of the amount of shoe leather and time it would take.”
The rule requires only that produce handlers keep track of food one step back and one step forward in the supply chain and does not apply to retailers or growers. Because the rule does not specify the format for records, investigators are sifting through a hodgepodge of paper trails to identify the source of the contaminated produce.
“It’s clear that the F.D.A. is not equipped to deal with a trace-back of the magnitude that they are dealing with right now,” said Mike Doyle, director of the center for food safety at the University of Georgia.
Several lawmakers and consumer advocates are calling for a system that requires the industry to track the entire history of food products. Some groups, like the Produce Marketing Association, said they would support national regulation.
Dr. David Acheson, the agency’s associate commissioner for foods, said in a telephone interview on Monday that the F.D.A. lacked authority to require full trace-back capability, adding, “It’s the industry’s responsibility to put that kind of system in place, not ours.”
But Dr. David A. Kessler, the F.D.A. commissioner in the Clinton and first Bush administrations, said the agency has the authority to require the industry to trace produce as it travels from “farm to table,” but has lacked “the impetus” to do so.
“The technology exists to trace the entire chain of a food product,” Dr. Kessler said. “The agency needs to require the industry to put into effect mechanisms to do full trace-back. That regulation could be put in place in months, not years.”
Representative Diana DeGette, Democrat of Colorado, said Congress needed to expand the agency’s authority to “trace contamination to the source.” Ms. DeGette has proposed legislation directing the agency to establish a tracing system.
California requires tomato growers to be able to trace their product from the marketplace to the field, which most do using electronic systems that track codes on boxes, said Jay Van Rein of the California Department of Food and Agriculture.