In a statement posted on a government Web site, Mexican officials said the storage facilities of green onion distributors in California were now targets for the investigation into the cause of recent hepatitis A outbreaks here and in Tennessee and Georgia.
But a top U.S. Food and Drug Administration official appeared to contradict that, saying yesterday that the information-gathering phase of the investigation was largely complete.
Although FDA and Mexican officials are discussing the possibility of visiting California firms, U.S. investigators believe the visits aren't necessary because those distributors have been checked already, said Jack Guzewich, director of emergency coordination and response in the FDA's Center for Food Safety and Applied Nutrition.
The U.S. firms didn't have problems of the sort the FDA identified during inspections last week in Mexico, he said.
"I think they're trying to protect their industry down there," Guzewich said of the Mexican government's statement. "We're always open to identifying new information about contamination, whether it occurs in the U.S. or Mexico. ... But we've been satisfied up until now that we've covered the issues on this side of the border."
In another statement, posted on its Web site yesterday, Mexican authorities accused the FDA of issuing misleading statements "unfairly affecting the image of Mexican products."
"The U.S. authorities insist on pointing to Mexico while admitting they don't know the source of the contamination," the statement said, "and without having examined the entire supply chain. This situation is not acceptable to the Mexican government."
Dr. Javier Trujillo, undersecretary of food safety and quality in Mexico's Department of Agriculture, said in a telephone interview that he learned of the continuing U.S. investigation from Lester Crawford, deputy commissioner of the FDA.
Scallions contaminated with hepatitis A virus have been implicated in an outbreak last month at the Beaver Valley Mall Chi-Chi's that, as of yesterday, had sickened 640 people -- up five from last week.
In its statement, the Mexican government compared the current investigation to one that sought the source of contamination in a hepatitis A outbreak in 1997, when people were sickened after eating frozen strawberries. In that case, the United States initially focused on Mexican strawberry growers, but ultimately laid blame on a firm in California, the Mexican government said in its statement.
Guzewich disputed that characterization.
The strawberry investigation did find sub-optimal conditions at a California company, but there were also troubling findings in Mexico, he said.
An article in a 1999 issue of FDA Consumer, a magazine published by the agency, said that a San Diego food processing company, Andrews & Williamson Sales Co., was ordered by the U.S. District Court for the Southern District of California to pay $1.65 million in fines for lying about the source of the frozen strawberries it sold to the federal school lunch program. It was required by law to provide domestically grown strawberries and instead was shipping Mexican strawberries.
The article also said that at the time FDA investigators visited Andrews & Williamson, the company was not processing strawberries, "so the agency could not observe fruit handling procedures to determine whether processing conditions would allow for contamination."
The end result of the investigation wasn't to assign blame to a particular country, Guzewich said, but to eliminate a practice whereby strawberry pickers used their thumbnails to remove the green tops of the berries. Workers now use small blades to chop off strawberry tops, Guzewich said.
FDA investigators left Mexico on Friday and have no immediate plans to return, Guzewich said.
Investigators did not pinpoint a source for scallion contamination. While the Mexican government has suggested that this essentially exonerated the companies, the FDA has stressed that investigators found sanitation practices that could allow contamination.
There's reason to think that contamination would more likely occur in the field than during the distribution of scallions, since harvesting and packing the produce is so labor-intensive, Guzewich said. But boxes packed with green onions are sometimes opened at various points in the distribution process, so that ice can be added to maintain freshness, he said.
While that raises the possibility of contamination during distribution, U.S. investigators believe it's unlikely. Had there been a problem with contaminated ice, it likely would have affected scallions consumed at even more restaurants, Guzewich suggested.
"There's a lot of inductive thinking as opposed to hard-and-fast things you find," he said. "It's investigative reasoning, saying: 'How can we account for this happening, what are the most plausible scenarios?' "
The current rift isn't the first time the two governments have offered conflicting stories.
Trujillo said last week that Mexican officials provided the names of the implicated Mexican firms to the FDA. The U.S. agency had given no information to Mexico about whether it had actually traced green onions back from the outbreak restaurants to those firms, he said.
But Guzewich said yesterday that the FDA's trace-back of scallions at the heart of a Tennessee outbreak was completed Nov. 14, at which point the results were shared with Mexican officials. The trace-back of scallions linked to an outbreak in Georgia was communicated to Mexican officials by Nov. 17, he said, and that of scallions consumed in Beaver County was completed Nov. 21.
FDA investigators are now working to write up their results, Guzewich said. The four implicated firms must still go through a process to show the FDA that they are using good agricultural practices before they can resume shipping produce to the United States, he said.
"Obviously some of the public statements have been confusing," Guzewich said, "but I think we're trying to work cooperatively."