Mixing raw nuts with roasted ones -- a major "don't" when it comes to food safety -- is believed to be the problem behind the latest nut recall, Food and Drug Administration assistant commissioner for food safety David Acheson told ABC News today.
Acheson said that's the working theory behind new salmonella concerns that have prompted the recall of 2 million pounds of pistachios already distributed nationwide from California-based Setton International Foods, Inc.
"We've learned that on some of the lines, the firm had passed both raw and roasted pistachios, and so the possibility of cross contamination -- so that is the working hypothesis," Acheson said.
The latest salmonella worries come separate from an enormous ongoing peanut recall. Taken together, the recalls mean shoppers have slim pickings today when it comes to eating nuts.
At this early stage in the investigation, health officials are warning consumers to stay away from all pistachios.
"We don't know where these pistachios have gone right now," Acheson said. "What we do know is there is a million-plus pounds of pistachios that are out there somewhere."
After announcing the recall Monday night, the FDA spent today collecting the names of the 36 companies to whom the company at the heart of the investigation sold pistachios. The FDA is beginning the slow process of contacting those who received bad pistachios to figure out where the nuts went from there.
The bad pistachios are believed to be coming from the second largest pistachio producer in the country, Setton International Foods, in Terra Bella, Calif. The FDA and the California Department of Health have been inspecting and investigating the facility for the past few days.
Concerns about bacteria-tainted pistachios surfaced when Kraft Foods tested them as part of a routine analysis and "found a variety of different types of salmonella."
Acheson said today the investigation has so far found that the California plant was also testing its nuts, and did, on occasion, find salmonella.
As a result, he said they put the nuts back through their roaster. The roasting process is supposed to kill the bacteria, provided the machine is roasting properly.
"They had found some positives, and what they did with that was essentially put them back through the roasting process to ensure that any residual salmonella was taken care of," Acheson said.
"They are not obligated to tell FDA or anyone else if they've done that," he added.
Acheson also told ABC News he believes the company did not do subsequent additional tests to ensure the product was safe. He added that even if they did, one negative does not mean a batch is free and clear of the bacteria.
The FDA has announced the recall in advance of any confirmed illnesses. There have been some consumer complaints, but that doesn't mean definitively that the pistachios caused the illnesses.
"The good news is that the government is acting in advance of any illnesses. This means that, in fact, they are being more proactive to protect the public," Caroline Smith DeWaal, food safety director for the Center for Science in the Public Interest, told ABC News today.
The pistachio company at the focus of the investigation packs the nuts in large volume -- about 1,000 to 2,000 pounds of pistachios in each container -- and ships them to some three dozen suppliers and wholesalers that then repack or resell them to many other manufacturers under different brand names.