"We do not routinely look at returned goods for every possible microbe, agent, chemical problem that could be in there," Acheson said. "There's just hundreds. It would be very resource-intensive and time-intensive. This issue was around metal fragments. And it did trigger an inspection to look for metal fragments and had nothing to do with salmonella."
Despite reassurances on Wednesday, the FDA said today that it's possible not all store-bought peanut butter is okay to eat. The FDA said that due to the expanded recall -- among the largest ever -- there may be some boutique brands of peanut butter sold in grocery stores that may be suspect.
The expanded recall means the number of companies potentially involved has mushroomed from 77 to an additional 350.
More than 400 products have already been recalled, including items such as peanut butter-flavored cookies, candies, power bars, cereals, crackers, ice cream and dog biscuits. More are expected to be pulled out of the supply chain.
To make sure shoppers don't get sick, health officials have posted several resources online, including updates on recalled products listed by the FDA and updates on illnesses, compiled by the Centers for Disease Control.
The American Peanut Council has also posted a list of companies that say their products are safe to eat.
"If they're not sure even after all of that, the safest thing to do is not to take the chance," Acheson said Friday. "Just simply put the product back in the pantry, back in the refrigerator, and wait as this ongoing recall gains greater clarity and we know that these products can be safely consumed. What we don't want is people to get sick from consuming peanut products around Super Bowl or at any other time of the year."
On Friday, two Democratic lawmakers asked for a criminal investigation of Peanut Corporation of America.
"It is clear that the behavior of the Peanut Corporation of America was egregious – harming hundreds of Americans and endangering many thousands more," wrote Patrick Leahy, D-Vt., and Rosa L. DeLauro, D-Conn., in a letter to acting Attorney General Mark Filip. "We believe it is critical to determine whether the actions and omissions of this company rose to the level of criminal conduct. If crimes were committed, those responsible must be identified and held accountable."
Earlier this week, the Peanut Corporation of American faced reports that it knowingly shipped peanut products from the Georgia plant that could have been tainted.
According to an FDA inspection report, the plant found some type of salmonella in its products 12 times over the last year-and-a-half. After working with outside labs to test the products, the plant then shipped the products if follow-up tests came back negative, despite the initial findings. The FDA inspections also documented unsanitary conditions at the plant, including cockroaches, mold and leaking roofs.
"This is one of the worst inspection reports I've seen in 15 years of practice," food safety attorney Bill Marler told ABC News on Wednesday. Marler is suing the company on behalf of one consumer.
"To any consumers affected by these issues, to the food industry and to peanut consumers everywhere, we are sorry our process fell short of not only our goals, but more importantly, your expectations," the Peanut Corporation of America said in a statement late Wednesday.