Salmonella contamination mostly occurs with chicken and eggs, but these microbes can survive in peanut butter despite its low moisture content. For the most part, peanut butter is generally safe from Salmonella after it moves through the production chain. The dry roasting process itself kills off any possible Salmonella. If any peanut butter becomes contaminated, it’s usually after the peanuts are roasted. You might remember the Jif peanut butter recall in 2022 after several people got Salmonella infections after eating peanut butter from a Smucker’s facility in Kentucky. Salmonella can be pretty stubborn and can survive in a contaminated jar for the shelf life of the peanut butter because peanut butter is low in moisture and high in fat.
Aflatoxin B1 is considered carcinogenic and is often found in corn and peanuts, particularly if the conditions in which they are harvested are poor. The aflatoxins can contaminate the peanut butter if the processing standards are poor or unregulated. Aflatoxin contamination has been a problem in developing countries. The U.S. Food and Drug Administration tests raw peanuts and peanut butter for aflatoxins, which is why there hasn’t been an aflatoxin outbreak in the United States (per the National Cancer Institute).