The Food and Drug Administration has escalated a recall of popular potato chip brands Dirty and Zapp's to its most serious classification, warning the products may be deadly. The action, detailed in the agency's July 1 Enforcement Report, upgrades a voluntary recall initiated in May by manufacturer Utz Quality Foods.

Utz originally pulled select varieties of Dirty and Zapp's chips out of caution after their seasoning was found to contain dry milk powder from California Dairies potentially contaminated with Salmonella. The FDA's Class I designation indicates a reasonable probability that using or exposing oneself to the product could cause serious adverse health consequences or death.

Salmonella infection can cause serious and sometimes fatal illnesses, particularly in young children, frail or elderly people, and those with weakened immune systems. Healthy individuals often experience fever, diarrhea, nausea, vomiting, and abdominal pain. The recall comes just ahead of July Fourth celebrations, when many Americans will be hosting barbecues and potentially serving the affected snacks.

The recall affects only specific varieties of Dirty and Zapp's chips, not all products under those brands. Consumers are urged to check their pantries and discard any recalled items or return them for a refund. The FDA has not released a full list of affected batch numbers, but Utz has previously published details on its website.