Food recalls are pretty common for things like rocks, insects and plastic

Rocks in Trader Joe’s cookies. Insects in its broccoli-cheese soup. Pieces of plastic in Banquet frozen chicken strips.

In recent weeks, U.S. consumers have seen high-profile food recalls for an unappetizing reason: They're contaminated with foreign objects that have no place on a dinner plate. And while no one wants to bite down on stainless steel in peanut butter or bone fragments in smoked sausage, this type of contamination is one of the top reasons for food recalls in the U.S.

Food safety experts and federal agencies use the terms “extraneous” or “foreign” materials to describe things like metal fragments, rubber gaskets and bits of bugs that somehow make it into packaged goods.

“Extraneous materials” triggered nine recalls in 2022 of more than 477,000 pounds of food regulated by the U.S. Department of Agriculture’s Food Safety and Inspection Service — triple the number of recalls tied to food contaminated with toxic E. coli bacteria.

And the size of recalls can reach into the millions: In 2019, USDA reported 34 recalls of more than 16 million pounds of food, spurred in large...