It sounds outrageous, but it's true; the U.S. Food and Drug Administration does, in fact, allow for certain foods to be sold even when they contain a small amount of rodent hair. There's one common grocery product in which at least one or more rodent hairs is allowed in every 100 grams.

Peanut butter is "one of the most controlled foods in the FDA list" of food defect standards, per CNN. 100 grams of peanut butter amounts to 3.5 ounces, and a jar is usually between 10 and 16 ounces or more.

The FDA’s Compliance Policy Guide on peanut butter doesn't specify how small the hair fragments are or how they're mixed in with the peanut butter. It’s possible for a 12-ounce jar to have no rodent hairs at all or have three or more hairs in it, but the important thing to remember is although gross, it’s harmless.