According to the U.S. Food and Drug Administration Division of Compliance Management and Operations, peanut butter is fit for human consumption if it contains fewer than 30 insect fragments per 100 grams. Peanut butter can also have no more than one rodent hair per 100 grams in order to pass the FDA regulations.
The FDA has established mold, insect filth and rodent filth levels for foods other than peanut butter. Chocolate, cornmeal, prunes, cherries and many other foods can have an acceptable amount of undesirable fragments in them. Rot is also allowed in the food supply, with the FDA allowing potato chips with less than 6 percent rot by weight to be passed to the consumer.