Waiter, There's A Hair In My Soup

The US Food and Drug Administration uses the Defect Levels Handbook to establish maximum levels of natural or unavoidable defects in foods for human use that present no health hazard.

For example, it's not considered unhealthy when peanut butter contains insect fragments to a maximum of 30 per 100 grams, or 1 rodent hair per 100 grams. Canned tomatoes may contain a maximum of 10 fly eggs per 500 grams, or 1 maggot per 500 grams. And popcorn may contain 1 rodent excreta pellet per pound.