Peanut butter  that culinary cause célèbre  may contain approximately 145 bug parts for an 18-ounce jar; or five or more rodent hairs for that same jar; or more than 125 milligrams of grit.

In case you’re curious: you’re probably ingesting one to two pounds of flies, maggots and mites each year without knowing it, a quantity of insects that clearly does not cut the mustard, even as insects may well be in the mustard.

The F.D.A. considers the significance of these defects to be “aesthetic” or “offensive to the senses,” which is to say, merely icky as opposed to the “mouth/tooth injury” one risks with, for example, insufficiently pitted prunes. This policy is justified on economic grounds, stating that it is “impractical to grow, harvest or process raw products that are totally free of non-hazardous, naturally occurring, unavoidable defects.”

The most recent edition of the booklet (it has been revised and edited six times since first being issued in May 1995) states that “the defect levels do not represent an average of the defects that occur in any of the products  the averages are actually much lower.” Instead, it says, “The levels represent limits at which F.D.A. will regard the food product ‘adulterated’ and subject to enforcement action.”

Bugs in our food may not be so bad  many people in the world practice entomophagy  but these harmless hazards are a reminder of the less harmless risks we run with casual regulation of our food supply. For good reason, the F.D.A. is focused on peanut butter, which the agency is considering reclassifying as high risk, like seafood, and subjecting it to special safety regulations. But the unsettling reality is that despite food’s cheery packaging and nutritional labeling, we don’t really know what we’re putting into our mouths.

Soup merits little mention among the products listed in the F.D.A.’s booklet. But, given the acceptable levels for contaminants in other foods, one imagines that the disgruntled diner’s cri de coeur  “Waiter, there’s a fly in my soup!”  would be, to the F.D.A., no cause for complaint.