I have often wondered about the safety of the glue used to attach those little labels on fruit. It annoys me because some fruit (e.g., plums) can be damaged by peeling off the label. While I wash the fruit after I peel the labels, how safe is the stuff they use to hold the labels on?

Jeff Cooper, whom you will instantly recognize as "the father of modern combat pistol shooting," (www.dvc.org.uk/{tilde}johnny/jeff/aboutjff.html) has written, "Safety is something that happens between your ears, not something you hold in your hands." In spite of my never having fired a pistol in combat, I tend to agree with Father Jeff.

On the other hand, Horace (65-8 B.C.), another great philosopher, although perhaps lesser known in certain circles than Cooper, wrote, "Who can hope to be safe? Who sufficiently cautious? Guard himself as he may, every moment's an ambush."

I must agree also with Horace. There is no such thing as absolute safety, except in the wishful mind of the observer.

Regarding the safety of ingested substances: Every substance, without exception, is hazardous in large enough amounts and harmless in small enough amounts. The weight of a lethal dose of potassium cyanide, for example, is at least a few hundred times the weight of label adhesive that one might ingest on an apple.

So even if the adhesive were pure potassium cyanide (which, of course, it isn't; it is U.S. Food and Drug Administration-certified food grade), you'd have to eat a few hundred sticky apples to die from it, and the apples themselves would have killed you long before that. So "fear not, dear friend, but freely live your days" (Robert Louis Stevenson).

Many fruit labels are made with adhesive-free tabs that assist in their removal without skin damage, which can be a particular problem with plums and pears. If a stubborn label leaves some adhesive on your fruit, you can remove it by patting it a few times with the sticky side of the detached label.

But have you ever wondered why it is necessary for growers and packers to label each and every piece of fruit in a crate? Do the produce unpackers at the supermarket need to be reassured that a crate of oranges really contains oranges? Are the labels merely stating the obvious?

No. The labels are used by the retail markets for inventory control. Notice that they contain numbers, the so-called PLU (Price Look-Up) code. The cashier inputs the code number into the computer that used to be a cash register, and the market's database chalks up the sale of one more apple or orange from a specific supplier.

The PLU numbers also are useful to consumers. Conventionally grown fruits have four-digit PLU numbers beginning with 4. Organically grown fruits have five-digit numbers beginning with 9, and fruits of genetically modified plants have five-digit numbers beginning with 8.

By the way, I have heard rumors that the labels themselves are edible. They are not. They're made of paper, polyethylene or vinyl plastic. Eating one won't kill you, but who'd want to, anyway?

Several years ago I read an article on cinnamon that stated rarely in the United States do we use real cinnamon, but in Europe "true" cinnamon is used exclusively.

The Encyclopedia Britannica (1960) calls cinnamon Cinnamomum seylanicum, of the laurel family. Is this the European variety? It further states that this is not the "biblical" cinnamon, which is C. cassia.

On the other hand, the McCormick company labels its cinnamon "canela molida," obviously a different species. Is this an American substitute and, if so, what are we missing in this country?

First, let's dispose of your canela molida. I hate to tell you, but that's not a different species. It's simply the Spanish words for "ground cinnamon." (I can see your incandescent blush from here.)

But you're in good company to be confused. Cinnamon has been the fuzzy focus of factious fluster for centuries, as the spice trade offered several different products as "cinnamon" and as new classification systems named and renamed the various plant species. The major confusion, however, has been between true cinnamon and cassia, a member of the same genus, Cinnamomum.

True cinnamon is the bark of a tree native to Sri Lanka (formerly Ceylon), the most prevalent species names of which are Cinnamomum verum ("true cinnamon") and C. zeylanicum ("Ceylon cinnamon"), of which C. seylanicum is a variant spelling. In continental Europe and the United Kingdom, the word "cinnamon" is limited to this species.

But in the United States, the FDA allows the word to be used not only for real cinnamon, but also for cassia and C. cassia, as well as for the Chinese and Indonesian cassia varieties, which go by several names. As a result, economics have forced the more expensive and more delicately flavored true cinnamon out of most supermarkets -- although it is available from specialty suppliers.

So most of us have been eating cassia, not cinnamon.

Cassia toast, anyone?

Robert L. Wolke (www.robertwolke.com) is professor emeritus of chemistry at the University of Pittsburgh. His latest book is "What Einstein Told His Cook 2, the Sequel: Further Adventures in Kitchen Science" (W.W. Norton, 2005). He can be reached at wolke@pitt.edu.