It's about time. The FDA is cracking down on the sale of a natural substance that most of us consume every day. It is the chemical caffeine, and it's the "energy" in energy drinks. (This is a misnomer. They should be called "drinks that do nothing until a chemical stimulant is added.")

Some may argue that the agency is overstepping. But if you're in that camp, you might want to read further and then reconsider.

There is no question that caffeine is a drug, even though many people don't really accept this. The definition from the FDA site makes this clear: "... intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease" and "articles (other than food) intended to affect the structure or any function of the body of man or other animals."

And, caffeine is even packaged as a drug, which you can buy at your favorite pharmacy. NoDoz pills, which contain as much as 200 mg of caffeine roughly the amount in two cups of coffee are sold over the counter.

Part of the story, featured in Wednesday's New York Times, is a lesson about one of the key parameters that determine toxicity dose dependence: an increase in toxicity (or efficacy, or any other property, really) with increasing dose of the drug or chemical. It is the foundation of pharmacology, and is disputed only by homeopaths, aka "Homeopsychopaths" the title of one of our recent exposÃ©s. A surprisingly small quantity of caffeine can kill you.

As such, the latest concern is about the sale of pure, powdered caffeine. The real issue, however, is not the fact that the caffeine can be bought as a powder, but, rather, that this makes it easier for people consume a potentially lethal dose. That would be about one tablespoon or 8 grams, the equivalent to 84 cups of coffee or 40 NoDoz pills. No one is going to consume 84 cups of coffee, but a tablespoon of something that is really easy to buy? Maybe so.

Here's how easy it is. A one kilogram (2.2 pound) package of pure caffeine can be purchased on Amazon for $19. You don't want your kids getting into this bag, since a one kilo bag contains 125 lethal doses (and that number is for adults).

It's not hard to see how some people might get into trouble. The proliferation of energy drinks is surely sending the message that "energy is good," which will undoubtedly lead some people to conclude that more energy is better. It's not that difficult to imagine someone sticking a tablespoon into a big bag of the stuff and mixing it into a drink (it will take only a half a liter of water to dissolve this amount) and there you go.

In the end, this is simply about control of an unregulated drug.

But, is it really a drug? Perhaps the following graphic will convince you. Sure looks like one to every chemist.