One day while shopping in your local supermarket in the next few years it's likely you'll run across a loaf of Arnold brand 100% Whole Wheat Bread with a label saying something like “Produced with Genetic Engineering.”

Multiple states are passing or debating laws that would require most packaged foods to declare whether genetic modification was used in their production, including Maine, Vermont, Connecticut, Oregon and Colorado.

Some of the details that vary from state to state could cause headaches for the food industry. But the proponents of labeling claim to be more concerned with you, the consumer. The “right to know” language of labeling campaigns is geared to appeal to people who purchase these products.

And you, dear consumer, agree: you DO have a right to know what's in your food.

Of course, being the scientifically-minded person you are, you don't buy into epithets of “frankenfoods.” Your concerns are for the legitimate implications – the direct impact a genetically engineered food might have on your family's health and the indirect effect that buying this particular genetically modified food might have on the environment.

You also know that genetic modification encompasses a wide array of different procedures done to different crops for different purposes. One GM crop might be unhealthy, while another might be better for you. One might be growing out of control, while another might reduce soil erosion or water usage. The details matter.

So you take a loaf of that Arnold bread off the shelf and scan the ingredients. There are 20, including whole wheat flour, sugar, raisin juice concentrate, molasses, soybean oil and whey.

Which of these ingredients, you ask yourself, is the GMO?

You can't tell.

Why not? One thing the labeling laws have in common is a provision that prevents the identification of GMO ingredients. Oregon's proposal, which was created by right-to-know activists, spells it out clearly: “This law shall not be construed to require either the listing or identification of any ingredient or ingredients that were genetically engineered.”

Already you're on your own.

A GMO “right to know” advocate holds up his protest sign. As written, labeling laws wouldn't allow him to know anything he can't already find out. Photo by Daniel Goehring [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.

Even being able to identify the ingredient, of course, wouldn't tell you exactly what was done to the food. State definitions of genetic engineering include processes such as direct injection of nucleic acids into cells or organelles. But they don't tell you anything about what was introduced into the organism or how it will change the organism. And no food company will be required to tell you – such proprietary information about the processes used would be difficult to legally compel from any corporation.

What's a consumer to do? Well, you can search the published literature for any publicly available studies on the plethora of practices commonly used on various agricultural products. You can sort through them, evaluating them for their strengths and weaknesses.

Not that you can be sure any conclusion you draw from this research applies to your loaf of bread, or even that the publicly accessible literature contains anything relevant to your personal quest for information.

Heck, you can't even find out where the ingredients were sourced from!

Moreover, this is something you could do before the labeling laws took effect. The labels cannot give you any better information than you already had.

In an ideal world, what you'd really like to do be able is to make comparisons with your other food options. Artificial selection, hybridization, and other plant breeding programs also modify plant genes, albeit in a more hit-or-miss fashion. Some of these programs have been highly successful. Ever compare the taste of a crabapple with its domesticated, hybridized counterpart?

But other efforts have failed miserably. Bananas, which are sterile hybrid clones, are extremely susceptible to disease because they have so little genetic variation. In fact, the now-rare Gros Michel cultivar was predominant until the mid-twentieth century, when Panama disease killed the entire worldwide crop, and farmers frantically switched to today's Cavendish - which faces a near-identical disease threat today.

Some groups are trying to genetically engineer more disease-resistant bananas. If it works, several varieties of bananas – including food staples in some countries - might be saved. In the meantime, the industry is trying every trick in the book to save our bananas, with no luck so far.

Is a disease-resistant GM banana better than an extinct banana? It's a gamble, like any other experiment. But then, so were the “traditional” breeding practices that cultivated bananas in the first place. And none of them require labels.

This isn't an ideal world, unfortunately. Your GMO label can't tell you anything about these and other tradeoffs.

In reality, the establishment of your “right to know” hasn't given you any useful knowledge. So go ahead and buy the bread already.