At the Natural Grocery Co. in Berkeley, Calif., green shelf tags highlight “non-GMO” verified products, while those products “at risk” of containing genetically modified organisms, or GMOs, are flagged with a damning red sticker.

At Nature’s Pantry, in Kansas City, Mo., prominent displays showcase books and DVDs on the perils of genetic engineering.

At Mile High Organics, two full-time staffers spend their days scrutinizing products to assure they fulfill the company promise of being “Colorado’s only completely non-GMO retailer.”

 “Consumers have about 6 seconds to make product decisions in grocery aisles with thousands of options,” says Mile High Organics Founder Michael Joseph, of Denver. “I believe retailers have an obligation to help them address the issue of GMOs.”

Seventeen years after genetically engineered (GE) food hit the shelves, retailers from coast to coast are doing just that, joining an unprecedented and—and many say—long overdue groundswell to slow the march of GE crops across America’s farmlands and tables.

Today, GE crops (particularly corn, soy, canola and cotton) make up half of all land harvested in the United States; GMOs are present in roughly 80 percent of processed foods. Just six years after the approval of GMO sugar beets, genetically modified sugar makes up half the nation’s sugar supply, according to biotech giant Monsanto. With the January 2011 approval of GM alfalfa (often used for animal feed), and the pending approval of GM Salmon, dairy products and meat are poised to be the next so-called “Frankenfoods.”

Such swift proliferation, along with recent studies showing clear and present environmental impacts of GMOs, have galvanized purveyors and consumers of natural products, spawning everything from theatrical protests to sophisticated lobbying efforts. Many fear we could someday lose our ability to choose genetically unadulterated products—if we haven’t already.

“We have failed as an industry to build a powerful coalition around this issue and now we are in real jeopardy,” says Stonyfield Farm CEO Gary Hirshberg, who spends “90 percent” of his time speaking to stakeholders about GMOs. “Now is the time to act.”

But just what that action should look like—and the role natural products retailers should play—is a matter of great, sometimes ferocious, debate.

Consumers want to know

One of the greatest challenges facing the anti-GMO movement is the fact that many people don’t know what those letters mean.

“The average American, if you asked him or her, ‘Have you ever eaten a GM food in your life?’ would probably say, ‘No,’” explains Jeffrey Smith, an author and long-time anti-GMO activist. A 2006 survey by the Pew Initiative on Food and Biotechnology found that just 45 percent of Americans were familiar with GMOs, and one quarter suspected they had eaten them.

But those numbers might look different today.

According to Schaumburg, Ill.-based SPINS, sales of “non-GMO verified” products were up 10 percent between April 2010 and April 2011, and Smith says attendance at his lectures has skyrocketed in the past year.

“There is more interest and controversy around [GMOs] today than at any time since their commercial introduction,” says Chuck Benbrook, chief scientist for The Organic Center.

Why should a frazzled mom making her way through the grocery aisles care about the genetic make-up of her corn puffs or soy milk? For one, GMOs are almost sure to have been drenched with more herbicides, research shows.

The most common GE seeds are herbicide-tolerant (HT), meaning they have been spliced with genes intended to help them survive weed-killing chemical sprays (specifically glyphosate, otherwise known as Monsanto’s Roundup). BT crops are bred to contain Bacillus thuringiensis, a toxin that kills insects. While BT crops did, as promised, reduceinsecticide use by 65 million pounds between 1996 and 2008, those improvements were dwarfed by a 383 million pound increase of herbicide use, largely due to the boost in HT crops, according to a 2009 report by The Organic Center’s Benbrook. In 2008 alone, GE crops received 26 percent more pounds of pesticides per acre than conventional counterparts. And that number is expanding exponentially, as weeds become resistant to glyphosate, prompting farmers to spray on more or reach for new—potentially more toxic—weed-killers, Benbrook says.

Pesticide risks aside, a mounting body of evidence suggests there may be other health reasons to worry about GMOs.

One landmark study, published in May, found traces of BT toxin in the blood of 93 percent of mothers and in the cord blood of 80 percent of their children. (Previously, biotech companies insisted that the toxins are destroyed during the digestive process.) “Given the potential toxicity of these environmental pollutants, and the fragility of the fetus, more studies are needed,” the Canadian researchers wrote.

Dr. Julian Little, of the Agriculture Biotechnology Council, said the methods used for this particular study were “unreliable.” “Furthermore, this report does not identify any health or safety concerns related to consuming biotech foods,” Little said in a statement. “GM ingredients have been consumed around the world over the past 15 years without a single substantiated health issue.”

Solid, human studies on the health impacts of GE crops are virtually non-existent—a fact that has lead many activist groups (including the Non-GMO Project) to refrain from using health risks as a platform for generating opposition. But Smith, who tours the country talking about the health risks of GM foods, says dozens of animal studies suggest they could cause allergies, digestive problems, impaired immune response, reproductive problems and organ damage.

“GM foods have not been properly tested for human consumption and … there is ample evidence of probably harm,” states the American Academy of Environmental Medicine, in a recent position statement.

A move for better labeling

Benbrook notes that the advent of GE seeds has also brought economic harm to farmers (who pay three to six times more for GE seeds than for conventional) and increased consolidation of the seed industry (which makes non-GMO seeds and products much harder to come by).

Meanwhile, due to seed contamination and pollen drift, even well-meaning organic farmers say they have a hard time guaranteeing that their crops are completely GMO-free. This makes it particularly difficult for retailers to guarantee that the products they carry do not contain GMO ingredients.

 “We are a natural foods store and our customers are incensed that we are selling them genetically modified food. But unfortunately, it is not that easy to get it out of the store,” says Berkeley retailer Bob Gerner, general manager of the Natural Grocery Co.

After an angry customer accosted a stocker in 2003 at his store, Gerner helped launched the People Want to Know Campaign, asking manufacturers to either rid their products of GMO ingredients, or tell customers which products might contain them.

The initiative has since blossomed into the Non-GMO Project, a nonprofit, standardized, third-party verified system for testing ingredients and products for the presence of genetically engineered material. More than 2,000 SKUs have been Non-GMO Project verified, and 2,000 more are in the pipeline, says Megan Thompson, the project’s executive director. But not even that seal necessarily means a product is completely GMO-free.

“GMO-free is not a legally or scientifically defensible claim”—even though some manufacturers make that claim, Thompson says. “To say [a product] is 100 percent free of something means you have to test all of it.”

Although the program has been widely praised across the industry, some have criticized its allowance of minute amounts (less than .9 percent) of genetically modified material. Others say that the high cost of testing can be a deterrent for small companies.

“If we have private certifiers coming out with their own labels and no legislation behind them, it just adds to consumer confusion,” says Joseph, of Mile High Organics, a “non-GMO” grocery delivery company. “I’m not going to ask my suppliers to spend thousands of dollars to be certified by these guys. I’d rather spend the money to do that leg work myself.”

Stonyfield Farms’ Hirshberg is a vehement supporter of the Non-GMO Project, but also believes that work must be done on Capitol Hill to convince lawmakers to mandate labeling, halt the introduction of new GE varieties, better contain those already out there, and compensate farmers when their crops are contaminated.

“A lot of the efforts out there are aimed at stopping GMOs altogether. That is not realistic. We are going to be living with these things with the rest of our lives whether we like it or not,” says Hirshberg, who was recently appointed to a trade and policy committee by President Barack Obama.  “The critical thing now is to maintain a back door—to have non-GM seeds preserved and to assure that consumers can continue to have a choice.”

Old-fashioned activism

Not everyone agrees with Hirshberg’s approach.

In a scathing blog post on the Organic Consumers Association website on Jan. 27, Ronnie Cummings named Stonyfield Farm, Organic Valley and Whole Foods Market  among “a self-appointed cabal of organic elite” and accused the company’s of “surrendering to Monsanto” by not fighting harder for an outright ban of genetically modified alfalfa. (According to The Organic Center’s Benbrook, the greatest threat posed by GE alfalfa is not the risk of GE contamination to the organic milk supply, but rather the contamination that could occur to alfalfa seed supply.)

“These companies have publicly admitted that they no longer oppose the mass commercialization of GE crops and are prepared to sit down and cut a deal for coexistence with Monsanto,” Cummings wrote. (The rant went on to call the Non-GMO Project a “greenwashing effort” that fails to put pressure on retailers and manufacturers to clean up their act.)

Although Cummings is also in favor of mandatory labeling laws, his organization is taking a different tack, staging rallies outside Whole Foods Markets, where protesters in white biohazard suits throw out “natural products” (including Tofutti, Kashi and Boca Burgers) believed to contain GM ingredients.

Their demand: Stop selling unlabeled GMO foods now.

If only it were so easy, says the Natural Grocery Co.’s Gerner. “I’d love to do that and I plan on doing it, but it will take years. We want to give manufacturers a chance to change their ways.”

In the meantime, Gerner and other retailers will continue to flag products with questionable ingredients, host lectures, support political efforts and attend industry meetings aimed at, essentially, trying to encourage everyone to get along.

Come October, regardless of their opinions on how the battle against GMOs should be waged, many of them will end up in the same place: on the East Coast, participating in the first ever Right to Know March to the U.S. Capitol.

“This is such a huge and important issue that we have to be coming at it from multiple angles and I really believe there is a place for all of it,” says Non-GMO Project Director Thomas, who is helping organize the two week protest march. “This is going to be a great chance to bring everyone together.”