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Essays Regarding Lack Ofresearch Testing Gmos

Is genetically engineered food dangerous? Many people seem to think it is. In the past five years, companies have submitted more than 27,000 products to the Non-GMO Project, which certifies goods that are free of genetically modified organisms. Last year, sales of such products nearly tripled. Whole Foods will soon require labels on all GMOs in its stores. Abbott, the company that makes Similac baby formula, has created a non-GMO version to give parents “peace of mind.” Trader Joe’s has sworn off GMOs. So has Chipotle.

Some environmentalists and public interest groups want to go further. Hundreds of organizations, including Consumers Union, Friends of the Earth, Physicians for Social Responsibility, the Center for Food Safety, and the Union of Concerned Scientists, are demanding “mandatory labeling of genetically engineered foods.” Since 2013, Vermont, Maine, and Connecticut have passed laws to require GMO labels. Massachusetts could be next.

The central premise of these laws—and the main source of consumer anxiety, which has sparked corporate interest in GMO-free food—is concern about health. Last year, in a survey by the Pew Research Center, 57 percent of Americans said it’s generally “unsafe to eat genetically modified foods.” Vermont says the primary purpose of its labeling law is to help people “avoid potential health risks of food produced from genetic engineering.” Chipotle notes that 300 scientists have “signed a statement rejecting the claim that there is a scientific consensus on the safety of GMOs for human consumption.” Until more studies are conducted, Chipotle says, “We believe it is prudent to take a cautious approach toward GMOs.”

I’ve spent much of the past year digging into the evidence. Here’s what I’ve learned. First, it’s true that the issue is complicated. But the deeper you dig, the more fraud you find in the case against GMOs. It’s full of errors, fallacies, misconceptions, misrepresentations, and lies. The people who tell you that Monsanto is hiding the truth are themselves hiding evidence that their own allegations about GMOs are false. They’re counting on you to feel overwhelmed by the science and to accept, as a gut presumption, their message of distrust.

A Slate Plus Special Feature:

In this members-only Slate Plus extra, Will Saletan reads his investigative study of the anti-GMO movement.

Second, the central argument of the anti-GMO movement—that prudence and caution are reasons to avoid genetically engineered, or GE, food—is a sham. Activists who tell you to play it safe around GMOs take no such care in evaluating the alternatives. They denounce proteins in GE crops as toxic, even as they defend drugs, pesticides, and non-GMO crops that are loaded with the same proteins. They portray genetic engineering as chaotic and unpredictable, even when studies indicate that other crop improvement methods, including those favored by the same activists, are more disruptive to plant genomes.

The deeper you dig, the more fraud you find in the case against GMOs.

Third, there are valid concerns about some aspects of GE agriculture, such as herbicides, monocultures, and patents. But none of these concerns is fundamentally about genetic engineering. Genetic engineering isn’t a thing. It’s a process that can be used in different ways to create different things. To think clearly about GMOs, you have to distinguish among the applications and focus on the substance of each case. If you’re concerned about pesticides and transparency, you need to know about the toxins to which your food has been exposed. A GMO label won’t tell you that. And it can lull you into buying a non-GMO product even when the GE alternative is safer.

If you’re like me, you don’t really want to wade into this issue. It’s too big, technical, and confusing. But come with me, just this once. I want to take you backstage, behind those blanket assurances about the safety of genetic engineering. I want to take you down into the details of four GMO fights, because that’s where you’ll find truth. You’ll come to the last curtain, the one that hides the reality of the anti-GMO movement. And you’ll see what’s behind it.

Twenty years ago Hawaiian papaya farmers were in trouble. Ringspot virus, transmitted by insects, was destroying the crop. Farmers tried everything to stop the virus: selective breeding, crop rotation, quarantine. Nothing worked. But one scientist had a different idea. What if he could transfer a gene from a harmless part of the virus, known as the coat protein, to the papaya’s DNA? Would the GE papaya be immune to the virus?

The scientist, Dennis Gonsalves of Cornell University, got the idea, in part, from Monsanto. But Monsanto wasn’t interested in papaya. Although papaya is an important staple in the developing world, it isn’t a big moneymaker like soybeans or cotton. So Monsanto and two other companies licensed the technology to an association of Hawaiian farmers. The licenses were free but restricted to Hawaii. The association provided the seeds to farmers for free, and later at cost.

Today the GE papaya is a triumph. It saved the industry. But it’s also a cautionary tale. The papaya, having defeated the virus, barely survived a campaign to purge GE crops from Hawaii. The story of that campaign teaches a hard lesson: No matter how long a GMO is eaten without harming anyone, and no matter how many studies are done to demonstrate its safety, there will always be skeptics who warn of unknown risks.

In 1996 and 1997, three federal agencies approved the GE papaya. The U.S. Department of Agriculture reported “no deleterious effects on plants, nontarget organisms, or the environment” in field trials. The Environmental Protection Agency pointed out that people had been eating the virus for years in infected papaya. “Entire infectious particles of Papaya Ringspot Virus, including the coat protein component, are found in the fruit, leaves and stems of most plants,” the EPA observed. The agency cited the

long history of mammalian consumption of the entire plant virus particle in foods, without causing any deleterious human health effects. Virus-infected plants currently are and have always been a part of both the human and domestic animal food supply and there have been no findings which indicate that plant viruses are toxic to humans and other vertebrates. Further, plant viruses are unable to replicate in mammals or other vertebrates, thereby eliminating the possibility of human infection.

These arguments didn’t satisfy everyone. In 1999, a year after the new papaya seeds were released to farmers, critics said the viral gene might interact with DNA from other viruses to create more dangerous pathogens. In 2000, vandals destroyed papaya trees and other biotech plants at a University of Hawaii research facility, calling the plants “genetic pollution.” In 2001 the U.S. Public Interest Research Group identified Hawaii as the state most commonly used for outdoor GE crop tests, and it called for a nationwide moratorium on such tests. “The science of genetic engineering is radical and new,” said U.S. PIRG, and GE crops had “not been properly tested for human health or environmental impact.”

Greenpeace vandals tore up a GE papaya orchard in Thailand, calling the plant a “time bomb.”

A Dutch study published in December 2002 seemed to vindicate this anxiety. According to the paper, a short stretch of the ringspot virus coat protein, now incorporated in the GE papaya, matched a sequence in an allergenic protein made by worms. The resemblance was only partial, and, as the authors noted, it didn’t show that the protein triggered allergies, much less that the papaya did so. But anti-GMO activists didn’t wait. The Institute of Science in Society published a “Biosafety Alert” titled “Allergenic GM Papaya Scandal.” Greenpeace flagged the Dutch study and warned that “the interaction of GE papaya with other viruses … can produce new strains of viruses.” The organization accused the papaya’s developers of “playing with nature.”

Some of these early alarms were disconcerting. But scientifically, they made no sense. Start with the distinction between “nature” and “genetic pollution.” Nature had invented the ringspot virus. Millions of people had eaten it without any reports of harm. And breeders had been tinkering with nature for millennia.

Anti-GMO activists decried genetic engineering as imprecise and random. They ignored the far greater randomness of mutation in nature and the far greater imprecision of traditional breeding. Furthermore, after five years of commercial sale and consumption, there was no sign that GE papayas had hurt anyone. But the alarmists continued to fret about unforeseen interactions and doomsday mutations, ignoring research that didn’t bear out these fantasies.

Take the “Allergenic GM Papaya Scandal.” The protein made by the papaya’s new gene consisted of about 280 amino acids. Out of that 280, the number of consecutive amino acids it shared with a putative allergen was six. By this standard, a study found that 41 of 50 randomly selected proteins in ordinary corn would also have to be declared allergenic. But GMO opponents ignored this study. They also ignored a second paper, which concluded that the putative worm allergen used in the papaya comparison was not, in fact, intrinsically allergenic.

Years passed, people ate papayas, and nothing bad happened. But the activists wouldn’t relent. In 2004, Greenpeace vandals tore up a GE papaya orchard in Thailand, calling the plant a “time bomb” and claiming that it had devastated farmers in Hawaii. In 2006, Greenpeace issued another report condemning the fruit. In reality, the source of farmers’ troubles was Greenpeace itself. The organization was working to block regulatory approval and sales of the GE papaya—and then blaming the papaya for farmers’ financial woes.

From 2006 to 2010, USDA scientists, prodded by Japanese regulators, subjected the papaya to several additional studies. They verified that its new protein had no genetic sequence in common with any known allergen, using the common standard of eight consecutive amino acids rather than six. They demonstrated that the protein, unlike allergens, broke down in seconds in gastric fluid. They found that conventional virus-infected papayas, which people had been eating all along, had eight times as much viral protein as the GE papaya. In May 2009, after a decade of scrutiny, Japan’s Food Safety Commission approved the GE papaya. Two years later, after resolving environmental questions, Japan opened its market to the fruit.

Chinese researchers performed additional tests. For four weeks they fed GE papayas to a group of rats. Meanwhile, they fed conventional papayas to another group of rats. The study found no resulting differences between the rats. It confirmed that coat protein fragments dissolved quickly in gastric fluid and left no detectable traces in organs.

By this point the GE papaya had been investigated and eaten for 15 years. GMO skeptics had two choices. They could acknowledge that their nightmares hadn’t come true. Or they could reject the evidence and cling to their faith in a GMO apocalypse.

That dilemma split the anti-GMO camp in 2013, when the Hawaii County Council, which governed Hawaii’s largest island, considered legislation to ban GE crops. The council’s hearings, preserved on video by Occupy Hawaii (which favored the proposed ban), document a yearlong struggle between ideology and science. As council members heard testimony and studied the issue, they learned that the GE papaya didn’t fit GMO stereotypes. It had been created by public-sector scientists, not by a corporation. It had saved a beloved crop. It had passed extensive scrutiny in Japan and the U.S. It didn’t cross-pollinate nearby fields. It also reduced pesticide use, because farmers no longer had to exterminate the aphids that spread the virus.

One council member, Margaret Wille, yielded to the evidence. Wille was Hawaii’s leading anti-GMO politician. She had introduced the proposed GMO ban. But after listening to the arguments, she exempted the GE papaya from her bill, noting that it was embedded in local agriculture and had been vetted in safety and cross-pollination tests. In effect, she acknowledged two things. First, the legitimate worries of biotech critics, such as pesticide use and corporate control of agriculture, didn’t apply to all GE crops. And second, with the passage of time, novelties became conventional.

Other antagonists held their ground. Chief among them was Jeffrey Smith, the world’s most prolific anti-GMO activist. In September 2013, Smith was given 45 minutes to testify before the council as an expert witness, though he had no formal scientific training. (When he was asked whether he should be addressed as Dr. Smith, he sidestepped the question by answering, “No, Jeffrey’s fine.”) Smith told the council that RNA from the GE papaya might disrupt genes in people and that proteins from the papaya might interfere with human immunity, leading to HIV and hepatitis. He also said the protein might cause cancer.

To support his testimony, Smith cited a March 2013 paper about regulation of GE crops. He said the paper “showed that the evaluation of this technology is sorely inadequate to protect against environmental problems and human health problems. And the papaya was one example cited in that study.” But the paper made no claim about papayas. It simply listed them in a table of GE crops, alongside a theoretical critique of the technology.

Smith told the council that “there hasn’t been any animal feeding studies on the papaya.” Hector Valenzuela, a University of Hawaii crop specialist who also testified as an expert, said the same thing: that scientists hadn’t “conducted a single study” to assess the safety of GE papaya. Neither man mentioned the Chinese papaya feeding study in rats—published two months before the theoretical paper Smith had cited—which had found none of the harms Smith alleged.

To explain why scientific organizations and regulatory agencies had declared GE foods safe, the anti-GMO witnesses offered conspiracy theories. They said the Food and Drug Administration had been captured by Monsanto. So had the American Association for the Advancement of Science. When the New York Times’ Pulitzer Prize-winning science reporter Amy Harmon detailed the safety evidence behind the GE papaya, incredulous council members dismissed her article as a “skewed” account by “the political powers that be.”

As for Japan’s approval of the papaya, Valenzuela advised the council to look at U.S. government cables released by WikiLeaks. He said the cables showed “the lengths that the State Department goes to twist arms behind the scenes.” This was a clear insinuation that U.S. officials had coerced Japan’s decision. Smith mentioned the cables, too. But the cables showed no conspiracy. Nearly 6,000 of the leaked cables had been sent from U.S. embassies and consulates in Japan. They covered the years 2005 to 2010, during which Japanese regulators had debated and approved the GE papaya. Food & Water Watch, an environmental group, had searched the cables for references to pressure or lobbying by U.S. officials on behalf of GMOs. The group’s report, issued in May 2013, cited no cables that indicated any such activity in Japan.

No allegation was too far-fetched for the anti-GMO witnesses, including several who called themselves experts. They said GMOs were especially dangerous to dark-skinned people. They suggested that vaccines were harmful, too. They said GE flowers should be banned because children might eat them.

What they wouldn’t say, regardless of the evidence, was that the GE papaya was safe. Brenda Ford, a council member and sponsor of another anti-GMO bill, told her colleagues that they didn’t have to answer that question, even when they were directly asked. Ford described genetic engineering as “random hits” on chromosomes. She said the science was still “in its infancy.” Smith, in his testimony, suggested that gene transfer in agriculture should be studied for 50 to 150 years before allowing its use outdoors.

In the end, the papaya survived. Ford’s bill died. Wille’s bill was signed into law but was tied up in court. The new law makes an exception for papayas. But GMO labels don’t. They don’t tell you that the fruit you’re looking at in your grocery store was engineered to need fewer pesticides, not more. They don’t tell you about all the research that went into checking its safety. They don’t tell you that people have been eating it with no ill effects for more than 15 years. They don’t tell you that when you buy it, your money goes to Hawaiian farmers, not to Monsanto.

Some people, to this day, believe GE papayas are dangerous. They want more studies. They’ll always want more studies. They call themselves skeptics. But when you cling to an unsubstantiated belief, even after two decades of research and experience, that’s not skepticism. It’s dogma.

In 1901 a Japanese biologist discovered that a strain of bacteria was killing his country’s silkworms. Scientists gave the bacteria a name: Bacillus thuringiensis. It turned out to be handy for protecting crops from insects. Farmers and environmentalists loved it. It was natural, effective, and harmless to vertebrates.

In the mid-1980s, Belgian researchers found a better way to produce the insecticide. They put a gene from the bacteria into tobacco plants. When bugs tried to eat the plants, they died. Now farmers wouldn’t need the bacteria. Plants that had the new gene, known as Bt, could produce the insecticidal protein on their own.

Environmentalists flipped. What upset them wasn’t the insecticide but the genetic engineering. Thus began the strange backlash against Bt crops. A protein that everyone had previously agreed was innocuous suddenly became a menace. To many critics of biotechnology, the long history of safe Bt use was irrelevant. What mattered was that Bt was now a GMO. And GMOs were evil.

In 1995 the EPA approved Bt potatoes, corn, and cotton. The agency noted that the toxin produced by these crops was “identical to that produced naturally in the bacterium” and “affects insects when ingested, but not mammals.” But opponents weren’t mollified. In 1999 a coalition led by Greenpeace, the Center for Food Safety, the Pesticide Action Network, and the International Federation of Organic Agriculture Movements sued the EPA to revoke its approvals. The suit said Bt crops might create insecticide-resistant insects and cause “direct harm to non-target organisms.”

The coalition claimed to speak for environmental caution. But its caution was curiously selective. Thirty of the 34 farmers who were identified in the lawsuit as victims and plaintiffs affirmed that they sprayed Bt on their own crops. Fourteen of the 16 farming organizations listed as plaintiffs said they had members who used Bt spray. One plaintiff, according to the lawsuit, was a “supplier of organic fertilizers and pest controls” whose business “consists of selling foliar Bt products to conventional apple growers.” Another was “one of the largest suppliers of beneficial insects and natural organisms designed to control agricultural pests,” including “several Bt products.”

Greenpeace and its partners weren’t fighting the Bt industry. They were protecting it. They were trying to convince the public that the Bt protein was dangerous when produced by plants but perfectly safe when produced by bacteria and sprayed by farmers.

The anti-GMO lobby says Bt crops are worse than Bt sprays, in part because Bt crops have too much of the bacterial toxin. In 2007, for instance, Greenpeace promoted a court petition to stop field trials of Bt eggplant in India. The petition told the country’s highest court, “The Bt toxin in GM crops is 1,000 times more concentrated than in Bt sprays.” But Greenpeace’s internal research belied that statement. A 2002 Greenpeace report, based on Chinese lab tests, found that the toxin level in Bt crops was severely “limited.” In 2006, when Greenpeace investigators examined Bt corn in Germany and Spain, they got a surprise: “The plants sampled showed in general very low Bt concentrations.”

An honest environmental organization, having discovered these low concentrations, might have reconsidered its opposition to Bt crops. But Greenpeace simply changed its rationale. Having argued in its 1999 lawsuit that Bt crops produced too much toxin, Greenpeace now reversed itself. In its report on the German and Spanish corn, the organization complained that Bt crops produced too little toxin to be effective. It argued, in essence, that the Bt in transgenic crops was unsafe for humans but insufficient to kill bugs.

Anti-GMO activists also claim that the insecticidal protein is “activated” in Bt crops but not in Bt sprays, and that this makes Bt crops more dangerous to people. That’s misleading. “Activation” just means that the protein is truncated, which helps it bind to the guts of insects. And each Bt plant is different. A global database of GE crops, maintained by the Center for Environmental Risk Assessment, shows that some Bt proteins are fully truncated while others are partially truncated. Even the fully truncated proteins are just “semi-activated,” according to a technical assessment that was sent to Greenpeace by its own consultants 15 years ago. Unless you’re a bug, Bt isn’t active.

In its 1999 lawsuit, Greenpeace said Bt crops were dangerous because their toxins were “not readily degraded in the environment.” The organization and its allies have repeated this allegation many times since. But when it’s convenient, Greenpeace says the opposite. Its 2006 petition to block Bt crops in New Zealand speculated that the concentration of toxin in Bt cotton might be too low “because the Bt protein is degraded, linked to heat stress.” The petition added that the plant’s defense mechanisms “may also reduce the insecticidal activity of Bt.”

In fact, the 2006 petition suggested that the low concentration of Bt in Indian cotton was allowing insects to flourish, leading to crop losses, and causing farmers to fall into debt and kill themselves. The suicide allegation was just another anti-GMO fiction. But it allowed Greenpeace to claim that the Bt in transgenic crops was killing people in two ways: by being more persistent and potent than the Bt in sprays, and by being less persistent and potent than the Bt in sprays.

The strangest part of the case against Bt crops is the putative evidence of harm. Numerous studies have found that Bt is one of the world’s safest pesticides. Still, if you run enough experiments on any pesticide, a few will produce correlations that look worrisome. But that’s just the first step in challenging a scientific consensus. Experts then debate whether the correlations are causal and whether the effects are important. They ask for better, controlled experiments to validate the pattern. That’s where the case against Bt crops and other GMOs has repeatedly failed.

But that isn’t what’s strange. What’s strange is that so much of the ostensible evidence against Bt crops is, at best, evidence against Bt sprays.

You can think you’re eating less Bt, when in fact you’re eating more.

In its 2006 petition to regulators in New Zealand, Greenpeace argued that Bt crops, by applying evolutionary pressure, would generate Bt-resistant insects, thereby depriving organic farmers of their rightful “use of Bt as a pesticide.” The petition also warned that the “Bt toxin can persist in soils for over 200 days” and that this “could cause problems for non-target organisms and the health of the soil ecosystem.” But two of the three experiments cited as evidence for the soil warning weren’t done with Bt crops. They were done with DiPel, a commercial Bt spray compound. Greenpeace was asking New Zealand to protect Bt spray from Bt crops based on studies that, if anything, indicted Bt spray.

The 2007 petition against Bt eggplant in India repeated this fallacy. “The natural bacterium Bt is very important in advanced organic agriculture,” said the petition. For this reason, it argued, the evolution of Bt-resistant insects due to Bt crops “would be a serious threat to many types of agriculture on which a country such as India inevitably & rightly relies.” But an addendum to the petition cited, as evidence of Bt’s perils, studies that were done with Javelin, Foray, and VectoBac—three Bt spray compounds.

This paradox pervades the anti-GMO movement: alarmism about any possibility of harm from Bt crops, coupled with relentless flacking for the Bt spray industry. “Farmers have always used Bt sparingly and usually as a last resort,” says the Organic Consumers Association. But that doesn’t square with the product literature for commercial Bt sprays. One brochure recommends “motorized boom sprayers” and says “aerial applications are also commonplace in many crops.” Another explains that “many avocado orchards are sprayed by helicopter.” Saturation is a point of emphasis: “Sprays should thoroughly cover all plant surfaces, even the undersides of leaves.”

Greenpeace says you needn’t worry, because “Bt proteins from natural Bt sprays degrade” within two weeks. But this is a false assurance, because farmers compensate for the degradation by reapplying the spray. A typical brochure recommends reapplication “every 5-7 days.” That’s plenty of time to get the toxin to your mouth, since the product literature tells growers that “ripe fruit can be picked and eaten the same day that it is sprayed.” In YouTube videos, organic farmers deliver the same instructions: You should spray your vegetables with Bt every four days, coating each surface, and you can eat the food right after you spray it.

Bt sprays, unlike Bt crops, include live bacteria, which can multiply in food. Several years ago researchers examined vegetables for sale in Denmark. They found 23 strains of Bt identical to the kind used in commercial sprays. In China a similar study of milk, ice cream, and green tea beverages found 19 Bt strains, five of them identical to the kind used in sprays. In Canada nasal swabs of people living inside and outside zones where Bt was being applied found the bacteria in 17 percent of samples taken before crops were sprayed, as well as 36 percent to 47 percent of samples taken afterward.

Nobody monitors how much Bt is applied worldwide. Last fall the Wall Street Journal estimated that annual sales of biopesticides were roughly $2 billion. Bt has been said to account for 57 percent to 90 percent of that market. In 2001, Bt was reportedly applied in the U.S. to more than 40 percent of tomatoes and 60 percent of brassica crops, which include broccoli, cauliflower, and cabbage. Since then, biopesticide sales have risen substantially. In Europe the annual growth rate since 2000 has been nearly 17 percent. Every market analysis predicts that biopesticides will grow at a much faster rate than the overall insecticide market, in part because governments are promoting them. The Journal projects that by 2020, 10 percent of global pesticide sales will be Bt and other biological formulas.

One result of this paradox—GMOs under attack, while biopesticides flourish—is that you can think you’re eating less Bt, when in fact you’re eating more. Suppose you live in Germany. According to a 2014 congressional research report, Germany has some of the world’s strictest GMO policies. It requires labels, discourages GMO cultivation, and has prohibited even some crops approved by the European Union. But U.N. data show that during the most recent 10-year reporting period, for every 1,000 hectares of arable German land, an annual average of 125 metric tons of biological and botanical pesticides (the category that includes Bt) were sold for agricultural use in crops and seeds. That works out to more than 100 pounds per acre per year. By comparison, no Bt corn variety produces more than 4 pounds of toxin per acre.

And guess who’s selling all that Bt: the same companies Greenpeace condemns for peddling chemical pesticides and GMOs. Since 2012 the top four companies on Greenpeace’s list of global pesticide villains—Monsanto, Syngenta, Bayer, and BASF—have spent about $2 billion to move into the biopesticide market. Another agrochemical giant, DuPont, has invested $6 billion. If you’re boycotting GMOs or buying organic to escape Bt and fight corporate agriculture, think again. Monsanto is one step ahead of you.

Anti-GMO zealots refuse to face the truth about Bt. Two years ago the Organic Consumers Association and its allied website GreenMedInfo published the headline “New Study Links GMO Food to Leukemia.” Today that headline remains uncorrected, even though the study was done with Bt spore crystals, which are components of Bt spray, not Bt crops. (The study is a mess. Most of what was fed to the test animals wasn’t Bt toxin, and the write-up, for undisclosed reasons, was withdrawn from an established journal and published instead in a journal that had never before existed.) Meanwhile, last year, Greenpeace published a catalog of “exemplary” agriculture, in which it celebrated a Spanish farm where “the use of Bacillus thuringiensis is being expanded to a greater cultivated surface area.” Both organizations encourage you to buy organic, neglecting to mention the dozens of Bt insecticides approved for use in organic agriculture.

GMO labels won’t clear this up. They won’t tell you whether there’s Bt in your food. They’ll only give you the illusion that you’ve escaped it. That’s one lesson of the Non-GMO Project, whose voluntary labels purport to give you an “informed choice” about what’s in your food. Earlier this year, Slate interns Natania Levy and Greer Prettyman contacted the manufacturers of 15 corn products bearing the Non-GMO Project label. They asked each company whether its product included any ingredients sprayed with biopesticides. Five companies didn’t reply. Two told us, falsely, that their organic certification meant they didn’t use pesticides or anything that could be harmful. One sent us weasel words and repeated them when we pressed for a clearer answer. Another told us it adhered to legal limits. Three confessed that they didn’t know. None of the manufacturers could give us a clear assurance that its product hadn’t been exposed to Bt.

That’s the fundamental flaw in the anti-GMO movement. It only pretends to inform you. When you push past its dogmas and examine the evidence, you realize that the movement’s fixation on genetic engineering has been an enormous mistake. The principles it claims to stand for—environmental protection, public health, community agriculture—are better served by considering the facts of each case than by treating GMOs, categorically, as a proxy for all that’s wrong with the world. That’s the truth, in all its messy complexity. Too bad it won’t fit on a label.

Right now, across the world, a quarter of a billion preschool-age children are suffering from vitamin A deficiency. Every year, 250,000 to 500,000 of these kids go blind. Within a year, half of the blinded children will die. Much of the affliction is in Southeast Asia, where people rely on rice for their nutrition. Rice doesn’t have enough beta carotene—the compound that, when digested, produces vitamin A.

Twenty-five years ago, a team of scientists, led by Ingo Potrykus of the Swiss Federal Institute of Technology, set out to solve this problem. Their plan was to engineer a new kind of rice that would make beta carotene.

The idea sounded crazy. But to Potrykus it made more sense than what some governments were already doing: giving each person two high-dose vitamin A pills a year. Wouldn’t it be smarter to embed beta carotene in the region’s staple crop? That way, people could grow the nutrient and eat it every day, instead of relying on occasional handouts. This was a sustainable solution. It would use biotechnology to prevent suffering, disability, and death.

In 1999, Potrykus and his colleagues achieved their first breakthrough. By transferring genes from daffodils and bacteria, they created the world’s first beta carotene rice. The yellow grains became known as “Golden Rice.” President Clinton celebrated the achievement and urged GMO skeptics to do the same. He acknowledged that genetic engineering “tends to be treated as an issue of the interest of the agribusiness companies, and earning big profits, against food safety.” But in the case of vitamin A deficiency, the greater risk to health lay in doing nothing. “If we could get more of this Golden Rice … out to the develop[ing] world,” said Clinton, “it could save 40,000 lives a day.”

Anti-GMO groups were confounded. This humanitarian project undermined their usual objections to genetic engineering. In 2001, Benedikt Haerlin, Greenpeace’s anti-GMO coordinator, appeared with Potrykus at a press conference in France. Haerlin conceded that Golden Rice served “a good purpose” and posed “a moral challenge to our position.” Greenpeace couldn’t dismiss the rice as poison. So it opposed the project on technical grounds: Golden Rice didn’t produce enough beta carotene.

The better approach, according to biotechnology critics, was to help people cultivate home gardens full of beans, pumpkins, and other crops rich in Vitamin A. Where that wasn’t feasible or sufficient, Greenpeace recommended supplementation (distributing vitamin A pills) or food fortification, by mixing vitamin A into centrally processed ingredients such as sugar, flour, and margarine.

Greenpeace was right about Golden Rice. At the time, the rice didn’t provide enough beta carotene to cure vitamin A deficiency. But neither did the alternatives. Gordon Conway, the president of the Rockefeller Foundation, which was funding the project, explained some of the difficulties in a 2001 letter to Greenpeace:

Complete balanced diets are the best solution, but the poorer families are, the less likely it is that their children will receive a balanced diet and the more likely they will be dependent on cheap food staples such as rice. This is particularly true in the dry seasons when fruits and vegetables are in short supply and expensive.

Conway echoed the skepticism of UNICEF nutritionists, who doubted that plants native to the afflicted countries could deliver enough digestible beta carotene. To Potrykus, the notion of home gardens for everyone—Let them eat carrot cake—reeked of Western ignorance. “There are hundreds of millions of landless poor,” Potrykus pointed out. “They don’t have a house to lean the fruit tree against.”

Potrykus and Conway wanted to try everything to alleviate vitamin A deficiency: diversification, fortification, supplementation, and Golden Rice. But the anti-GMO groups refused. They called Golden Rice a “Trojan horse” for genetic engineering. They doubled down on their double standards. They claimed that people in the afflicted countries wouldn’t eat yellow rice, yet somehow could be taught to grow unfamiliar vegetables. They portrayed Golden Rice as a financial scheme, but then—after Potrykus made clear that it would be given to poor farmers for free—objected that free distribution would lead to genetic contamination of local crops. Some anti-GMO groups said the rice should be abandoned because it was tied up in 70 patents. Others said the claim of 70 patents was a fiction devised by the project’s leaders to justify their collaboration with AstraZeneca, a global corporation.

While critics tried to block the project, Potrykus and his colleagues worked to improve the rice. By 2003 they had developed plants with eight times as much beta carotene as the original version. In 2005 they unveiled a line that had 20 times as much beta carotene as the original. GMO critics could no longer dismiss Golden Rice as inadequate. So they reversed course. Now that the rice produced plenty of beta carotene, anti-GMO activists claimed that beta carotene and vitamin A were dangerous.

In 2001, Friends of the Earth had scoffed that Golden Rice would “do little to ameliorate VAD [vitamin A deficiency] because it produces so little beta-carotene.” By November 2004 the group had changed its tune. Crops that yielded beta carotene could “cause direct toxicity or abnormal embryonic development,” it asserted. Another anti-GMO lobby, the Institute of Science in Society, documented its own shift in a 2006 report:

ISIS critically reviewed golden rice in 2000. Among the observations was that the rice produced too little beta-carotene to relieve the existing dietary deficiency. Since then, golden rice strains have been improved, but still fall short of relieving dietary deficiency. On the other hand, increasing the level of beta-carotene may cause vitamin A overdose to those [whose] diets provide adequate amounts of the vitamin. In fact, both vitamin A deficiency and supplementation may cause birth defects.

To support the new alarmism, David Schubert, an anti-GMO activist and neurobiologist at the Salk Institute, drafted a paper on the ostensible perils of boosting vitamin A. In 2008 he got it published in the Journal of Medicinal Food. In the article he noted that beta carotene and dozens of related compounds, known as carotenoids, could produce other compounds, called retinoids, which included vitamin A. He declared that all retinoids “are likely to be teratogenic”—prone to causing birth defects—and, therefore, “extensive safety testing should be required before the introduction of golden rice.”

David Schubert gave opponents of Golden Rice what they needed: the illusion of scientific support.

Schubert systematically distorted the evidence. To suggest that Golden Rice might be toxic, he cited a study that had been reported in the New England Journal of Medicine in 1994. Schubert said the study found that “smokers who supplemented their diet with beta-carotene had an increased risk of lung cancer.” He neglected to mention that the daily beta carotene dose administered in the study was the equivalent of roughly 10 to 20 bowls of Golden Rice. He also failed to quote the rest of the paper, which emphasized that in general, beta carotene was actually associated with a lower risk of lung cancer. Furthermore, he claimed that a 2004 report by the National Research Council said genetic engineering had “a higher probability of producing unanticipated changes than some genetic modification methods.” In reality, the NRC report said genetic engineering

has a higher probability of producing unanticipated changes than some genetic modification methods, such as narrow crosses, and a lower probability than others, such as radiation mutagenesis. Therefore, the nature of the compositional change merits greater consideration than the method used to achieve the change.

By omitting the second half of the sentence—“and a lower probability than others”—Schubert made the NRC report appear to raise alarms about GMOs, when in fact the report had explained why alarmism about GMOs was wrongheaded.

Schubert gave opponents of Golden Rice what they needed: the illusion of scientific support. Every anti-GMO lobby cited his paper. The movement’s new position, as expressed by Ban GM Food, was that “Golden Rice is engineered to overproduce beta carotene, and studies show that some retinoids derived from beta carotene are toxic and cause birth defects.”

But the new position, like the old one, relied on double standards. To begin with, every green plant produces carotenoids. For years, anti-GMO groups had argued that instead of eating Golden Rice, people should grow other plants rich in beta carotene. They had also encouraged the use of selective breeding to increase carotenoid levels. If carotenoids were toxic, wouldn’t these plants deliver the same poison?

GMO critics didn’t seem to care how much beta carotene people ate, as long as the food wasn’t genetically engineered. They demanded extra safety tests on Golden Rice, on the grounds that “large doses of beta-carotene can have negative health effects.” But they shrugged off such vigilance in the case of home gardens, saying it was “not necessary to count the amount” of each vitamin consumed. They also advocated the mass administration of vitamin A through high-dose capsules and chemical manipulation of the food supply. By their own alarmist standards—which, fortunately, were unwarranted—this would have been reckless. The human body derives from beta carotene sources, such as Golden Rice, only as much vitamin A as it needs.

In the context of GMOs, Greenpeace claimed to stand for freedom. Its 2009 statement “Hands off our rice!” said “keeping rice GE-free” was an issue of “consumer choice” and “human rights.” The statement complained that GE rice was “controlled by multinational corporations and governments” and “severely limits the choice of food we can eat.” But as long as GMOs weren’t involved, Greenpeace was all for corporate and government control. It lauded the distribution of vitamin A and beta carotene capsules in “mass immunization campaigns.” It praised health officials and food-processing companies for putting vitamin A and beta carotene in sugar, margarine, and biscuits. It suggested that governments could “make fortification compulsory.”

In the Philippines, where Greenpeace was fighting to block field trials of Golden Rice, its hypocrisy was egregious. “It is irresponsible to impose GE 'Golden' rice on people if it goes against their religious beliefs, cultural heritage and sense of identity, or simply because they do not want it,” Greenpeace declared. But just below that pronouncement, Greenpeace recommended “vitamin A supplementation and vitamin fortification of foods as successfully implemented in the Philippines.” Under Philippine law, beta carotene and vitamin A had to be added to sugar, flour, and cooking oil prior to distribution. The government administered capsules to preschoolers twice a year, and to some pregnant women for 28 consecutive days. If Greenpeace seriously believed that retinoids caused birth defects and should be a matter of personal choice, it would never have endorsed these programs.

Despite this, the anti-GMO lobby went ballistic when scientists fed Golden Rice to 24 children during clinical trials in China. The trials, conducted in 2008, were designed to measure how much vitamin A the rice could generate in people who suffered from vitamin A deficiency. One group of kids was given Golden Rice, a second group was given beta carotene capsules, and a third was given spinach. The researchers found that a single serving of Golden Rice, cooked from 50 grams of grains, could supply 60 percent of a child’s recommended daily intake of vitamin A. In a separate study, they found that an adult-sized serving could do the same for adults. Golden Rice was as good as capsules, and better than spinach, at delivering vitamin A.

When Greenpeace found out about the trials, it enlisted the Chinese government to stop them. It accused the researchers of using the kids as “guinea pigs.” In a letter to Tufts University, which was responsible for the trials, Schubert and 20 other anti-GMO scientists protested:

Our greatest concern is that this rice, which is engineered to overproduce beta carotene, has never been tested in animals, and there is an extensive medical literature showing that retinoids that can be derived from beta carotene are both toxic and cause birth defects. 

In these circumstances the use of human subjects (including children who are already suffering illness as a result of Vitamin A deficiency) for GM feeding experiments is completely unacceptable.

For all the scare talk about beta carotene, Schubert and his colleagues never mentioned the kids who were given beta carotene capsules in the studies. Nor did Greenpeace. Their sole concern was the rice.

Supporters of Golden Rice were baffled. In a letter to the Daily Mail, six scientists wrote, “The experiments were no more dangerous than feeding the children a small carrot since the levels of beta-carotene and related compounds in Golden Rice are similar.” But anti-GMO groups were determined to discredit the studies. They discovered that although the consent forms given to the children’s parents said Golden Rice “makes beta carotene,” the forms didn’t specify that this had been achieved through gene transfer.

Greenpeace was outraged. Its press release titled “Greenpeace alarmed at US-backed GMO experiments on children” quoted a Greenpeace official in Asia: “The next ‘golden rice’ guinea pigs might be Filipino children. Should we allow ourselves to be subjects in a human experiment?” In another press release, Greenpeace questioned whether the Chinese parents were “properly informed of the risks.” Yet in the same statements, Greenpeace praised the Philippines for administering vitamin A to pregnant women and for putting beta carotene in the food supply.

Eventually, Tufts commissioned three reviews of the clinical trials. Two were internal; the third was external. The findings, released in 2013, confirmed that the reviews had “identified concerns” about “inadequate explanation of the genetically-modified nature of Golden Rice.” But the more important verdict was that “the study data were validated and no health or safety concerns were identified.” The university explained:

These multiple reviews found no concerns related to the integrity of the study data, the accuracy of the research results or the safety of the research subjects. In fact, the study indicated that a single serving of the test product, Golden Rice, could provide greater than 50 percent of the recommended daily intake of vitamin A in these children, which could significantly improve health outcomes if adopted as a dietary regimen.

This verdict didn’t suit opponents of Golden Rice. So they ignored it. For 16 years they’ve ignored every fact or finding that doesn’t fit their story. Their enmity is unappeasable; their alarmism is unfalsifiable. Take the question of allergies. In 2006, scientists found no allergens among the proteins in Golden Rice. The critics refused to accept this finding. They demanded additional tests. They said climate change could undermine the rice’s “genetic stability.” They claimed that unforeseen environmental interactions could cause unintended changes in the rice after several generations, and therefore, regulators should indefinitely delay its approval.

The critics openly advocate unattainable standards. ISIS says the “instability of transgenic lines” makes “proper safety assessment well nigh impossible.” Greenpeace says of Golden Rice:

It would not be a surprise if additional unexpected changes in the plant occurred, posing new risks to the environment or human health. … However, it is virtually impossible to look for unexpected effects—by definition, one cannot know what these effects might be, or where to look for them!

And these standards apply only to GMOs. They don’t apply to alternatives favored by the anti-GMO movement. Three years ago Greenpeace recommended marker-assisted selection—essentially, breeding guided by genetic analysis—as a better way to increase levels of beta carotene and other nutrients. One argument quoted in the Greenpeace report was that genetic engineering caused “unpredictable integration sites, copy numbers and often spontaneous rearrangements and losses”—in short, that it screwed up the DNA of the altered organism. Shortly afterward, a study found that Greenpeace had it backward: In rice, marker-assisted selection caused

Mark Lynas is a well known example of this in the UK, with an (in)famous public apology for his past role in the anti-GM movement that drew a lot of media attention. This entry-point has proven quite attractive to the media, and Lynas' move has been copied by others, like blogger Stijn Bruers in Belgium. However, it is not clear why specifically these people are seen to have the credentials to merit this attention.

There are many fundamental flaws in the argumentation they are putting forward. Claire Robinson of GMWatch, at the request of Corporate Europe Observatory, has written a rebuttal of many of the claims made by these newly converted GMO proponents. For practical reasons, this rebuttal follows the argumentation and claims made in an article by Bruers on his blog about GMOs . [Author: Claire Robinson, November 2015]

1. GMO foods and crops pose health risks

Scientific organisations

Stijn Bruers' article starts with an appeal to authority in claiming GMOs are safe, that doesn’t stand up to scrutiny. He cites a number of respected scientific organisations, including the American Association for the Advancement of Science, the American Medical Association, and the United States National Academy of Sciences, which, he implies, concur that GMOs are safe.

The problem with this argument is that over 160 expert organisations have variously stated ( that GMOs have not been proven safe, and/or have supported mandatory GMO labelling.

For example:

The IAASTD report on the future of farming, co-authored by over 400 international experts and sponsored by the UN and World Bank, concluded ( “The safety of GMO foods and feed is controversial due to limited available data, particularly for long-term nutritional consumption and chronic exposure. Food safety is a major issue in the GMO debate… The concepts and techniques used for evaluating food and feed safety have been outlined… but the approval process of GM crops is considered inadequate.”

The Royal Society of Canada (RSC) criticized ( the internationally widespread use of the concept of “substantial equivalence” as a tool to exempt GM agricultural products from rigorous scientific assessment. It said that this practice (which dominates GMO regulation in Europe, where it is called “comparative assessment”, as well as other countries) is “scientifically unjustifiable and inconsistent with precautionary regulation of the technology”. The RSC added that the “default prediction” for every GM food should be that the introduction of a new gene would cause unanticipated changes, such as the production of new allergens.

The British Medical Association concluded (, “many unanswered questions remain… with regard to the potential long-term impact of GM foods on human health and on the environment.”

Bruers cites the position of the American Association for the Advancement of Science (AAAS) as evidence of GMO safety. It’s true that in 2012 the board of the AAAS, headed by GMO promoter Nina Fedoroff, issued a statement ( claiming GM was “safe” and opposing the mandatory labelling of GM foods in the US, which it said “can only serve to mislead and falsely alarm consumers”.

But Bruers fails to mention that the statement was promptly condemned ( by 21 scientists, including many members of the AAAS, as “an Orwellian argument that violates the right of consumers to make informed decisions”. And subsequently Fedoroff was revealed ( by emails disclosed as a result of freedom of information requests to be working hand-in-hand with the GMO industry to promote its products.

Bruers implies that the World Health Organization believes GMOs are safe. But this is false. The WHO has indeed stated ( “No effects on human health have been shown as a result of the consumption of GM foods.” But no health monitoring of people eating GM foods has ever been carried out – so it is not possible for health effects to be seen. What is known is that the health of people in the USA has worsened ( markedly since GM foods were introduced there in the mid-1990s. GM foods are not labelled there, so no one knows if there is a link with GM foods. But such a link cannot be ruled out.

Bruers carefully avoids quoting the context of the WHO statement. The WHO went on to say (, “Individual GM foods and their safety should be assessed on a case-by-case basis… it is not possible to make general statements on the safety of all GM foods.” This is a statement with which many opponents of GM foods would agree.

Bruers also misrepresents the position of the American Medical Association (AMA). In fact the AMA is a critic of the current GMO regulatory system in the USA, calling on ( the US Food and Drug Administration to require “pre-market systemic safety assessments of these [GM] foods as a preventive measure to ensure the health of the public.” Yet currently, there is no mandatory pre-market safety testing or assessment in the USA for GM food – only a voluntary consultation ( in which the FDA looks at whatever data the company wishes to provide and states that the company – not the FDA – may be liable if it puts unsafe food onto the market. The US EPA and USDA only involve ( themselves in the assessment process insofar as they judge the GMO to be a pesticide (as in the case of Bt crops) or a plant pest, and their oversight and requirements are minimal.

Often-cited “review studies” on 'GMO safety' and 'reduction of pesticide use'

Bruers cites two “major review studies” that converted him to the cause of GMOs:

A review by Nicolia and colleagues (2014) of 1783 articles on GM crop safety research, which claimed ( to find no “significant hazards” connected with such crops.

The meta-analysis by Klümper and Qaim (2014), which claimed ( a 37% reduction in chemical pesticide use from GM crops overall and a 42% reduction from Bt insecticidal crops (in which the insect-killing toxin is engineered into the plant). (See section on pesticide use).

However, these reviews mislead readers. They offer no grounds for reassurance about pesticide use on GM crops or about GMO safety – and the second actually provides evidence of GMO hazards. A detailed analysis follows.

  • Nicolia and colleagues’ (2014) conclusions on GMO safety

The review by Nicolia and colleagues cited by Bruers is widely used to argue that over 1700 studies show GM foods and crops are safe. However, the studies cited in the Nicolia review and supplementary materials, taken as a whole, do not show that GMOs are safe and some of the studies provide evidence of risk or actual harm from GMOs.

The majority of the articles in the list of 1700 are irrelevant or tangential to assessing the safety of commercialized GM foods and crops for human and animal health and the environment. The list contains many animal production studies, often performed by GM companies on their own products. These do not examine in detail the health impacts of GM feed but look at aspects of animal production of interest to the food and agriculture industry, such as weight gain and milk production.

While such studies provide the agriculture industry with useful information about whether an animal fed on the GMO will survive to slaughter age and deliver an acceptable meat or dairy product, they are usually short-term in comparison to the animal’s natural lifespan and provide no detailed information about the health of the animal.

Many of these studies are performed on animals such as cows, fish, and chickens. The digestive systems and metabolic functioning of these animals differ significantly from those of humans. Thus these studies are unlikely to provide useful information on human health risks.

The list includes some studies that are relevant to GMO safety and show actual or potential hazards of the GMO to health or the environment. The Nicolia review authors ignore or dismiss these findings without sound scientific justification. They also ignore evidence contradicting key assumptions upon which regulators have based their conclusions that GMOs are safe and major controversies over the interpretation of scientific findings on GMOs.

Nicolia and colleagues also omit important studies that demonstrate hazards related to GMOs. They use unscientific justifications for ignoring or dismissing important papers, including their arbitrary decision to include only studies published in the ten years since 2002.

Assembling questionable “Big Lists of Studies” supposedly providing evidence of the safety of GMOs has become common practice by GMO proponents. The aim of the practice is not to open scientific debate but to close it down ( But in the long term it will have a corrosive effect on public trust in science.

A detailed and fully referenced analysis of the Nicolia review, detailing all the points made above, has been published in the report, GMO Myths and Truths ( The report also summarizes many studies showing known hazards and potential risks of GM crops and foods.

A comprehensive list of over 1800 scientific studies and articles indicating hazards and uncertainties relating to GM crops and their associated pesticides has been assembled ( by the NGO, GMO Free USA.

All those who consult and use “Big Lists of Studies” on either side of the debate should form their own conclusions by actually reading the studies cited. More on the “Big lists”: see Annex I.

No scientific consensus on GMO safety - continued

There is no scientific consensus on GMO safety. A statement attesting to this fact, ( signed by over 300 well-qualified scientists, cites comprehensive reviews of numerous animal feeding studies that cast doubt on GMO safety. The statement concluded, “Claims of consensus on the safety of GMOs are not supported by an objective analysis of the refereed literature.”

Contrary to Bruers’s implication, animal feeding studies finding toxic effects and signs of toxicity are not restricted to the two studies led by Gilles-Eric Séralini and Judy Carman.

For example:

Dona and Arvanitoyannis (2009) concluded (, “The results of most studies with GM foods indicate that they may cause some common toxic effects such as hepatic, pancreatic, renal, or reproductive effects and may alter the hematological, biochemical, and immunologic parameters.”

A 2015 review highlighted 26 animal feeding studies showing harmful or potentially harmful effects of GM foods and concluded ( that unless and until these studies are replicated and shown to indicate false positives, “The putative consensus about the inherent safety of transgenic crops is premature.”

A factor that fuels scientific concern about GMO food safety is the relative rarity of controlled long-term animal feeding studies on commercialized GM crops. In 2012, in the wake of the Séralini study, which found ( toxic effects in liver and kidney and hormonal disruption from GM maize and Roundup fed to rats over a long-term period, the French food safety agency ANSES conducted a search for comparable long-term studies on glyphosate-tolerant GM crops, which make up over 80% of all commercialized GM crops worldwide. ANSES found ( only two studies.

One of these studies found ( toxic effects from feeding GM soy to mice. The other, by Japanese researchers, found no significant effects from the GM soy fed to rats. However, the researchers appear to have fed ( GM soy that was not sprayed with Roundup during cultivation, since glyphosate residues were not detected in the soy.

This absence of glyphosate residues in the GM soy in the Japanese study runs contrary to the findings ( of analytical tests ( of GM soy on the market. The first ( of these two analyses found ( levels of residues that are so high that Monsanto previously called them “extreme”, while the second ( found levels that are above regulatory levels deemed safe.

The Japanese study therefore is unlikely to reflect real-world farming practices.

In conclusion, out of three long-term feeding studies with glyphosate-tolerant GM crops, two found toxic effects and the other appears to have tested irrelevant material.

No consensus on GMO safety among medical scientists

Bruers states: “There is no strong evidence that current GM crops are less healthy than conventional crops. There is a strong consensus among medical scientists that GM crops do not pose a greater threat than conventional crops. The safety tests on GMOs are usually stricter than for new crops with conventional plant breeding techniques, and it seems that is no reason to do so. The scientific consensus is based on hundreds of independent studies that have no conflicts of interest and not sponsored by the GMO industry. About half of the GMO studies independently. (A number of studies indicating risks of GMOs – eg those by Gilles-Eric Séralini – were funded by environmental organizations). Unfortunately, unreliable, pseudo-scientific studies are still often cited. Thus, a petition article that casts the scientific consensus in doubt refers to the rat experiments by Gilles-Eric Séralini and the pig experiments by Judy Carman. That petition article was signed by more than 300 researchers, but the infamous Oregon Global Warming Petition Project was also signed by several hundred climate skeptic scientists.”

This statement is full of inaccurate claims that will be addressed below and in the next sections.

There does not appear to be any evidence to support Bruers’s specific claim of a consensus among “medical scientists” that GM crops are as safe as conventional crops. On the contrary, organisations ( of health professionals have critiqued current GMO safety assessments, issued warnings about GMO safety, and/or called for mandatory GMO labelling. For example:

The British Medical Association has expressed a warning ( about the “many unanswered questions” about the long-term effects of GMOs on health and the environment.

The American Medical Association has called on ( the US Food and Drug Administration to require “pre-market systemic safety assessments of these [GM] foods as a preventive measure to ensure the health of the public” – yet such assessments are not performed in the US.

The American Public Health Association (APHA) supports ( GMO labelling, citing “concerns related to human exposure to and consumption of these [GMO] plant proteins”.

The Public Health Association of Australia has called ( for long-term animal safety studies with GM foods, GMO labelling, and surveillance systems to monitor for possible effects of GM foods on health. Such long-term studies are not required by any regulator in the world and surveillance systems for health effects do not exist anywhere.

The Bundesärztekammer (German Medical Association) has called ( for mandatory GMO labelling, as health risks “cannot be ruled out”.

Surveys of medical and health professionals contradict Bruers’s assertion of a consensus among medical scientists that GMOs are safe.

In a 2013 survey ( of 200 medical doctors, 80.5% of the participants believed that GM foods are harmful. The authors of the published paper on the survey added, “In a similar study conducted by Engin et al., the said ratio was 66.7%. Kocak et al. conducted a study among medical faculty students and found that the ratio of those not consuming GMO foods was 54.4%.”

In a 2012 survey (!etd.send_file?accession=kent1353297827&disposi...) of 284 registered dietitians, 29.4% of those surveyed believed that “GM foods are completely safe to eat”, while 30% disagreed. The survey also determined that the more knowledgeable a dietitian was on GMO, the more likely they were to oppose GMO usage. When given the statement, “Scientists cannot predict future outcomes of genetically modified foods,” 60.5% agreed.

In conclusion, Bruers’s claim of a medical scientists’ consensus on GMO safety is false.

Industry bias in favour of GMO safety

Does it matter when GMO safety studies are funded and carried out by industry? Yes, because there is evidence that industry-linked studies are biased in favour of a conclusion of safety:

A review of 94 published studies on health risks and nutritional value of GM crops found ( that they were much more likely to reach favourable conclusions when the authors were affiliated with the GM industry than when the authors had no industry affiliation. In the studies where there was such a conflict of interest, 100% (41 out of 41) reached a favourable conclusion on GMO safety. The remaining 53 papers, in which none of the authors had professional ties to the biotech industry, were split: 39 concluded safety, 12 found problems, and two had neutral conclusions. This finding suggests that if a study on GMOs involves an industry scientist, it will invariably find no problem with the GMO.

A literature review of GM food safety studies found ( about an equal number of research groups suggesting that GM foods were safe and groups raising serious concerns. However, the authors commented that most studies concluding that GM foods are as nutritious and safe as non-GM counterparts were performed by the companies responsible for developing the GMO or associates.

A review of 15 published animal feeding studies with glyphosate-tolerant GM crops examined 6 studies by researchers with an industry affiliation and 9 by independent researchers. The review found ( that all 6 industry studies and 1 independent study found no significant effects from the GM feed; but the remaining 8 independent studies did find significant effects from the GM feed.

GMO risk research funding

Bruers says, “A number of studies indicating risks of GMOs – e.g. those by Gilles-Eric Séralini – were funded by environmental organizations”.

In order to balance the scientific evidence base on GM crops, funding for GMO risk research should be available to independent scientists – but it is notoriously hard to get. Companies and most governments are not motivated to pursue such research. Only one country in the world – Norway – has a research organization that is dedicated to looking at GMO risks. It may be no coincidence that Norway does not have an agribusiness lobby.

While study funding should always be scrutinized for conflicts of interest, there is no greater conflict of interest than the manufacturer/developer of a product sponsoring and controlling the safety research on its own product – which is the situation with GMOs and pesticides. These products are approved on the basis of studies commissioned by the manufacturer. In the case of pesticides, the studies are kept hidden from the public and independent scientists and so cannot be examined.

It is the stated mission of every company to maximize its profits; to do so is its duty to its shareholders. Environmental organizations that sponsor studies also have an interest, normally protection of public health and the environment. Which interest is likely to fatally undermine the veracity of a study – the imperative to sell product, or the desire to protect health and the environment? The answer should be clear.

There are many ways for a company to manipulate a study and its findings in order to show a “false negative” – in other words, to conclude that there is “no effect” even when a toxic effect exists. Methods include: making an animal feeding study duration too short to show long-term effects; making the sample size too small to get statistical significance in findings of harm; choosing an animal known to be insensitive to the substance under test; dismissing statistically significant differences in the test animals as biologically irrelevant, etc. Such shortcomings can produce “false negatives”, when an effect exists but is not found, or is claimed not to be found.

But it is much harder to produce a “false positive”, to come up with a finding that the substance does harm when in fact it is harmless. Yet this is what Bruers appears to suggest could be done by an environmental organization that wanted to skew a study outcome.

It is unclear how (for example) a finding that a substance caused liver or kidney pathologies in a higher number of animals could be invented out of nothing.

Is Bruers alleging that scientists whose research is sponsored by an environmental organization would lie about the number of animals that had that pathology in the various test groups? Does he really believe this, even though the scientists involved in the research are putting their names to the study and publishing it for all to see – and potentially replicate? And even though in many (perhaps most) cases, the pathologist that examines and reports on the disease state of the animal tissues is blinded to whether the tissue is from a control or test group?

Bruers should also ask himself whether any environmental organization would want to risk attaching its name to a fraudulent study by leaning on the researchers to skew the results. What would be its motivation, since the profit motive that leads companies and/or their sponsored researchers to engage in fraudulent ( science would be absent in this case?

Judy Carman pig study

Bruers attacks Dr Judy Carman and colleagues’ peer-reviewed experimental study, which found higher rates of severe stomach inflammation and heavier uteri in pigs fed GM feed compared with pigs fed non-GM feed. He does this not by referring to contradictory experimental findings, or even to a peer-reviewed article, but to a blog post ( attacking the paper, written by the pro-GMO campaigner Mark Lynas. As evidence for his attack on Carman’s paper, Lynas refers to a blog post by the agronomist Andrew Kniss ( Lynas praises Kniss for his use of an “appropriate statistical technique”.

The editors of the website GMOJudyCarman have replied ( to Kniss’s piece:

“In his blog (, Andrew Kniss professes to know more about statistics than the authors of the paper, even though between them, two of the authors of the paper have 45 years experience in using and teaching statistics at a university level. They have expertise in agricultural, toxicological, medical and epidemiological statistics.”

The editors go on to explain in detail why Kniss has “failed kindergarten-level statistics”. This perhaps explains why Kniss has not published his critiques in a peer-reviewed journal.

Lynas believes ( that Carman should have emphasized the heart and liver abnormalities, which were higher in non-GM-fed pigs than GM-fed pigs. However, they were analyzed by the authors and found not to be statistically significant (the analyses are presented in the paper), which is why they were not discussed.

Are those who question GMO safety equivalent to climate science deniers?

Bruers goes as far as copying Lynas and others in their very misplaced comparison of those who question the safety of GMOs to “the climate deniers who oppose the IPCC and many other scientific bodies.” This is a dishonest and inaccurate PR trick.

Corporate lobbyists’ attempts to convince the public that manmade climate change isn’t happening, and that GMOs are safe, suit their economic agenda but are scientifically indefensible. Generalised claims of GMO safety are “tobacco science” all over again. The main difference between GMO risk research and rigorous climate science is that there is very little funding available for the former.

If someone wishes to argue that the scientists arguing that GMOs have not been proven safe are a mistaken minority, the scientifically valid next step is to read the peer-reviewed studies showing GMO risks (for example, those cited by Krimsky, 2015; Hilbeck and colleagues, 2015; or in the publication, GMO Myths and Truths, and provide a scientific response, based on hard experimental data, to each point of evidence presented.

Ironically, by the way, many climate science deniers are also notable promoters of GMOs, such as the former UK environment minister Owen Paterson ( and and the pro-corporate lobbyist Patrick Moore ( and

2. GMOs good for the environment, reduce the use of pesticides?

The second review study cited by Bruers is one by Klümper and Qaim, claiming that GM crop cultivation has led to reduced pesticide use, particularly in Bt crops that produce their own insecticide.

However, these claims were shown to be baseless by a study ( by Douglas and Tooker (2015). Douglas and Tooker showed that the use of neonicotinoid insecticides on the major US crops subject to GM – corn and soy – expanded dramatically between 2003 and 2011. But Klümper and Qaim’s study was blind ( to this massive increase because the neonicotinoid insecticides were not sprayed onto the growing crop but coated onto the seeds before planting. Klümper and Qaim simply failed to consider insecticidal seed coatings in their calculations. While neonic seed coatings are used on both GM and non-GM seed alike, it makes no sense to claim reductions in insecticide use from GM crops while ignoring this major source of insecticides.

Even without the neonicotinoid factor, Klümper and Qaim omitted the vital consideration that Bt crops do not reduce or eliminate insecticide use, but only change the way in which insecticides are used: from sprayed on, to built in. The plants themselves are insecticides. The amount of insecticide contained in these GM plants is generally far greater ( than the amount of chemical insecticide displaced.

GMO proponents often say that this does not matter because Bt toxin is a safe pesticide that has been used for decades by organic and conventional farmers. But this claim falls flat when it is considered that the engineered Bt toxin is different from the natural Bt sprayed by organic and conventional farmers. Many studies ( have found that GM Bt crops can have toxic effects on non-target organisms, including beneficial insects that help farmers and mammals that eat the crops.

Another problem with Klümper and Qaim’s analysis is that it relies ( heavily on data from the early years of GM crop adoption, before weeds developed resistance to the herbicides sprayed on GM herbicide-tolerant crops and pests developed resistance to the Bt toxins in GM Bt crops. More recent data show that GM crops have increased ( pesticide use by 7%, compared with the amount that would have been used if the same acres were planted to non-GM crops.

However, that 7% figure is likely to be an underestimate because it doesn’t include insecticidal seed treatments. When these are included, the rise in insecticide use since the introduction of GM crops will be far greater, though it is unclear how much of this rise is due to GM crops, as both GM and non-GM seeds are treated.

The neonicotinoid factor throws doubt on whether the Bt toxin trait in GM Bt crops has ever worked at all, as any pest-killing properties seen in the crops could be due to the neonicotinoid seed treatments and not the Bt trait.

WHO verdict on the toxicity of glyphosate

In 2015 the WHO’s cancer agency IARC concluded ( that glyphosate, the main chemical ingredient of the Roundup herbicide that over 80% ( of GM crops are grown with, is a “probable” carcinogen.

The IARC verdict alone exposes as false Bruers’ claim that “the herbicide glyphosate in Roundup is less harmful than many other herbicides used in conventional agriculture”. The toxicity of glyphosate and Roundup has long been underestimated. That’s largely because:

Pesticides are tested for safety by the companies that manufacture and sell them.

The safety data are kept secret under commercial confidentiality agreements between companies and regulators.

Industry tests on pesticides are carried out, and regulatory safety limits set, on the supposed “active ingredient” alone, not the complete formulations as sold and used, even though the formulations are many times ( more toxic ( than the active ingredients.

Industry and regulators largely ignore the large and growing body of scientific evidence published in peer-reviewed journals showing the toxicity of glyphosate and Roundup. Some of this research is collected here and here

The IARC conclusions should lead to a EU wide ban of glyphosate. Glyphosate is currently being re-assessed for its EU re-approval. This has led to an unseen clash between the anonymous assessors of the German agency Bfr (responsible for the Renewal Assessment Report on glyphosate) and of EFSA on the one hand, and the independent IARC scientists on the other.

In a very straightforward open letter ( 46 scientists including 9 from the IARC, argue that "the BfR decision is not credible because it is not supported by the evidence and it was not reached in an open and transparent manner" and call the European Commission to "disregard the flawed EFSA finding on glyphosate” and “for a transparent, open and credible review of the scientific literature."

They list several reasons to complain about the EFSA/BfR process:

- "the arguments promoted by the BfR to negate the human, animal    
and mechanistic evidence are fundamentally and scientifically flawed and should be rejected."

- "We strongly object to the almost non-existent weight given to studies from the literature by the BfR and the strong reliance on non-publicly available data in a limited set of assays that define the minimum data necessary for the approval of a pesticide."

See also CEO's articles on the glyphosate saga:

3. GM crops do not give higher yields

Bruers claims, “Current GM crops have a 22% higher crop yields than conventional crops and thus a lower land use.” His reference for this claim is the meta-analysis by Klümper and Qaim (

Klümper and Qaim qualify their claim of higher yields from GM crops (and confuse the scientific point) by linking it with a claim of reduce cost of production: “There are also plenty of studies showing that GM crops cause benefits in terms of higher yields and cost savings in agricultural production”.

Klümper and Qaim then give a number of grouped references, without specifying which reference supports which claim.

This unscientific linkage of two endpoints – yields and production cost – serves to muddy the waters around the question of the performance of GM crops. Higher yields from GM are difficult or impossible to prove, but there is no GM trait for high yield. The scientifically valid way to measure yield is to do side-by-side comparisons of a GM crop and its non-GM (isogenic) parent variety – but such studies are rare.

Some peer-reviewed studies of this type were collected in the Union of Concerned Scientists report, Failure to Yield. The data showed ( that GM technology has not raised the intrinsic yield of any crop. The intrinsic yields (yield potential of a crop in ideal conditions and before pests and weeds take their toll on the yield) of corn and soybeans rose during the twentieth century, but this was not as a result of GM traits, but due to improvements brought about through traditional breeding.

The study found that GM soybeans did not increase operational yields (yield that remains after pests and weeds have taken their toll on yield), either. GM maize increased operational yields only slightly in years of heavy infestation with the European corn borer pest. GM Bt maize offered little or no advantage when infestation with European corn borer was low to moderate, even when compared with conventional maize not treated with insecticides.

This interpretation of the yield performance of GM crops is shared even by the US Dept of Agriculture, which is a promoter of GM crops. The USDA says ( “Over the first 15 years of commercial use, GE seeds have not been shown to increase yield potentials... In fact, the yields of herbicide-tolerant [HT] or insect-resistant seeds may be occasionally lower than the yields of conventional varieties if the varieties used to carry the HT or Bt genes are not the highest yielding cultivars, as in the earlier years of adoption…”

The final phrase of this quote makes clear that yield depends on the background genetics of the non-GM crop into which the GM trait for herbicide tolerance or insect resistance is inserted, not the GM trait itself.

Lower production costs from GMOs?

Regarding Klümper and Qaim’s linked claim about lower production costs of GM crops, the data on relative costs of production are also problematic. They are confused by many variables such as chemical input use, pest pressure in the particular years concerned, subsidies given to farmers for growing certain crops, seed costs (which are often manipulated by seed companies to open up markets for favoured products), and irrigation.

A USDA report on the adoption of GM crops in the US gives some idea of the difficulties involved in making claims about the economic performance of GM crops ( “The profitability of GE seeds for individual farmers depends largely on the value of the yield losses mitigated and the associated pesticide and seed costs… The impacts of GE crop adoption vary by crop and technology. Most studies show that adoption of Bt cotton and Bt corn is associated with increased net returns… However, some studies of Bt corn show that profitability is strongly dependent on pest infestation levels. The impact of HT seeds (for corn, cotton, and soybeans) on net returns depends on many factors.”

By mixing the yield factor with the production cost factor and failing to specify which references support which claim, Klümper and Qaim are confusing the argument.

Klümper and Qaim’s evidence for GMO yields and production costs problematic

An examination of Klümper and Qaim’s references for their linked claims of high yields and low production costs for GMOs raises further serious problems. These papers focus heavily on Bt crops grown on a small scale, whereas over 80% of crops grown worldwide are herbicide-tolerant crops, so Klümper and Qaim’s review does not represent the GMO reality.

Also, crucially, the papers referenced by Klümper and Qaim focus on the early years of GM crop adoption, before herbicide-resistant weeds and Bt toxin-resistant pests undermined the effectiveness of the GM traits.

For example, Pray and colleagues (2002) ( focus on the early years of Bt cotton in China – 1999–2001 – before secondary pests (pests not targeted by the Bt toxins in the crop) ( moved in ( on Bt cotton. Even so, Pray’s claimed benefits for Bt cotton are unspectacular: yields for Bt cotton were between 5 and 10% higher than non-Bt. However, these were not side-by-side comparisons, where the GM crop is compared with the non-GM parent variety and grown in the same conditions. Thus yield gains, as pointed out by Prof Glenn Stone, may be due to non-GM trait-related factors ( such as “early adopter” syndrome (the best farmers tend to be the first to adopt new seeds) or the exceptional care that farmers devote to novel and expensive seeds.

In Pray and colleagues’ paper, costs of Bt cotton production were variable – less than non-Bt cotton in 1999 and 2001 but slightly higher in 2000. In a region where bollworm (the pest that Bt toxin targets) was not a problem, the authors state, “the economic benefits from Bt are not great – especially at the higher prices of Bt seed in this region”.

It is important to follow a new technology such as GM Bt crops for several years before claiming it as a success. A later study, published in 2012, documented ( emerging bollworm resistance to Bt cotton. And at the time of writing this article, Indian farmers have taken to the streets in protest ( at the widespread failure of Bt cotton in the Punjab region. Between half and two-thirds of the crop has fallen victim to whitefly attack, an example of a secondary pest problem.

Another reference given by Klümper and Qaim to back their claims of yield gains and reduced production costs for GM crops is a paper by Huang and colleagues (2008) (, on Bt rice in China in the years 2002–4. Again these are the early years of this crop, which has not been commercialized and so is not relevant to a discussion of the performance of commercialized GM crops. And the authors’ conclusions are hardly an endorsement for GM crops. They conclude, “There is at most only a small (if any) increase in yields” from Bt rice over non-GM rice, and add, “The absence of yield effects should not be surprising. A report by the Food and Agricultural Organization (FAO 2004) reported that yields usually do not rise after the adoption of Bt crops.” The authors also question “whether the nation needs any more rice or not”, as rice consumption has fallen in China.

Taken together, these studies do not support Klümper and Qaim’s claims of yield gains and reduced production costs for GM crops. Those claims appear to rely on readers of Klümper and Qaim’s paper failing to check the references for themselves.

Outdated data from Argentina used

Another reference given by Klümper and Qaim to back their claims of yield gains and reduced production costs for GM crops is Qaim and Traxler (2005). These authors reported ( a slight decrease in yield of GM Roundup Ready soybeans in comparison with non-GM soybeans. Cost savings were greater with GM soybeans. However, this was before herbicide-resistant weeds became a major problem in Argentina.

A later (2008) study noted ( that the spread of glyphosate-resistant weeds in soybean fields in Argentina and Brazil is “of major concern” and called glyphosate-resistant Johnsongrass “a major threat to glyphosate-resistant soybean productivity in northern fields of Argentina”. Farmers will try to manage glyphosate-resistant weeds by applying more and different herbicides, but this will raise the cost of production. This issue is not considered by Klümper and Qaim.

Failed GMO project in Africa used to hype GMOs

The most extraordinary reference given by Klümper and Qaim in support of favourable GMO yield and production costs is Morse and colleagues (2004) ( This paper focuses on Bt cotton in Makhathini, South Africa, between 1998 and 2001 – the first years of this project. Based on these early years, Morse states, “Bt cotton adopters achieved consistently higher yields and revenue per hectare than nonadopters over the three seasons”.

But had the authors followed the project for longer, they would have been forced to admit to very different conclusions. That’s because after its peak in 2001, the project rapidly went into steep decline and is now widely seen as a GMO crop failure.

The Makhathini project failed due to adverse weather conditions and farmer indebtedness. A 2003 report calculated ( that crop failures left the farmers who had bought expensive Bt cotton seeds with debts of $1.2 million. Pest attacks on the crop had forced farmers into buying costly insecticide sprays. A 2006 study concluded ( that the Makhathini project did not generate sufficient income to generate a “tangible and sustainable socioeconomic improvement”.

A 2012 review reported ( that by the 2010–2011 growing season, the number of farmers growing GM Bt cotton had shrunk by 90% from the number during the period of Bt cotton’s claimed success (1998–2000). Yields continued to vary widely according to rainfall levels, hovering within 10% of what they were before Bt cotton was introduced. Overall pest control costs remained significantly higher with Bt cotton (65% of total input costs) than with non-Bt cotton (42% of total input costs).

The review concluded ( that the main value of Makhathini project appears to have been as a public relations exercise for GMO proponents, providing “crucial ammunition to help convince other African nations to adopt GM crops”. The author added that there was a “disconnect” between how the project was represented and “the realities faced by its cotton growers”.

Given how the Makhathini project panned out, it is astonishing that Klümper and Qaim included these data in their review.

Increased profits claim based on outdated data

Klümper and Qaim’s meta-analysis is also Bruers’s source for the claim that farmers have increased their profits by 68% by growing GM crops. The sources for this claim are the early and outdated data cited above. But the reduced weed and insect pest control inputs that previously enabled savings in production costs can no longer be assumed to apply. Therefore the claim of 68% increased profits is not reliable.

Klümper and Qaim should explain why they failed to obtain up-to-date data that take into consideration the serious problems that have emerged with GMOs over several years of planting and which are reported to be impacting yield and performance.

Realistic picture of Bt cotton yields in India

Since the introduction of GM Bt cotton into India, there has been a fierce debate about its performance. Some claim it has delivered higher yields and improved farmer income, while others claim it has suffered widespread failure and led to farmer suicides. The main difficulty in resolving the argument is that good comparative data on Bt and non-Bt cotton performance do not exist. Typically such data would be generated from a study in which two groups of farmers matched for ability and farm conditions would be assigned to grow Bt cotton or non-Bt cotton.

Some of the most nuanced analyses of the performance of Bt cotton are by the US academic Glenn Davis Stone, who mistrusts “narratives” regarding Bt cotton from both sides of the debate. According to Stone, within five years of the introduction of Bt cotton in India, national cotton yields rose by 84%. However, almost all of that rise occurred in 2003/4, when only 1.2% of the cotton was Bt, and 2004/5, when only 5.6% of the cotton was Bt. In short, Stone concluded (, “Bt couldn’t have been responsible for the rise.”

What is more, wrote ( Stone in 2012, “In the last four years, as Bt has risen from 67% to 92% of India’s cotton, yields have dropped steadily.” According to India’s Cotton Advisory Board, yield declined ( ) to a five-year low in 2012–13.

Stone summed up ( the situation as follows: “Bt didn’t explain the big rise in yields, and since Bt has taken over, yields have been steadily worsening.”

These facts are illustrated in the graphic below.

So what explained the temporary rise in yields in the early 2000s, if it wasn’t Bt cotton? Dr Keshav Kranthi, director of India’s Central Institute for Cotton Research, believes ( that the other factor responsible for the short-term yield gains was the use of insecticides against sap-sucking pests such as the leaf hopper.

Dr Kranthi wrote (, “Since 2002, every Bt cotton seed has been treated with the highly effective insecticide, imidacloprid.” This insecticide also could also have accounted for the recent decline in cotton yield, since “Recently, leaf hoppers were found to have developed resistance to imidacloprid and… yields are likely to decline.”

Research from the University of Hannover, Germany, in cooperation with the Food and Agriculture Organization of the United Nations, found ( that Bt cotton performed better under irrigated conditions but that non-Bt local varieties were better suited to rainfed conditions. Most cotton production in India is rainfed ( Moreover, the yield advantage of Bt cotton under irrigation was offset ( by higher production costs and lower product prices.

Realistic study about GMO yields in the USA

A more realistic picture of yields for the widely grown GM crops in the USA and Canada emerges from a study ( published in 2013 by Heinemann and colleagues. The study looked at 50 years’ worth of data from North America and Europe, before and after GM crops were introduced in the US. It focused on maize, rapeseed, soybeans, wheat, and cotton. All these crops except for wheat have been subject to GM in the US and Canada. The researchers looked at comparative yields between North America and Europe, for those crops that have been subject to GM in North America. They found that since GMOs were introduced in the US and Canada in the mid-1990s, yields for Europe’s largely non-GM production have been marginally higher than yields for North America’s largely GM production. And Europe has achieved these higher yields with less pesticide use than the US.

The data show that contrary to claims by GMO proponents, Europe is not being left behind due to turning its back on GMOs, but that the opposite is true: North America’s dependence on GMO crops may be holding back progress on yields and chemical use.

4. GMOs encourage superweeds

Bruers says, “There is no good evidence of GMO cultivation resulting more quickly in superweeds than in conventional farming. Even before the advent of glyphosate-tolerant GM crops, weeds emerged that are resistant to glyphosate.”

This is disingenuous. Herbicide-resistant weeds were known before GM crops were introduced – but the odd resistant weed inhabiting a ditch or bog isn’t the same as vast populations of herbicide-resistant weeds spreading over GMO crop fields and crowding out the maize or soy that’s supposed to be thriving there.

The former doesn’t matter to farmers, whereas the latter phenomenon is impacting ( US agriculture to a “severe” degree. It’s estimated that 60 million acres of US farmland are now infested ( with resistant weeds. A study by David Mortensen, a plant ecologist at Pennsylvania State University, predicts ( that total herbicide use in the US will rise from around 1.5 kilograms per hectare in 2013 to more than 3.5 kilograms per hectare in 2025 as a direct result of GM crop use encouraging resistant weeds.

Bruers frames herbicide-resistant superweeds as a problem of modern farming and as not related to GMOs. However, GMO crops are designed to survive high doses of herbicide that would kill a non-GMO crop. This higher use of herbicides with GMO crops causes intense selection pressure. The result is large populations of resistant weeds in and around crop fields, which leads to farmers having to spray more, and different, herbicides to control weeds. The result is what plant ecologist David Mortensen calls “an accelerating transgene-facilitated herbicide treadmill, which has significant agronomic and environmental-quality implications”. In other words, this is a GMO-related problem.

And while we’ve had chemically-based agriculture since the 1950s, glyphosate-resistant superweeds have only been a problem since glyphosate-tolerant GM crops were grown on a large scale. This is confirmed by Monsanto’s own statement from 1997, when GM crops had only been introduced for one year. Monsanto scientists said ( that even though glyphosate had been used in some farming systems for many years, “no resistant weeds” had occurred. They added that the introduction of GM glyphosate-tolerant crops would not increase the “probability” of resistant weeds.

In addition, Monsanto told the EU pesticide regulatory authorities in 1999, in support of its application for the authorization of glyphosate, that it had “thoroughly” investigated all instances of resistant weeds and found only one, a ryegrass in Australia, present in only two locations, which was being “easily controlled” (see page 12 of the physical pdf in this document

Clearly, according to Monsanto’s own statements and investigations, glyphosate-resistant weeds were not a problem prior to the introduction of GM crops, and now they are.

5. Non-GMO herbicide-tolerant crops: another problem

Bruers is correct that non-GM herbicide-tolerant crops exist, so the problems caused by herbicide-tolerant crops are not entirely confined to GMOs – though practically speaking, the acreage planted to non-GM herbicide-tolerant crops is likely to be tiny compared with the GMO acreage. Just like GM herbicide-tolerant crops, non-GM herbicide-tolerant crops enable the crop to survive being sprayed with herbicide. And just like GM herbicide-tolerant crops, they pose risks ( to the environment resulting from increased herbicide sprays and risks to consumers associated with ingesting toxic herbicide residues.

For these reasons, many environmental groups oppose herbicide-tolerant crops of both GM and non-GM varieties and believe that both should be strictly regulated according to the specific risks they pose. The existence of herbicide-tolerant traits in both GM and non-GM crops also confirm environmentalists’ contention that GM is just an extension of chemical-intensive agriculture, not a sustainable alternative to it.

Where GM herbicide-tolerant crops differ from non-GM herbicide-tolerant crops is that the GM crops carry the additional risk of the disruptions to the plant genome resulting ( from the genetic engineering process. These disruptions can lead to the plant being toxic or allergenic, or to having altered nutritional value.

6. GM crops have a negative impact on biodiversity

Bruers claims that GM crops have “No higher impact on biodiversity” than conventional farming. He states, “Some reviews compare the impact on biodiversity (at the level of the crop, the farm and the countryside) between GMO farming and conventional farming and come to the conclusion that GMOs are likely to have a lower impact on biodiversity.”

The review ( that Bruers cites to back up this statement was sponsored by industry lobby group CropLife International and was authored by Janet E. Carpenter, a consultant to the GMO industry.

This conflict of interest would be of secondary importance if the information contained in the review were reliable. But the paper was published in 2011, before crucial experiments were carried out that show claims made in it to be invalid.

Carpenter (Box 2) criticizes experimental studies finding toxic effects of toxins derived from GM Bt crops on beneficial and non-target invertebrates like ladybirds and lacewings. Carpenter favours rebuttal studies that claimed to show that the original findings of toxicity in ladybirds and lacewings were false positives due to methodological flaws and bad study design.

However, subsequent experimental studies by the authors of the criticized studies, Hilbeck and colleagues, revealed ( that it is the rebuttal studies that were fatally flawed. Hilbeck and colleagues demonstrated that inadequate testing protocols were the underlying reasons for failing to find the same results in the rebuttal studies for both non-target organisms – lacewings and ladybirds.

For example, Hilbeck and colleagues showed ( that the lacewings in the rebuttal study could not have ingested the tested GM Bt toxins in the form provided by the researchers, coated onto moth eggs, as their mouthparts are formed in such a way as to make ingestion impossible. This is equivalent to testing an orally administered drug for side-effects by applying it to the skin, ensuring that none of the human subjects actually swallows the drug.

This scientific debate was high-profile and took place in the peer-reviewed literature. It is summarised, with references, in GMO Myths and Truths (

Hilbeck and colleagues’ recent studies confirming the toxic effects of Bt crops and pollen have not been scientifically refuted. Mostly, they are simply ignored by GMO proponents.

Bruers’s use of outdated and discredited experimental evidence to claim safety of GM crops is scientifically indefensible.

Non-target invertebrates on GM Bt crops

Bruers also claims, “A meta-analysis in the top journal Science found that on fields with insect-resistant GM crops (Bt crops), more harmless invertebrates (eg. insects and spiders) are found than on the fields where insecticide is sprayed.”

Bruers’s cited source is Marvier and colleagues (2007), “A meta-analysis of effects of Bt cotton and maize on nontarget invertebrates” ( Bruers chooses to look at the meta-analysis’s comparison of two unsustainable farming systems: GM Bt maize and non-GM maize where insecticides were sprayed. The review did indeed find, as Bruers notes, that when non-GM fields were sprayed with insecticides, there was a generally higher invertebrate abundance in the GM Bt maize fields.

But what Bruers omits to mention is that the meta-analysis also included a comparison that is much more interesting to proponents of sustainable agriculture: between GM Bt maize fields and non-GM maize unsprayed with insecticides. In this case, the invertebrate abundance was higher in the unsprayed non-GM maize.

This shows that opposite conclusions on the effects of GM Bt maize and biodiversity can be reached from the same evidence base, depending on which comparator is used. While GM crops may look superficially good for biodiversity when the comparator is insecticide-sprayed maize, they appear bad for biodiversity when the comparator is an unsprayed field.

One lesson that can be drawn from this study is that deciding which questions to address in scientific research should not left to scientists alone, and certainly not to biotech and agrochemical multinationals. This role belongs to society as a whole, based on its environmental protection and food production goals.

Those who argue that avoiding insecticide use on maize crops would be a farming disaster are ignoring history. Prior to the advent of GM Bt maize, according to Dr Doug Gurian-Sherman, a former biotech specialist at the US EPA and then a senior scientist at the Union of Concerned Scientists, very little maize was sprayed ( with insecticide, with only 5-10% of all maize being treated for corn borers.

Unsupported claim about GM Bt crops’ specificity to pests

Bruers claims, “GM Bt crops produce their own insecticide, so mainly the harmful insects that eat the crop are affected. When Bt insecticide is sprayed onto crops [by organic and conventional farmers], many more insect species are affected, including insects which are not harmful.”

Bruers provides no evidence to back his claims that GM Bt crops are less harmful to non-target insects than the natural Bt soil bacterium which is sprayed as a biological insecticide by organic and conventional farmers. However, many peer-reviewed studies show ( toxic effects of Bt crops and pollen on beneficial and non-target organisms, including on mammals in feeding studies with Bt crops.

Claims that natural Bt sprays are more harmful to non-target insects than GM Bt crops are questionable. Natural Bt is not a toxin but a protoxin or toxin precursor. It is only converted into a toxin when ingested by the insect that eats it. It is sprayed only when needed and in a targeted manner, to avoid pest resistance building up. Sprayed Bt breaks down rapidly in daylight. The Bt toxins in GM Bt crops, in contrast, are pre-activated toxins present in every cell of the GM Bt plants. They are ‘turned on’ all the time and thus pests are exposed 24/7. This is a recipe for the rapid evolution of pest resistance, which has occurred ( with GM Bt crops, exactly as predicted by scientists and environmentalists.

The engineered Bt toxin protein is different ( in structure and mode of action from the natural Bt used in sprays, meaning it can have different biological and toxicological properties and can lose ( its specificity to certain insect pests. Moreover, the mode of action of Bt toxin is not fully understood (

Thus Bruers’s claims of the safety and specificity of GM Bt crops are not scientifically justified.

GM herbicide-tolerant crops and biodiversity

Shifting the focus from GM Bt crops to GM herbicide-tolerant crops, which represent over 80% of all GM crops grown worldwide, Bruers’s claim that “GMOs are likely to have a lower impact on biodiversity” is once again refuted by the evidence.

The UK government-funded Farm Scale Evaluations (FSEs) looked ( at the effects on farmland wildlife of the cultivation of four GM herbicide-tolerant crops, compared with non-GM crops grown under intensive chemically-based management.

The results for sugar beet and oilseed rape showed that GM herbicide-tolerant crop management reduced weeds and weed seeds and therefore would damage farmland wildlife.

For maize the results showed GM crop management to be better for wildlife than conventional chemically intensive management. However, the conventional weed control used the toxic herbicide atrazine, which was banned in Europe before the FSE results were published.

The outcome of the FSEs was that all but one of the GM crops tested was worse for biodiversity than non-GM crops grown under intensive chemically-based management. No GM crops were subsequently commercially planted in the UK.

7. Does GM enable environmentally friendly no-till farming to be practiced?

Bruers claims that GMO farming is better for biodiversity than conventional chemical farming because it enables a “lower level of tillage (ploughing). Herbicide-tolerant crops make it possible to avoid unwanted plants without the need to plough the soil.”

However, GM crops are not necessary for no-till and low-till agriculture. No-till and low-till are practiced in both non-GM conventional and organic farming. Cover crops are a common alternative to tillage in such systems.

In fact, the majority of no-till adoption had already taken place before 1996, the year GM crops first came onto the market, according to US Dept of Agriculture data (

The USDA report says ( that adoption of no-till and low-till for soybeans grew from 25% of the soybean acreage in 1990 to 48% in 1995, the 5-year period previous to the introduction of GM herbicide-tolerant soybeans. Growth of no-till and low-till increased further in 1996, the year herbicide-tolerant soybeans were introduced, but then stagnated to 50–60% in the following years.

Biotechnology expert Dr Doug Gurian-Sherman, then of the Union of Concerned Scientists, commented ( on the findings: “Roundup Ready crops have made no-till easier, but so have no-till seed drills, and Farm Bill incentives that went into effect in 1986. If you actually look at the additional adoption of no-till after 1996, it is only a few per cent in corn, almost nothing in cotton, and a little more in soy (maybe 5 to 10% of acres). So contrary to the widespread myth, the data do not support a major role of GM crops in the increase in no-till over the past few decades.”

Environmental impacts of no-till with herbicide-tolerant GMOs

Bruers says: “The ploughing of the soil (a common practice in conventional and organic farming) is not good for the environment because it leads to less storage of CO2 in the soil (less buffer against global warming), increased use of fuels for machinery, soil erosion, more leaching of nutrients and chemicals (i.e. more eutrophication and toxic substances in rivers) and more disturbance of the soil.”

General claims of environmental benefits for GM herbicide-tolerant crops with no-till cultivation are misleading. One study compared ( the environmental impacts of growing GM Roundup Ready and non-GM soy, using an indicator called Environmental Impact Quotient (EIQ). EIQ assesses the negative environmental impacts of the use of pesticides and herbicides on farm workers, consumers and ecology (fish, birds, bees and other beneficial insects).

The study found ( that in Argentina, the negative environmental impact of GM soy was higher than that of non-GM soy, in both no-till and tillage systems, because of the herbicides used. These are broad-spectrum in nature – that is, they kill all plants except GM plants engineered to tolerate them. Also, the adoption of no-till raised the EIQ, whether the soy was GM Roundup Ready or non-GM. The main reason for the increase in herbicides used in no-till systems was the spread of glyphosate-resistant superweeds.

No-till doesn’t store more carbon

Contrary to Bruers’s claim, no-till farming does not store (sequester) more carbon in the soil.

Mortensen and colleagues found (, “Greater soil carbon and nitrogen were observed in integrated systems that used tillage, cover crops, and manure than in a conventionally managed no-till system, regardless of whether cover crops were used in the no-till system.”

A comprehensive review of the scientific literature found ( that no-till fields stored no more carbon than ploughed fields when carbon storage at soil depths greater than 30 cm was taken into account. Studies claiming to find carbon storage benefits from no-till only measure carbon storage down to a depth of about 30 cm and so do not give an accurate picture.

On the other hand, organic and agroecological methods probably do increase ( soil carbon storage.

Finally, it is questionable how much of the area planted to GM herbicide-tolerant crops is still managed under no-till or low-till systems. The spread of herbicide-resistant superweeds has undermined ( the GM no-till or low-till model of farming, forcing farmers back to ploughing and pulling weeds by hand. It is not valid to assume that farmers who plant GM herbicide-tolerant crops are not ploughing, without actual evidence.

8. Trustworthy studies and animal experiments

Bruers says, “It is distressing to see that many environmental organizations refer to untrustworthy studies and unethical animal experimentation to put the health of GMOs in question”.

If he wishes to argue that studies finding risk or harm from GMOs are intrinsically less reliable than studies finding safety, he will need to:

decide on his criteria for reliability
apply those criteria to both classes of study in an even-handed manner
present his comparative analysis of both these classes of study and prove his hypothesis that studies finding risk or harm from GMOs are less reliable.

This method was followed in a peer-reviewed study ( analyzing the European Food Safety Authority’s critique of the Séralini study, which found toxic effects in animals fed GM maize and tiny amounts of Roundup. The authors took EFSA’s criteria for rejecting the Séralini study and applied them even-handedly to the Séralini study and to publications by Monsanto alleging safety for the GM maize. The analysis found that all of the studies satisfied or failed to satisfy EFSA’s criteria to a comparable extent and that therefore EFSA’s rejection of the Séralini study and acceptance of the Monsanto studies at face value were not scientifically justified.

Bruers is welcome to write and publish his own similar analysis in a peer-reviewed journal. A well-researched article on this topic would be a service to the public and to science.

Is it unethical to feed experimental animals GMOs and pesticide residues?

If someone wishes to argue that it is unethical to feed experimental animals realistic doses of GMOs and pesticides (such as humans and livestock animals will be exposed to in the event of commercialization), then s/he should answer the question: How can it therefore be ethical to feed the same substances to humans and livestock animals?

This problem will exist as long as companies are allowed to place toxic and potentially toxic substances into the food and feed supplies. In vitro methods are not yet ready to replace animal experiments.

9. 'Natural' genetic engineering?

Bruers says, “Horizontal gene transfer such as genetic engineering is not unnatural, because in nature it also happens through viruses. Thus there is evidence that we humans have more than 140 genes derived from other species (such as algae, fungi and bacteria) and we probably acquired them by horizontal gene transfer.”

Viral infection leading to horizontal gene transfer (HGT) doesn’t prove that genetic engineering is safe – quite the reverse. Viral infection can be and often is a pathogenic (disease-causing) process. We do not know what damage these infection and HGT events caused in the past. All we know is that we are descended from the survivors of any damage that might have been caused by such events.

Scientists have long known that horizontal gene transfer (HGT) happens in nature – but that’s no reason to do it to our food crops at breakneck speed. HGT happens in nature across evolutionary timescales; the results have been selected to be benign or harmless. Humans and their crop plants have co-evolved over long periods. We and our crops are survivors of such HGT events. Those crops that caused damage, and the humans that were damaged, would have been ‘discarded’ during long evolutionary processes. A crop variety that made men infertile, for example, would have been selected out because the people who were eating that crop would not have thrived and bred.

Thus “natural” HGT and viral infections are no reason to assume that the rapid, numerous, and radical changes made in the laboratory to genetically engineer crop plants will be safe.

Prof Jack Heinemann and Dr Michael Hansen explain this in more detail here (

10. Mycotoxins and toxic celery

Bruers says, “There are indications that some GMOs can provide health benefits. Bt maize would have lower concentrations of carcinogenic mycotoxins in comparison with conventional maize.
GMOs are tested for health, and health tests can always be better. But conventionally bred crops are not tested so heavily. For example, toxic Lenape potato and celery entered the market, and were both products of conventional breeding.”

In stating, “There are indications that some GMOs can provide health benefits”, Bruers is referring to limited and outdated evidence that Bt maize can contain lower levels of mycotoxins because in the early days of commercialization, Bt maize often had less insect infestation and thus there were fewer holes in the maize for mycotoxins to proliferate in. Now that Bt maize has lost ( resistance to many pests, these studies should be re-done. The comparator should include maize grown under Integrated Pest Management and organic systems, since there are many ways of controlling pests and these should be fairly evaluated. Storage conditions also have a major influence ( on mycotoxin content, so these should be considered in any attempt to reduce mycotoxins in food and feed crops.