Confused about the mixed messages on GMO foods? Here’s what the evidence says

Genetically modified foods have been met with consumer backlash since they were first introduced in the 1990s. Recently, however, calls for non-genetically engineered options have gotten even louder.

In April, Major North American fast food chain Chipotle announced it would endeavor to provide non-genetically engineered menu options (which is, albeit, not 100% possible). This past summer, celebrities including Jordana Brewster and Ginnifer Goodwin signed on to a campaign calling on U.S. food companies to reveal ingredients derived from genetically modified organisms (GMOs). And the New Democratic Party of Canada has recently called for labelling of genetically modified foods.

These campaigns are based on concerns that GMO foods might not be safe for consumption or could damage the environment. Anti-GMO proponents claim GMO foods are linked to everything from cancer to allergies. The David Suzuki Foundation’s website warns “a growing body of research connects [GMO] foods with health concerns and environmental damage.” (A media representative of the David Suzuki Foundation explained that the Foundation couldn’t provide an interview because none of the scientists at the organization are currently researching GMO foods.)

In contrast, major governmental and health organizations, including Health Canada, the European Commission and the Food and Drug Administration, have examined hundreds of studies and concluded that there is no evidence GMO foods are any less safe for consumption than conventional foods.

When the independent non-profit PEW Research Center asked scientists and members of the public about their views on 13 commonly debated topics, genetically modified foods was the issue that divided scientists and the public the most. In the 2015 poll, 88% of scientists polled across an array of disciplines responded that GMO foods are safe, while only 37% of the general public believed they were safe.

We look at what the evidence says about the GMO foods that are currently on the market.

What are GMO foods?

Genetically modified foods are foods that come from plants with DNA that has been changed in a way that does not occur naturally by conventional or modern breeding techniques. This could mean changing the way a gene in a plant behaves, or inserting one or more gene into the genome of a plant, which contains tens of thousands of genes. The inserted gene, which might be derived from viral, bacterial or plant DNA, is added because it contains a desired trait.

While food can be modified for a variety of reasons, including to make it more nutritious, the genetically modified foods we’re exposed to have generally been modified for two reasons, according to Rene Van Acker, professor and associate Dean of the Ontario Agricultural College at the University of Guelph. “The traits that we’re talking about that are GM-conferred are herbicide tolerance or insect resistance,” says Van Acker. With genetically modified corn, for example, a bacterial gene is inserted because it produces a protein that is toxic to some insects, but not to humans.

One major exception, points out Andreas Boecker, a professor in Food, Agricultural & Resource Economics at the University of Guelph, is the Hawaiian papaya, which was facing extinction before it was genetically modified to be resistant to the virus killing it.

One of the biggest misconceptions of GMO foods is that “almost all produce is genetically modified,” says Van Acker. Because genetic modification is expensive, the technology is only cost effective when applied to large-scale crops, such as wheat, soy, canola and corn. So while the tomatoes we buy aren’t genetically engineered, more than 90% of soy growing in the US is genetically modified to tolerate herbicides.

What do we know about the safety of GMO foods?

Before a genetically modified product can be sold to farmers or consumers, the company producing the GMO food must perform numerous safety tests and submit nutritional and allergenic information on the product to Health Canada. According to Brian Ellis, a professor in the Department of Botany at the University of British Columbia, it’s a process that takes years and is extremely expensive. “The approval process can cost over $100 million dollars to bring a really new genetically modified product to the market,” says Ellis. “Most of that cost is the testing.”

Safety testing is meant to screen out products that could be harmful. For example, when soybeans developed by Pioneer Hi-Bred International were found to have the same chemical that causes peanut allergies, the product was abandoned and never went forward to market. None of the GMO products thus far approved have been shown to have any adverse health outcomes.

“These foods have undergone more extensive testing than any food that has come on the market,” explains Joe Schwarcz, professor of chemistry at McGill University and director of the Office for Science and Society.

In addition to the industry tests, numerous independent studies have been conducted. In 2010, the European Commission released a summary of 130 research projects on GMO foods that had been funded by the Commission over a decade. The studies revealed “no scientific evidence associating GMOs with higher risks for the environment or for food and feed safety than conventional plants and organisms,” according to a press release from the organization. A systematic review of animal feeding trials (both industry and non-industry funded) also concluded GM plants to be safe.

As with fluoride in water or vaccines or almost any health-related technology, some animal studies have been used to suggest that GMO foods could cause harm to human health. These studies are too methodologically flawed, however, to prove anything.

Some scientists and anti-GMO activists argue that GMO foods cannot be seen as safe because epidemiological or large-scale randomized controlled studies in humans haven’t been carried out.

Schwarcz points out that even though “we’ve been eating these foods for 20 to 25 years,” it’s possible “there is some subtle health affect and we wouldn’t know it because we live in such a complex world.” He is quick to point out, however, that “we know a lot” about the safety of GMO foods. “Based on what we know about the technology involved, and based on what we know about the body, it’s extremely unlikely.”

Should we be worried about GMOs damaging the environment?

More prominent than the health concerns with GMO foods are the environment-related fears. Here the science is more contested, especially because the scientific community has not agreed on standardized methodologies when it comes to measuring environmental impacts.

One review of around 850 studies concluded that genetically engineered crops have not had more negative environmental impacts than conventional crops. But some studies have raised potential risks – such as to moths or butterflies in surrounding fields – that require further research.

An especially polarizing environmental issue is whether GMO crops increase or decrease the use of chemicals in agriculture. In explaining its decision not to use GMO ingredients, Chipotle cites a study that estimated pesticide and herbicide use increased by more than 400 million pounds over four years due to GMO crops. The study was conducted by a scientist funded by the organic food industry.

One European government-funded review of 147 studies came to the opposite conclusion, finding that GMO crops had resulted in a 37% drop in pesticide use. While many of the studies were industry funded, the researchers analyzed the studies by funding source and found industry funding did not “significantly influence the impact estimates.”

Van Acker is of the opinion that more long-term studies are necessary to see if GMO foods increase or decrease herbicide and pesticide use. He explains that while GMO crops initially result in less chemical use, as weeds develop resistance or GMO crops spread into unwanted areas, pesticide and herbicide use can increase over time. He explains, however, that once GMO crops begin to require more expensive chemicals, farmers tend to stop using them. “Farmers are not pro-GM crops or anti GM-crops,” says Van Acker. “They’re pro-whatever is good for their business.”

Sylvain Charlebois, currently a visiting professor at the University of Innsbruck in Austria, says that it’s important that governments and independent institutions continue to fund studies on the environmental and gene flow effects of GMOs. “It’s important to make sure that we assess longitudinal, environmental risk, and that’s hard to assess in a lab,” says Charlebois. Boecker agrees. While he is sympathetic to arguments that GMO science is too heavily dominated by industry, he argues that rather than restricting or labelling GMO foods, the debate should instead focus on “how much do [independent research institutions] need to invest in risk assessment and management to make risks acceptable?”

Why is there a disconnect between scientists and the public on GMO foods?

 The science thus far tells us that GMO crops don’t pose a risk to human health and could have both positive and negative environmental affects that need to be continually monitored and mitigated. So why do most consumers feel GMO foods are dangerous?

Partly, the public opinion reflects “a fundamental distrust of science and technology,” says Ellis. “It’s a thread that runs strongly through our society still.” One recent survey found that while 72% of respondents think it’s important to know science in their daily lives, a third of respondents believed scientists adjust their findings to get the answers they want. Inaccurate reporting of science relating to GMO foods in mainstream media and blogs hasn’t helped.

Stemming from this distrust is the belief that there is something intrinsically bad about human interventions in natural processes, explains Schwarz. “Nature is not exactly benign,” he says, making reference to “viruses, bacteria, natural carcinogens, alfatoxins.” Plus, he says, the movement of foreign genes into plant DNA is not so contrary to nature. “Humans are constantly exchanging genes with bacteria,” he explains.

But Charlebois says GMO producers are also to blame for the confusion. In a case study of Monsanto, Charlebois found the company allowed distrust and ill will to proliferate because the company largely ignored the public, instead engaging with farmers and agricultural industry stakeholders on GMO science. “They were selling a product without really engaging with consumers,” he says. Though he admits the distrust of the technology is partly due to a general distrust in the major corporations that use it, Charlebois argues that the “Frankenfoods” fears could have been better countered had industry scientists engaged with the public through the mainstream and social media.

Perhaps learning from the importance of public dialogue, Arctic Apples, the company behind the non-browning apple recently approved for sale in Canada, prominently explains on its website how biotechnologists modified the apple by turning off the activity of certain genes. Commonly called “gene editing,” this practice is different from transferring foreign genes into a genome, but Ellis predicts that gene editing will become a more common method of genetic modification in the future.

In the end, trust in GMO foods may have less to do with the science and more to do with how that science is explained – by the media, by scientists and by industry representatives. “The activists are very good at what they do in getting their message out,” argues Schwarz. And the scientists? “They’re not.”