A massive National Academy of Science review of hundreds of studies on genetically engineered (GE) food crops, comparing the US, where the crops have been used heavily for 20 years, and Europe, where use is rare, finds no reliable evidence that these crops pose any harm to human or environmental health. The expert panel has posted its report online, along with the evidence they rely on, in the hope that their massive meta-analysis might inform public thinking about the issue. The sad thing is, given the nature of human risk perception, minds already made up on the issue are unlikely to change.

We’ll get to the depressing explanation of why that’s the case in a minute. First, let’s look at the findings. If your mind is open and you just want to learn about the issue, they seem pretty persuasive.

Based on a review of more than 900 studies, testimony from more than 80 expert speakers in three public meetings and 15 public webinars, and roughly 700 comments from the public, the 20 experts, all academics with no direct ties to the agricultural biotechnology industry, wrote;

The committee examined epidemiological data sets from the United States and Canada, where GE food has been consumed since the late 1990s, and similar datasets in the United Kingdom and western Europe, where GE food is not widely consumed. No pattern of differences was found among countries in specific health problems (including a list of diseases that opponents say are caused by genetically modified organisms - GMOs - like cancer, obesity, gastrointestinal tract illnesses, kidney disease, and disorders such as autism spectrum and allergies) after the introduction of GE foods in the 1990s.

On environmental impacts, the experts found that planting crops engineered to include Bt genes (bacillus thuringiensis, a natural insecticide approved for use on organic farms)

tended to result in higher insect biodiversity than planting similar varieties without the Bt trait and using (harsher, more toxic) synthetic insecticides.

They found that while overall herbicide use decreased at first when GE crops first went into use, “those decreases have not been maintained”, cautioning however that the use of some herbicides is down, while use of others is up, and the overall number doesn’t tell us much.

Total kilograms of herbicide applied per hectare is an uninformative metric for assessing (risk, since) the environmental and health hazards of different herbicides vary…

Here’s their overview:

While recognizing the inherent difficulty of detecting subtle or long-term effects in health or the environment, the study committee found no substantiated evidence of a difference in risks to human health between currently commercialized genetically engineered (GE) crops and conventionally bred crops, nor did it find conclusive cause-and-effect evidence of environmental problems from the GE crops, cautioning that ”…the complex nature of assessing long-term environmental changes often made it difficult to reach definitive conclusions.

            Pretty persuasive…if your mind is open and you just want to see what the bulk of the evidence says. But if you’ve already decided that GE technology is dangerous, you will find ways to deny this strong scientific statement. You might say, as some anti-GMO groups are saying, that the committee members were too close to industry, the standard ‘don’t trust the experts’ ad hominem mudslinging that advocates use when they can’t attack the facts themselves. A Friends of the Earth spokesperson said;

“I’m concerned that their findings and recommendations are deceptive and even biased toward industry interests.”

 (The study was funded by independent foundations and the USA government, and externally peer reviewed.)

You might cherry pick through all the careful scientific qualifiers the experts used, as scientific experts do… to be to super cautious about their language…and find the phrases that still sound scary. That’s what Consumers Union anti-GMO advocate Michael Hanson did in a comment to the Washington Post, pointing out that the committee acknowledged that allergens genetically engineered into new hybrids might be hard to detect before the food gets to market. (Which ignores the NAS panel finding that in the 20 years that hundreds of millions of people have been eating food with GM ingredients, there is no evidence that’s happened.)

You might criticize the report because it “is inconsistent about regulating new genetic modification techniques like genome editing and synthetic biology,” as the anti-GE ETC Group complained…even though the NAS report specifically said that, given the increasing variety of ways we can modify the genes in the crops (and animals) we grow, that risk assessment should focus on the food we actually eat, not how it’s made.

All technologies for improving plant genetics—whether GE or conventional—can change foods in ways that could raise safety issues. Therefore, it is the product that should be regulated, the report finds, not the process (i.e., genetic-engineering or conventional-breeding techniques).

            Or you could go all in and just say that 20 years of evidence isn’t enough, as GE opponent Charles Benbrook did, saying that there aren’t enough human health studies, or as food expert Marion Nestle did, telling the Washington Post “the report reveals how little is known about the effects of GE foods.”

- - -

            But now we get to the second point, the depressing lesson this whole GMO issue teaches, a lesson with implications about how society struggles to deal intelligently with a wide range of matters. When it comes to how we see risk issues like this, the facts don’t matter. Or to be more specific, the facts matter less. What matters most as we make up our minds is how we feel about the issue. We see the facts through the filters of our emotions and instincts. We see untrustworthy big companies profiting from doing unnatural things to our food and agricultural systems, imposing a potential risk on us without telling us (the labeling issue), and for many of us, those psychological characteristics set off instinctive alarms go off. The fact that agricultural biotech is done by big companies does not inherently make food riskier. The fact that some forms of genetic engineering create hybrids that could not occur naturally does not inherently make those hybrids riskier. The fact that labels don’t tell us absolutely everything about every ingredient in our food does not inherently make the food riskier. But those psychological factors all make the food feel riskier.

            That is a large part of what the fight over GE crops and agricultural biotechnology is all about. It’s not a matter of what the evidence says, alone. It’s how we feel about that evidence, which subconsciously alters the conscious positions we take. This is why various sides of various issues can see the same facts in such different ways.  Despite remaining uncertainties (and there are ALWAYS remaining uncertainties) the body of evidence on GMOs is strong and clear. But fears of unnatural risks imposed on us by untrustworthy big corporations are just as strong, at least among the small but passionate community of those opposed to genetic engineering generally. This is a fight about feelings and values. It’s one of those unresolvable conflicts we face in modern society when a complicated issue comes along and we have to rely on critical thinking and careful reasoning to figure out what’s best, only we’re stuck with a risk perception system that evolved to handle risks – lions and tigers and bears, oh MY! – that were much simpler.

The danger here is that our emotion-based risk perceptions might lead us to support policies that feel right but don’t do us the most good. Resistance to agricultural biotechnology, which offers huge potential benefits from which millions are not yet benefiting (as the NAS panel itself noted), is just one scary example. The fight over climate change is slowing down action to prevent it. The persistent fear of fluoride, or childhood vaccines, exposes communities to public health risks. The values-based battle over reasonable gun safety regulations that a majority of Americans support puts us all, legal gun owners included, in greater danger.

            So thank you NAS panel for an honorable job, confirming what was already well-established; first, that GE crops pose no known risk to human or environmental health, and second, that dangers can arise from our subjective, emotion and instinct-based risk perception system, a system that’s supposed to protect us but that sometimes leaves us more worried that the evidence warrants. We need to be wary about real threats, but also, as George Carlin once observed, because “There are nights when the wolves are silent and only the moon howls."

About the Author

David Ropeik

David Ropeik is the author of How Risky Is It, Really?, an instructor at Harvard University Extension School, and a risk-communication consultant.

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