GMOs
What the scientific consensus actually says about genetically modified food — and why the public debate has so little to do with it.
The short version
- Genetically modified organisms (GMOs) have been consumed by hundreds of millions of people for nearly thirty years; the scientific consensus across every major food safety authority in the world is that currently approved GMOs are safe to eat.
- The principal objections to GMOs are not primarily about food safety — they are about corporate control of the food system, intellectual property over seed genetics, and the social and economic consequences of agricultural consolidation.
- GMO labeling laws exist in more than 60 countries; the U.S. adopted a mandatory disclosure standard in 2022, though one that allows QR codes rather than clear on-package text in many cases.
- Next-generation genetic editing tools, particularly CRISPR-Cas9, are blurring the regulatory line between 'conventional' and 'GMO' crops and will require new governance frameworks that current regulations were not designed to address.
What it is
A genetically modified organism is one whose genome has been altered through genetic engineering — the direct manipulation of DNA in ways that do not occur through conventional breeding or natural mutation. This distinguishes GMOs from plants and animals selectively bred over generations, though the conceptual boundary is less clean than it appears: selective breeding also modifies genomes, just more slowly and with less precision. Modern GMO techniques typically involve inserting one or more genes from another organism into the target genome, using tools like Agrobacterium-mediated transformation or gene gun techniques, to confer a specific trait. Since the first commercial GMO crop — the Flavr Savr tomato — was approved by the FDA in 1994, commercialized GMOs have been dominated by a small number of traits: herbicide tolerance (primarily Roundup resistance, enabling fields to be sprayed with glyphosate without killing the crop) and pest resistance (Bt crops, which produce a bacterial protein toxic to specific insects).
The scientific consensus on the safety of consuming approved GMO foods is as clear as scientific consensus gets on a contested public question. The National Academies of Sciences, Engineering, and Medicine conducted a comprehensive review in 2016, examining over 900 studies spanning 20 years of GMO crop cultivation, and concluded there was no substantiated evidence of a difference in risks to human health between approved GMO and conventionally bred crops. The WHO, the American Medical Association, the European Commission (which funded over 130 research projects on GMO safety over more than two decades), and food safety authorities in virtually every country with a major food safety regulatory system have reached similar conclusions. This consensus is not unanimous among all scientists — it rarely is on any empirically active question — but the dissenting scientific literature has been examined and found methodologically inadequate by multiple independent review bodies.
The major GMO crops in commercial production are soybean, corn, cotton, canola, alfalfa, and sugar beet — commodities that primarily enter the food system as processed ingredients (soybean oil, corn syrup, cottonseed oil) or animal feed rather than whole foods consumed directly. Approximately 90% of corn and soybeans grown in the United States are GMO varieties. This means that a large share of processed food containing corn or soy derivatives already contains GMO-derived ingredients, regardless of consumer awareness. Direct-to-consumer GMO whole foods have been more limited: non-browning Arctic apples, non-bruising Innate potatoes, and virus-resistant papaya (which saved Hawaii's papaya industry from a ringspot virus that would otherwise have destroyed it). The virus-resistant papaya is perhaps the clearest case of a GMO crop delivering direct public benefit without obvious corporate capture.
CRISPR-Cas9 and related gene-editing tools have created a new regulatory ambiguity that is currently being worked out differently in different jurisdictions. CRISPR allows precise edits to an organism's existing genome — deleting a gene, correcting a mutation, or making small modifications — without necessarily introducing DNA from another organism. These edits can in principle produce outcomes identical to what could occur through natural mutation or conventional breeding. The U.S. Department of Agriculture has ruled that many CRISPR-edited crops fall outside its GMO regulatory framework because they don't contain foreign DNA; the European Court of Justice initially ruled that CRISPR crops require the same regulatory review as traditional GMOs, though the EU has been reconsidering this approach. The technology is advancing rapidly enough that existing regulatory frameworks in every major jurisdiction are under pressure to update.
Why it matters
The public controversy over GMOs has been persistently decoupled from the scientific evidence on safety, in ways that are instructive about how scientific consensus does and doesn't translate into public belief. A 2015 Pew Research poll found that 88% of AAAS scientists considered GMO foods safe to eat, while only 37% of the general public agreed — a 51-percentage-point gap, larger than the public-scientist gap on climate change at the time. The GMO fear narrative in the U.S. and Europe was substantially amplified by a set of activist organizations — some funded in part by the organic food industry, which has a financial interest in GMO skepticism — and by scientific misconduct cases including the retracted Séralini rat study (2012), which claimed to show GMO corn caused tumors in rats and was retracted for methodological failures so severe that the journal later stated the findings were unreliable. The retraction received a fraction of the attention the original paper generated.
The legitimate concerns about GMOs are largely not about food safety. They are about corporate concentration and intellectual property in agriculture. The GMO seed market is dominated by a small number of companies — Bayer (which acquired Monsanto in 2018), Corteva, ChemChina (which acquired Syngenta), and a few others — which hold patents on the genetic traits in most major commercial GMO crops. Farmers who plant patented GMO seed typically sign licensing agreements prohibiting seed saving — the traditional agricultural practice of keeping seed from one year's crop to plant the next. These contracts represent a genuine structural shift in the agricultural economy, concentrating intellectual property over the food supply in a small number of corporations with global market power. This is an important critique; it is distinct from whether the food produced is safe to eat.
The glyphosate dimension adds a layer of legitimate complexity. The dominant herbicide-tolerant GMO crops are engineered to survive spraying with glyphosate (Roundup), which means the adoption of Roundup Ready crops is inseparable from dramatically increased glyphosate use. Glyphosate was classified as 'probably carcinogenic to humans' by the International Agency for Research on Cancer (Group 2A) in 2015 — the same category as red meat and working as a hairdresser. The EPA and European Food Safety Authority, using different methodological frameworks, have concluded glyphosate is not likely carcinogenic at exposure levels encountered by consumers. The science is genuinely contested in a way that the food safety question about GMOs per se is not, and the herbicide-tolerant crop system cannot be evaluated independently of the herbicide. Bayer has paid more than $10 billion to settle thousands of lawsuits from plaintiffs claiming glyphosate caused their non-Hodgkin's lymphoma.
Golden Rice — a GMO variety engineered to produce beta-carotene as a response to vitamin A deficiency that kills hundreds of thousands of children annually in developing countries — has been in development since the late 1990s, received regulatory approval in several countries including the Philippines (2021) and Bangladesh, and has been blocked or delayed by anti-GMO activism in precisely the countries where it was intended to help. It is perhaps the most discussed ethical case in the GMO debate: a non-commercial crop developed with public funding to address a public health crisis, impeded by opposition that has prioritized opposition to the technology category over its specific application. Greenpeace, which has opposed Golden Rice, has acknowledged it does not oppose Golden Rice because of food safety concerns but because it believes the crop would undermine the case for non-GMO agricultural alternatives. This is a transparent policy preference being litigated through a scientific language of food safety concerns.