Periodically, I see headlines or tweets referring to a scientific consensus on the safety of genetically modified foods (GMOs). Famously, Bill Nye reversed his initial negative assessment of GMOs, for which he had received much criticism; most recently, the consensus has been invoked again in reference to the new GMO labeling bill that recently passed into law in the United States.
I've been repeatedly frustrated by this assertion of consensus, as a scientist who studies food and food systems, I have several concerns regarding the social and ecological risks of GMO foods, concerns that are founded in scientific research and that I know I share with numerous colleagues. Further, I also do not see any scientific consensus that these risks are worth taking: that GMO foods solve problems that non-GMO foods, alternative farming practices, and political reforms cannot solve as well.
There are a number reasons that people question GMOs. Most commonly invoked is a concern regarding whether or not they are safe to eat. To my knowledge, there is indeed no evidence that the GMO foods currently in production are unsafe. What's more, several studies, including one of billions of livestock fed GM, feed have indeed shown no adverse effects. Yet, I would point out that lab-based genetic modification makes any number of possible genetic permutations possible, far beyond what can be achieved by traditional selection, hybridization, and seed saving. As such, it is a weak inference to move from the negative results of studies of existing GM crops (you can't prove safety, but can show a lack of evidence of harm), to an assumption of safety all GMOs developed in the future. What's more, despite much compelling evidence, some scholars have recently come out directly against this notion of there being a consensus about a lack of human health risks (see also here).
However, we need to broaden how we define and discuss safety with respect to GMOs. More than just a question of biomedical health, what do GM crops mean for local ecosystems? What do they mean for local farmers? And, what do they mean for local and global food security? In the numerous academic discourses on these questions, we see everything but consensus. I will explore each of these issues in more detail below, but suffice to say, each of these ongoing debates underscores the importance of labeling.
First, however, I need to dispel an argument that often accompanies assertions of the safety of GMOs--that laboratory-based genetic modification is fundamentally no different a technology than seed saving and farm-based hybridization. This is simply untrue. One important difference is that in the field, domestication and artificial selection occur in an interplay with wild biodiversity. In the history of crop and animal domestication, genetic interaction among domesticates and wild biodiversity was essential in the development of species and varieties adapted to local conditions. Today, field-based development of new varieties continues to rely on the influence of local environments. In the lab, however, genetic modification benefits from none of these external inputs, and this has ramifications for the question of whether or not GMOs are ecologically "safe". Domesticates are generally poor at reproducing without human intervention, but pollen drift is a legitimate issue (a similar issue can be raised for genetically modified salmon). We simply cannot know ahead of time what sorts of ecological consequences different GMOs may have in different ecosystems. However, what we can infer from niche theory is that the risks of novel, disruptive species emerging would be significantly lower for new varieties developed in situ as opposed to those developed in a lab.
There are numerous other possible environmental concerns, regarding the use of pesticides, the development of herb-resistent weeds, and health impacts of plant and animal exposure to Round-up and neonicotinoids. There is simply no consensus about these issues (see also here); in some cases, the issues are specific to specific GMOs (e.g., those modified to contain Bacillus thuringiensis (Bt)), further underscoring the problem with blanket proclamations regarding GM technology.
A second and hugely important way that GM differs fundamentally from traditional crop development is the context of intellectual property law within which capital-intensive, for-profit genetic modification takes place. Seed saving is a technology that is open to any farmer or gardener, by simple virtue of their ability to grow plants. By comparison, only corporations with significant resources can enter into the world of gene sequencing and lab-based genetic modification. Couple this limited ability to participate with the ability to patent new varieties, and you open the door for putting control over the world's food supply into the hands of a few corporations.
Gary Nabhan, in his excellent book Where Our Food Comes From, makes clear the issue of control over seeds in his gripping discussion of Nazi Germany's attempts to seize the collection of Russia's largest seed bank during their occupation of Stalingrad. The 3rd Reich knew very well that if you control the food, you control the people. For other extensive examinations if this issue, see Jack Kloppenburg's First the Seed, and Vandana Shiva's Stolen Harvest.
Admittedly, this is not an issue inherent to the technology itself, but the political and social context within which GMOs or any technology for that matter is being implemented cannot be ignored. The numerous unintended social and ecological harms of the 'Green Revolution' in Asia and Latin America are poignant examples of what happens when technology is applied without thinking about the social and political ramifications (see also here and here).
The question that must be asked, therefore, when determining the 'safety' of GMOs for the farmers of the world, is whether or not the changing political economy of control over seeds, especially if it trends in the direction of greater corporate control, will empower or disempower farming families and the communities that rely on them. On this question there is no consensus, and several legitimate concerns. On a personal note, these concerns are why I want GMOs to be labeled, so that I can choose not to participate in the further corporatization of food systems.
Next is the question of whether or not the production of GMO foods creates risks for food security. One way to answer this question is from the perspective of diversity: an important indicator in the stability and resilience of food systems. According to the Food and Agriculture Organization of the UN, "since the 1900s, some 75 percent of plant genetic diversity has been lost as farmers worldwide have left their multiple local varieties and landraces for genetically uniform, high-yielding varieties." On this point, it is essential to admit that GMOs are not solely responsible, but we must nonetheless recognize that GM technology embodies the underlying industrial philosophy of standardizing and simplifying agricultural systems. Highly standardized and specialized systems are generally less resilient and more vulnerable to disruption and climate change (see also here and here). It is fair to say that much of the intent behind using GM technology in foods is to increase simplicity and standardization (e.g., built-in pesticides and herbicide resistance). Likewise, a few labs creating varieties for the entire world to grow cannot compete with a world full of producers developing local varieties in terms of promoting crop diversity.
But what about the benefits?
If we accept that there are risks to GMOs, even if they are difficult to quantify (you don't know what you don't know), we can evaluate whether the purported benefits of GMOs justify those risks. As I say above, there is not consensus on this, though my reading of the academic literature is that the answer is generally no--the various promises of GMOs are all falling through.
Take the question of agricultural productivity. An argument is often made that only GMOs are capable of feeding the world's growing population. Yet, if we put aside for a moment the fact that food insecurity and hunger are rarely a food production problem, and also put aside the fact that most GM crops are used to feed livestock, not hungry people, comprehensive reviews of research show that agroecological approaches to food production actually out-perform industrial, GM-based ones, in terms of overall productivity and also conservation of land and wild biodiversity.
Another argument is made regarding climate change, and the need to use GM technologies to make crop varieties that will withstand future conditions. As I already noted above, research shows that agriculture in North America, where GM and industrial practices are widespread, are more vulnerable to climate change than more diversified systems in the developing world. What's more, recent research shows that field-based development is outperforming GM approaches to creating new, drought-tolerant varieties.
Finally, some people appeal to GMOs as a way to develop more nutritious varieties of foods. However, research shows both that vegetables have declined in the last several decades in terms of nutritional value and that organically produced foods often have greater nutritional value than those produced using conventional methods (and here). This is in part because the stress caused by pests on plants, which is intentionally reduced in GM-based production systems, drives the production of antioxidants and other sources of plant-based nutrition.
Our Food Is Not Broken
Hidden within the push for the widespread acceptance of GMOs is this notion that our food is somehow broken, and need of improvements that only laboratories and scientists can provide. If I have one goal with this essay in addition to dispelling the idea that there is scientific consensus on GMOs, it is to emphasize that our food is not broken. That doesn't mean that our foods need to remain fixed in time, and indeed the history of crop diversity, at least until the 1900s, has been a remarkable tale of dynamic and expansive diversity.
Likewise, I am not saying here that GM technology has no place in our food systems. I do, however, think it is imperative that we remain open to the need to deliberate as communities and societies the social acceptability of any and all technologies. That GMOs (currently) pose no known health threats does not mean that there are not other, equally legitimate moral or economic or ecological criteria upon which people ought to have the right to choose to engage or not with GM technology. The only way to ensure this, however, is with transparency--with labels.
The legitimacy of such debates, however, is undercut by proclamations of "consensus" that result in those people with legitimate concerns being labeled "anti-science".
PS- Please PM me on twitter @conservechange if you want but do not have access to some of the journal articles referenced here.