Editor’s note: In a new report, the National Academies of Science, Engineering and Medicine have provided a broad review of available information on genetically engineered (GE) crops and their impacts on the environment and human health.
The study, produced by a committee of 20 experts from diverse fields, found “no conclusive evidence of cause-and-effect relationships between GE crops and environmental problems,” such as reduced biodiversity in areas where GE crops are planted. Similarly, it found “no substantiated evidence” that foods from GE crops are less safe than foods from non-GE crops.
However, the report also concluded that although planting crops engineered to resist pests and/or herbicides generally has paid off economically for farmers, damaging levels of resistance have evolved in some targeted pests and weeds. And it found that regulations governing GE crops in some countries, including the United States, should be updated to reflect advances in genetic engineering.
Here we offer perspectives from three members of the study committee. Their comments underline a major theme of the report: discussions about GE crops need to move past broad pro/con statements and address the complexities of this fast-evolving field.
Director, Institute of the Environment and Sustainability, University of California, Los Angeles
There is no denying the impassioned public controversy surrounding GE crops and food. Somehow, the scientific community has been largely caught off guard by this debate – perhaps by not fully appreciating how deeply people relate to their food and how it is produced.
Given the swirl of public misgivings, I am proud of what is a profoundly sensible report, and a process that really listened to the public. Our committee held three public meetings and heard from 80 invited speakers. We received over 700 public comments and read every one of them. We trudged our way through hundreds of published scientific articles.
I know many people want a definitive unqualified “thumbs up” or thumbs down” from our committee. They are not going to find it in this report. Because GE crops are developed in so many different ways, with so many different traits, and in so many different plant species or varieties, we cannot give a one-size-fits-all verdict. Hoping for a simple yes or no in this matter is akin to expecting a committee of experts to conclude “men are good” or “men are bad.” However, setting aside absolutes, we can say some things that should be useful to the public dialogue.
The adoption of GE crops has yielded generally positive economic benefits (but not always), and in some cases clear environmental benefits. For instance, the widespread planting of crops with insect-resistant traits has reduced the spraying of insecticides. While there is some evidence of yield increases due to GE crops when simultaneous field-to-field comparisons are made, it is hard to attribute global improvements in crop production to GE technology at a time when many aspects of the farming system are changing, and when conventional breeding is also making improvements.
Many people worry that GE foods may have adverse effects on human health. I personally found this literature challenging (it is not my field) and fascinating. We went back to original studies in which animals were fed GE foods, and also looked at epidemiological data for humans. We found no solid evidence that foods from GE crops were less safe than foods from non-GE crops.
Promises have been made about GE crops addressing world hunger. GE crops alone cannot do this, and there are major challenges in fitting them into local environments, averting the evolution of resistance in the case of anti-pest modifications, and making GE seeds available and helpful to smallholders (small farmers).
Emerging technologies and new traits may hold great future promise. For example, research is underway around the world to develop crops that use nutrients more efficiently and increase their drought tolerance and disease resistance. It is too early, however, to predict what results will come from this work.
Continued regulatory vigilance is warranted. Any new crop variety with novel traits – whether genetically engineered or conventionally bred – should be subjected to safety testing, but in a tiered fashion so that testing is directed where it is most needed. Our report calls for increased transparency and public participation, and as a researcher in the field I personally hope that it catalyzes the establishment of open data bases tracking GE adoption and impacts.
Adoption of insect-resistant (Bt) and herbicide-tolerant (Ht) crops in the United States U.S. Department of Agriculture
Associate Professor of Rural Sociology and Science, Technology, and Society, Pennsylvania State University
There are several valuable insights in this report. It avoids making simplistic and authoritative pronouncements about GE crop technologies. People should avoid viewing GE crops as a single thing that is either beneficial or harmful.
Herbicide-resistant, insect-resistant and virus-resistant crops, for example, are three very different technologies and have had different social, economic and environmental impacts. New and emerging technologies and applications, such as CRISPR-Cas9, add further nuance and complexity.
As a sociologist, I think the report’s most important finding is that the social and economic effects of GE crops will vary by the type of GE crop developed, the economic and environmental contexts of the farms that adopt them, and the social and economic contexts. For example, studies show that benefits to small-scale farmer in developing countries from planting Bt (insect-resistant) cotton have varied widely, depending on factors including seed prices, availability of credit and farmers' access to markets.
It is very important to avoid thinking about GE crop controversies as two groups of people pitted against each other – one group in favor, the other against – or that GE crops are either good or bad. Many perspectives are relevant, and GE crop technologies are complex and varied.
These technologies and applications are changing very quickly, and I found myself hustling to comprehend those changes as a participant in this study. But I learned something more profound in the process. New knowledge emerges when people from different disciplines and subdisciplines exchange their research and expertise in an engaging and constructive way. The public presentations and public comments that the National Academy organized in connection with this report stimulated our research and discussions. As a result, the report represents something more than the sum of its parts.
I sincerely hope that this study expands the conversation beyond technological determinism and the tired, old, two-sides-to-every-argument approach to discussing GE crops. It is common for GE crops to be portrayed either as solutions to social and economic problems or as causes of them. GE crops are also commonly presented as though there were only two sides to this debate: either you are for it or against it.
New technologies bring both promises and perils, and aspects that are promising to some people are perilous to others. The report makes it very clear that assessing the experiences of and prospects for GE crops is about more than merely evaluating technical risks. Legal, economic, social, cultural and individual factors are also relevant.
Michael A. Gallo
Emeritus Professor of Environmental and Occupational Medicine, Rutgers University Newark
As a toxicologist, my major concerns with respect to GE crops are impacts on human and animal health. We reviewed approximately 400 to 500 studies, starting from before genetically modified organisms were commercialized. Our general conclusion was that the GE crops tested were no more harmful than non-GE versions.
Many of these studies evaluated animals through their lives and then did histopathology and clinical chemistry workups on most of the animals’ organs. In almost every case, the range of changes they found, in animals fed GE and non-GE foods, were within normal ranges. Studies done on pigs were especially interesting because pigs are physiologically similar to humans in many ways. Many studies have been done, but they have not found significant differences between pigs fed GE and non-GE foods.
We also reviewed numerous human health studies. For example, we looked for associations between GE crops and the incidence of various types of cancer by reviewing epidemiological studies that were conducted by the National Institutes of Health. There is no obvious correlation or association between cancer incidence and the introduction of GE crops in the United States.
To look for connections with digestive diseases, especially celiac – an immune reaction to eating gluten, a protein found in wheat, barley and rye – we consulted a large database at the Mayo Clinic. Celiac disease is on the rise in the United States, but again, we found no discernible connection with the introduction of GE foods. It’s also on the rise in the United Kingdom, where people do not typically eat GE foods.
We recommend more public funding for follow-up studies in areas where early studies produced ambiguous results. This is often an issue in studies where the sample sizes are relatively small. We need public support to develop better toxicological methods in general, for both GE and non-GE foods. Our approach should be that if a food is novel, you test it. That’s how Canada regulates food, and it’s the approach that this report recommends. Test the product, not the process that created it.
I would like to see this report move the discussion away from polemics. It’s a living document. People should look at the website and contribute their ideas. Let’s have a discussion about these issues.
Peter Kareiva, Director, Institute of the Environment and Sustainability, University of California, Los Angeles; Leland Glenna, Associate Professor of Rural Sociology and Science, Technology, and Society, Pennsylvania State University, and Michael A. Gallo, Emeritus Professor of Environmental and Occupational Medicine, Rutgers University Newark