National Academies of Sciences Report on Genetically Engineered Crops: Safe to Date, No Increased Yields, Insect and Weed Resistance

The National Academies of Sciences, Engineering and Medicine (NAS) have released a report on the safety and impact of genetically engineered (GE) crops: Genetically Engineered Crops: Experiences and Prospects. This was an extensive evaluation by a committee comprised of academic experts to consider health and/or environmental effects of GE crops (note that the term "genetically modified organism/GMO" is used widely as well). As the authors described the scope of the report: 

The committee examined almost 900 research and other publications on the development, use, and effects of genetically engineered characteristics in maize (corn), soybean, and cotton, which account for almost all commercial GE crops to date. 

Here is a summary conclusion from the report:

[T]he study committee found no substantiated evidence of a difference in risks to human health between current commercially available genetically engineered (GE) crops and conventionally bred crops, nor did it find conclusive cause-and-effect evidence of environmental problems from the GE crops. 

The committee noted that the majority of GE crops in commercial use are engineered to carry just a few additional genetic traits: 

The committee used evidence accumulated over the past two decades to assess purported negative effects and purported benefits of current commercial GE crops. Since the 1980s, biologists have used genetic engineering to produce particular characteristics in plants such as longer shelf life for fruit, higher vitamin content, and resistance to diseases. However, the only genetically engineered characteristics that have been put into widespread commercial use are those that allow a crop to withstand the application of a herbicide or to be toxic to insect pests. 

The fact that only two characteristics have been widely used is one of the reasons the committee avoided sweeping, generalized statements about the benefits and risks of GE crops. Claims about the effects of existing GE crops often assume that those effects would apply to the genetic engineering process generally, but different characteristics are likely to have different effects. A genetically engineered characteristic that alters the nutritional content of a crop, for example, is unlikely to have the same environmental or economic effects as a characteristic for herbicide resistance. 

There is a reiteration of the basic U.S. regulatory paradigm, which focuses on the nature of a GE product, rather than a process-based approach:

All technologies for improving plant genetics – whether GE or conventional -- can change foods in ways that could raise safety issues, the committee’s report notes. It is the product and not the process that should be regulated, the new report says, a point that has also been made in previous Academies reports.

In determining whether a new plant variety should be subject to safety testing, regulators should focus on the extent to which the novel characteristics of the plant variety (both intended and unintended) are likely to pose a risk to human health or the environment, the extent of uncertainty about the severity of potential harm, and the potential for human exposure – regardless of whether the plant was developed using genetic-engineering or conventional-breeding processes. ” –omics” technologies will be critical in enabling these regulatory approaches.

The United States’ current policy on new plant varieties is in theory a “product” based policy, but USDA and EPA determine which plants to regulate at least partially based on the process by which they are developed. But a process-based approach is becoming less and less technically defensible as the old approaches to genetic engineering become less novel and as emerging processes — such as genome editing and synthetic biology — fail to fit current regulatory categories of genetic engineering. 

On the contentious issue of labeling food derived from GE crops (see here), the committee did not find a compelling scientific basis to require labeling, but noted that there are other considerations: 

[T]he issue involves social and economic choices that go beyond technical assessments of health or environmental safety; ultimately, it involves value choices that technical assessments alone cannot answer. 

The report therefore endorses the existing product-based framework, but coupled with a nuanced determination of what products should receive enhanced oversight. Critically, the report notes a fact which is not widely appreciated, which is that GE crops largely contain only two added traits: insect or herbicide resistance. Both of these characteristics serve agronomic ends, in contrast to alteration of product attributes, such as nutritional enhancement. As a result, the NAS committee notes that other GE traits could be introduced and require specific regulatory focus. This could be especially true when the goal of a GE alteration is a deliberate change in food composition. Finally, and not insignificantly, the committee finds that GE crops, on balance, have not led to increased yields, and notes the development of resistance in both insects and weeds. These latter conclusions will feature prominently as the cost/benefit calculus for the use of GE crops continues to be debated.