Safety of Transgenic Crops

This paper investigates whether or not the research accumulated over the last 20 years is sufficient to support the safety of transgenic crops. This research  has been focused on the compositional equivalency between genetically modified (GM) crops and their non-transgenic counterparts in order to assess their human health safety. Organizations such as the European Food Safety Authority (EFSA) have prescribed intensive designs for compositional field trials to assess the safety of transgenic food. More specifically, the aims of said trials are centered in evaluating the intended gene products, typically proteins. Here, Herman and Price (2013) argue that there is overwhelming evidence that transgenesis is less disruptive to crop composition compared with traditional breeding. Furthermore, the authors ask if sufficient uncertainty still exists in the safety of transgenic crops to demand extensive safety trails, inherently slowing down the development and progression of the genetically modified food industry. Is it reasonable to expect a greater risk of negative compositional changes in GM crops compared with traditionally bred crops and is it reasonable to continue to uniquely require compositional equivalence studies for GM crops to evaluate safety? There are important questions to explore when taking into account the task of feeding a rapidly growing global population.
 Herman R., Price W. (2013) Unintended Compositional Changes in Genetically Modified (GM) Crops: 20 Years of Research. Journal of Agricultural and Food Chemistry, doi: 10.1021/jf400135r

Compositional equivalence testing for (GM) crops was designed 20 years ago in order to investigate the potential unwanted side effects of genetically engineering crops to exhibit superior and more efficient phenotypes. Traditionally, three different conditions are implemented during the field studies that assess the safety of the GM crop: the GM crop itself, a near-isogenic nontransgenic line, and one or more nontransgenic commercial reference lines. Furthermore, the GM line entries are often supplemented by cultivating them in plots treated with the herbicide to which the crop has tolerance and also in plots where this herbicide is not sprayed. Next, researchers collect plant tissue samples from each entry and analyze them for an array of nutrients and antinutrients (typically 60–80). Statistical comparisons are performed between the GM crop and the non-GM companion. If statistical differences are observed, the biological relevance of the compositional changes is evaluated by determining if the observed levels would be unsafe within the context of how the crop is produced and consumed.
                  Even more intensive compositional field trails exist, one being prescribed by the European Food Safety Authority (EFSA). According to their requirements, at least eight field sites must be used with at least four replicates per site. Furthermore, if the GM line is being tested for herbicide resistance, both sprayed and unsprayed entries must be included. Also, at least six nontransgenic reference lines must be included with at least three lines being represented at each field site. Intensive studies like this are required for both new transgenic events and combined-trait products in which two transgenic events are bred together by traditional means.
                  These expanding requirements have increased composition study costs over 10-fold during the period of 20 years since research started. Initially, a study in the United States would have cost $100,000 per study, but now that cost has skyrocketed to over U.S. $1 million per study. This is becoming an increasingly impeding barrier to the growing GM industry, not to mention that additional tests have been suggested as a requirement to the production of genetically modified foods.
                  The authors argue that traditionally bred crops are inherently safer than GM crops. Nontransgenic breeding includes intraspecific crosses, wide crosses, crosses with wild relatives, tissue culture regeneration, and mutagenesis events. These techniques have been shown to be associated with genetic mutation, deletions, insertions, and rearrangements. The fact that breeders have been purposefully selecting crops that have beneficially random mutations lends justification to transgenic crop production. In other words, transgenic modification is doing what traditional breeding does, but in a shorter amount of time. In fact, the development of recent molecular techniques and our growing understanding of genetics lay fertile ground for a prosperous and safe transgenic crop industry.  Additionally, non-transgenic crop breeding programs generally do not monitor any resulting compositional changes that might accompany a plants improved agronomic characteristic. For example, breeders selected for endogenous insect resistance, which is a process often coupled with the up-regulation of glycoalkaloids, a toxic compound that can cause sickness. Conversely, all GM varieties are routinely screened for glycoalkaloid levels to ensure their safety. Furthermore, much of our knowledge about the compositional variation that occurs in some large-acre crops such as corn, soybean, and cotton has occurred, in part, as consequence of the efforts made to evaluate the compositional safety of GM crops. Thus, this knowledge shows the added benefit of genetically modified crop development and progression.
                  It is important to consider the severity and abundance of unintended genetic effects in GM crops in comparison with those that are traditionally bred. Often, transgenic inserts are sequenced to determine if they have been inserted as intended and to confirm that they encode for the desired gene product. In addition, the portions of DNA upstream and downstream of this segment are sequenced as well to understand if any native genes or regulatory elements are disrupted. Finally, the plant genome is probed to ensure that only one insertion site exists. Conversely, traditional breeding may result in many genes randomly recombining which may lead to unwanted side-mutations. Thus, these two systems pose very different standards of regulation and safety, with genetically modified crops being the most investigated of the two.
                  The compositional safety of genetically modified crops should be considered in the context of the normal composition of the crop. Both vary in their phenotype from the composite line from which they were derived. Here, the question lies with determining whether the changes in the GM crops are more frequent, of higher magnitude, or inherently more dangerous when comparing then with traditionally bred crops. If the compositional difference is expected to differ in both the GM line and its near-isogenic counterpart, then any significant difference found between the two is just a measure of that expected difference. Rather, the authors suggest that a better safety assessment would be to evaluate if the observed level of the compositional analyte differs meaningfully from the normal array of levels observed for the aggregate crop that has a history of safe consumption. Furthermore, collecting data from increasingly larger studies likely only serves to detect small and fleeting differences that are expect and irrelevant to safety.
                  In conclusion, the 20 years of research that has been done on genetically modified crops has confirmed the compositional equivalence between GM crops and their traditionally bred counterparts. Over the past 20 years, the U.S. FDS found all of the 148 transgenic events that they evaluated to be equivalent to their conventional counterparts. Also, Japanese regulators have confirmed the same for 189 submissions. The assessment of GM foods has compiled enough information to feel confident in the future and safety of GM crops.  Unfortunately, the growing amounts of regulation and testing barriers that surround GM research greatly stunt the growth of the industry. There is significance and necessity in removing the negative stigma attributed towards genetically modified foods. With public support and reformed regulations, research on genetically modified organisms can flourish and positively affect our quality of life. 

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