Rickinreallife's picture
Opponents of biotech enhanced crops have raised the theory that the act of alterning food crops through biotech techniques somehow introduces a novel safety risk not present with other non-regulated methods of altering the genetic endowment of food crops, whether that be conventional crossbreeding, mutigenisis (subjecting dna to mutating agents of radiation or chemicals such as how we get grapefruit), and a variety of other unregulated methods. In response to a question on this site, [http://gmoanswers.com/ask/how-can-you-presume-gmos-be-safe-when-it-was-only-recently-discovered-4-stranded-dna-exists-some] Martina Newell-McGloughlin stated that "Using modern analytical tools we can now demonstrate that all these forms of plant breeding introduce a variety of changes in DNA, ranging from point mutations and single base pair deletions and insertions, loss or acquisition of genes, to, . . . changes in numbers of whole chromosomes. By far and away the greatest changes at the molecular level are introduced by the various forms of mutation breeding." Given what we are able to know through modern analytical tools about how any form of breeding causes disruptions in the DNA and gene expression and regulation, what theories or hypothesis have been advanced by the anti-GMO community as the mechanism by which the GE process introduces novel food safety risks that isn't present in other breeding methods, and what scientific evidence is available to support or discredit these theories? Alternatively, what concerns does the biotech community have with respect to the potential to introduce undesired collateral changes through genetic engineering in plant DNA and gene expression that may have implication for human health. How can you test for and minimize the chances for this occuring.

A:Expert Answer

As mentioned previously, all breeding techniques introduce modifications at the DNA level, other than the desired change. However, I hasten to add that, despite the extensive genetic manipulation of crop plants by the many and diverse methods described previously, cases of novel or completely unexpected adverse consequences for commercialized varieties of these crops are extremely rare. Variations due to breeding and the application of modern biotechnology have been studied frequently by scientific experts sponsored by organizations such as the United Nations (UN) Food and Agriculture Organization (FAO), the European Commission, the Royal Society and the US National Academy of Sciences. In each case, the conclusions were that modern biotechnology is no more likely than conventional breeding to produce unintended effects. Indeed, many expert reviews have concluded that the greater precision and more defined nature of the changes introduced into crops via modern biotechnology may actually be safer than changes produced by conventional plant breeding.


Substantial equivalence is the guiding principle for safety assessment. In short, substantial equivalence involves the process of comparing the GM product to a conventional counterpart with a history of safe use. Such a comparison commonly includes agronomic performance, phenotype, expression of transgenes and composition (macro- and micronutrients), and it identifies the similarities and differences between the GM product and the conventional counterpart. Based on the differences identified, further investigations may be carried out to assess the safety of these differences. These assessments include any protein that is produced from the inserted DNA. In fact, several publications have demonstrated that GM crops are often more closely related to the isogenic parental strain used in their development than to other members of the same genus and species. For example, metabolomic studies in potato Solanum tuberosum have shown that conventional plant breeding produces both intended and unintended effects and that insertion of transgenes can occur with little apparent effect on composition, even when the GM variety produces significant quantities of a new metabolite (e.g., the fiber inulin). Indeed, when the introduced gene product (DP2-3 fructans) was removed from the analysis parameters, multivariate statistical analysis showed no significant variation in the metabolic phenotype, including harmful glycoalkaloids, between the GM crop and the progenitor lines, whereas other, conventionally bred cultivars showed clearly separated metabolic phenotypes (Chassy et al., 2008). Similar results have been observed at the proteome level for other plant species. So, bottom line, unexpected changes are less likely to happen using modern biotech techniques than many older breeding systems.


It is also important to keep in mind that the process of product development that selects a single commercial cultivar from hundreds to thousands of initial transformation events eliminates the vast majority of situations that might have resulted in unintended changes. The selected commercial product candidate event undergoes additional detailed phenotypic, agronomic, morphological and compositional analyses to further screen for such effects.


Chassy, B.; Egnin, M.; Gao, Y.; Glenn, K.; Kleter, G.A.; Nestel, P.; Newell-McGloughlin, M.; Phipps, R.H.; Shillito, R. 2008 Nutritional and Safety Assessments of Foods and Feeds Nutritionally Improved through Biotechnology: Case Studies Comprehensive reviews in food science and food safety 7, pp. 50–99.

Content Topics: 


Joseph Najjar's picture

Damn dude, good question! The anti-GMO community rarely picks individual issues or mechanisms to address, because in reality, there is no reputable evidence that GMOs aren't just as safe as organic crops. If you hear someone making broad, sweeping statements, ask for specifics. I bet all you will get is a change of subject. Since the biotech community has moved past the traditional ways of causing random mutations( radiation or certain chemicals), we no longer try to just cause mass mutations in order to increase the genetic variability we are selecting from. Nowadays, our capabilities to control gene expression, and our ability to screen large numbers of individuals for specific alleles, using marker assisted selection, are growing almost daily. Since DNA is DNA regardless of the source, there is no danger in ingesting actual DNA, the only possible issues would arise if gene expression caused proteins to be formed in the part of the plant that is harvested. Since this is the biggest, most plausible safety issue, it is addressed in any variety that is to be commercialized. On average, it takes over 13 years and $136 million to get a discovery all the way to the commercial market. http://www.croplife.org/PhillipsMcDougallStudy

During that time, the crops are studied extensively for their gene expression, any possible allergenic issues, as well as their impact on biodiversity and sustainability. Every case is taken on an individual basis, and the scientific community is always on the lookout for any evidence that a product may not be safe to consume. Regulations today require this testing, and the only way I can see to further minimize any chance of adverse effects would be to increase sample sizes in these late-stage tests. The more individuals in the study, the more reliable the data should be, all else being the same. Rats and pigs make good test subjects, since many of our systems are at least partially conserved.

Rickinreallife's picture

Joseph Najjar -- I tend to agree with everything you stated. When you cut through the rhetoric and spin, there is only one question regarding whether genetic engineering, i.e. splicing new genetic information into a genome (or not adding any new information but altering the genomic information to suppress or enhance gene expression) that I believe is relevant to human health. That is, "does the process disrupt a plant's genetic code in ways that would cause unintended and unknown changes in gene expression beyond the desired trait?" This is the one area where I have found ge-skeptic literature to at least be responsible and point to evidence and questions and theories that can be tested. I will even concede that undesirable collateral changes is a possibility with genetic engineering, but that is a possibility already present in plant breeding. In fact, the National Academies of Science 2010 report [Impact of Genetically Engineered Crops on Farm Sustainability in the United States ] pointed to an incident where celery resulting from non-ge hybrid crossing became extremely toxic. The regulatory process already requires an analysis of food products derived from source crops that have have ge induced traits for any changes in nutritional composition [that the food falls within norms for nutritional content for that food product], any increase in anti nutrients or naturally occurring toxins that occur in food products (people are not generally aware that a large number of foods we eat daily naturally contain trace levels of toxic substances, but usually at levels that are not of consequence or that are eliminated in cooking and processing) as well as identification of any novel proteins and analysis of their toxic or allergenic potential. When you look at the deregulation submissions, you also not that submitters also look for changes in levels of metabolites.

It seems that there is much advancement in the accuracy and sophistication of tools that profile plant genetic expressions and we are increasingly able to detect any changes that are theorized by the anti-gmo side. Also, many ge candidate plants are grown, tested and screened over several years before being placed on the market. If there were undetected adverse impacts to plant health, productivity, etc, it would likely show up at this stage and eliminated from further development.

Much of the perception that fuels anti-gmo literature is the portrayal of ge enhanced crops as some type of artificial, zombie like replica of familiar food when in fact that most applications are for agronomic values and there would be no desire to change the composition of the harvested grain, fruit, etc. I cannot understand how it is consistent with the commercial self interest of seed companies or farmers to provide or plant seeds that result in a product of inferior nutrition or that have toxic potential. If that were true, crops with biotech traits would not have survived on the market very long.

It is getting harder to claim that biotech introduces uncertainties in gene expression. This article [Evaluation of Genetically Engineered Crops Using Transcriptomic, Proteomic, and Metabolomic Profiling Techniques — http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3091128/] to a 2010 review article in Plant Physiology of a number of “omics” comparisons between ge crops and comparible non-ge varieties. As the article points out, there is a need for the scientific community to agree to standardized protocols for omics analysis, but the papers reviewed in the article appear to me to generally point toward a conclusion that recombinant techniques do not show any greater propensity for pleiotropic effects than other methods of genetic manipulation. If there were bad things happening, it should start showing up here, i.e. we would be able to see and identify exactly what change in composition would cause issues claimed to be identified in some of the gmo studies.

While I am generally convinced that the process of genetic engineering is unlikely to introduce new food safety risks, it is the applications of the technology, not the technology itself, that I sometimes criticize. Its like apps on my cellphone. Apps are not in and of themselves good or bad, but there are some apps that are trivial and perhaps not an improvement over other tools. I believe biotech has its greatest potential where it complements and supports sound resource stewardship, but is not a replacement for sound resource stewardship. I thinks the major applications of biotech have thus far had a mixed record in that respect, but overall and ultimately, I believe biotech offers numerous opportunities to advance sustainability goals.

Rickinreallife's picture

Here is an excerpt from the document linked to in my previous post.

"the experience acquired after 15 years of GE crop commercialization has comforted the validity of this [substantial equivalence] framework. However, considering the highly polarized views on GE crops, it is important to notice that the opinions expressed previously by food safety agencies (i.e. general “equivalence” of authorized GE crops with non-GE comparators) have now been independently corroborated at the transcriptomic, proteomic, and metabolomic levels by recently published omic comparisons (Table I). None of the published omic assessments has raised new safety concerns about marketed GE cultivars."

Rickinreallife's picture

Thanks for your time and insight.