2.11—Biological variability is typical of crop varieties

No meaningful changes in nutrients or toxicants have been observed in GM crops

See Genetic Roulette’s False Claims at Bottom of Page

Analysis of Peer-Reviewed Research:

Genetic Roulette makes a long series of claims intended to establish that GM crops have unexpectedly been found to have differences in composition from their conventional counterparts and that in some cases investigators were surprised by the composition they observed in a newly prepared GM crop.  There is no doubt that surprises happen in science, that’s why we talk about research and the discovery process.  That said, some of the events Smith describes should have come as no surprise to the scientists who saw them.  Before a GM crop is placed on the market its composition is carefully evaluated. GM crops are not approved if the composition analysis doesn’t show that they are as safe and nutritious as other varieties of the same crop.  The very robust analysis that is applied to GM crops is not applied to conventional crops.  This is paradoxical since studies have now shown that conventional crops are more varied in composition than GM crops, and that conventional breeding produces more unintended change than precise GM methods (e.g. Beckmann and other s2007; Catchpole and others 2005).  If Smith were really concerned about food safety and not just bashing GM foods, he would do well to turn his attention to the thousands of conventional varieties of foods that have not been subjected to the careful analysis and close scrutiny applied to GM crops.

1. Living plants display significant biological variation in composition. Variation in the composition of food is normal, and is a risk associated with conventional breeding that has seldom caused problem for food consumers. Several conventional foods, including potatoes, tomatoes, celery and cassava, have known toxic compounds in them. Potatoes for instance are well established to display huge variations in specialized chemical content and to contain nerve toxins (Beckmann and others 2007). Other foods, such as peanuts and kiwifruit are sources of allergens. These potentially hazardous conventional foods can be managed safely by appropriate precautions (NAS 2004, Knudsen 2008, Cellini and others 2004).

2. Unexpected compositional changes in transgenic crops are negligible compared to the natural variation. Comprehensive chemical analysis of GM food components has been carried out by measurement of all the detectable components of these foods crops. These profiles of protein, RNA and metabolite composition prove that insertion of a transgene has much less effect on composition than does conventional breeding.   Varieties of conventionally bred crops have displayed more differences in composition than do GM crops. This proof of negligible unexpected changes is available for several genetically modified foods.  The references cited by Smith conclude that the composition of GM crops is within normally expected ranges.  In no case do they call safety into question (Baker and others 2006, Catchpole and others 2005, Ioset  and others 2007, Kärenlampi and Lehesranta 2006, Lemaux  2008. Section 3.6. , Padgette and others 1996, Sautter and  Urbaniak  2007, Shewry and others 2007).

Some of the most decisive work in this direction has been funded by the UK Food Safety Authority (Catchpole and others 2005). This looked at deliberate genetic manipulation of chemical content of potatoes and involved a thorough survey of 230 different metabolites in the potatoes. It concluded that the only changes from genetic manipulation that were seen were those that were predicted based on biochemical understanding of how metabolism works. Comprehensive and valuable reports on this topic are published by that authority (FSA 2005). The more recent of those reports are not cited by Smith, and they provide abundant evidence that any changes in metabolites resulting from transgene insertion fall within the range of changes seen with conventional varieties of crops.

3. Safety assessments carried out on GM foods always evaluate potential toxicants and allergens. In fact since the known toxic components or potentially toxic components present in the foods (such as glucosinolate content or isoflavone content) are a required part of the premarket safety assessment process for GM foods, but is no required everywhere for conventional foods, GM crops are most likely safer from a compositional point of view (Knudsen I  and others 2008).  In the early days of GM crop approvals there were no internationally accepted norms the specified what should be measured in each crop.  As a result, the composition analyses supplied with early approvals (in the 1990s) weren’t always the same.  In recent years, the compostion analysis data supplied to regulators around the world has followed internationally accepted standards for each crop—see for example the OECD consensus documents. OECD (2001-2008) www.oecd.org/document/9/0,3343,en_2649_34391_1812041_1_1_1_1,00.html accessed Dec 21 2008.

4. Unexpected changes in composition of food can occur for reasons unrelated to genetics (Padgette and others 1996; NAS 2004; Wang and Murphy 1994). Many factors can lead to differences in composition.  For example, damage caused by insect pests, water stress caused by lack of rainfall, or changes in cultivation and other farming practices. Prior to approval GM crops are typically grown alongside conventional varieties at 3 to 6 widely separated geographical sites and the food or feed product harvested over 2 or 3 growing seasons. The composition of GM crops is determined in these carefully controlled studies.  No GM crop on the market today in the world has a biologically meaningful difference in composition—in fact, the composition of every measured component is within the range normally observed for that component in that crop.  The presence of variation in the content of a food component level does not mean that a genetically engineered food exhibits more risk than a conventional food variety.  One must also be careful to ensure that observed differences are genetic rather than cultural.

5. The biological variation in composition of foods is the reason why its safety assessments have to be comparative.  That is to say, the safety of any food, such as a GM food, has to be assessed by comparing it with the compositional safety of a conventional food.  Comparison against several varieties is recommended (Konig and others 2004).

6. GM crops may be safer than conventional crops. Many traditional foods, despite their general history of safe use, have not been systematically evaluated for chemical safety, even though they are known to contain potentially harmful components such as allergens and toxins (Knudsen 2008).

7.  Genetic Roulette gives incomplete and inaccurate accounts of differences in GM crops. Smith cites a long list of papers that he claims show the fundamental uncertainty in GM technology.  These papers fall into several categories: 1) papers that involve early research using GM technology in which unexpected results occurred.  In many of the cited cases investigators could have anticipated the changes and in other cases something new was learned—that’s the nature of research, 2) also mentioned are various studies that document what turned out on later analysis not to be real or meaningful differences(eg. Padgette and others 1996).  Of course things don’t always work as planned in research (that’s why we call it research), but when negative differences that are related to safety or performance are noted, products are not marketed.  The fact that we can find differences means the safety system works.

8.  It is not necessary to analyze every component of a food to know that it is safe to eat. Genetic Roulette attempts to make a case that we don’t analyze every component in a food or feed so that many undetected changes could have taken place.  While the analysis is much more sophisticated and complete than Smith would have readers believe, it is true that not every component of a food is analyzed.  Scientists analyze the compounds that are important in a food, often 100-150 separate compounds.  These include all macro-nutrients (protein, carbohydrate, and fats), vitamins, minerals, individual amino acids, total lipid composition and all known allergens, anti-toxicants and other compounds of biological interest (for example, isoflavones in soy because they may have health benefits).  The analysis accounts for 99+% of what’s in the food, and more importantly, it accounts for all compounds with known biological significance in that food.  It is also the case that in a cell, metabolic pathways are interconnected with one another.  If a large number of compounds are found to within their normal range of variability, making allowances for environmental and processing effects, then it is highly unlikely that other compounds will be significantly different in abundance. Exceptions to this argument are indeed possible, given there are large numbers of possible compounds present in plant tissues, but there are more opportunities for unexpected problems from conventional breeding and there are from genetic engineering, given the now rapidly accumulating evidence that conventional breeding produces larger changes in composition than does the more precise and less disruptive technique of gene insertion (see references for item 2 above).  Finally, the foods and feeds that are cultivated in the world today are inherently safe to eat.


Baker JM and others (2006). A metabolomic study of substantial equivalence of field-grown GM wheat. Plant Biotechnology Journal, 4:381-392. GM and non-GM wheats have the same metabolite levels.

Beckmann Manfred, David P. Enot, David P. Overy, and John Draper (2007). Representation, comparison, and interpretation of metabolome fingerprint data for total composition analysis and quality trait Investigation in potato cultivars. J. Agric. Food Chem. 55 (9): 3444-3451 DOI: 10.1021/jf0701842. Institute of Biological Sciences, Edward Llwyd Building, University of Wales, Aberystwyth, Ceredigion SY23 3DA, United Kingdom

Catchpole GS and others (2005). Hierarchical metabolomics demonstrates substantial compositional similarity between genetically modified and conventional potato crops. PNAS October 4, 2005 vol. 102 no. 40 14458-14462

Cellini F and others (2004). Unintended effects and their detection in genetically modified crops. Food and Chemical Toxicology 42:1089-1125. Unintended effects are those outcomes that are totally unexpected and not predictable. This paper focuses on technology for detection of such unexpected outcomes, and this includes metabolomics, proteomics, and transcriptomics. These buzzwords correspond to various forms of chemical fingerprinting.

EFSA GMO Panel Working Group on Animal Feeding Trials. (2008). Safety and nutritional assessment of GM plants and derived food and feed: the role of animal feeding trials. Food Chemistry and Toxicology 46 Suppl 1:S2-70. Epub 2008 Feb 13. Review. Comprehensive and authoritative review of the state of play with animal feeding trials carried out with genetically modified crops, including discussion of their strengths and weaknesses. Experts associated with the European Food Safety Authority provide a comprehensive listing of many animal feeding tests and in-depth technical analysis of their interpretation.

Kärenlampi S O and Lehesranta S J (2006) Proteomic profiling and unintended effects in genetically modified crops. ISB News Report January 2006. www.isb.vt.edu/news/2006/news06.Jan.htm accessed Dec 200 2008. One of many papers on the comprehensive study of the total protein profiles of plants.

NAS (2004) Safety of Genetically Engineered Foods: Approaches to Assessing Unintended Health Effects by Food and Nutrition Board (FNB) Institute of Medicine (IOM) Board on Agriculture and Natural Resources (BANR) Board on Life Sciences (BLS)). National Academies Press. books.nap.edu/openbook.php?isbn=0309092094 accessed Dec 21 2008.

Ioset JR and others (2007). Flavonoid profiling among wild type and related GM wheat varieties. Plant Molecular Biology 65 (5), 645-654

Knudsen I, Soborg I, Eriksen F, and others (2008). Risk management and risk assessment of novel plant foods: Concepts and principles. Food and Chemical Toxicology 46:1681-1705. Compared to genetically modified food very little is known about potential long-term health effects of any traditional food, according to this report.

Konig A, Cockburn A, Crevel RWR and others (2004). Assessment of the safety of foods derived from genetically modified (GM) crops. Food and Chemical Toxicology 42:1047-1088. Provides a framework of methods and approaches for ensuring that genetically modified foods are safe, from a large group of experts from both the public and private sectors, predominantly European.

OECD (2001-2008) Consensus Documents for the work on the Safety of Novel Foods and Feeds www.oecd.org/document/9/0,3343,en_2649_34391_1812041_1_1_1_1,00.html accessed Dec 21 2008

Lemaux P (2008). Section 3.4. Are Food safety studies conducted on GE foods? In Review: Genetically engineered plants and foods: a scientist’s analysis of the issues (Part I). Annual Review Plant Biology 59:771–812.

Lemaux P (2008). Section 3.6.  Do genetically engineered foods have changes in nutritional content? In Review: Genetically engineered plants and foods: a scientist’s analysis of the issues (Part I). Annual Review Plant Biology 59:771–812. Discusses the need to assess normal range of variation in plant composition when deciding whether genetic engineering causes changes. Provides key references to studies on comparative composition.

Padgette SR and others (1996). The composition of glyphosate-tolerant soybean seeds is equivalent to that of conventional soybeans. J. Nutr. 126:702–16

Sautter C & Urbaniak B (2007). Flavanoids for environmental equivalence profiling of GE plants ISB News Report. December 2007. www.isb.vt.edu/news/2007/artspdf/dec0703.pdf pdf file accessed Dec 21 2008

Shepherd LVT and others (2006). Assessing potential for unintended effects in genetically modified potatoes perturbed in metabolic and developmental processes. Targeted analysis of key nutrients and antinutrients. Transgenic Res. 15:409–25. Demonstration that key nutrients and antinutrients in genetically engineered potatoes are substantially equivalent.

Shewry PR and others (2007). Are GM and conventionally bred cereals really different? Trends Food Sci. Technol. 18:201–9

Taylor NB and others (1999). Compositional analysis of glyphosate-tolerant soybeans treated with glyphosate Journal of Agricultural and Food Chemistry 47 (10):4469-4473. DOI: 10.1021/jf990056g. Other studies had shown that GM and non-GM soybeans compositionally equivalent. This study shows that glyphosate treated soybeans are compositionally equivalent to non-treated soybeans.

Wang H-J and Murphy PA (1994). Isoflavone composition of American and Japanese soybeans in Iowa: Effects of variety, Crop year, and location J. Agric. Food Chem. 42:1674-1677. Total isoflavone content varies over a 400% range.

Genetic Roulette Falsely Claims:

GM crops have altered levels of nutrients and toxins

  1. Numerous studies on GMO’s reveal unintended changes in nutrients, toxins, allergens, and small molecule products of metabolism.
  2. These demonstrate the risk associated with unintended changes that occur due to genetic engineering.
  3. Safety assessments are not adequate to guard against potential health risks associated with these changes.

Genetic Roulette claims that changes in nutrients, toxins and allergens in genetically engineered crops are risks that cannot be managed by safety assessment.

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