Food Safety And Substantial Equivalence

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Issue in Brief:
Biotech Foods Are Rigorously Tested to Ensure Safety

Americans enjoy a food supply that is among the safest in the world. However, concerns have been expressed that biotech food products threaten the safety of the food supply.

There is no reason to believe that biotech foods pose a greater threat to human health than conventional foods. This is not to say they are risk free, but that they pose the same types of inherent risks to human health as conventional foods, e.g., they can contain allergens, toxins and antinutrients. Before marketing a biotech food, company scientists evaluate these risks, which are not usually evaluated in conventional foods. Animal feeds also are evaluated.

In fact, many scientists believe biotechnology may actually improve the safety testing of new foods. Consider that traditional breeding methods usually involve the mixing of tens of thousands of genes. While backcrossing can remove many undesirable qualities, there are still many uncharacterized genetic changes. For example, traditionally bred varieties of potato and celery were found to produce unacceptably high levels of toxins after they had already been put on the market.

With biotechnology, only a small amount of genetic material is transferred, and scientists know a great deal more about the changes being made. As a result, they are in a much better position to assess safety. For example, in the 1990s one biotech firm tried to improve the protein content of a soybean variety by transferring a gene from the Brazil nut. Subsequent testing showed that this gene encoded for an allergen, and the project was halted. Often cited as an example of what can go wrong, it demonstrates instead how good testing and knowing what to look for can lead to even greater safety. Indeed, plants and foods produced using biotechnology are among the most stringently tested in history.

Substantial Equivalence
Genetic manipulation by any means can lead to unexpected or seemingly unrelated changes in a food. These are the focus of any safety assessment. Under federal law, food producers have the legal responsibility to ensure that their products are safe to consume, and the Food and Drug Administration and Environmental Protection Agency (for pest-protected plants) both have regulatory oversight authority. The food safety assessment for biotech products, whether performed by the FDA or the EPA, requires evaluation of the safety of the newly added DNA, its protein products and the overall balance of the food.

Guiding this assessment is the concept of "substantial equivalence," which was introduced by the Organization for Economic Cooperation and Development in 1993. Substantial equivalence is widely regarded as a sound basis for safeguarding the quality and safety of biotech foods and provides an historical context based on centuries of experience with conventional foods. In addition to the OECD, this standard has been validated by many international scientific and governmental organizations, including the U.N. Food and Agriculture Organization and World Health Organization and the International Life Science Institute. The FDA's 1992 Statement on Policy on biotech foods, which lays out the agency's approach to biotech regulation, is consistent with substantial equivalence, and many other government regulatory agencies also have adopted it in their regulatory reviews.

Stated simply, substantial equivalence holds that a biotech food is as safe to consume as an existing food with the same compositional and nutritional characteristics and a history of safe use. The main food-safety issues for biotech varieties crops are changes in allergenicity, toxicity, nutrient composition and level, unintended effects, and the safety of antibiotic-resistant marker-encoded proteins included with the transgene. This evaluation seeks to establish that the new varieties are as safe as or safer than crops produced by traditional methods.

Evaluating the substantial equivalence of a new food involves measuring the bioavailability and concentration of important nutrients in the food-such as proteins, carbohydrates, vitamins, minerals, fats and oils-to ensure that they fall within the normal range of variability for the food. As many foods contain naturally occurring toxins and antinutrients, levels of these substances also are tested and compared. Immunological testing also is conducted. In contrast, there are relatively few analytical studies done on conventional varieties of crops during development.

Substantial equivalence is not the end of the safety assessment, but the beginning. The results of these analyses can yield three conclusions. The new food may be found: 1) substantially equivalent to a conventional counterpart; 2) substantially equivalent except for a few clearly defined differences; and 3) not substantially equivalent. Any significant differences between the biotech food and its conventional counterpart would trigger additional tests and mandatory labeling.

Some have contended that substantial equivalence overlooks effects that may be caused by the genetic transformation process itself, and therefore toxological testing of the whole food is required. In a controversial 1999 toxilogical study published in the British journal The Lancet, rats were fed a diet solely of either potatoes bioengineered to produce lectin (an insecticide), potatoes spiked with lectin, or wild potatoes. The researchers reported physiological damage for the first group only, leading them to conclude that the transformation process itself was responsible for the reported physiological changes.

Although much was initially made of this study, many scientists see it as seriously flawed. The decision to publish this study was even questioned by The Lancet's editors, who noted that it was rejected by half of the peer reviewers. Many of the authors' initial claims also were removed because they were unsupportable. Publication, said the editors, was "absolutely not a vindication" of the claims made by the authors. No subsequent research has reproduced the reported effects.

Toxilogical testing of whole foods is not performed on either biotech or conventional crops. Experts believe such tests are not feasible and would be of little value. A regulatory approach employing substantial equivalence ensures that biotech foods are at least as safe as their conventional counterparts.

In the future, biotech products will be designed with enhanced nutrition, taste, or other attribute that consumers want. Testing based largely on substantial equivalence will assure their safety and value.

Regulatory Oversight
Before a biotech food is submitted to regulators for approval, it has already undergone a series of tests by the food developer. The FDA has established guidelines that biotechnology companies follow when conducting safety reviews of new foods. These reviews include an assessment of toxicants, allergens and nutrient levels. If the original plant and the transferred trait have been consumed in the past without negative consequences, they are considered "generally recognized as safe" by the FDA.

If the original food or the transferred protein is new to the food supply, or if the transferred protein was derived from a food known to harbor allergens or toxicants, extensive testing is required. The FDA also reviews data on the nutrient content. Significant changes in nutrient levels of a new biotech food, compared with its traditional counterpart, would trigger a formal FDA review. Thus far, all biotech foods reviewed by FDA have exhibited compositional and nutritional characteristics within the normal range of variability, and peer-reviewed research has demonstrated the essential equivalence of biotech food and feed products and their conventional counterparts.

In cases where a trait is derived from a known allergen or the nutrient level is significantly different from comparable traditional foods, the FDA requires a special food label. Biotechnology companies now avoid using genes from foods known to harbor allergens or toxins. (For more information on biotechnology and allergenicity, click here.)

The EPA also regulates the safety of foods derived from pest-protected plants. For example, the proteins expressed in Bt crops, which incorporate genetic material from the common soil bacterium Bacillus thuringiensis, are thoroughly tested to ensure that they do not pose a health risk.

In fact, Bt corn has been shown to reduce exposure to harmful substances. The fungus Fusarium moniliforme is known to thrive in corn damaged by the corn ear worm. Fusarium produces a mycotoxin, fumonisin, linked to esophageal cancer. Bt corn controls the corn ear worm, which makes it more difficult for Fusarium to establish itself.

For more on U.S. regulation of biotech crops and foods, click here.

Antibiotic Resistance
Another area of concern has been the use of antibiotic resistance markers in developing new plants. Antibiotic resistance is a growing problem in medicine, and there is a fear that horizontal transfer of antibiotic resistance genes to harmful bacteria in the human digestive tract could hasten the development of resistant bacterial strains, rendering some antibiotics useless.

Although antibiotic markers have been employed to produce most of the biotech plants currently on the market, they pose little to no risk. Antibiotic markers are used to trace introduced DNA and determine if a desired transfer was successful. However, their transfer to bacteria in the human gut is practically inconceivable for a number of reasons. For a successful DNA transfer from a plant food to a bacterium, a series of extremely unlikely events would have to occur: the DNA would have to survive digestion; the gene would have to breach the bacterium's defense; and it would have to be incorporated in the bacterium's DNA in exactly the right sequence. In the extremely improbable event that a successful exchange were to occur, selection pressure from an antibiotic would be required to make the newly resistant strain a common one.

The FDA examined this issue and determined that this procedure is safe. Further, no one has been able to demonstrate that such a transfer can occur, despite numerous experimental attempts to initiate one. In any event, scientists are developing alternative marker genes that do not involve antibiotic resistance, and biotechnology companies are removing all antibiotic resistance genes before a biotech crop is released.

Biotech Food and Feed Are Safe
In the many years in which biotech foods have been consumed, there has been no evidence that they are less safe than their conventional counterparts. In a 2000 report, a committee of the National Academies noted, "The committee is not aware of any evidence that foods on the market are unsafe to eat as a result of genetic modification," and other groups have reached similar conclusions. Because scientists know more about the changes being made when using biotechnology, plant breeders have a greater understanding of the changes being made, which places them in a better position to address food-safety issues. Rigorous testing from product development through commercialization will ensure that biotech products remain safe.

Resources:
Safety of Biotech Foods:

• Center for Food Safety and Applied Nutrition.
• "Statement on Policy: Foods Derived from New Plant Varieties; Notice," Federal Register May 29, 1992, 57(104): 22984-23001.

• Office of Pesticide Programs, Biopesticides.

• Report of the Task Force for the Safety of Novel Foods and Feeds (May 31, 2000).
  Available in English and French.
• GM Food Safety: Facts, Uncertainties, and Assessment, The OECD Edinburgh Conference on the Scientific and Health Aspects of Genetically Modified Foods (February 28-March 1, 2000).
• Genetically Modified Foods: Widening the Debate on Health and Safety, Reports from the OECD Edinburgh Conference on the Scientific and Health Aspects of Genetically Modified Foods and the OECD Consultation with Nongovernmental Organizations on Biotechnology and Other Aspects of Food Safety (January 1, 2000).
• Safety Evaluations for Foods Derived by Modern Biotechnology: Concepts and Principles (1993).
• Consensus Documents for the Work on the Safety of Novel Foods and Feeds.

• Joint FAO/WHO Consultations on Food Derived from Biotechnology.
• WHO, 20 Questions on Genetically Modified (GM) Foods.

• The Safety Assessment of Novel Foods, Guidelines, ILSI Europe Novel Food Task Force (1995).
• Safety Considerations of DNA in Foods, ILSI Europe Novel Food Task Force (2001).
• International Documents and Scientific Publications on Plant Biotechnology and the Safety Assessment of Food Products Derived from Plant Biotechnology (2002).

• AgBioWorld, Scientific Journal Articles: General Safety and Safety Assessment of Specific Genetically Modified Crops.
• American Council on Science and Health, Biotechnology and Food (2000).
• American Medical Association Council on Scientific Affairs, Genetically Modified Crops and Foods (I-00) Full Text (2000).
• Donald J. MacKenzie, International Comparison of Regulatory Frameworks for Food Products of Biotechnology, Canadian Biotechnology Advisory Committee Project Steering Committee on the Regulation of Genetically Modified Foods (December 2000).
• European Union, EC-Sponsored Research on the Safety of Genetically Modified Organisms: A Review of Results (2001).
• Ewan, S., and Pusztai, A. 1999. Effect of diets containing genetically modified potatoes expressing Galanthus nivalis lectin on rat small intestine. Lancet 354: 1353-1355.
• General Accounting Office, Genetically Modified Foods - Experts View Regimen of Safety Tests as Adequate, but FDA's Evaluation Process Could Be Enhanced, GAO-02-566 (May 2002).
• Mae-Wan Ho and Ricarda A. Steinbrecher, Fatal Flaws in Food Safety Assessment: Critique of The Joint FAO/WHO Biotechnology and Food Safety Report, Third World Network.
• Hodgson, E. 2001. Genetically modified plants and human health risks: Can additional research reduce uncertainties and increase public confidence? Toxicological Sciences 63: 153-156.
• Institute of Food Technologists, "Human Food Safety," Expert Report on Biotechnology and Food (2000).
  Food safety chapter, a one-page chapter summary and an IFT backgrounder on food safety available.
• Journal of the American College of Nutrition, The Future of Food and Nutrition with Biotechnology, Supplement 21(3S), June 2002.
  Read the article abstracts here.
• Kuiper, H.A., et al. 2001. Assessment of the food safety issues related to genetically modified foods. The Plant Journal 27(6): 503-528.
• Millstone, E., Brunner, E., and Mayer, S. 1999. Beyond 'substantial equivalence.' Nature 401: 525-526.
• National Academies of Science, National Research Council, Genetically Modified Pest-Protected Plants: Science and Regulation (2000).
• Nordlee, J.A., et al. 1996. Identification of a Brazil-nut allergen in transgenic soybeans. New England Journal of Medicine 334: 668-693.
• Royal Society, Genetically Modified Plants for Food Use and Human Health-An Update (February 2002).

• Food and Drug Administration, Guidance for Industry: Use of Antibiotic Resistance Marker Genes in Transgenic Plants (September 4, 1998).
• Abigail Salyers. Genetically engineered foods: Safety issues associated with antibiotic resistance genes. Reservoirs of Anti-biotic Resistance Network (2000).

• Minorsky, P.V. 2002. Fumonisin mycotoxins. Plant Physiology 129: 929-930.
• Munkvold, G.P. and Hellmich, R.L. 1999. Genetically modified, insect-resistant corn: Implications for disease management. APSnet Feature (October-November).
• Munkvold, G.P., and Hellmich, R.L. 1999. Comparison of fumonisin concentrations in kernels of transgenic Bt maize hybrids and nontransgenic hybrids. Plant Disease 83 (2): 130-138.

• Federation of Animal Scientific Societies, FASS Facts on Biotech Crops-Impact on Meat, Milk and Eggs (2001).
• Federation of Animal Scientific Societies, References-Feeding Transgenic Crops to Livestock.

For more links, click here.

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