GM Food Safety Q&A

Virtually every food we eat possess some kind of risk. Based on statistics by the World Health Organization, the primary risk associated with eating food is illness due to microbial contaminants, such as food-borne viruses and bacteria. WHO estimates that foodborne and waterborne diarrheal diseases taken together kill about 2.2 million people annually, 1.9 million of them children.The safety of the chemicals in food, both natural and man-made, is also an important consideration. Some are natural plant chemicals that may be toxic because they are produced by the plants to protect them against insects and other herbivores. For example, solanine, a glycoalkoloid in potatoes, is toxic to humans but naturally protects the plant with its fungicidal and pesticidal properties. Others may be unintentional contaminants such as pesticide residues. International bodies such as the Codex Alimentarius Commission, give guidelines on the maximum residue limits for pesticides in food that are considered safe to eat (http://www.codexalimentarius.net/pestres/data/index.html).

The World Health Organization/Food and Agriculture Organization (FAO), defines food to be safe if there is reasonable certainty that no harm will result from consumption under the anticipated conditions of use (CAC/GL45-2003). The FAO suggests that safety assessments should provide assurance, in the light of the best available scientific knowledge, that the food does not cause harm when prepared, used and/or eaten according to its intended use. The absolute safety of a food or an ingredient can never be guaranteed. However, with appropriate precautions during production, manufacture into products, and distribution, risk can be kept to an absolute minimum that is generally acceptable to consumers.

Genetically modified foods are not inherently less safe than their traditional counterparts. This conclusion has been reached by WHO, FAO and all National Academies of Science and established scientific authorities from around the world who have investigated this question, including countries from Europe, Asia, North and South America (e.g., International Council for Science; English, French, Italian, U.S., Mexican, Brazilian, Indian and Chinese Academies of Sciences).Nevertheless, due to lack of past experience with GM foods and concerns about novel technologies, these foods have been subjected to rigorous safety assessment procedures that are not generally applied to traditional foods. The determination of the safety of GM foods relies on a broad comparison of the properties of the GM crop to those of its conventional counterpart with a known history of safe use.The most common food safety concerns raised about GM foods include: Is it dangerous to eat foreign DNA? Can genes from GM foods be transferred to people? What is the possibility that GM foods will be allergenic? What is the possibility of novel toxins and anti-nutrients being produced in GM foods? Is there risk associated with resistance genes included in GM foods? These questions are discussed in the following sections.

All the food that we eat is derived from living organisms such as plants and animals; all living organisms contain genes which are made up of DNA. The human digestive system degrades all DNA into small fragments, whether it is from GM or conventional food. Numerous experimental studies with livestock have shown that DNA fragments or proteins derived from GM plants have not been detected in tissues, fluids or edible products of farm animals. “Therefore if one eats DNA in a GM food or a conventional food, it will not change their own DNA or that of their children” (European Food Safety Authority (EFSA), 2007; http://www.efsa.europa.eu/EFSA/Statement/EFSA_statement_DNA_proteins_gastroint.pdf).

If a new protein is introduced into a potential GM crop, its allergenic properties must be tested to ensure safety. A series of tests are performed on the protein produced by the introduced gene to identify potential allergenic effects prior to product approval. Tests are also done to be sure that the levels of naturally occurring allergens are not increased in the GM food.If a conventional food that already contains allergens is genetically engineered, the GM food will also contain those allergens, unless specific steps are taken to remove the allergens. For example, soy naturally contains proteins that cause an allergic reaction in some people. Unless these specific proteins are removed, they will also be found in GM soy varieties.

All substances, whether natural or human-made, are potentially toxic depending on the dose. Substances classified as toxins are those that can be harmful to health at typical levels of exposure. For GM products, there is concern that a new toxic substance will be introduced or the levels of toxic substances already present in the crop might be increased . The products of the new gene are tested to ensure that they are readily digested and are not toxic using simulated mammalian conditions and animal testing as needed. Levels of the naturally occurring toxins are also measured to ensure that they are not elevated above their natural levels. The GM crop is also tested to ensure that nutritional composition has not been significantly altered.

Antibiotic resistance marker (ARM) genes are commonly used to assist in the process of genetically engineering plants. There has been concern about the effect of these genes on human health and safety, if such genes present in GM foods were able to transfer to microorganisms in the human digestive tract. This question has been studied extensively by many groups (e.g., http://www.efsa.europa.eu/en/news/news/gmo070413.htm).The DNA in ARM genes are not any different from other DNA present in plants and animals. It is digested and processed in the gastro-intestinal tract just like DNA from any other source. When expressed in plant cells, the commonly used ARM genes have been shown to produce proteins that are digested in a similar way to other thousands of dietary proteins that humans consume every day. In addition, ARM proteins are frequently produced by human intestinal bacteria and thus humans have been exposed to these proteins throughout history. Therefore, it has been concluded that ARM genes themselves and the proteins they express, as with other genes and proteins in foods and feed do not pose risks to the health of humans or animals. The European Food Safety Authority has recently reaffirmed that the two antibiotic resistance marker genes, npt II and aadA, used for GM plants pose no threat to humans or the environment (EFSA, 2007).It is also important to note that the antibiotic resistance genes currently present in GM foods code for resistance to antibiotics that are not widely used in human medicine, because resistance to them is already widespread. For example the npt II gene confers resistance to neomycin, kanamycin and other antibiotics that are not in clinical use any more.

It is expected that in the future, as genetic engineering techniques evolve, antibiotic resistance genes will not be present in GM foods because they will either have been removed during development or have been replaced by other types of marker genes.

Internationally harmonized evaluation strategies have been developed to test for the safety of foods derived from genetically modified organisms (GMOs). GM- derived products, be they food, food ingredients, or foods produced by GM microorganisms, undergo more stringent safety assessment procedures than is required for non-GM foods.The approach taken is based on the concept of Substantial Equivalence (SE). SE asks whether the GM food is as safe as its traditional counterpart. (See section below for more details). On a case-by-case basis, toxicological, and nutritional investigations may be required before commercialization.The comparator approach should take into account agronomic, morphological, genetic and compositional aspects in order to make an objective assessment. Particular attention should be paid to the choice of comparator, the design of field trials, and statistical analysis of the generated data in order to obtain good comparative data. The GM crop and the comparator should be grown in the same environmental conditions to avoid genotypic and phenotypic differences not related to the transformation process (Herman et al., 2007).

An assessment of GM crops looks at the following key factors:

• Molecular characterization of the new genetic material and transformation process
• Phenotypic characterization of the new product
• Safety of new products
• Occurrence and implications of unintended effects
• Pathogenic, toxicity and anti-nutrient effect
• Allergenicity of new products
• Role of the new food in the diet
• Influence of food processing

1. Description of the Recombinant-DNA Plant
   • Identification of the crop.
   • Name of the transformation event(s).
   • Purpose of the modification, sufficient to aid in understanding the nature of the food being submitted for safety assessment.
2. Description of the Host Plant and its Use as Food
   • Common or usual name; scientific name and, taxonomic classification.
   • History of cultivation and development through breeding, in particular identifying traits that may adversely impact on human health.
   • Information on the host plant’s genotype and phenotype relevant to its safety, including any known toxicity or allergenicity.
   • History of safe use as a food.
   • How plant is typically cultivated, transported and stored.
   • Information on special processing required to make the plant safe to eat.
   • Part of the plant used as a food source.
   • Important macro- or micro-nutrients the food contributes to the diet.
   • If the food is important to particular subgroups of the population.
3. Description of the Donor Organisms
   • Common and scientific name.
   • Taxonomic classification.
   • Information about the natural history of the organism as concerns human health.
   • Information on naturally occurring toxins, anti-nutrients and allergens.
   • In case a microorganism is the donor organism, additional information on human pathogenicity and the relationship to known human pathogens.
   • Information on the past and present use, if any, in the food supply and exposure route(s) other than intended food use (e.g. possible presence as contaminants).
4. Description of the Genetic Modification(s)
   • Information on the specific method used for the modification.
   • Information on the DNA used to modify the plant including the source (e.g., plant, microbial, viral, synthetic), identity and expected function in the plant.
   • Details of all genetic components of the vector used to produce or process DNA for transformation of the host organism.
   • Information on all the genetic components including marker genes, regulatory and other elements affecting the function of the DNA.
   • Location and orientation of the sequence in the final vector/construct and function.
5. Characterization of the Genetic Modification(s)
   • Information on the DNA insertions into the plant genome including:
     • characterization and description of the inserted genetic material.
     • number of insertion sites.
     • organization of the inserted genetic material at each insertion site including copy number.
     • sequence data of the inserted material and of the flanking regions bordering the site of insertion, sufficient to identify substance (s) expressed as a consequence of the insertion.
     • identification of any open reading frames within the inserted DNA or created by the insertions with contiguous plant genomic DNA including those that could result in fusion proteins.
   • For any expressed substances in the rDNA plant the information to be provided include:
     • gene product(s) (e.g. a protein or an untranslated RNA).
     • gene product(s)’ function.
     • phenotypic description of the new trait(s).
     • level and site of expression of the expressed gene product(s) in the plant, and the levels of its metabolites in the edible portions.
     • amount of the target gene product(s), where possible, if the function of the expressed sequence(s)/gene(s) is to alter the accumulation of a specific endogenous mRNA or protein.
     • information on deliberate modifications made to the amino acid sequence of the expressed protein result in changes in its post-translational modification or affect sites critical for its structure or function.
   • Additional information to be provided:
     • demonstrate whether the arrangement of the genetic material used for insertion has been conserved.
     • show whether the intended effect of the modification has been achieved and that all expressed traits are expressed and inherited in a manner that is stable through several generations consistent with laws of inheritance.
     • demonstrate newly expressed trait(s) are expressed as expected in the appropriate tissues in a manner and at levels that are consistent with the associated regulatory sequences driving the expression of the corresponding gene.
     • any evidence to suggest that one or several genes in the host plant has been affected by the transformation process.
     • confirm the identity and expression pattern of any new fusion proteins.
     • may be necessary to examine the inheritance of the DNA insert itself or the expression of the corresponding RNA if the phenotypic characteristics cannot be measured.
6. Compositional Analyses of Key Components
   • Proximate composition including ash, moisture content, crude protein, crude fat, and various carbohydrate.
   • Protein amino acid profile.
   • Quantitative and qualitative composition of total lipids, i.e., saponifiable and nonsaponifiable components, complete fatty acid profile, phospholipids, sterols, cyclic fatty acids and known toxic fatty acids.
   • Composition of the carbohydrate fraction e.g., sugars, starches, chitin, tannins, nonstarch polysaccharides and lignin.
   • Qualitative and quantitative composition of micronutrients, i.e., significant vitamin and mineral analysis.
   • Presence of naturally occurring or adventitious anti-nutritional factors e.g., phytates, trypsin inhibitors, etc.
   • Predictable secondary metabolites, physiologically active (bioactive) substances, other detected substances.
7. Assessment of Possible Toxicity
   • Indicate if the donor organism(s) is a known source of toxins.
   • Amino acid sequence homology comparison of the newly expressed protein and known protein toxins and anti-nutrients.
   • Demonstrate the susceptibility of each newly expressed protein to pepsin digestion.
   • Where a host other than the transgenic plant is used to produce sufficient quantities of the newly expressed protein for toxicological analyses, demonstrate the structural, functional and biochemical equivalence of the non-plant expressed protein with the plant expressed protein.
   • Oral toxicity study(s) completed for newly expressed proteins.
8. Assessment of Possible Allergenicity (Proteins)
   • Indicate if the donor organism(s) is a known source of allergens.
   • Amino acid sequence homology comparison of the newly expressed protein and known allergens.
   • Demonstrate the susceptibility of each newly expressed protein to pepsin digestion.
   • Where a host other than the transgenic plant is used to produce sufficient quantities of the newly expressed protein for toxicological analyses, demonstrate the structural, functional and biochemical equivalence of the non-plant expressed protein with the plant expressed protein.
   • For those proteins that originate from a source known to be allergenic, or have sequence homology with a known allergen, additional immunological assays be warranted.