Languages:

Genetically Modified Crops

4. Are genetically modified plant foods safe to eat?

  • 4.1 Could genetically modified plant foods have health effects?
    • 4.1.1 Allergies and toxicity
    • 4.1.2 Antibiotic and herbicide-resistance
    • 4.1.3 Health benefits
  • 4.2 How should genetically modified food safety be assessed?
  • 4.3 How should genetically modified foods be labelled in the market place?

4.1 Could genetically modified plant foods have health effects?

    • 4.1.1 Allergies and toxicity
    • 4.1.2 Antibiotic and herbicide-resistance
    • 4.1.3 Health benefits

The source document for this Digest states:

The scientific evidence concerning the environmental and health impacts of genetic engineering is still emerging. This chapter briefly summarizes the current state of scientific knowledge on the potential health and environmental risks (Box 17) associated with genetic engineering in food and agriculture, followed by a discussion of the role of international standard-setting bodies in harmonizing risk analysis procedures for these products (Box 18). The scientific evidence presented in this chapter relies largely on a recent report from the International Council for Science (ICSU, 2003 - referred to hereafter as ICSU). The ICSU report draws on 50 independent scientific assessments carried out by authoritative groups in different parts of the world, including the FAO/WHO Codex Alimentarius Commission, the European Commission, the OECD and the national science academies of many countries such as Australia, Brazil, China, France, India, the United Kingdom and the United States. In addition, this chapter draws on recent scientific evaluations from the Nuffield Council on Bioethics (2003 - referred to hereafter as Nuffield Council), the United Kingdom GM Science Review Panel (2003 - referred to hereafter as GM Science Review Panel) and the Royal Society (2003 - referred to hereafter as Royal Society) that were not available when the ICSU report was prepared. There is a substantial degree of consensus within the scientific community on many of the major safety questions concerning transgenic products, but scientists disagree on some issues, and gaps in knowledge remain.

Source & ©: FAO "The State of Food and Agriculture 2003-2004"
Chapter 5: Health and environmental impacts of transgenic crops 

Food Safety implications

Currently available transgenic crops and foods derived from them have been judged safe to eat and the methods used to test their safety have been deemed appropriate. These conclusions represent the consensus of the scientific evidence surveyed by the ICSU (2003) and they are consistent with the views of the World Health Organization (WHO, 2002). These foods have been assessed for increased risks to human health by several national regulatory authorities (inter alia, Argentina, Brazil, Canada, China, the United Kingdom and the United States) using their national food safety procedures (ICSU). To date no verifiable untoward toxic or nutritionally deleterious effects resulting from the consumption of foods derived from genetically modified crops have been discovered anywhere in the world (GM Science Review Panel). Many millions of people have consumed foods derived from GM plants - mainly maize, soybean and oilseed rape - without any observed adverse effects (ICSU).

The lack of evidence of negative effects, however, does not mean that new transgenic foods are without risk (ICSU, GM Science Review Panel). Scientists acknowledge that not enough is known about the long-term effects of transgenic (and most traditional) foods. It will be difficult to detect long-term effects because of many confounding factors such as the underlying genetic variability in foods and problems in assessing the impacts of whole foods. Furthermore, newer, more complex genetically transformed foods may be more difficult to assess and may increase the possibility of unintended effects. New profiling or “fingerprinting” tools may be useful in testing whole foods for unintended changes in composition (ICSU).

The main food safety concerns associated with transgenic products and foods derived from them relate to the possibility of increased allergens, toxins or other harmful compounds; horizontal gene transfer particularly of antibiotic-resistant genes; and other unintended effects (FAO/WHO, 2000). Many of these concerns also apply to crop varieties developed using conventional breeding methods and grown under traditional farming practices (ICSU). In addition to these concerns, there are direct and indirect health benefits associated with transgenic foods that should be more fully evaluated.

Source & ©: FAO "The State of Food and Agriculture 2003-2004"
Chapter 5: Health and environmental impacts of transgenic crops 
Section Food safety implications

4.1.1 Allergies and toxicity

The source document for this Digest states:

Allergens and toxins

Gene technology - like traditional breeding - may increase or decrease levels of naturally occurring proteins, toxins or other harmful compounds in foods. Traditionally developed foods are not generally tested for these substances even though they often occur naturally and can be affected by traditional breeding. The use of genes from known allergenic sources in transformation experiments is discouraged and if a transformed product is found to pose an increased risk of allergenicity it should be discontinued. The GM foods currently on the market have been tested for increased levels of known allergens and toxins and none has been found (ICSU). Scientists agree that these standard tests should be continuously evaluated and improved and that caution should be exercised when assessing all new foods, including those derived from transgenic crops (ICSU, GM Science Review Panel).

Source & ©: FAO "The State of Food and Agriculture 2003-2004"
Chapter 5: Health and environmental impacts of transgenic crops 
Subsection Allergens and toxins

4.1.2 Antibiotic and herbicide-resistance

The source document for this Digest states:

Antibiotic resistance

Horizontal gene transfer and antibiotic resistance is a food safety concern because many first-generation GM crops were created using antibiotic-resistant marker genes. If these genes could be transferred from a food product into the cells of the body or to bacteria in the gastrointestinal tract this could lead to the development of antibiotic-resistant strains of bacteria, with adverse health consequences. Although scientists believe the probability of transfer is extremely low (GM Science Review Panel), the use of antibiotic-resistant genes has been discouraged by an FAO and WHO expert panel (2000) and other bodies. Researchers have developed methods to eliminate antibiotic-resistant markers from genetically engineered plants (Box 20).

Source & ©: FAO "The State of Food and Agriculture 2003-2004"
Chapter 5: Health and environmental impacts of transgenic crops 
Section Food Safety implications, Subsection Antibiotic resistance

BOX 20
“Clean gene” transformation at CIMMYT
Since the introduction of GM crops, a part of civil society has expressed concern about the antibiotic- and herbicide-resistance genes used as selectable marker genes in the development of transgenic plants. They cite potential ecological and health hazards, specifically the evolution of “superweeds” from herbicide resistance and the build-up of resistance to antibiotics in human pathogens. Although most scientists believe that these concerns are largely unfounded, and neither hazard has actually materialized, the development of marker-gene-free transgenics would help defuse such concerns and could contribute to the public acceptance of transgenic crops (Zuo et al., 2002).

Several methods have been reported to create transformed plants that do not carry marker genes, for example co-transformation (Stahl et al., 2002), transposable elements (Rommens et al., 1992), site-specific recombination (Corneille et al., 2001) and intrachromosomal recombination (De Vetten et al., 2003). The International Maize and Wheat Improvement Center (known by its Spanish acronym, CIMMYT) is committed to providing resource-poor farmers in developing countries with the best options for implementing sustainable maize and wheat systems. CIMMYT believes that although GM crops will not solve all of the problems faced by farmers, the technology does have great potential and should be evaluated.

Scientists at CIMMYT have developed and adapted a transformation technique for wheat and maize to produce genetically modified plants that do not carry the selectable marker genes. With this technique, two DNA fragments, one containing the selectable marker gene and the other containing the gene of interest, are introduced and integrated separately into the genome. During the selection process, these genes segregate from each other, allowing the selection of the plants with only the gene of interest. CIMMYT scientists tested this simple technique using the selectable gene bar and the Bt genes, Cry1Ab and Cry1Ba, and successfully obtained plants without the selectable marker gene but with the Bt gene and which expressed high levels of Bt toxin. Transgenic plants were morphologically indistinguishable from untransformed plants and the introduced trait was inherited stably in the subsequent generations.

Efforts are now under way with the Kenya National Agricultural Institute and the Syngenta Foundation for Sustainable Agriculture to transfer these “clean events” to local varieties of maize in Kenya to provide resource-poor farmers with an additional option for insect control in the form they know best - the seed they plant. A similar approach is being used to enhance other important traits, such as abiotic stress tolerance and micronutrient content. Improved tolerance to stresses such as drought would directly benefit farmers, and biofortified plants could have a significant impact on children's health in developing countries.

Source & ©: FAO "The State of Food and Agriculture 2003-2004"
Chapter 5: Health and environmental impacts of transgenic crops , Box 20

Other unintended changes

Other unintended changes in food composition can occur during genetic improvement by traditional breeding and/or gene technology. Chemical analysis is used to test GM products for changes in known nutrients and toxicants in a targeted way. Scientists acknowledge that more extensive genetic modifications involving multiple transgenes may increase the likelihood of other unintended effects and may require additional testing (ICSU, GM Science Review Panel).

Source & ©: FAO "The State of Food and Agriculture 2003-2004"
Chapter 5: Health and environmental impacts of transgenic crops 
Section Food Safety implications, Subsection Other unintended changes

4.1.3 Health benefits

The source document for this Digest states:

Potential health benefits of transgenic foods

Scientists generally agree that genetic engineering can offer direct and indirect health benefits to consumers (ICSU). Direct benefits can come from improving the nutritional quality of foods (e.g. Golden Rice), reducing the presence of toxic compounds (e.g. cassava with less cyanide) and by reducing allergens in certain foods (e.g. groundnuts and wheat). However, there is a need to demonstrate that nutritionally significant levels of vitamins and other nutrients are genetically expressed and nutritionally available in new foods and that there are no unintended effects (ICSU). Indirect health benefits can come from reduced pesticide use, lower occurrence of mycotoxins (caused by insect or disease damage), increased availability of affordable food and the removal of toxic compounds from soil. These direct and indirect benefits need to be better documented (ICSU, GM Science Review Panel).

Source & ©: FAO "The State of Food and Agriculture 2003-2004"
Chapter 5: Health and environmental impacts of transgenic crops 
Section Food Safety implications, Subsection Potential health benefits of transgenic foods

4.2 How should genetically modified food safety be assessed?

The source document for this Digest states:

BOX 17
The nature of risk and risk analysis
Risk is an integral part of everyday life. No activity is without risk. In some cases inaction also entails risk. Agriculture in any form poses risks to farmers, consumers and the environment. Risk analysis consists of three steps: risk assessment, risk management and risk communication. Risk assessment evaluates and compares the scientific evidence regarding the risks associated with alternative activities. Risk management - which develops strategies to prevent and control risks within acceptable limits - relies on risk assessment and takes into consideration various factors such as social values and economics. Risk communication involves an ongoing dialogue between regulators and the public about risk and options to manage risk so that appropriate decisions can be made.

Risk is often defined as “the probability of harm”. A hazard, by contrast, is anything that might conceivably go wrong. A hazard does not in itself constitute a risk. Thus assessing risk involves answering the following three questions: What might go wrong? How likely is it to happen? What are the consequences? The risk associated with any action depends on all three elements of the equation:

          Risk = hazard x probability x consequences.

The seemingly simple concept of risk assessment is in fact quite complex and relies on judgement in addition to science. Risk can be underestimated if some hazards are not identified and properly characterized, if the probability of the hazard occurring is greater than expected or if its consequences are more severe than expected. The probability associated with a hazard also depends, in part, on the management strategy used to control it.

In daily life, risk means different things to different people, depending on their social, cultural and economic backgrounds. People who are struggling to survive may be willing to accept more risk than people who are comfortably well-off, if they believe it carries a chance of a better life. On the other hand, many poor farmers choose only low-risk technologies because they are functioning at the margins of survival and cannot afford to take chances. Risk also means different things to the same person at different times, depending on the particular issue and the particular situation. People are more likely to accept the risks associated with familiar and freely chosen activities, even if the risks are large. In risk analysis, the following questions should be kept in mind: Who bears the risk and who stands to benefit? Who evaluates the harm? Who decides what risks are acceptable?

Source & ©: FAO "The State of Food and Agriculture 2003-2004"
Chapter 5: Health and environmental impacts of transgenic crops  Box 17

International standards for food safety analysis

At the 26th session of the Codex Alimentarius Commission, held from 30 June to 7 July 2003, landmark agreements were adopted on principles for the evaluation of food derived from modern biotechnology (FAO/WHO, 2003a), and on guidelines for the conduct of food safety assessment of foods derived from recombinant-DNA plants (FAO/WHO, 2003b) and from foods produced using recombinant-DNA micro-organisms (FAO/WHO, 2003c). A fourth document on labelling remains under discussion.

These Codex guidelines indicate that the safety assessment process for a transgenic food should be conducted through comparing it with its traditional counterpart, which is generally considered as safe because of a long history of use, focusing on the determination of similarities and differences. If any safety concern is identified, the risk associated with it should be characterized to determine its relevance to human health. This begins with the description of the host and donor organisms and the characterization of the genetic modification. The subsequent safety assessment should consider factors such as toxicity, tendencies to provoke allergic reaction (allergenicity), effects of changed composition of key nutrients (antinutrients) and metabolites, the stability of the inserted gene and nutritional modification associated with genetic modification. If the entire assessment of these factors concludes that the GM food in question is as safe as its conventional counterpart, the food is then considered safe to eat.

Critics of this comparative approach argue that non-targeted methods that analyse the content of whole foods are needed to assess both intended and unintended effects (ICSU). Scientists generally agree that transgenic foods should be assessed on a case-by-case basis, focusing on the particular product rather than on the process by which it was created. They also agree that the safety of GM foods should be assessed before they are put on the market, because postmarket monitoring is likely to be difficult, expensive and may not yield useful data because of the complex composition of diets and genetic variability in populations (ICSU).

Principles for the risk analysis of foods derived from modern biotechnology

The Principles define modern biotechnology as in the Cartagena Biosafety Protocol, and include principles on risk assessment, risk management and risk communication. The Principles acknowledge that the risk analysis approaches used to assess chemical hazards for substances such as pesticide residues, contaminants, food additives and processing aids are difficult to apply to whole foods. The risk assessment principles clarify that risk assessment includes a safety assessment designed to identify whether a hazard, nutritional or other safety concern is present and, if so, to gather information on its nature and severity. They reflect the concept of substantial equivalence whereby the safety assessment should include, but should not be substituted for, a comparison between the food derived from modern biotechnology and its conventional counterpart. The comparison should determine similarities and differences between the two. A safety assessment should (a) account for intended and unintended effects, (b) identify new or altered hazards and (c) identify changes relevant to human health in key nutrients. Safety assessment should take place on a case-by-case basis.

Risk management measures are to be proportional to the risk. These should take into account, where relevant, “other legitimate measures” according to general decisions of the Codex Commission and the Codex working principles on risk analysis (FAO/WHO, 2003d). Different risk management measures can meet the same objective. Risk managers are to account for the uncertainties identified in the risk assessment and manage the uncertainties. Risk management measures could include food labelling, conditions on marketing approvals, postmarketing monitoring and development of methods to detect or identify foods derived from modern biotechnology. The tracing of the product may also be useful for the smooth operation of the risk management measure.

The risk communication principles are premised on the ideal that effective communication is essential in all phases of risk assessment and management. It is to be an interactive process stimulating advice and stakeholder participation. Processes should be transparent, fully documented and open to public scrutiny while respecting legitimate concerns for confidential commercial information. Safety assessment reports and other aspects of the decision-making process should be available to the public. Responsive consultation processes should be created.

Guideline for the conduct of food safety assessment of foods derived from recombinant-DNA plants

The Guideline for the conduct of food safety assessment of foods derived from recombinant-DNA plants was also adopted by the 26th session (July 2003). The Guideline is designed to support the Principles for the risk analysis of foods derived from modern biotechnology. It describes the recommended approach for making a safety assessment of foods derived from recombinant-DNA plants where a conventional counterpart exists. A conventional counterpart is defined as “a related plant variety, its components and/or products for which there is experience of establishing safety based on a common use as food”. The techniques described in the Guideline may be applied to foods derived from plants that have been altered by techniques other than modern biotechnology.

The Guideline provides an introduction and rationale for food safety assessment of recombinant-DNA plants, drawing distinctions between it and conventional toxicological risk assessment for individual compounds that rely on animal studies. The “goal of the assessment is a conclusion as to whether the new food is as safe as and no less nutritious than the conventional counterpart against which it is compared”. The Guideline indicates that substantial equivalence is not a safety assessment per se. Rather, it represents a starting point to structure food safety assessments relative to a conventional counterpart. Substantial equivalence is used to identify similarities and differences between the new food and the conventional counterpart. The safety assessment then assesses the safety of identified differences, taking into consideration unintended effects resulting from genetic modification. Risk managers subsequently judge this and design risk management measures as appropriate.

Guideline for the conduct of food safety assessment of foods produced using recombinant-DNA micro-organisms

This Guideline is also intended to provide guidance on the safety assessment procedure of foods that are produced by using recombinant-DNA micro-organisms, based on the risk assessment framework of the above-mentioned Principles. The interesting point in the case of recombinant-DNA micro-organisms is that the comparison is recommended not only between the recombinant-DNA micro-organisms and their conventional counterparts (micro-organisms) but also between the foods produced by using them and the original foods.

Source & ©: FAO "The State of Food and Agriculture 2003-2004"
Chapter 5: Health and environmental impacts of transgenic crops 
Section International standards for food safety analysis

4.3 How should genetically modified foods be labelled in the market place?

The source document for this Digest states:

Codex text under discussion on the labelling of genetically modified foods

In addition to the principles and guidelines above, the Draft guidelines for the labelling of foods obtained through certain techniques of genetic modification/genetic engineering (FAO/WHO, 2003e) are still in an early stage of discussion and many sections are bracketed, meaning the language has not yet been agreed. The guideline is proposed to apply to labelling of foods and food ingredients in three situations, when they are: (1) significantly different from conventional counterparts; (2) composed of or contain GM/GE organisms or contain protein or DNA resulting from gene technology; and (3) when they are produced from but do not contain GM/GE organisms, protein or DNA from gene technology.

According to the ICSU, scientists do not fully agree about the appropriate role of labelling. Although mandatory labelling is traditionally used to help consumers identify foods that may contain allergens or other potentially harmful substances, labels are also used to help consumers who wish to select certain foods on the basis of their mode of production, on environmental (e.g. organic), ethical (e.g. fair trade) or religious (e.g. kosher) grounds. Countries differ in the types of labelling information that are mandatory or permitted. According to the ICSU, “labelling of foods as GM or non-GM may enable consumer choice as to the process by which the food is produced [but] it conveys no information as to the content of the foods, and whether there are any risks and/or benefits associated with particular foods.” The ICSU suggests that more informative food labelling that explained the type of transformation and any resulting compositional changes could enable consumers to assess the risks and benefits of particular foods. (Chapter 6 contains a more complete discussion of labelling).

Source & ©: FAO "The State of Food and Agriculture 2003-2004"
Chapter 5: Health and environmental impacts of transgenic crops 
Section International standards for food safety analysis
Subsection Codex text under discussion on the labelling of genetically modified foods

For details on: See FAO report:
Food labeling and biotechnology Chapter 6 , section Section Food labeling and biotechnology 

FacebookTwitterEmail
Themes covered
Publications A-Z
Leaflets