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5. Health and environmental impacts of transgenic crops

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).4 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),5 the United Kingdom GM Science Review Panel (2003 - referred to hereafter as GM Science Review Panel)6 and the Royal Society (2003 - referred to hereafter as Royal Society)7 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.

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.

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?

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).

BOX 18
International standards to facilitate trade

Opportunities for agricultural trade have increased dramatically over the past several years as a result of reforms in international trade under the World Trade Organization (WTO). To a large extent, these reforms centred on reducing tariffs and subsidies in various sectors. The Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement) was also adopted under the WTO in 1994 and entered into force in 1995. The SPS Agreement establishes that countries retain their right to ensure that the food, animal and plant products they import are safe, and at the same time it states that countries should not use unnecessarily stringent measures as disguised barriers to trade.

The SPS Agreement concerns in particular: the protection of animal or plant life or health arising from the entry, establishment or spread of pests, diseases, disease-carrying organisms or disease-causing organisms; the protection of human or animal life or health from risks arising from additives, contaminants, toxins or disease-causing organisms in foods, beverages or feedstuffs; the protection of human life or health from risks arising from diseases carried by animals, plants or products thereof, or from the entry, establishment or spread of pests; and the prevention or limitation of other damage from the entry, establishment or spread of pests.

The SPS Agreement states that countries should use internationally agreed standards in establishing their requirements for sanitary and phytosanitary measures. To meet this objective, three international standard-setting bodies are identified: the Codex Alimentarius Commission for food safety, the International Office of Epizootics (OIE)1 for animal health and the IPPC for plant health. By using standards, countries can reach the level of protection needed to protect human, animal or plant life or health. Countries may also adopt measures that differ from standards, but in these cases, the measures should be technically justified and based on risk assessment.

1 Since renamed the World Organisation for Animal Health, although the acronym OIE has been retained.

BOX 19
Health and environmental concerns in conventional plant breeding

Prior to the advent of genetic engineering, plant breeding was not subject to a great deal of regulation. Seed certification standards ensure the purity and quality of seeds, but little attention has been paid to the possible food safety or environmental impacts of new plant varieties derived from conventional breeding.

Conventional plant breeding differs considerably from natural selection. Natural selection creates resilient biological systems; it ensures the development of an organism that contains properties that adapt it to a variety of environmental conditions and ensure continuation of the species. Artificial selection and conventional plant breeding break down precisely these resilient systems, thereby creating gene combinations that would rarely survive in nature.

Conventional breeding has been responsible for a few cases of negative effects on human health. In one case a potato cultivar was found to contain excessive levels of naturally occurring toxins, and in another case a celery cultivar conventionally bred for high insect resistance caused a skin rash if harvested by hand without protection.

Similarly, the potential impacts of conventionally bred crops on the environment or on farmers' traditional varieties generally have not given rise to regulatory controls, although some of the concerns associated with genetically transformed crops are equally applicable to conventional crops. Most of the world's major food crops are not native to their major production zones; rather, they originated in a few distinct “centres of origin” and were transferred to new production areas through migration and trade. Highly domesticated plants are grown all over the world and migration outside cultivated areas has only rarely caused a serious problem. Even when grown in their centre of origin, as with potatoes in South America or maize in Mexico, hybrids between cultivated and wild species have not been permanently established. There are several reports of gene flow between cultivated plants and their wild relatives but in general this has not been considered a problem.

Source: DANIDA, 2002.

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).

BOX 20
“Clean gene” transformation at CIMMYT

Alessandro Pellegrineschi and David Hoisington1

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.

1 The authors are, respectively, Cell Biologist and Director of the Applied Biotechnology Center of CIMMYT in Mexico.

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).

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).

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.

BOX 21
Genetically modified crops as animal feed

Genetically modified crops, products derived from them and enzymes derived from genetically modified micro-organisms are widely used in animal feeds. The global animal feed market is estimated at some 600 million tonnes. Compound feeds are principally used for poultry, pigs and dairy cows and are formulated from a range of raw materials, including maize and other cereals and oilseeds such as soybeans and canola. It is currently estimated that 51 percent of the global area of soybeans, as well as 12 percent of canola and 9 percent of maize (used as whole maize and by-products such as maize gluten feed) is genetically modified (James, 2002a).

Safety assessments of novel livestock feeds in Canada, the United States and elsewhere look at the molecular, compositional, toxicological and nutritional characteristics of the novel feed compared with its conventional counterpart. Considerations include the effects on the animal eating the feed and on consumers eating the resulting animal product, worker safety and other environmental aspects of using the feed. In addition, comparisons of nutritional composition and wholesomeness between animal feeds containing transgenic versus conventional components have been the subject of many studies.

The major concerns associated with the use of GM products in animal feeds are whether modified DNA from the plant may be transferred into the food chain with harmful consequences and whether antibiotic-resistance marker genes used in the transformation process may be transferred to bacteria in the animal and hence potentially into human pathogenic bacteria. As the production process for the enzymes used in animal feeds takes place under controlled conditions in closed fermentation tank installations and eliminates the modified DNA from the final products, these products do not pose any risk to the animal or the environment. The enzyme phytase has particular benefits in feeding pigs and poultry, including a significant reduction in the amount of phosphorus released to the environment.

Researchers have examined the effects of feed processing on DNA to ascertain whether modified DNA remains intact and moves into the food chain. It has been found that DNA is not fragmented to any great extent in raw plant material and silage, but remains partially or fully intact. This means that, if GM crops are fed to animals, animals would be likely to be eating modified DNA. In order to consider whether modified DNA or derived proteins consumed by animals have the potential to affect animal health or to enter the food chain, it is necessary to consider the fate of these molecules within the animal. Digestion of nucleic acids (DNA and ribonucleic acid, RNA) occurs through the action of nucleases present in the mouth, the pancreas and intestinal secretions. In ruminants, additional microbial and physical degradation of feed occurs. Evidence suggests that more than 95 percent of DNA and RNA is completely broken down within the digestive system. In addition, research carried out on the digestion of transgenic proteins in in vitro culture has shown nearly complete digestion occurring within five minutes in the presence of the enzyme pepsin.

Of further concern is whether there can be transfer of antibiotic resistance from the marker genes used in the production of GM plants to micro-organisms in animals and thence to bacteria pathogenic to humans. A review commissioned by FAO has concluded that this is extremely unlikely to happen (Chambers and Heritage, 2004). Nevertheless, this paper concluded that markers which code for resistance to clinically significant antibiotics, critical for treating human infectious diseases, should not be used in the production of transgenic plants.

MacKenzie and McLean (2002) reviewed 15 feeding studies of dairy cattle, beef cattle, swine and chickens published between 1995 and 2001. The feeds studied were insect- and/or herbicide-resistant maize and soybeans. The animals were fed a transgenic or conventional product for time periods ranging from 35 days for poultry to two years for beef cattle. None of these studies found any adverse effects in the animals fed the transgenic products for any of the measured parameters, which included nutrient composition, body weight, feed intake, feed conversion, milk production, milk composition, rumen fermentation, growth performance or carcass characteristics. Two of the studies found slight improvements in feed conversion rates for the animals fed insect-resistant maize, possibly because of lower concentrations of aflatoxins, antinutrients that result from insect damage.

In summary, it may be concluded that the risks to human and animal health from the use of GM crops and enzymes derived from genetically modified micro-organisms as animal feed are negligible. Nevertheless, some countries do require labelling to indicate the presence of GM material in imports and products derived thereof.

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.)

Environmental implications

Agriculture of any type - subsistence, organic or intensive - affects the environment, so it is natural to expect that the use of new genetic techniques in agriculture will also affect the environment. The ICSU, the GM Science Review Panel and the Nuffield Council on Bioethics, among others, agree that the environmental impact of genetically transformed crops may be either positive or negative depending on how and where they are used. Genetic engineering may accelerate the damaging effects of agriculture or contribute to more sustainable agricultural practices and the conservation of natural resources, including biodiversity. The environmental concerns associated with transgenic crops are summarized below along with the current state of scientific knowledge regarding them.

Releasing transgenic crops into the environment may have direct effects including: gene transfer to wild relatives or conventional crops, weediness, trait effects on non-target species and other unintended effects. These risks are similar for transgenic and conventionally bred crops (ICSU). Although scientists differ in their views on these risks, they agree that environmental impacts need to be assessed on a case-by-case basis and recommend post-release ecological monitoring to detect any unexpected events (ICSU, Nuffield Council, GM Science Review Panel). Transgenic crops may also entail positive or negative indirect environmental effects through changes in agricultural practices such as pesticide and herbicide use and cropping patterns.

Transgenic trees involve similar environmental concerns, although there are additional concerns because of their long life cycle. Transgenic micro-organisms used in food processing are normally used under confined conditions and are generally not considered to pose environmental risks. Some micro-organisms can be used in the environment as biological control agents or for bioremediation of environmental damage (e.g. oil spills), and their environmental effects should be assessed prior to release. Environmental concerns related to transgenic fish primarily focus on their potential to breed with and outcompete wild relatives (ICSU). Transgenic farm animals would probably be used in highly confined conditions, so they would pose little risk of environmental damage (NRC, 2002) (Box 22).

BOX 22
Environmental concerns regarding genetically modified animals

No GM animals are currently being used in commercial agriculture anywhere in the world (Chapter 2), but several livestock and aquatic species are under research for a variety of transgenic traits. Studies of the potential environmental concerns associated with GM animals have been conducted recently by the United States National Research Council (NRC, 2002), the United Kingdom Agriculture and Environment Biotechnology Commission (AEBC, 2002) and the Pew Initiative on Food and Biotechnology (Pew Initiative, 2003). These studies conclude that GM animals may have either positive or negative effects on the environment depending on the particular animal, trait and production environment in which it is introduced. The main environmental concerns associated with animals involve: (a) the possibility that transgenic animals could escape with resultant negative effects on wild relatives or ecosystems, and (b) potential changes in production practices that may lead to varying degrees of environmental stress. These reports recommend that GM animals should be evaluated in relation to their conventional counterparts.

The three studies agree that transgenic animals should be evaluated for their ability to escape and become established in different environments. The NRC and AEBC agree that adverse environmental impacts are less likely for livestock breeds than for fish, because most farm animal species have no wild relatives remaining and farm animal reproduction is confined to managed herds and flocks. The danger of becoming feral is low in cattle, sheep and domestic chickens, which are less mobile and highly domesticated, but higher in horses, camels, rabbits, dogs and laboratory animals (rats and mice). Non-transgenic domestic goats, pigs and cats have been known to become feral, causing extensive damage to ecological communities (NRC, 2002). Transgenic farm animals would be particularly valuable and therefore would be kept in carefully controlled environments. Aquacultured fish, by contrast, are naturally mobile and breed easily with wild species. The AEBC report recommends that transgenic fish should not be raised in offshore pens owing to the high probability of escape. The Pew Initiative study points out that the impact of escaped aquaculture fish, whether transgenic or conventionally bred, depends on their “net fitness” compared with wild species. It argues that transgenic traits could increase or decrease the net fitness of farmed species, and recommends that transgenic fish be carefully evaluated and regulated in an integrated and transparent way.

Transgenic animals could also lead to environmental impacts through changes in the animals themselves or in the management practices associated with them. Transgenic modifications could reduce the amount of manure and methane emissions produced by livestock and aquaculture species (AEBC, 2002; Pew Initiative, 2003) or increase their resistance to diseases (promoting lower antibiotic usage). On the other hand, some genetic modifications could lead to more intensive livestock production with associated increases in environmental pollutants. The question of environmental harm is therefore less a question of the technology itself than of the capacity to manage it.

An additional factor to consider with livestock biotechnology is the possible effects on the welfare of animals. These welfare effects may be positive or negative and should be evaluated against conventional livestock management practices (AEBC, 2002). At present, the production of transgenic and cloned animals is extremely inefficient, with high mortality during early embryonic development and success rates of only 1-3 percent. Of the transgenic animals born, the inserted genes may not function as expected, often resulting in anatomical, physiological and behavioural abnormalities (NRC, 2002). Cattle produced by cloning methods tend to have longer gestation periods and higher birth weights, resulting in a higher rate of Caesarean births (NRC, 2002; AEBC, 2002). Such problems can also occur with animals produced using AI/MOET, and should be evaluated in the context of the other reproductive technologies used in livestock production (AEBC, 2002). The AEBC report further recommends that the potential welfare effects of all technologies used in animal agriculture should be weighed against economic and environmental considerations.

Gene flow

Scientists agree that gene flow from GM crops is possible through pollen from open-pollinated varieties crossing with local crops or wild relatives. Because gene flow has happened for millennia between land races and conventionally bred crops, it is reasonable to expect that it could also happen with transgenic crops. Crops vary in their tendency to outcross, and the ability of a crop to outcross depends on the presence of sexually compatible wild relatives or crops, which varies according to location (Box 23 on page 70) (ICSU, GM Science Review Panel).

Scientists do not fully agree whether or not gene flow between transgenic crops and wild relatives matters, in and of itself (ICSU, GM Science Review Panel). If a resulting transgenic/wild hybrid had some competitive advantage over the wild population it could persist in the environment and potentially disrupt the ecosystem. According to the GM Science Review Panel, hybridization between transgenic crops and wild relatives seems “overwhelmingly likely to transfer genes that are advantageous in agricultural environments, but will not prosper in the wild … Furthermore, no hybrid between any crop and any wild relative has ever become invasive in the wild in the UK” (GM Science Review Panel, 2003: 19).

Whether the otherwise benign flow of transgenes into land races or other conventional varieties would itself constitute an environmental problem is a matter of debate, because conventional crops have long interacted with land races in this way (ICSU). Research is needed to improve the assessment of the environmental consequences of gene flow, particularly in the long run, and to understand better the gene flow between the major food crops and land races in centres of diversity (ICSU, GM Science Review Panel).

Weediness refers to the situation in which a cultivated plant or its hybrid becomes established as a weed in other fields or as an invasive species in other habitats. Scientists agree that there is only a very low risk of domesticated crops becoming weeds themselves because the traits that make them desirable as crops often make them less fit to survive and reproduce in the wild (ICSU, GM Science Review Panel). Weeds that hybridize with herbicide-resistant crops have the potential to acquire the herbicide-tolerant trait, although this would only provide an advantage in the presence of the herbicide (ICSU, GM Science Review Panel). According to the GM Science Review Panel, “Detailed field experiments on several GM crops in a range of environments have demonstrated that the transgenic traits investigated - herbicide tolerance and insect resistance - do not significantly increase the fitness of the plants in semi-natural habitats” (GM Science Review Panel, 2003:19). Some transgenic traits, such as pest or disease resistance, could provide a fitness advantage but there is little evidence so far that this happens or has any negative environmental consequences (ICSU, GM Science Review Panel). More evidence is required regarding the effect of fitness-enhancing traits on invasiveness (GM Science Review Panel).

Management and genetic methods are being developed to minimize the possibility of gene flow. The complete isolation of crops grown on a commercial scale, either GM or non-GM, is not currently practical although gene flow can be minimized, as it currently is between oilseed rape varieties grown for food, feed or industrial oils (GM Science Review Panel). Management strategies include avoiding the planting of transgenic crops in their centres of biodiversity or where wild relatives are present, or using buffer zones to isolate transgenic varieties from conventional or organic varieties. Genetic engineering can be used to alter flowering periods to prevent cross-pollination or to ensure that the transgenes are not incorporated in pollen and developing sterile transgenic varieties (ICSU and Nuffield Council). The GM Science Review Panel and other expert bodies recommend that GM crops that produce medical or industrial substances should be designed and grown in ways that would avoid gene flow to food and feed crops (GM Science Review Panel).

BOX 23
An ecologist's view of gene flow from transgenic crops

Allison A. Snow1

Most ecological scientists agree that gene flow is not an environmental problem unless it leads to undesirable consequences. In the short term, the spread of transgenic herbicide resistance via gene flow may create logistical and/or economic problems for growers. Over the long term, transgenes that confer resistance to pests and environmental stress and/or lead to greater seed production have the greatest likelihood of aiding weeds or harming non-target species. However, these outcomes seem unlikely for most currently grown transgenic crops. Many transgenic traits are likely to be innocuous from an environmental standpoint, and some could lead to more sustainable agricultural practices. To document various risks and benefits, there is a great need for academic researchers and others to become more involved in studying transgenic crops. Similarly, it is crucial that molecular biologists, crop breeders and industry improve their understanding of ecological and evolutionary questions about the safety of new generations of transgenic crops.

The presence of wild and weedy relatives varies among countries and regions. The chart shows examples of major crops grouped by their ability to disperse pollen and the occurrence of weedy relatives in the continental United States. This simple 2 x 2 matrix can be useful in identifying cases where gene flow from a transgenic crop to a wild relative is likely. For crops where no wild or weedy relatives are grown nearby - as with soybean, cotton and maize shown here in green - gene flow to the wild would not occur. Rice, sorghum and wheat have wild relatives in the United States and a relatively low tendency to outcross, which could allow transgenes to disperse into wild populations. The crops that have a high tendency to outcross and have wild relatives in the United States are shown in red. There is a high potential for gene flow between these crops and their wild relatives, so care should be taken in growing transgenic varieties that might confer a competitive advantage on their hybrids.

1 Dr Snow is a Professor in the Department of Evolution, Ecology, and Organismal Biology at The Ohio State University, United States.

Trait effects on non-target species

Some transgenic traits - such as the pesticidal toxins expressed by Bt genes - may affect non-target species as well as the crop pests they are intended to control (ICSU). Scientists agree that this could happen but they disagree about how likely it is (ICSU, GM Science Review Panel). The monarch butterfly controversy (Box 24 on page 71) demonstrated that it is difficult to extrapolate from laboratory studies to field conditions. Field studies have shown some differences in soil microbial community structure between Bt and non-Bt crops, but these are within the normal range of variation found between cultivars of the same crop and do not provide convincing evidence that Bt crops could be damaging to soil health in the long term (GM Science Review Panel). Although no significant adverse effects on non-target wildlife or soil health have so far been observed in the field, scientists disagree regarding how much evidence is needed to demonstrate that growing Bt crops is sustainable in the long term (GM Science Review Panel). Scientists agree that the possible impacts on non-target species should be monitored and compared with the effects of other current agricultural practices such as chemical pesticide use (GM Science Review Panel). They acknowledge that they need to develop better methods for field ecological studies, including better baseline data with which to compare new crops (ICSU).

BOX 24
Does Bt maize kill monarch butterflies?

John Losey, an entomologist at Cornell University, published a research paper in the scientific journal Nature that seemed to prove that pollen from Bt maize killed monarch butterflies (Losey, Rayor and Carter, 1999). Losey and his colleagues found that when they spread the pollen from a commercial variety of Bt maize on milkweed leaves in the laboratory and fed them to monarch butterfly caterpillars, the caterpillars died.

Six independent teams of researchers conducted follow-up studies on the effects of Bt maize pollen on monarch butterfly caterpillars, published in 2001 in the Proceedings of the National Academy of Sciences of the United States of America. Although these studies agreed that the pollen used in the original study was toxic at high doses, they found that Bt maize pollen posed negligible risk to monarch larvae under field conditions. They based their conclusion on four facts: (a) the Bt toxin is expressed at fairly low levels in the pollen of most commercial Bt maize varieties, (b) maize and milkweed (the normal food of monarch butterfly caterpillars) are generally not found together in the field, (c) there is limited overlap in the time periods when maize pollen sheds in the field and monarch larvae are active and (d) the amount of pollen likely to be consumed under field conditions was not toxic. These studies concluded that the risk of harm to monarch butterfly caterpillars from Bt maize pollen is very small, particularly in comparison with other threats such as conventional pesticides and drought (Conner, Glare and Nap, 2003).

Many scientists are frustrated by the way the monarch butterfly controversy and other issues related to biotechnology were handled in the press. Although the original monarch butterfly study received worldwide media attention, the follow-up studies that refuted it did not receive the same amount of coverage. As a result, many people are not aware that Bt maize poses very little risk to monarch butterflies (Pew Initiative, 2002a).

Indirect environmental effects

Transgenic crops may have indirect environmental effects as a result of changing agricultural or environmental practices associated with the new varieties. These indirect effects may be beneficial or harmful depending on the nature of the changes involved (ICSU, GM Science Review Panel). Scientists agree that the use of conventional agricultural pesticides and herbicides has damaged habitats for farmland birds, wild plants and insects and has seriously reduced their numbers (ICSU, GM Science Review Panel, Royal Society). Transgenic crops are changing chemical and land-use patterns and farming practices, but scientists do not fully agree whether the net effect of these changes will be positive or negative for the environment (ICSU). Scientists acknowledge that more comparative analysis of new technologies and current farming practices is needed.

Pesticide use

The scientific consensus is that the use of transgenic insect-resistant Bt crops is reducing the volume and frequency of insecticide use on maize, cotton and soybean (ICSU). These results have been especially significant for cotton in Australia, China, Mexico, South Africa and the United States (Chapter 4). The environmental benefits include less contamination of water supplies and less damage to non-target insects (ICSU). Reduced pesticide use suggests that Bt crops would be generally beneficial to in-crop biodiversity in comparison with conventional crops that receive regular, broad-spectrum pesticide applications, although these benefits would be reduced if supplemental insecticide applications were required (GM Science Review Panel). As a result of less chemical pesticide spraying on cotton, demonstrable health benefits for farm workers have been documented in China (Pray et al., 2002) and South Africa (Bennett, Morse and Ismael, 2003).

Herbicide use

Herbicide use is changing as a result of the rapid adoption of HT crops (ICSU). There has been a marked shift away from more toxic herbicides to less toxic forms, but total herbicide use has increased (Traxler, 2004). Scientists agree that HT crops are encouraging the adoption of low-till crops with resulting benefits for soil conservation (ICSU). There may be potential benefits for biodiversity if changes in herbicide use allow weeds to emerge and remain longer in farmers' fields, thereby providing habitats for farmland birds and other species, although these benefits are speculative and have not been strongly supported by field trials to date (GM Science Review Panel). There is concern, however, that greater use of herbicides - even less toxic herbicides - will further erode habitats for farmland birds and other species (ICSU). The Royal Society has published the results of extensive farm-scale evaluations of the impacts of transgenic HT maize, spring oilseed rape (canola) and sugar beet on biodiversity in the United Kingdom. These studies found that the main effect of these crops compared with conventional cropping practices was on weed vegetation, with consequent effects on the herbivores, pollinators and other populations that feed on it. These groups were negatively affected in the case of transgenic HT sugar beet, positively affected in the case of maize and showed no effect in spring oilseed rape. They conclude that commercialization of these crops would have a range of impacts on farmland biodiversity, depending on the relative efficacy of transgenic and conventional herbicide regimes and the degree of buffering provided by surrounding fields (Royal Society, 2003:1912). Scientists acknowledge that there is insufficient evidence to predict what the long-term impacts of transgenic HT crops will be on weed populations and associated in-crop biodiversity (GM Science Review Panel).

Pest and weed resistance

Scientists agree that extensive long-term use of Bt crops and glyphosate and gluphosinate, the herbicides associated with HT crops, can promote the development of resistant insect pests and weeds (ICSU, GM Science Review Panel). Similar breakdowns have routinely occurred with conventional crops and pesticides and, although the protection conferred by Bt genes appears to be particularly robust, there is no reason to assume that resistant pests will not develop (GM Science Review Panel). Worldwide, over 120 species of weeds have developed resistance to the dominant herbicides used with HT crops, although the resistance is not necessarily associated with transgenic varieties (ICSU, GM Science Review Panel). Because the development of resistant pests and weeds can be expected if Bt and glyphosate and gluphosinate are overused, scientists advise that a resistance management strategy be used when transgenic crops are planted (ICSU). Scientists disagree about how effectively resistance management strategies can be employed, particularly in developing countries (ICSU). The extent and possible severity of impacts of resistant pests or weeds on the environment are subject to debate (GM Science Review Panel).

Abiotic stress tolerance

As we saw in Chapter 2, new transgenic crops with tolerance to various abiotic stresses (e.g. salt, drought, aluminium) are being developed that may allow farmers to cultivate soils that were previously not arable. Scientists agree that these crops may be environmentally beneficial or harmful depending on the particular crop, trait and environment (ICSU).

Environmental impact assessment

There is broad consensus that the environmental impacts of transgenic crops and other living modified organisms (e.g. transgenic seeds) should be evaluated using science-based risk assessment procedures on a case-by-case basis depending on the particular species, trait and agro-ecosystem. Scientists also agree that the environmental release of transgenic organisms should be compared with other agricultural practices and technology options (ICSU and Nuffield Council).

As we saw above, food safety assessment procedures are well developed and the FAO/WHO Codex Alimentarius Commission provides an international forum for developing food safety guidelines for transgenic foods. By contrast, there are no internationally agreed guidelines and standards for assessing the environmental impacts of transgenic organisms (ICSU). Scientists agree that there is a need for internationally and regionally harmonized methodologies and standards for assessing environmental impacts in different ecosystems (ICSU; FAO, 2004). The role of international standard-setting bodies in providing guidance for risk analysis is described below.

According to the ICSU, regulators in different countries typically require similar types of data for environmental impact assessments, but they differ in their interpretation of these data and of what constitutes an environmental risk or harm. Scientists also differ on what the appropriate basis for comparison should be: with current agricultural systems and/or baseline ecological data (ICSU). An FAO expert consultation (2004) agreed that the impacts of agriculture on the environment were much greater than the measurable impacts of a shift from conventional to transgenic crops, so the basis of comparison is important.

Scientists also disagree about the value of small-scale laboratory and field trials and their extrapolation to large-scale effects, and it is unclear whether modelling approaches that incorporate data from geographical information systems would be useful in predicting the effects of living modified organisms (LMOs) in different ecosystems (ICSU). The scientific community recommends that more research is needed on the post-release effects of transgenic crops. There is also a need for more targeted post-release monitoring and better methodologies for monitoring (ICSU; FAO, 2004).

International environmental agreements and institutions

Several international agreements and institutions are relevant to the environmental aspects of certain transgenic products, among them the Convention on Biological Diversity, the Cartagena Protocol on Biosafety and the International Plant Protection Convention. The roles and provisions of these bodies are described below.

The Convention on Biological Diversity and the Cartagena Protocol on Biosafety

Most of the measures of the Convention on Biological Diversity (CBD) (Secretariat of the Convention on Biological Diversity, 1992) focus on the conservation of ecosystems; however, two aspects concerning the conservation of biological diversity are relevant for biosafety - the management of risks associated with LMOs resulting from biotechnology and the management of risks associated with alien species.

In the context of in-situ conservation measures, the Convention requires contracting parties “… to regulate, manage or control the risks associated with the use and release of living modified organisms resulting from biotechnology which are likely to have adverse environmental impacts that could affect the conservation and sustainable use of biological diversity …”. This provision goes beyond the general scope of the Convention in that it requires also that risks to human health are taken into account.

The Convention establishes that contracting parties have the obligation to prevent the introduction of alien species and to control or to eradicate those alien species that threaten ecosystems, habitats or species. Invasive alien species are considered as species introduced deliberately or unintentionally outside their natural habitats where they have the ability to establish themselves, invade, replace natives and take over the new environment.

The Cartagena Protocol on Biosafety (Secretariat of the Convention on Biological Diversity, 2000) was adopted by the CBD in September 2000 and came into force in September 2003. The objective of the Protocol is to protect biological diversity from the potential risks posed by safe transfer, handling and use of LMOs resulting from modern biotechnology. Risks to human health are also considered. The Protocol is applicable to all LMOs, except pharmaceuticals for humans that are addressed by other international agreements or organizations.

The Protocol sets out an Advance Informed Agreement (AIA) procedure for LMOs intended for intentional introduction into the environment that may have adverse effects on the conservation and sustainable use of biodiversity. The procedure requires, prior to the first intentional introduction into the environment of an importing party:

Four categories of LMO are exempted from the AIA: LMOs in transit, LMOs for contained use, LMOs identified in a decision of the Conference of Parties/Meeting of Parties as not likely to have adverse effects on biodiversity conservation and sustainable use, and LMOs intended for direct use as food, feed or for processing.

For LMOs that may be subject to transboundary movement for direct use as food or feed, or for processing, Article 11 provides that a party that makes a final decision for domestic use, including placing on the market, must notify the Biosafety Clearing-House established under the Protocol. The notification is to contain minimum information required under Annex II. A contracting party may take an import decision under its domestic regulatory framework, provided this is consistent with the Protocol. A developing country contracting party, or a party with a transition economy that lacks a domestic regulatory framework, can declare through the Biosafety Clearing-House that its decision on the first import of an LMO for direct use as food, feed or for processing will be pursuant to a risk assessment. In both cases lack of scientific certainty because of insufficient relevant scientific information and knowledge regarding the extent of potential adverse effects shall not prevent the contracting party of import from taking a decision, as appropriate, in order to avoid or minimize potential adverse effects.

Risk assessment and risk management are requirements for both AIA and Article 11 cases. The risk assessment must be consistent with criteria enumerated in an annex. In principle, risk assessment is to be carried out by competent national decision-making authorities. The exporter may be required to undertake the assessment. The importing party may require the notifier to pay for the risk assessment.

The Protocol specifies general risk management measures and criteria. Any measures based on risk assessment should be proportionate to the risks identified. Measures to minimize the likelihood of unintentional transboundary movement of LMOs are to be taken. Affected or potentially affected states are to be notified when an occurrence may lead to an unintentional transboundary movement.

The Protocol also contains provisions on LMO handling, packaging and transportation (Article 18). In particular, each contracting party is to take measures to require documentation that:

  1. for LMOs intended for direct use as food or feed, or for processing, clearly identifies that they “may contain” LMOs and are “not intended for intentional introduction into the environment”, and a contact point for further information;
  2. for LMOs destined for contained use, clearly identifies them as LMOs and specifies any requirements for safe handling, storage, transport and use, and a contact point and consignee;
  3. for LMOs intended for intentional introduction into the environment of the party of import, clearly identifies them as LMOs and specifies the identity and traits/characteristics, any requirements for safe handling, storage, transport and use, and a contact point, the name/address of the importer/exporter and a declaration that the movement conforms to the Protocol's requirements applicable to the exporter.

Information exchange is envisaged in the Protocol through the establishment of the Biosafety Clearing-House. The Biosafety Clearing-House is intended to facilitate the exchange of information on, and experience with, LMOs and to assist parties in implementation of the Protocol. Pursuant to Article 20, paragraph 2, it shall also provide access to other international biosafety information exchange systems. Information that parties are required to provide to the Clearing-House includes existing laws, regulations and guidelines for implementation of the Protocol; information required for the AIA; any bilateral, regional and multilateral agreements within the context of the Protocol; summaries of risk assessment and final decisions.

Public participation is specifically addressed in Article 23. Contracting parties shall:

  1. promote and facilitate public awareness, education and participation concerning safe transfer, handling and use of LMOs;
  2. endeavour to ensure public awareness and education encompasses access to information on LMOs identified by the Protocol that may be imported;
  3. consult the public in the decision-making process regarding LMOs and shall make decisions available to the public in accordance with national laws and regulations. Confidential information is to be respected in those activities.

Socio-economic considerations are allowed in decision-making. Contracting parties may account for socio-economic considerations arising from the impact of LMOs on biodiversity conservation and sustainable use, especially with regard to the value of biodiversity to indigenous and local communities. The parties are encouraged to cooperate on research and information exchange on any socio-economic impacts of LMOs. A process to address liability and redress for damage resulting from LMO transboundary movements is to be set up by the first meeting of parties to the Protocol.

The IPPC and living modified organisms

The purpose of the International Plant Protection Convention (IPPC) is to secure common and effective action to prevent the spread and introduction of pests of plants and plant products, and to promote measures for their control. Although the IPPC makes provision for trade in plants and plant products, it is not limited in this respect. Specifically, the scope of the IPPC extends to the protection of wild flora in addition to cultivated flora, and covers both direct and indirect damage from pests, including weeds. The IPPC plays an important role in the conservation of plant biodiversity and in the protection of natural resources. Hence, standards developed under the IPPC are also applicable to key elements of the CBD, including the prevention and mitigation of impacts of alien invasive species, and the Cartagena Protocol on Biosafety. As a consequence, the CBD, FAO and IPPC have established a close collaborative relationship. This has in particular extended to the inclusion of CBD concerns in the development of new international standards for phytosanitary measures (ISPMs).

ISPMs developed under the auspices of the IPPC provide internationally agreed guidance to countries on measures to protect plant life or health from the introduction and spread of pests or diseases. One of the most important concept standards developed under the IPPC is ISPM No. 11, Pest risk analysis for quarantine pests (FAO, 2001b), adopted by the Interim Commission on Phytosanitary Measures (ICPM) at its 3rd Session in 2001. In addition, the ICPM, at its 5th Session in 2003, adopted a supplement to ISPM No. 11 to address risks to the environment in order to take into account CBD concerns, especially with regard to invasive alien species. More recently, the IPPC has drafted another supplement to ISPM No. 11 to address pest risk analysis for LMOs.8

This draft standard has undergone extensive technical discussion and consultation throughout its development. At the request of the ICPM, an open-ended expert working group was convened in September 2001 and included government-nominated experts from developed and developing countries and experts representing both plant protection and environmental concerns. The purpose of the meeting was to discuss the development of this standard and the need to provide detailed guidance on conducting risk analyses to address the potential plant health effects of LMOs with particular attention to the needs of developing countries.

The working group considered that potential phytosanitary risks of LMOs that may need to be considered in a pest risk analysis include (FAO, 2002b):

Subsequently, a small working group, including CBD/Cartagena Protocol and plant protection experts, met to prepare a draft standard that would provide general guidelines on the conduct of pest risk analysis with respect to the potential phytosanitary risks identified above. In the process of drafting the standard, the working group noted several important issues with regard to the scope of the IPPC and potential phytosanitary risks of LMOs. In particular, the working group noted that whereas some types of LMO would require pest risk analyses because they could present phytosanitary risks, many other categories of LMO, e.g. those with modified characteristics such as ripening time or storage/shelf life, do not present phytosanitary risks. Similarly, it was noted that pest risk analysis would only address the phytosanitary risks of LMOs, but that other potential risks may also need to be addressed (e.g. human health concerns for food products). It was also noted that the potential phytosanitary risks identified above could also be associated with non-LMOs, or conventionally bred crops. It was acknowledged that risk analysis procedures of the IPPC are generally concerned with phenotypic characteristics rather than genotypic characteristics and it was noted that the latter may need to be considered when assessing the phytosanitary risks of LMOs.

At the time of the publication of this document, the draft standard has been reviewed by the Standards Committee and been distributed to all members for review and comment. Comments on the draft standard received from countries were reviewed by the Standards Committee in November 2003. The draft standard will be modified taking into account received comments, and should be submitted to the ICPM at its 6th Session in April 2004 for its approval.


Thus far, in those countries where transgenic crops have been grown, there have been no verifiable reports of them causing any significant health or environmental harm. Monarch butterflies have not been exterminated. Pests have not developed resistance to Bt. Some evidence of HT weeds has emerged, but superweeds have not invaded agricultural or natural ecosystems. On the contrary, some important environmental and social benefits are emerging. Farmers are using less pesticide and are replacing toxic chemicals with less harmful ones. As a result, farm workers and water supplies are protected from poisons, and beneficial insects and birds are returning to farmers' fields.

Meanwhile, science is moving ahead rapidly. Some of the concerns associated with the first generation of transgenic crops have technical solutions. New techniques of genetic transformation are eliminating the antibiotic marker genes and promoter genes that are of concern to some. Varieties including two different Bt genes are reducing the likelihood that pest resistance will develop. Management strategies and genetic techniques are evolving to prevent gene flow.

However, the lack of observed negative effects so far does not mean they cannot occur, and scientists agree that our understanding of ecological and food safety processes is incomplete. Much remains unknown. Complete safety can never be assured, and regulatory systems and the people who manage them are not perfect. How should we proceed given the lack of scientific certainty? The GM Science Review Panel (p. 25) argues that:

There is a clear need for the science community to do more research in a number of areas, for companies to make good choices in terms of transgene design and plant hosts, and to develop products that meet wider societal wishes. Finally, the regulatory system … should continue to operate so that it is sensitive to the degree of risk and uncertainty, recognises the distinctive features of GM, divergent scientific perspectives and associated gaps in knowledge, as well as taking into account the conventional breeding context and baselines.

The Nuffield Council (p. 44) recommends that “the same standards should be applied to the assessment of risks from GM and from non-GM plants and foods, and that the risks of inaction be given the same careful analysis as risks of action …” They further conclude (p. 45):

We do not take the view that there is enough evidence of actual or potential harm to justify a moratorium on either research, field trials, or the controlled release of GM crops into the environment at this stage. We therefore recommend that research into GM crops be sustained, governed by a reasonable application of the precautionary principle.

FAO's Statement on biotechnology (FAO, 2000b) concurs:

FAO supports a science-based evaluation system that would objectively determine the benefits and risks of each individual GMO. This calls for a cautious case-by-case approach to address legitimate concerns for the biosafety of each product or process prior to its release. The possible effects on biodiversity, the environment and food safety need to be evaluated, and the extent to which the benefits of the product or process outweigh its risks assessed. The evaluation process should also take into consideration experience gained by national regulatory authorities in clearing such products. Careful monitoring of the post-release effects of these products and processes is also essential to ensure their continued safety to human beings, animals and the environment.

Science cannot declare any technology completely risk free. Genetically engineered crops can reduce some environmental risks associated with conventional agriculture, but will also introduce new challenges that must be addressed. Society will have to decide when and where genetic engineering is safe enough.

4 The International Council for Science (ICSU) is a non-governmental organization representing the international scientific community. The membership includes both national science academies (101 members) and international scientific unions (27 members). Because the ICSU is in contact with hundreds of thousands of scientists worldwide, it is often called upon to represent the world scientific community. '
5 The Nuffield Council on Bioethics is a British non-profit organization funded by the Medical Research Council, the Nuffield Foundation and the Wellcome Trust.
6 The GM Science Review Panel is a group established by the United Kingdom Government to conduct a thorough, impartial review of the scientific evidence regarding GM crops.
7 The Royal Society is the independent scientific academy of the United Kingdom, dedicated to promoting excellence in science.
8 The Cartagena Protocol on Biosafety defines a living modified organism (LMO) as “any living organism that possesses a novel combination of genetic material obtained through the use of modern biotechnology” (Secretariat of the Convention on Biological Diversity, 2000: 4).

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