The world’s population has increased from 2.5 billion to 6.3 billion in the last 50 years and the population explosion threatens that another 3 billion people will inhabit the planet by 2100. Each night 800 million people go to bed hungry and about 842 million people suffer from malnutrition. It could be very difficult to improve nutritional deficiency exclusively by traditional breeding and better management of crops. Efforts are being made towards nutritional improvement of crops by using the tools of biotechnology by increasing the levels of essential nutrients .Adoption of biotechnology in agriculture has been the focus of controversy due to varied reasons, as questions have arisen regarding food and environmental safety. The food safety assessment requires the evaluation of safety of newly added DNA and the safety of their gene products and overall safety of balance of food. The concept of substantial equivalence has been accepted as the cornerstone of the health hazard assessment of genetically modified (GM) foods. The main safety issues for new varieties of crops include potential toxicity of the newly introduced protein(s), potential changes in allergencity, changes in nutrient composition, unintended effects giving rise to allergencity and toxicity besides the safety of antibiotic resistance marker encoded proteins associated with the transgene. Therefore evaluation of such interventions necessitates establishing “the reasonable likelihood of safety” and that new varieties are as safe as or safer than the crops produced through traditional methods.
The United Nations (UN) charter declared that freedom from hunger is a fundamental human right. Diets that are deficient in essential nutrients can be a pervasive cause of hunger and undernutrition. The UN millenium project recognized that the number of undernourished people in the world has fallen from approximately 1.5 billion in early 1970’s to around 850 million in 1990s and targeted to reduce this number by half by 2015. However it is sobering to note that even the achievement of this goal will leave the world with more than 400 million undernourished humans.
Insufficient food intake results in many forms of macro and micronutrient undernutrition. Micronutrient deficiencies are widespread in developing countries, especially in Asia and Africa. The World Health Organization (WHO) has recognized that such nutrient deficiencies have catastrophic effects on health and quality of life of at least 2 billion people. Deficiencies in micronutrients such as iron, Vitamin A, Iodine, Zinc, and Folic acid affect large numbers of people, especially children resulting in significant morbidity and mortality. In many situations, deficiencies in energy and multiple nutrients occur, and these are thought to exert synergistically negative effects. One example is Protein-energy malnutrition (PEM), a macronutrient deficiency that is often associated with micronutrient deficiencies. For this reason, most nutritional scientists believe that the long-term solution to under- and malnutrition will be achieved only when all people have access to a balanced, varied and plentiful diet that meets the known nutritional requirements.
There is no single solution to the problem of undernutrition and malnutrition. One approach undertaken by plant scientists, have been to improve the macro and micronutrient content of staple crops consumed in developing countries. In addition to the natural variation present in crop germplasm, modern biotechnology tools are also being used to develop these more nutritious crops. Crops that have been nutritionally enhanced through either modern biotechnology or conventional breeding can be thought of as being biofortified (Chassy, 2007). They have inherent fortifications in which the level of a nutrient in the crop is enhanced above that normally present. The new varieties developed through modern biotechnology have been described with various terms, including genetically modified (GM or GMO), genetically engineered (GE or GEO), transgenic, biotech, bioengineered, recombinant and plants with novel traits (PNT). Value added traits engineered in crop plants include resistance to fungal and viral diseases and biofortification of their nutritional status (Jauhar and Khush, 2002; Bajaj and Mohanty, 2005). However as with any new technology, genetic engineering and biotechnology is encountering resistance from sections of public. There are concerns about the potential adverse impact of GM foods or organisms on human health and the environment. Although some of the concerns of the public may not be well founded (Jauhar and Khush, 2002; Jauhar, 2006), they will need to be properly addressed. To alleviate these fears, perceived or real, we will need to do a better job of informing the public.
The concept of substantial equivalence has been accepted as the cornerstone of the health hazard assessment of GM foods (OECD, 1993). Substantial equivalence is the most practical approach to address the safety of foods or a food component derived from GM crops and is based on the comparison of the phenotypic and compositional characteristics of the parent crop and GM crop. Basically, three categories of GM crops can be considered (a) GM crops which have the same composition as the parent crop, (b) Gm crops which have the same composition as the parent crop with the exception of a well defined trait, and (c) GM crops which are different from the parent crop. For the safety assessment of first category of GM foods, only a molecular characterization of the genetic insert is sufficient, where as for the second category a safety assessment of the expressed protein(s) is also required. For the last category an extensive evaluation involving bioavailability and wholesomeness studies are required, besides the molecular characterization and safety assessment of expressed protein(s) and their products. By molecular characterization is meant the position, nature, stability and number of copies of the inserted DNA. Substantial equivalence is established by the determination of the phenotypic characteristics (e.g. resistance against diseases, agronomic properties) and the complete chemical composition the plant including nutrients, toxicants, antinutrients, and the allergens. The toxicity of the expressed protein(s) is assessed by their homology with known protein toxins, degradation in the gastro-intestinal tract, stability to food processing and acute toxicity in rodents. The possible allergenicity of the expressed proteins is evaluated by comparison of their amino acid sequence with that of known allergens and determination of their stability to digestion and food processing. If the source of genetic insert is allergenic then the use of solid-state immunoassays, skin prick tests and even food challenges can be considered (Martens, 2000).
Traditional Breeding Vs Genetic Modification
Genetic engineering of crops became available in early 1980’s as genetic engineering techniques were being perfected. The advantage of genetic engineering is that it allows the transfer of a single gene, or a couple of genes, in a much more precise, controllable and predictable way than is achievable through traditional breeding. Conventional breeding involves random mixing of tens of thousands of genes present in a plant with tens of thousands of genes present in another plant. In contrast, genetic engineering is a much more precise way of improving crops. Improvements can be achieved in much shorter time frames. In the past, it took 10 to 15 years to introduce a variety of sweet corn. This time has been cut in half using the tools of genetic engineering. In addition, genetically engineered crops are required to undergo extensive food and environmental safety assessment; where as conventional modified crops are not.
One could ask why we need biotechnology when we have been making incredible achievements in our food supply using conventional methods. To answer this question, we have to realize that, today, over 800 million people face daily hunger, furthermore a majority of global population growth in next 50 years will be in developing countries where malnutrition is already prevalent (Chassy, 2002). Forty percent of world’s use for agriculture is already seriously degraded (Serageldin, 1999). In order to meet the nutritional needs of this growing population, cereal production alone will be needed to increase by 40% in next 20 years (Chassy, 2002). We simply cannot achieve the kinds of yield increases in a sustainable way using traditional methods of breeding. Biotechnology is an important tool in addition to all the other tools to produce a food supply that will be sustainable in the long run and will be able to meet these needs in the future (Serageldin, 1999; Borlaug, 2000).
Efforts are being made towards biofortification of crop plants using tools of biotechnology, and levels of nutrients have been increased. Genetic engineering was employed to raise the micronutrient content of rice, the staple food of more than one-third of world’s population. Rice grains normally do not contain beta-carotene, which is the precursor of vitamin A. However; they contain geranyl pyrophosphate that can be sequentially converted to beta-carotene by four enzymes. By engineering rice with four genes for these enzymes , two from daffodil and two from bacterium Erwinia uredovora, Potrykus and his collaborators instructed rice to produce vitamin A. Later, by incorporating the iron-synthesizing ability in it, they were able to produce rice grains rich in vitamin A as well as iron (Ye et al. 2000; Beyer et al. 2002). The resulting rice, called Golden rice, has the potential of saving millions of lives and averting blindness among millions of children, and is therefore referred to as the “grains of hope”. Other transgenic strains with improved nutritional quality have been produced in both japonica and indica rices (Datta et al. 2003), and this strategy is being applied to other cereal crops (Polliti et al. 2004). Paine et al. (2005) developed golden rice 2 by incorporating a phytoene synthase gene (psy) from maize in combination with the Erwinia uredovora gene used to generate the original golden rice. They observed a 23-fold increase in total carotenoids compared to golden rice.
The potato is the most important noncereal food crop for human consumption and, therefore, the need to improve its nutritional quality cannot be overemphasized. Chakraborty et al. (2000) demonstrated that expression of AmAl gene ( from Amaranth, Amaranthus hypochondriacus L.) in transgenic tubers resulted in a significant increase in most essential amino acids as well as in higher protein content in tubers as compared to nontransgenic potato plants. Through metabolic engineering, Ducreux et al. (2004) produced high carotenoid potato tubers containing enhanced levels of beta-carotene and lutein. By incorporating three genes from algae and mushroom species, a “super healthy” Cress was created (Pilcher, 2004). Using a novel transgenic approach involving organ specific gene silencing in tomato, Davaluri et al. (2005) have significantly increased the content of both carotenoids and flavonoids, which are highly beneficial for human health. It is encouraging to note that numerous GM foods are making a valuable contribution to human nutrition (Bouis et al., 2003; Jauhar, 2006).
Since biotechnology is playing a significant role in nutritional enhancement of certain human foods, which has direct bearing on human health, there are some other areas, also directly related to human health, in which modern biotechnology has potential applications. Tools of biotechnology can help accomplish genetic modifications and improvements in plants, hitherto impossible to achieve by cytogenetics and conventional plant breeding. Some of these remarkable applications of biotechnology are outlined below
Vaccines have saved millions of lives and thus played a tremendous role in human health for almost 200 years (Jauhar, 2006). Such vaccines could help save animal lives as well by providing protection against contagious viral diseases such as rinderpest. Khandelwal et al. (2004) developed transgenic peanut (Arachis hypogea L.) expressing hemaggluttinin (H) protein for rinderpest virus. Oral immunization of mice with transgenic peanut induced H specific antibodies, indicating potential for producing an edible vaccine for rinderpest. Modern biotechnology may contribute towards the production of inexpensive edible vaccines. Lack of refrigeration poses a major problem for vaccinating the poor in less developed countries because the heat makes drugs lose their efficeiency. Researchers worldwide have been focussing on producing plant based vaccines that can be eaten uncooked in such fruits and vegetables as melons, tomato and banana.
With appropriate genetic engineering, certain food crops could provide immunization against deadly diseases like, hepatitis or tuberculosis. Edible vaccines against measles, cholera and hepatitis B are being developed in India (Kumar, 2005). Charles Arntzen, of the Biodesign institute at Arizona state University has genetically engineered potatoes to produce a vaccine against hepatitis B virus, which kills one million people very year. He reported that in a trial of an edible vaccine, up to 60 % of the volunteers who ate chunks of raw potato developed antibodies against the virus ( Ariza, 2005; pers comm. Feb. 2006). Vaccines against pneumonia and bubonic plague orally immunogenic to mice have also been developed (Alvarez et al. 2006). Horticultural crops may well serve as vaccine factories and we may see a day when, instead of an injection, one may only need to eat a banana or perhaps a tomato (Jauhar, 2006).
Genetic Fecaffeination of Coffee
Tea [Camelia sinensis (L.) kuntze] and coffee (Coffea arabica L.) provide some of the most widely used beverages in the world. As much as people like to have tea or coffee, some of them would like to have little or no intake of caffeine, an important stimulant in both tea leaves and coffee beans. Caffeine can cause occasional side effects, including elevated blood pressure and heart palpitations (kato et al., 2000). Therefore the demand for decaffeinated tea and coffee has been increasing in recent years. The commercial method of decaffeination currently available is not only expensive; it leaves certain chemical residues and may also lead to loss of flavor for discerning consumers.
Methods of genetically decaffeinating coffee have been tried with remarkable success. Caffeine synthase is an enzyme that catalyzes the final two steps in caffeine biosynthesis pathway. Kato et al. (2000) cloned the gene encoding caffeine synthase from young leaves of tea, paving the way for creating tea and coffee plants that are naturally deficient in caffeine. Decaffeinated coffee is growing on genetically modified bushes that could yield coffee beans in 3-4 years (Ogita et al., 2003; pilcher, 2003) and these transgenic beans could rival industrial decaffeination if they gain public approval (Silvarolla et al. 2004).
Reducing Allergenicity of Crop Plants
The public has some concerns about creation of new allergens in GM foods, although natural foods like peanut are known to produce more allergic reaction in some people. It has been shown that genetic engineering in fact can make a food less allergenic. Soybean, for example is known to cause allergies in humans. Herman et al. (2003) used the transgenic induced gene silencing to shut down the gene that codes for protein believed to cause most soybean allergies. This novel approach to reduce allergies should add nutritive value to the crops.
Biotechnology has found widespread application in various fields of agriculture like induction of disease and pest resistance, control of fungal and bacterial pathogens, pathogen derived resistance to viral diseases, tolerance to abiotic stress in addition to genetic engineering of Christmas trees (Jauhar, 2006). In addition to this, widespread contamination of the environment caused by manufacture, testing and disposal of explosives, which is becoming a matter of serious concern can also, be checked to some extent by use of biotechnology. Certain soil bacteria are known to have biodegradative capability. Scientists in England successfully introduced pentaerythritol tetranitrate reductase, the bacterial enzyme initiating degradation of explosive residues, into plants, and the transgenic plants so created were used for bio-remediation of contaminated soils (Rosser et al., 2001; Wong, 2001). Such an application of biotechnology has great promise for cleaning the environment.
As documented above, tools of modern biotechnology have already produced encouraging results in accelerating crop improvement and moreover this technology has potential application in various other fields of agriculture and environment. Unfortunately however, this relatively new technology is facing resistance from certain sectors. Attempts have been made to create fear about the potential adverse impact of GM foods or plants on human health and environment (Borlaug, 2000; Falk et al. 2002; Jauhar and Khush, 2002) to the extent that GM experimental materials are being destroyed ( Pilcher, 2003). Although the concerns or perhaps misconceptions of certain groups may not be valid, these issues must be adequately addressed to satisfy the general public. Some of the perceived dangers of transgenic technology are discussed below
Issues of Human Health
A major concern is the possibility or perception of health risks posed by GM foods. However, the safety record of transgenic crops and their products testifies to their wholesomeness. There is no report so far of anyone falling ill by consuming GM food, which millions of people consume everyday. In the USA, more than 60% of the processed foods contain transgenic ingredients, but not a single transgenic product has been shown to have any harmful effects (Vasil, 2003). Thus regardless of consumer concerns, it remains true that GM foods have not made anybody sick (Radin, 2003). Additionally, the British Medical Association reaffirmed that there is no evidence that GM foods pose any threat to human safety (the observer, 25 may 2003). There is overwhelming evidence that the bacterium Bacillus thuringiensis and the transgenic crops expressing the cry genes do not pose a threat to human health (De Maagd, et al., 2005). In contrast, in an extensive study by the American Medical Association, 20% of the 548 drugs approved for human use during the past 25 years were later fond to have serious or life-threatening effects, some possibly contributing to 1002 deaths (Vasil, 2003).
Genetic Pollution of Related Plants
Another major concern is the potential for unwanted movement of a transgene from a genetically engineered crop plant to its relatives-whether cultivated or wild. Thus a transgene for herbicide resistance could get incorporated into a wild relative; thereby creating a “super weed” that might be hard to control. Possibility of such genetic pollution through a misplaced transgene exists in some cases (Stewart et al.,2003; Armstrong et al.,2005), but in most cases it is unlikely to happen because of the difficulty of hybridization between a transgenic crop plant and its wild relatives and the need of embryo rescue to obtain a hybrid under laboratory conditions ( Jauhar and Khush, 2002). Nevertheless, some gene flow does occur from transgenic rice to its wild relatives or to other rice cultivars (Song et al.,2003; Zhang et al.,2003), but this should not be a serious cause for concern. Several genes for insect pest resistance and disease resistance have, for example, been transferred to cultivated rice using traditional breeding. However, it must be noted that so far there is no known cause where wild or weedy biotypes of rice, such as red rice, have become more resistant by outcrossing with cultivated rice ( High et al.,2004).
Tinkering With Nature
Transgenic technology as a means of introducing new genes into plants is considered by some as tinkering with nature. This technology is considered to be “inherently and morally wrong” (Hackett, 2002). However, we must remember that humans, in their effort to ensure and improve food production, have been tinkering with nature for centuries. Traditional plant breeding involving selection pressure for the most suitable and desirable crop cultivars constitutes tinkering with nature and it is in essence human-made evolution (Jauhar, 2006). Any breeding activity is accompanied by genetic modifications, which in the last analysis involves changes at DNA level. The newer biotechnological tools for gene transfer into crop cultivars are in fact, refinement of earlier ones, and genetic enhancement by those techniques poses no greater risk to the consumer (Jauhar, 2006). Many of the current crop cultivars we consume do, after all, contain genes of alien origin (Jauhar and Khush, 2002).
Issues to be considered for the safety and nutritional assessment of GM plants and derived foods and feed have been identified in the Guidance document of the Scientific Panel of Genetically Modified Organisms of the European Food Safety Authority (EFSA, 2004), including
The “safety of the source organism” is considered first. One might assume that a gene or genes that are derived from commonly eaten food crop would not provoke the same degree of scrutiny as would the genes from a highly toxic source. In practice the degree of scrutiny is the same. Risk is minimized if the gene products intended for introduction have been characterized and their function and metabolic fate established (Chassy, 2002). It is given that they should not encode toxins, antinutrients or other potentially physiologically hazardous activities.
There are few safety issues associated with the ingestion of the newly introduced DNA per se there exist no reported incidents in which the DNA has been shown to be toxic (Chassy, 2002). Despite fears and claims to the contrary, there are also no known instances of plant derived DNA being taken and incorporated into the mammalian genome (Beever and Kemp, 2000). Dietary DNA is usually degraded when consumed and is quickly hydrolyzed and digested to nucleotides in the human gastrointestinal tract (Beever and Kemp, 2000).
New genes are incorporated into transformed plants in order to confer new desirable traits to the plants. Almost without exception, these traits are the result of transcription and translation of the genes to synthesize newly acquired proteins in the plants. Toxicological evaluation is routinely performed on purified preparations of the recombinant proteins that have been newly introduced.
Substantial Equivalence in Safety Assessment of GM Foods
The first successful genetic modification of a plant was reported in 1983. It was a tobacco plant in whose genome a foreign gene had been inserted which resulted in an antibiotic resistance phenotype (Horsch et al., 1984). The first genetically modified food – the famous Flavr SavrTM Tomato- was placed on the US market in 1994. Currently more than fifty genetically modified crops plant varieties have been commercialized, among them different types of genetically modified tomatoes, soybean, maize, rapeseed and potatoes. Their new traits are mainly of agronomic interest, i.e., herbicide or insect tolerance. However usage of herbicides and pesticides are attracting the interest of consumers as well. Preceding the first commercialization of a food derived food genetically modified organism (GMO), criteria for assessment of its safety have been discussed intensively by those international and national organizations with competence in food safety issues. Guidelines for the safety assessment of foods derived from modern biotechnology have been elaborated by the World Health and Food and Agriculture Oraganizations (WHO and FAO), the Organization for Economic Co-operation and Development (OECD), the International Food Biotechnology Council (IFBC), the International Life Science Institute (ILSI), the US Food and Drug Administration (FDA), the UK Advisory Committee on Novel Foods and Processes (ACNFP), the Nordic Council, the German Research Community and other national bodies. These organizations base their recommendations for the safety assessment of a modified organism on comparison with the non-modified counterpart in order to identify equivalencies and differences ( Schauzu, 2000).
The term substantial equivalence was first mentioned in connection with food safety in report of the OECD group of national experts on safety in biotechnology (OECD, 1993). The members of the group agreed that the most practical approach to determining the safety of foods derived by modern biotechnology is to consider whether they represent a substantial equivalent to analogous traditional products. The term substantial equivalence and the underlying approach were borrowed from the US Food and Drug Administration (FDA). Definitions of a class of new medical devices that do not differ materially from their predecessors thus, don’t raise new regulatory concerns (Miller, 1999). According to the OECD definition, the concept of substantial equivalence is based on the idea that existing products used as foods or food sources can serve basis for a comparison when assessing the safety and nutritional value of food or food ingredients that has been modified by modern biotechnological method or is new. It implies that if a novel food or novel food component is found to be substantially equivalent to an existing food or food component, it can be treated in the same manner with respect to safety. No additional safety concerns would be expected. If a novel food or novel food ingredient has not been found to be substantially equivalent to its conventional counterpart this doesn’t imply that it is unsafe. It is then to be evaluated on the basis of its unique composition and properties (OECD, 1993).
Since a genetic modification is aimed at introducing into organisms the result will always be a different composition of genes and proteins. The most reasonable interpretation is that a food derived from a GMO is considered substantially equivalent to its traditional counterpart if the genetic modification has not resulted in intended or unintended alterations in the composition of relevant nutrients and inherent toxicants of the organism, and that the new genes and proteins have no adverse impact on the dietary value of the food and do not therefore pose any threat to the consumer or the environment (Jonas et al., 1996). The concept of substantial equivalence can thus be considered no more but also no less than a reasonable tool to assess the nutritional comparison and safety of a novel food in relation to the nutritional composition and safety of its traditional counterpart. This is consistent with Novel Food Regulations requirements that foods and food ingredients falling within its scope must not present a danger to the consumer, must not mislead the consumer and do not differ from the food or food ingredients which they are intended to replace to such an extent that their normal consumption would be nutritionally disadvantageous to the consumer (Schauzu, 2000)
The concept of substantial equivalence was applied for the first time to a GMO in the safety assessment of the Flavr savrTM tomato before it was placed on the US market in 1994. Data collected from field trials and analyses of the molecular and chemical composition showed that the genetically modified tomato was equivalent to the non-modified parent plant, with the exception of newly introduced traits, which were then the subject of further studies in order to establish food safety. The data were presented and the food safety of genetically modified tomatoes was accepted in consultation with the FDA (Schauzu, 2000).
The safety assessment is always based on a comparison of the modified food to its traditional counterpart in terms of molecular, compositional, nutritional and toxicological data. The level of detail of the analyses required depends on the degree to which the new product differs from the traditional counterpart. Thus, the extent of analyses may differ and therefore there is no general checklist that could be followed by those who are responsible for allowing the product to be placed in the market.
In order to detect any unintended modifications which could have resulted from the insertion of the newly introduced DNA sequences due to interruption or enhancement of regular gene functions, the chemical compositions as well as the phenotypic characteristics of the GMO need to be checked.
Analytical studies of the composition of novel food and food ingredients are of crucial importance not only for the establishment of substantial equivalence, but also as a prerequisite for the nutritional and the toxicological assessments. The compositional analysis should focus particularly on the determination of the content of critical nutrients and any critical toxicants and anti-nutritional factors, which might be either inherently present or process derived.
The crucial importance of compositional analysis and thorough knowledge of the nutritional properties of the novel food as a prerequisite toxicological studies can be demonstrated by the genetically modified potatoes expressing the lectin Galanthus nivalis agglutinin (GNA) which had been fed to rats in a disputed study undertaken by Stanley W.B. Ewen, university of Aberdeen, UK, and Arpad Pusztai at the Rowlett Research institute at Aberdeen, UK, in order to examine whether the GNA gene insertion had affected the nutritional and physiological impact of potatoes on mammalian gut ( Ewen and Pusztai, 1999). The researchers found that the diets containing the genetically modified potatoes had variable impact on different parts of the rat’s gastrointestinal tract, particularly on the small intestine and caecum. This was not observed in control rats, which were fed on non-modified potatoes or non-modified potatoes supplemented with GNA. The authors assume that not only the GNA in potatoes but also other parts of the vector or the transformation itself could have contributed to the overall effects ( Ewen and Pusztai, 1999). Unfortunately, apart from shortcomings in the study, data on composition of different GM potato lines used in the diet are not reported in the publication. Some details released on the internet by Pusztai (1999) indicate that the composition of genetically modified potato lines differed substantially from that of parental line. The results of the data were assessed by the UK Royal Society, which found the data to be inadequate because they were not clear about the differences in chemical composition between strains of non GM and GM potatoes and invalid because of technical limitations of the experiment and the incorrect use of statistical tests (The Royal society, 1999). In spite of the wide public attention these researchers have attracted, the use of their results is limited, to say the least.
Toxicity and Allergenicity of New Proteins
New proteins have to be characterized with regards to their toxic or allergenic potential. Under these procedures, existing immunological tests are being applied to the foreign proteins if they are expressed by the genes derived from a source known to be associated with food allergy. For new protein with no history of food use, the procedure requires that the properties of new proteins are compared with those of known toxicants and allergens. As a first step, a comparison of the amino acid sequences of new proteins with known toxins and allergens will reveal homologies. Another important factor is the quantification of new protein contained in the food.
Food allergens share further specific characteristics. They are quite stable against high temperatures, low pH and proteolytic degradation. One of the most relevant tests here is a model of in vitro digestion for measuring resistance to proteolysis. Applied to the main known food allergens, this test shows that they are stable, whereas the new proteins expressed in genetically modified plants are rapidly degraded. So it can be assumed with a reasonable amount of certainty that the GMOs which contain these new proteins do not represent an extra allergenic risk. But then, of course the available tests do not guarantee non-allergenicity ( Schauzu, 2000)
Further toxicological test requirements need to be considered on a case-by-case basis, taking into account the source familiarity and characteristics as well as the amount of new protein contained in the food and results of the compositional analysis of the food.
If no equivalence to conventional food components can be established, the products have to be subjected to an extensive nutritional and toxicological assessment including studies on toxicogenetics, genotoxicity, and reproductive and developmental toxicity, as well as short-term and long-term carcinogenicity feeding studies with rodents. The necessity for other toxicity studies, including studies with a second species, will depend on the concern level, which is determined by the chemical structure and the intended level of human exposure ( Jonas et al., 1996).
Antibiotic Resistance Genes
Antibiotic Resistance Markers (ARM) are used to help identify the transformed plants after the transformation (DNA introducing process) . Plants that have incorporated the new DNA, including the ARM, will grow in culture that contains the antibiotic. Transformed cells containing the desired newly introduced genes can then be selected for further study. Concerns have been raised about the safety of using ARM in crops produced through biotechnology. Some fear that ARM genes will transfer to bacteria in the soil and gut and give rise to increased levels of antibiotic resistance. Transfer of plant DNA to bacteria has never been observed in nature, nor has it been possible demonstrate transfer in laboratory experiments (Chassy, 2002). More importantly and unfortunately, antibiotic resistance genes are already widespread in nature. Kanamycin resistance, a marker that is often used in biotechnology, is often present in 10% or more of bacteria randomly isolated from soil (Chassy, 2002). Misuse and poor stewardship of antibiotics in agriculture, veterinary and human medicine may have led to the widespread dissemination of ARM genes in nature. There is certainly cause of concern about the indiscriminate use of antibiotics that has led to this situation, but plants containing ARM genes are highly unlikely to contribute to the problem. Banning the use of ARM genes in biotechnology is unlikely to improve the situation ( FAO/ WHO, 2001). To address these concerns biotechnologists are developing alternative selection systems that do not utilize ARM genes.
Animal Feeding Trials with Whole GM Foods/Feeds
In case the composition of a new food/ feed has considerably been altered or remaining uncertainties exist on the potential occurrence of unexpected changes in the composition of the new food, the performance of animal testing of the whole food/ feed may be considered (EFSA, 2004). However, given the many difficulties encountered in this type of bioassay ( FAO/WHO, 2000; Kuiper et al., 2001; Chassy et al., 2004), the significance of this type testing with respect to its sensitivity and specificity to detect unexpected effects should not be overestimated. A thorough compositional analysis using single-compound analysis and, where appropriate, profiling methods as described above give more confidence as to whether unexpected effects in the new food/ feed might have occurred. On a case by case basis feeding trials with livestock species may be considered, depending on the trials to be assessed.
The current comparative safety assessment procedure provides assurance of safety and quality by identifying similarities and differences between the new food or feed crop and a conventional counterpart with a history of safe use. The similarities noted these processes are not subject to further assessment. The identified differences then become the focus of new scientific assessment. Chassy et al., (2007) recommended the following for nutritional and safety assessment of nutritionally improved foods through biotechnology which can be applied to GM foods and feeds in general.
The safety assessment of a nutritionally improved food or feed begins with a comparative assessment of the new food or feed crop with an appropriate comparator crop that has a history of safe use.
To evaluate the safety and nutritional impact of nutritionally improved food and feed crops, it is necessary to develop data on case by case basis in the context of the proposed use of the product in the diet and consequent dietary exposure.
The safety of any novel protein(s) needs to be assessed.
Compositional analysis of crops with known toxicants and antinutrient compounds should include analysis of those specific analytics. If warranted, an evaluation of targeted metabolic pathway should also be conducted to identify specific metabolites for inclusion in the compositional analysis due to safety and/or nutritional considerations.
The appropriate phenotypic properties of the nutritionally improved crop need to be assessed when grown in representative production locations as part of the overall comparative safety assessment process. Further study is warranted if significant unintended and unexplainable differences between the improved crop and an appropriate comparator are identified.
Studies with laboratory animals can confine observations from other components of the safety assessment, thereby providing a sense of added safety assurance, although they may lack the sensitivity to reveal the unintended minor changes.
While feeding studies with target livestock species are not the part of the safety assessment, they are important to demonstrate the expected nutritional benefit of nutritionally enhanced feed crops.
Pre market studies on humans might be appropriate on a case-by-case basis to assess the nutritional effectiveness of nutritionally improved crop in those cases where alteration by conventional breeding would trigger similar studies.
Pre market assessment regarding the impact of the introduction of an improved nutrition crop on the nutrient intake of the consumers may often be appropriate ( for example, when changes in agricultural practices or changes in consumer led dietary intakes are anticipated).
The scientific assessment of the possible consequences of the adoption of improved nutrition crops should balance not only assessing the potential risks but also considering the opportunity for benefits to alleviate undernutrition for a potentially large number of people.
Future Challenges in the Assessment of the Safety of GM Foods
Current safety assessment methodologies are focussed primarily on the evaluation of the safety of single chemicals. Food is a complex mixture of many chemicals. Using animal models, the evaluation of most aspects of the safety of single component of the diet, such as a Bt toxin , is possible using widely protocols. Future projects may involve more complicated manipulations of plant chemistry. In this case, safety testing will be more challenging. Whole foods can not be tested with dose strategy currently used for single chemicals to increase sensitivity in detecting toxic end points (MacKenzie, 1999; Royal Society of Canada, 2001). Also, the question of potential deleterious interactions between new or enhanced levels of known toxic agents in GM foods will undoubtedly be raised. The safety testing of multiple combinations of chemicals remains a difficult proposition of toxicologists. In view of these messages, there is a clear need for the development of effective protocols to allow the assessment of safety of whole foods (Royal Society of Canada, 2001).
Although the science indicated that no new or different risks are present, new more rigorous regulatory processes are used to assess the food, feed and environmental safety of crops developed via biotechnology. Regulators, scientists and the industry choose to be on the side of precaution. It is ironic, and then that critic’s challenge a more precautionary approach should be taken. There are several excellent websites that describe the regulatory process in detail (CAST, 2001). There are nine steps in the US regulatory process (CAST, 2001).
It takes 7 to 10 years to navigate the regulatory waters, and in US, three government agencies- the USDA, EPA and FDA are involved. There are several public hearings, and there is some opportunity for some public input into the process. Opportunity for public input, transparency of the process and availability of the information could, however, be improved so that there could be no misleading about the nature of regulatory process. There is one exception to the FDA authority to regulate the food safety of biotechnology derived crops. The EPA has the responsibility of food safety of bacterial proteins present in insect protected products such as Bt corn. These insect toxic proteins were once called plant pesticides but are now classified as plant protectants (Chassy, 2002).
Biotechnology has made rapid strides since it came into being some 20 years ago and since the release of first transgenic plants. Currently, we have efficient transformation protocols for a variety of plants, which include cereals, legumes, fiber crops, forage crops, fodder crops, ornamentals and forest trees. And genetic transformation provides access to an unlimited pool of desirable genes not previously accessible to breeders. The successful deployment of transgenic approaches to combat insect pests and diseases of important crops like rice, wheat, maize, barley and cotton is a remarkable accomplishment. Biofortification of crops to alleviate malnutrition among poor masses constitutes another exciting development. Thus the development of Golden rice, which is genetically enriched with vitamin A and iron and has a real potential of saving millions of lives in impoverished countries , is a major milestone in tackling the problem of world hunger ( Potrykus, 2001; Sharma et al.,2003). Yet another exciting application of the transgenic technology is the development of edible vaccines for immunization against deadly diseases like hepatitis B and tuberculosis, two of the serious disease of poor masses in Asia and Africa. That genetic engineering can make foods less allergenic should help promote this technology (Jauhar, 2006).
In 2005, one thousand million acres of biotech crops were planted worldwide and they now cover the equivalent of 40% of the US land area, and according to the International Society for Acquisition of Agro-biotech Applications (ISAAA) the area planted with biotech crops increased by 9 million hectares in 2006 (www.isaaa.org). However, as with any other new technology, genetic engineering is not without adversaries, some of which even go as far as destroying experimental material. This antiscience zealotry (Borlaug, 2000) and public hostility to modern biotechnology has been attributed to “lack of scientific literacy” (Bucchi and Neresini, 2004) and may impede human progress (Jauhar, 2006). The opponents of new technology work on the premise that the modern biotechnology is unnatural, unsafe and inherently wrong and that it results in unsafe products. However, the indisputable fact remains that the conventional breeding is a form of genetic engineering that has been practiced for centuries in humanity’s quest for food production and any breeding activity is accompanied by changes at DNA level. It would therefore appear ridiculous to suddenly get nervous about genetically altering crops now when we have been doing pretty much the same thing for centuries. There is no evidence to suggest that GM foods pose any new threat to human safety, although work needs to be done on informing and reassuring the public about the global benefits of GM crops.
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