Food Safety of Genetically Modified Foods

Genetically Modified Foods

For thousands of years, humans have been genetically enhancing other organisms through the practice of selective breeding. Our ability to manipulate plants by introducing new genes promises innovative solutions to many real-world problems. Yet there is considerable opposition to the use of genetically modified plants for food production and other uses. Genetic engineering offers a time-saving method for producing larger, higher-quality crops with less effort and expense. Yet such benefits must be balanced against the risks of changing the genetic makeup of organisms. Genetically modified organisms (GMOs) can be defined as organisms (i.e. plants, animals or microorganisms) in which the genetic material (DNA) has been altered in a way that does not occur naturally by mating and/or natural recombination. The technology is often called “modern biotechnology” or “gene technology”, sometimes also “recombinant DNA technology” or “genetic engineering”. It allows selected individual genes to be transferred from one organism into another, also between nonrelated species. Foods produced from or using GM organisms are often referred to as GM foods.

GM foods are developed and marketed, because there is some perceived advantage either to the producer or consumer of these foods, which is meant to translate into a product with a lower price, greater benefit (in terms of durability or nutritional value) or both. Initially GM seed developers wanted their products to be accepted by producers and have concentrated on innovations that bring direct benefit to farmers and the food industry generally. One of the objectives for developing plants based on GM organisms is to improve crop protection. The GM crops currently on the market are mainly aimed at an increased level of crop protection through the introduction of resistance against plant diseases caused by insects or viruses or through increased tolerance towards herbicides.

Benefits of GM Foods

In BT Corn, resistance against insects is achieved by incorporating a specific gene from the bacterium Bacillus thuringiensis (Bt) which produce toxin against insects. This toxin is currently used as a conventional insecticide in agriculture and is safe for human consumption. The GM crops inherently produce this toxin have been shown to require lower quantities of insecticides in specific situations, e.g. where pest pressure is high. Virus resistance is achieved through the introduction of a gene from certain viruses which cause disease in plants. Virus resistance makes plants less susceptible to diseases caused by such viruses, resulting in higher crop yields. Herbicide tolerance is achieved through the introduction of a gene from a bacterium conveying resistance to some herbicides. In situations where weed pressure is high, the use of such crops has resulted in a reduction in the quantity of the herbicides used.

The release of GMOs into the environment and the marketing of GM foods have resulted in a public debate in many parts of the world. This debate is likely to continue, probably in the broader context of other uses of biotechnology (e.g. in human medicine) and their consequences for human societies. Even though the issues under debate are usually very similar (costs and benefits, safety issues), the outcome of the debate differs from country to country. On issues such as labelling and traceability of GM foods as a way to address consumer preferences, there is no worldwide consensus to date. Despite the lack of consensus on these topics, the Codex Alimentarius Commission has made significant progress and developed Codex texts relevant to labelling of foods derived from modern biotechnology in 2011 to ensure consistency on any approach on labelling implemented by Codex members with already adopted Codex provisions.

Standard Practices

Generally, consumers consider that conventional foods (that have an established record of safe consumption over the history) are safe. Whenever novel varieties of organisms for food use are developed using the traditional breeding methods that had existed before the introduction of gene technology, some of the characteristics of organisms may be altered, either in a positive or a negative way. National food authorities may be called upon to examine the safety of such conventional foods obtained from novel varieties of organisms, but this is not always the case. In contrast, most national authorities consider that specific assessments are necessary for GM foods. Specific systems have been set up for the rigorous evaluation of GM organisms and GM foods relative to both human health and the environment. However, similar evaluations are generally not performed for conventional foods. Hence, currently there exists a significant difference in the evaluation process prior to marketing for these two groups of food. The WHO Department of Food Safety and Zoonoses aims at assisting national authorities in the identification of foods that should be subject to risk assessment and to recommend appropriate approaches to safety assessment. Should national authorities decide to conduct safety assessment of GM organisms, WHO recommends the use of Codex Alimentarius guidelines.  

The safety assessment of GM foods generally focuses on:

(a) Direct health effects (toxicity);

(b) Potential to provoke allergic reaction (allergenicity);

(c) Specific components thought to have nutritional or toxic properties;

(d) The stability of the inserted gene;

(e) Nutritional effects associated with genetic modification;

(f) Any unintended effects which could result from the gene insertion.

Major Issues of Concern for Human Health

While theoretical discussions have covered a broad range of aspects, the three main issues debated are the potentials to provoke allergic reaction (allergenicity), gene transfer and outcrossing.

Allergenicity

Many people suffer from allergies to various food items, including nuts, wheat, eggs, or dairy products. There is a concern that the protein products of introduced genes may be toxic or allergenic to certain individuals. As a matter of principle, the transfers of genes from commonly allergenic organisms to non-allergic organisms are discouraged unless it can be demonstrated that the protein product of the transferred gene is not allergenic. While foods developed using traditional breeding methods are not generally tested for allergenicity, protocols for the testing of GM foods have been evaluated by the Food and Agriculture Organization of the United Nations (FAO) and WHO. No allergic effects have been found relative to GM foods currently on the market.

Gene Transfer

Gene transfer from GM foods to cells of the body or to bacteria in the gastrointestinal tract would cause concern if the transferred genetic material adversely affects human health. This would be particularly relevant if antibiotic resistance genes, used as markers when creating GMOs, were to be transferred. Although the probability of transfer is low, the use of gene transfer technology that does not involve antibiotic resistance genes is encouraged.

Outcrossing

The migration of genes from GM plants into conventional crops or related species in the wild (referred to as “outcrossing”), as well as the mixing of crops derived from conventional seeds with GM crops, may have an indirect effect on food safety and food security. As a primary concern, preventing GM versions from mixing with the naturally existing populations of plants from which they're derived is recommended. Because, plants rely on the transfer of pollen, via insects or the air, to breed and produce offspring, and it's difficult to control how they cross-breed in the wild. Cases have been reported where GM crops approved for animal feed or industrial use were detected at low levels in the products intended for human consumption. In most cases, it's not yet clear how introduction of the non-native gene would affect wild populations. However, several countries have adopted strategies to reduce mixing, including a clear separation of the fields within which GM crops and conventional crops are grown.

Different GM organisms include different genes inserted in different ways, which means that individual GM foods and their safety should be assessed on a case-by-case basis, where it is not possible to make general statements on the safety of all GM foods. GM foods currently available on the international market have passed safety assessments which are not likely to present risks for human health. In addition, no effects on human health have been shown as a result of the consumption of such foods by the general population in the countries where they have been approved. Continuous application of safety assessments based on the Codex Alimentarius principles and, where appropriate, adequate post market monitoring, should form the basis for ensuring the safety of GM foods.

When farmers start growing genetically modified crops, they stop growing the old varieties, where these old varieties are important sources of diverse genes that give plants other desirable characteristics. For example, a new pest or disease could come along and destroy the genetically modified rice. If one of the old rice varieties has a gene that makes it resistant, it could be cross-bred to make the saltwater rice resistant as well. If we lose the old varieties, we also lose their useful genes.