Biosafety deals with the safe and environmentally sustainable use of all biological products and applications for human health, biodiversity, and environmental sustainability in support of improved global food security. Currently, for the general population, there are special issues of concern in regard to the biosafety of the products derived from biotechnology. These issues seem to be important only with regard to the products of genetic engineering (since molecular markers and marker-assisted breeding result usually in products that are equal to varieties created through the regular breeding procedures). It is called transgenic, an organism in which a foreign gene (a transgene) is incorporated into its genome. The transgene is present in both somatic and germ cells, is expressed in one or more tissues, and is inherited by the offspring in a Mendelian fashion. Transgenics are also called "genetically modified organisms" or GMOs.

Some of the potential health risks associated with transgenics are:

• Allergenicity of the product of the introduced gene or genes. The nature of the allergenicity, in the few cases where it appeared, was the same as the allergenicity caused by the nontransgenic product coded by the transferred genes in the original species. The best known case involves a soybean variety that was transformed by a Brazilian nut gene, with the intention of enriching the soybean protein with methionin, an amino acid for which soybeans are deficient. Brazil nuts are allergenic, and the transformed soybeans showed the same allergenic compound that is present in Brazil nuts. A test against that allergenic compound allowed the identification of the problem and avoided the release of the modified soybean (FAO, 2001).

• Unexpected production of a toxic component due to the insertion of the new sequence (disruption or activation of gene sequences or of regulators). Analysis of the whole protein profile of the new organism and "in vivo" tests with experimental animals could identify the problem when it arises. In most cases, the utilization of proper insertion sequences through site-specific recombination will possibly prevent this problem.

• Expression of a gene product in undesired locations. An example of this is the production of the Bt toxin of Bacillus thuringiensis in the pollen grains of corn. This expression occurs because promoters that are not tissue specific are used (e.g., the 35S promoter). The utilization of tissue-specific promoters, which will be available for the "next generation" of genetically modified organisms should totally overcome the problem.

• Antibiotic resistance transferred from GMOs to bacteria in the human gut. Antibiotic resistance genes have been used in one of the steps for the production of the "first generation" GMOs. While the probability of such transfer is extremely low, it is theoretically possible (although not proven in practice). Because of this, the utilization of these genes is discouraged, and the new transgenics that are being currently produced are being made without the use of such markers.

A scientific panel commissioned by the British Ministry of Agriculture concluded that the risks to human health from GMO crops on the market are very low at the time of the analysis (GM Science Review Panel, 2003). However, it also concluded that on the crops developed GMOs may present greater challenges in risk management in the future.

Besides the health effects mentioned above, when making risk assessment of transgenics, all methods by which they have been produced should also be considered. There are many different procedures for DNA and/or RNA isolation, cloning, multiplication, introduction into a transmission vector, and insertion into other host organisms. The safety of the resulting organism should be evaluated according to its proposed use and in relation to the implications for health and for the environment. Additionally, questions to be considered should cover the environment in which it should be tested and released. The procedures must be examined carefully, and the properties of the organism in the environment analyzed. During this examination and analysis, one should try to anticipate any possible routes of escape (animal movement, pollen exchange, breakage, and transport of plant parts), any potentially harmful consequence for humans that may ingest or have contact with it (food safety, irritants, allergenics) and any harmful consequence for other species in the ecosystem that may somehow interact with it. When a transgenic is considered safe, it should be safe for all intended regular uses and for the environment for which the risk analysis was made. The Codex Alimentarius Commission, which is a joint FAO/WHO Commission, has recently created a task force to help countries to create and establish food safety standards for food derived from GMOs. Among options for enforcing compliance with such standards are inspections and audits, imposition of administrative and monetary penalties, and trade sanctions. However, significant practical, technical, and economic limitations mean that ensuring compliance is no easy task (McLean et al., 2002).

In addition to potentially negative impacts on human health, transgenics may also have some adverse impacts on ecosystems in general. Some of the potentially negative environmental impacts of the adoption of transgenics are:

• Displacement of local biodiversity and elimination of existing forms as new improved genotypes are adopted and old landraces are abandoned. This displacement has been occurring ever since new genotypes were first produced through traditional breeding procedures and does not represent a particular problem caused by the use of transgenics. Displacement is also caused by the introduction of alien species that are highly aggressive or competitive in comparison with the existing ones.

• Transgenic escape (due to natural out-crossing) may result in the creation of new plagues, especially in the creation of new weeds in the case of plants, or increased aggressiveness of previously existing weeds. This increase can happen only when there are wild relatives of the transgenic crop in the same area, such as in the center of origin or of diversity of the crop species.

• Harmful effects on nontarget species and waste of biological resources refer to possible effects on the population of pollinators, predators, sym-bionts, natural enemies, etc.

• Perturbation of biotic communities and adverse effects over the ecosystem that may happen whenever a new life form or genotype is introduced into an environment new to it. Since a genetically modified crop (e.g., maize) tends to behave in a way that is similar to the nonmodified variety, the introduction of an unmodified new species causes a more significant disturbance on the ecosystem than the introduction of a transgenic variety of a previously existing species in that environment. The need for biosafety evaluations prior to the release of genetically modified genotypes (in particular, transgenics) significantly delays their utilization and significantly increases research costs. In some cases the added costs may be so high that the eventual advantage of using the transgenic may not be worthwhile. These facts should be considered before engaging in any research using these techniques.

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