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Animal Biotechnology: Science-Based Concerns
expression persist in adult clones and are associated with food safety risks; nor are there substantial analytical data comparing the composition of meat and milk products of somatic cell clones, their offspring, and conventionally bred individuals. Somatic cell cloned cattle reportedly are physiologically, immunologically, and behaviorally normal, and exhibit puberty at the expected age, with high rates of conception upon artificial insemination. The committee felt that it is difficult to identify concerns without additional supporting data using available analytic tests regarding food product composition. In summary, there is no current evidence that food products derived from adult somatic cell clones or their progeny present a food safety concern.
The committee considered environmental issues to be the greatest science-based concerns associated with animal biotechnology (see Chapter 5), in large part due to the uncertainty inherent in identifying environmental problems early on and the difficulty of remediation once a problem has been identified. Any analyses of GE organisms and their potential impact on the environment needs to distinguish between organisms engineered for deliberate release and those that are engineered with the intention for confinement, but escape or inadvertently are released. The discussion in this report focuses primarily on the latter category, but the committee has a high level of concern regarding the intentional release of GE organisms into the environment. The concerns that follow primarily focus on risks resulting from GE animals entering natural environments. The release or escape of GE animals could result in a transgene spreading through reproduction with wild type individuals of the same species. The risk of horizontal gene transfer (i.e., the nonsexual transfer of genetic information between genomes by the vector) is of considerably lower probability but of high risk should it occur in some ecosystems.
The likelihood of a transgenic animal becoming established in the environment is dependent on two factors: a) its ability to escape and disperse in diverse communities, and b) its fitness in that environment. Once a transgene is introduced into a population, natural selection for fitness will determine the ultimate fate of the transgene if the population is large enough to withstand the initial perturbations. Fitness in this context refers not only to the GE organism’s survival, but also to its reproductive ability, including juvenile and adult viability, age at sexual maturity, female fecundity, male fertility, and mating success (i.e., to all aspects of the organism’s phenotype that affect spread of the transgene). The GE organism eventually might replace its relative or become established in that community if it is more fit than its wild relatives in that environment. If it is less fit, the engineered trait eventually will be removed from the receiving population. If the fitness of transgenic and nontransgenic