Transgenic Animals Could Pose Environmental Threat
By Cat Lazaroff
WASHINGTON, DC, August 21, 2002 (ENS) - Genetically engineered animals could pose a serious threat to the environment if they escape and introduce their engineered genes into wild populations, concludes a new report from the National Academies' National Research Council. The report found no evidence, however, that products from cloned livestock are unsafe for human consumption.
The Food and Drug Administration (FDA) requested the report to aid the agency in determining the safety of certain animal biotechnology products, particularly cloned cattle. A 12 member committee from the National Research Council (NRC) reviewed existing science to identify what health and environmental problems might be posed by genetically modified animals.
"It might be impossible to limit which communities a GE organism will gain access to," the committee wrote. "Thus if any of these communities are fragile, the concern will be high that the GE organism will cause environmental harm."
Genetically engineered insects, shellfish, fish and other animals that can easily escape, are highly mobile, and that readily adapt to life in the wild are of particular concern, particularly if they are more successful at reproduction than their natural counterparts. Nonnative insects, fish, mussels, mice and rats have all done extensive environmental damage, suggesting that engineered varieties could have similar effects if they escaped from their breeding facilities.
For example, laboratory tests and computer models have demonstrated that if transgenic salmon with genes engineered to accelerate growth were released into the natural environment, they could compete more successfully for food and mates than wild salmon. Even if only sterile female fish were produced, as proposed by one company now developing transgenic salmon, thousands of engineered fish could readily out compete the handfuls of native salmon that now remain in some streams and rivers.
The engineered animals "might eventually replace its relative or become established in that community if the GE organism is more fit than its wild relatives in that environment," the committee wrote. Regarding engineered shellfish, which produce microscopic offspring, "it is clear that confinement of these aquatic organisms will be difficult and they are likely to escape."
By creating transgenic animals with genes from another species, or by removing or turning off certain genes, animals can be engineered to grow bigger and more rapidly. Animals are also being produced that possess traits beneficial to humans, such as meat with more protein and less fat, eggs with less cholesterol, milk containing pharmaceutical products, or even tissues and organs suitable for human transplantation.
Through somatic cell nuclear transfer - the technique used to clone Dolly the sheep - scientists can create an almost identical copy of an adult animal with desirable traits. The owners of a few hundred cows cloned this way in the United States have been asked by FDA to hold off selling the cows' milk and meat, or breeding them, pending regulatory approval.
So far, no evidence exists that meat or milk products from cloned livestock pose a human health risk, but the committee that wrote the report found it difficult to identify concerns without additional information about food composition, which could be collected using available analytical tests.
"The committee believes that an evaluation of the composition of food products derived from cloned animals would be prudent to minimize any remaining food safety concerns," the report states. "Abnormalities in patterns of gene expression," could exist in cloned animals, but so far, there is no evidence to suggest that this could pose a health concern.
In transgenic animals developed for human consumption, there is a "low probability" that some of the new proteins produced through genes inserted from other species could trigger allergic or hypersensitive reactions in a small percentage of people, the committee wrote. The potential for such problems is difficult to gauge, since it can only be detected once a person is exposed and experiences a reaction.
Allergic reactions to foods range from mild irritation to systemic reactions that can swell tissues, shut down breathing and lead to death, the committee noted. The uncertainty surrounding new proteins, and the potential impact on consumers who may be allergic, is serious enough to elicit a "moderate level of food safety concern," according to the report.
Animals genetically engineered to produce non-food products, such as cows that produce drugs in their milk, are not intended to enter the food supply. But there is some concern that proteins designed to produce a pharmaceutical product in the animal's milk may find their way to other parts of the animal's body, possibly causing adverse effects.
The applications of biotechnology may someday reduce the number of animals needed for food and fiber production, but this is not necessarily good news for animal welfare, the committee noted. For example, calves and lambs produced through in vitro fertilization or cloning tend to have higher birth weights and longer gestation periods, which leads to difficult births often requiring caesarian sections.
In addition, some of the biotechnology techniques in use today are extremely inefficient at producing fetuses that survive. Of the transgenic animals that do survive, many do not express the inserted gene properly, often resulting in anatomical, physiological or behavioral abnormalities.
Although the committee was not asked to make any policy recommendations, it suggested that the current regulatory framework may not be adequate to protect human health and the environment, and noted that the responsibilities of federal agencies for regulating animal biotechnology are somewhat unclear.
"Some people, irrespective of the application of the technology, consider genetic engineering of animals fundamentally unethical," the committee wrote. Regulatory agencies must consider whether they should examine "only the direct health and environmental impacts of biotechnology or also the social and economic impacts of a technology that, in turn, might cause and adverse health or environmental impact."
The National Research Council is a private, nonprofit institution that provides science and technology advice under a congressional charter. The report, "Animal Biotechnology: Identifying Science Based Concerns," can be read online at: http://www.nap.edu/catalog/10418.html?onpi_topnews082002