WASHINGTON -- The possibility of certain genetically engineered fish and other animals escaping and potentially introducing engineered genes into wild populations tops the list of concerns associated with advances in animal biotechnology, says a new report from the National Academies' National Research Council. On the other hand, no evidence yet exists that products from cloned livestock are unsafe for human consumption, although 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 report was requested by the Food and Drug Administration as it prepares to rule on the safety of certain animal-biotechnology products, particularly cloned cattle. The committee was asked only to identify science-based concerns; it was not asked to identify potential benefits from animal biotechnology or to make policy recommendations.

"As is the case with any new technology, it is almost impossible to state that there is no concern, and in certain areas of animal biotechnology we did identify some legitimate ones," said committee chair John G. Vandenbergh, professor of zoology, North Carolina State University, Raleigh. "By identifying these concerns, we hope we can help this technology be applied as safely as possible without denying the public its potential benefits."

The committee said the greatest concern is the ability of certain genetically engineered organisms to escape and reproduce in the natural environment. Genetically engineered insects, shellfish, fish, and other animals that can easily escape, that are highly mobile, and that become feral easily are of particular concern, especially if they are more successful at reproduction than their natural counterparts. For example, it is possible 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.

By creating transgenic animals with genes from another species, or by removing or "turning off" genes, animals can be produced to grow bigger and more rapidly, or 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. And 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.

In transgenic animals developed for human consumption, there is a low probability that a few new proteins expressed when genes are inserted from another species may trigger allergic or hypersensitive reactions in a small, but unknown, percentage of people. The potential for allergenicity is difficult to gauge, however, since it can only be detected once a person is exposed and experiences a reaction. While a reaction will be recognizable, as it is with well-known allergens like peanuts and shellfish, the uncertainty surrounding new proteins and potential impact on consumers who may be allergic is serious enough to elicit a moderate level of concern, according to the committee.

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 the committee said there are grounds for concern that adequate controls be in place to ensure restrictions on the use of carcasses from such animals. In at least one instance, meat from the carcasses of such animals was used to make a food product.

The applications of biotechnology may someday reduce the number of animals needed for food and fiber production, but they also can have adverse effects on the welfare of animals, 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. There is also a 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.

Although the committee was not asked to make any policy recommendations, it suggested that the current regulatory framework may not be adequate given that the responsibilities of federal agencies for regulating animal biotechnology are unclear in some respects.

The study was sponsored by the Food and Drug Administration. The National Research Council is the principal operating arm of the National Academy of Sciences and the National Academy of Engineering. It is a private, nonprofit institution that provides science and technology advice under a congressional charter. A committee roster follows.

Read the full text of Animal Biotechnology: Science-Based Concerns for free on the Web, as well as more than 1,800 other publications from the National Academies. Printed copies are available for purchase from the National Academy Press Web site or by calling (202) 334-3313 or 1-800-624-6242.

[This news release and the report are available at http://national-academies.org]