Still others are intended to produce drugs. Certain animals are being genetically altered to be used in human transplantations -- for instance, providing cells or tissues or organs that are less likely to be rejected by the human immune system, Lutter said.
"These include islet cells to help diabetics, skin grafts for burn victims, and liver or kidney or heart replacements for the critically ill," he said.
Other genetically engineered traits could help animals resist diseases such as mad cow disease. And some animals are being developed to decrease their environmental impact by decreasing harmful substances in their manure.
Lutter said the U.S. Food, Drug and Cosmetics Act gives the FDA the authority to regulate genetically engineered animals.
"Genetically engineered animals that contain a recombinant DNA segment that is intended to alter the structure or function of the animal are considered to contain a new animal drug," he said. "Genetically engineered animals will, therefore, require premarket approval by FDA prior to their introduction into the marketplace."
Dr. Larisa Rudenko, senior adviser for biotechnology at the FDA's Center for Veterinary Medicine, said the safety of genetically engineered animals intended for use as food will be decided on a case-by-case basis.
"Attention will be paid to particular risks posed by each line of animal, although the basic test will be the same for all animals," Rudenko said during the teleconference. "If the animal is intended to be used for food or feed, we will have to do a full evaluation of food and feed safety. We will also perform an environmental assessment."
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