Fish have already been genetically engineered to grow to market size faster, "so that the wild ocean populations will not be subject to such intensive harvest pressure," Dunham said.
Opponents say the practice could unleash unintended consequences by altering the traditional genetic structures of animals.
During the comment period, many consumer groups asked the FDA to require labels identifying food as coming from genetically engineered animals.
However, FDA officials said Thursday that while a genetically engineered animal has to be labeled as such, any food products from that animal do not.
"All genetically engineered animals have to be accompanied by labeling so that they can be distinguished from non-genetically engineered counterparts," Larisa Rudenko, senior advisor for biotechnology in the Center for Veterinary Medicine, said during the teleconference.
"[The] FDA is required to ask for labeling if there is a material difference in the food that comes from these animals, but we are not required by law to ask producers to indicate that food comes from genetically engineered animals," she said.
Genetically engineered food production has been around for a long time. Genetically engineered yeast is used in baking and brewing, and other products from genetically engineered microbes are used in cheese-making. Genetically engineered microbes are also widely used in medicine to produce drugs.
Certain animals are being genetically altered to be used in human transplantations -- for instance, providing cells, tissues or organs that are less likely to be rejected by the human immune system. These include islet cells to help diabetics, skin grafts for burn victims, and liver, kidney or heart replaceme
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