The FDA published proposed detailed guidelines that producers of genetically engineered animals would have to follow to determine whether there are any risks to humans, the environment and the animals themselves.
The guidelines bring the decades-old technology of genetic engineering for animals one step closer to the market.
Genetically modified cattle, pigs, fish and goats are being produced for a variety of uses. Some produce pharmaceuticals in their milk or blood. Others are resistant to diseases such as mad cow or produce healthier meat or milk.
"Many kinds of genetically engineered animals are in development, although none has yet been approved by the agency for marketing," FDA Deputy Commissioner Randall Lutter said.
It was important to formalize procedures the FDA uses to regulate genetically engineered animals, Lutter said, "because the technology has evolved to a point where commercialization of these animals is no longer over the horizon."
The agency is inviting public comment on its proposals until November 18 and could modify them before they become final.
Consumer groups called the FDA's action a good first step, but said the guidelines fail to answer several important questions.
One concern is the approval process, which would be secretive to protect companies' proprietary interests.
"It's unclear whether FDA has the authority and expertise to address the full range of risks," said Gregory Jaffe of the Center for Science in the Public Interest.
Foods produced from some bioengineered animals will not have to be labeled, the FDA said, also drawing some ire.
"It is incomprehensible to us that FDA does not view these animals as different from their conventional counterparts," said Jean Halloran, director of food policy initiatives at Consumers Union.
"Consumers have a right to know if the ham, bacon or pork chops they are buying come from pigs that have been engineered with mouse genes."
But the FDA said labeling would be required if there is a significant change in the food. For example, pork from pigs engineered to produce meat with higher levels of omega-3 fatty acids would need a label.
Producers will be required to describe what DNA they have inserted into the animal, and how it behaves in the animal, the impact on the animal's health, and show the product is not different from traditional food.Companies also would have to tell the FDA how they would track the animals and dispose of them when they die. If there is a high risk, the FDA might require the animals to be sterilized.
The FDA said it has the authority to regulate genetically engineered animals through the Federal Food, Drug and Cosmetic Act. The measure identifies a drug as anything that changes the "structure or function" of the person or animal.