In releasing its 968-page final risk assessment on the safety of cloning technology, the FDA asked producers to continue keeping cloned cattle, pigs and goats out of the food supply during a transition period of unspecified length.
"Meat and milk from clones of cattle, swine and goats and their offspring are as safe to eat as food from conventionally bred animals," said Randall Lutter, the FDA's deputy commissioner for policy.
Government scientists said they did not have enough information on cloned sheep or other species to rule that they were safe to eat.
Initially, only a small amount of steaks, pork and dairy products derived from clones will become available in grocery stores, industry executives said. But over the next three to five years -- after ranchers have time to clone their most prized animals and those clones are able to breed -- the products will become routine on store shelves, they said.
The decision, at least seven years in the making, was based on hundreds of studies conducted around the world that found that meat and milk from clones is biologically indistinguishable from meat and milk sold to the public today.
Critics remain unconvinced. "Just because something was created in a lab doesn't mean we should have to eat it," said Sen. Barbara A. Mikulski (D-Md.), who had pressed the FDA to conduct further studies on the safety of clones and will now push for mandatory labeling. "If we discover a problem with cloned food after it is in our food supply and it's not labeled, the FDA won't be able to recall it."
The FDA said it would continue to monitor the safety of cloned food and would adjust its policy if necessary.
Consumer advocates also expressed outrage. "FDA's action has placed the interests of a handful of biotech firms above those of the public they are charged with protecting," said Andrew Kimbrell, executive director of the nonprofit Center for Food Safety in Washington.
The risk assessment said that "cloning raises many ethical and economic concerns" that are important to the public but that the FDA's task was to focus on the science.
Even with the FDA's endorsement, producers face an uphill battle persuading consumers to accept the new technology.
A survey last year by the International Food Information Council, which is supported by the food, beverage and agricultural industries, found that 22% of U.S. consumers had a favorable view of animal cloning, compared with 50% who were opposed. If deemed safe by the FDA, support for using cloned animals as food rose to 46% -- a substantial increase, but still a minority of consumers.
Cloning advocates acknowledge that the technology has a "yuck factor" that has been difficult to shake.
"The entertainment industry has used the word 'clone' in a negative context," said Jerry Baker, chief executive of the Federation of Animal Science Societies in Savoy, Ill. "That's a hard one for us to overcome, but we have to continue to try."
Scientists frequently point out that clones are not genetic mutants but identical twins of naturally produced animals -- just born at a different time.
To make a clone, scientists remove the DNA from the nucleus of a normal egg and replace it with DNA from a prized animal. A tiny electric shock induces the egg to grow into a copy of the original animal. No new genes are introduced or modified in the process.
"We're not out to create some kind of abnormal individual," Baker said.
Producers, like Limousin cattle rancher Larry Coleman of Charlo, Mont., said they simply wanted to extend the breeding capabilities of their most superior animals.