The path from the lab to the marketplace for genetically modified cows, pigs and chickens has been clearly spelled out for the first time.

On September 18, the U.S. Food and Drug Administration released a draft of regulations for approving engineered animals for commercial use. The draft is freely available and open for public comment until November 18.

The FDA’s announcement does not mark any major changes to its practices for approving genetically engineered animals for commercial use. But releasing the draft does signal that the FDA will continue to use the relatively stringent authority granted by the Federal Food, Drug, and Cosmetic Act instead of more lenient laws — a choice that some in the industry had begun to doubt.

“There’s nothing in this guidance that’s really new,” says FDA spokeswoman Siobhan DeLancey. “It’s how we’ve been regulating [genetically engineered] animals all along; we’re just making it official that this is how we intend to do it.”

Scientists have been using modified animals in laboratories for some time. Experiments have yielded hypoallergenic pets; poultry and livestock that produce healthier foods; “pharm” animals that make drugs, such as insulin, for people; pigs for safe organ transplants; and disease-resistant animals that simplify livestock management.

But the only engineered animal to reach consumers thus far is a pet fish that glows in the dark.

Genetic modifications to animals must be approved by the FDA in the same way that new drugs for the animals must be. And companies that create altered animals for food or for producing food bear the responsibility to demonstrate that the food is safe to eat. The draft guidelines also mandate that candidate animals undergo a standard environmental impact assessment before approval.

But the guidelines also leave room for the FDA to decide when to waive enforcement of the regulations for certain modified animals, such as laboratory mice used only in experiments.

“That’s the $64,000 question,” comments Michael Taylor, a public health policy expert at George Washington University in Washington, D.C. Taylor worked for the FDA in the 1990s and later sat on a commission that advised the FDA on the scientific risks of genetically altered animals. “That’s the thing to focus in on, the extent of this exception to premarket approval.”

FDA officials did say that animals intended for food would never be exempt from the approval process. But exemptions for other engineered animals will be considered case-by-case in a “risk-based decision,” said Larisa Rudenko, senior adviser for biotechnology at the FDA’s Center for Veterinary Medicine during a teleconference with reporters on September 18.

In 2003, the FDA decided to waive regulation of a genetically engineered, glow-in-the-dark zebra fish that was subsequently sold as a pet. The agency deemed that the fish posed no greater environmental risk than unmodified pet zebra fish. “And, you know, most companion animals are not consumed for food in the United States,” Rudenko said during the teleconference.

The rules don’t apply to cloned animals that are otherwise not genetically modified.