Meat counters and dairy cases are likely to become the latest battlegrounds for the use of biotechnology down on the farm.
Thursday, the US government released a draft report concluding that food from cloned cattle, pigs, and other livestock is as safe to eat as food products from conventionally bred animals. The safety assessment paves the way for ranchers to use clones for their breeding stock, using cloning techniques similar to those that created Dolly the sheep in 1996.
The decision is not likely to create a flood of cloned livestock in the short term, several analysts say. The assessment, from the US Food and Drug Administration's Center for Veterinary Medicine, must still endure 60 days of public comment. And the FDA still must weigh issues, such as whether to label meat products from the offspring of cloned animals or track the clones themselves if they move into the food system after their usefulness as breeding stock ends. It may take a year or two after the comment period ends for breeders to start using clones.
Still, the assessment represents a significant step toward approving a technology that several specialists say will lead to more consistent, and higher quality meat and dairy products. And it is galvanizing opposition from consumer and food-safety groups. They hold that the health-risk studies fall short of what's needed to ensure that such products are safe.
"The FDA has taken a very long time to analyze this in a way that is still incomplete," says Jaydee Hanson, a policy analyst with the Center for Food Safety, a biotech watchdog group in Washington. The group has filed a petition with the FDA asking it to conduct safety studies for food products from cloned livestock as rigorously as it does studies for animal-derived drugs that humans use.
The current concern over cloned livestock arises from the technique used to produce them. For years, breeders increased the number of their prized animals by dividing early embryos, then implanting them into a mother to produce artificial twins.
But the results are still hit-and-miss, says Michael Pariza, director of the Food Research Institute at the University of Wisconsin at Madison. And while breeders also currently use artificial insemination and fertilize eggs in a test tube, the bull providing sperm for the procedure has a finite lifespan. But with cloning, breeders can store the bull's DNA for use long after he has been put out to pasture.
When researchers in Scotland cloned the sheep Dolly in 1996, Dr. Pariza continues, they implanted genetic material from an adult into an egg nucleus, then inserted the altered egg into a surrogate mother. Breeders recognized that this approach would eliminate the uncertainty. "You now have a new cow with a known pedigree," he says. And by storing samples of an animal's DNA, the line can be cloned repeatedly.
But the approach has its drawbacks. The technique used to derive the clones is inefficient and often leads to stillborn or deformed offspring. This prompts opponents to call the process unethical. Others wonder if Dolly-like cloning introduces subtle, potentially harmful changes that current testing techniques can't find.
Proponents hold that cloning is no more dangerous to the parent or offspring than the "test-tube calf" approaches breeders currently use. And so far, a range of studies – from chemical assays of cloned meat and milk to tests where lab rats consume meat and milk from clones – indicate that food from cloned animals is as safe as food from noncloned animals. Several of these studies appear in the Jan. 1, 2007, issue of the journal Theriogenology, which focuses on animal reproduction.
"These are edible animals to begin with – they are not going to suddenly start producing toxins," Pariza says.
Whether such results satisfy the public is an open question. Some dairy groups and meat producers have reportedly expressed private concerns that they will loose business if cloned meats and milk work their way into burgers and shakes.
Proponents point to polls showing that a majority of consumers are willing to buy or consider buying food from cloned animals.
Opponents turn to other polls that suggest a general public revulsion at the idea.
Some specialists say the FDA needs to improve its ability to detect and assess the impact of any unintended changes that could render food from cloned animals unfit to eat.
The National Academy of Sciences has recommended that the FDA set up a public database of compounds in foods derived from animal clones. It adds that the government should set up a way to identify and track products from cloned animals as they move from the field to the market.