Long study led to U.S. cloned food safety decision

By Maggie Fox, Health and Science Editor

WASHINGTON (Reuters) - Cloned animals may often be born deformed and die young but scientists, who have looked at every aspect of their biology to try to explain why, can find no evidence that it would be dangerous to eat them.

None of the more than 700 studies reviewed in detail showed any evidence to suggest that milk or organ or muscle tissue from cloned animals could harm someone who ate it, the U.S. Food and Drug Administration said in its final report on the subject on Tuesday.

"We have actually done a more in-depth analysis of the meat from cloned animals than has been done ever," said Mark Walton, president of Texas-based farm animal cloning firm ViaGen.

In 2002, a National Academy of Sciences panel said there was no reason to believe that meat or milk from cloned animals may be unsafe. But it said the FDA should do a review, and because of the outpouring of opinions and fears about the subject, the agency extended its review for more than a year.

Cloned calves have died from respiratory, digestive, circulatory, nervous, muscular and skeletal abnormalities, as well as because they had abnormal placentas, the FDA noted.

And researchers have looked at all the possible causes of these abnormalities -- changes in the genes, in other parts of DNA that affect what genes do and the process of cloning itself.

They have looked at whether the surviving animals have unusual levels of hormones such as the stress hormone cortisol or growth hormones. They have looked at whether their milk contains altered levels of fat or fatty acids, and they have fed animal products from clones to mice and other animals to see if there are any health effects.

TRICKING AN EGG

Animals are cloned using somatic cell nuclear transfer -- a process in which an egg cell is hollowed out and the nucleus from an ordinary cell from the animal to be copied is put inside. An electric or chemical charge is used to start the egg growing and dividing as if it had been fertilized by a sperm.

This process itself can cause changes in the development of the embryo, fetus and young animal. Not all the same genes are turned on as are active during normal sexual reproduction, studies have found.

But if the animal survives more than a few months, it appears normal in most ways, the studies indicate.

"As part of the process of evaluating meat and milk from cloned animals, we and USDA (the U.S. Department of Agriculture) looked at a group of cloned animals and we looked at more components of muscle tissue and of meat than normally is looked at," Walton said in a telephone interview.

"This is one of the most rigorous food safety reviews ever conducted," added Dr. Jerome Baker, chief executive officer of the Federation of Animal Science Societies.

As the FDA ruled on Tuesday that food from cloned animals was safe, the Agriculture Department asked the cloning industry to extend a voluntary ban on marketing food from the animals ban during a transition period.

Even so, it is unlikely that people would eat food directly from a cloned animal -- they are more likely to be used as breeding stock, with cloning used to reproduce animals with desired characteristics, animal cloners said.