Me and my shadow: the prospect of human cloning raises environmental and ethical issues.

In the recent film Multiplicity, the condo contractor played by Michael Keaton discovers that having a clone of himself around to help with the heavy lifting is not quite the trouble-free experience he had imagined. So too, in real life, is the prospect of human cloning rather daunting.

While human cloning has been the stuff of science fiction for centuries, the possibility that it actually could happen is of much more recent vintage. In July of 1996, Dr. Ian Wilmut of the Roslin Institute in Edinburgh, Scotland became the first scientist to successfully clone an adult mammal. (The cloning of embryos has been going on much longer, with Dr. John Gurdon cloning an adult South African tree frog in 1962.)

It took Dr. Wilmut 277 tries to create the lamb Dolly from the merger of a six-year-old sheep's mammary cell with a prepared sheep's egg. Since Dolly met the press, a number of scientists have come forward to acknowledge that they, too, are experimenting with the cloning of mammals. Their interest is not purely scientific. Wilmut's Roslin Industries, for example, is in partnership with the biotechnology company PPI, Therapeutics, whose aim is to sell cancer- and cystic fibrosis-fighting human proteins collected from genetically engineered animal "hosts."

A U.S. company, Alexion Pharmaceuticals of New Haven, Connecticut, is working to develop a "super" pig whose organs (genetically coated with human proteins to minimize cross-species rejection) would interchange with those of humans. But this raises the specter of animal viruses like "mad cow" disease (bovine spongiform encephalopathy) crossing over to humans along with the transplants. "One of the things people have learned is that it's not wise to cross such boundaries," says Dr. Margaret Mellon, a scientist with the Union of Concerned Scientists (UCS) who serves on its panel investigating the ecological risks of genetically engineered products. Despite the warnings, there are more than 190 genetically engineered animals awaiting patents by researchers and corporations.

Is it a short step or a giant leap from a cloned sheep to a cloned human being? Few scientists doubt that human cloning is possible. "It seems very likely that it would work with humans," says Brigid Hogan, a biologist at Vanderbilt University. Nature magazine, which first published Dr. Wilmut's work, estimates that adult human cloning is likely to be achievable "in one to 10 years."

A human clone will never be a perfect copy, says Dr. Glenn McGee, an assistant professor in the Center for Bioethics at the University of Pennsylvania and the author of The Perfect Baby. Parents who would consider cloning a dead child, for example, should realize "that it would not be the same child, though it would look very similar. Environmental factors shape who we are."

The prospect of human cloning has obvious ethical dimensions, and it was for that reason that President Clinton (who banned the use of government funds for human cloning research last March) asked a federal panel to look into the matter and make recommendations. Dr. Alta Charo, a professor of law and medical ethics at the University of Wisconsin, sits on that body, the National Bioethics Advisory Commission (NBAC). Dr. Charo notes that only 10 states have laws that regulate human bioengineering, and that all of them only "address the forming of embryos from the union of egg and sperm."

Taking note of the vast media interest in the subject, Dr. Charo cautions, "The research is still so enormously preliminary. We've yet to see Dr. Wilmut's success replicated in a single sheep, let alone in people."

Also on the federal panel is Dr. Thomas Murray, director of the Center for Biomedical Ethics at the Case Western Reserve School of Medicine in Cleveland. He says that the panel has talked to a group of theologians representing the Protestant, Catholic, Jewish and Islamic faiths. "None of them said it was a wonderful thing," Dr. Murray says, "and many are concerned that it's an exercise in human hubris."

Hubris is putting it mildly, says bioengineering critic Jeremy Rifkin. "This is the most radical experiment conducted against human nature in history," he says. "We have here a new eugenics movement that goes beyond Hitler."

Even without the human dimension, cloning presents ethical dilemmas. Dr. Jane Rissler, a Washington-based UCS senior staff scientist in agriculture and biotechology, is concerned that cloning will further weaken the already imperiled genetic diversity of agricultural crops and animal species. "Both crops and livestock have become very uniform and much more vulnerable to disease," she says.

But while cloning poses a threat to some plants and animals, it could also be used to save others, says Dr. Betsy Dresser of The Audubon Center for the Research of Endangered Species in New Orleans. Dr. Dresser, who headed the team that created the first test tube gorilla at the Cincinnati Zoo in 1995, says that cloning could help preserve endangered animals. "Theoretically, what worked with Dolly could work with any mammal," she says. For example, a wild-caught orangutan could be cloned and his "copies" used to enrich the genetic diversity, in a number of zoo populations.

While cloning animals has received tentative public approval (according to ABC News, 53 percent of Americans approve of cloning animals for medical research) human xeroxing is decidedly less popular. A full 87 percent oppose cloning humans, and 93 percent don't want to be cloned themselves. CONTACT: Union of Concerned Scientists, 26 Church Street, Cambridge, MA 02238/[phone].