"That's pretty disturbing and kind of surprising in that anyone would allow that to occur," said Dr. Stuart Finder, a director at the Center for Biomedical Ethics and Society at Vanderbilt University Medical Center.

"Typically, the idea of using vulnerable people -- children, disabled people, pregnant women, prisoners, a whole variety of categories -- we normally say that's not a good idea," Dr. Finder said.

Dr. Rick Rader, director of the Morton J. Kent Habilitation Center at Orange Grove Center, is advocating cooperation in a study with the maker of the VeriMed implantable device. He arranged meetings Thursday and today for one of the company's physicians with leaders at Orange Grove and Erlanger hospital.

Dr. Rader said VeriChip Corp., the Delray Beach, Fla., company that manufactures the device, has agreed to provide free implants for as many as 100 Orange Grove clients. The clients would be the subjects in the first group study of the application of the device, which normally costs $200, he said.

Dr. Rader and other Orange Grove medical committee members said they thought the implants were a good idea. They said they would have to proceed with care and discuss ethical questions that arise.

The VeriMed device works in much the same way as implantable identification tags for pets, Dr. Richard Seelig, VeriChip vice president for medical applications, said.

He said implantable devices have been used for millions of animals over the past 13 years. The implants for human beings were approved by the Federal Drug Administration in October 2004, he said.

Dr. Seelig told Erlanger and Orange Grove officials Thursday that the implants could keep disabled people safe in case they are lost or injured and cannot identify themselves to emergency workers or doctors.

"What we're trying to do is level the playing field," he said. "If you and I can give this information, why can't they?"

Carol Westlake, executive director of the Tennessee Disability Coalition, said the idea of implants is "troubling."

"The history of abuse of people with mental retardation requires us to be extraordinarily cautious that we don't let those things happen again," she said.

Ms. Westlake and Dr. Finder said it would be less problematic to do a group study of adults who are able to give unambiguous informed consent.

However, Dr. Rader said that not using the implants to benefit and protect the disabled would be a disservice to his clients, would deny their personhood and abridge their right to participate in society.

"The advocates would be on my case if we weren't doing this," he said.

Dr. Seelig said the plan would require participation of area medical facilities, whose personnel would require training to scan for the chips and find medical information once a patient's identification number is found.

He said VeriChip would provide equipment and training to hospitals and other medical facilities at no cost.

Dr. Seelig spoke to Erlanger physicians at the hospital Thursday morning, but none of the physicians there asked about potential ethical implications in using the microchips in vulnerable populations.

A meeting with the hospital's institutional review board scheduled for Thursday fell through when none of the members showed up, Erlanger spokeswoman Jan Powell said.