No longer a science-fiction fantasy, radio frequency identification chips are on the market and available for implantation in the human body.

While society begins to weigh the medical benefits of immediately being able to identify a person from the signals emitted by his or her RFID chip against the costs in personal privacy, a doctor has tested the device on himself and chronicled his experience in the July 28 issue of the New England Journal of Medicine.

"I felt it important that somebody try this new technology," Dr. John Halamka told United Press International. Halamka is chief information officer at the CareGroup Healthcare System and Harvard Medical School, and an emergency physician at the Beth Israel Deaconess Medical Center in Boston.

Now, when someone runs a RFID scanner over the back of Halamka's right arm, a 16-digit number - his medical identifier - appears on the scanner's screen. When typed into a secure computer system, the number provides information about Halamka's identity and the name of the primary-care physician to contact for his medical history.

The technology was approved by the Food and Drug Administration in November 2004. Halamka got his RFID chip implanted Dec. 22.

"It was a five-minute office procedure," he said.

An orthopedist colleague at Beth Israel Deaconess loaded the rice-grain-sized chip into a syringe about the size of a knitting needle and injected it into Halamka's arm, numbed with a local anesthetic.

The risks of infection and pain that arise whenever the skin is punctured apply to the implantation of RFID chips as well, Halamka said, although he experienced neither. He did not name any other possible side effects from the chips.

There is no risk of an RFID chip moving inside the body, because muscle tissue holds it in place. There also is no risk of allergic reaction to the chip, because it is encased in an unreactive medical-grade glass coating.

Halamka said he does not feel his chip, even when using his arm muscles in strenuous activities such as mountain climbing.

The type of chip in Halamka's arm works by emitting a signal when activated by a scanner that comes within six inches of the device.

Sanjay Sarma, associate professor of mechanical engineering and co-founder of the Auto-ID Center at the Massachusetts Institute of Technology, said the necessary radio emissions are at a very, very low power and are not dangerous to the human body.

"The power simply causes infinitesimal and imperceptible warming in the neighboring tissue," Sarma told UPI in an e-mail. "This is what happens every time we use a cell phone, for example. The amount of exposure is likely to be extremely limited. In any case, the (Federal Communications Commission) regulates the power, so that the exposure is well within safe limits."

Halamka estimated about 1,000 people have received the chips, including about 200 in Mexico whose chips contain security-clearance information. The chips are similar to those currently operating in millions of livestock animals, although they operate at a slightly different frequency.

"The technology's been around about a decade," Halamka said. "The application in humans is new."

The industry-standard location for RFID chips is in the back of the right arm between the elbow and the shoulder, Halamka said. At Beth Israel Deaconess, every unresponsive patient brought into the hospital gets his or her arm scanned. The hospital gets one or two unresponsive patients per day, although he said it has not yet treated a tagged unresponsive patient. He said so far only a few hospitals, most of them university or teaching hospitals, possess RFID scanning equipment; according to his report, readers cost $650 and chips cost $200, with variable implantation costs.

The introduction of RFID technology is highly compatible with the recent push to put medical records on the Internet. At this point, Halamka said, about 25 percent of U.S. medical records are available online, although legislation by the Bush administration proposes to bring that figure to 100 percent within 10 years.

One drawback of the technology is the medical identifiers are not encrypted and therefore their information could be intercepted by unauthorized scanners. For example, a scanner at a retail store could note that a customer bought a fountain pen and, on his next visit to the store, alert him via an electronic bulletin board that ink for his pen was on sale.

Halamka acknowledged this could prove troubling to some people.

"To me, privacy is a function of an individual's right to confidentiality," Halamka said. "Some people may not want it disclosed that they were at a certain location or bought a certain product."

Bill Scannell, a privacy activist in Washington, compared medical identifier-containing RFID chips to the tattooing of Holocaust victims at concentration camps.

"I think the early to mid-part of the 20th century showed us that giving people numbers and attaching them to their bodies ... is kind of a bad idea," Scannell told UPI.

He said although he respects the right of individuals to accept RFID chips if they choose, he is concerned about the possibility of mandatory RFID implantation in the future.

"The information that is on that chip is freely available to anyone," Scannell said. "It's like playing Marco Polo in the pool. ... You can have information taken from you without your knowledge."

Others question the necessity of the chips.

"I am not a huge fan of RFID tags inside humans except in extreme scenarios like in defense or in hospitals," Sarma wrote. "Even in those cases, a bracelet might do the trick. I say this not because of any ill effects of RFID tags, but simply because there might be simpler, non-invasive ways to do this. For example, a dog tag or tattooed social security number provide similar benefits."

Halamka acknowledged that RFID chips may not be for everyone, due to individual philosophical and ethical choices, but he said there are numerous uses for the chips. He said that as an emergency-medicine resident, caring for patients who were unable to communicate and carried no identification was a difficult, anxiety-inducing experience.

RFID chips would relieve doctors of having to spend hours searching for the identities of unknown patients and the confusion over unknown patients' treatment preferences, he said. This would make RFID chips ideal for people who engage in extreme sports and do not carry their wallets, or for people with medical conditions that make them unable to communicate - although Halamka said the latter situation poses ethical dilemmas involving the issue of patient consent.

RFID chips can help doctors avoid errors with medications and medical procedures - currently a major problem in hospitals.

"There's an opportunity for us to close the loop and really reduce errors," Halamka said. For instance, RFID chips could determine whether penicillin-containing medications were in the same room as a penicillin-allergic patient and alert medical staff to the problem.

"The advantage is knowing who people are and knowing where they are and making good decisions based on that," Halamka said.