Under-skin ID tags generate concerns

This technology is designed to enable various health care professionals to obtain patient information such as X-rays and medical histories from a database securely and more quickly. The system will also use antennas to track individuals as they walk about the hospital and send alerts if a patient begins to collapse. Other pilot systems are being tested specifically to monitor patients with Alzheimer's disease.

As such tagging systems become more widely known, some industries that hadn't been expected to use the technology are considering innovative applications of it. A South Carolina firearms maker, FN Manufacturing, is evaluating the technology for use in "smart guns" equipped with grip sensors that would allow only their owners to use them.

In a less violent but practical application, Ray Hogan of Princeton University's alumni association has contemplated distributing RFID bracelets among meeting attendees to track attendance at events that have multiple components. The technology would let organisers see which programmes attendees find most valuable by virtue of how long they stay. Like others, however, Hogan says privacy issues may well keep the idea from becoming a reality.

When such technologies are employed, they can be even more effective if implanted in the body. Supporters and critics both say RFID tags under the skin would invariably increase the volume and quality of personal data, with the benefit of, at the very least, reducing the margin of error for misidentification in the event of a disaster.

The problem, detractors say, is that the vast quantities of accumulated data would be vulnerable to theft and abuse. They cite historical practices of retail establishments, which for years have listened in on customer conversations and viewed consumer behaviour on remote cameras to improve sales. Supermarkets routinely collect data about individual shoppers' purchases and buying habits through "loyalty programs", along with credit card and electronic banking transactions.

Even random individuals could spy on those with tags, because today's RFID technologies do not yet have the processing power to encrypt information. "I don't see how you can get enough power into those things" to encrypt data, said Whitfield Diffie, a fellow and security expert at Sun Microsystems.

Some consumers have described scenarios in which a hacker could extract a person's identification number with an RFID reader, create a chip with the same number and then impersonate them. But even if such chip forgery were possible, alerts would probably be sounded as soon as a system detected that the same person was in two different places at once.

Still, implanting RFID chips could vastly increase the potential for police surveillance of ordinary citizens. Conceivably, every wall socket could become an RFID reader that feeds into a government database.

Critics contend that if tagging gets out of control, the day will eventually come when the cops will be able to trace junk thrown in a public trash can back to the person who tossed it.

"Do you want the people in power to have that much power?" Albrecht asked rhetorically. "The infrastructure obstacle has been overcome. It is called electricity and the Internet."