In 2004 the FDA approved an implantable, rice grain sized microchip for use in humans. The tiny subcutaneous RFID chip, made by a company called VeriChip, is being marketed as a lifesaving device. If you're brought to an emergency room unconscious, a scanner in the hospital doorway will read your chip's unique ID. That will unlock your medical records from a database, allowing doctors to learn about your penicillin allergy or your pacemaker.

The tiny, passive RFID devices are injected under the hide. They do not contain the medical data in question, but instead store a unique ID number that is used to access records on a remote server maintained by Applied Digital, using a handheld reader.

VeriChip's biggest human-chip market is Mexico. Eighteen members of the attorney general's staff were implanted with a chip in order to control access to a new government facility.* Building security isn't the biggest part of VeriChip's south-of-the-border sales pitch, though. Mexico's kidnapping wave the country's 3,000 abductions a year are second only to Colombia worldwide has led VeriChip to partner with the National Foundation for the Investigation of Lost and Kidnapped Children. So far, 1,000 Mexican citizens have voluntarily had RFID chips implanted.

You shouldn't trust RFID to stop a kidnapping or to save your life in an emergency. Perhaps a more realistic suggestion is to use RFID implants to replace the tracking bracelets now imposed upon those who a) aren't trusted to be in the right place at the right time; and b) aren't given much of a choice: kids (at theme parks like Fort Lauderdale's Wannado City and Legoland in Denmark), the elderly, and prisoners. Though injection is unpleasant to think about, subdermal devices are far harder to remove and, thus, far more reliable than an external bracelet. And what about the lighter side of chip injection? Patrons of Barcelona's Baja Beach Club now pay for drinks via a system that links their VeriChip implants to their credit cards.

These small electronic chips approved by the FDA for implanting beneath human skin have been linked to cancer in laboratory animals, according to a research review conducted by the Associated Press.

The radio frequency identification (RFID) chips are made by VeriChip Corp. They are designed to carry a serial number, which can be read when scanned by anyone with an RFID sensor. Medical workers can then use that number to access a patient's medical history from a web site maintained by the corporation, provided they have paid the annual access fee.

The chips, which are approximately twice the size of a grain of rice, were approved by the FDA for human implantation in 2005. But the Associated Press has revealed that as early as 1996, researchers had uncovered a link between the devices and cancer. Rodents implanted with the chips were found to develop malignant tumors beneath the skin, usually surrounding the devices. The rates were high enough -- as high as 10 percent of animals implanted, in a 1998 study -- to raise warning bells with the researchers, who reported their concern in peer-reviewed journals.

None of the studies were looking for carcinogenic effects from the RFID tags, but in each case the researchers ruled out other possible causes. Although there was no non-implanted control group in many of the studies, the evidence is strong enough to convince many researchers that more research is needed before any more human implantation takes place.

There's no way in the world, having read this information, that I would have one of those chips implanted in my skin, or in one of my family members, said Dr. Robert Benezra, head of the Cancer Biology Genetics Program at the Memorial Sloan-Kettering Cancer Center in New York.

This research review clearly shows cause of concern over the mass microchipping of our population for medical purposes," explained consumer health advocate Mike Adams. "Intelligent, reasonable people will naturally reject such chip implants, which is exactly why the company is targeting individuals suffering from cognitive decline, such as Alzheimer's patients," Adams added.

So far, 2,000 people have been implanted with VeriChip's RFID chips. The company has identified is target market in the United States as 45 million people, starting with Alzheimer's and diabetes patients.

Lastly, these RFID implanting has become a hot topic in the past few years. Early on, the dangers of implants at least in terms of privacy and security appear to be outweighing the benefits. The biggest fear is that the tiny rice-sized implants may someday become mandatory and would then be used as some sort of Big Brother type device to keep tabs on private citizens. Some states, such as Wisconsin, have even gone so far as to pass legislation banning any such mandatory chip implantation. Preemptory? Perhaps, but concerns about RFID implants are not unfounded. Implants can be read by anyone with access to a RFID scanner, and hackers have shown that the chips are not as secure as had been previously thought.