The idea of electronic implants becoming widespread in humans concerns Dr Katina Michael, an associate professor at the University of Wollongong, who specialises in the socio-ethical implications of emerging technologies.
"RFID microchips are essentially a unique ID embedded in your body, and, as we know, numbers can be stolen and data can be hacked. Bringing one's external computer problems into the human body is fraught with dangers " she says. "They point to an uber-surveillance society that is big brother on the inside looking out. Governments or large corporations would have the ability to track people's actions and movements, categorise them into different socio-economic, political, racial, religious or consumer groups and ultimately even control them."
Michael worries about people being forced or coerced into having one, something she says is likely to have already happened. "It's such a concern that at least nine US states so far have banned forced microchip implants," she says.
In 2007 a company called VeriChip injected 200 Alzheimer's patients, many of them incapacitated, with microchips linked to their healthcare records. The patients were supplied by a Florida nursing home that benefited from the company's sponsorship.
A furore erupted after it was discovered that VeriChip conducted the study without obtaining the required approval from Florida's Institutional Review Board, which oversees the protection of human subjects in research.
Mexico's attorney general and senior members of his staff have been implanted with VeriChips to give them access to secure areas of their headquarters, and the country's military and police are reportedly next in line for chipping.
VeriChip distributor Solusat has also announced an agreement with Mexico's National Foundation for the Investigation of Lost and Kidnapped Children, to promote the microchipping of the country's children.
How the chips could help is uncertain, as they do not have GPS tracking technology.
The VeriChip company has now changed its name under a barrage of negative publicity and has emerged as a developer of what it calls "biological detection systems".
Other companies are also marketing microchip implants, and their researchers are working hard to integrate them with GPS technology. When they succeed, the products are forecast to gain a huge international market.
Opponents of the idea are fighting back. "Technology of this kind is easily abusive of personal privacy," says Lee Tien, of the Electronic Frontier Foundation. "If a kid is trackable, do you want others to be able to track your kid? It's a double-edged sword."