Don't take a hammer to your new U.S. passport. And don't drill a hole in that credit card or zap it in the microwave.
Experts say these measures - recommended on some extreme Web sites as ways to safeguard privacy and security - are unecessary for people concerned about the growing prevelance of Radio Frequency Identification tags.
The tiny silicon chips are embedded in credit cards, passports and other everyday items and can transmit data on where you go, what you buy and even who you are.
The devices include "smart" car keys, the no-swipe credit card on your key ring, the E-ZPass transponder on your windshield, the prescription bottle in your medicine cabinet, the blouse you buy at the mall and even the soles of your shoes.
The technology - originally designed to track cattle - now speeds up retail transactions, helps authorities confiscate pirated merchandise, identifies company employees, opens electronic locks and tracks shipments of goods through warehouses and stores.
Analysts estimate that RFID tag sales will reach more than $2.36 billion this year - mostly in automotive, security and financial applications.
But as RFID technology spreads and grows cheaper, critics say the tags and the signals they emit are increasingly likely to be abused: by those who would spy on your movements, steal your identity or even target you in a terrorist attack.
The concern has led to some paranoia - and Web sites full of bizarre advice on avoiding RFID snoops. But authorities are beginning to listen to RFID's serious critics.
The U.S. State Department, for example, incorporated metal shielding into the covers of new passports after critics demonstrated how information from the RFID tags embedded in the documents could be read clandestinely from a distance.
Last year, California legislators enacted a law prohibiting employers from forcing their employees to implant RFID tags in their bodies.
They and lawmakers in Wisconsin and other states were spurred into action by an Ohio company that tagged employees who worked with confidential documents - voluntarily, according to news reports.
But the real problem, critics say, is that RFID tracking is virtually invisible and undetectable by its subjects.
