WASHINGTON  The affordability and growing popularity of color laser printers is raising concerns among civil liberties advocates that your privacy may not be worth the paper you're printing on. More manufacturers are outfitting greater numbers of laser printers with technology that leaves microscopic yellow dots on each printed page to identify the printer's serial number — and ultimately, you, says the San Francisco-based Electronic Frontier Foundation, one of the leading watchdogs of electronic privacy. The technology has been around for years, but the declining price of laser printers and the increasing number of models with this feature is causing renewed concerns. The dots, invisible to the naked eye, can be seen using a blue LED light and are used by authorities such as the Secret Service to investigate counterfeit bills made with laser printers, says Lorelei Pagano, director of the Central Bank Counterfeit Deterrence Group. Privacy advocates worry that the little-known technology could ensnare political dissidents, whistle-blowers or anyone who prints materials that authorities want to track. "There's nothing about this technology that limits its application to counterfeit investigations," says Seth Schoen, a computer programmer with the Electronic Frontier Foundation. "Some people who aren't doing anything wrong may have their privacy threatened." Schoen's tests have found the dots produced by 111 color laser printers made by 13 companies including Xerox, Canon, Hewlett-Packard, Epson and Brother. The dots are produced only on laser devices and not ink-jet printers, which are most commonly used at home. But laser printers, which produce more durable images, are becoming increasingly popular as their price has dropped to as low as $300, says Angele Boyd, a vice president of IDC Research. Although laser printers made up only 4% of the 33 million printers sold last year in the USA, their sales have been growing by double digits since 2004, Boyd says. The technology began as laser printers were first produced in the mid-1980s and governments and banks feared an explosion of counterfeiting, Xerox spokesman Bill McKee says. "In many cases, it is a requirement to do business internationally that the printers are equipped with this technology," McKee says. The dots tell authorities the serial number of a printer that made a document. In some cases, it also tells the time and date it was printed, Pagano says. "The Secret Service is the only U.S. body that has the ability to decode the information," she says. Printer makers "cooperate with law enforcement" and will tell authorities where a printer was made and sold, McKee says. The Secret Service uses the dots only to investigate counterfeiting, agency spokesman Ed Donovan says. Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more