Study: Someone is watching you

That means roughly one of every three of the 40 million employees using e-mail or the Internet on the job are monitored, the Privacy Foundation says in a statement announcing the report, to be released Monday. Worldwide, 100 million workers, or about 27 percent, are monitored, the nonprofit group said.

The study was based on financial reports from companies that sell software that helps employers monitor online activities. The most popular software surveillance packages are Websense for tracking Internet use and MIMEsweeper for scrutinizing e-mail, the foundation said.

Companies that monitor employees' online activities include 20th Century Fox, Glaxo Wellcome, Nike, Duracell, Barclays, Marriott, Texaco, American Express, Premera Blue Cross and Zenith Electronics. Government agencies include the U.S. Army, the Small Business Administration, the National Park Service and the City of Boston.

The foundation estimates worldwide sales of employee surveillance software at $140 million per year--roughly $5.25 a year per monitored employee.

The dropping cost of surveillance software is the primary reason for its increasingly widespread use, the foundation said. "Employee monitoring, as measured by the sales of surveillance software, has increased at least twice as fast as the number of U.S. employees with Internet access in the past few years," the foundation said.

Though companies often cite liability concern among the reasons for using such software, such a process might backfire, the study said. "By creating and storing a detailed audit trail of employee activities, organizations may be inadvertently stockpiling large amounts of potential evidence that could be used against them in future litigation," the foundation said in the statement.

The study was part of the group's Workplace Surveillance Project.