This is the VOA Special English Technology Report.

Lawmakers in the United States have expanded an investigation into the use of location-tracking systems on mobile devices.

The action follows recent reports about the storing of information on the Apple iPhone, iPad and iTouch. Questions have also been raised about Google Android devices. Some people consider location tracking to be a threat to personal privacy and security.

Allan Friedman is the research director for technology and innovation at the Brookings Institution in Washington. He says all wireless companies do some amount of location tracking as part of their networks. Mr. Friedman says this information is usually stored by the companies, not the devices, and there are laws to protect it.

ALLAN FRIEDMAN: "Law enforcement, for example, has to have a fairly high standard before it can access that data. And the phone company is also prohibited from selling that information."

Congress discussed the issue of mobile privacy last year. Now, two researchers reported last month that location tracking information is being stored directly on Apple devices. They said Apple's newest operating systems gather global positioning system and timestamp information.

The information is stored on the device in a file that is also uploaded to any computer that the device is connected to. The researchers say the information is available to anyone who has access to the device or computer.

Allan Friedman says this raises additional concerns.

ALLAN FRIEDMAN: "There's the idea that because it's on my phone and on my computer, rogue applications that I pay for or that I'm tricked into downloading may be able to access this data and somehow misuse it."

Apple, in a statement, says it is "not tracking the location of your iPhone." The company says it is simply keeping a database of Wi-Fi hotspots and cell phone towers near the user's location. It says this information is meant to help the iPhone quickly find its location when needed.

Last week, leaders of the House Energy and Commerce Committee sent letters to some of the leading mobile device developers. These include Apple and Google. The letters asked for more information about their location tracking systems.

Allan Friedman calls this an important start to strengthening privacy laws.

ALLAN FRIEDMAN: There aren't strong controls over things like location data. We need to understand who is getting my location information, what are they doing with it, how long are they keeping it. And perhaps the most important question is, is my location data tied with other facts about me?"

A new Senate subcommittee on privacy, technology and the law plans to hold a hearing on May 10th about protecting mobile privacy.

And that's the VOA Special English Technology Report, written by June Simms. I'm Steve Ember.

Related stories

Ex-governor Ventura sues over body scans

Mobile phones may soon test for STIs and blood pressure

英政府擬監控社交網站用戶信息

代表建議對個人信息立法保護

（來源：VOA 編輯：崔旭燕）