Putting Google and Apple once again under harsh scrutiny of their privacy practices, a senior senator from New York called on the Federal Trade Commission on Sunday to look into apps that "are leaking user data."

Sen. Charles Schumer was reacting to news that both Google's Android operating system and Apple's iOS allow applications that send photos to third-party servers. In a letter to FTC Chairman Jon Leibowitz, Schumer also noted reports of apps that allow location data and address books to be "copied in their entirety and used for marketing or other purposes."

"These uses go well beyond what a reasonable user understands himself to be consenting to when he allows an app to access data on the phone for purposes of the app's functionality," Schumer wrote.

The third-ranking Democrat in the Senate, Schumer is known for his weekly Sunday news conferences, usually on consumer protection issues.

Hands Full

The FTC already has its hands full policing the privacy practices of technology giants. It called Google on the carpet for opting Gmail users in to a now-failed social network, Buzz, without asking, and took on Facebook for making misleading promises about what information the world's biggest social network shared.

Apple, for its part, has faced critics on privacy issues before. Last year, it was discovered that iPads and iPhones track and keep the location data of users. The company blamed the data collection on a system bug.

On Feb. 28, The New York Times, based on information from developers, reported that allowing some apps to access information on an iPhone, iPad or iPod Touch allowed them to "copy the user's entire photo library, without any further notification or warning."

"It is my understanding that many of these uses violate the terms of service of the Apple and Android platforms through which the apps are marketed and sold," Schumer wrote to Leibowitz. "However, it is not clear whether or how those terms of service are being enforced and monitored. In fact, the abuses of apps have only come to light as a result of the work of intrepid independent researchers and technologists. As a result, it is users and their privacy who suffer."

What They Don't Know Can Hurt Them

As the ease of using smartphones conceals the complexity and sophistication of their design and capabilities, users need to be protected, said technology analyst Jeff Kagan.

"Today, what smart phones can do has gotten way ahead of what most users understand," he said. "In fact it has gotten way ahead of all laws to protect consumers. That's why the effort of Sen. Schumer may be necessary. If the industry doesn't want to police itself, then it has to be policed."

Schumer's letter was hailed by the Future of Privacy Forum, a public policy advocacy group that aims to find common ground between consumers and business.

"[He] is exactly right in that the platforms need to get this right before consumers start to worry about downloading apps for fear of data theft," said the forum's co-chairman, Jules Polonetsky. "The FTC has already warned app developers that not disclosing key information could be the subject of enforcement action, and the California attorney general has signed an agreement with Google and Apple that is focused on app privacy practices."

Polonetsky was a legislative aide to Schumer from 1992 to 1994.

The senator's letter is the second from Congress to the FTC in a few weeks. Last month, Reps. Edward Markey, D-Mass., Joe Barton, R-Texas, and Cliff Stearns, R-Fla., asked Liebowitz to look into Google's use of a code that reportedly bypasses browser privacy settings for Apple's Safari.