European data protection officials are expanding their examination of the impact search engines have on privacy, after initially targeting Google last month.
The EU’s Article 29 Working Group decided to request information from Google's rivals amid concerns that search engines are retaining information on users for too long, European data protection supervisor Peter Hustinx said.
Hustinx, a senior member of the working group, declined to name the companies. But they are believed to include Yahoo, Lycos and Microsoft's Windows Live.com.
The working group will make a general assessment of the state of European citizens' privacy in relation to search engines at its meeting in October or December, he said.
"We will issue a generic paper from which national data protection authorities can address players in their jurisdictions," Hustinx said
Google does present specific problems because so many of its services pose a possible threat to privacy, Hustinx added. He mentioned Google Earth and Gmail, Google's web-based email service. Compiling information about people from the various different web services could compound the threat to privacy, he said.
Google replied to the letter it received from the working group last month, saying it would make user data stored in its server logs anonymous after 18 months.
"The use of the internet the way Google is doing it could introduce tremendous privacy problems. We will study the company's response to our letter very carefully," Hustinx said.
"If the picture they give is not accurate or not justified we might find ourselves on a collision course," he said, but added, "That's not my sense at the moment."
Google also promised to look at shortening the lifespan of the cookies it deposits on computers. The company presently stores cookies, including ones that remember what language a person speaks, for 30 years.
Hustinx is impressed with Google's cooperation so far. "I welcome a big company that is investing in privacy. This isn't just window dressing," he said.
Broadening the EU working group’s examination beyond Google is an obvious next step, according to Danny Sullivan, who writes for searchengineland.com.
He compared the cookie policies of Google, Windows Live and Yahoo and found that Yahoo stores the data for as long as Google while Windows Live holds the information for 14 years.
But Windows Live deposited far more cookies on computers than Google and Yahoo. Using a clean version of Windows Internet Explorer 7, Sullivan set it to reveal all cookies. Windows Live left 14 cookies as soon as he did a search; Yahoo left six, while Google left just two.
"Both Google and Yahoo have 30-year cookies. So where's the letter for Yahoo from the Working Group? And isn't 14 years from Microsoft excessive?" Sullivan wrote.
Yahoo and Microsoft both said they took privacy very seriously.
"Microsoft has a long-term commitment to providing customers with control over the collection, use and disclosure of their personal information.
“While we have not received formal communication from the Article 29 Working Party, we recognise that online search is creating legitimate concerns about privacy and are actively engaged with data protection authorities around the world to ensure that our practices meet the highest standards when it comes to protecting privacy," Microsoft said.
Yahoo said: "Our users' trust is one of Yahoo's most valuable assets. That's why maintaining that trust and protecting our users' privacy is paramount to us. Our data retention practices vary according to the diverse nature of our services," .