Google’s online filing cabinet for medical records opened to the public Monday, giving users instant electronic access to their health histories while reigniting privacy concerns.

Called Google Health, the service lets users link information from a handful of pharmacies and care providers, including Quest Diagnostics labs. Google plans to add more.

Similar offerings include Microsoft Corp.’s HealthVault and Revolution Health, which is backed by AOL co-founder Steve Case.

Google Health differentiates itself from the pack through its user interface and things like the public availability of its application program interface, or API, said Marissa Mayer, the Google executive overseeing the service.

The service, still a non-final “beta” version, does not include ads. But Mayer said Google doesn’t plan to start placing them to support the site. A search box on Google Health pages leads to standard Google search results pages, where there are advertisements.

Besides importing records from providers, users can enhance their password-protected profiles with details such as allergies and medications, they can search for doctors and they can locate Web-based health-related tools.

Mountain View-based Google Inc. views its expansion into health records management as logical because its search engine already processes millions of requests from people trying to find information about injuries, illnesses and recommended treatments.