In the Journal’s testing, Instant Heart Rate: HR Monitor, the most popular heart-rate app on Apple’s iOS, made by California-based Azumio Inc., sent a user’s heart rate to Facebook immediately after it was recorded.

Flo Health Inc.’s Flo Period & Ovulation Tracker, which claims 25 million active users, told Facebook when a user was having her period or informed the app of an intention to get pregnant, the tests showed.

Real-estate app Realtor.com, owned by Move Inc., a subsidiary of Wall Street Journal parent News Corp , sent the social network the location and price of listings that a user viewed, noting which ones were marked as favorites, the tests showed.

Source: You Give Apps Sensitive Personal Information. Then They Tell Facebook. – WSJ

Thus, apparently deleting the Facebook app from your device to avoid Facebook spying is insufficient as Facebook has been receiving personal data collected by other applications. These actions may violate EU law.

Due to repeated privacy invasions by Facebook, going on for years, it will be necessary for Facebook to be heavily regulated.