A new study has shown how popular dating apps such as Tinder, OK Cupid and Grindr are selling user data to third parties for advertising purposes.

It’s not just dating apps, either. The same study also revealed how period tracking apps are also selling intimate information. The personal data bought by these brokers might reveal date of birth, gender, location, ID numbers stored on phones, behavior, sexual orientation, and religious preference — potentially identifying particular individuals.

The investigation was undertaken by a privacy advocacy group called the Norwegian Consumer Council, and its researchers said they looked at 10 apps in total and the 135 companies to which they were selling user data. They said most of the companies were brokers that few people have heard of, but some of the data buyers were big names such as Facebook Inc., Google LLC and Amazon.com Inc.

The group said this was against the law according to European General Data Protection Regulation. It will be filing a complaint against Grindr and five companies that received personal information from the app. One of those companies was Twitter Inc. and another was AT&T Inc.

Just today, Twitter suspended Grindr from the platform. “We are currently investigating this issue to understand the sufficiency of Grindr’s consent mechanism,” a Twitter spokeswoman said in a statement. AT&T Inc. has yet to respond.

“These practices are out of control and in breach of European data protection legislation,” said Finn Myrstad, director of digital policy at NCC. “The extent of tracking makes it impossible for us to make informed choices about how our personal data is collected, shared and used.”

Following the report, a handful of consumer groups in the U.S. sent letters to American regulators, according to The New York Times, asking them if the new revelations show a breach of federal and state laws.

“This massive commercial surveillance is systematically at odds with our fundamental rights and can be used to discriminate, manipulate and exploit us,” said Myrstad. “The widespread tracking also has the potential to seriously degrade consumer trust in digital services.”

Photo: James/Flickr