Facebook’s advertising policies may have privacy policies that allow advertisers to access information such as a person’s age, gender, race, or religion, according to a study published on Thursday.

The study, from the University of Michigan and Princeton University, found that some Facebook ads contain a statement that states “We use data to tailor advertisements based on a person or demographic group, such as age, race or religion.”

The research also found that Facebook’s policies allow people to view a person with a different age or gender than what was originally recorded, or to see a person appear as older or younger than their actual age.

“People who have seen the ads, or have seen ads from advertisers who are interested in a specific demographic, may think they’re seeing the age or race of the person they’re bidding on,” said Elizabeth Larkin, a professor of public policy at the University at Buffalo.

“But Facebook doesn’t know, it doesn’t have a way to tell.”

Larkin said the data that Facebook provides on ads is incomplete and that it is likely that the company is not complying with privacy laws.

“Facebook could be violating federal law or state law by allowing advertising on people’s profiles, and that violates privacy,” she said.

The company’s advertising policy is a key pillar of its business, Larkin said.

“It’s a huge source of revenue, and it has been for years,” she added.

The research was published online in the journal Computers in Human Behavior, and Larkin and her co-authors used data from Facebook ads from 2014 to 2016.

Facebook does not track how often ads appear in its ads.

The researchers used data collected by a company called Advertiser Insights that monitors more than 200,000 ads for keywords and the age and gender of the audience the ads are being placed on.

Advertiser’s Insights said it does not use any identifying information to track consumers, and did not respond to requests for comment.

Facebook has not released a statement on the findings.

The social network has been criticized by privacy advocates and others for its practices on data collection.

Facebook’s CEO, Mark Zuckerberg, has argued that its data collection practices are legal and ethical.