Facebook needs to be doing more to help protect minors using its service, according to a letter sent to the company’s top executive by Consumers Union. Consumers Union is the publisher of this blog.

The letter is based on a just-released annual survey by Consumer Reports on the State of the Net. Projections from the survey show that 20 million minors actively used Facebook this past year. Of those, as many as 7.5 million were estimated to be younger than 13, and around 5 million are estimated to be 10 years old and under. Facebook’s policies technically limit membership to individuals 13 and above.

Consumers Union letter to Facebook CEO Mark Zuckerberg pointed out that minors are likely sharing increasing amounts of personal information on Facebook without understanding how that information is used or who it is shared with. Teens may, for example, post photographs depicting underage drinking or illegal drug use or reveal their geolocation information by accessing Facebook through their smartphones.

“Such behavior does not necessarily indicate, as some have suggested, that young people do not care about privacy,” CU Regulatory Counsel Ioana Rusu wrote. “It might demonstrate that minors’ expectations vis-à-vis the way their data is used and shared on Facebook does not coincide with reality.”

To help with the problem, the letter suggested Facebook strengthen its efforts to identify and terminate the accounts of users under 13 years of age, and also put in place better age verification techniques for users signing up for new accounts. In addition, for Facebook users under the age of 18, default privacy settings should be set at the “friends only” privacy setting for all categories of information.

The letter also has several other suggestions for the social media giant to better protect minors. Click here to read the full letter.

As the letter points out, another recent survey by Consumer Reports shows that 73% of Americans support heightened protections for minors’ data online. We agree with that overwhelming majority.