It's difficult to track when the pageants began and who initially set them up. A keyword search of #beautycontest turned up 8,757 posts, while #rateme had 27,593 photo posts. Experts say those two terms represent only a fraction of the activity. Contests are also appearing on other social media sites, including Tumblr and Snapchat — mobile apps that have grown in popularity among youth.
Facebook, which bought Instagram last year, declined to comment. The company has a policy of not allowing anyone under the age of 13 to create an account or share photos on Instagram. But Facebook has been criticized for allowing pre-teens to get around the rule — two years ago, Consumer Reports estimated their presence on Facebook was 7.5 million. (Washington Post Co. Chairman Donald Graham sits on Facebook's board of directors.)
Although users can keep their Instagram accounts private or use pseudonyms, they can expose themselves to the public once they share their photos with others.
The girls in the beauty contests often did not take care to keep their identities and locations private. Some dressed in shirts embroidered with their schools' names, others provided a link to their Twitter, Facebook or Tumblr accounts containing information about who they are and where they live.
In December, federal officials strengthened privacy rules for children. But analysts say regulators are not keeping abreast of new technological trends that present fresh questions about the safety of children on the Internet.
Instagram, which was acquired by Facebook last year for $1 billion, at first was seen as an easy way for amateur photographers to turn smartphone pictures into a kind of art. But as mobile gadgets have exploded in popularity among pre-teens and teens, youth have used it as their own social network, child online privacy and safety advocates say.
"It's so easy and fun to use, and kids are able to post all the time because they are carrying a smartphone in their pockets all day," said Stephen Balkam, president of the Family Online Safety Institute. A recent report by the Pew Research Center's Internet and American Life Project found four out of 10 teens own smartphones and girls tend to be more active users of the Internet through mobile devices than boys.