Although adults use these apps both for casual hookups and for scouting out more long-term relationships, they're risky for teens.
For starters, although many of the apps aren't intended for them, it's easy for savvy teens to get around registration-related age restrictions. Location-sharing increases the potential for a real-life meeting; less dangerous but still troubling is the heavy emphasis on looks as a basis for judgment.
It's possible that teens are only testing boundaries with these apps.
Many are eager to be on the same wavelength as their 20-something counterparts, and the prospect of meeting someone outside their social circle is exciting.
And with so much of their social life happening online, teens feel comfortable using apps to meet people.