Sending sexually explicit photos or videos via kids' cell phones isn't as widespread as earlier believed, researchers say.

Still, minors who do it can get into legal trouble -- the sexting may be considered child pornography, even if sent from a girl to her boyfriend or vice versa.

"Child pornography is by definition a sexual picture of a minor," said Kimberly J. Mitchell, a psychologist at the University of New Hampshire and co-author of two new reports published in the journal Pediatrics.

In 2008, researchers say, police handled 3,500 cases of sexting by minors in the U.S. Most often, the images were sent to other minors, but in one-third of the cases adults received images. Arrests resulted in 40 percent of cases. According to a study at the time, about 20 percent of teens said they had sent or posted nude or semi-nude images of themselves.

Although sexting has become something of a hot topic in the media lately, just 2.5 percent of teens said they appeared in sexually explicit images and 7 percent said they'd received such images. These findings were based on national phone interviews with 1,500 youth between the ages of 10 and 17 in 2010.

"With any sort of new technology that kids become involved in there is a tendency to become easily alarmed," Mitchell said. "What we are instead seeing is that sexting may just make some forms of sexual behavior more visible to adults."

Still, others wonder if the teens in the study were being entirely truthful.

"It's nothing to panic about, but it's something to address," said Bill Albert, spokesperson for the National Campaign to Prevent Teen and Unplanned Pregnancy. "It's a good opportunity to sit down with your kid and talk about it."