KNOXVILLE (WVLT) – Do you know what is on your child’s cellular phone?

According to Knoxville police, naked pictures and sexual messages are becoming more and more common in the inboxes of area teenagers. Their numbers are backed up by national statistics showing your child may know someone who has sent them something sexual in nature.

The practice has become known as “sexting,” while others refer to it simply as “text sex.”

A recent survey by the National Campaign to Prevent Teen and Unplanned Pregnancy indicates one out of five teenagers have sent nude or semi-naked pictures of themselves or someone they know using their cell phone. About 40 percent admitted they had sent text messages that were sexual in nature.

The numbers correspond with the increase in teens who are using cell phones to stay in contact with their friends and family.

"I have to have my phone,” said Maleah Wolfenbarger, 17 a junior at Central High School. "I text my girlfriends daily."

She told Volunteer TV News that she isn’t surprised at the results of the recent survey. In fact she has seen first hand that there are other teens out there sending text messages that are more than casuals.

"I can name 10 people off the top of my head that do it," she said. “Just nude pictures of everything."

Many teens apparently don't blush about baring it all when it comes to "sexting."

“Guys just ask for it,” she said, “So girls send them, and the guys will send them back."

“Sexting” has become widespread, with Knoxville Police now handling as many as two cases a week.

"As more and more have phones, it becomes a bigger and bigger problem," said Lt. Warren Hamlin from the Knoxville Police Department. "I think kids don't understand what they're doing."

According to the district attorneys office, what many teens now see as harmless flirting, can be seen in the eyes of the law as a crime.

"It's definitely a violation of the law,” said John Gill, from the Knox County District Attorney Generals Office, “it is a felony."

“Sexting” specifically violates the laws concerning manufacturing and distributing pornography. When it comes to enforcing the law, Gill says it depends on content and context.

“The message, the poses, the attitude and even the expression in the picture,” he said, reminding that the law applies even if the teen takes pictures of themselves.

It's also more than just still images. Students admit that they know of some teens who now use cell phones to make videos. Those videos can end up online for anyone to see.

“Once a picture gets on the internet, there is no getting it back,” said Lt. Hamlin.

With 40 percent of teens admitting to sending sexually related messages, that means a flood of explicit material that could be hitting the Internet.

"It's very bothersome," said David Alt, a Knoxville parent. “You've got to trust your kids too, but I'll have a policy where I'll have to monitor pictures and things like that, because that the biggest concern I have."

Wolfenbarger said she thinks the actions of some of her peers are sending the wrong messages about teens.

“It’s just bad for everyone," she said.

Knox County schools are currently on spring break and schools were not available to talk to Volunteer TV News.

The school cell phone policy states phones must be off and in backpack during the school day.

According to John Gill, the district attorney’s office has yet to prosecute any teens for “sexting.” If they did, the cases would all go through the juvenile court system.