(CNN) -- When Vanessa Hudgens' naked photos hit the Internet, the "High School Musical" star quickly apologized. But sending nude or seminude pictures, a phenomenon known as sexting, is a fast-growing trend among teens.

Phillip Alpert is a registered sex offender as a result of sending a nude photograph of his 16-year-old girlfriend.

The National Campaign to Prevent Teen & Unplanned Pregnancy, a private nonprofit group whose mission is to protect children, and CosmoGirl.com, surveyed nearly 1,300 teens about sex and technology. The result: 1 in 5 teens say they've sexted even though the majority know it could be a crime.

Phillip Alpert found out the hard way. He had just turned 18 when he sent a naked photo of his 16-year-old girlfriend, a photo she had taken and sent him, to dozens of her friends and family after an argument. The high school sweethearts had been dating for almost 2½ years. "It was a stupid thing I did because I was upset and tired and it was the middle of the night and I was an immature kid," says Alpert.

Orlando, Florida, police didn't see it that way. Alpert was arrested and charged with sending child pornography, a felony to which he pleaded no contest but was later convicted. He was sentenced to five years probation and required by Florida law to register as a sex offender.

"You will find me on the registered sex offender list next to people who have raped children, molested kids, things like that, because I sent child pornography," says Alpert in disbelief, explaining, "You think child pornography, you think 6-year-old, 3-year-old little kids who can't think for themselves, who are taken advantage of. That really wasn't the case."

Alpert's attorney Larry Walters agrees and he's fighting to get Alpert removed from Florida's sex offender registry. The law lags behind the technology, he says. "Sexting is treated as child pornography in almost every state and it catches teens completely offguard because this is a fairly natural and normal thing for them to do. It is surprising to us as parents, but for teens it's part of their culture."

In many states, like Florida, if a person is convicted of a crime against children, it automatically triggers registration to the sex offender registry. Thirty-eight states include juvenile sex offenders in their sex offender registries. Alaska, Florida and Maine will register juveniles only if they are tried as adults. Indiana registers juveniles age 14 and older. South Dakota registers juveniles age 15 and older. Most states allow public access to sex offender registries via the Internet and anyone with a computer can locate registered sex offenders in their neighborhoods.

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A number of states have elected not to provide Internet access to registries; Florida is not one of them. There is no hiding for Alpert, whose neighbors, he says, all know. "I am a sex offender. If you type my name into the search engine online, you will find me."

As sexting incidents pop up around the country, prosecutors are trying to come to terms with how these cases should be handled. George Skumanick Jr., a district attorney from Wyoming County, Pennsylvania, took a novel approach when 20 students from Tunkhannock High School were caught allegedly sexting.



He gave them a choice: probation and re-education classes or be charged with sexual abuse of a minor. "An adult would go to prison for this," says Skumanick, adding, "If you take the photo, you've committed a crime. If you send the photo, you've committed a different crime, but essentially the same crime."

Critics, however, say child pornography laws on the possession or dissemination of graphic images were never meant to apply to teen sexting and that these teenagers usually have no criminal intent when they send pictures to each other.

amFIX: Should teens be prosecuted for "sexting"?

Fifteen-year-old Marissa Miller of northeastern Pennsylvania was 12 when she and a friend snapped themselves wearing training bras. "I wasn't trying to be sexual," she says, "I was having fun with my friends at a sleepover, taking pictures, dancing to music." The picture recently surfaced on a student's cell phone and Marissa's mom, MaryJo Miller, was contacted by Skumanick. "He told me that he had a full nude photo of my daughter," says MaryJo Miller, who calls the picture innocent.

Rather than force her daughter to take the classes, which would have required she write a report explaining why what she did was wrong, Miller and two other families ­-- with the help of the ACLU -- are suing the district attorney to stop him from filing charges. "We believe she was the victim and that she did nothing wrong," says Miller. "How can I ask her to compromise her values and write this essay, when she didn't do anything?"

Although the district attorney maintains the program is voluntary, the letter he sent to parents notes, "Charges will be filed against those who do not participate." Seventeen of the 20 students caught in the sexting incidents have completed the 14 hours of classes.

Skumanick won't comment on the Miller case, but says, "You can't call committing a crime fun or a prank. If you do that, you can rob a bank because you think it's fun." In the majority of sexting cases, it's usually girls sending pictures to boys, who then send them to their friends. Though teens may think it's funny and a way to flirt or even seek revenge after a breakup, there can be dangerous consequences.

Last year, Jessica Logan, a Cincinnati, Ohio, teen, hanged herself after her nude photo, meant for her boyfriend, was sent to teenagers at several high schools. For months after, her father says, she was the subject of ridicule and taunts. "Everyone knew about that photo," Bert Logan says. "She could not live it down." On July 3, his wife found her. "She had been getting dressed to go out. The curling iron was still warm. It was so unexpected," Logan says. "I heard my wife scream, I ran up to Jessie's room, but it was too late."

No charges had been filed against Jessica's 19-year-old boyfriend, who disseminated the photo, nor had the school taken any action, Logan says. He says he and his wife want to warn parents and students of the dangers of sexting. The Logans are fighting to raise awareness nationally and to advocate for laws that address sexting and cyber-bullying.

As for Alpert, life is not easy as a registered sex offender, a label he will carry until the age of 43. He's been kicked out of college, he cannot travel out of the county without making prior arrangements with his probation officer, he has lost many friends and is having trouble finding a job because of his status as a convicted felon. He says he feels terrible about sending the photo of his ex-girlfriend, especially since they were once so close.

At the same time, Alpert says, "I'm being punished for the rest of my life for something that took two minutes or less to do." Says attorney Walters, "Some judges have the good sense and reasonableness to treat this as a social problem and others are more zealous in their efforts to put everybody away and I think it's time as a society that we step back a little bit and avoid this temptation to lock up our children."

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