Children's advocates say there are growing signs that more and more children are being sold for sex and that they're are getting younger and younger.

They also say no one's ever tried to count them until now. Criminal Justice Reporter Solana Pyne has an exclusive look at the preliminary results of a new study.

Teen prostitution. The words usually conjure up images of young girls walking the streets. But a new study, the first in the city to extensively interview sexually exploited children, suggests that many of the conventional stereotypes are wrong.

"The most surprising is the amount of boys that are doing this,” says Meredith Dank.

Dank is one of a group of researchers charged with conducting the first ever large-scale count of sexually exploited youth, or child prostitutes, in the city. She's been interviewing teens and children since last August.

“Our goal was 200, and we currently have about 330 interviews, that range from females, males, trans-genders, 18 and under,” says Dank.

That's at least ten times what other studies have done. And two out of every three young people they've talked to have been male or transgender. Part of that may be due to the fact that they're not going into bars or clubs, where many exploited girls end up.

“It might be that the street work that's being done is mainly boys, and transgenders,” says Dank.

Either way, the numbers are far higher than they expected and the researchers say, these children are often victims of terrible violence.

"I've spoken to a number who have been kidnapped, even taken across state lines,” says Dank. “As far as rape goes, a lot of them are held at gunpoint, by a knife in the car, in a hotel."

Dank's research so far confirms that many were abused physically and sexually even before they began selling themselves. Most are poor, black and Hispanic, from the five boroughs. Many of them have drifted through the city foster care system or simply wound up homeless, on the street.

“They feel there is no other choice in life, that they have to do it, whether it's to support a family, support themselves or support others,” says Dank.

Advocates for these children have high hopes for the study.

“It’s going to be the first time that people in New York city have been able to directly talk to young people who've been sexually exploited,” says Mishi Faruqee of the Juvenile Justice Project.

The researchers aim to finish their analysis and issue a report by the end of the year. That's when they will have an estimate for how many sexually exploited youth there are in the city, and statistics about their experiences.

— Solana Pyne