A recent study revealed that the hottest topics of discussion on the social networking giant MySpace are sex, violence and alcohol use. The fact that about 54 percent of teens talk about those things online presents a potential risk even if it’s just chit chat.

The authors of the study looked at 500 MySpace profiles of people who identified themselves as 18-year-old residing in the United States. Many of them uploaded photos in connection with their discussions about sex or violence. However, although many talk about things like these, in real life many of them do not actually engage in such activities, said Dr. Megan Moreno of the University of Wisconsin School of Medicine and Public Health.

"It's really not that MySpace is bad or good. I think the lesson is that it's a tool, and how you use it determines the kinds of outcome you're going to get," Moreno said.

Nevertheless, talking about sex, violence and alcohol use means that they are thinking about it. Some may just brag about something without actually doing it. But this can still affect the way they will behave in the future, according to Dr. Dimitri Christakis, professor of pediatrics at the University of Washington and director of the Center for Child Health, Behavior and Development at Seattle Children's Hospital.

A teenager who gets a positive feedback after bragging about something that he did not actually do might be encouraged to actually do it, while those who support his actions will also consider doing it.

The authors of the study also identified 190 profiles of 18- to 20-year-olds that contained three or more references to sexual behaviors or alcohol use. Then they made a profile called “Dr. Meg” and from it sent a single e-mail to half of those profiles. The e-mail warned the owners of the profile about the risky information and offered info about clinical resources.

The reaction: 42.1 percent of those who received the e-mail and 9.5 percent of those who did not removed the references or made their profiles private.