Parents and concerned adults have long worried about rap music's effects on children, with its sexual and sometimes violent imagery and lyrics. Now, one study of teen girls has linked large amounts of rap video viewing to risky or violent behavior.

Last year, researchers from Emory University in Atlanta and the University of Alabama at Birmingham reported on a study involving 522 black females enrolled in school health classes or county health clinics in the Birmingham area. The girls, ages 14 to 18, live in nonurban, poorer areas and were or had been sexually active.

At the start of the study, girls who were willing to participate filled out a lengthy survey on musical preferences, parental influence, drug/alcohol use, sexual activity and violent behavior, such as whether they had hit a teacher or been arrested. They filled out a similar survey a year later.

"We wanted to know if there was a correlation or an association between how frequently the behaviors occurred and how much rap music videos they watched," said principal researcher and associate professor Gina Wingood of the Rollins School of Public Health at Emory University.

Researchers didn't track the girls in the 12 months between surveys, nor did they know anything more about the girls than what was reported on the survey.

What they found was that compared to girls who didn't watch rap videos, those who watched 14 hours or more a week were three times more likely to have hit a teacher, 2.5 times more likely to have been arrested, twice as likely to have multiple sexual partners and 1.5 times more likely to have a sexually transmitted disease, use drugs or use alcohol.

So does this mean rap made these girls commit harmful acts?

"It's not rap. It's the amount of exposure," Wingood said. "If a young girl views or is exposed to more than 14 hours of rap music video a week, then there's a much higher probability of her having more health outcomes."

Wingood said the study is being expanded to include a broader range of people.

"Now, we are doing a national study with adolescents throughout the United States, and we're looking at girls, guy, whites, blacks, just everything," she said.

REPORTER: Amber Gray, 13.