BOSTON (AP) – Violence, sex, and profanity in movies increased significantly between 1992 and 2003, according to a new Harvard study.

Research by the Kids Risk Project at the Harvard School of Public Health found a “ratings creep” for movies, and suggested that the Motion Picture Association of America was relaxing standards in rating films.

The study suggested that films rated PG and PG-13 had become more violent; that there was more sexual content in PG, PG-13, and R films; and more profanity was used in films rated PG-13 and R.

The researchers said the current rating system does not adequately describe the contents of movies.

“Parents and physicians should be aware that movies with the same rating can differ significantly in the amount and types of potentially objectionable content. Age-based ratings alone do not provide good information about the depiction of violence, sex, profanity and other content, and the criteria for rating movies became less stringent over the last decade,” the study found.

“It’s time for a significant research effort to explore the development and creation of a universal media rating system,” Kimberly Thompson, the associate professor who directs the Kids Risk Project, said in a statement.

The study also found more violence in animated G-rated films than in non-animated films with the same rating and emphasized that animation doesn’t guarantee appropriate content.

“Parents must recognize their responsibility in choosing appropriate films with and for their children, and in discussing the messages in films with children to mediate any potential adverse effects and reinforce any potential beneficial effects,” the study said.

The study “gives scientific proof” to parents’ suspicions about the rising amount of sex and violence in movies, said Jim Steyer, founder of Common Sense Media, a San Francisco-based advocacy group that monitors media content for children.

“Parents don’t know what the ratings mean anymore,” he said. “Sometimes you have to spend half your time with your hand over your kid’s eyes.”

Steyer said the current ratings system is flawed because it’s run by an industry board under commercial pressure to pack as much as possible into movies, even if it might be inappropriate for its age rating.

“Why are the foxes guarding the chicken coop? Why is the industry rating itself?” Steyer said. “No one wants to be dictated to about what’s right or wrong, they want to know what’s in it. Right now the system is pretty poor, at best.”

AP-ES-07-14-04 1508EDT