The level of gun violence in PG-13 films in 2012 exceeded that of R-rated releases in the same year, according to a report out this week.

Research by US and Dutch university teams published in the December issue of US journal Pediatrics revealed that gun violence – defined as discharging a gun and hitting a living target – has more than tripled since 1985 in films deemed appropriate for viewers aged 13 and above.

Researchers analysed the number of violent sequences – not exclusively involving guns – in 945 films culled from the top 30 films of each year from 1950 to 2012. Incidents involving rocket-propelled grenades and similar weaponry and hunting scenes were discounted.

On average gun violence appeared in the top 30 PG-13 films of 2012 in approximately three five-minutes sequences per hour, compared to 2.15 five-minute segments for R-rated releases.

The report’s authors said that while gun violence has been on the rise in all films and has more than doubled since 1950, the most marked increase has been in PG-13 material since the ratings category was introduced in 1985.

The report noted that since 2009 gun violence in PG-13 releases has occurred on a par with or more frequently than in R-rated releases.

PG-13 titles that came under scrutiny include The Dark Knight, Terminator Salvation, Transformers: Dark Of The Moon, Captain America: The First Avenger, The Amazing Spiderman and Taken 2.

“We do not draw a direct causal link to the recent rise in school and other public shootings but the rise in gun violence in films certainly coincides with those events,” said co-author Daniel Romer, director of the Adolescent Communication Institute at the Annenberg Public Policy Center at the University Of Pennsylvania.