(CNN) In 2016, 41% of top-grossing US movies showed people using tobacco, according to a recent report from the US Centers for Disease Control and Prevention , a decrease from the year before. However, there was an 80% increase in incidents of tobacco use in those movies from 2015 to 2016.

The numbers are prompting concern from public health researchers and advocates over the effects these scenes have on young people's behavior.

"We've known for a while that the more you see smoking on screen, the more likely you are to see youth smoking cigarettes in real life," said Michael Tynan, lead author of the report and a public health analyst at the CDC's Office on Smoking and Health. "There's a causal relationship between the two."

The data from the new report were taken from Thumbs Up! Thumbs Down! , a project of the nonprofit Breathe California of Sacramento-Emigrant Trails . Since 1991, the organization has collected data on tobacco use by counting the number of times a tobacco product is used or implied to be used in a movie scene.

The new report crunched the numbers from 2010 to 2016. The use of cigarettes, cigars, pipes, hookahs, smokeless tobacco and e-cigarettes was recorded in each of the top 10 highest-grossing movies at the US box office for each week of each year.

There was a steady decline in the amount of tobacco use shown in movies from 2005 to 2010. But in the next six years, the incidence fluctuated. It reached a peak in 2016, with 3,145 tobacco incidents in 143 movies.

Of 2016's youth-rated movies -- including G, PG and PG-13 ratings -- 26% featured tobacco incidents. Sixty-seven percent of R-rated movies in 2016 had tobacco incidents. Compared with 2010, the percentage of movies depicting the use of tobacco decreased slightly; the 2010 rates were 31% for youth-rated movies and 71% for R-rated.

Tobacco use was featured in 41% of the surveyed movies in 2016, down from 50% in 2015.

However, the number of tobacco incidents within movies actually increased by 72% from 2010 to 2016. And from 2015 to 2016, there was an 80% increase, from 1,743 incidents to 3,145.

"To me, this shows that the studios are capable of reducing the amount of smoking in films," said Stanton Glantz , one of the study authors and a tobacco control professor at the University of California, San Francisco. "They went whole years without showing smoking in youth-rated movies, but they've stopped doing it.

"It was like they were getting the arsenic out of the popcorn," he joked, "but they didn't finish the job."

Tynan, Glantz and their colleagues noted limitations of the report: First, many movies were left out out of the analysis, though they noted that movies ranked in the top 10 usually account for 96% of all ticket sales.

Dan Romer , director of the Adolescent Communication Institute at the University of Pennsylvania, identified another limitation as those was watching the movie were unknown: Audiences could be filled with adults rather than youth.

"I don't want to downplay what they're saying. I think it's important to point out there's still a lot of smoking in movies," said Romer, who was not involved in the research. "But it's hard to know from their study if it's the kind of movies that have a high viewership in adolescents."

Also not accounted for were the numerous TV shows and made for TV movies that could also expose youths to tobacco and smoking.

Suggestions for improvement

The U.S. surgeon general released a report in 2012 directly illustrating a causal relationship between watching smoking in movies and youth starting to smoke.

In response to this, Glantz suggested measures that could be taken by the movie industry to better regulate tobacco depictions.

First, the Motion Picture Association of America , which assigns movie ratings, could give an R rating to any movie with smoking or tobacco use.

"The MPAA needs to modernize the rating system to reflect the conclusive science that putting smoking on a screen increases the chances of youth smoking and then dying prematurely as a result," he said.

Other recommendations include requiring film studios to certify that no payments have been received for using tobacco in movies. He also suggested that state and local governments could decline to give subsidies to films that portray tobacco.

The Motion Picture Association of America, the trade association representing six of the major Hollywood film studios, declined to comment on the new study.

'This person is a risk-taker'

Romer, who conducted a separate study that analyzed the incidence of tobacco use in movies from 1950 to 2006, found a decline over the time period he studied. He believes that this trend paralleled tobacco usage in everyday life through the years.

"The amount of smoking seen in the movies was remarkably consistent with the overall prevalence rates of smoking in the country," he said. "Nowadays, there aren't as many people smoking anymore, so there's also less of that in the movies."

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What is it about smoking in the movies that makes children want to try it? Romer believes it's the "edgy" nature of movie characters.

"Hollywood now uses smoking as a cue to say that this person is a risk-taker and kind of an edgy character," he said. "Not very normative and sort of on the fringe today. And so an adolescent that finds that appealing might say, 'I want to be like that person. I'm going to smoke.' "

Craig Detweiler , a film historian and communication professor at Pepperdine University, said the "coolness" factor is hard for filmmakers to give up.

"There's so many iconic images of cool associated with smoking that it's a hard habit for actors and filmmakers to break," he said. "The tension arises because filmmakers are often going for a particular look or feel. Smoke is very photogenic, and actors are always looking for something to do with their hands, a bit of business."

He added, "I think the challenge is for studio and filmmakers to put ethics ahead of aesthetics."