It seems that US college students are still lighting up — but this time it may not be cigarettes they're lighting.
In a new study, researchers from the University of Michigan (U of M) found that daily marijuana use has been steadily increasing in recent years on college campuses, surpassing daily cigarette smoking for the first time last year.
This finding was part of Monitoring the Future, a yearly national survey from U of M's Institute of Social Research. According to the survey, almost 6 percent of college students smoke pot daily — the highest number since 1980 (when data was first available).
Daily use was defined as use on 20 or more occasions in the 30 days prior to the survey.
This increase — up from 3.5 percent in 2007 — reflects a trend of higher marijuana use overall, according to these researchers.
"It's clear that for the past seven or eight years there has been an increase in marijuana use among the nation's college students," said lead study author Lloyd Johnston, PhD, a research professor at U of M, in a press release. "And this largely parallels an increase we have been seeing among high school seniors."
The survey also revealed that monthly pot use among college students rose from 17 percent in 2006 to 21 percent in 2014, while yearly pot use rose from 30 to 34 percent.
According to Dr. Johnston and team, much of this increase may be the result of shifting opinions on marijuana use.
In 2006, 55 percent of high school graduates ages 19 to 22 saw regular marijuana use as unsafe, while only 35 percent saw it that way in 2014.
The science behind just how dangerous marijuana use may or may not be varies.
One study published last month in the journal Psychology of Addictive Behaviors found no negative health outcomes — including asthma, depression or cancer — for adult males who had used marijuana since their teen years.
Other studies, however, have found that heavy pot use can negatively affect cognitive function and increase cancer risk.
According to the National Institute on Drug Abuse, marijuana is addictive and its negative mental and physical health effects may be long-lasting or even permanent.
In spite of this, numerous studies have linked marijuana use to possible health benefits, including use as a treatment for epilepsy, Alzheimer's disease, glaucoma and arthritis.
According to Dr. Johnston and team, the survey — which also covered use of drugs like cocaine, heroin and LSD — revealed some positive news about illegal drug use on college campuses.
"There is some more welcome news for parents as they send their children off to college this fall," Dr. Johnston said. "Perhaps the most important is that five out of every 10 college students have not used any illicit drug in the past year, and more than three quarters have not used any in the prior month."
This study was published Sept. 1 on the University of Michigan's website.
The National Institute on Drug Abuse funded this research. No conflicts of interest were disclosed.