While cigarette and alcohol use are declining in the wake of public health campaigns, marijuana use among teenagers is on the rise in the US, says a study.
"Our analysis shows that public health campaigns are working -- fewer teens are smoking cigarettes," said Stephanie Lanza, professor of biobehavioral health at Pennsylvania State University.
"However, we were surprised to find the very clear message that kids are choosing marijuana over cigarettes," Lanza said.
The researchers analysed data from a study that surveyed nearly 600,000 students between 1976 and 2013.
Students were asked about their use of three substances -- alcohol, cigarettes and marijuana -- during the 30 days prior to taking the survey.
The results reported in the Journal of Adolescent Health showed a marked decline in cigarette use and an increase in marijuana use.
The researchers found that marijuana usage significantly went up since 2011. The rate of teenage alcohol consumption has decreased since the mid-1970s, the findings showed.
