A study has found there is a low level of perceived risk by the group regarding occasional and regular cannabis use.

Almost one in five of all those surveyed supported the legalisation of cannabis — although three quarters said they were not given enough information about the drug.

A survey of more than 500 secondary school students aged 15 to 18 in Cork City and suburbs found that 39% had used cannabis at some stage in their lives.

The study found “cannabis use is very widespread among teenagers in Cork”, adding: “There are relatively low levels of perceived risk of mental and physical health problems with use of the drug.”

This compares to a lifetime prevalence of 33% among those aged 15 to 34 in Ireland, incorporating a significantly older age group.

“This is of concern in school-going teenagers as the lifetime prevalence of cannabis use may continue to increase with higher levels of education in Ireland,” the study said.

“It is likely that some non-users in this study will go on to use cannabis in later years.”

The research was carried out in nine public and private schools — four girls’ schools, four boys’ schools, and one mixed school — among students in fourth, fifth, and sixth year.

It was conducted by Peter Barrett and Colin Bradley, attached to the School of Medicine at University College Cork, and published in the Irish Journal of Medical Science.

Just over half of the 507 students who took part in the study were male and the mean age was 16.7.

More than eight out of 10 said they personally knew someone who had used cannabis and almost four out of 10 (199 students) reported using it themselves at some stage.

A third of these 199 students (66) said they had used the drug more than 10 times.

Of this group, the majority (41) believed recreational use of cannabis should be permitted.

This compared to one in five of those who had used the drug just once. The figure for all students surveyed was slightly less, at 18%.

“Males were significantly more likely to support legalisation and believe that cannabis is a safe substance, compared with females,” the study said.

It said few teenagers perceived a “great risk” of mental health problems or physical health problems as a result of occasional cannabis use — and thought there were relatively low levels of risk from regular use.

The study said that 30% of students reported that they intended to use cannabis in the future, while a further 18% were uncertain about it.