The consumption of alcohol, tobacco and marijuana has dropped among Australian teenagers.

New research tracking adolescent health since 1999 shows the number of teenagers who had consumed alcohol fell from 69 per cent to 45 per cent during the period, tobacco use dropped from 45 per cent to 10 per cent, and marijuana use fell from 15 per cent to 4 per cent during the same period.

The study’s authors, from Deakin University and the Murdoch Children’s Research Institute, say the drop could be linked to stricter parental attitudes regarding alcohol, and law reforms reducing the availability of the substances.

The proportion of parents supplying alcohol to their kids dropped from 22 per cent to 12 per cent between 2007 and 2013, while underage purchases of alcohol were found to have fell from 12 per cent to just 1 per cent between 1998 and 2013.

“We can see that parents are taking on the advice from our national health guidelines,” lead researcher Prof John Toumbourou told reporters.

“It shows parents are making radical changes in their attitude to underage drinking and also how they model their own drinking behaviour.”

The study surveyed 41,328 Australian adolescents – with an average age of 13 and a half – between 1999 and 2015.

The researchers say a “normative change” in attitudes towards teen drinking could have been triggered by a 2009 change to Australia’s national health guidelines.

From 1998 to 2007, parental supply of alcohol increased from 15 per cent to 22 per cent, before then dropping to 12 per cent by 2013. 

“In 2009, the national health guidelines were changed to clearly say young people shouldn’t drink until 18,” Dr Toumborou said.

“They were widely promoted from that time onwards.

“By 2011, a number of states had brought in legislation making it illegal for adults to provide alcohol to young people without the parents’ permission. That was a game-changer. Parents realised they needed signed permission if they were going to host a party serving alcohol.”

Australia outperformed Britain and Europe in reducing alcohol use by teenagers over the same period. 

“The United States led this movement, and then Australia has been the next one,” Dr Toumborou said.

“Internationally we probably need to encourage other nations to look at this as an achievable public health target.”

The study is accessible here.