TEENAGERS who drink even small amounts of alcohol have a significantly higher risk of developing alcohol abuse or risky sexual behaviour as a young adult, research has found.
The study casts doubt on national guidelines that suggest there is a "low risk" level of drinking for under-18s.
It provides evidence for a move away from the "harm minimisation" approach to teen drinking and could even fuel a campaign to raise the legal drinking age, experts say.
The team at the Murdoch Children's Research Institute in Melbourne say their study, which tracked 1520 young people's drinking habits over more than 10 years from the mid-teens, shows no "safe" or "sensible" level of drinking for adolescents.
Official guidelines from the National Health and Medical Research Council define a "low risk" level of drinking for adults as fewer than three standard drinks a day.
The researchers found that even at this level, teenagers increased their chances of alcohol abuse, social or legal problems, or alcohol-related high-risk sexual behaviours 10 years later.
"The issue of when teens start drinking is very important," said the lead researcher, Elya Moore, an epidemiologist. "Those who abstained from any alcohol in adolescence experienced fewer [bad] alcohol-related outcomes than those who drank at the 'recommended' level.
"We found no evidence of a level that may have been safe. I think that's the most remarkable finding."
The study was published last week in the Australian and New Zealand Journal of Public Health. It found that by young adulthood, 27 per cent of men and 13 per cent of women met at least one of the criteria for alcohol abuse and risky sexual behaviour connected with alcohol use.
The research showed a clear linear trend - the more boys drank in their teen years, the more likely they were to develop alcohol-related problems as young adults.
For girls the trend was less clear. Dr Moore said this could have been a failure of the research method, rather than evidence that girls were more able than boys to drink at safe levels without long-term effects.
Australia's official guidelines, announced in February, say the safest option is to drink no alcohol below the age of 18.
For people aged 15 to 17 they say "the safest option is to delay … drinking for as long as possible", and "if drinking does occur it should be at a low-risk level and in a safe environment".
But the study found that the chance of developing alcohol-related disorders among the "low risk" drinkers was closer to that of "risky" drinkers than to that of non-drinkers.
George Patton, director of adolescent health research at the Royal Children's Hospital Melbourne said he was surprised by the results. He had expected that those with no evidence of excessive drinking as teens would "do well as adults".
"But we found, particularly for males, that those who start drinking early had very high rates of alcohol abuse and dependence, even if they had started [by] drinking sensibly," he said.
He said the study was limited because it could not eliminate other factors such as personality and social background. But it would add to the debate about teen drinking policies.
The chairman of the Alcohol Education and Rehabilitation Foundation, Scott Wilson, said the study suggested that alcohol guidelines should be made clearer - "zero alcohol, full stop" for under-18s.
"The attitude has to change where we think it's not such a big deal for a couple of young boys to have a six-pack of beer," he said.
"You see that attitude when you go to a footy club, say after a [junior league] final when the Coke is quickly replaced by beers. It's that acceptance that has to be changed."