Police fear the approaching secondary school ball season could see a repeat of the major disorder and drunkeness seen last year.
In a rare joint statement, police and health officials have urged parents and party organisers to ensure events do not get out of hand.
Police say out-of-control parties have become much more common since the earthquakes.
"Up to 2010 most after-parties were held in central city premises and alcohol consumption was relatively limited and not available to minors on the premises. Now we are dealing with young people drinking considerable quantities of alcohol, at remote, isolated rural locations, with high levels of intoxication."
Last year's ball season saw police called to a number of privately-organised parties which spiralled out of control.
Canterbury Police's alcohol harm reduction manager Senior Sergeant Gordon Spite have asked those organising privately-run parties to notify police so they could be monitored by patrols.
Spite said police were already aware of a number of parties planned for the coming weeks that were "potentially of concern".
"We had major issues with disorder and intoxication at several events last year, particularly some that were held on temporary premises in rural locations. At some parties we were dealing with huge numbers of drunk young party-goers.
"Our concern is that these young people are putting themselves and others at extreme risk in terms of personal safety, drink-driving and road safety," Senior Sergeant Spite says.
Spite said that under new legislation underagers had to have express consent from a parent to be given alcohol.
"That consent has to amount to more than an underage person turning up to a party with a note purporting to be from a parent. Party organisers are required to know that consent has been given."
Spite said the problem was not only with after-ball parties.
"We recently attended an 18th birthday party held at unlicensed commercial premises where assaults had occurred and none of the largely intoxicated organisers could tell us who was in charge.
"In these situations young people are vulnerable to becoming both offenders and victims of crime. The potential for tragedy to occur is extremely high."
Canterbury Medical Officer of Health Dr Alistair Humphrey said such parties often encouraged binge drinking with "far too many underage drinkers" ending up in the emergency department.
"In fact, there are increasing numbers of 14 to 17-year olds presenting to ED with alcohol-related injuries and alcohol poisoning every year and these events contribute to that harm."
Dr Humphrey said research showed the earlier people start drinking, the heavier they drank and the more harm they, and others, suffered.
"As parents, we do not want the legacy of poor supervision being sexual assaults of our daughters, or our sons being assaulted or arrested. Teenagers can have a good time, just like adults, without excessive alcohol," he said.
Humphrey said there was also good evidence that brain development in young people was affected "even by moderate amounts of alcohol".
Both Spite and Humphrey warned parents to be actively aware of the functions their children were attending.
- The Press
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