1. PARENTAL OR SOCIAL SUPPLY
New Zealand adolescents commonly source their alcohol from their parents (who buy it for and/or give it to them) and friends. Over one-quarter of adolescent drinkers obtain alcohol from an older peer or adult who buys it for them .
Three-quarters of adolescent drinkers aged 16-17 years in New Zealand report consuming alcohol at someone else’s home or in their own home . Almost one-third of 16-17 year olds report consuming alcohol at a pub, hotel, restaurant or café and almost one-quarter at an outdoor public place.
Parental supply of alcohol has been linked to risky drinking among adolescents . Social supply (from peers, siblings and other adults) appears to be more risky than parental supply .
2. OFF-LICENCE AVAILABILITY (DENSITY AND HOURS)
One in every 13 (7.8%) New Zealand adolescent drinkers under the legal purchase age report being able to buy alcohol themselves. Of students who buy their own alcohol, 68.9% report buying it from a bottle store, 14.6% from a supermarket and 16.5% from other places. One-quarter (25.1%) of students who purchase their own alcohol report that they almost never or hardly ever are asked for ID. This prevalence is higher (27.8%) amongst students living in neighbourhoods of high deprivation .
The off-licence environment will be particularly important for adolescent drinking given the consistent evidence showing their price sensitivities in relation to alcohol purchases . An increasing physical availability of alcohol can drive price competition which may lead to adolescents being able to purchase alcohol at lower prices .
High quality research examining the impact of alcohol outlet density in Auckland has shown that the total density of alcohol outlets within a 10km drive was associated with higher typical quantities of alcohol consumed by adolescents . The frequency of drinking occasions was unrelated to alcohol outlet density. The study was not able to examine any differential impact of off-licence, on-licence or club licence density on adolescent drinking.
These New Zealand findings concur with the wealth of international research showing an association between outlet density and increased adolescent drinking [9-16]. In 2016, an Australian study  found that total alcohol outlet density was associated with the prevalence of drinking among adolescents one year later. Elasticity estimates demonstrated that a 10% increase in overall density was associated with a 17% increase in the odds of drinking in the following year.
Research in Australia has also shown that high alcohol outlet densities are associated with higher parental supply of alcohol  and an increased prevalence of minors being able to purchase alcohol .
There are also concerns that exposure to outdoor alcohol advertising associated with alcohol retail outlets may be harmful to adolescents. In the United States, exposure to alcohol advertisements around schools at the age of 11-12 years was found to predict intentions to use alcohol 2 years later .
Most research has focused on the density of off-licences within the neighbourhood, or proximity to off-licences from an adolescent’s residential neighbourhood. Only one study has examined the effects of off-licence outlets in close proximity to schools. This study, conducted in Switzerland, found that the perceived alcohol outlet density surrounding the school (as perceived by the school principal) was associated with increased frequency of drinking and drunkenness by the students .
Compared to studies of adult populations, there are fewer studies examining the impact of off-licence trading hours on adolescent drinking. In Switzerland, one province reduced their off-licence trading hours from 24 hours per day to 7.00am to 9.00pm, and also prohibited the sale of alcohol from petrol stations and video stores. An examination of the effect of the policy change demonstrated that it led to an estimated reduction in the rate of hospitalisation due to intoxication by 35.7% among 10-15 year olds, and a 24.6% reduction in 16-19 year olds .
In a province of Germany, trading hours for off-licences were reduced from 24 hours per day to 5am to 10pm. When compared to the control provinces, the policy resulted in 7% fewer hospitalisations for intoxication among adolescents aged 15-19 years .
New Zealand research has yet to examine the effects of trading hours on those under the minimum legal purchase age. In adults, purchases from off-licences after 10pm were approximately twice as likely to be made by adult heavier drinkers (those drinking larger quantities and/or more frequently) .
In the Youth’12 survey, drinking occasions of New Zealand adolescents commonly occurred with friends (83%), family (53%), and/or with another person (15%) . A higher proportion of students who lived in deprived neighbourhoods (59%) drank with their family when compared to those living in the least deprived neighbourhood (49%). Given that alcohol is most commonly sourced from parents and over one-half of adolescent drinkers consume alcohol with their family, restricted trading hours which reduce adult purchases are likely to play a role in reducing the harm from adolescent drinking. This is supported by Australian research showing that high off-licence availability was associated with increased parental supply of alcohol .
In a multi-country study, adolescent drunkenness has been shown to be significantly associated with high adult alcohol consumption and risky drinking patterns in the adult population . Therefore, policies which impact adult consumption of alcohol are likely to have positive flow-on effects to adolescents.
New Zealand research has demonstrated that the proximity and density of alcohol outlets have disproportionate adverse effects on Māori and Pacific males aged 15–24 years and European females aged 15–24 years . The reasons for these findings warrant further research, but may point to reduced mobility and transportation access in Māori and Pacific populations, resulting in the neighbourhood alcohol environment having stronger effects. It is known that low income groups spend more time in socio-economically disadvantaged neighbourhood when compared to high income groups . This pattern of movement will likely increase exposure to high densities of alcohol outlets present in other disadvantaged communities.
3. ON-LICENCE AVAILABILITY
In New Zealand, almost one-third of 16-17 year olds reported consuming alcohol at a pub, hotel, restaurant or café . In Australia, the density of bars, taverns, restaurants and café’s has been shown to be significantly associated with young adolescent drinking .
Research in the Manukau region has also shown that the density of restaurants and cafés was associated with increased call outs for family violence (which includes child abuse) [32,33]. As noted earlier, many of these incidents are likely to have adolescents and children present.
The strong support for the role of the Social Learning Theory in adolescent behaviour has implications regarding on-premises drinking. This theory suggests that adolescent behaviours are guided by the expectations for the outcomes of those behaviours. Expectations regarding behaviours are acquired through social interactions and role modelling by others . As such, the violence associated with on-premises drinking may play a role in an adolescent’s expectations regarding alcohol-related aggression.
Research examining the impact of outlet density in Manukau has shown on-licence density to be associated with violent offences . Adolescent expectancies regarding alcohol-related aggression may be developed as a result of others’ modelling aggressive behaviour under the influence of alcohol. Unless on-licence violence is curbed, these expectancies among adolescents are likely to influence their own behaviour when they reach the age to purchase alcohol from on-licence premises.
Finally, when the perceptions of Auckland children (aged 9-12 years) were examined in the “Kids in the City” study, aspects of neighbourhoods that children most disliked included drunk people (in the inner-city and low income suburban neighbourhoods) . Noise from drunken parties in some lower-income suburban neighbourhoods also kept children awake at night.