Reviewing several recent surveys of young people, the authors note that underage smokers can acquire cigarettes easily, often from friends and relatives. Most regular smokers aged 12-15 also say they buy cigarettes from shops.
Around 80% of 15 year olds say alcoholic drinks are very or fairly easy to obtain. Friends and relatives are the most common source, but by age 15, a substantial minority say they buy from pubs, off licences or shops, and by the age of 16-17, most drinkers usually buy alcohol themselves.
Around 10-20% of 10-12 year olds, and two thirds of 15 year olds, say they have been offered other drugs (boys slightly more than girls). About a quarter of 15 year olds say cannabis can easily be bought at school, and at least 10% claim to have been offered heroin, cocaine, or crack cocaine.
The authors go on to summarise research findings across the field about the effects of measures to control availability. Increasing the price of tobacco and alcohol is likely to reduce young people's demand for them, say the authors.
Demand for illicit drugs is also price sensitive, but there is little evidence that enforcement measures targeting the drug supply chain have had any effect on street prices, let alone on drug use.
Research has also shown that rigorously enforcing the minimum purchase age can reduce underage sales of tobacco and alcohol. However, state control of commercial markets is clearly only part of the picture, say the authors. Young teenagers, and experimental or occasional smokers and drinkers, are more likely to obtain their supplies from social sources such as friends and relatives.
There is clearly more to learn about the role of social and illicit markets, and the effects of intervening in these markets, on young people's patterns of consumption and their health consequences, they conclude.