Young people begin experimenting with smoking and drinking at the age of 13, and drugs come a year later, according to a Church of Scotland survey of more than 2,500 pupils in 57 secondaries. Alcohol and cigarettes remain the number one social and health enemy.
The Church's controversial report into the decriminalisation of some illicit drugs, challenged furiously last week by leading politicians and police officers, will be presented to the General Assembly in May. A study group, under the board of social responsibility, backs a softer line on cannabis without supporting legalisation.
As part of a two-year investigation, the group carried out a survey of 13 to 17-year-olds across Scotland. The findings show that 95 per cent had taken a drink, 64 per cent had smoked and 50 per cent had tried drugs. But only 75 per cent continue to drink, 28 per cent continue to smoke and 23 per cent admit to using drugs. More girls smoked than boys, 32 per cent against 24 per cent.
The danger age for drinking and smoking is 13, although many children begin experimenting a year earlier or a year later. More than a quarter of teenagers try alcohol as 13-year-olds.
Experimenting with drugs usually begins at 14 or 15, but children subsequently tend to avoid them. Although 42 per cent of those surveyed had used cannabis, only half continued. Fewer than half who had tried other drugs continued.
The study stresses that cannabis is only the third most common substance abused after alcohol and tobacco and warns that the Church is sometimes seen as "having a hypocritical attitude in accepting alcohol and tobacco but denying access to other drugs which may be less harmful".
A more enlightened attitude to cannabis may help the Church's standing among the "marginalised of society", the report continues. "The gateway theory that says drug users move from less to more harmful drugs as a matter of course is not proven. There is no evidence that one leads inevitably to another. The fact that all drugs are available from the same source is more likely to be a reason for their connection."
The group calls for a Royal Commission on cannabis and stops short of backing a change in the law. But Tony Blair, launching Labour's anti-drugs campaign last week at Dyce Academy, Aberdeen, criticised the Church's conclusions and supported the city's interdepartmental approach to combating the spread of drugs.
Mr Blair said: "If we had said 10 or 15 years ago that children in 1997 would be able to buy drugs in their schools as a matter of course, we would have been dismissed as alarmist. Yet for many schools, that is the grim reality. It is one we cannot be prepared to tolerate."