but that is the issue - what is meant by harm? in any discussion about drug use we have to consider the different elements of harm. i.e harm to the individual, harm to society, the cost of treatment, cost of crime, physical harm, emotional harm - the list goes on.
there is a world of difference between experimental, recreational and dependent drug use. obviously the risk of 'harm' (however you define it) increases with regular drug use.
i don't believe that there is any such thing as 'safe' drug use - the stimulant group of drugs puts tremendous pressure on the heart for example. obviously the risks increase with regular use, increased dosage etc. but i don't believe that anyone could say that, for example, cocaine is not harmful. you can reduce the harm associcated with cocaine use - by not using it too often, not drinking alcohol with cocaine etc. but you can't make it NOT harmful. as i have said imn my previous post the effects of any drug will be dependent on a number of elements - how much is taken, how it is taken, what else is being used, frame of mind of the user etc.
and the discussion here is kind of presuming that people will only use one drug at a time. the reality is that most drug users will use more than one drug - cocaine and alcohol, heroin and crack, heroin and alcohol etc.