The study is based on the harm a drug causes to society as well as each drugs individual danagers.

So basically the way they have listed it something low in the list may be more harmful to an individual than something higher up but because its not used as much the overal impact on society is less.

This is actually a pretty good result for Cannabis as its the most widely used "ilegal" drug in the UK but still comes in at 11th. It's the fact both alcohol and tobbacco come in above it that just shows how crazy it is that they are legal but Cannabis is not.

Of course as per normal with this type of study the UK government have quickly come out and said they have no intention of making any changes based on this.