The Lancet 24 March 2007
According to research released in the Lancet 24 March 2007, both alcohol and smoking are more dangerous than many illicit drugs including marijuana and poppers. Alcohol and tobacco were in the top 10 while marijuana was 11th and poppers were 19th out of 20.
The researchers were from two different groups and considered experts in their fields. These included law enforcement, chemists, pharmacologists and addiction specialists in the Royal Society of Psychiatrists.
In the UK a system that has evolved over nearly a century regulates illicit drugs according to a classification system that aims to relate to the actual harms and risks of each drug that's been used by a small group of experts, and which has been described as a "rational scale for assessing the harm of drugs of misuse".