Substances chosen for study and comparison
| Substance | Class in Misuse of Drugs Act at time of data collection |
| Alcohol | Not controlled if over 18 years |
| Amphetamines | B |
| Barbiturates | B |
| Benzodiazepine | C |
| Buprenorphine/Temgesic | C |
| Cannabis | B |
| Cocaine | A |
| Crack cocaine | A |
| Crystal meth | A |
| Dihydrocodeine/codeine/Tramadol | Not controlled |
| Ecstacy/MDTA | A |
| Heroin | A |
| Ketamine | C |
| LSD | A |
| Magic mushrooms | A |
| Methadone | A |
| Nicotine/tobacco | Not controlled if over 18 years |
| Methylphenidate/Ritalin | B |
| Inhaled solvents | Not controlled |