Humans have been consuming<unk> since prehistory, although in the 20th century there was a rise in its use for recreational, religious or spiritual, and medicinal purposes.  It is estimated that about four percent of the world's adult population use<unk> annually. The possession, use, or sale of psychoactive<unk> products became illegal in most parts of the world in the early 20th century.  Since then, some countries have intensified the enforcement of<unk> prohibition while others have reduced the priority of enforcement, almost to the point of legalization, as is the case in the Netherlands.
The production of<unk> for drug use remains illegal throughout most of the world through the 1961 Single Convention on Narcotic Drugs, the 1971 Convention on Psychotropic Substances, and the 1988 United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances, while simple possession of small quantities is either legal, or treated as an addiction rather than a criminal offense in a few countries.  The laws in the United States vary from state to state, 13 of them now having decriminalized the possession of small amounts of marijuana for medical use (), although it is still a federal crime.
Cannabis 
Heroin
Benzidine
Phencyclidine
Medical cannabis
Methamphetamine
Nicotine 
Nicotine