"In the operating guidelines on the early warning system, EMCDDA [European Monitoring Centre on Drugs and Drug Addiction] made it explicit that 'the term ‘new’ did not refer to newly invented, but rather ‘newly misused’' substances as 'most of the drugs in question were first created many years ago.'20 In fact, investigations into the potential use of piperazines as anthelmintic have been reported in scientific literature since the early 1950s.21 Yet they only started to emerge as a health problem in several countries in the decade 2001-2010. Similarly ketamine, which was first developed in the mid-1960s, started to emerge as a health problem in that decade in several countries of East and South-East Asia. Mephedrone was first synthesized in 1929 but was rediscovered only in 2003 and reached the markets towards the end of the decade 2001-2010.22
"NPS also include plant-based substances that have existed for centuries. In the profiles of 'new drugs', EMCDDA lists plant-based substances such as Salvia divinorum and khat. Khat has been known for hundreds of years in the countries around the Horn of Africa and the southern parts of the Arabian peninsula. However, it is considered to be a new substance in a number of European and American countries, as its use was barely known in those regions until one or two decades ago. The same applies to Salvia divinorum, kratom, and various hallucinogenic mushrooms, which are all considered to be NPS.23 Using the definition 'newly misused on the market', the overwhelming number of non-controlled psychoactive substances can be regarded as NPS, as there will always be some countries in which they have not been misused before."
UNODC, World Drug Report 2013 (United Nations publication, Sales No. E.13.XI.6).