Over the past few years, the drug scene has witnessed conformational changes, especially due to the emergence of a myriad of novel psychoactive substances (NPS), which are either newly formulated drugs, or existing substances, including medications, which are now being used in new ways. During the later parts of 2015, large amounts of 700 NPS had been reported in many countries all over the world. Nevertheless, more recent data prove that synthetic cannabinoids, synthetic cathinones and psychedelics/phenethylamines represent a great percentage of today's NPS. TOR network and a few other darknets have markedly contributed to the popularization of NPS. However, due to the fact that most NPS are not illegal under many jurisdictions, they are now also sold on some websites on the surface web.

Since the beginning of 2008, the number of NPS reported by the United Nations Office on Drugs and Crime has skyrocketed by more than 800% to 541, far exceeding 244, which is the number of drugs banned under global conventions. As they are often marketed as "research drugs" or "legal highs", NPS are formulated specifically to exploit outdated international legislations.

Even though a group of countries, including USA, have imposed a ban on whole ranges of chemical substances that resemble illegal drugs, many nations have not. The EU particularly, with its enormous open borders along with its disparate drug legislations, represent great opportunities for smuggling contraband. According to Soren Pedersen, the Europol's spokesman "As soon as a substance becomes illegal in Germany, they can just divert it to Denmark, Sweden or Austria.”.

By far, China is the origin of most NPS. The Australian Crime Commission stated that China is the primary source of most newly formulated NPS, especially those resembling amphetamine, which crossed the Australian border between 2013 and 2014.

Types of NPS Available for Sale on The Dark Web and Surface Web:

The following table represents the groups of NPS available for sale mainly on dark web marketplaces, including AlphaBay, Valhalla and Dream Market. There are also a number of websites that sell NPS on the surface web, given the fact that they are not illegal substances under many jurisdictions including Dutch Headshop, Online Smartshop and others.

Synthetic Cannabinoids:

Synthetic cannabinoids have effects that are similar to those of cannabis, yet without imposing a threat on the user of possible legal prosecution. No one can argue the fact that synthetic cannabinoids are the most popular class of NPS. Synthetic cannabinoids were initially developed and experimented upon for their analgesic features and to study the brain's neuronal receptors. Synthetic cannabinoids produce the same effects of cannabis as they activate the CB1 receptors.

Aminoindanes:

Aminoindanes (AIs) affect the uptake and release of serotonin, a chemical neurotransmitter in the brain that controls mood, which is why they are used as psychoactive drugs. 2-AI is the prototype of this class of NPS and represents an analogue of amphetamine. Other members of this NPS class include 5,6-methylenedioxy-2-aminoindane (MDAI), N-ethyl-5-trifluoromethyl-2- aminoindane and 5-iodo-2-aminoindane. On the street, AIs are known as "pink champagnes" and "MDAI-gold".

Phencyclidine-type substances:

Due to the structural resemblance between phencyclidine (PCP) and ketamine, they are both classified as arylcycloalkylamines and they are also often referred to as "PCP-type substances". Ketamine and PCP are medically used in anesthesia. Ketamine usage as an NPS was first reported in the 1990s. On the street, it was referred to as Kit Kat, K, Cat-Valium and Vitamin K. Ketamine is sold in liquid, capsules and powder forms and it is usually injected or inhaled.

Newer forms of PCP-type NPSs include 3-MeO-PCE and 4-MeO-PCP and are often present in the form of powder.

Phenethylamines:

This a diverse category of drugs that include amphetamine, metamphetamine and 3,4-methylenedioxymethamphetamine (MDMA), in addition to ring substituted derivatives including "2C series", "D series", para-methoxy-n-methyl-amphetamine and benzodifurans (Bromo Dragonfly). Street names of this class of NPS include Europa, RDJ, methyl-MA and 4-FMP. They are available in the forms of powder, pills and liquid. They are mostly taken orally.

NPS of Plant Origin:

The following represents the most popular NPS of plant origin that can be bought mainly from the dark web: