This article relies largely or entirely on a single source. (October 2020)
The classical model of drug cutting, according to Preble and Casey (1969), refers to the way that illicit drugs were diluted at each stage of the chain of distribution.
Drug markets have changed considerably since the 1980s; greater competition, and a shift from highly structured (and thus controlled) to greatly fragmented markets, has generated competition among dealers in terms of purity. Many drugs that reach the street are now only cut at the manufacture/producer stage, and this may be more a matter of lacing the drug with another substance designed to appeal to the consumer, as opposed to simple diluents that increase the profit for the seller. The extent of cutting can vary significantly over time but for the last 15 years drugs such as heroin and cocaine have often sat at the 50% purity level. Heroin purity sitting at 50% does not mean 50% cutting agents; other adulterants could include other opiate by-products of making heroin from opium. Coomber (1997d), after having street heroin seizures from the UK re-analysed, reported that nearly 50% of the samples had no cutting agents present at all. This means that 50% of street heroin in the UK in 1995 had worked its way from producer to user without being cut at any stage, although other adulterants may have been present. Other research by Coomber (1997b) outlined how drug dealers have other ways of making profit without having to resort to cutting the drugs they sell.
Cocaine has been cut with various substances ranging from flour and powdered milk to ground drywall and other common, easily obtainable substances.
Most hard drugs are adulterated to some degree. Some street drugs can be as low as 10–15% of the active drug, with the other (85–90%) not necessarily being the cutting agent. In fact a heroin sample of only 20% purity may have no cutting agents in it at all. The other 80% may be impurities produced in the manufacturing process and substances created as by products of this process and/or degradation of the drug if improperly stored.
When choosing a cutting agent, the drug manufacturer or dealer would ideally attempt to find a chemical that is inexpensive, easy to obtain, relatively non-toxic, and mimics the physical attributes of the drug to be adulterated. For example, if a drug is soluble in water, the preferred adulterant would also be water-soluble. Similar melting and boiling points are also important if the drug is to be smoked.
- Vitamin E acetate is used as a cutting agent for THC. Although harmless when used orally, the substance causes vaping-associated pulmonary injury when inhaled.
- The Sun, Lena (6 September 2019). "Contaminant found in marijuana vaping products linked to deadly lung illnesses, tests show". The Washington Post. Retrieved 2019-09-09.
- Coomber, R. (1997a) Vim in the Veins – Fantasy or Fact: The Adulteration of Illicit Drugs, Addiction Research, Vol 5, No. 3. pp. 195-212
- Coomber, R. (1997b) The Adulteration of Drugs: What Dealers Do, What Dealers Think, Addiction Research, Vol 5, No. 4. pp. 297-306
- Coomber, R. (1997c) ‘Adulteration of Drugs: The Discovery of a Myth', Contemporary Drug Problems, Vol 24, No. 2. pp. 239-271
- Coomber, R. (1997d) ‘How Often Does the Adulteration/Dilution of Heroin Actually Occur: An Analysis of 228 ‘Street' Samples Across the UK (1995–1996) and Discussion of Monitoring Policy', International Journal of Drug Policy, 8(4): 178-186
- Preble, E. and Casey, J.J. (1969) `Taking Care of Business – The Heroin User's Life on the Street', in, International Journal of the Addictions, 4, pp. 1-24.