Home > Forensic Science Laboratory analyses street-level heroin and cocaine.

Connolly, Johnny (2014) Forensic Science Laboratory analyses street-level heroin and cocaine. Drugnet Ireland, Issue 50, Summer 2014, pp. 22-23.

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An analysis of heroin and cocaine seizures submitted to the Forensic Science Laboratory (FSL) between April 2010 and March 2012 sought to assess the current status of these particular drug markets, ‘in order to track changes in the markets, and for comparison to reported European data’.1 The study also sought to establish whether purity plays a role in the pricing of street drugs. This is particularly important in the Irish context as, under the terms of Section 15a of the Criminal Justice Act 1999 (as amended), a mandatory minimum sentence of 10 years applies where a person is convicted of possession of drugs with a market value of €13,000 or more. For the purposes of this legislation, the market value is interpreted as the maximum value a drug could realistically be expected to obtain at street level when purchased by an end user. 

Street-level purity data give an indication of the purity of the substance reaching the end user. Unlike markets for legitimate goods, in the illicit drug trade the quality of the commodity is not regulated or guaranteed and therefore is something than can only be assessed by the user after consumption. As a consequence, just like restaurant meals or used cars, illicit drugs are referred to as ‘experience goods’, as their quality is only fully knowable after use.2 A further complicating factor is that adulterants are added to drugs not only to bulk them up for sale but also to enhance or mimic the effects of the drug for the user. So, for example, where a user might believe the drugs s/he consumes are of a good quality, this does not necessarily mean that they are of a higher purity.3   

In the FSL study, quantitative analysis to determine drug purity was carried out on randomly selected street-level seizures on a monthly basis during the two-year period of the study. Data were also collected on the type and frequency of adulterants detected in the seizures. Price information for a subset of the cases quantified and also for a number of cases not quantified was obtained from An Garda Síochána. 

Findings in relation to heroin seizures

Analysis conducted by the FSL as part of a National Advisory Committee on Drugs and Alcohol/Health Research Board (NACDA/HRB) study of illicit drug markets in Ireland found an average heroin purity of 45% in a sample of 131 heroin seizures from four distinct markets in 2008/2009.4 In the current study, in a sample of 239 diamorphine (heroin) cases the mean purity was 47% for 2010, 30% for 2011 and 24% for the first three months of 2012. The study reveals ‘a general decline of diamorphine purity over the time period, with the 2012 average being nearly half the average purity obtained for 2010’ (p.2). 

Of the 239 heroin samples analysed, 81% contained adulterants/dilutants. The frequency of detected adulterants increased from 67% of cases in 2010 to 100% in 2012. This may help explain the drop in purity during the same period as it was also found that ‘the mean purity of heroin samples with no detected adulterants was 58%, whereas the mean purity…containing adulterants was 31%’ (p.2). The main adulterants found were caffeine and paracetamol, usually together. 

Coomber (2006), in a discussion of drug adulteration, points out that one of the reasons caffeine is commonly found with heroin is that, when heroin is smoked or ‘chased’, caffeine has been shown ‘to enable a higher amount of the heroin (around 76%) to be recovered (i.e. the amount of heroin left available in the ‘smoke’ which is inhaled), after volatization (the heating, melting and then vaporization of the drug for inhalation or ‘chasing’) than when compared to pure heroin alone’.5 Heroin is also commonly adulterated  with paracetamol because the latter has approximately the same melting point as heroin and also has analgesic (pain-killing) properties. 

The Garda National Drugs Unit (GNDU) provided price data for 144 street-level heroin cases submitted to the FSL between 2010 and 2011. The powder weights for these packs ranged from 0.097g to 1.862g, with an average price per gram of €116.71. The most frequent street-pack prices were €20, €25 and €50. There was a correlation between pack sizes and prices, leading the authors to conclude that ‘the driving factor for diamorphine prices may not be perceived quality, but perhaps the quantity of drug sold, or customer demand in times of limited diamorphine supply’ (p.3). 

Findings in relation to cocaine seizures

In the NACDA/HRB study referred to above, a forensic analysis of 93 samples of cocaine found that purity levels were generally very low, averaging 14% across the four local drug markets studied. The current study, where purity was determined for 217 cocaine cases over the 2010–2012 period, made a similar finding, with the average purity remaining fairly stable, at 15% for 2010, 19% for 2011 and 17% for the first three months of 2012. The study also recorded a larger degree of variation in the purities of cocaine samples when compared to those for diamorphine. Ninety-nine per cent of samples contained one or more adulterants, with the main ones being lignocaine, levamisole, phenacetin, caffeine and benzocaine. According to Coomber (2006), referring to similar findings from research on the UK drug market, given that these are all substances that have either analgesic and/or stimulant properties, this shows the ‘purposive nature of such cutting’, or adulteration.6 Pricing data were obtained from the GNDU for 17 cocaine seizures for which purity was determined during the study period but no correlation was found between price and purity. 

When the findings of the study for 2010 were compared to similar data compiled by the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA), it was found that Ireland’s mean purity of diamorphine was the second highest after Turkey and that it ranked the third most expensive after Sweden and Latvia. With regard to cocaine data for 2010, it was found that the mean purity of cocaine in Ireland was the lowest reported to the EMCDDA, while the price per gram was the second highest after Luxembourg. 

The compilation and reporting of drug purity trend data in studies such as this can enhance our understanding of illicit drug markets and also the impact of drug law enforcement interventions on the behaviour of such markets. Studies such as this enable us to provide some context to changes in the behaviour of street-level drug markets. For example, it is worth speculating whether the decline in heroin purity since 2010 identified in this study may be linked to the heroin drought of that year, and also whether the poor quality of heroin may have contributed to the rise in the street sale and use of benzodiazepines by opiate users in recent years.7 

Comprehensive chemical profiling of drug seizures can also indicate links between seizures in different locations, thereby providing intelligence on patterns of drug supply. Information on the types of adulterants used to bulk up drugs for street sale and/or to enhance their quality for the end user can provide important public health information. At present, however, the purity of drugs in Ireland is not routinely tested (quantified) due to the resource implications such an endeavour would entail. The development and reporting of indicators in the drug supply area such as seizures, price and purity data are currently priorities of the EMCDDA, in collaboration with Europol and the European Commission.8


  1. Boyle M, Carroll L, Clarke K et al. (2014) What's the deal? Trends in Irish street-level heroin and cocaine 2010–2012. Drug Testing and Analysis, Published online 24 March. DOI: 10.1002/dta.1639. www.drugsandalcohol.ie/21608

2. Reuter P and Caulkins J (2004) Illegal ‘lemons’: price dispersion in cocaine and heroin markets. Bulletin on Narcotics, LVI, (1 & 2) 141–165. NewYork: United Nations Publications. www.unodc.org/pdf/bulletin/bulletin_2004_01_01_1_Art6.pdf

3. For further discussion of the role of adulterants in drug markets see Coomber R (2006) Pusher myths: re-situating the drug user. London: Free Association Press.

4. Connolly J and Donovan A (in press) Illicit drug markets in Ireland. Dublin: National Advisory Committee on Drugs and Alcohol, and Health Research Board. Some of the purity data from this study were reported in the following: Irish Focal Point (2011) 2011 National Report (2010 data) to the EMCDDA by the Reitox National Focal Point. Ireland: new developments, trends and in-depth information on selected issues. Dublin: Health Research Board. www.drugsandalcohol.ie/16812

5. Coomber R (2006) p. 73.

6. Coomber R (2006) p. 76.

7. Irish Focal Point (2011) 2011 National Report (2010 data) to the EMCDDA by the Reitox National Focal Point. Ireland: new developments, trends and in-depth information on selected issues. Section 1.2, p.20. Dublin: Health Research Board. www.drugsandalcohol.ie/16812

8. Connolly J (2011) First European conference on drug supply indicators. Drugnet Ireland, (36): 12. www.drugsandalcohol.ie/14696

Item Type
Publication Type
Irish-related, Open Access, Article
Drug Type
Cocaine, Opioid
Intervention Type
Crime prevention, Screening / Assessment
Issue Title
Issue 50, Summer 2014
July 2014
Page Range
pp. 22-23
Health Research Board
Issue 50, Summer 2014
Accession Number
HRB (Electronic Only)

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