"Data show that there was a large decrease in the average purity of heroin in 2011 (Table 10.8). This follows reports of a reduction in the availability of heroin from late 2010 both within the international supply chain and within the UK. Indeed, the number of seizures the purity data in Table 10.8 is based on decreased by almost one-third in 2011 and seizures data also show a decrease in the quantity of heroin seized in 2010/11 (see section 10.3.2). Despite reports of a reduction in the supply of heroin and an increase in the wholesale price, the street-level price of heroin, as reported by law enforcement agencies, decreased from £45 per gram to £40 per gram. However, when adjusting for purity, the price of heroin increased significantly from £42.16 to £74.32 (Table 10.9). This suggests that dealers are more likely to adulterate their product in times of shortages than increase the price as indicated in research studies (Matrix Knowledge Group 2007). Street-level heroin is commonly adulterated with both caffeine and paracetamol."


UK Focal Point on Drugs, "United Kingdom Drug Situation 2012 Edition: Annual Report to the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA)" (London, England: UK Government, Department of Health, October 31, 2012), p. 183.