"Nutt et al. (2007) attempted to compare the relative dangers of the main types of psychosocial drug, using a series of subjective rating scales. Heroin and cocaine were graded as the two most harmful drugs, whereas Ecstasy/MDMA emerged as one of the least harmful (18th out of 20). Unfortunately, it was unclear how this low harm rating score for Ecstasy/MDMA was given, as they cited no empirical research studies or reviews. Instead, Nutt et al. (2007) suggested that: ‘for drugs which have only recently become popular e.g. Ecstasy or MDMA, the longer term health and social consequences can only be estimated from animal toxicology at present’. Nutt et al. (2007) noted that the most pleasurable drugs tended to be the most problematic, and on the ‘intensity of pleasure’ scale, heroin and cocaine were given maximum scores of 3.0. In contrast, Ecstasy/MDMA was given an ‘intensity of pleasure’ score of 1.5, which was lower than cigarette smoking at 2.2. It is unclear why Ecstasy was rated as less pleasurable than smoking a cigarette, although the low pleasure score contributed to its low harm score.
"Another question concerned drug injections, with Nutt et al. (2007) noting that ‘The potential for intravenous use is taken into account in the Misuse of Drugs classification and was treated as a separate parameter in our exercise’. Cocaine and heroin were given maximum scores of 3.0, whereas Ecstasy/MDMA was given a score of 0. Again, this did not accord with the empirical literature. In their survey of 329 recreational Ecstasy/MDMA users, Topp et al. (1999) reported that 54 (16%) had injected Ecstasy. MDMA injecting may be atypical and only occurs amongst the more experienced Ecstasy users, although this pattern would also describe cocaine. Most cocaine users never inject, and it is only found with experienced users. Hence, the injection score for MDMA should be similar to that for cocaine. Many of the other Ecstasy harm values in Nutt et al. (2007) were surprisingly low. With revised values based on the empirical literature, MDMA rises to the fifth most harmful drug (Parrott, 2009b)."
Parrott, Andrew C., "Human Psychobiology of MDMA or 'Ecstasy': An Overview of 25 Years of Empirical Research," Human Psychopharmacology: Clinical and Experimental, 2013; 28:289-307. DOI: 10.1002/hup.2318