"Apart from warnings issued against dangerous and unexpected pills, dosage makes a difference. In terms of neurotoxicity, several scientific studies pointed out that, among other factors, the probability for possible neurotoxic damage in the serotonergic system grows with the amount of MDMA being consumed. Therefore, most pill-testing projects inform potential consumers that they should not, if at all, consume more than 1,5–1,8 mg MDMA/kg bodyweight because of possible long-term damages to an important region of the brain. These messages, that are often followed by consumers of ecstasy, are only meaningful if consumers are in a position to have their pills chemically analysed. Otherwise they are unable to follow this or similar advice."


Kriener, Harald, Renate Billeth, Christoph Gollner, Sophie Lachout, Paul Neubauer, Rainer Schmid. An Inventory of On-Site Pill-Testing Interventions in the EU. Lisbon, Portugal: European Monitoring Centre for Drugs and Drug Addiction, 2001.