As this review shows, no convincing experimental or clinical evidence exists to prove that the commonly used dosages of pure LSD produce genetic mutations, congenital malformations or malignant growths. As far as illicit LSD is concerned, the situation is much more complex, and the results of the studies of illicit LSD users should not be considered relevant to the question of the biological dangers of LSD. Uncertainties about the dosage, and the contamination of black-market samples of psychedelic drugs by various impurities and additives contribute a very important dimension to the already serious psychological hazards associated with unsupervised self-experimentation.
There is absolutely no indication in the research data currently available that responsible experimental and therapeutic use of LSD by experienced professionals should be discontinued.