Many urban legends and misconceptions about drugs have been created and circulated among young people and the general public, with varying degrees of veracity. These are commonly repeated by organizations which oppose all classified drug use, often causing the true effects and dangers of drugs to be misunderstood and less scrutinized. The most common subjects of such false beliefs are LSD, cannabis, and MDMA. These misconceptions include misinformation about adulterants or other black market issues, as well as alleged effects of the pure substances.