8. Marijuana is more potent today than in the past

This myth is the result of bad data. The
researchers who made the claim of increased potency used
as their baseline the THC content of marijuana seized by
police in the early 1970s. Poor storage of this marijuana in
un-air conditioned evidence rooms caused it to deteriorate
and decline in potency before any chemical assay was
performed. Contemporaneous, independent assays of
unseized "street" marijuana from the early 1970s showed a
potency equivalent to that of modern "street" marijuana.
Actually, the most potent form of this drug that was generally
available was sold legally in the 1920s and 1930s by the pharmaceutical
company Smith-Klein under the name, "American Cannabis".