Marijuana (cannabis) is the most frequently used illicit drug of abuse in the United States and worldwide. Moreover, it is second only to alcohol as the most prevalent psychoactive substance seen in cases of driving under the influence of drugs. It is also by a wide margin, the drug most often detected in workplace drug-testing programs. The primary psychoactive substance in marijuana is delta-9-tetrahydrocannabinol, known simply as THC. Present in steadily increasing concentrations in street-purchased, smokeable plant material, the THC content in marijuana averaged 3% in the 1980s, but by 2012 it had increased to 12%. (Read entire article)
