Heterogeneity in the composition of marijuana seized in California.
Marijuana contains multiple cannabinoids. Most attention is given to delta-9-tetrahydrocannabinol (THC) which produces euphoria and in some cases anxiety and panic reactions. Research suggests that another cannabinoid, cannabidiol (CBD), may offset some of these effects. Thus, there is growing interest in the health consequences of the THC to CBD ratio for marijuana. Using data from over 5000 marijuana samples in California from 1996 to 2008, we examine changes in the median THC-level, median CBD-level, and median THCCBD-ratio. The median THC-level and median THCCBD-ratio have dramatically increased for seizures in California, particularly north of the Mexican border. Research on the consequences of the THCCBD ratio should continue, especially as more attention is devoted to thinking about how to regulate marijuana for medical and recreational use. Researchers should also consider the lack of uniformity in the chemical composition of marijuana when evaluating its health effects.