impaired

The existence of hallucinations, delusions, and organic brain dysfunction in heavy cannabis users seems to be associated with cannabinoid levels in hair. The continuation of persistent symptoms 3 months after the discontinuation of cannabis abuse, was a remarkable finding. SCIENTIFIC SIGNIFICANCE: We provide evidence that chronic and heavy cannabis abuse results in long-lasting brain dysfunction in all users and in long-lasting schizophrenia-like psychotic symptoms in more than half of all users. These findings suggest a reevaluation of the current classification of cannabis as a "soft narcotic" which erroneously, therefore, is typically considered harmless. (Am J Addict 2017;XX:1-8).

THC is a large, fat-soluble molecule whose concentration in the blood rapidly drops as it is sequestered into the body’s fat stores, including the brain.  Immediately after smoking a joint, the THC level will be very high in the blood and very low in the brain.  The THC level in the brain climbs rapidly at the same time that as it is declining in the blood.  At some point, the concentrations cross, and the concentration continues to rise in the brain while it is still declining in the blood, since the brain acts like a sponge, soaking up the partially insoluble THC from the blood.  

A National Institute on Drug Abuse study tasked stoned participants with driving a highly sophisticated driving simulator.
 
Researchers found that after their blood levels of THC reached a certain point, the drivers weaved similarly to a driver with a BAC of .08
 
The study also found that combining cannabis and alcohol decreased motor skills even more than just one or the other 

 Russell admitted he had smoked marijuana at lunch and again as he drove to pick up his children in Brodhead, the criminal complaint indicates.“All I did was smoke a bowl of marijuana. It's not like I am high,” Russell is quoted as saying in the criminal complaint.“The defendant did not seem to understand that smoking marijuana and driving were illegal,” the complaint states

#no2pot

Overall, traffic fatalities in Colorado decreased 14.8 percent, from 2007 to 2012. During the same five years in Colorado, traffic fatalities involving operators testing positive for marijuana increased 100 percent.

In 2007, Colorado traffic fatalities involving operators testing positive for marijuana represented 7.04 percent of the total traffic fatalities.  By 2012, that number more than doubled to 16.53 percent.

During the last three years, Metro's forensics lab screened 4,500 blood samples for marijuana with the bulk of those being impaired drivers.
Metro said marijuana is dangerous because it slows down mental reactions and a driver's judgment of time and distance. Statewide records from 2002 to 2012 show 45 percent of drivers who were impaired by drugs had marijuana in their system.

Marijuana does possess certain medicinal properties. So does opium. But we don’t allow unscrupulous quacks to write raw opium prescriptions for anyone willing to pay $65. And if we did, would anybody be surprised that the vast majority of opium buyers were not recovering from surgery—and that many of them shared or resold some of their opium to underage users?