While I am sure he addicts will still be in denial, I'll post this from the
National Institutes of Health:''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
In recent years, more attention has been given to drugs other than alcohol that have increasingly been recognized as hazards to road traffic safety. Some of this research has been done in other countries or in specific regions within the United States, and the prevalence rates for different drugs used vary accordingly.
Overall, marijuana is the most prevalent illegal drug detected in impaired drivers, fatally injured drivers and motor vehicle crash victims. Other drugs also implicated include benzodiazepines, cocaine, opiates, and amphetamines
..and this'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Why is Drugged Driving Hazardous?
Drugs acting on the brain can alter perception, cognition, attention, balance, coordination, reaction time, and other faculties required for safe driving. The effects of specific drugs of abuse differ depending on their mechanisms of action, the amount consumed, the history of the user, and other factors. MarijuanaTHC affects areas of the brain that control the body’s movements, balance, coordination, memory, and judgment, as well as sensations. Because these effects are multifaceted, more research is required to understand marijuana’s impact on the ability of drivers to react to complex and unpredictable situations. However, we do know that—
- A meta-analysis of approximately 60 experimental studies—including laboratory, driving simulator, and on-road experiments—found that behavioral and cognitive skills related to driving performance were impaired in a dose-dependent fashion with increasing THC blood levels.12
- Evidence from both real and simulated driving studies indicates that marijuana can negatively affect a driver’s attentiveness, perception of time and speed, and ability to draw on information obtained from past experiences.
- A study of over 3,000 fatally injured drivers in Australia showed that when marijuana was present in the blood of the driver, he or she was much more likely to be at fault for the accident. Additionally, the higher the THC concentration, the more likely the driver was to be culpable.13
- Research shows that impairment increases significantly when marijuana use is combined with alcohol.14 Studies have found that many drivers who test positive for alcohol also test positive for THC, making it clear that drinking and drugged driving are often linked behaviors.
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Find it here:
http://www.drugabuse.gov/publications/drugfacts/drugged-driving