Marijuana safer than drink, says crash study, The Advertiser
If alcohol could be replaced by marijuana it would be a major road safety advance, one of Australia's leading road safety specialists claims...
Cannabis cleared in report on road toll, The Australian (undated)
Motorists who use Cannabis are no more likely to be involved in a fatal collision than drivers who are drug free, a study by the Victorian Institute of Forensic Pathology says...
Drink, not Cannabis causes road deaths LTE by Dr Alex Wodak, The Australian
Marijuana's Effects on Actual Driving Performance by HWJ Robbe, Institute for Human Psychopharmacology, University of Maastricht, The Netherlands
(A paper presented at the 13th International Conference on Alcohol, Drugs & Traffic Safety, Adelaide SA. )
Cannabis & Driving by Dr Greg Chesher
[email protected]
Colleagues,
I want to mention the present understanding about Cannabis and driving. You may already be quite familiar with these studies, but in case you are not, the following might interest you. The law about alcohol which proscribes driving with BAC >0.05 g% blood alcohol has been determined by epidemiological studies employing the case-control method. At 0.05g% the driver is about twice as likely to be involved in a crash as a driver with zero BAC. As the BAC increases, so in a very steep fashion, does the probability of being involved in a crash. The role of alcohol in road crashes has been very clearly demonstrated. The drink-driving laws are based upon sound science!
As for other drugs, including Cannabis, the pharmacokintetics do not permit this technique. There is no correlation between the blood concentration of Cannabinoids and impairment as determined on laboratory tasks. Furthermore, the study would require the taking of blood from the crash involved drivers as well as that of the control drivers--not involved in a crash. There is no equivalent to the alcohol breathalyser. Cannabinoids are not excreted on the breath. (It is the collection of adequate data from a control group that really precludes the case-control method). So to overcome this, the technique of "culpability analysis" has been employed.
In this case, data for crashes are presented to an independent group of observers who are ignorant (blind) as to whether any of the drivers had any drug at all in their blood. By studying the information of the crash (events before and up to the crash) a score apportioning the degree of blame to each driver is given. From this "culpability" is determined.
So far there have been four studies using this technique, two in the USA and two in Australia.
As far as Cannabis is concerned, it is quite remarkable that in all cases the results were so similar as to be the same finding. The culpability ratio for the drivers bearing Cannabinoids in blood revealed that they were no more likely to be considered as a cause of the crash as those who had no drugs at all in their blood. Indeed in each of these four studies the Cannabinoid drivers were less (but not significantly so) likely to have been a cause than those with no drug at all. In all of these studies alcohol-bearing drivers were overwhelmingly culpable.
So at the moment, the present data suggest that cannabis is not involved as a causative factor in road crashes.
Two things must be considered. First, it is early days so far. The total number of cases in all of these studies totals about 9000 or a little less.
Second, the determination of the culpability score is dependent upon the integrity of the initial data describing the accident. In most cases this is from the attending police. This is not always reliable. However, as the numbers increase with more studies, we will have more confidence with the findings.
There is another Australian study currently being analysed and is due to be released shortly.....SOON is the advice I have from the author.
Cheers,
Greg Chesher
References
Drummer, O. (1994). Drugs and drivers killed in Australian Road traffic accidents. The use of responsibility analysis to investigate the contribution of drugs to fatal accidents: Victorian Institute of Forensic Pathology. Monash University.
Hunter, C., Lokan, R., Longo, M., White, J. & White, M. (1998). The Prevalence and Role of Alcohol, Cannabinoids, Benzodiazepines and stimulants in Non-Fatal Crashes. Adelaide: Forensic Science, Department for Administrative and Information Services, South Australia.
Terhune, K., Ippolito, C., Hendricks, D., Michalovic, J., Bogema, S., Santinga, P., Blomberg, R. & Preusser, D. (1992). The incidence and role of drugs in fatally injured drivers.: US Department of Transportation National Highway Traffic Safety Administration.
Williams, A., Peat, M., Crouch, D., Wells, J. & Finkle, B. (1985). Drugs in fatally injured young male drivers. Public Health Reports, 100, 19-25
Dr Gregory B. Chesher
ALCOHOL IMPAIRS DRIVING MORE THAN MARIJUANA
A single glass of wine will impair your driving more than smoking a joint. And under certain test conditions, the complex way alcohol and cannabis combine to affect driving behaviour suggests that someone who has taken both may drive less recklessly than a person who is simply drunk.
These are the findings of a major new study by British transport researchers. The unpublished research, seen exclusively by New Scientist, stops well short of condoning driving under the influence of even small amounts of cannabis. But in a week which has seen renewed debate in Britain surrounding the criminalisation of cannabis, it throws an uncomfortable spotlight on a problem confronting governments everywhere - how to deter the growing numbers of cannabis users from "dope driving".
At present there is no accurate test that can reveal whether a driver has taken cannabis before driving, and developing one will not be easy. But even when this problem is cracked, another will remain - where to set the safety threshold for smoking cannabis.
Advocates of zero tolerance say there should be penalties for drivers caught with any amount of recently smoked cannabis in their body. The new research suggests that would only be credible if governments also adopted zero tolerance on drink driving.
Middle Of The Road
The new study was undertaken by the Transport Research Laboratory in Crowthorne, Berkshire, and confirms the results of a preliminary study more than a year ago. Researchers at the TRL, led by Barry Sexton, gave 15 volunteers doses of cannabis or alcohol, or a combination of both, before letting them loose on an array of psychomotor tests and a sophisticated driving simulator.
The volunteers were given either enough alcohol to raise alcohol levels in the blood to 50 milligrams per 100 millilitres - about 60 per cent of Britain's legal limit of 80 mg/100 ml - or a specially prepared marijuana joint designed to deliver the same high typically experienced by smokers.
In the study, cannabis significantly affected only one criterion, known as tracking ability. Volunteers found it more difficult to hold a constant speed and follow the middle of the road accurately while driving around a figure-of-eight loop. The TRL researchers point out in their draft report that this test requires drivers to hold their concentration for a short time, a task which is particularly badly affected by the intoxicating effects of cannabis.
Cautious Driving
However, volunteers drinking the equivalent of a glass of wine fared worse than those who had smoked a joint. Those who were given both alcohol and cannabis performed worse still, reinforcing the idea that alcohol has a cumulative effect when taken with other drugs.
But the study also found that drivers on cannabis tended to be aware of their intoxicated state, and drove more cautiously to compensate. Indeed, doped-up volunteers often rated themselves as being more impaired than police surgeons brought in to evaluate their sobriety.
Surprisingly, drinking alcohol didn't offset this cautious behaviour, opening up the unproven possibility that a driver who is moderately drunk might be better off under some conditions if they had also smoked.
This cautious behaviour is in line with findings by other researchers. "Whereas alcohol promotes risk taking like fast speeds and close following, cannabis promotes conservative driving, but may cause attention problems and misperceptions of time," says Nicholas Ward, technical adviser to the Immortal project - a three-year European Union trial designed to quantify the crash risk drivers face after taking various drugs and medicines.
![:\](https://bluelight.org/xf/BL_Images/Orig_Emoji/wrygrin.gif "wry grin :\")
