RE: Cannabis Risk
Wednesday 29th May 2002
Cannabis Risk
Police are concerned that the reclassification of cannabis will lead to more crashes on the roads. Around 30% of accidents are down to alcohol and around 20% are drug related already. If a blind eye is turned to cannabis use then this figure may rise.
Discussion
I look up when i get a min and if can find them again
Ill post them here.
There were some tests done here in the uk and downunder that on driving after a smoke
they did not really like the results so keep it a it hush hush.
ie it seem to make most more carefull drivers.
un like alcohol.
they had the same results in oth tests.
SEE ABOVE THE TREADS STONED AND THE POSTS ARE GOING IN THE WROUGN PLACE.
>> Edited by outlaw on Wednesday 29th May 21:06
Ill post them here.
There were some tests done here in the uk and downunder that on driving after a smoke
they did not really like the results so keep it a it hush hush.
ie it seem to make most more carefull drivers.
un like alcohol.
they had the same results in oth tests.
SEE ABOVE THE TREADS STONED AND THE POSTS ARE GOING IN THE WROUGN PLACE.
>> Edited by outlaw on Wednesday 29th May 21:06
quote:
Are they suggsting that 50% of accidents are caused by Alcohol and Drugs..
..but what about speed (no not amphetamine), we all know that speed is the main cause of accidents..
Ah, but I think that you will find that 90% of accidents are caused by excessive speed, a further 50% by drunk or drugged drivers and then even 35% by inexperienced drivers - I havent even mentioned the 25% for company car drivers too....
Then again 29% of all statistics are made up on the spot.
To be honest it is yet another example of the poor testing / statistics / maths of the people that publish such figures. There is no one single centre for this information (unless it is the ONS and they arent telling) and as a result all of the various groups are manipulating the figures for their own benefit.
Interesting if on the other thread that speed cameras reduced accidents by 20% - so lets get this right - if 50% of drivers are drunk or drugged then that is a pretty serious reduction in speeders - I THINK NOT!!!
Liar liar pants on fire
Cheers,
Paul
whilst the figures are undoubtedly the normal toss touted around to make up for a complete lack of facts, the sentiment is good.
Cannabis smoking DOES lead to decreased perception, awareness or frankly giving a toss (except for chocolate and crisps). In the same way alcohol DOES impair coordination, reduce responses and make people think they're better than they are.....
I would think it fair to say that there are lots of people on the roads who are safer drivers p*ssed than the majority are sober...but that isn't the point. We all feel curently that we are better enough than average that the 'numptie speed limit' shouldn't really apply to us. It isn't really there for us anyway - it's for the average driver (and obviously has to be aplplied equally). This also applies to alcohol and drugs of all sorts.... Pot affects different people different ways....some it sends to sleep in fairly short order....wouldn't really want to share a road with one of them.
Carzee...think of the worst driver you know personally...now imagine them well and truly stoned...fancy your wife/lover/family driving the other way on a dark, wet night?
thoughts? comments? abuse? BRING IT
Night
Cannabis smoking DOES lead to decreased perception, awareness or frankly giving a toss (except for chocolate and crisps). In the same way alcohol DOES impair coordination, reduce responses and make people think they're better than they are.....
I would think it fair to say that there are lots of people on the roads who are safer drivers p*ssed than the majority are sober...but that isn't the point. We all feel curently that we are better enough than average that the 'numptie speed limit' shouldn't really apply to us. It isn't really there for us anyway - it's for the average driver (and obviously has to be aplplied equally). This also applies to alcohol and drugs of all sorts.... Pot affects different people different ways....some it sends to sleep in fairly short order....wouldn't really want to share a road with one of them.
Carzee...think of the worst driver you know personally...now imagine them well and truly stoned...fancy your wife/lover/family driving the other way on a dark, wet night?
thoughts? comments? abuse? BRING IT
Night
I agree with the point that you do have to blanket law everyone regardless of ability and cater for a lowest common denomenator.
The differentiation between marijuana and alcohol however is that there is only a very very very low incidence of paranoia in drivers under the influence of alcohol whereas its quite prevalent in stoned drivers.
Alcohol leads to feel indestructible whereas pot is th e opposite. I believe that Outlaws study that he is trying to find will support this.
In Holland I dont know what measures they have invoked to combat this but in 25 years of legalisation there hasnt really been any breaking news that due to de-criminalisation road accidents went up.
Matt.
The differentiation between marijuana and alcohol however is that there is only a very very very low incidence of paranoia in drivers under the influence of alcohol whereas its quite prevalent in stoned drivers.
Alcohol leads to feel indestructible whereas pot is th e opposite. I believe that Outlaws study that he is trying to find will support this.
In Holland I dont know what measures they have invoked to combat this but in 25 years of legalisation there hasnt really been any breaking news that due to de-criminalisation road accidents went up.
Matt.
quote:Yes Night, I can.. but to emote rather than actually think is at the core of all that is wrong with our 'safety' culture...
Carzee...think of the worst driver you know personally...now imagine them well and truly stoned...fancy your wife/lover/family driving the other way on a dark, wet night?
And when I actually *think* about it - I'm entirely unworried. My wife is a good, competent driver, who knows what to expect from every other moron on the road. ie Nothing but poor driving and cerebral inadequacy. she drives accordingly (very fast to get away from them
). Whilst I agree that smoking dope and driving is incredibly stupid. I feel that the thought declassification would increase accidents is b*ll*cks. So many people already use drugs, declassification is not going to suddeenly make people go "oh I must be okay to drive stoned then"
The reason that Canabis is being declasified is because so many people participate and it makes no sense when compared to drink and tabacco (ie both of these are more hazardous than canabis). Thank goodness in my book that at last some legislation might be produced that makes sense.
Also this statistic about drugs doesn't mention other legal drugs that people have been prescribed and driven whilst taking (some of those seriously affect judgement). I would suspect that there are more people driving on those kind than Canabis.
The reason that Canabis is being declasified is because so many people participate and it makes no sense when compared to drink and tabacco (ie both of these are more hazardous than canabis). Thank goodness in my book that at last some legislation might be produced that makes sense.
Also this statistic about drugs doesn't mention other legal drugs that people have been prescribed and driven whilst taking (some of those seriously affect judgement). I would suspect that there are more people driving on those kind than Canabis.
I wouldn't be surprised if there was a small rise in stoned accidents. People are _that_ stupid. However, I see no reason why this would persist for any length of time. You'd expect society to take a while to get used to handling this new "freedom" sensibly. Either way, a bit of extra traffic risk pales into insignificances compared to the benefit of denying drugs dealers some cash
(only jokin i might add!) 
[
good oh - somehing I can actually disagree with you on! I have no doubt at all that some aspects of society are framed and formed due to emotion getting the better part of sense...however this isn't one of those times. I wasn't suggesting for a minute that 'all the poor widdle lambikins might be in danger' - I dont have morals, a conscience or much in the way of emotion as it goes. Your point about your wife is sadly irrelevant. The best driver I have ever known was killed near me when someone overtook, on a blind bend up a hill and hit him head on. There wasn't a damn thing he could do about it - good, bad or indifferent. The driver was w*nkered - undoubtedly clouding his judgement on this particular manouver, even if it didn't impair his driving ability - who knows?
yeah - stoned people tend to drive slower and more carefully cos they're well aware that they're a bit gone...however until a 'crisis' arises they will never know how far gone they are - and that could make the difference. It is (allegedly) quite easy to sit and smoke a few joints, feel fairly normal, then get up......and suddenely realise just how whacked you are. On a car journey a very similar mis-judged 'comfort' zone could easily arise.
I aint saying being stoned makes you a bad driver...or that being p*ssed, on a mobile, smoking a fag, changing a tape, talking to your passenger, doing handbrake turns, topping 140 or anything else does either. but seeing as I think about 70% of the general public should ALREADY be off the roads, god help us when they're out of it as well!!
cheers
Night
quote:
Yes Night, I can.. but to emote rather than actually think is at the core of all that is wrong with our 'safety' culture.... My wife is a good, competent driver, who knows what to expect from every other moron on the road (note cunning paraphrasing)
good oh - somehing I can actually disagree with you on! I have no doubt at all that some aspects of society are framed and formed due to emotion getting the better part of sense...however this isn't one of those times. I wasn't suggesting for a minute that 'all the poor widdle lambikins might be in danger' - I dont have morals, a conscience or much in the way of emotion as it goes. Your point about your wife is sadly irrelevant. The best driver I have ever known was killed near me when someone overtook, on a blind bend up a hill and hit him head on. There wasn't a damn thing he could do about it - good, bad or indifferent. The driver was w*nkered - undoubtedly clouding his judgement on this particular manouver, even if it didn't impair his driving ability - who knows?
yeah - stoned people tend to drive slower and more carefully cos they're well aware that they're a bit gone...however until a 'crisis' arises they will never know how far gone they are - and that could make the difference. It is (allegedly) quite easy to sit and smoke a few joints, feel fairly normal, then get up......and suddenely realise just how whacked you are. On a car journey a very similar mis-judged 'comfort' zone could easily arise.
I aint saying being stoned makes you a bad driver...or that being p*ssed, on a mobile, smoking a fag, changing a tape, talking to your passenger, doing handbrake turns, topping 140 or anything else does either. but seeing as I think about 70% of the general public should ALREADY be off the roads, god help us when they're out of it as well!!
cheers
Night
Let just get It clear before I post, I got nothing against a spliff, but I hate the stuff my self and dont smoke it.
however I do belive all drugs should be legalised
inludind hard drugs for all adults.
It would save a foutuen each year pluss if they any one wants to spend there life in a druged up haze or kill there selfs. Thats there porblem, no one else. so I say let em get on with it.
But heres the Conclusion, you can find the whole lot here:
www.roads.dtlr.gov.uk/roadsafety/cannabis/
aparently the dint like the test results much
"
Department of the Environment,
Transport and the Regions
Cannabis and Driving:
A Review of the Literature and Commentary
--------------------------------------------------------------------------------
CHAPTER 11
Conclusion
This report has summarised available research on cannabis and driving. The report has included the main review documents for research published before 1994 (e.g., Hall et al., 1994; Robbe, 1994) as well as primary sources for research published from 1994 using keyword searches of relevant databases. This synthesis of research was directed to identify key research objectives to develop a rational transport policy for cannabis and driving.
It is apparent that cannabis is the most common 'illicit' drug. Indeed, there is some evidence to indicate an increasing trend in its availability and use in the general population. Thus, in terms of drug use and traffic safety, this would suggest that cannabis represents the major drug type to be addressed by transport safety policy.
However, there is not sufficient evidence indicating the percentage of drivers that operate a vehicle after consuming cannabis, particularly during the time period of any intoxicating effect. As a result, there is no precise estimate of the percentage of drivers exposed to cannabis as an accident risk factor. Indeed, it is problematic to estimate the extent of exposure independent of other risk factors associated with cannabis use such as alcohol. Moreover, the demographic group most frequently using cannabis already has the greatest a priori accident risk due to driving inexperience and factors associated with youth relating to risk taking, delinquency and motivation. These demographic and psychosocial variables may relate to both drug use and accident risk, thereby presenting an artificial relationship between use of drugs and accident involvement.
The recent developments and discoveries in pharmacology such as cannabinoid receptors and endogenous ligands are important and exciting. These and the increased understanding of the mechanism of action of cannabis will mean that new or improved methods of detection are likely. Most promising to date in terms of reliability, detection of recent consumption and practical application are methods for determining presence of metabolites in saliva and sweat. These developments and ongoing research also have implications for therapeutic drug development. New compounds based on cannabinoids will need careful evaluation to confirm their lack of psychoactive and psychomotor effects.
Evidence of impairment from the consumption of cannabis has been reported by studies using laboratory tests, driving simulators and on-road observation. The laboratory tests generally indicate acute impairment of memory, attention and psychomotor control. Both simulation and road trials generally find that driving behaviour shortly after consumption of larger doses of cannabis results in (i) a more cautious driving style; (ii) increased variability in lane position (and headway); and (iii) longer decision times. Whereas these results indicate a 'change' from normal conditions, they do not necessarily reflect 'impairment' in terms of performance effectiveness since few studies report increased accident risk. However, the results do suggest 'impairment' in terms of performance efficiency given that the increased compensatory effort resulting from cannabis use limits the available resources to cope with any additional, unexpected or high demand, events.
In conclusion, cannabis impairs driving behaviour. However, this impairment is mediated in that subjects under cannabis treatment appear to perceive that they are indeed impaired. Where they can compensate, they do, for example, by not overtaking, by slowing down and by focusing their attention when they know a response will be required. However, such compensation is not possible where events are unexpected or where continuous attention is required. Effects of driving behaviour are present up to an hour after smoking but do not continue for extended periods.
"With respect to comparisons between alcohol and marijuana effects, these substances tend to differ in their effects. In contrast to the compensatory behaviour exhibited by subjects under cannabis treatment, subjects who have received alcohol tend to drive in a more risky manner. Both substances impair performance, however, the more cautious behaviour of subjects who have received cannabis decreases the impact of the drug on performance, where the opposite holds true for alcohol." (Smiley, 1998, p. 19)
It is notable that the studies based on laboratory tests tend to indicate more effects of cannabis consumption than those using simulation and road observation methods. The higher incidence of effects under laboratory test conditions relative to the 'natural' conditions of simulation and road studies has been attributed to (i) reduced error variance from greater control of test conditions; (ii) higher task demand under novel test conditions; (iii) irrelevance or non-equivalence of laboratory test to component of driving; (iv) greater latitude for compensatory effort under 'natural' conditions; and (v) self-selection under 'natural' conditions not to be exposed to risk (e.g., not drive).
"It is exceedingly difficult to explain the disparity in results obtained by laboratory tests and in driving situations. Rather than try, it seems better for the moment to assume that both sets of results are valid for the particular circumstances under which they were obtained. It demonstrates, however, that performance decrements obtained under the artificial and non-life threatening conditions in the laboratory do not automatically predict similar decrements in driving situations that are closer to real-world driving." (emphasis added, Robbe, 1994, p. 66).
The greater propensity for cannabis effects under laboratory test conditions is somewhat paradoxical given that the laboratory tests have typically used smaller doses of cannabis than the simulation and road studies. It is also controversial since the limited number of studies and absence of demonstrable effects under natural driving conditions has impeded the development of transport policy regarding cannabis use. Whereas evidence of drug impairment under laboratory test conditions is not sufficient to provide an increase in accident risk, it does demonstrate cause for concern. This concern should then guide subsequent research under simulation and road conditions to investigate more valid evidence of impairment. Such efforts should be guided by relevant laboratory tests that relate to a model of driving, and use of a standard test methodology and reporting format for both simulation and road based research. This will provide a logical sequence of inquiry that can include both the replication of key findings, and the comparison of effects between a range of study designs.
Attempts to estimate the accident risk associated with cannabis use have relied on epidemiological evidence from accident involved drivers. Whereas this evidence has identified the presence of cannabis amongst accident involved drivers, accident risk can not be calculated given the absence of valid baseline data for cannabis detected in the non-involved population. Moreover, the presence of cannabis is often confounded by alcohol, as well as demographic and psychosocial risk factors associated with both drug and alcohol use. Current methodologies can only determine the presence of cannabinoids, but not evidence of impairment.
Thus, not only is it problematic to estimate the percentage of accident involvements associated with cannabis use alone, there is no evidence that impairment resulting from cannabis use causes accidents. Attempts to alleviate these problems by calculating risk of culpability for an accident (rather than the risk of having an accident) suggest that cannabis may actually reduce responsibility for accidents. It is evident that further epidemiological research is necessary. Such research must adopt a 'Grand Rapids' methodology of obtaining valid baseline data matched to positive cases, as well as including sufficient sample sizes and a valid operational definition of 'responsibility'. Such research may benefit from differentiating between accident types and accounting for relevant covariates including driver age and sex.
Much of the interest in cannabis as a potential accident risk factor is related to the concern about alcohol. Both alcohol and cannabis have an intoxicating effect that alters the psychological state of the individual. However, the mechanism of action and form of intoxication of these drugs are distinct. Alcohol may provide a useful metric to evaluate the effect of cannabis. Moreover, given the existence of a set legal limit for alcohol, research of the dose equivalence between alcohol and cannabis for performance relevant to accident risk may provide a method of determining a safety critical limit for cannabis. German research based on meta-analyses has concluded that 50% of performance is impaired at 11ng/ml THC, making this an equivalent level of intoxication to 0.08% BAC, although more recent and driving specific studies need to be compared with respect to effect size to confirm these suggested dose equivalences.
However, it is important not to use parallel reasoning between alcohol and cannabis to dictate the research agenda and transport policy for cannabis alone. Such reasoning is particularly inappropriate for medicinal applications of cannabis derivatives.
"There has developed an understandable but regrettable tendency to separate alcohol from other impairing agents and at the same time to enact tough drugs-driving legislation which remains firmly based on experience with alcohol. This is illogical, inappropriate and usually quite unenforceable. There is often pressure to define, for legal purposes, critical body fluid concentrations above which all would be impaired and below which no impairment would be demonstrable. At present, this is not possible. In addition to the considerably more complex pharmacokinetic and pharmacodynamic effects of most drugs compared with those of ethanol, there is also the proposition that therapeutic drugs, used for legitimate purposes, may improve the driving ability of certain patients despite their ability to impair performance normal individuals." (Starmer et al., 1988, p. 35-36)
One approach to deriving a legal limit for cannabis during driving has been to set the threshold to the level at which 50% of results show impairment. For alcohol, Berghaus showed a BAC of 0.073% corresponded to impairment on 50% of 923 performance measures examined. The corresponding threshold for THC was 11ng/ml. This is the closest estimate of dose equivalence to date, although there are recent, well-controlled studies which have not been included in such meta-analyses. A necessary research undertaking would be a thorough meta-analysis of results to date, using statistical measures of effect size related to dose.
An alternative is to specify a zero limit threshold, where any level of detected drug is prohibited. However, such an approach is premised on the philosophy that any drug which alters the state of the driver is inconsistent with the responsibility of the driver to operate the vehicle only when in an optimal state. This approach is associated with its own impracticalities of defining an 'optimal' state and deciding if reasons for impairment (i.e. deviation from the optimal state) other than drug use can be prosecuted (e.g., fatigue, poor driving skills, age related decline in capacity to drive etc.).
Ultimately, the direction of transport policy will be decided by an assignment of relative priorities. On one hand, any drug that affects the alertness and capability of a driver to safely operate a vehicle must be precluded. On the other hand, there are other factors such as alcohol which have a stronger association with accidents.
"Of the many psychotropic drugs, licit and illicit, that are available and used by people who subsequently drive, cannabis may well be amongst the least harmful. Campaigns to discourage the use of cannabis by drivers are certainly warranted. But concentrating a campaign on cannabis alone may not be in proportion to the safety problem it causes" (Robbe, 1994, p. 177).
The main conclusion from this report is that there is insufficient evidence of the accident risk associated with cannabis. Future research directed to the formulation of transport policy is required to resolve many key issues that remain unresolved in relation to cannabis and driving. However, it must be recognised that these issues may not be readily resolved given the ethical, legal, and technical impediments of the research domain (Hall et al., 1994).
This call for additional research was set forth by Robbe at the conclusion of his oft cited treatise on cannabis and driving:
"This dissertation should not be considered as the final word. It should, however, remain for a while as a point of departure for subsequent studies that will ultimately complete the picture of cannabis effects on driving performance" (p. 177).
It is now imperative that funding is made available to facilitate further research. However, such research must also be supported by mechanisms to accommodate legal and ethical requirements in this area. "In the meantime, cannabis users should be urged not to drive while intoxicated by cannabis, and they should be particularly warned of the dangers of driving after combining both alcohol and cannabis" (Hall et al., 1994, p. 50)."
how the the bloody hell did thispost end up in the middel of the tread.
weird man I think the bulitin board soft wares had a few spliffs. :-)
>> Edited by outlaw on Wednesday 29th May 20:55
however I do belive all drugs should be legalised
inludind hard drugs for all adults.
It would save a foutuen each year pluss if they any one wants to spend there life in a druged up haze or kill there selfs. Thats there porblem, no one else. so I say let em get on with it.
But heres the Conclusion, you can find the whole lot here:
www.roads.dtlr.gov.uk/roadsafety/cannabis/
aparently the dint like the test results much
"
Department of the Environment,
Transport and the Regions
Cannabis and Driving:
A Review of the Literature and Commentary
--------------------------------------------------------------------------------
CHAPTER 11
Conclusion
This report has summarised available research on cannabis and driving. The report has included the main review documents for research published before 1994 (e.g., Hall et al., 1994; Robbe, 1994) as well as primary sources for research published from 1994 using keyword searches of relevant databases. This synthesis of research was directed to identify key research objectives to develop a rational transport policy for cannabis and driving.
It is apparent that cannabis is the most common 'illicit' drug. Indeed, there is some evidence to indicate an increasing trend in its availability and use in the general population. Thus, in terms of drug use and traffic safety, this would suggest that cannabis represents the major drug type to be addressed by transport safety policy.
However, there is not sufficient evidence indicating the percentage of drivers that operate a vehicle after consuming cannabis, particularly during the time period of any intoxicating effect. As a result, there is no precise estimate of the percentage of drivers exposed to cannabis as an accident risk factor. Indeed, it is problematic to estimate the extent of exposure independent of other risk factors associated with cannabis use such as alcohol. Moreover, the demographic group most frequently using cannabis already has the greatest a priori accident risk due to driving inexperience and factors associated with youth relating to risk taking, delinquency and motivation. These demographic and psychosocial variables may relate to both drug use and accident risk, thereby presenting an artificial relationship between use of drugs and accident involvement.
The recent developments and discoveries in pharmacology such as cannabinoid receptors and endogenous ligands are important and exciting. These and the increased understanding of the mechanism of action of cannabis will mean that new or improved methods of detection are likely. Most promising to date in terms of reliability, detection of recent consumption and practical application are methods for determining presence of metabolites in saliva and sweat. These developments and ongoing research also have implications for therapeutic drug development. New compounds based on cannabinoids will need careful evaluation to confirm their lack of psychoactive and psychomotor effects.
Evidence of impairment from the consumption of cannabis has been reported by studies using laboratory tests, driving simulators and on-road observation. The laboratory tests generally indicate acute impairment of memory, attention and psychomotor control. Both simulation and road trials generally find that driving behaviour shortly after consumption of larger doses of cannabis results in (i) a more cautious driving style; (ii) increased variability in lane position (and headway); and (iii) longer decision times. Whereas these results indicate a 'change' from normal conditions, they do not necessarily reflect 'impairment' in terms of performance effectiveness since few studies report increased accident risk. However, the results do suggest 'impairment' in terms of performance efficiency given that the increased compensatory effort resulting from cannabis use limits the available resources to cope with any additional, unexpected or high demand, events.
In conclusion, cannabis impairs driving behaviour. However, this impairment is mediated in that subjects under cannabis treatment appear to perceive that they are indeed impaired. Where they can compensate, they do, for example, by not overtaking, by slowing down and by focusing their attention when they know a response will be required. However, such compensation is not possible where events are unexpected or where continuous attention is required. Effects of driving behaviour are present up to an hour after smoking but do not continue for extended periods.
"With respect to comparisons between alcohol and marijuana effects, these substances tend to differ in their effects. In contrast to the compensatory behaviour exhibited by subjects under cannabis treatment, subjects who have received alcohol tend to drive in a more risky manner. Both substances impair performance, however, the more cautious behaviour of subjects who have received cannabis decreases the impact of the drug on performance, where the opposite holds true for alcohol." (Smiley, 1998, p. 19)
It is notable that the studies based on laboratory tests tend to indicate more effects of cannabis consumption than those using simulation and road observation methods. The higher incidence of effects under laboratory test conditions relative to the 'natural' conditions of simulation and road studies has been attributed to (i) reduced error variance from greater control of test conditions; (ii) higher task demand under novel test conditions; (iii) irrelevance or non-equivalence of laboratory test to component of driving; (iv) greater latitude for compensatory effort under 'natural' conditions; and (v) self-selection under 'natural' conditions not to be exposed to risk (e.g., not drive).
"It is exceedingly difficult to explain the disparity in results obtained by laboratory tests and in driving situations. Rather than try, it seems better for the moment to assume that both sets of results are valid for the particular circumstances under which they were obtained. It demonstrates, however, that performance decrements obtained under the artificial and non-life threatening conditions in the laboratory do not automatically predict similar decrements in driving situations that are closer to real-world driving." (emphasis added, Robbe, 1994, p. 66).
The greater propensity for cannabis effects under laboratory test conditions is somewhat paradoxical given that the laboratory tests have typically used smaller doses of cannabis than the simulation and road studies. It is also controversial since the limited number of studies and absence of demonstrable effects under natural driving conditions has impeded the development of transport policy regarding cannabis use. Whereas evidence of drug impairment under laboratory test conditions is not sufficient to provide an increase in accident risk, it does demonstrate cause for concern. This concern should then guide subsequent research under simulation and road conditions to investigate more valid evidence of impairment. Such efforts should be guided by relevant laboratory tests that relate to a model of driving, and use of a standard test methodology and reporting format for both simulation and road based research. This will provide a logical sequence of inquiry that can include both the replication of key findings, and the comparison of effects between a range of study designs.
Attempts to estimate the accident risk associated with cannabis use have relied on epidemiological evidence from accident involved drivers. Whereas this evidence has identified the presence of cannabis amongst accident involved drivers, accident risk can not be calculated given the absence of valid baseline data for cannabis detected in the non-involved population. Moreover, the presence of cannabis is often confounded by alcohol, as well as demographic and psychosocial risk factors associated with both drug and alcohol use. Current methodologies can only determine the presence of cannabinoids, but not evidence of impairment.
Thus, not only is it problematic to estimate the percentage of accident involvements associated with cannabis use alone, there is no evidence that impairment resulting from cannabis use causes accidents. Attempts to alleviate these problems by calculating risk of culpability for an accident (rather than the risk of having an accident) suggest that cannabis may actually reduce responsibility for accidents. It is evident that further epidemiological research is necessary. Such research must adopt a 'Grand Rapids' methodology of obtaining valid baseline data matched to positive cases, as well as including sufficient sample sizes and a valid operational definition of 'responsibility'. Such research may benefit from differentiating between accident types and accounting for relevant covariates including driver age and sex.
Much of the interest in cannabis as a potential accident risk factor is related to the concern about alcohol. Both alcohol and cannabis have an intoxicating effect that alters the psychological state of the individual. However, the mechanism of action and form of intoxication of these drugs are distinct. Alcohol may provide a useful metric to evaluate the effect of cannabis. Moreover, given the existence of a set legal limit for alcohol, research of the dose equivalence between alcohol and cannabis for performance relevant to accident risk may provide a method of determining a safety critical limit for cannabis. German research based on meta-analyses has concluded that 50% of performance is impaired at 11ng/ml THC, making this an equivalent level of intoxication to 0.08% BAC, although more recent and driving specific studies need to be compared with respect to effect size to confirm these suggested dose equivalences.
However, it is important not to use parallel reasoning between alcohol and cannabis to dictate the research agenda and transport policy for cannabis alone. Such reasoning is particularly inappropriate for medicinal applications of cannabis derivatives.
"There has developed an understandable but regrettable tendency to separate alcohol from other impairing agents and at the same time to enact tough drugs-driving legislation which remains firmly based on experience with alcohol. This is illogical, inappropriate and usually quite unenforceable. There is often pressure to define, for legal purposes, critical body fluid concentrations above which all would be impaired and below which no impairment would be demonstrable. At present, this is not possible. In addition to the considerably more complex pharmacokinetic and pharmacodynamic effects of most drugs compared with those of ethanol, there is also the proposition that therapeutic drugs, used for legitimate purposes, may improve the driving ability of certain patients despite their ability to impair performance normal individuals." (Starmer et al., 1988, p. 35-36)
One approach to deriving a legal limit for cannabis during driving has been to set the threshold to the level at which 50% of results show impairment. For alcohol, Berghaus showed a BAC of 0.073% corresponded to impairment on 50% of 923 performance measures examined. The corresponding threshold for THC was 11ng/ml. This is the closest estimate of dose equivalence to date, although there are recent, well-controlled studies which have not been included in such meta-analyses. A necessary research undertaking would be a thorough meta-analysis of results to date, using statistical measures of effect size related to dose.
An alternative is to specify a zero limit threshold, where any level of detected drug is prohibited. However, such an approach is premised on the philosophy that any drug which alters the state of the driver is inconsistent with the responsibility of the driver to operate the vehicle only when in an optimal state. This approach is associated with its own impracticalities of defining an 'optimal' state and deciding if reasons for impairment (i.e. deviation from the optimal state) other than drug use can be prosecuted (e.g., fatigue, poor driving skills, age related decline in capacity to drive etc.).
Ultimately, the direction of transport policy will be decided by an assignment of relative priorities. On one hand, any drug that affects the alertness and capability of a driver to safely operate a vehicle must be precluded. On the other hand, there are other factors such as alcohol which have a stronger association with accidents.
"Of the many psychotropic drugs, licit and illicit, that are available and used by people who subsequently drive, cannabis may well be amongst the least harmful. Campaigns to discourage the use of cannabis by drivers are certainly warranted. But concentrating a campaign on cannabis alone may not be in proportion to the safety problem it causes" (Robbe, 1994, p. 177).
The main conclusion from this report is that there is insufficient evidence of the accident risk associated with cannabis. Future research directed to the formulation of transport policy is required to resolve many key issues that remain unresolved in relation to cannabis and driving. However, it must be recognised that these issues may not be readily resolved given the ethical, legal, and technical impediments of the research domain (Hall et al., 1994).
This call for additional research was set forth by Robbe at the conclusion of his oft cited treatise on cannabis and driving:
"This dissertation should not be considered as the final word. It should, however, remain for a while as a point of departure for subsequent studies that will ultimately complete the picture of cannabis effects on driving performance" (p. 177).
It is now imperative that funding is made available to facilitate further research. However, such research must also be supported by mechanisms to accommodate legal and ethical requirements in this area. "In the meantime, cannabis users should be urged not to drive while intoxicated by cannabis, and they should be particularly warned of the dangers of driving after combining both alcohol and cannabis" (Hall et al., 1994, p. 50)."
how the the bloody hell did thispost end up in the middel of the tread.
weird man I think the bulitin board soft wares had a few spliffs. :-)
>> Edited by outlaw on Wednesday 29th May 20:55
LETS SEE IF THIS WILL POST TO THE RIGHT PLACE
NOPE IT GONE IN THE WROUGN PLACE AGAIN nO ,i AINT DOING IT FOR A WIND UP.
Let just get It clear before I post, I got nothing against a spliff, but I hate the stuff my self and dont smoke it.
however I do belive all drugs should be legalised
inludind hard drugs for all adults.
It would save a foutuen each year pluss if they any one wants to spend there life in a druged up haze or kill there selfs. Thats there porblem, no one else. so I say let em get on with it.
But heres the Conclusion, you can find the whole lot here:
www.roads.dtlr.gov.uk/roadsafety/cannabis/
aparently the dint like the test results much
"
Department of the Environment,
Transport and the Regions
Cannabis and Driving:
A Review of the Literature and Commentary
--------------------------------------------------------------------------------
CHAPTER 11
Conclusion
This report has summarised available research on cannabis and driving. The report has included the main review documents for research published before 1994 (e.g., Hall et al., 1994; Robbe, 1994) as well as primary sources for research published from 1994 using keyword searches of relevant databases. This synthesis of research was directed to identify key research objectives to develop a rational transport policy for cannabis and driving.
It is apparent that cannabis is the most common 'illicit' drug. Indeed, there is some evidence to indicate an increasing trend in its availability and use in the general population. Thus, in terms of drug use and traffic safety, this would suggest that cannabis represents the major drug type to be addressed by transport safety policy.
However, there is not sufficient evidence indicating the percentage of drivers that operate a vehicle after consuming cannabis, particularly during the time period of any intoxicating effect. As a result, there is no precise estimate of the percentage of drivers exposed to cannabis as an accident risk factor. Indeed, it is problematic to estimate the extent of exposure independent of other risk factors associated with cannabis use such as alcohol. Moreover, the demographic group most frequently using cannabis already has the greatest a priori accident risk due to driving inexperience and factors associated with youth relating to risk taking, delinquency and motivation. These demographic and psychosocial variables may relate to both drug use and accident risk, thereby presenting an artificial relationship between use of drugs and accident involvement.
The recent developments and discoveries in pharmacology such as cannabinoid receptors and endogenous ligands are important and exciting. These and the increased understanding of the mechanism of action of cannabis will mean that new or improved methods of detection are likely. Most promising to date in terms of reliability, detection of recent consumption and practical application are methods for determining presence of metabolites in saliva and sweat. These developments and ongoing research also have implications for therapeutic drug development. New compounds based on cannabinoids will need careful evaluation to confirm their lack of psychoactive and psychomotor effects.
Evidence of impairment from the consumption of cannabis has been reported by studies using laboratory tests, driving simulators and on-road observation. The laboratory tests generally indicate acute impairment of memory, attention and psychomotor control. Both simulation and road trials generally find that driving behaviour shortly after consumption of larger doses of cannabis results in (i) a more cautious driving style; (ii) increased variability in lane position (and headway); and (iii) longer decision times. Whereas these results indicate a 'change' from normal conditions, they do not necessarily reflect 'impairment' in terms of performance effectiveness since few studies report increased accident risk. However, the results do suggest 'impairment' in terms of performance efficiency given that the increased compensatory effort resulting from cannabis use limits the available resources to cope with any additional, unexpected or high demand, events.
In conclusion, cannabis impairs driving behaviour. However, this impairment is mediated in that subjects under cannabis treatment appear to perceive that they are indeed impaired. Where they can compensate, they do, for example, by not overtaking, by slowing down and by focusing their attention when they know a response will be required. However, such compensation is not possible where events are unexpected or where continuous attention is required. Effects of driving behaviour are present up to an hour after smoking but do not continue for extended periods.
"With respect to comparisons between alcohol and marijuana effects, these substances tend to differ in their effects. In contrast to the compensatory behaviour exhibited by subjects under cannabis treatment, subjects who have received alcohol tend to drive in a more risky manner. Both substances impair performance, however, the more cautious behaviour of subjects who have received cannabis decreases the impact of the drug on performance, where the opposite holds true for alcohol." (Smiley, 1998, p. 19)
It is notable that the studies based on laboratory tests tend to indicate more effects of cannabis consumption than those using simulation and road observation methods. The higher incidence of effects under laboratory test conditions relative to the 'natural' conditions of simulation and road studies has been attributed to (i) reduced error variance from greater control of test conditions; (ii) higher task demand under novel test conditions; (iii) irrelevance or non-equivalence of laboratory test to component of driving; (iv) greater latitude for compensatory effort under 'natural' conditions; and (v) self-selection under 'natural' conditions not to be exposed to risk (e.g., not drive).
"It is exceedingly difficult to explain the disparity in results obtained by laboratory tests and in driving situations. Rather than try, it seems better for the moment to assume that both sets of results are valid for the particular circumstances under which they were obtained. It demonstrates, however, that performance decrements obtained under the artificial and non-life threatening conditions in the laboratory do not automatically predict similar decrements in driving situations that are closer to real-world driving." (emphasis added, Robbe, 1994, p. 66).
The greater propensity for cannabis effects under laboratory test conditions is somewhat paradoxical given that the laboratory tests have typically used smaller doses of cannabis than the simulation and road studies. It is also controversial since the limited number of studies and absence of demonstrable effects under natural driving conditions has impeded the development of transport policy regarding cannabis use. Whereas evidence of drug impairment under laboratory test conditions is not sufficient to provide an increase in accident risk, it does demonstrate cause for concern. This concern should then guide subsequent research under simulation and road conditions to investigate more valid evidence of impairment. Such efforts should be guided by relevant laboratory tests that relate to a model of driving, and use of a standard test methodology and reporting format for both simulation and road based research. This will provide a logical sequence of inquiry that can include both the replication of key findings, and the comparison of effects between a range of study designs.
Attempts to estimate the accident risk associated with cannabis use have relied on epidemiological evidence from accident involved drivers. Whereas this evidence has identified the presence of cannabis amongst accident involved drivers, accident risk can not be calculated given the absence of valid baseline data for cannabis detected in the non-involved population. Moreover, the presence of cannabis is often confounded by alcohol, as well as demographic and psychosocial risk factors associated with both drug and alcohol use. Current methodologies can only determine the presence of cannabinoids, but not evidence of impairment.
Thus, not only is it problematic to estimate the percentage of accident involvements associated with cannabis use alone, there is no evidence that impairment resulting from cannabis use causes accidents. Attempts to alleviate these problems by calculating risk of culpability for an accident (rather than the risk of having an accident) suggest that cannabis may actually reduce responsibility for accidents. It is evident that further epidemiological research is necessary. Such research must adopt a 'Grand Rapids' methodology of obtaining valid baseline data matched to positive cases, as well as including sufficient sample sizes and a valid operational definition of 'responsibility'. Such research may benefit from differentiating between accident types and accounting for relevant covariates including driver age and sex.
Much of the interest in cannabis as a potential accident risk factor is related to the concern about alcohol. Both alcohol and cannabis have an intoxicating effect that alters the psychological state of the individual. However, the mechanism of action and form of intoxication of these drugs are distinct. Alcohol may provide a useful metric to evaluate the effect of cannabis. Moreover, given the existence of a set legal limit for alcohol, research of the dose equivalence between alcohol and cannabis for performance relevant to accident risk may provide a method of determining a safety critical limit for cannabis. German research based on meta-analyses has concluded that 50% of performance is impaired at 11ng/ml THC, making this an equivalent level of intoxication to 0.08% BAC, although more recent and driving specific studies need to be compared with respect to effect size to confirm these suggested dose equivalences.
However, it is important not to use parallel reasoning between alcohol and cannabis to dictate the research agenda and transport policy for cannabis alone. Such reasoning is particularly inappropriate for medicinal applications of cannabis derivatives.
"There has developed an understandable but regrettable tendency to separate alcohol from other impairing agents and at the same time to enact tough drugs-driving legislation which remains firmly based on experience with alcohol. This is illogical, inappropriate and usually quite unenforceable. There is often pressure to define, for legal purposes, critical body fluid concentrations above which all would be impaired and below which no impairment would be demonstrable. At present, this is not possible. In addition to the considerably more complex pharmacokinetic and pharmacodynamic effects of most drugs compared with those of ethanol, there is also the proposition that therapeutic drugs, used for legitimate purposes, may improve the driving ability of certain patients despite their ability to impair performance normal individuals." (Starmer et al., 1988, p. 35-36)
One approach to deriving a legal limit for cannabis during driving has been to set the threshold to the level at which 50% of results show impairment. For alcohol, Berghaus showed a BAC of 0.073% corresponded to impairment on 50% of 923 performance measures examined. The corresponding threshold for THC was 11ng/ml. This is the closest estimate of dose equivalence to date, although there are recent, well-controlled studies which have not been included in such meta-analyses. A necessary research undertaking would be a thorough meta-analysis of results to date, using statistical measures of effect size related to dose.
An alternative is to specify a zero limit threshold, where any level of detected drug is prohibited. However, such an approach is premised on the philosophy that any drug which alters the state of the driver is inconsistent with the responsibility of the driver to operate the vehicle only when in an optimal state. This approach is associated with its own impracticalities of defining an 'optimal' state and deciding if reasons for impairment (i.e. deviation from the optimal state) other than drug use can be prosecuted (e.g., fatigue, poor driving skills, age related decline in capacity to drive etc.).
Ultimately, the direction of transport policy will be decided by an assignment of relative priorities. On one hand, any drug that affects the alertness and capability of a driver to safely operate a vehicle must be precluded. On the other hand, there are other factors such as alcohol which have a stronger association with accidents.
"Of the many psychotropic drugs, licit and illicit, that are available and used by people who subsequently drive, cannabis may well be amongst the least harmful. Campaigns to discourage the use of cannabis by drivers are certainly warranted. But concentrating a campaign on cannabis alone may not be in proportion to the safety problem it causes" (Robbe, 1994, p. 177).
The main conclusion from this report is that there is insufficient evidence of the accident risk associated with cannabis. Future research directed to the formulation of transport policy is required to resolve many key issues that remain unresolved in relation to cannabis and driving. However, it must be recognised that these issues may not be readily resolved given the ethical, legal, and technical impediments of the research domain (Hall et al., 1994).
This call for additional research was set forth by Robbe at the conclusion of his oft cited treatise on cannabis and driving:
"This dissertation should not be considered as the final word. It should, however, remain for a while as a point of departure for subsequent studies that will ultimately complete the picture of cannabis effects on driving performance" (p. 177).
It is now imperative that funding is made available to facilitate further research. However, such research must also be supported by mechanisms to accommodate legal and ethical requirements in this area. "In the meantime, cannabis users should be urged not to drive while intoxicated by cannabis, and they should be particularly warned of the dangers of driving after combining both alcohol and cannabis" (Hall et al., 1994, p. 50)."
how the the bloody hell did thispost end up in the middel of the tread.
weird man I think the bulitin board soft wares had a few spliffs. :-)
>> Edited by outlaw on Wednesday 29th May 20:59
quote:yeah - some days I can't help but imbibe the Devil's Advocaat
good oh - somehing I can actually disagree with you on!
quote:Can't argue with you there mate..
I aint saying being stoned makes you a bad driver...or that being p*ssed, on a mobile, smoking a fag, changing a tape, talking to your passenger, doing handbrake turns, topping 140 or anything else does either. but seeing as I think about 70% of the general public should ALREADY be off the roads, god help us when they're out of it as well!!
As ever the core of the problems is the overall poor standard of humanity
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