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With Pot Legal, Scientists Study Detection of Impaired Drivers
Hugh Pickens writes "A recent assessment by the National Highway Traffic Safety Administration, based on random roadside checks, found that 16.3% of all drivers nationwide at night were on various legal and illegal impairing drugs, half them high on marijuana. Now AP reports that with marijuana soon legal under state laws in Washington and Colorado, setting a standard comparable to blood-alcohol limits has sparked intense disagreement. Unlike portable breath tests for alcohol, there's no easily available way to determine whether someone is impaired from recent pot use. If scientists can't tell someone how much marijuana it will take for him or her to test over the threshold, how is the average pot user supposed to know? 'We've had decades of studies and experience with alcohol,' says Washington State Patrol spokesman Dan Coon. 'Marijuana is new, so it's going to take some time to figure out how the courts and prosecutors are going to handle it.' Driving within three hours of smoking pot is associated with a near doubling of the risk of fatal crashes. However, THC can remain in blood and saliva for highly variable times after the last use of the drug. Although the marijuana 'high' only lasts three to five hours, studies of heavy users in a locked hospital ward showed THC can be detected in the blood up to a week after they are abstinent, and the outer limit of detection time in saliva tests is not known. 'A lot of effort has gone into the study of drugged driving and marijuana, because that is the most prevalent drug, but we are not nearly to the point where we are with alcohol,' says Jeffrey P. Michael, the National Highway Traffic Safety Administration's impaired-driving director. 'We don't know what level of marijuana impairs a driver.'"
Just ask the driver what snack they'd like from the police car.
I know this is going to be a really odd way to detect impared drivers as far as people think but it is quite imperical and correct. You simply have the person do a coordination test with a video game type device. Impared drivers will show up whatever the reason. This can also be determined by blink rate and by detection of eye movements. It can be done very rapidly and has been in use by some municipal bus systems for some time with quite spectacular reductions in accidents. In fact this could be built into cars and we could have the car simply park if the driver is impared. (WOW! No arrest needed!) How about this wild idea. Skipping the police and stopping filling our jails and stopping all the fines etc while achieving the goal of public safety. It detects all types of imparement and doesn't bother wasting time on any other issue. Sleepy is detected too.
This is going to get to be a moot point shortly as the cars will have things like advanced adaptive cruise control that essentially drives the car. How about Google's self driving car etc. I think we are going to ban driving of cars by humans very shortly as they simply are the most dangerous part of the car driving system. You know the NUT behind the wheel is the most dangerous part of the car.
According to NORML, what basically happens when someone is driving while on marijuana is that while they're somewhat impaired, they also drive more cautiously and leave more space around them. The net effect is that while they're annoying, they aren't all that dangerous.
By contrast, when someone is driving drunk, they tend to be both impaired and reckless. The net effect is that thousands of people each year are killed by drunk drivers.
I am officially gone from
Bear in mind also that the normal risk of fatal crashes is low, so doubling it is doubling a number very near zero as it is.
Contrast that with alcohol (quote from a 1991 NIH article):
"Based on driver fatalities in single-vehicle crashes, it was estimated that each 0.02 percentage increase in the BAC of a driver with non-zero BAC nearly doubles the risk of being in a fatal crash."
That is probably not quite a beer's worth of alcohol for most body weights. So to put it another way, somebody who smokes pot while driving -- not "before", but during (a thing that in my youth I did with remarkable frequency) -- is roughly as impaired as if they had had just consumed a single beer. At those levels one does have to wonder about the error bars in the study -- statistically resolving one near-zero from another near-zero is actually remarkably difficult and requires ever so many samples and a totally unbiased sampling scheme with a complete lack of confounding variables -- so your assertion that the actual risk might even go down in those that aren't smoking pot and drinking a beer (where the latter is also difficult to detect and also doubles your risk all by itself) is not without possible merit.
Again from the article here: http://www.ncbi.nlm.nih.gov/pubmed/1875701:
"At BACs in the 0.05-0.09 percent range, the likelihood of a crash was at least nine times greater than at zero BAC for all age groups. Younger drivers with BACs in the 0.05-0.09 range had higher relative risks than older drivers, and females had higher relative risks than males. At very high BACs (at or above 0.15 percent), the risk of crashing was 300 to 600 times the risk at zero or near-zero BACs."
Note that at BAC's that are still in the legal range in most states, single car fatalities are nearly an order of magnitude greater than the single "doubling" of risk for immediate use of marijuana. That strongly suggests that the best thing to do about "impairment" from marijuana is -- ignore it, or as suggested above, use a field sobriety test, not a blood or saliva test. It is more or less irrelevant to driving skill. I would say (again, based on extensive experience) that this is not entirely true -- one can eat or smoke enough, potent enough, marijuana that driving is ill-advised, but in those cases field sobriety tests would be nearly impossible to pass as well. But it is actually somewhat difficult to get that stoned, and most pot smokers that I knew didn't want to drive when they were -- too scary.
But the simplest proofs are this. Whether or not it is legal, smoking pot and driving has been nearly universal forever among those that smoke pot. Most states are utterly unable to test for it, yet estimates of prevalence of usage (almost certainly low) suggest that anywhere up to 1/3 or 1/2 of people in certain age ranges at least occasionally smoke. Yet there is no positive association with this same group being a high risk on the road, outside of its tendency to drink. Alcohol is indeed a dangerous substance when it comes to driving, for obvious reasons, even for relatively small amounts. Pot is not, not until consumption is at extreme levels.
The last thing that confounds this is age. The distribution of fatal and non-fatal accidents with age is quite scary. A stoned 40 year old -- I mean a seriously wasted 40 year old stoner -- with a risk of accident 3 times his age-linked norm -- is a safer driver than a stone cold sober 19 year old. "Silverbacks" -- drivers on the high side of 75, where one's eyesight, hearing, and brain are all breaking down -- are safer still. Why? Because they drive (sober or not) carefully, and in particular far more conservatively than younger risk taking overconfident drivers. I'm living through my own sons' driving experience -- one at age 17 has his first car, now multiply scarred from driving it a whole month. One now 22, who at 18 took his eyes off of the road
Even when the experts all agree, they may well be mistaken. --- Bertrand Russell.
marijuana use in the absence of other substances impairs driving very little
Yeah, my stoner roommate used to say shit like that too. Of course, he also claimed it helped him study, but unless one considers watching the Cartoon Network all day "studying" then I never saw any evidence of it. And, while I never was a full-time stoner myself, I did smoke enough to know that I sure as shit wouldn't have felt comfortable driving on it (or doing anything else that required concentration).
Of course, I'm sure the stoner brigade can produce a plethora of studies claiming that weed is a fucking miracle cure-all with no downsides whatsoever, written by the same kind of biased researchers that produce studies showing that burning shit-tons of coal is great for the environment.
So your "gut feeling" is more relevant than peer-reviewed studies because you "feel" that the researchers are biased? Please refute the data with data, not emotional reactions to the "stoner brigade". For example, here is a study on driving under the influence of Cannabis that cites several other studies, if you have a problem with the data please point out the problem instead of resorting to logical fallacies.
http://epirev.oxfordjournals.org/content/21/2/222.full.pdf
Enigma
Impaired drivers are easy enough to spot.
A drunk driver will run a stop sign
The stoned driver waits for it to turn green.