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Federal Study: Marijuana Use Doesn't Increase Auto Crash Rates
An anonymous reader writes: After the legalization of marijuana in multiple states around the U.S., many are worried about a corresponding uptick in car crashes as people drive while under the influence of pot. But according to a new federal study (PDF) commissioned by the National Highway Traffic Safety Administration, those fears seem unfounded. They report that after adjusting for other factors (people who tend to drive after using marijuana also tend to be more crash-prone in general), there was no statistically significant increase in crash rates by drivers who tested positive for the drug. It's still a bad idea to drive high, but driving drunk is far, far worse: "One substance was shown to have a major influence on crashes: alcohol. The study confirmed the enormous danger of drinking and driving, even after age and sex adjustment: drivers with a 0.05% blood-alcohol level were found to be twice as likely to be in a crash. For a person weighing 180 to 190 pounds, that could be a single can of beer, glass of wine, or shot of liquor. At 0.08% (two drinks), the likelihood is quadrupled, and at .20% (four drinks or more), the risk is higher by 23 times."
The study is relatively meaningless because it wasn't collecting data about people who were HIGH on marijuana, but people who tested positive for having consumed it at some point. It could have been many hours ago or even days ago.
The conclusion reached by the horrible article is outright wrong and doesn't even have face validity. In fact, it is actually irresponsible and could cause society great harm by spreading possibly wrong information about the dangers of driving while altered.
Old stoner here. Been there done that. Yes driving while intoxicated on ANYTHING that alters the mind is BAD. If i had to pick the future a son-in-law that drinks or one that smokes, I'd take the drinker anytime; he's more likely to have a JOB! Trying to defend somthing as stupid as Intoxicated Driving just shows ones obsession with trying make Pot look good. We all know that pot has good uses; but driving is not one of them.
So do stone-cold sober drivers. So do old people. So do young people. So do drivers who are high, but who also had a few beers. The reason god invented statistical analysis was so that we could stop using anecdotal reports of "knowledge" as if they were fact.
That said, pot is like alcohol in one important respect, and that is that one can have a lot or a little THC on board, and then, there are different cannibinoids with different action on the brain, and since the THC tests are comparatively insensitive to both concentration and type compared to blood alcohol tests it isn't so easy to build a table that extracts the risk associated with driving while doing
bong hits of resin-saturated buds every few miles compared to driving having smoked part of a joint of everyday weed two hours earlier. You remain THC positive for days after smoking, but are at (possibly) increased risk for at most hours, where with alcohol one metabolizes roughly 1 drink/hour (perhaps a bit less if you get a lot of alcohol on board instead of a little) and can remain at increased risk for six or more hours if you drink heavily at a party.
However, TFA (which I actually read, as the subject interests me) basically showed that across all categories of pot use, there is a very small, statistically insignificant increase in risk of accident. They noted a number of studies that show decreased risk for moderate pot intake -- the theory here being that stoned people know that they are stoned and drive extra-carefully and end up safer than your average cell-phone-toting, conversation distracted, overworked and stressed out driver. This may well be cancelling out part of the increased risk associated with drivers doing hits while they drive. But designing a study to reveal this sort of thing would be challenging and in some sense isn't useful. Common sense suggests that it is dumb to do bong hits while driving at high speed down an interstate, especially while washing it down with a cold beer on the side, just as common sense suggests that it is dumb to drive without a seat belt or while texting or while fumbling with a music player or when one is really sleepy. Some (many) people, myself included, have done one or more of these things at one point or another in their lives.
The evidence, however, supports at most the citation of individuals caught driving WHILE smoking weed, not people who have THC in their bloodstream. That's the whole point of the study. Unless/until we have better tests that can easily detect the quantity and type of THC in your brain and studies based on those tests that are sensitive to and demonstrate the increased risk you assert is there based on anecdotal evidence (and sure, common sense) for some specific levels of concentration, the risk based on the mere presence of THC in the blood is substantially less than the risk associated with drinking a single beer. Field sobriety tests measuring actual intoxication are going to be more valuable than "just" the presence of THC.
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Even when the experts all agree, they may well be mistaken. --- Bertrand Russell.
Your first paragraph actually agrees with the point I was making; I think you simply misread what I wrote.
My point was that, if you are correct and they did not account for level of THC intoxication, that would mean that many of the THC-positive subjects likely were not intoxicated at all; e.g. completely sober. Those not-intoxicated but THC-positive subjects should have been recorded under the "Sober" column, which, in turn, would have painted a completely different picture, with many more "Sober" accidents and many fewer "THC-Involved" accidents.
In other words, I am agreeing with your assessment that level of intoxication is just as important for THC as it is for alcohol.
My take-away, here, is that the NHTSA did all they could to skew the testing in favor of painting pot in a negative light, while maintaining an appearance of neutrality, and the best they could do was to equate it with sobriety, within a reasonable margin of error.
APK quotes people (including myself) without context and should not be trusted. Just thought you should know.
(or related agency) published a detailed study on this subject in the late 90s.
as far as i remember i found this report on The Well, but i have since lost track of the file, and if anyone knows about it, i would really appreciate a chace to study it again.
the report was notable, as i remember, because it actually went so far as to suggest that weed makes better drivers - basically because they are more relaxed and therefore more likely to make the correct decisions in an emergency.