6 ms·

Marijuana Users Are Safer Drivers Than Non-Marijuana Users, New Study Shows

26 points by zoowar 15y ago

Alex3917 15y ago
I don't see any evidence that they actually did a study. The link to the study just takes you to a top ten list.
th0ma5 15y ago
The study has a statement that smokers have a lower responsibility rate in accidents, but I'd be very curious about response time to unexpected events that can occur while driving. Granted, if you're going slower, you would have more time to respond.
- Alex3917 15y ago
  "I'd be very curious about response time to unexpected events that can occur while driving." That depends on the dosage, the person's tolerance, the route of administration, how long it's been since the person used the substance, etc. There isn't going to be a single number. That said, someone driving at the legal limit for alcohol has on average a 3x risk of causing a fatal accident. Whereas someone under the influence of marijuana generally has a risk of less than 2x, meaning that it really shouldn't be illegal.
benologist 15y ago
This is the press release equivalent of infographic spam - obscure site manufactures some substance-less eye candy, or in this case pander candy, to generate backlinks.
- billpatrianakos 15y ago
  Yes! It's so easy to get suckered into a discussion about the validity of the study or on marijuana use in general but what you said was my first reaction to the post. For such a bunch of smart people I wonder why we get suckered in like this.
deleted 15y ago
[deleted]
tokenadult 15y ago
The underlying study http://www.4autoinsurancequote.org/uncategorized/reasons-why-marijuana-users-are-safe-drivers/ http://www.4autoinsurancequote.org/uncategorized/reasons-why... does not say what the headline here (which is, correctly, the original article headine) says. The claim in the lead paragraphs of the study is actually much more nuanced: "There have been several studies done over the past 20 years and every one of them has revealed that using marijuana actually has a very minor, if any, effect on the ability of a person to drive a car or other vehicle." Anyway, that conclusion still suggests taking a close look at the study methodologies http://norvig.com/experiment-design.html http://norvig.com/experiment-design.html to see if the studies were really well designed to describe general reality or not. Much more study needs to be done before concluding that, for example, increased marijuana use would invariably lead to increased road safety, which someone might mistakenly conclude from the headline statement of the article kindly submitted here.
- Alex3917 15y ago
  The link you are pointing to is a blog post, not a study. Also, if you read the underlying studies you'll see that the ones where they give drivers marijuana under controlled conditions usually don't result in any increased risk at all, whereas with alcohol it's very easy to see a huge increase in risk using the exact same methodology). The second kind of studies they generally use are observational studies, which tend to peg the underlying risk increase from marijuana at around 2x (as compared with alcohol, which gives on average a 3x increase at the legal limit). However, the authors of these observational studies themselves say that this is most likely actually an overestimate of the risk, not an underestimate. Here are the caveats from one recent metastudy: "Although this meta-analysis provides compelling evidence for an association between marijuana use and crash risk, it is impossible to infer causality from these epidemiologic data alone. A more rigorous assessment of the nature of the relation between marijuana use and crash risk is complicated by several factors. Among them are bias from measured and unmeasured confounding and the difficulty posed by polydrug use. Although most of the studies included in this meta-analysis considered some confounding variables in evaluating the association between marijuana use and crash risk, adjustment was usually limited to a few measured covariates, such as age, sex, and alcohol use. Additional variables that may confound the relation between marijuana use and crash risk, such as exposure to driving and risk-taking propensity, are often difficult to mea- sure and thus are not readily available. Other factors confounding the relation between marijuana use and crash risk are divergent definitions and assessments of marijuana use across studies. Different methods of assessing marijuana use (e.g., self- report, urine tests, and blood tests) may have different levels of validity and reliability (39). Most of these screenings determine whether marijuana was used within the past few weeks, whereas acute impairment in driving skills from marijuana use lasts only 3–4 hours (39). Furthermore, because marijuana is an illicit drug in most countries, it is possible that drivers in the comparison groups might be less likely than those involved in crashes to submit to testing, which could lead to overestimation of the effect of marijuana use on crash risk (43). Polydrug use represents another challenge to determining the role of marijuana in motor vehicle crashes. Polydrug use by drivers is common, with up to a quarter of drivers injured in crashes testing positive for 2 or more drugs (including alcohol) (42, 73, 74). Although it is necessary to understand the effect of individual drugs on driving performance, the high prevalence of polydrug use by drivers makes it difficult to do so. On the other hand, assessing interaction effects on driving safety of different drug combinations based on epidemiologic data would require very large study samples, comprehensive drug testing data, and tremendous financial and other resources (42–44, 75, 76). One of the studies included in the meta-analysis evaluated the effect of marijuana in combination with alcohol on crash risk and found that the combination of marijuana and alcohol confers an exceptionally heightened risk to driving safety (68). Experimental studies show that cannabis and alcohol affect different cognitive functions that may interact with driving performance (41). Specifically, cannabis seems to impair automatic behaviors, such as tracking, at low doses and impair ability to perform more complex tasks at higher doses, whereas alcohol seems to more readily affect functions requiring cognitive control (41). While both marijuana and alcohol can impair driving performance, there appears to be greater variations in effects of marijuana compared with alcohol (41)." source: Marijuana Use and Motor Vehicle Crashes Mu-Chen Li, Joanne E. Brady, Charles J. DiMaggio, Arielle R. Lusardi, Keane Y. Tzong, and Guohua Li
dutchbrit 15y ago
As someone that occasionally smokes a joint, I really don't feel safe driving - but joints can have different effects on different people, the strength etc... Someone that smokes up daily is more resistant than people that smoke on small occasions
aaronbrethorst 15y ago
I've read conflicting reports before. Seattle's alternative weekly, The Stranger, has been talking a lot about pot and driving in light of the ballot referendum we'll have this year on pot legalization in Washington state. Here are a couple choice bits: The report finds that only one of the participants had active THC levels above 5 ng/mL on "admission (day 1)," which suggests that the woman was high when she arrived...The woman had reported smoking four blunts per day. and, Likewise, Grotenhermen et al found in 2005: "The crash risk apparently begins to exceed that of sober drivers as THC concentrations in whole blood reach 5–10 ng/mL." http://slog.thestranger.com/slog/archives/2012/02/24/sorry-medical-marijuana-activists-your-study-doesnt-prove-that-i-502-will-nab-sober-drivers-for-duis http://slog.thestranger.com/slog/archives/2012/02/24/sorry-m... So, in other words, yes smoking pot can impair your ability to operate heavy machinery, but you have to be smoking quite a bit (or not used to it, ostensibly).
keypusher 15y ago
This source is extremely questionable. This is basically a blog post (http://www.4autoinsurancequote.org/uncategorized/reasons-why-marijuana-users-are-safe-drivers/ http://www.4autoinsurancequote.org/uncategorized/reasons-why...) and a press release (http://www.prweb.com/releases/prweb2012/4/prweb9375729.htm http://www.prweb.com/releases/prweb2012/4/prweb9375729.htm) summarizing some reasons that marijuana users are less dangerous on the road than drunks. There is one study linked by the NHTSA which showed they drive slower than drunks, and the rest appears to be pure conjecture. All of this is this re-interpreted in the SFGate article to suggest marijuana users are safer than non-marijuana users. While I agree with the sentiment, this article is of questionable validity and does not really fall into the tech or programming news that belongs here.
- billpatrianakos 15y ago
  I agree with you in general. One point on this belonging here though: HN isn't only about tech and programming. The submission guidelines say that anything hackers would find interesting is okay. So this one is just a judgement call, it's not totally cut and dry. I can see how it can be debatable. That said, I think a lot of us are marijuana smokers (at least that's the vibe I get from others I've met here) and many of us are all about progressive ideas like legalizing marijuana and such. I'm don't exactly fall into that category this time but I can still see why it's of interest to many here.
ktizo 15y ago
There was a UK study from the Transport Research Laboratory in 2000 that said that people who were slightly stoned tended to keep their distance more and their speed down. People who were boxed were rubbish however. Sobriety is generally the best state for driving.
crusso 15y ago
Of course they're safer. They're sitting in their driveways, giggling their heads off because of the funny shapes of their keys until they remember that they're hungry and head back inside for those Doritos that fell behind the couch the other day.
billpatrianakos 15y ago
Seems like another case of using statistics to prove anything. It's not the study I don't believe but the interpretation. Before I go on, I'll give full disclosure: I'm on the board of a drug use prevention/treatment charity that works closely with government agencies and private companies that research all types of drug use and related subjects like that of this article. I'm also a former poly drug abuser (that means I was a gigantic stoner some years back too). I think the implications made here are dangerous. They encourage current pot smokers to keep driving stoned and sends the message that driving stoned is safer than driving sober. That's just not so. The reason for the statistic showing marijuana users being responsible for accidents less than sober drivers may simply be a product of the fact that there are just less stoned people driving than sober people. There's no doubt that marijuana impairs your ability to operate a vehicle. It slows reaction times and messes with one's perception of speed and distance. It also has an effect on focus. Some people become distracted while others focus too strongly on one particular thing. That effect seems dependent partly upon dosage used and the individual. Trying to be cautious and actually doing it successfully are very different. Slow driving does not amount to safe driving. Driving slowly can lead to accidents just the same as speeding. Driving requires you to be mindful of many things at once. Going back to what I said about focus, being high while driving can make the task overwhelming for those who experience a lack of focus while under the influence or it can a driver to be far top focused on one particular aspect of diving. For example, a diver can be so focused on his speed that he doesn't notice the guy tailing him too closely in the rear view. Driver has to stop short because he misjudged the distance and speed of the cars in front of him and wasn't focused enough on them causing the guy tailing him to crash. That's an avoidable situation and one where the stoned driver would not be at fault. Regardless of whether the driver who was tailing too closely shouldn't have done that the point is that this is an example of an avoidable situation that is actually very realistic. I'll concede that marijuana is far less dangerous than alcohol. In fact, despite my position on the board of the charity I mentioned and despite my less-than-good experience with drug use and subsequent rehab, I still take the position that pot is generally harmless. So what I'm saying isn't coming from some hard line "just say no/all drugs are evil" perspective but we can't just deny that marijuana use doesn't impair you in the ways I describe. I don't even believe its bad for you (except for inhaling the smoke - even if it a billion times less dangerous than cigarettes it's still never a good idea to inhale any kind of smoke). Unfortunately, articles like this will give some people the impression that marijuana is good for you, absolutely, and only good things can come of its use. That's irresponsible and one single study showing this will not convince me that driving while stoned is safer than driving sober. As far as I'm concerned this is just a really catchy article that should not be taken at face value. The study could have major flaws and for all we know it may just be a way to get publicity for the insurance company that sponsored it. The spin on this is really irresponsible. Even total stoners like the kind my friends and I once were should take it with a grain of salt but I doubt they will because it's just more reinforcement for their beliefs surrounding marijuana use. You know what I mean... There are always those groups of suburban, upper middle class white kids that are nerdy then discover weed, smoke some, turn into stoners, and then they all talk about how marijuana is the cure for everything from cancer to aids to the common cold and a way to avoid death itself. It's those kids I fear for when they read this.

26 points by zoowar 15y ago

I don't see any evidence that they actually did a study. The link to the study just takes you to a top ten list.

The study has a statement that smokers have a lower responsibility rate in accidents, but I'd be very curious about response time to unexpected events that can occur while driving. Granted, if you're going slower, you would have more time to respond.

Alex3917 15y ago
"I'd be very curious about response time to unexpected events that can occur while driving." That depends on the dosage, the person's tolerance, the route of administration, how long it's been since the person used the substance, etc. There isn't going to be a single number. That said, someone driving at the legal limit for alcohol has on average a 3x risk of causing a fatal accident. Whereas someone under the influence of marijuana generally has a risk of less than 2x, meaning that it really shouldn't be illegal.

benologist 15y ago

This is the press release equivalent of infographic spam - obscure site manufactures some substance-less eye candy, or in this case pander candy, to generate backlinks.

billpatrianakos 15y ago
Yes! It's so easy to get suckered into a discussion about the validity of the study or on marijuana use in general but what you said was my first reaction to the post. For such a bunch of smart people I wonder why we get suckered in like this.

deleted 15y ago

[deleted]

tokenadult 15y ago

The underlying study http://www.4autoinsurancequote.org/uncategorized/reasons-why-marijuana-users-are-safe-drivers/ http://www.4autoinsurancequote.org/uncategorized/reasons-why... does not say what the headline here (which is, correctly, the original article headine) says. The claim in the lead paragraphs of the study is actually much more nuanced: "There have been several studies done over the past 20 years and every one of them has revealed that using marijuana actually has a very minor, if any, effect on the ability of a person to drive a car or other vehicle." Anyway, that conclusion still suggests taking a close look at the study methodologies http://norvig.com/experiment-design.html http://norvig.com/experiment-design.html to see if the studies were really well designed to describe general reality or not. Much more study needs to be done before concluding that, for example, increased marijuana use would invariably lead to increased road safety, which someone might mistakenly conclude from the headline statement of the article kindly submitted here.

Alex3917 15y ago
The link you are pointing to is a blog post, not a study. Also, if you read the underlying studies you'll see that the ones where they give drivers marijuana under controlled conditions usually don't result in any increased risk at all, whereas with alcohol it's very easy to see a huge increase in risk using the exact same methodology). The second kind of studies they generally use are observational studies, which tend to peg the underlying risk increase from marijuana at around 2x (as compared with alcohol, which gives on average a 3x increase at the legal limit). However, the authors of these observational studies themselves say that this is most likely actually an overestimate of the risk, not an underestimate. Here are the caveats from one recent metastudy: "Although this meta-analysis provides compelling evidence for an association between marijuana use and crash risk, it is impossible to infer causality from these epidemiologic data alone. A more rigorous assessment of the nature of the relation between marijuana use and crash risk is complicated by several factors. Among them are bias from measured and unmeasured confounding and the difficulty posed by polydrug use. Although most of the studies included in this meta-analysis considered some confounding variables in evaluating the association between marijuana use and crash risk, adjustment was usually limited to a few measured covariates, such as age, sex, and alcohol use. Additional variables that may confound the relation between marijuana use and crash risk, such as exposure to driving and risk-taking propensity, are often difficult to mea- sure and thus are not readily available. Other factors confounding the relation between marijuana use and crash risk are divergent definitions and assessments of marijuana use across studies. Different methods of assessing marijuana use (e.g., self- report, urine tests, and blood tests) may have different levels of validity and reliability (39). Most of these screenings determine whether marijuana was used within the past few weeks, whereas acute impairment in driving skills from marijuana use lasts only 3–4 hours (39). Furthermore, because marijuana is an illicit drug in most countries, it is possible that drivers in the comparison groups might be less likely than those involved in crashes to submit to testing, which could lead to overestimation of the effect of marijuana use on crash risk (43). Polydrug use represents another challenge to determining the role of marijuana in motor vehicle crashes. Polydrug use by drivers is common, with up to a quarter of drivers injured in crashes testing positive for 2 or more drugs (including alcohol) (42, 73, 74). Although it is necessary to understand the effect of individual drugs on driving performance, the high prevalence of polydrug use by drivers makes it difficult to do so. On the other hand, assessing interaction effects on driving safety of different drug combinations based on epidemiologic data would require very large study samples, comprehensive drug testing data, and tremendous financial and other resources (42–44, 75, 76). One of the studies included in the meta-analysis evaluated the effect of marijuana in combination with alcohol on crash risk and found that the combination of marijuana and alcohol confers an exceptionally heightened risk to driving safety (68). Experimental studies show that cannabis and alcohol affect different cognitive functions that may interact with driving performance (41). Specifically, cannabis seems to impair automatic behaviors, such as tracking, at low doses and impair ability to perform more complex tasks at higher doses, whereas alcohol seems to more readily affect functions requiring cognitive control (41). While both marijuana and alcohol can impair driving performance, there appears to be greater variations in effects of marijuana compared with alcohol (41)." source: Marijuana Use and Motor Vehicle Crashes Mu-Chen Li, Joanne E. Brady, Charles J. DiMaggio, Arielle R. Lusardi, Keane Y. Tzong, and Guohua Li

dutchbrit 15y ago

As someone that occasionally smokes a joint, I really don't feel safe driving - but joints can have different effects on different people, the strength etc... Someone that smokes up daily is more resistant than people that smoke on small occasions

aaronbrethorst 15y ago

I've read conflicting reports before. Seattle's alternative weekly, The Stranger, has been talking a lot about pot and driving in light of the ballot referendum we'll have this year on pot legalization in Washington state. Here are a couple choice bits: The report finds that only one of the participants had active THC levels above 5 ng/mL on "admission (day 1)," which suggests that the woman was high when she arrived...The woman had reported smoking four blunts per day. and, Likewise, Grotenhermen et al found in 2005: "The crash risk apparently begins to exceed that of sober drivers as THC concentrations in whole blood reach 5–10 ng/mL." http://slog.thestranger.com/slog/archives/2012/02/24/sorry-medical-marijuana-activists-your-study-doesnt-prove-that-i-502-will-nab-sober-drivers-for-duis http://slog.thestranger.com/slog/archives/2012/02/24/sorry-m... So, in other words, yes smoking pot can impair your ability to operate heavy machinery, but you have to be smoking quite a bit (or not used to it, ostensibly).

keypusher 15y ago

This source is extremely questionable. This is basically a blog post (http://www.4autoinsurancequote.org/uncategorized/reasons-why-marijuana-users-are-safe-drivers/ http://www.4autoinsurancequote.org/uncategorized/reasons-why...) and a press release (http://www.prweb.com/releases/prweb2012/4/prweb9375729.htm http://www.prweb.com/releases/prweb2012/4/prweb9375729.htm) summarizing some reasons that marijuana users are less dangerous on the road than drunks. There is one study linked by the NHTSA which showed they drive slower than drunks, and the rest appears to be pure conjecture. All of this is this re-interpreted in the SFGate article to suggest marijuana users are safer than non-marijuana users. While I agree with the sentiment, this article is of questionable validity and does not really fall into the tech or programming news that belongs here.

billpatrianakos 15y ago
I agree with you in general. One point on this belonging here though: HN isn't only about tech and programming. The submission guidelines say that anything hackers would find interesting is okay. So this one is just a judgement call, it's not totally cut and dry. I can see how it can be debatable. That said, I think a lot of us are marijuana smokers (at least that's the vibe I get from others I've met here) and many of us are all about progressive ideas like legalizing marijuana and such. I'm don't exactly fall into that category this time but I can still see why it's of interest to many here.

ktizo 15y ago

There was a UK study from the Transport Research Laboratory in 2000 that said that people who were slightly stoned tended to keep their distance more and their speed down. People who were boxed were rubbish however. Sobriety is generally the best state for driving.

crusso 15y ago

Of course they're safer. They're sitting in their driveways, giggling their heads off because of the funny shapes of their keys until they remember that they're hungry and head back inside for those Doritos that fell behind the couch the other day.

billpatrianakos 15y ago

Seems like another case of using statistics to prove anything. It's not the study I don't believe but the interpretation. Before I go on, I'll give full disclosure: I'm on the board of a drug use prevention/treatment charity that works closely with government agencies and private companies that research all types of drug use and related subjects like that of this article. I'm also a former poly drug abuser (that means I was a gigantic stoner some years back too). I think the implications made here are dangerous. They encourage current pot smokers to keep driving stoned and sends the message that driving stoned is safer than driving sober. That's just not so. The reason for the statistic showing marijuana users being responsible for accidents less than sober drivers may simply be a product of the fact that there are just less stoned people driving than sober people. There's no doubt that marijuana impairs your ability to operate a vehicle. It slows reaction times and messes with one's perception of speed and distance. It also has an effect on focus. Some people become distracted while others focus too strongly on one particular thing. That effect seems dependent partly upon dosage used and the individual. Trying to be cautious and actually doing it successfully are very different. Slow driving does not amount to safe driving. Driving slowly can lead to accidents just the same as speeding. Driving requires you to be mindful of many things at once. Going back to what I said about focus, being high while driving can make the task overwhelming for those who experience a lack of focus while under the influence or it can a driver to be far top focused on one particular aspect of diving. For example, a diver can be so focused on his speed that he doesn't notice the guy tailing him too closely in the rear view. Driver has to stop short because he misjudged the distance and speed of the cars in front of him and wasn't focused enough on them causing the guy tailing him to crash. That's an avoidable situation and one where the stoned driver would not be at fault. Regardless of whether the driver who was tailing too closely shouldn't have done that the point is that this is an example of an avoidable situation that is actually very realistic. I'll concede that marijuana is far less dangerous than alcohol. In fact, despite my position on the board of the charity I mentioned and despite my less-than-good experience with drug use and subsequent rehab, I still take the position that pot is generally harmless. So what I'm saying isn't coming from some hard line "just say no/all drugs are evil" perspective but we can't just deny that marijuana use doesn't impair you in the ways I describe. I don't even believe its bad for you (except for inhaling the smoke - even if it a billion times less dangerous than cigarettes it's still never a good idea to inhale any kind of smoke). Unfortunately, articles like this will give some people the impression that marijuana is good for you, absolutely, and only good things can come of its use. That's irresponsible and one single study showing this will not convince me that driving while stoned is safer than driving sober. As far as I'm concerned this is just a really catchy article that should not be taken at face value. The study could have major flaws and for all we know it may just be a way to get publicity for the insurance company that sponsored it. The spin on this is really irresponsible. Even total stoners like the kind my friends and I once were should take it with a grain of salt but I doubt they will because it's just more reinforcement for their beliefs surrounding marijuana use. You know what I mean... There are always those groups of suburban, upper middle class white kids that are nerdy then discover weed, smoke some, turn into stoners, and then they all talk about how marijuana is the cure for everything from cancer to aids to the common cold and a way to avoid death itself. It's those kids I fear for when they read this.