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An issue with having the legal limit at ~2-5ng/ml is that it makes habitual users be over the limit if they have smoked recently or not.[0] Making the prohibiti

by tokai 10mo ago

An issue with having the legal limit at ~2-5ng/ml is that it makes habitual users be over the limit if they have smoked recently or not.[0] Making the prohibition seem unserious to some, not about safety but about punitive control, and in turn making it matter less if you smoke and drive as you are taking the risk of getting into trouble in any case. The impairments of driving under the influence of alcohol have been extensively studied, but unless I have overlooked the literature it seems that the same investigations have not been carried out with THC. [0] «Blood THC >2 ng/mL, and possibly even THC >5 ng/mL, does not necessarily represent recent use of cannabis in frequent cannabis users.»; https://www.sciencedirect.com/science/article/abs/pii/S0376871620303422 https://www.sciencedirect.com/science/article/abs/pii/S03768...

iLoveOncall 10mo ago
Opening the article would have allowed you to see that the average was 30.7 ng/mL, it's in the very first bullet point!
- tokai 10mo ago
  If you calmed down and stopped snapping at everyone, you might understand that I'm writing about how the law and a lack of studies could make some people more willing to drive high. You are substantially diminishing the quality of the discussion here.
- adgjlsfhk1 10mo ago
  using a mean rather than median is fairly odd here. a mean is pretty much worthless without knowing distribution shape.
- dragonwriter 10mo ago
  The average (presumably arithmetic mean, though it could technically be any of a wide variety of measures) is not particulatly interesting, the median specifically would be more interesting, as a single figure.
  - iLoveOncall 10mo ago
    I partially agree, but it is still relevant, because there is a relatively low upper bound to the values possible after which someone would literally be unable to even walk to their car to start driving. When the average is SO high above the legal limit, and with this constraint that there is an upper bound, it's absolutely relevant.
terminalshort 10mo ago
But the truth is that habitual users are always impaired. Source: former habitual user.
- Sparkle-san 10mo ago
  Got any real sources? I've been a daily user for over 10 years and also have a spotless driving record.
  - formerly_proven 10mo ago
    It is very noticeable to basically everyone when you consume cannabis regularly.
    - tptacek 10mo ago
      I don't (I find cannabis unpleasant) but I don't think this is at all true.
    - pinkmuffinere 10mo ago
      I think serious studies would be strongly preferred here, as compared to anecdotes or conjecture. I don’t even know if I disagree with your stance, it’s just an absence of data is not convincing.
    - throaway123123 10mo ago
      not exactly. Depends how you consume it. Smoking, yes probably. The other forms of cannabis are less obvious. They are clearer highs without smell or smoke and much less burnout.
      - badc0ffee 10mo ago
        Less coughing and effects of smoke, but the burnout is definitely due to daily THC, even if you vape it or do dabs. (To be clear, I don't think every daily user is a burnout.)
shtzvhdx 10mo ago
Even if your point is conceded which I will state as: "the impairment levels are too so that unimpaired habitual pot users appear impaired" 40% of the general population is not a habitual cannabis user. So whether they are "high" or not, folks with high THc levels are dangerous.
marcinpieczka 10mo ago
That works the same with alcohol - heavy alcoholic would probably need to be over the limit to feel ok and sober.
- Aurornis 10mo ago
  An important point is that drug users (alcohol included) lose their ability to judge their own impairment after a lot of habitual use. They can even develop an ability to appear sober to casual observers while being impaired. Feeling sober is not a reliable indicator of being sober. It’s referred to as delusions of sobriety.
Youden 10mo ago
There was a larger discussion in a previous thread on this topic: https://news.ycombinator.com/item?id=45494730 https://news.ycombinator.com/item?id=45494730 Since then, [0] has been published and I think it's worth at least a skim. Since it's quite recent the introduction summarizes some of the most recent research. The things that jump out at me are: - [0]: Habitual users with baseline concentrations above legal limits perform just as well as habitual users with baseline concentrations below the legal limit, indicating that for habitual users, the legal limit doesn't have any relation to impairement. - [1]: A study in Canada analyzed crash reports and blood tests to look at the state of drivers responsible for accidents. While alcohol had a very clear and statistically-significant influence on the risk of a driver causing an accident, THC did not. To steelman the idea that THC causes accidents, [0] only looks at habitual users with baseline levels of THC and [1] only looks at non-fatal injuries. My conclusion right now is that the number of drivers in accidents with THC in their blood is going up because the number of people with THC in their blood is going up, not because drivers who use THC cause accidents. The law's assumption that this level of THC is evidence of impairment seems to be invalid. The law would be better off measuring impairment in some way and perhaps intensifying penalties when an impairment test fails and the user has THC concentration above some threshold. [0]: https://academic.oup.com/clinchem/article/71/12/1225/8299832?login=false https://academic.oup.com/clinchem/article/71/12/1225/8299832... [1]: https://pubmed.ncbi.nlm.nih.gov/31106494/ https://pubmed.ncbi.nlm.nih.gov/31106494/
- seizethecheese 10mo ago
  Sure, but in this study 40% of people had very high THC concentrations. Is it even remotely plausible this is the baseline population level?
  - bookofjoe 10mo ago
    DEAD people
    - graeme 10mo ago
      If the population of dead drivers with over the limit THC is 40%, and this dramatically exceeds the population average, that would strongly suggest the THC level IS an indicator of either: 1. Impairment from THC, or 2. Worse than average driving and risk management skills in those who use the drug
dmitrygr 10mo ago
Perhaps habitual drug users should not participate in operating heavy machinery around people?
- wildzzz 10mo ago
  Should alcoholics be barred from driving as well, even if they are perfectly sober when behind the wheel?
  - dmitrygr 10mo ago
    Statistically, yes they should.
2OEH8eoCRo0 10mo ago
And there are alcoholics who remain highly functional well over the legal limit.
wooger 10mo ago
Yes, you cannot drive if you smoke cannabis at all. Seems fine, now just get them off the road.

by tokai 10mo ago

iLoveOncall 10mo ago

Opening the article would have allowed you to see that the average was 30.7 ng/mL, it's in the very first bullet point!

tokai 10mo ago
If you calmed down and stopped snapping at everyone, you might understand that I'm writing about how the law and a lack of studies could make some people more willing to drive high. You are substantially diminishing the quality of the discussion here.
adgjlsfhk1 10mo ago
using a mean rather than median is fairly odd here. a mean is pretty much worthless without knowing distribution shape.
dragonwriter 10mo ago
The average (presumably arithmetic mean, though it could technically be any of a wide variety of measures) is not particulatly interesting, the median specifically would be more interesting, as a single figure.
- iLoveOncall 10mo ago
  I partially agree, but it is still relevant, because there is a relatively low upper bound to the values possible after which someone would literally be unable to even walk to their car to start driving. When the average is SO high above the legal limit, and with this constraint that there is an upper bound, it's absolutely relevant.

terminalshort 10mo ago

But the truth is that habitual users are always impaired. Source: former habitual user.

Sparkle-san 10mo ago
Got any real sources? I've been a daily user for over 10 years and also have a spotless driving record.
- formerly_proven 10mo ago
  It is very noticeable to basically everyone when you consume cannabis regularly.
  - tptacek 10mo ago
    I don't (I find cannabis unpleasant) but I don't think this is at all true.
  - pinkmuffinere 10mo ago
    I think serious studies would be strongly preferred here, as compared to anecdotes or conjecture. I don’t even know if I disagree with your stance, it’s just an absence of data is not convincing.
  - throaway123123 10mo ago
    not exactly. Depends how you consume it. Smoking, yes probably. The other forms of cannabis are less obvious. They are clearer highs without smell or smoke and much less burnout.
    - badc0ffee 10mo ago
      Less coughing and effects of smoke, but the burnout is definitely due to daily THC, even if you vape it or do dabs. (To be clear, I don't think every daily user is a burnout.)

shtzvhdx 10mo ago

Even if your point is conceded which I will state as: "the impairment levels are too so that unimpaired habitual pot users appear impaired" 40% of the general population is not a habitual cannabis user. So whether they are "high" or not, folks with high THc levels are dangerous.

marcinpieczka 10mo ago

That works the same with alcohol - heavy alcoholic would probably need to be over the limit to feel ok and sober.

Aurornis 10mo ago
An important point is that drug users (alcohol included) lose their ability to judge their own impairment after a lot of habitual use. They can even develop an ability to appear sober to casual observers while being impaired. Feeling sober is not a reliable indicator of being sober. It’s referred to as delusions of sobriety.

Youden 10mo ago

There was a larger discussion in a previous thread on this topic: https://news.ycombinator.com/item?id=45494730 https://news.ycombinator.com/item?id=45494730 Since then, [0] has been published and I think it's worth at least a skim. Since it's quite recent the introduction summarizes some of the most recent research. The things that jump out at me are: - [0]: Habitual users with baseline concentrations above legal limits perform just as well as habitual users with baseline concentrations below the legal limit, indicating that for habitual users, the legal limit doesn't have any relation to impairement. - [1]: A study in Canada analyzed crash reports and blood tests to look at the state of drivers responsible for accidents. While alcohol had a very clear and statistically-significant influence on the risk of a driver causing an accident, THC did not. To steelman the idea that THC causes accidents, [0] only looks at habitual users with baseline levels of THC and [1] only looks at non-fatal injuries. My conclusion right now is that the number of drivers in accidents with THC in their blood is going up because the number of people with THC in their blood is going up, not because drivers who use THC cause accidents. The law's assumption that this level of THC is evidence of impairment seems to be invalid. The law would be better off measuring impairment in some way and perhaps intensifying penalties when an impairment test fails and the user has THC concentration above some threshold. [0]: https://academic.oup.com/clinchem/article/71/12/1225/8299832?login=false https://academic.oup.com/clinchem/article/71/12/1225/8299832... [1]: https://pubmed.ncbi.nlm.nih.gov/31106494/ https://pubmed.ncbi.nlm.nih.gov/31106494/

seizethecheese 10mo ago
Sure, but in this study 40% of people had very high THC concentrations. Is it even remotely plausible this is the baseline population level?
- bookofjoe 10mo ago
  DEAD people
  - graeme 10mo ago
    If the population of dead drivers with over the limit THC is 40%, and this dramatically exceeds the population average, that would strongly suggest the THC level IS an indicator of either: 1. Impairment from THC, or 2. Worse than average driving and risk management skills in those who use the drug

dmitrygr 10mo ago

Perhaps habitual drug users should not participate in operating heavy machinery around people?

wildzzz 10mo ago
Should alcoholics be barred from driving as well, even if they are perfectly sober when behind the wheel?
- dmitrygr 10mo ago
  Statistically, yes they should.

2OEH8eoCRo0 10mo ago

And there are alcoholics who remain highly functional well over the legal limit.

wooger 10mo ago

Yes, you cannot drive if you smoke cannabis at all. Seems fine, now just get them off the road.