4 ms·

I remember reading a story about a Grandmother who ate a strong pot brownie everyday for medical reasons and it had little noticeable effect on her. We know th

I remember reading a story about a Grandmother who ate a strong pot brownie everyday for medical reasons and it had little noticeable effect on her. We know there's a direct correlation between alcohol levels and driving impairment, but I've not seen evidence for this link with THC. Are there studies that have found this? (Please forgive my ignorance...) If someone uses X amount of marijuana (what this tech can establish), do we know that this will always have effect Y on the driver? For example I know people who are heavy marijuana smokers who can smoke a whole joint and you'd never know whereas someone right next to them will take one puff and lose their mind.

dragonwriter 7y ago
> If someone uses X amount of marijuana (what this tech can establish), do we know that this will always have effect Y on the driver? That's not the relation we have with alcohol, either; we have an on-averagr relationship. Which is why drunk driving laws tend to prohibit both being actually impaired by alcohol regardless of BAC and having a BAC over a certain level even without any other evidence of impairment. Drugged driving laws generally prohibit actual impairment due to any drug (including marijuana/THC), without specifying testing thresholds as an alternative basis, largely because we don't have as much testing levels vs. impairment data for other drugs. A test could provide evidence supporting the conclusion that observed erratic behavior was impairment due to the drug without being compared against a fixed “prohibited” threshold.
jaynetics 7y ago
Excellent point. I'm not sure how "fixed" the correlation is for alcohol though. Someone who almost never drinks will be quite impaired at 1‰ BAC, whereas someone who drinks several times a week might not be affected that much. Of course this variation is comparatively small. When it comes to THC, individual resistance really differs by orders of magnitude. Seems the body can adapt to psychoactive agents more easily than to cytotoxins such as alcohol.
- chriscappuccio 7y ago
  At 1% BAC you are dead, dude
SannTek 7y ago
As a few people have mentioned already, there really is not a foolproof correlation between "amount taken" and "degree of impairment" for any drug. Even for alcohol, frequent alcohol users can build up significant tolerance. In general, blood concentrations for THC are pretty good at identifying impairment for infrequent users (greater than 90% predictive in some studies), but are very inaccurate for frequent users with a built up tolerance.
- johnisgood 7y ago
  > are very inaccurate for frequent users with a built up tolerance. Emphasis on this.

dragonwriter 7y ago

> If someone uses X amount of marijuana (what this tech can establish), do we know that this will always have effect Y on the driver? That's not the relation we have with alcohol, either; we have an on-averagr relationship. Which is why drunk driving laws tend to prohibit both being actually impaired by alcohol regardless of BAC and having a BAC over a certain level even without any other evidence of impairment. Drugged driving laws generally prohibit actual impairment due to any drug (including marijuana/THC), without specifying testing thresholds as an alternative basis, largely because we don't have as much testing levels vs. impairment data for other drugs. A test could provide evidence supporting the conclusion that observed erratic behavior was impairment due to the drug without being compared against a fixed “prohibited” threshold.

jaynetics 7y ago

Excellent point. I'm not sure how "fixed" the correlation is for alcohol though. Someone who almost never drinks will be quite impaired at 1‰ BAC, whereas someone who drinks several times a week might not be affected that much. Of course this variation is comparatively small. When it comes to THC, individual resistance really differs by orders of magnitude. Seems the body can adapt to psychoactive agents more easily than to cytotoxins such as alcohol.

chriscappuccio 7y ago
At 1% BAC you are dead, dude

SannTek 7y ago

As a few people have mentioned already, there really is not a foolproof correlation between "amount taken" and "degree of impairment" for any drug. Even for alcohol, frequent alcohol users can build up significant tolerance. In general, blood concentrations for THC are pretty good at identifying impairment for infrequent users (greater than 90% predictive in some studies), but are very inaccurate for frequent users with a built up tolerance.

johnisgood 7y ago
> are very inaccurate for frequent users with a built up tolerance. Emphasis on this.