r/science Oct 06 '22 Gold 1

Scientists are a step closer to their goal of developing a handheld tool similar to an alcohol Breathalyzer that can detect THC on a person’s breath after they’ve smoked marijuana Chemistry

https://newsroom.ucla.edu/releases/step-toward-a-marijuana-breath-analyzer
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u/Chadly80 Oct 06 '22

I read the whole article two pieces of information were missing. How long after smoking is it detectable? and how did that correlate with impairment if driving? Without answering those questions this is nothing but a fluff piece.

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u/Hindukush1357 Oct 06 '22

That’s one of the biggest issues. What level of thc equals impairment?

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u/dwellerofcubes Oct 06 '22

That differs between individuals and varies widely. So yeah, this is useless except as a zero-tolerance device, which means it's going to require significant further development to be of use to most jurisdictions.

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u/SFXBTPD Oct 06 '22

That differs between individuals and varies widely

So does alcohol and we still have guidelines for that.

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u/Larry_Mudd Oct 06 '22 edited Oct 06 '22

Cannabis is different in that there's currently no reliable way to determine if you're intoxicated at all with a roadside test.

Here in Canada, cannabis has been legal for four years and the current legislation sets the threshold for DUI at 2ng per ml of blood.

This sounds good because it's a nice discrete number, but the problem is that it's totally disconnected from actual intoxication.

I would never drive while high because I'm not an idiot (at least in this regard) but as it stands I'm almost certainly over that limit whenever I drive somewhere in the morning, because I usually take some edibles after supper every night, and then a little more before bed. It's maybe a three hour buzz but when I get up in the morning I'm technically over that limit even though I am 100% clear-headed.

I never worry about this because I'm fortunate enough to be in a demographic that doesn't get hassled by the cops and don't expect to ever have to submit to a test but it's not a great situation where people who are absolutely not impaired may end up with a DUI anyway, especially if they're in a demographic that does get regularly singled out.

ETA: Link to study showing >2ng/ml of THC can persist in blood for weeks after use, during which you may get an automatic DUI conviction in Canada

We definitely need a test that is more useful for determining intoxication, because the idea that someone is unsafe on the road because they were high a couple days ago is absurd.

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u/MeatSafeMurderer Oct 07 '22

Cannabis is different in that there's currently no reliable way to determine if you're intoxicated at all with a roadside test.

The big question that immediately occurs to me is...if there's no reliable way to determine that you're intoxicated...then does it even matter? If it's not possible to tell that someone is intoxicated then their motor function and decision making clearly are not particularly impaired.

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u/Larry_Mudd Oct 07 '22

I mean, people can clearly have their performance impaired by cannabis. Anecdotally, the last time I took someone at their word when they said they were fine to drive a while after smoking (nearly thirty years ago) that person demonstrated their caution by avoiding busy streets, but got so absorbed in a story he was telling us that he turned around 180 degrees to regale us backseat folks and failed to observe the car in front of us observing a stop sign.

...but the problem is that we can't measure that impairment; we can only measure metabolites. Fairly clear that doing bong rips and driving should be illegal as a matter of public safety, but really awkward right now because the best testing available can't distinguish between current intoxication and use from days ago.

In an ideal world, people are only having to submit to the test because a LEO earnestly believes they are high - but it's possible that people might get saddled with impaired charges according to an individual's whimsy or prejudie.

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u/Minute-Tale7444 Oct 07 '22

As someone who’s gotten DUI convictions like this in the USA (indiana), it’s definitely a problem. A regular user’s THC levels can vary greatly upon each person, the type of weed, and the length of time since consumption. This just isn’t a practical devicE.

ETA-I wasn’t driving after I’d just smoked btw. It’s seriously just because it was in my system at all I’ve gotten two DUI charges.

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u/murdering_time Oct 06 '22

Alcohol tolerance is not the same as cannabis tolerance due to the fact that cannabinoids are fat soluble. You really have to be an everyday drinker to not be phased by a .08 BAL, but you don't have to smoke weed every day to get your tolerance up to the point where you can smoke a few bowls and be perfectly functional.

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u/ZachTheCommie Oct 06 '22

It's truly incredible how much the effects change with tolerance. If you smoke once in a while, you're practically useless when you're high. But if you smoke regularly, and get your dosage right, the impairing side effects are negligible.

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u/Nuclear_Sister Oct 06 '22

Yes and no. I'm a daily user (edibles, not smoke) and sometimes the same dosage hits different. I'm highly functional when moderately stoned but I still avoid driving when high no matter what as I do still feel effects. I'm familiar with the effects and can function when feeling them but for things like driving and working I wouldn't say the impairment is negligible, I'm still in an altered albeit functional state.

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u/Jacollinsver Oct 06 '22

If I don't smoke regularly, smoking results in a panic attack 99% of the time. If I smoke regularly, I only have panic attacks 98% of the time, so it's a good thing I smoke constantly.

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u/Draydyn- Oct 06 '22

Sounds like some shadow work is in order.

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u/Jacollinsver Oct 06 '22

I don't know what that means but I imagine if we met in person you'd be wearing a hooded cloak of black velvet and pointing me towards a door that wasn't there a moment before

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u/Draydyn- Oct 06 '22

Your insight is very aligned.

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u/haporah Oct 07 '22

Try to smoke a very small amount at a time. Should help with the panic.

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u/OCE_Mythical Oct 06 '22

Yep that's what I wonder too, it's all well and good to have a breathalyzer until you get done for smoking on the weekend and it's a Tuesday.

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u/danbln Oct 06 '22

I suspect quite a high level, for most levels tested in studies I've read, the drivers actually seemed to drive slightly safer despite decreased reaction time compared to control.

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u/Col_Leslie_Hapablap Oct 06 '22

I mean, that same question can be posed about .08 for alcohol. There does need to be a baseline.

Some people are absolute machines (or alcoholics) and even with a BAC of .08 feel next to no effects at that level, and some people are off their ass at that point. The one thing I hope we can get away from with THC is measuring it when someone hasn’t smoked for more than 24 hours being exposed to impaired driving charges. Because it’s not like alcohol or many other drugs, and can appear in a person for many hours/days after they ingest it, it’s important to get this right.

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u/LakerUp Oct 06 '22

There are no definitive cannabis impairment studies that can make this correlation. Alcohol impairment can be quantitatively measured because we have exhaustively examined the quantity of alcohol in the blood which causes impairment in all humans, regardless of tolerance or individual physiology. Cannabis cannot be quantified this way because it’s impairing effects on individual persons are widely disparate. That is never going to change. The only way to objectively measure cannabis impairment is through a combination of field sobriety testing and a drug recognition examination. And even then subjectivity remains depending on the skill level of the examiner.

https://www.theiacp.org/drug-recognition-experts-dres

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u/igot_it Oct 06 '22

This is correct. Further complicating things is the rapid onset and excretion of alcohol and it’s permeability of the blood brain barrier. Basically your bal correlates directly to the amount of intoxicant in the brain. Drugs in your blood don’t get you high. It’s when it affects the brain that intoxication occurs. Currently there is no test for thc levels in the brain….roadside spinal taps anyone?

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u/LakerUp Oct 06 '22 edited Oct 06 '22

Yes, certainly another complication. The article the OP posted also makes several errors. They conflate carboxy THC, a non-psychoactive cannabis metabolite (cannot cause impairment), which can remain in a persons system for weeks and Delta-9, the psychoactive compound that does cause impairment. Delta-9 metabolizes and generally disappears from the blood within hours. They never reference this distinction, which is troubling and makes me question their other claims, Does the device actually distinguish between carboxy THC and Delta 9? If not, it is effectively no better than delayed blood testing for a mixture of carboxy THC metabolites and Delta-9. And again, there is widely disparate metabolization of Delta-9 among individuals. We can quantify alcohol impairment primarily because ethyl alcohol is metabolized at an extremely predictable rate range across all individuals. Not so with THC.

And as you illustrated, even if this new road side breathalyzer can measure Delta 9 only, how is it measuring the amount of Delta-9 affecting the central nervous system? This test is is not only not measuring blood levels, it’s not measuring brain levels.

Edit: Sometimes there is no “fair.” I believe this device will not only result in a drastic uptick in DUI arrests, but it will result in the prosecution of thousands who are not impaired even slightly. Marijuana DUI arrests are relatively rare, especially as compared to alcohol DUI’s. It should remain that way if equitable enforcement is the goal. Our justice system is supposed to place the presumed possibility of innocence far before the elevated opportunity to catch those who are guilty.

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u/no-personality777 Oct 06 '22

And then there's delta 8 that also gets you high.

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u/kaddorath Oct 07 '22

And THCO and HHC and THCP and even CBN (though by a very small margin).

I don't smoke at all anymore but dang, there's too many confounding variables at play for anything to be remotely accurate in a "current state of intoxication" with THC.

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u/LakerUp Oct 07 '22 edited Oct 07 '22

Yes, there are over 100 cannabinoids. Delta-9 is the primary psychoactive compound however. Delta-8 is much less pronounced. And the others even less so. And obviously not all are psychoactive. We cannot accurately measure the rate any of them metabolize in the manner we can quantify ethyl alcohol, which is the primary reason having a per se limit like alcohol (.08 in most states) is bananas. Not the only compelling reason though.

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u/Sir_Squirly Oct 06 '22

Most places use “within 4 hours” as a standard, with having 0 science to back impairment vs time.

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u/[deleted] Oct 06 '22 edited Oct 07 '22

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u/UEMcGill Oct 06 '22

In NY state, you are under no obligation to take any field sobriety tests. Hand held breathalyzers are not the legal standard of proof, they only prove reasonable suspicion. It's also why you should know your local laws, because most states have something similar. BUT, in NY they can take you in and you have to take either the official breathalyzer or a blood test. You also have the right to call your lawyer as long as you request him by name.

So they don't need to prove impairment in NY, only reasonable suspicion. Once they get a blood test? It doesn't matter.

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u/FloydKabuto Oct 06 '22

If a cop has one of those on him getting caught driving with any THC on your breath will be a DUI regardless. They already do it with a breathalyzer and the walk just for show.

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u/SerenityViolet Oct 06 '22

And what about passive smoking.

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u/futatorius Oct 06 '22

No evidence it causes impairment. May be detectable though.

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u/BookDumb-StreetDumb Oct 06 '22

This ambiguity can lead to fines, imprisonment or loss of employment, even if an individual is not high when tested.

You'd think that what would be most "fair" is the police choosing not to include the results of a potentially unrelated drug test in the evidence in the first place. One less method to be able to fine and jail your population that way, though, so we know that won't happen.

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u/[deleted] Oct 06 '22

If you end up getting a urine or blood test as a result of a traffic stop the police already think you’re impaired. That evidence of impairment, whether accurate or not, is going to be included in evidence because it supports the policeman’s claim that you are impaired.

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u/BookDumb-StreetDumb Oct 06 '22

whether accurate or not, is going to be included in evidence because it supports the policeman’s claim

That's exactly the problem. When evidence is considered not because of its merit or accuracy, but only because it can be used to support the state's case against you, you have yourself a corrupt police state.

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u/GenitalJouster Oct 06 '22

How could they even write that out without stumbling over the absurdity of including unreliable evidence just because it serves the head canon of the officer?

It's like stopping someone with an empty beer bottle rolling around in their car and then arresting and incarcerating them on the assumption that the driver definitely drank it right before driving and was thusly driving intoxicated without proof of akute intoxication at the time of driving.

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u/Hindukush1357 Oct 06 '22

You described an actual dwi arrest.

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u/GenitalJouster Oct 06 '22

Unexpected but sadly not really surprising. Hope you guys figure it out

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u/VegetableMindless260 Oct 06 '22

Yeah he's not even joking, if you have an open beer can in your car, even if it's empty and has been for weeks, they'll assume you were drinking while you drove basically. It's seriously ridiculous.

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u/Phog_of_War Oct 06 '22

But if you drank it 5 min ago and tossed the empty in the bed of your pickup, you'd be ok?

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u/VegetableMindless260 Oct 06 '22

As long as they don't think you're impaired and don't check because of that, then yes.

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u/kegatank Oct 06 '22

Open container laws are kinda like this. You can get your license suspended and possibly jail time just for having an open alcohol container in a moving vehicle

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u/kingjoedirt Oct 06 '22

When evidence is considered not because of its merit or accuracy, but only because it can be used to support the state's case against you, you have yourself a corrupt police state.

That kind of ignores the fact that the defense also has the opportunity to discredit evidence and present their own. It's designed to be adversarial for that reason.

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u/quantumOfPie Oct 06 '22

They're going to discredit the word of police office in the eyes of a judge?

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u/Wind_Responsible Oct 06 '22

Yep. If they've gotta test an impaired driver atleast make the test as fair as possible

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u/Tyrilean Oct 06 '22

The problem will be that the legal system is slow to change for new tech. They still use fingerprinting lie detector tests, despite neither having any scientific basis. Why? Because juries believe in them and it makes convictions easier.

Similar here. If they can throw the book at more people for failing a piss test, they’re going to be reluctant to use a tool that results in less convictions.

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u/wetgear Oct 06 '22

Agreed on lie detector but what’s unscientific about fingerprints? Current THC tests don’t test for current THC levels so you could get more conviction of the actively high.

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u/Adventurous_Ad4950 Oct 06 '22

So what about edibles and vape?

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u/[deleted] Oct 06 '22 edited Oct 07 '22

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u/Niceotropic Oct 06 '22

I was product development manager for a hand-held cannabis testing device, and was a Co-Investigator for a NIH National Institute of Drug Abuse grant on the device.

Very early in the process it was clear that breath-based methods would not be possible given the complex nature of the breath and the low vapor pressure of THC and THC metabolites. They are not like alcohol. This is why you don't have "breathalyzer" testing for opiates or "breathalyzer" testing for your blood labs.

Ethanol on the breath accurately reports blood levels. This is not true for other chemicals, like THC. This will not, and cannot work, and is nothing but a reasonable-sounding thing we all want - but is largely a boondoggle.

Saliva testing or blood testing will be the only way to determine this, and even then it has its accuracy problems. The fairest test is probably saliva testing, but this will only cover vaping and smoking weed, and would need a lot of research to work for edibles.

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u/SubzeroNYC Oct 07 '22

yeah I have trouble seeing how any of this stands up in a court of law anytime soon with a halfway decent lawyer

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u/[deleted] Oct 06 '22 edited Oct 06 '22 Gold Vibing

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u/bremarie03 Oct 07 '22

Maybe scientists should stop being fuckin’ narcs.

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u/thenotoriousDEX Oct 06 '22

Well that’s what is interesting. If you are prescribed something like Alprazolam or oxycodone you can drive around completely intoxicated and it’s basically undetectable.

People who take Z drugs to sleep are still impaired in the morning after driving to work and plenty of studies show this. It’s only ever brought up AFTER the fact. When an accident takes place and an investigation is underway.

You usually need to cause an accident and then they test your blood and find out how high your plasma levels are and this usually only happens during fatal accidents because enough time passes to clear it out of your system in other situations.

Unless you are completely obviously visibly intoxicated it’s just not on law enforcements radar.

People who take these drugs daily are accustomed to them and probably think they “drive better on it than without it” much like alcoholics. But research proves otherwise.

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u/ravenhair29 Oct 07 '22

It's such a dishonest development. The whole "religion" that alcohol has to be the same as cannabis is completely false and misplaced. I know from experience that a tumour patient receiving 1000 mg of active THC a day can function perfectly normally. Nobody can function well on a superhigh level of alcohol. The mechanisms are totally different. The roads authorities in the UK, US and Australia have tested this, and yes, the cannabis drivers did slightly better than sober drivers, but not a lot. Alcohol, not so much. As posters here said, this is only intended as a sort of Republican-minded zero-tolerance device, a way of terrorizing the population at large. It has nothing to do with safety or any kind of reasonable administration.

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u/HeyLookItsChicknButt Oct 07 '22

Do you have a link?

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u/ravenhair29 Oct 08 '22

Here is an example - it's very recent, but not the best, as consumption was 'ad libitum' (i.e. whatever you like) instead of limited amounts. Your own research will uncover the best resources.
https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2788264

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u/SkunkMonkey Oct 06 '22

The whole basis for the need of these tests is a sham. They do not indicate if you are impaired enough to drive, only some arbitrary number that's the same for everyone. Everyone is affected differently and someone that can test for over that arbitrary number can drive just fine while someone under that number can be a danger on the road.

How about we test for actual impairment not some arbitrary value?

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u/TheGeneGeena Oct 06 '22

This is pretty much the same issue with alcohol though. Not everyone will have the same level of impairment at a 0.08 BAC either - but judging by impairment alone would be up to the arbitrary determination of the officer on scene, which would likely be a much worse system.

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u/Buick_reference3138 Oct 06 '22

But that is what they do. First they look and if they see signs of impairment or you fail a field sobriety test THEN they ask you to take a breath test, they don’t usually breath test if you pass all the field tests

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u/AlmightyStreub Oct 06 '22

If you're out of the car walking heel to toe then you're almost certainly blowing into the roadside breathalyzer.

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u/Jaded_Prompt_15 Oct 06 '22

but judging by impairment alone would be up to the arbitrary determination of the officer on scene, which would likely be a much worse system.

What do you think happens now?

Have you never seen any of the articles about politicians or cops being drunk, causing an accident, and then being sent home without a breathalyzer?

Hell, when that one AG out of one of the Dakota's (I think) killed a guy, cops let him drive one of the responding cop cars home instead of giving him a breathalyzer

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u/TheGeneGeena Oct 06 '22

The corruption of police with regards to public officials is part of the point I'm making - that same corruption can swing in the other direction with regards to every day citizens.

A breathalyzer is at least a measurable benchmark - I'd prefer it not be my word against a small town cop's over a DUI.

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u/iamansonmage Oct 06 '22

They just need to convice a jury that their machine is trustworthy and every time the machine beeps they can send another person to jail. They only want an arbitrary value and they certainly don’t want people pointing out the flaws in they “go directly to jail” device!

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u/Gareth009 Oct 06 '22

For alcohol, in California, the maximum legal blood alcohol content is .08% while driving. What level of THC is illegal?

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u/dethily Oct 07 '22

Why tf they waisting money on this?

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u/Kandorek Oct 07 '22

this might stop cops from lying that they "smelled marijuana" to use it as a base to harrass people

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u/hazpat Oct 06 '22

So they just ignore studies that demonstrate MJ has little effect on driving,

Compton RP, Berning A. Drug and Alcohol Crash Risk. Washington, DC: National Highway Traffic Safety Administration; 2015. DOT HA 812 117.

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u/CustosMentis Oct 06 '22

That is not what the study says. That study, and every similar study, says that there is little correlation between levels of THC in the blood and driving ability. The reason being that THC is a lipophilic substance, after you smoke it, THC goes into your bloodstream and quickly leeches into the fatty tissues of your body. So, a blood sample is actually a very poor way to test for THC because it doesn’t stay in your blood very long. As opposed to alcohol, which stays in your blood at roughly equal amounts throughout your body, so a blood sample is a great way to test for alcohol concentration.

Marijuana makes you bad at driving, thats just obvious and common sense. This study is pointing out by blood testing isn’t a good way to measure that impairment, unlike alcohol.

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u/tylerpressey Oct 07 '22

Weed affects you like benadryl affects people, when you first take it yeah the effects are noticeable and intense and compromising but after you have a tolerance the effect just becomes a default state and you kinda relearn how to function and do things, not like alcohol, after smoking regularly for a few months you wouldn't be anymore impaired driving high than you would if you needed a nap, anyone on here claiming people say they can't drive high have never smoked regularly and probably think the initial "high" is what it's like everytime when it's absolutely not. You could take a stoner and a professional driver whose never smoked before and have them both smoke a bowl and the stoner would drive better guaranteed because he lives and functions on it, basically it would be absolutely pointless and unfair to label a baseline legal THC level for driving because everyone's different, this technology is just going to be used as a weapon in the war on drugs because prisons still need laborers.

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u/Artificial-Human Oct 06 '22

Even if they can develop an accurate THC breath test, they’ll have to correlate THC intoxication to THC levels in the blood. Establishing an objectively reasonable, scientific “legal limit” for THC intoxication like what has been done for alcohol.

If my memory is accurate, it took the NTSB 17 years to conduct the testing needed to establish a blood alcohol level of 0.08 as the legal limit for alcohol concentration while operating a motor vehicle. The NTSB had to conduct trials and testing on thousands of people. This is what led to nation wide DUI laws in the 70’s.

Marijuana’s effect is much more subjective than alcohol. Also, with marijuana being illegal federally, I don’t know how they can establish a national standard the same as what was done for alcohol.

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u/MonsterRider80 Oct 06 '22

Not to mention how long THC stays in your body. I like to smoke a joint at night, chill out and go to bed a little later. I’ve been doing this for almost 20 years. I’m afraid of these tests considering I’d probably test positive even if I don’t smoke for a week.

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u/lemmefixu Oct 06 '22

What?

Amphetamines Benzodiazepines Delta-9-tetrahydrocannabinol (THC (cannabis)) Cocaine Methamphetamines Opiates Methadone Ketamine​

This tool is already in use with some police forces. It’s used as a screening device, if positive the driver gets taken to a hospital to quantify the amount in its system.