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Over 40% of deceased drivers in vehicle crashes test positive for THC: Study

Over 40% of deceased drivers in vehicle crashes test positive for THC: Study

bookofjoe

Comments (493)

  • tokai
    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/S03768...
  • michaelteter
    This seems like an intentionally misleading title, since they don't mention that the study was for one county (Montgomery County) in Ohio, which is basically just Dayton, OH and surrounding rural area - < 600k people.I'm sure you can pick other counties in the US which have either very high representation of THC users or very low representations. Without knowing how other counties score in terms of driver fatalities and THC, this is not really very useful.To me it sounds like an effort to paint THC as big and scary. But in my experience living in a few large cities, weed is rare - but lots of people go out, drink, and drive home one or more times per week.ScienceDaily goes even further by rounding up to 50% and burying the location halfway down the summarization."Nearly half of drivers killed in crashes had THC in their blood THC-impaired driving deaths are soaring, and legalization hasn’t slowed the trend. Date: October 5, 2025 Source: American College of Surgeons Summary: Over 40% of fatal crash victims had THC levels far above legal limits, showing cannabis use before driving remains widespread. The rate didn’t drop after legalization, suggesting policy changes haven’t altered risky habits. Experts warn that the lack of public awareness around marijuana’s dangers behind the wheel is putting lives at risk."Unless they publish who funded the study, I'm skeptical that the alcohol industry might be involved. It's absolutely in their best interest to paint marijuana as the devil (and take attention away from alcohol).Obviously nobody should be driving with any impairment, but people do - driving tired, texting, even talking to passengers and turning their heads to look at the passengers while they talk! (Really, why??? I see people doing this all the time.)
  • Aurornis
    Some helpful context: The number of Americans age 12 and older who report using any marijuana product at least once in the past year is around 20% (Source https://apnews.com/article/marijuana-cannabis-alcohol-use-di... ) if I use one of the highest reported use numbers I can find.Even if you dismiss all of the questions brought up in these comments like the use of mean levels instead of median, not accounting for tolerance of habitual users, or debates about the threshold for impairment, the 40% number in this study is without a doubt far higher than the number of people who have detectable levels of THC in their blood at any given time.I see a lot of attempts to downplay the result of this study in the comments, but 40% having significant THC in their blood is a stunning statistic no matter how you look at it.
  • Someone
    > In a review of 246 deceased drivers, 41.9% tested positive for active THC in their blood, with an average level of 30.7 ng/mL — far exceeding most state impairment limits.That could mean they all had levels far exceeding most state impairment limits, but it also could mean most of them had trace levels, while a few had levels way above 30.7 ng/mL. So, it says fairly little.Also (FTA) “Researchers analyzed coroner records from Montgomery County in Ohio from January 2019 to September 2024, focusing on 246 deceased drivers who were tested for THC following a fatal crash”. That means there could be selection bias at play.Finally, no mention is made on the levels of THC in the general population of of those driving cars. Both _could_ be equal or even higher.I’m not sure one should blame (only) the researchers for these statements, though. Chances are they didn’t intend to find out whether THC use is a major cause of vehicle crashes, but only in whether legalizing THC use changed those numbers, and someone managed to get some more juicy quotes from them.
  • epistasis
    Based on the headline, I was guessing it was any amount of positivity, and may be close to the population level, but it's actually impairment levels of THC:> In a review of 246 deceased drivers, 41.9% tested positive for active THC in their blood, with an average level of 30.7 ng/mL — far exceeding most state impairment limits.Since COVID in CA, it feels like driving has become far more dangerous with much more lawlessness regarding excessive speeding and running red lights, going into the left lane to turn right in front of stopped cars, all sorts of weird things. But I can't tell if my anecdotes are significant. It seems that Ohio's impaired drivers have been consistent through the past six years though.
  • 3eb7988a1663
    Wish the paper were available - would love to know the percentage with alcohol.The other question I have - my prior is that a bad driver (tired, drunk, high) is something like 70:30 odds of killing themselves vs some innocent bystander dying because of their actions. I have anecdotally heard of several sad tales where some guy is on his Nth DUI and kills an entire family, while he walks away from the accident without a scratch. Meaning are the rates of fatalities involving THC actually higher, but the detectably inebriated person managed to walk away without dying.
  • jjice
    Feels like a low sample size, but I'm not statistician or doctor.That said, almost everyone I know that consumes THC has no qualms driving while doing it, and many of them also at work. It's a huge peeve of mine.
  • hereme888
    Serum levels of THC do not correlate with degree of impairment. It's not linear, like alcohol.I thought this was common knowledge among physicians who have studied the subject.
  • bloppe
    Anybody who's smoked a lot of weed knows that THC tolerance works very differently from alcohol tolerance. If you've been ripping dabs every couple hours for the last month, you might be well above the legal limit and barely feel different at all. On the other hand, if you haven't smoked in a year and take a single hit of a modern joint, you could be floored.I'm not sure how THC intoxication could be measured, but blood THC concentration feels like an incredibly crude metric compared to BAC.
  • teddy-smith
    Whenever you think to yourself "People couldnt be that stupid, right?" read this study and plan accordingly.
  • neoCrimeLabs
    I am curious what percentge of the general populous test positive for THC. It would give better context to a dead drivers testing positive for THC.
  • laughing_man
    >The rate of drivers who tested positive for THC did not change significantly before or after legalization (42.1% vs. 45.2%), indicating that legal status did not influence the behavior of those who chose to drive after use.That being the case, I'm not sure what the policy prescription should be here, if any.
  • Youden
  • ck2
    I live in a "working poor" neighborhood50% of the people on this street get stoned before driving to work, every single daydope isn't even legal here and even if it was DUI is wildly illegalWe can only cure this if we get serious about penalties because we can't undo murder and injuriesHow about first time warning, second time weekend in jail, third time week in jail, fourth time month in jail, fifth time year in prison
  • mchusma
    Self driving cars can’t come fast enough to save lives. I’d love to have states start today at cracking down on unsafe drivers of all kinds. I suspect that converting just 10% of miles to self driving + getting rid of 10% most unsafe drivers would reduce fatalities 50%.
  • ChrisMarshallNY
    I have a friend that's a mechanic.He says that he gets cars in that reek so bad, he can smell them from three bays away.I suspect that we'll soon be seeing a rapid "pullover-test," and that will probably knock that stuff down.
  • golem14
    It will be interesting to read the actual study when it comes out.Interesting questions: * What is the baseline of consumption / THC level?* what was the alcohol level in decesased drivers ? (e..g how many people only had alcohol, how many only THC, how many had both, how many had nothing.* Are there other test scenarios where THC screening is mandatory that could help getting to the baseline ? Are there ways to get an approximate answer from sewers, like they did for Covid?
  • flaminHotSpeedo
    > Researchers analyzed coroner records from Montgomery County in Ohio from January 2019 to September 2024, focusing on 246 deceased drivers who were tested for THC following a fatal crash.This paper would need to go into way more detail to be at all useful.40% is a staggering number, which makes me suspect that all it measures is Montgomery County police's pretty good track record for deciding when to test someone for THC during an autopsy
  • m463
    I saw this and it was too funny: Over 40% of deceased drivers in vehicle crashes test positive for THC: Study (facs.org) 281 points by bookofjoe 15 hours ago | flag | hide | 420 comments =============
  • derriz
    There is no mention that these drivers were ONLY impaired by weed. But I can’t believe a paper would not look at the confounders. I know quite a few who are not regular smokers but will imbibe after a few beers if it’s being passed around. Also weed is popular with consumers of stimulants. Without knowing the possible confounders, this statistic tells you very little.
  • cess11
    Is there a full study somewhere? I'd expect them to screen for other psychoactive substances as well, of which I see no mention here.
  • bobro
    One useful point of comparison here would be the percent of the driving population overall who have some THC in their system in the same way as these researchers are measuring it. I wouldn’t guess that 40% of drivers would test positive for recent THC use, but I can’t understand the 40% number here without knowing the percent for the overall population.
  • PlunderBunny
    Here in New Zealand we’ve just started road-side testing for drug-driving [0]0. https://www.rnz.co.nz/news/national/581951/first-day-of-road...
  • anon
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  • Merrill
    Rather than trying to draw policy conclusions from an epidemiological study like this, wouldn't it be more accurate to give drivers measured amounts of THC, put them in a driving simulator, and measure their performance?
  • supersparrow
    “Unaffected by legalisation” - so at least there’s more proof than outlawing drugs doesn’t work.
  • econ
    You wouldn't expect sober people to be more likely to die.
  • leke
    My question is, what is the difference in vehicle death mortality since cannabis was legalized in those parts of the country. If it's about the same, it just tells me that cannabis is a very popular drug.
  • 8organicbits
    The lack of change after legalization of recreational use is interesting. How many deaths related to medical use versus (previously illegal but decriminalized) recreational use?
  • sfink
    Don't be so judgemental, dying is traumatic! Who wouldn't want a little somethin' to take the edge off?
  • witte
    This feels like we’re missing a dimension or threeve, the one that comes to mind immediately would be whether or not the deceased driver was at fault for the incident.
  • pogue
  • anon
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  • SilverElfin
    I’m not surprised so many deceased drivers were under the influence of THC. I see people smoking and vaping at stoplights all the time. I am however, surprised this study claims legalization didn’t change the rate. Anecdotally, on the west coast, I’ve seen far more of this, and also people casually smoking in public spaces (parks or train stations or whatever) since legalization.
  • anon
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  • casey2
    The sign of a brittle system is constant feeling to restrict user freedom
  • hermannj314
    I need to know the rates in the general driving population before I can assume driving high is dangerous.
  • throw20251220
    That may mean a lot of things. Maybe non-smokers got good at eliminating people who recently smoked.
  • scythe
    >An average level of 30.7 ng/mL generally means those people must have consumed marijuana at some time close to driving.Averages do not work that way! The average of 48, 48, 48, 3 and 3 is 30. The study findings remain interesting but the actual proportion of impaired drivers may be less than 40%.
  • graycat
    I have it on good authority and a lot of data that over 40% of deceased drivers in vehicle crashes test positive for recently having (i) breathed air containing oxygen, (ii) drank tap water (iii) were wearing shoes, (iv) had used those shoes to get to the car, ...
  • cubefox
    Could this mean that THC is more dangerous for vehicle safety than alcohol?
  • mperham
    Phones are by far the biggest source of dangerous driving.
  • iLoveOncall
    And what share of the remaining 60% were killed by the initial 40%?
  • IAmGraydon
    Does anyone else constantly smell weed while driving around? Several times per week I find myself behind a car that wreaks so bad of weed that I can clearly smell it driving a few car lengths behind. I have to wonder…if so many people are smoking enough to smell it in another car while moving, exactly how many people on the road are high?
  • skywhopper
    This stat beggars belief. I think the headline is phrased incorrectly, and the overall stat is misleading. The actual stat is only from dead drivers who were tested for THC. Researchers analyzed coroner records from Montgomery County in Ohio from January 2019 to September 2024, focusing on 246 deceased drivers who were tested for THC following a fatal crash. When autopsies are performed, drug screening is typically part of the process. The unanswered and unaddressed questions here are, how often and why were the THC tests administered? The article says that’s standard for autopsies. But how often are autopsies conducted on deceased drivers? I would be truly surprised if it’s 100%. In fact, I would expect it to happen only in cases where there was some suspicion of intoxication. In which case, this finding isn’t very surprising after all.
  • theturtle
    [dead]
  • kenfichtler
    [dead]
  • morpheos137
    The push for marijuana normalization has been one of the stupidest things in recent memory. It's a drug as harmful as alcohol or nicotine if misused.
  • amazingman
    Cant wait for this tissue-thin abstract to drive weeks and years of anti-cannabis nonsense.
  • codr7
    I bet 100% of them had been drinking water recently.
  • blell
    Remember when people in this web site would blame the recent increase in accidents on the supposed cognitive decline from COVID and how hooked we are on our phones because of the evil tech companies.
  • reactordev
    Just noting there’s a difference between THC in your system and THC in your blood. THC leaves the bloodstream after your high. Goes into fat cells and other areas to be broken down and processed (up to a month) later. Having it in the bloodstream after an accident means they were intoxicated at the time according to science. Whether their CB1 receptors were letting it through is another matter. I can smoke a lot of weed and not “feel high” yet I would test off the charts on this test.For drunk drivers it’s rather easy to assess whether someone is impaired. With marijuana it’s not. So until we have a valid method of testing if someone is “too stoned to drive” we have to push back on any attempt to classify marijuana users as ineligible to drive.