Researchers analyzed coroner records from Montgomery County in Ohio from January 2019 to September 2024, focusing on 246 deceased drivers

One county, 246 driver’s. Such a weird, small survey with a headline that is sensational.

I was curious if chronic users would be included in this.

From article:

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.

Ohio law (PDF)

Under current law, a person commits an OVI offense (operating under the influence) related to the person’s use of marijuana if the person operates a vehicle or a watercraft and the person:

1. Is under the influence of marijuana (or a combination of alcohol and marijuana);
2. … at least two nanograms of marijuana per milliliter of the person’s whole blood orblood serum or plasma;
3. … at least 50 nanograms of marijuana metabolite per milliliter of the person’s whole blood or blood serum or plasma.

From the Canadian medical association journal:

Our recent systematic review examined studies on blood THC levels in heavy cannabis users following monitored abstinence of at least 4 hours. The findings of our review suggest that chronic cannabis users may have blood THC levels that persist above the per se limits of 2 ug/L and 5 ug/L despite prolonged abstinence (2). A number of studies reported blood THC levels above 2 ug/L that could persist up to 6 days despite abstinence, with the longest reported duration being 30 days (2, 3). In addition, high THC levels of above 5 ug/L over several days is also a significant finding that informs our knowledge of blood cannabinoid concentrations in heavy users during sustained abstinence.

The current interpretation of THC levels in long-term cannabis users may need to be reconsidered based on the evidence that THC levels may be higher and persist for longer than previously described. Some studies have reported a rapid fall in blood THC levels within an hour or two within smoking and a prolonged terminal elimination phase. During the latter, the blood THC concentrations fall to a residual level of up to 2 to 3 ug/L and decline slowly over a week or more (3, 4).

However, the studies included in our review showed that although the plasma THC levels in chronic users generally declines gradually over the course of abstinence, a number of chronic users’ blood THC profile did not follow this classical and predictable pattern. Some subjects had high detectable blood THC levels above 5 ug/L that persist for several days or even weeks, and some users displayed alternating positive and negative samples throughout the course of abstinence.

Furthermore, our review demonstrated that blood THC level may not indicate recent cannabis use in chronic cannabis users, and that users with elevated THC levels above the per se limits of 2 or 5 ug/L may be criminalized despite no recent exposure.

From /u/CrissDarren on Reddit referencing this study:

In summary, they took 25 volunteers who smoke very heavily (up to 10 blunts/day) and have done so for a long time to test. Out of the 25 patients (the majority of whom smoked the day before entering the study), ONE tested above 5 ng/mL of THC the day that the patients entered. I’d say this is very similar to 25 people being ass-wasted the night before and one or two being able to blow over a .08 the next day at noon (I know I’ve been there before).

The following days, nobody tested over 5 ng/mL, meaning that even for the heaviest smokers, you mostly likely have zero chance being over the limit more than one day after smoking. The authors also note that the level of THC is very high directly after smoking (100-400 ng/mL), but quickly drops, often falling below 5 ng/mL within a few hours. So in the vast majority of cases, unless you’re driving an hour or two after getting completely baked (in which case you should walk/take public transit anyways), you should be in the clear.

In this chart figure (PDF), which peaks at around 40ng/ml chronic users are at 10ng/ml at 1 hour.

So unless I’m missing something either 32% of drivers were pretty much crashing within the first half hour of smoking, some outliers were super fuckin baked in this small sample study, or their test included metabolites and then could capture chronic users that weren’t actually intoxicated. Also the laws on this are fucked so multiple times the state law is not really saying anything. Nice.

40% is not a lot. I fail to see the point here