Cannabis intoxication in living and deceased drivers is an important medico-legal topic, but only a limited number of studies examine cannabinoids in living and deceased humans. This study compares cannabinoid concentrations (in ng/mL) in driving under the influence of drug (DUID) drivers with blood cannabinoids to those in drivers who died while driving with cannabinoids in their post-mortem (PM) peripheral blood. From 2010 to 2013, there were 318 cannabis-positive DUID cases (mean, median THC: 4.9, 3); 88 had cannabis-only in their bloods (mean, median THC: 5.8, 4). In 23 DUID cases, Huestis' Predictive Models with 95% confidence intervals were applied and evaluated, demonstrating that the actual case time points in all 23 cases fell within the predicted time ranges. Among deceased drivers, 19 had cannabis-positive toxicology (mean, median THC: 11.7, 4.5) and 8 had cannabis-only (mean, median THC: 20.3, 19.5). Motorcyclists and bicyclists comprised the majority of deceased vehicle operators, with bicyclists averaging the highest mean and median THC concentrations overall. The analysis of variance between living and deceased drivers' cannabinoid concentrations showed that THC-OH and THC-COOH concentrations are not statistically different between the two groups, but that THC concentrations are statistically different, making it difficult to directly correlate PM with antemortem THC concentrations between living and deceased drivers.
Drug driving is can be an issue for anyone taking medical cannabis and driving and is probably an issue in the US where people are welded to their cars and also have high availability to medical marijuana. This study tries to see if deaths from driving had any effect relating to drug levels. There are probably too few to make any real conclusions.
It seems that people dying under the influence are cyclists and motorbike riders, and as cannabis is well known to influence balance....Moral of the story don't ride a bike stoned.