Driving Under the Influence of Marijuana Versus Driving and Dying Under the Influence of Marijuana: A Comparison of Blood Concentrations of Δ9-Tetrahydrocannabinol, 11-Hydroxy-Δ9-Tetrahydrocannabinol, 11-Nor-9-Carboxy-Δ9-Tetrahydrocannabinol and Other Cannabinoids in Arrested Drivers Versus Deceased Drivers

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 postmortem (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.