Volume 28, Issue 4 (October 1983)
Measurement of Δ9-Tetrahydrocannabinol (THC) in Whole Blood Samples from Impaired Motorists
The major psychoactive cannabinoid in marihuana, Δ9-tetrahydrocannabinol(THC) was measured in 1792 randomly selected blood specimens from erratic motorists arrested for impairment who submitted to blood alcohol sampling. Of these specimens, 14.4% were positive for THC (5.5 ng/mL). In those erratic driver specimens negative for alcohol THC positives rose to 23%. Drivers who used marihuana covered a broad age range. Aliquots of hemolyzed blood (10 μL) were analyzed by a sensitive radioimmunoassay (RIA) not requiring extraction. RIA accuracy and specificity were validated by gas liquid chromatography/mass spectroscopy (GLC/MS) split pair analysis (correlation coefficient = 0.93). This initial experience should facilitate and amplify a program designed to set forth the epidemiology of marihuana use in motorists and possible behavioral correlates.