Prevalence of Cannabidiol, ∆9- and ∆8-Tetrahydrocannabinol and Metabolites in Workplace Drug Testing Urine Specimens

Abstract

Given the recent popularity of cannabidiol (CBD) use and the emergence of ∆8-tetrahydrocannabinol (∆8-THC), the prevalence and concentrations of these and other cannabinoids were investigated in 2,000 regulated and 4,000 non-regulated specimens from workplace drug testing. All specimens were screened using liquid chromatography coupled to mass spectrometry (LC-MS-MS) for the presence of 7-hydroxy-CBD (7-OH-CBD) and ∆9-tetrahydrocannabinol-9-carboxylic acid (∆9-THC-COOH), with a cutoff of 2 ng/mL. Specimens screening positive by LC-MS-MS were analyzed by immunoassay at 20, 50 and 100 ng/mL cutoffs and by an LC-MS-MS confirmation method for 11 cannabinoids and metabolites with a 1 ng/mL cutoff. Using a 1 ng/mL cutoff, 98 (4.9%) regulated and 331 (8.3%) non-regulated specimens were positive for ∆9-THC-COOH. Of these, 64% had concentrations below 15 ng/mL. Similarly, 59 (3.0%) regulated and 162 (4.2%) non-regulated specimens were positive for 7-OH-CBD (n = 210), CBD (n = 120) and/or 7-carboxy-cannabidiol (CBD-COOH, n = 120). The median concentrations of 7-OH-CBD, CBD and CBD-COOH in those 221 specimens were 6.3, 1.1 and 1.2 ng/mL, respectively. ∆8-Tetrahydrocannabinol-9-carboxylic acid (∆8-THC-COOH) was identified in 76 (1.3%) specimens. Parent ∆8-THC is a minor cannabinoid in marijuana, which appears to account for the typically low ∆8-THC-COOH concentrations (median 3.4 ng/mL) in most positive specimens. However, elevated concentrations suggested the use of ∆8-THC-containing products in some cases (range 1.0-415 ng/mL). Although 93% agreement was observed between confirmatory LC-MS-MS (15 ng/mL cutoff) and immunoassay (50 ng/mL cutoff), a false-negative specimen (66 ng/mL ∆9-THC-COOH) was identified.