Urinary Cannabinoid Detection Times After Controlled Oral Administration of [[Delta].Sup.9]-Tetrahydrocannabinol to Humans (Drug Monitoring and Toxicology) (Clinical Report)

[[Delta].sup.9]-Tetrahydrocannabinol (THC)6 is the major psychoactive cannabinoid in the marijuana plant Cannabis sativa. Clinical marijuana smoking studies have characterized the urinary pharmacokinetics of THC after inhalation (1-6); ingestion of cannabis has been investigated to a lesser extent (7-11). Since the mid-1990s, food products derived from cannabis plants and advertised as nutritional supplements have been available in the US; one such item is hemp seed oil. Manufacturers suggest that hemp oil is of value as a nutritional supplement because of its high concentration of the essential fatty acids [omega]-linolenic and linoleic acid. Although the hemp seed kernel does not have a substantial THC concentration, hemp oils have been found to contain a wide range of THC concentrations (12-14). The THC content of hemp oil is dependent on the effectiveness of seed cleaning and drying procedures and oil filtration processes. THC contamination originates from plant resin covering the surrounding seed hull. Ingestion of these products may produce positive urine drug tests (13, 15). This has led to questions about the validity of urine drug tests intended to deter drug use in treatment, workplace, criminal justice, and military programs. Several studies have reported that ingestion of hemp oil causes positive urine tests for cannabinoids (12, 16-18). Lehmann et al. (12) reported THC concentrations of 3-1500 [micro]g/g in 25 hemp oil samples. Six individuals ingested one or two tablespoons of hemp oil containing 1500 [micro]g/g THC (11 and 22 g of hemp oil, or ~16.5-33 mg THC). Positive urine specimens were observed with a 50 [micro]g/L cannabinoid immunoassay cutoff and a 15 [micro]g/L 11-nor-9-carboxy-[[Delta].sup.9]-tetrahydrocannabinol (THCCOOH) gas chromatography-mass spectrometry (GC/MS) cutoff for up to 6 days. Costantino et al. (18) reported that seven individuals ingesting 15 mL of hemp oil of an unknown THC concentration had positive urine drug tests by immunoassay at a cutoff of 20 [micro]g/L for up to 48 h after ingestion. GC/MS analysis of urine specimens for THCCOOH, the primary urinary metabolite of THC, identified concentrations up to 78.6 [micro]g/L. This is substantially above the federally mandated urine THCCOOH confirmation cutoff concentration of 15 [micro]g/L. It is of concern that legitimate consumption of hemp oil may be interpreted as illicit drug exposure and that hemp oil ingestion may be used to conceal illicit cannabis use.