Low-level urinary cannabinoid findings after controlled administration of hemp seed products in Türkiye: Interpretive value of Δ8-/Δ9-THC-COOH patterns.

Hemp seed products—widely available and generally regarded as safe—can contain trace amounts of cannabinoids that create a complex forensic and medical interpretation challenge. This study administered controlled doses of hemp seed oil, hemp seeds, and topical hemp oil to 15 healthy volunteers in Turkey, then tracked urinary cannabinoid metabolites over 10 days using advanced testing methods. The key finding: repeated oral hemp oil consumption produced the strongest urinary signal, with cannabinoid metabolites detectable in over 93% of urine samples, reaching concentrations as high as 4.52 ng/mL—levels that could potentially trigger positive results on standard drug tests.

The research highlights a critical forensic pattern: urine from hemp seed oil consumers showed a distinctive metabolite signature, with Δ8-THC-COOH (a metabolite of delta-8 THC) significantly predominating over Δ9-THC-COOH (the primary metabolite from delta-9 THC, the main psychoactive compound). This distinct chemical fingerprint could help differentiate hemp seed consumption from actual cannabis use in forensic and medical testing scenarios. The study established a 99% upper prediction limit of 9.35 ng/mL for total THC-COOH after hemp oil exposure, providing crucial reference data for interpreting borderline or low-level positive results. Dermal application of hemp oil produced minimal detectable metabolites, while direct seed ingestion showed recurrent but weaker signals than oral oil consumption.

This research has immediate practical implications for hemp consumers, athletes, and individuals subject to drug testing. Someone using legitimate hemp seed products could conceivably test positive for cannabinoid metabolites—information critical for understanding whether a positive result indicates hemp consumption versus cannabis use. The study provides forensic toxicologists and medical professionals with the scientific framework needed to interpret low-level cannabinoid findings more accurately and fairly, while emphasizing the importance of using isomer-specific testing methods rather than standard screening that cannot distinguish between different cannabinoid sources.