Low-level urinary cannabinoid findings after controlled administration of hemp seed products in Türkiye: Interpretive...

Hemp seed products may contain trace cannabinoids that complicate the forensic interpretation of urinary cannabinoid findings. This study investigated time-dependent urinary cannabinoid findings following controlled administration of hemp seed products in Türkiye, with particular attention to the interpretive relevance of Δ8-/Δ9-derived carboxylated metabolite patterns. A validated isomer-specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was used to quantify cannabinoids and related metabolites in urine. Twenty-two hemp seed oils and twelve hemp seed products were analyzed, and 15 healthy volunteers (n = 5 per arm) underwent controlled administration of oral hemp oil, dermal hemp oil, or hemp seed ingestion, with serial urine sampling over 10 days. Repeated oral hemp oil administration produced the strongest and most sustained urinary signal, with total THC-COOH detectable in 72 of 77 samples (93.5%) and a plateau-like pattern after day 6. In this arm, the highest median total THC-COOH concentration was 3.91 ng/mL and the maximum observed concentration was 4.52 ng/mL. Hemp seed ingestion produced recurrent but lower-level findings, whereas dermal application yielded the weakest and least consistent urinary detections. In the oral oil arm, urinary findings were characterized by predominance of Δ8-THC-COOH over Δ9-THC-COOH, with Δ8-THC-COOH/Δ9-THC-COOH ratios ranging from 1.92 to 8.83. A one-sided 99% upper prediction limit (UPL₉₉) for total THC-COOH in the oral oil arm was estimated at 9.35 ng/mL. These findings provide controlled human data supporting cautious interpretation of low-level urinary cannabinoid results after hemp seed product administration and highlight the interpretive value of isomer-specific Δ8-/Δ9-THC-COOH patterns in forensic toxicology.