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Excretion of Delta9-Tetrahydrocannabinol in Sweat

NCJ Number
222201
Journal
Forensic Science International Volume: 174 Issue: 2-3 Dated: January 2008 Pages: 173-177
Author(s)
Marilyn A. Huestis; Karl B. Scheidweiler; Takeshi Saito; Neil Fortner; Tsadik Abraham; Richard A. Gustafson; Michael L. Smith
Date Published
January 2008
Length
5 pages
Annotation
This clinical study examined the level of THC (delta9-tetrahydrocannabinol) excreted in the sweat of 11 daily cannabis users after cessation of drug use.
Abstract
Sweat patches worn by daily cannabis users the first week of monitored abstinence had THC concentrations that averaged 3.85 ng/patch. Eight of the 11 subjects had negative second-week patches, using the cutoff concentration of 1 ng THC/patch (cutoff set by U.S. Substance Abuse Mental Health Services Administration for Federal workplace testing). One subject was still positive 4 weeks after ceasing drug use. Subjects who took THC orally up to 14.8 mg daily, either intentionally or unknowingly, did not produce a positive sweat patch at a cutoff concentration of 0.4 ng THC/patch. The advantage of sweat testing is that it is not subject to the periodic fluctuations in concentration found in sequential urine specimens, which makes identifying new drug use more difficult. Also, a single sweat patch analysis provides a summary of drug use or drug washout for the previous week. Multiple urine collections and analyses would be required to cover the same period. The sensitivity of sweat patches in detecting new drug use following cannabis smoking is not known. This requires an independent controlled smoked cannabis administration study. All study participants resided in the secure clinical research unit of the Intramural Research program, National Institute on Drug abuse, National Institutes of Health, Baltimore, MD, while participating in the clinical studies. 2 tables, 1 figure, and 27 references

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