Cannabis drug testing
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Cannabis |
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Cannabis drug testing describes various
Unlike alcohol, for which impairment can be reasonably measured using a
The concentrations obtained from such analyses can often be helpful in distinguishing active use from passive exposure, elapsed time since use, and extent or duration of use.
The
Biological timeline
Most
Testing methods
Urine testing
Marijuana use can be detected up to 3–5 days after exposure for infrequent users, 1–15 days for heavy users, and 1–30 days for chronic users and/or users with high body fat.[5][6]
Under the typical 50 ng/mL cutoff used for cannabis testing in the United States, an occasional or on-off user would be very unlikely to test positive beyond 3–4 days since the last use, and a chronic user would be unlikely to test positive much beyond 7 days.[citation needed] Using a more sensitive cutoff of 20 ng/mL (less common but still used by some labs), the most likely maximum times are 7 days and 21 days, respectively. In extraordinary circumstances of extended marijuana use, detection times of more than 30 days are possible in some individuals at the 20 ng/mL cutoff.[7]
However, every individual is different, and detection times can vary due to metabolism or other factors. It also depends on whether tetrahydrocannabinol (THC) or its metabolites are being tested for, the latter having a much longer detection time than the former. THC, the main psychoactive component of cannabis, may only be detectable in saliva and oral fluid for 2–24 hours in most cases.[8][9]
The main metabolite excreted in the urine is 11-Nor-9-carboxy-THC, also known as THC-COOH. Most cannabis drug tests yield a positive result when the concentration of THC-COOH in urine exceeds 50 ng/mL.[10] Urine testing is an immunoassay based test on the principle of competitive binding. Drugs which may be present in the urine specimen compete against their respective drug conjugate for binding sites on their specific antibody. During testing, a urine specimen migrates upward by capillary action. A drug, if present in the urine specimen below its cut-off concentration, will not saturate the binding sites of its specific antibody. The antibody will then react with the drug-protein conjugate and a visible colored line will show up in the test line region of the specific drug strip.[citation needed]
Cannabis use is included in the "10-panel urine screen", as well as the "SAMHSA-5", the five drugs tested for in standard NIDA approved drug tests.
False positives have been known to be triggered by consuming hemp-seed bars, low THC cannabis and CBD supplements, although the more detailed, more expensive gas chromatography-mass spectrometer (GCMS) test can tell the difference.[11]
In 2011, researchers at John Jay College of Criminal Justice reported that dietary zinc supplements can mask the presence of THC and other drugs in urine. Similar claims have been made in web forums on that topic.[12] However, a 2013 study conducted by researchers at the University of Utah School of Medicine refute the possibility of self-administered zinc producing false-negative urine drug tests.[13]
Common known pharmaceutical drugs which cause false positives in instant THC dip tests include:
- Proton pump inhibitors[14]
Duquenois–Levine reagent
The Duquenois–Levine test is a simple chemical color reaction test initially developed in the 1930s by Pierre Duquénois.
To administer the test, a user simply has to mix the chemicals with a particle of the suspected substance; if the chemicals turn purple, this indicates the possibility of marijuana. But the color variations can be subtle, and readings can vary by examiner.
It was adopted in the 1950s by the United Nations as the preferred test for cannabis. Such tests are often distributed in snap-to-open glass vials.
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Step 1 – addition of Duquenois reagent to dried petroleum ether extract
-
Step 2 – addition of hydrochloric acid
-
Step 3 – addition of chloroform
Azo dyes (Fast Blue B/BB)
The United Nations Office on Drugs and Crime (UNODC) found the
Beam's CBD Test
In 1911, Dr. W. Beam discovered that the tissue of hemp, which is typically low in THC but high in CBD, gives a purple color when treated with bases.[20] The test is relatively simple and inexpensive, and typically involves placing the test sample in a solution of 5% potassium hydroxide and 95% ethanol.[21] After approximately ten minutes, samples with CBD exhibit a violet/purple/pink color. The test is specific to CBD and does not react to THC.
Hair testing
Cannabis use is detectable with
Saliva testing
Cannabis is detectable by saliva testing. Just like blood testing, saliva testing detects the presence of parent drugs and not their inactive metabolites. This results in a shorter window of detection for cannabis by saliva testing.[23] Delta 9 THC is the parent compound. If a saliva sample is tested in a lab, the detection level can be as low as 0.5 ng/mL (up to 72 hours after intake).[24] Per National Institute on Drug Abuse saliva drug testing provides a reasonable alternative to other drug testing methods.[25]
Blood testing
Cannabis is detectable in the blood for approximately 12–24 hours, with heavy/frequent use detectable in the blood for up to 7 days (depending on a person's blood renewal system).[citation needed] Because they are invasive and difficult to administer, blood tests are used less frequently.[citation needed] They are typically used in investigations of accidents, injuries and DUIs.[citation needed]
Urine contains predominantly THC-COOH, while hair, oral fluid, and sweat contain primarily THC. Blood may contain both substances, with the relative amounts dependent on the recency and extent of usage.[26][27][28]
Neurological testing
Although unlikely to be used in court,
References
- PMID 19681888.
- ^ Choices, N. H. S. (2016-12-12). "How long does cannabis stay in the body after smoking? - Health questions - NHS Choices". Archived from the original on 2015-07-16. Retrieved 2017-01-09.
- ^ "Marijuana | Drug Info | Resources | Redwood Toxicology Laboratory". www.redwoodtoxicology.com. Archived from the original on 2017-01-10. Retrieved 2017-01-09.
- ^ "Weed Can Show Up in a Physical Urine Test | 24/7 Help". Los Angeles DUI Attorney.com. Retrieved 2024-03-03.
- ^ a b Erowid Cannabis (Marijuana) Vault: Drug Testing Archived 2016-09-02 at the Wayback Machine. Erowid.org (2010-02-28). Retrieved on August 7, 2011.
- ^ Marijuana Detection Time Shorter Than Previously Assumed Archived 2016-09-02 at the Wayback Machine. norml.org (2006-02-23). Retrieved on March 13, 2012.
- ^ Cary, Paul L. (April 2006). "The Marijuana Detection Window: Determining The Length Of Time Cannabinoids Will Remain Detectable In Urine Following Smoking A Critical Review Of Relevant Research And Cannabinoid Detection Guidance For Drug Courts" (PDF). National Drug Court Institute. Vol. IV, no. 2. Archived (PDF) from the original on 2016-04-22. Retrieved 2016-08-29.
- ^ "How long does marijuana stay in your system? Blood, urine, and hair". www.medicalnewstoday.com. 2019-01-29. Retrieved 2024-03-03.
- ^ "Current Knowledge on Cannabinoids in Oral Fluid".
- PMID 19007504.
- ^ Hammond, Robert L. (2019-10-11). "Three Main Differences Between CBD and THC". Archived from the original on 2020-08-14. Retrieved 2020-07-03.
- from the original on 2012-05-18. Retrieved 2016-08-29.
- (PDF) from the original on January 10, 2016. Retrieved August 29, 2016.
- ^ "Protonix Drug Interaction Sheet" (PDF). Food and Drug Administration. Pfizer. Archived (PDF) from the original on 13 March 2018. Retrieved 11 December 2017.
- ^ "Fast Blue B Salt V001655". Archived from the original on 2023-04-20. Retrieved 2017-06-08.
- ^ "Fast Blue BB Salt hemi(zinc chloride) salt F3378". Archived from the original on 2016-02-02. Retrieved 2017-06-08.
- ISBN 9780471492528.
- ^ "UNODC - Bulletin on Narcotics - 1969 Issue 4 - 005". Archived from the original on 2016-03-03. Retrieved 2017-06-08.
- ^ a b "UNODC - Bulletin on Narcotics - 1974 Issue 4 - 003". Archived from the original on 2018-04-06. Retrieved 2017-06-08.
- ISBN 9780128008270. Archivedfrom the original on 2023-04-20. Retrieved 2017-09-09.
- ^ Starks, Michael (January 1990). "Marijuana Chemistry - Genetics, Processing & Potency" (PDF). Archived from the original (PDF) on 2017-08-04. Retrieved 2019-10-28.
- ^ "Hair drug testing question and answers" (PDF). Quest Diagnostics. Archived from the original (PDF) on 2019-07-26. Retrieved 2012-10-24.
- ^ "The ABCs of Marijuana and Drug Testing". NORML.org. Archived from the original on 2012-06-14. Retrieved 2012-10-23.
- ^ "Journal of Analytical Toxicology, Vol 25, November/December 2002". Forensic Fluids Laboratory. Archived from the original on 2019-10-24. Retrieved 2015-09-15.
- ^ "Testimony on Federal Workplace Drug-Testing by Edward J. Cone, PH.D. Before the House Committee on Commerce, Subcommittee on Oversight and Investigations". Department of Health & Human Services. July 23, 1998. Archived from the original on 2001-07-22.
- PMID 20355201.
- PMID 20360126.
- PMID 17481836.
- ^ H.K. Kalant; W.H.E. Roschlau (1998). Principles of Medical Pharmacology (6th ed.). pp. 373–375.
- PMID 16162925.
Further reading
- Gilman J, Schmitt W, Potter K, et al. (2022). "Identification of ∆9-tetrahydrocannabinol (THC) impairment using functional brain imaging". PMID 34999737.