Justin Kahn: Cannabis Drug Test Variability — The Science and the Implications

Justin Kahn, CEO and co-founder of reepher


Legal adult-use and medical cannabis consumption is rising rapidly, but the shortcomings in cannabis drug testing have not caught up to the current reality for consumers. Cannabis can show up positive on drug test results for days, weeks, or even months after consumption, with no connection to the present level of impairment. The delay between consumption and a potentially failed drug test has profound implications for those subject to drug testing for employment, professional licensure, and investigations for driving under the influence.


The Science Behind Cannabis Drug Testing Variability

Cannabis is most commonly tested in urine or blood but can also be tested in saliva or hair. Cannabis blood tests generally focus on THC concentration, whereas urine tests look for its metabolite, THC-COOH. Test results depend on the time since consumption, amount of consumption, and individual physiological differences.

The cannabinoid delta-9 THC (or THC) and its metabolites are fat-soluble molecules. As a result, the THC consumed from cannabis is stored in fat cells and released into the bloodstream slowly over time. “SOME STUDIES” (https://pubmed.ncbi.nlm.nih.gov/24018317/) even suggest that exercise or caloric deprivation can increase the chances of a positive THC test result, even if someone has not consumed cannabis recently.

“STUDIES SHOW” (https://nij.ojp.gov/topics/articles/field-sobriety-tests-and-thc-levels-unreliable-indicators-marijuana-intoxication#note2) that ​​THC levels in biofluids are not a reliable indicator of intoxication, which suggests that unimpaired individuals could be falsely identified as impaired when the law imposes THC limits.

Failed Drug Tests from Hemp and CBD Products

For the rapidly growing numbers of hemp and CBD consumers, the question of potentially failing a drug test is a serious concern.

The passage of the “2018 FARM BILL” (https://www.congress.gov/bill/115th-congress/house-bill/2/text) legalized the sale of hemp-derived cannabinoids and products containing less than 0.3% THC in most of the United States. However, a cannabis drug test could still detect the legally allowed trace amounts of THC from full-spectrum hemp and CBD products. “EXPERTS RECOMMEND BUYERS BEWARE” (https://jamanetwork.com/journals/jama/fullarticle/2661569) because hemp and CBD products on the market vary significantly in formulation, purity, and label accuracy. Furthermore, newer delta-9 THC analogs in the grey area of the legal hemp market, such as delta-8 THC and HHC, can also come up positive on a drug test result.

The bottom line is that consumers should beware of hemp and CBD consumption before looking to pass drug tests. There is no guarantee that a product is labeled correctly or that the trace amounts of legally permissible THC in hemp and CBD products would not result in a positive test.

Implications of Cannabis Drug Test Variability

Workers and Professional License-Holders

Variability in cannabis drug testing can have profound implications for those subject to drug screenings for pre-employment or professional licensure.

Even in states with adult-use or medical cannabis programs, certain workers deemed to fill safety-sensitive roles are subject to zero-tolerance licensure regulations and employer rules. Safety-sensitive positions include CDL drivers, pilots, workers who operate heavy machinery, workers dealing with hazardous chemicals, healthcare workers, and “POLICE OFFICERS” (https://newjerseymonitor.com/briefs/state-law-allows-police-to-consume-marijuana-when-off-duty-attorney-general-says/).

The implications of cannabis drug testing variability affect individuals and entire industries alike. For example, cannabis drug testing requirements “HAVE BEEN IDENTIFIED” (https://www.businessinsider.com/marijuana-testing-leading-cause-trucker-shortage-wells-fargo-2022-2) as a leading cause of the nationwide CDL driver shortage.

Cannabis DUI and Poly-Drug Drivers

Cannabis DUIs are “ON THE RISE” (https://www.iihs.org/media/e0028841-76ee-4315-a628-32a704258980/gmJeDw/HLDI%20Research/Bulletins/hldi_bulletin_35-08.pdf) in states that have legalized adult-use cannabis consumption. Poly-drug driving, or driving under the influence of two or more drugs, is the most common reason drivers who test positive for cannabis get into fatal car accidents.

“A 2018 REPORT” (http://wtsc.wa.gov/wp-content/uploads/dlm_uploads/2018/05/Marijuana-and-Alcohol-Involvement-in-Fatal-Crashes-in-WA_FINAL.pdf) from the Washington Traffic Safety Commission found that starting in 2012, poly-drug drivers became the most prevalent type of impaired driver involved in the state’s fatal crashes. The commission reported that since 2012, the number of poly-drug drivers involved in deadly crashes had increased an average of 15% yearly. The most common poly-drug driving combination is alcohol and THC.


The precedent of alcohol testing to quan

tify the present impairment of a driver does not apply to cannabis. Breathalyzers to detect blood alcohol concentrations and legal blood alcohol limits are a quantifiable measure enforceable under state and local laws. However, the current state of cannabis testing has no similarly accurate method to quantify a driver’s impairment based on a THC drug test. There is a push from stakeholders, law enforcement, and regulatory agencies to develop more accurate methods of THC detection that correlate with present impairment. However, despite the variability in cannabis testing, a “GROWING NUMBER OF STATES” (https://www.ncsl.org/research/transportation/drugged-driving-overview.aspx) have specified THC limits for drivers. 

Final Takeaways

The growing numbers of hemp, CBD, and cannabis consumers need to be aware that THC tests can be positive long after consumption, even for months. As a result, consumers are vulnerable to severe consequences, including safety-sensitive workers, professional license-holders, and drivers. In the absence of drug detection technology to connect test results with the present level of impairment or to distinguish it from prior consumption, cannabis consumers must take precautions and stay informed.


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Carl L Rowley -Thompson Coburn LLP

Jerry Chesler – Chesler Consulting

Ian Stewart – Wilson Elser Moskowitz Edelman & Dicker LLP
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Adam Detsky – Knight Nicastro
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Peter Fendel – CMR Real Estate Network
Nate Reed – CMR Real Estate Network

Matthew Ginder – Greenspoon Marder
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William Bogot – Fox Rothschild

Valerio Romano, Attorney – VGR Law Firm, PC

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Tracy Gallegos – Associate Fox Rothschild

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Matthew G. Miller – MG Miller Intellectual Property Law LLC
Daniel T. McKillop – Scarinci Hollenbeck, LLC

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Gregory J. Ryan, Esq. Tesser, Ryan & Rochman, LLP
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