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Drug Testing


A drug test is a technical analysis of a biological specimen. An example would be urine, hair, blood, sweat, or oral fluid / saliva. Often used to determine the presence or absence of specified parent drugs or their metabolites. Major uses of drug testing are to detect the presence of performance enhancing steroids in sport or for drugs prohibited by laws.

Studies show driving can actually improve while using cannabis, however it is not advised to do so especially combined with alcohol.
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Science and Research

2012 - Study ~ Cannabis - from cultivar to chemovar.

2012 - Study ~ Unexpected interference of baby wash products with a cannabinoid (THC) immunoassay.

2012 - Study ~ Detecting impairment associated with cannabis with and without alcohol on the Standardized Field Sobriety Tests.

2012 - Study ~ A placebo-controlled study to assess Standardized Field Sobriety Tests performance during alcohol and cannabis intoxication in heavy cannabis users and accuracy of point of collection testing devices for detecting THC in oral fluid.

2012 - Study ~ Investigation of drugs of abuse and relevant metabolites in Dutch sewage water by liquid chromatography coupled to high resolution mass spectrometry.

2012 - Study ~ Are cannabis prevalence estimates comparable across countries and regions? A cross-cultural validation using search engine query data.

2012 - News ~ Strange Reason for Baby's Positive Pot Test Found.

2011 - Study ~ The current status of community drug testing via the analysis of drugs and drug metabolites in sewage.

2011 - Study ~ Cannabinoids in postmortem toxicology.

2011 - Study ~ Postmortem redistribution of Δ9-tetrahydrocannabinol (THC), 11-hydroxy-THC (11-OH-THC), and 11-nor-9-carboxy-THC (THCCOOH).

2011 - Study ~ A preliminary investigation on the distribution of cannabinoids in man.

2011 - Study ~ Use of high-resolution accurate mass spectrometry to detect reported and previously unreported cannabinomimetics in "herbal high" products.

2011 - Study ~ Simultaneous determination of delta-9-tetrahydrocannabinol cannabidiol and cannabinol in edible oil using ultra performance liquid chromatography-tandem mass spectrometry.

2011 - Study ~ Immunochemical approach using monoclonal antibody against Δ(9)-tetrahydrocannabinolic acid (THCA) to discern cannabis plants and to investigate new drug candidates.

2011 - Study ~ Metabolic acidosis, hypoglycemia, and severe myalgias: an attempt to mask urine drug screen results.

2011 - News ~ New tests for 'legal marijuana,' 'bath salts' and other emerging designer drugs.

2011 - News ~ What Causes False Positives in Marijuana Drug Testing?

2010 - Study ~ Testing for cannabis in the work-place: a review of the evidence.

2010 - News ~ What Drugs Appear on a Drug Test?

2010 - News ~ Just Say ‘No’ to Drug Tests -Then Bargain.

2010 - News ~ Has the Most Common Marijuana Test Resulted in Tens of Thousands of Wrongful Convictions?

2010 - News ~ Drugs That Test Positive for THC.

2010 - News ~ APA: Drug Test Results Often Flawed.

2010 - News ~ How To Cleanse the Body From THC.

2009 - Study - Reintoxication: the release of fat-stored Delta-tetrahydrocannabinol   (THC) into blood is enhanced by food deprivation or ACTH exposure.

2009 - Study - Passive inhalation of cannabis smoke--is it detectable?

2008 - Study ~ Biomarkers for the effects of cannabis and THC in healthy volunteers.

2008 - News - Drug-Test Cheats Try New Tricks on Labs

2007 - Study ~ The Effects of Adulterants and Selected Ingested Compounds on Drugs-of-Abuse Testing in Urine.

2007 - Study ~ Human Cannabinoid Pharmacokinetics.

2007 - Study ~ Roadside sobriety tests and attitudes toward a regulated cannabis market.

2007 - Study ~ Urine drug test interpretation: what do physicians know?

2007 - Study ~ Toxicity From the Use of Niacin to Beat Urine Drug Screening.

2007 - News ~ Misusing Vitamin To Foil Drug Test May Be Toxic; Plus, It Doesn't Work.

2006 - Study ~ Review of biologic matrices (urine, blood, hair) as indicators of recent or ongoing cannabis use.

2006 - Study ~ Drugs of Abuse: Analyses and Ingested Agents That Can Induce Interference or Cross-Reactivity.

2004 - Study ~ Drug testing in the workplace.

2004 - Study ~ Passive Inhalation of Cannabis Smoke.

2004 - Study ~ A Review of Internet-Based Home Drug-Testing Products for Parents.

2003 - Study -  Practical Challenges to Positive Drug Tests for Marijuana.

2002 - Study ~ Effects of Stealth adulterant on immunoassay testing for drugs of abuse.

2002 - Study ~ A procedure for the detection of Stealth adulterant in urine samples.

2002 - Study ~ Effects of oxidizing adulterants on detection of 11-nor-delta9-THC-9-carboxylic acid in urine.

2002 - Study ~ Toxicological Screening for Drugs of Abuse in Samples Adulterated with Household Chemicals.

2000 - Study ~ Effects of pyridinium chlorochromate adulterant (urine luck) on testing for drugs of abuse and a method for quantitative detection of chromium (VI) in urine.

2000 - Study ~ Consumption and quantitation of delta9-tetrahydrocannabinol in commercially available hemp seed oil products.

2000 - Study ~ GC-MS analysis of the total delta9-THC content of both drug- and fiber-type cannabis seeds.

1996 - Study ~ Passive inhalation of cannabis smoke: a novel defence strategy?

1989 - Study ~ Legal and ethical aspects of drug testing.

1989 - Study ~ Interference of Common Household Chemicals in Immunoassay Methods for Drugs of Abuse.

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Reintoxication: the release of fat-stored Delta-tetrahydrocannabinol (THC) into blood is enhanced by food deprivation or ACTH exposure

Gunasekaran N, Long LE, Dawson BL, Hansen GH, Richardson DP, Li KM, Arnold JC, McGregor IS

 Br J Pharmacol 2009 Nov; 158(5):1330-7.


Delta(9)-tetrahydrocannabinol (THC), the main psychoactive constituent of cannabis, accumulates in adipose tissue where it is stored for long periods of time. Here we investigated whether conditions that promote lipolysis can liberate THC from adipocytes to yield increased blood levels of THC.


In vitro studies involved freshly isolated rat adipocytes that were incubated with THC before exposure to the lipolytic agent adrenocorticotrophic hormone (ACTH). A complementary in vivo approach examined the effects of both food deprivation and ACTH on blood levels of THC in rats that had been repeatedly injected with THC (10 for 10 consecutive days. Lipolysis promoted by ACTH or food deprivation was indexed by measurement of glycerol levels.


ACTH increased THC levels in the medium of THC-pretreated adipocytes in vitro. ACTH also enhanced THC release from adipocytes in vitro when taken from rats repeatedly pretreated with THC in vivo. Finally, in vivo ACTH exposure and 24 h food deprivation both enhanced the levels of THC and its metabolite, (-)-11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (THC-COOH) in the blood of rats that had been pre-exposed to repeated THC injections.


The present study shows that lipolysis enhances the release of THC from fat stores back into blood. This suggests the likelihood of 'reintoxication' whereby food deprivation or stress may raise blood THC levels in animals chronically exposed to the drug. Further research will need to confirm whether this can lead to functional effects, such as impaired cognitive function or 'flashbacks'.


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Practical Challenges to Positive Drug Tests for Marijuana

(Clinical Chemistry. 2003;49:1037-1038.)
© 2003 American Association for Clinical Chemistry, Inc.


Practical Challenges to Positive Drug Tests for Marijuana

Mahmoud A. ElSohly

ElSohly Laboratories, Incorporated, 5 Industrial Park Dr., Oxford, MS 38655 and National Center for Natural Products Research, The University of Mississippi, University, MS 38677

With the advent of drug testing in the workplace and the consequences of a positive drug test, several issues have arisen in defending or explaining a positive result for a given drug of abuse. Marijuana is the illicit drug with the highest percentage of positives in workplace drug testing. Consequently, marijuana was the first such drug for which excuses were provided to explain the positive test result.

Passive inhalation was the first defense offered. This prompted several studies to ascertain whether passive inhalation of marijuana smoke could produce a positive drug test.

The majority of these studies showed that although passive inhalation of marijuana smoke under certain circumstances could produce detectable concentrations of {Delta}-9-tetrahydrocannabinol (THC) metabolite in urine, those concentrations were not above the cutoffs used under the federal workplace drug testing guidelines (50 µg/L for screening and 15 µg/L for confirmation).

One study, however, showed that concentrations above these cutoffs could be attained when the exposure conditions were very severe and, hence, unrealistic. Today, passive inhalation is not nearly the issue that it was at the beginning of drug testing in the workplace.

The second issue was passive ingestion. Unknowing ingestion of marijuana tea, brownies prepared with marijuana, or the like was the line of defense that followed passive inhalation. Although studies were carried out to investigate this issue, there was no question that if someone orally ingested cooked marijuana, urinary excretion of {Delta}-9-THC metabolite would correlate with the amount ingested.

The issue was whether the concentrations found in the urine at a specific time after ingestion could be explained in the absence of a detectable biological activity at the time of ingestion. This issue still has no definitive resolution in light of the fact that individuals have explained that there was alcohol consumed with the meals, which could mask the effects of marijuana.

Over the last few years, hemp-seed oil and hemp-seed products have come to the forefront of defense issues in marijuana cases. Hemp seeds and hemp-seed oil are products that have been legal, that are being ingested by individuals for health reasons (hemp-seed oil is known to contain high concentrations of unsaturated fatty acids), and that were thought, until recently, to contain no THC.

The fact that these products do contain THC presents a challenge in prosecuting positive marijuana-use cases. The seriousness of the issue was demonstrated by studies in which an individual or a few individuals ingested a hemp-seed product (hemp-seed oil or hemp-seed-oil capsules), and the THC metabolite was measured in their urine.

Hemp-seed oil is presumed to be prepared from the fiber-type cannabis, which contains very low concentrations of THC. If, however, the oil is prepared from drug-type seeds with a high THC content, the oil will contain higher concentrations of THC. Moreover, the presence of THC in the cannabis seeds is attributable to adherence of the resin to the outside of the seeds as a result of physical contact with the plant material during processing.

As the oil is pressed out of the seeds, it extracts THC from the exterior seed coat. Plant particles present with the seeds will also be extracted by the oil, increasing the THC content of the oil. Therefore, the THC content of the oil is a function of the type of seeds (fiber- or drug-type) and the presence of leaf debris.

Analysis of a wide variety of hemp-seed products and hemp-seed oil has revealed a broad range of THC content (anywhere from a few mg/L to >200 mg/L). This variation in the THC content coupled with variations in the use patterns of these products among individuals (from the equivalent of 1 mL of oil in the form of soft gelatin capsules to ≥1 tablespoons of oil) make it difficult to offer generalized statements about whether the use of hemp-seed products could produce a positive urine drug test.

Recently, the hemp-seed industry has made an effort to lower the THC content of the seeds by including a wash step before pressing or by shelling the seeds. Shelled seeds were found to contain very little THC (in the range of 2 µg/g).

A study was therefore initiated by Leson et al. to investigate the possibility of a positive urine drug test as a result of daily ingestion of various amounts of these "new" preparations, with total daily doses of THC ranging from 0.09 to 0.6 mg (equivalent to 45–300 g of hulled hemp seeds containing 2 µg/g THC or 19–120 mL of hemp-seed oil at 5 mg/L THC) in the form of blends of hemp-seed oil and canola oil to achieve the required dose of THC in a total of 15 mL of oil. The study design was based on the premise that if one ingested hemp-seed oil on a regular basis (daily), analysis of the urine after several days of ingestion would reveal detectable urine concentrations at times after steady-state conditions were achieved.

To limit the number of samples to be analyzed and still obtain meaningful data, urine samples were collected 4–8 h after dosing on days 9 and 10 and after 1 and 3 days of dose termination. With the exception of one urine specimen from the 0.6 mg daily dosing, all urine specimens failed to screen positive for cannabinoids at 50 µg/L.

Furthermore, the highest gas chromatography–mass spectrometry (GC/MS) confirmation concentration in any of the urine samples was 5.2 µg/L, far below the 15 µg/L GC/MS confirmation cutoff used in regulated drug testing. The shortcoming of this study was the limited number of urine collections, although the 4–8 h delay was designed to achieve collection at times approximating the cmax.

The latest study to address the impact of the use of hemp-seed oil on urine drug tests is reported in this issue. The study was designed to address the pharmacokinetics and pharmacodynamics of oral THC in the form of hemp-seed oil or prescription Marinol capsules. The study design included dosing three times daily for 5 consecutive days and collection of all urine samples voided throughout the study.

This design and the analysis of all samples assured that no positive urine would go undetected, a significant difference from the previous study by Leson et al. . Although the data for the low doses of THC in this study (0.39 and 0.47 mg total dose of THC) were generally similar to those reported by Leson et al. , a few samples exceeded the federally mandated screening cutoff of 50 µg/L and the 15 µg/L GC/MS confirmation cutoff. Intersubject variability coupled with the fact that all urine specimens were collected in the present study could explain the higher incidence of positive urines in this new study.

The conclusion, however, was that it is possible, but unlikely, for a urine specimen to test positive at the federally mandated cannabinoid cutoffs if the manufacturers’ dosing recommendations for the ingestion of low-THC-concentration hemp oils are followed.

Therefore, the interpretation of positive urine tests for marijuana should be made with care and on a case-by-case basis. Claims of ingestion of food stuffs containing hemp-seed oil should be verified by analysis of the products ingested to determine the THC dose allegedly ingested and to determine whether the THC metabolite concentration in the urine is consistent with the dose ingested.



  1. Perez-Reyes M, Di Guiseppi S, Mason AP, Davis KH. Passive inhalation of marihuana smoke and urinary excretion of cannabinoids. Clin Pharmacol Ther 1983;34:36-41.[Web of Science][Medline]
  2. Mason AP, Perez-Reyes MJ, McBay AJ. Cannabinoid concentrations in plasma after passive inhalation of marijuana smoke. J Anal Toxicol 1983;7:172-174.[Medline]
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  4. Mule SJ, Lomax P, Gross SJ. Active and realistic passive marijuana exposure tested by three immunoassays and GC/MS in urine. J Anal Toxicol 1988;12:113-116.[Web of Science][Medline]
  5. Cone EJ, Johnson RE, Darwin WD, Yousefnejad D, Mell LD, Paul BD, et al. Passive inhalation of marijuana smoke: urinalysis and room air levels of delta-9-tetrahydrocannabinol. J Anal Toxicol 1987;11:89-96.[Web of Science][Medline]
  6. Law B, Mason PA, Moffat AC, Gleadle RI, King LJ. Forensic aspects of the metabolism and excretion of cannabinoids following oral ingestion of cannabis resin. J Pharm Pharmacol 1984;36:289-294.[Web of Science][Medline] [Order article via Infotrieve]
  7. Cone EJ, Johnson RE, Paul BD, Mell LD, Mitchell J. Marijuana-laced brownies: behavioral effects, physiological effects, and urinalysis in humans following ingestion. J Anal Toxicol 1988;12:169-175.[Web of Science][Medline
  8. Fortner N, Fogerson R, Lindman D, Iversen T, Armbruster D. Marijuana-positive urine test results from consumption of hemp seeds in food products. J Anal Toxicol 1997;21:476-481.[Web of Science][Medline]
  9. Lehman T, Sager F, Brenneisen R. Excretion of cannabinoids in urine after ingestion of cannabis seed oil. J Anal Toxicol 1997;21:373-375.[Web of Science][Medline]
  10. Constantine A, Schwartz RH, Kaplan P. Hemp oil ingestion causes positive urine tests for {Delta}9-tetrahydrocannabinol carboxylic acid. J Anal Toxicol 1997;21:482-485.[Web of Science][Medline]
  11. Bosy TZ, Cole KA. Consumption and quantitation of {Delta}9-tetrahydrocannabinol in commercially available hemp seed oils and products. J Anal Toxicol 2000;24:562-566.[Web of Science][Medline]
  12. Ross SA, Mehmedic Z, Murphy TP, ElSohly MA. GC/MS analysis of the total delta-9-THC content of both drug- and fiber-type cannabis seeds. J Anal Toxicol 2000;24:715-717.[Medline]
  13. Leson G, Pless P, Grotenhermen F, Kalant H, ElSohly MA. Evaluating the impact of hemp food consumption on workplace drug tests. J Anal Toxicol 2001;25:691-698.[Web of Science][Medline] [Order article via Infotrieve]
  14. Gustafson RA, Levine B, Stout PR, Klette KL, George MP, Moolchan ET, et al. Urinary cannabinoid detection times after controlled oral administration of {Delta}9-tetrahydrocannabinol to humans. Clin Chem 2003;49:1114-1124.[Abstract/Free Full Text]

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Toxicity From the Use of Niacin to Beat Urine Drug Screening

Annals of Emergency Medicine
Volume 50, Issue 5 , Pages 587-590, November 2007

Presented at the 8th Annual Clinical Pathological Case Presentation Competition, 2006 North American Congress of Clinical Toxicology (NACCT) meeting, October 2006, San Francisco, CA.

  • Manoj K. Mittal, MD, MRCP


    • Division of Emergency Medicine, The Children’s Hospital of Philadelphia, Philadelphia, PA
    • Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, PA
    • Address for correspondence: Manoj K. Mittal, MD, MRCP, Division of Emergency Medicine, The Children’s Hospital of Philadelphia, 34th Street and Civic Center Boulevard, Philadelphia, PA 19104-4399; 215-590-1944, fax 215-590-4454
    email address
  • ,
  • Todd Florin, MD


    • Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, PA
  • ,
  • Jeanmarie Perrone, MD


    • Department of Emergency Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA
  • ,
  • João H. Delgado, MD


    • Divisions of Emergency Medicine and Medical Toxicology, Hartford Hospital, Hartford, CT.
  • ,
  • Kevin C. Osterhoudt, MD, MSCE


    • Division of Emergency Medicine, The Children’s Hospital of Philadelphia, Philadelphia, PA
    • Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, PA

Received 28 October 2006; received in revised form 29 November 2006 and 3 January 2007; accepted 19 January 2007. published online 06 April 2007.

Niacin (vitamin B3) is promoted for rapidly clearing the body of drugs of abuse, such as cocaine and cannabis, and is alleged to interfere with urine drug screening. We present 4 cases of such novel use associated with significant adverse effects.

Two cases had isolated skin manifestations, whereas the other 2 presented with life-threatening manifestations, including nausea, vomiting, dizziness, hepatotoxicity, metabolic acidosis, and hypoglycemia evolving into hyperglycemia. One patient also had profound neutrophilia and QTC-interval prolongation.

All patients improved after cessation of the drug use and supportive treatment. Health care providers should be aware of these potential adverse effects of niacin and of the misguided use of this vitamin by patients seeking to interfere with urine drug screening.

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Drug-Test Cheats Try New Tricks on Labs

Experts Say Internet and Household Products Bring New
Challenges to Drug Testing
By Todd Zwillich
WebMD Health News
Reviewed by Louise Chang, MD

July 28, 2008 -- Vinegar. Lemon juice. Drain-cleaning products. At least one of these items is probably in your kitchen. And any of them can be used to beat a drug test.

For about 20 years, people have been using a long list of very ordinary household items to confuse prospective employers and drug labs hoping to catch them in the act of using or abusing illegal drugs.

Add to the list laundry detergent, baking soda, and ordinary salt.

"Does it work? Yes, it does," says Amitava Dasgupta, PhD, a professor of pathology and drug testing expert from the University of Texas-Houston Medical Center. "It's a cat and mouse game."

Employer drug testing became popular in the late 1980s after President Ronald Reagan instituted drug testing as a requirement for federal jobs. Lots of private companies followed suit, and today thousands run drug tests on people applying for jobs.

Many schools also conduct drug tests on students trying to join sports teams, or, more controversially, sometimes conduct tests on a random basis.

Many household items change urine's pH, or acidity, when they're added to it; most of the time that renders a sample useless for testing. But these are not the cheating methods that worry testers like Dasgupta.

That's because labs can easily tell when urine has been adulterated with household items. Usually they just disqualify the applicant without even bothering to test for specific drugs.

Online Test-Cheating Industry

That's what happens with most of the so-called "detoxifying" drinks that can be found online. Most of the drinks are simply loaded with caffeine and come with directions to drink lots and lots of water. That dilutes the urine, which can sully a drug test.

But testers are prepared for dilution, Dasgupta says. Any sample below a certain concentration is automatically rejected, regardless of whether it has evidence of illegal drugs in it.

"There is no magic formulation which can take drugs out of your body," Dasgupta says.

Chris Faught, who heads chemical testing at the University of Arkansas for Medical Sciences, says his lab routinely sees dilution as a strategy to fool drug tests in the emergency room. "We get results that are simply suppressed so there's obviously an interfering substance. The old classic way is to drink lots and lots of water," he tells WebMD.

But the gigantic test-cheating industry, found mostly online, has given toxicologists like Dasgupta new problems to contend with. One popular formulation is called pyridinium chlorochromate (PCC). It destroys drug molecules in urine, potentially fooling drug tests.

But there's a catch: the simple addition of some hydrogen peroxide will turn a PCC-containing urine sample dark brown.

Testing for Marijuana Use

"The bottom line is toxicologists are smarter than drug abusers," Dasgupta told reporters at a meeting of the American Association for Clinical Chemistry in Washington. "If try to cheat on a drug test, we will catch you."

That's usually true. But even Dasgupta concedes there are some holes in his drug-testing net. He says parents should be on the lookout for over-the-counter eyedrops. A full vial of the easy-to-buy product can successfully mask THC -- marijuana's active ingredient -- if it's added to a urine sample.

This cheating method doesn't work for heavy marijuana users. But for "borderline" tests, some eyedrops can envelop THC molecules, effectively hiding them from chemical detection, adds Dasgupta.

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