Marijuana (or cannabis) is now legal in many countries, changing the way we approach drug testing. Manufacturers of in vitro diagnostic (IVD) tests need to keep up with emerging trends in drug use and testing to provide the most relevant and up-to-date products.1 We need to understand why drug testing is important, and what role IVD testing plays.


Trends in Marijuana use

Just like any other drug, be it legal or illegal, marijuana must be used responsibly. Despite its legal status, many employers may still want to test their workers for marijuana use, to ensure that they’re not impaired while working.1 

More people are using marijuana than ever before

According to a recent World Drug Report from the United Nations, marijuana is the most widely-used drug worldwide.2 In 2020, more than 4% of the global population aged 15 to 64 used marijuana – a total of 209 million people.2 Prevalence of use is highest in North America, Australia, New Zealand and West Africa.2 

Marijuana use increased during the pandemic

The COVID-19 pandemic also influenced how often people used marijuana.2 For example:2 

  • In Europe, regular (weekly) marijuana users were twice as likely to increase their use of marijuana during lockdown, compared to occasional users. Interestingly, occasional users were more likely to reduce their marijuana use, or even stop completely, during lockdown.
  • In Canada in 2021, more than a quarter of people who had used marijuana reported using larger amounts and using it more often than they did before the pandemic. This was particularly prevalent in young adults (24 years and younger).

Lockdown measures were also linked to an increase in the at-home cultivation of marijuana.2

Marijuana use is on the rise in the general workforce

Looking at the workplace specifically, US-based research shows that more employees and applicants are testing positive for marijuana use since its legalization.3 In 2022, positivity rates for marijuana in the general US workforce increased by 8.3% to the highest-ever positivity rate reported in the Drug Testing Index (DTI).3


Why is Marijuana Testing (and Drug Testing in General) Important?

Marijuana, workplace injuries and road accidents

Increased use of marijuana has unfortunately led to more marijuana-related issues in the workplace.4 Research shows that those who use marijuana before or at work have double the risk of a workplace injury compared to people who don’t use it.4

Higher use of marijuana has also been linked to higher rates of traffic accidents and drug-related fatalities.5 A US-based study shows that the percentage of car crash deaths in the country involving cannabis and alcohol doubled between 2000 and 2018.5 

Marijuana causes impairment, which leads to accidents

The acute effects of marijuana use include impaired cognitive development and impaired psychomotor performance.6 Learning, recall, attention and coordination are all affected.6 This makes performing certain tasks (such as driving) more difficult and/or dangerous.

How long does marijuana impairment last? 

It’s not known exactly how long marijuana impairment can last. When smoking or vaping, plasma tetrahydrocannabinol (THC) concentrations peak between 3 and 10 minutes after the final inhalation, and then fall rapidly within 20 to 30 minutes as the drug is absorbed.7 Blood levels of THC then reach a stable plateau which lasts for several hours.7 

Impairment only declines slowly 5 to 6 hours after a dose.7 This means that issues like slow reaction times could last for several hours after smoking, so the affected person shouldn’t be driving or doing any hazardous or precision-based work during this time.

According to the World Health Organization, marijuana can impair motor function for as long as 24 hours.6 

“Human performance on complex machinery can be impaired for as long as 24 hours after smoking as little as 20 mg of THC in cannabis; there is an increased risk of motor vehicle accidents among persons who drive when intoxicated by cannabis.”
- World Health Organization6  

Marijuana use can also cause long-term issues, like dependence, respiratory problems and impairment of cognitive function.6

“As more people use cannabis, the likelihood of their suffering medical and health consequences also increases.”
- United Nations Office of Drugs and Crime2

Why drug testing is important 

Drug testing in an employment setting helps to promote a safer workplace.8 It ensures compliance with legal or federal regulations, and reduces employee healthcare costs.8  Being held accountable for marijuana use through regular testing in the workplace may help promote responsible use and discourage abuse of the drug. 

Testing is therefore likely to play a role in work performance and employee safety.

In a clinical setting, drug testing is important because it gives an accurate indication of a patient’s drug use.9 This information will influence the treatment and monitoring the patient receives.

A note on the global opioid crisis

While marijuana use and abuse is on the rise, opioid abuse remains at epidemic levels.10 An estimated 16 million people (including 3 million in the US alone) have had or currently have opioid use disorder (OUD).10 More than 500,000 people in the US are dependent on heroin.10 

This further highlights the importance of drug testing, which can offer insights into the prevalence of drug use and the issues that come with it.

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IVD Testing for Marijuana and Other Drugs

An increased use in marijuana in the workplace means an increased use for drug screening.1 

IVD testing uses tissue and fluid samples to detect the presence of a drug.1 Medix Biochemica provides reagents for use in many different types of drug detection tests, including those using urine, saliva, blood and even hair samples.1 

How accurately can IVD tests show the timeframe in which marijuana was used? 

This depends on whether the test is measuring the ‘parent drug’ (the non-metabolized version of the drug) or the metabolites of that drug:1

  • Marijuana metabolites are found in urine and may be detectable for up to 30 days after use
  • The ‘parent drug’, delta-9 tetrahydrocannabinol (THC), is found predominantly in the saliva and is usually only detectable for up to 24 hours after use

Because testing for the parent drug detects recent marijuana use, it’s a more reliable indication that someone might be impaired.1 This is why employers will typically opt for saliva-based marijuana testing when wanting to ensure that their employees aren’t impaired while doing hazardous work.1

Note: All drug-testing immunoassays are screening tests. Any positive result would need to be double-checked and confirmed with a more sensitive and precise assay, usually by mass spectrometry.1

How does Medix Biochemica help clients to develop accurate drug tests?

Medix Biochemica provides the antibodies and antigens (reagents) that are used to build accurate screening tests.1 These include reagents for detecting either parent drugs via saliva testing, or metabolites via urine testing.1 

The two most important factors in IVD testing for marijuana and other drugs of abuse are:1

  • To meet the cut-offs that are established
  • To have little to no cross-reactivity with other substances in the sample

Medix Biochemica provides high-quality reagents that produce reliable results and do not cross-react with other substances.1 Some of these reagents are designed to specifically detect the presence of a parent drug, while others detect metabolites.

We also offer products for opioid testing, which can differentiate between prescription opioids and illegal drugs like heroin.1

For example, Medix Biochemica offers a reagent for specifically detecting the heroin metabolite 6-monoacetylmorphine (6-MAM), which is found in urine.1 This is more effective than testing for a metabolite like morphine, which isn’t specific to heroin and may show up in a sample due to legitimate prescription drug use.1

Drug use – and therefore drug testing – is always evolving, with new designer drugs coming onto the market regularly.1 At Medix Biochemica, we stay abreast of the latest developments in drug testing, to offer reliable testing reagents and biospecimens that meet our clients’ evolving needs.1

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  1. Expert opinion. Interview with Amy Moore, Product Manager at Medix Biochemica. May 18, 2023.  
  2. United Nations Office on Drugs and Crime. World Drug Report Booklet 3: Drug market trends: cannabis, opioids. 2022.
  3. Quest Diagnostics. Drug testing index™ and industry insights. 2022. 
  4. Cannabis use linked to higher injury risk, but only among those who use at or before work. Institute for Work & Health. Accessed June 27, 2023.
  5. Lira MC, Heeren TC, Buczek M, et al. Trends in cannabis involvement and risk of alcohol involvement in motor vehicle crash fatalities in the United States, 2000‒2018. Am J Public Health. 2021;111(11):1976-1985. doi:10.2105/AJPH.2021.306466.  
  6. Cannabis. World Health Organization. Accessed June 27, 2023.  
  7. Pearlson GD, Stevens MC, D’Souza DC. Cannabis and driving. Front Psychiatry. 2021;12:689444. doi:10.3389/fpsyt.2021.689444.
  8. Benefits of drug testing. DISA. Accessed June 27, 2023.
  9. McNeil SE, Chen RJ, Cogburn M. Drug testing. In: StatPearls. StatPearls Publishing; 2023. 
  10. Azadfard M, Huecker MR, Leaming JM. Opioid addiction. In: StatPearls. StatPearls Publishing; 2023.

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