Understanding Drug Screening: A Positive Step Towards a Safer Workplace

Construction Site with Workers


Employer drug screening is a critical process that helps ensure a safe workplace. This article will provide an overview of drug screening, its purpose, what a positive drug test means, ways to interpret the results, and a real-life example that shows the complexity for both the employer and employee.

Drug Screening Overview

What is Drug Screening?

The Purpose of Drug Screening

  • Employer drug screening is the systematic process of testing individuals for the presence of drugs or drug metabolites. These tests detect metabolites by collecting urine, blood, hair follicle, and saliva samples.
  • Employers commonly use it to evaluate employees for drug use before hiring and during work hours to ensure a safe workplace. 
  • Drug tests are objective assessments without human bias that detect the presence of the drug.

  • The primary objective of drug screening is to deter drug use in the workplace, ensuring a safer environment for all employees. The following drug testing scenarios are the most common in the U.S.
  1. Pre-employment
  2. Random
  3. Upon-Suspicion
  4. Post-Accident

  • Employers want to protect employees from individuals who engage in substance use–even if they are legal–during working hours that could impact their work performance, productivity, and safety.
  • Drug screens can be administered onsite to provide rapid results, typically within 20 minutes, or sent to a lab for testing. Lab testing may take 2-5 days to get the results back. For more information, please see the pros and cons of drug testing.   
  • Onsite drug screening enables employers to make informed decisions and implement steps to warn,  remove, train, educate, or consider other actions to ensure workplace safety. 

Understanding Your Drug Test Results

How does Drug Testing Work?


A drug test is a relatively simple process but often takes days to complete.  Typically, testing involves collecting an individual’s urine, saliva, blood, or hair samples. Although collecting the sample takes only a few minutes, the entire process can take 2-5 days to complete. This unproductive downtime is anxiety-provoking for employees and costly for employers. To learn more about the pros and cons of each test and which test is best for your company, please read the article Compare Drug Testing Methods – Pros and Cons for Each Drug Test


“>Drug tests can test for one substance or can be a panel that tests for multiple substances, such as opioids, marijuana, cocaine, amphetamines, and benzodiazepines.  Employers should determine what their most significant issue is, and based on the data from Quest Diagnostics on Positive rates, which reported over 16 million drug tests from 2018 to 2022, cannabis was the most common drug tested and has the highest positivity rates. (6)


Cannabis metabolism is complex and beyond the scope of this article, but inactive metabolites are stored and persist in fat tissue for over 30 days. For cannabis consumption, this article by the addiction centers provides an excellent overview.  


After taking a drug test, the sample is analyzed, and a report shows the presence or absence of drugs or their metabolites in this particular sample.


Employers obtain the drug test results from the testing laboratory or the onsite testing device. 

Lab Testing Image

What Does the Interpretation of Drug Test Results Mean?

A Negative Drug Test
A Positive Drug Test

A negative drug test detects no active drug or derived metabolites. 

A positive or non-negative drug test detects the active drug or derived metabolites.

  1. A saliva test can detect the parent drug Delta-9 THC, confirming that marijuana was consumed in the last 30 minutes to 10 hours, otherwise known in the industry as recent use.  
  2. A urine tests detect inactive metabolites such as TCH-COOH, which shows that cannabis was consumed but can not distinguish past use from recent use. (2,3,4,5)

What Does the Interpretation of Drug Test Results Not Mean?

  • A positive drug test does not indicate current impairment or intoxication. Again, the positive results confirm the presence of drugs. 
  • Using newer marijuana drug screens such as an oral fluid or saliva test enables employers to perform the drug screen on-site, providing rapid results.  Many recent publications, including the one by Robertson and his colleagues in Canada in 2022, show that oral fluid is a reliable indicator for THC consumption, showing recent use detection and often more reliable than urine tests. (2,3,4,5) 


Cannabis laws are changing rapidly, especially over the last five years.  For example, effective Jan 1st, 2024,  California bill AB 2188 prohibits employers from hiring, firing, or taking employment action for test results that detect the non-psychoactive cannabis metabolites.  Therefore, employers must ensure their HR policies are up-to-date and comply with state and local laws. For more information on HR policies and best practices, please see the Employer Drug Testing – Policies and Procedures.

As mentioned above, there are many benefits from these marijuana drug screens. Still, it is often best practice for employers to conduct a confirmatory 2nd test with a nearby lab if a rapid test is positive or sometimes referred to as non-negative. To learn more on why employers are moving towards oral fluid testing, please click to read the article Employers are Using Recent Use Cannabis Testing: Balancing a Safe & Fair Workplace.  

Although a confirmatory test incurs more costs and may seem repetitive, these confirmatory lab tests use different machines, and it is often best to verify the positive drug test result. It is best to assume these onsite test results are often not legally defensible, but it is essential to confirm with your legal teams or employment attorney.

Positive Drug Test with Prescription

  • In some cases, an individual may test positive for a drug even if they have a valid prescription for it.
  • Employers should have policies and procedures to handle such situations, including requiring individuals to provide proof of their prescription.

The Impact of Positive Drug Tests at Work

Considerations of Employer - Sponsored Workplace Drug Testing

  • A positive drug test at work can have severe consequences for an individual, including forced time off, job loss, reduced opportunities, and damage to their professional reputation.
  • Employers may have specific policies and procedures for dealing with positive drug tests, such as offering rehabilitation or training programs or imposing disciplinary actions.
  • Employers must know the details of the test you are using, such as the detection window and sensitivity, to ensure you objectively measure and interpret the results.  

For more information on employer drug testing with an example, 
please see this article, Navigating the Complex Landscape 
of Workplace Drug and Alcohol Testing: A Guide for Employers.

Woman who nervously waits for her drug test

Real-Life Example Drug Testing - Employee Perspective

Below is an example of a day in the life of an employee taking a drug test, illustrating how drug testing works and its consequences. 

Recently, a 42-year-old woman was interviewed and got an acceptance letter from a large, privately held company that operates in multiple states as a front-line manufacturing worker. Before her first day, human resources welcomed her warmly but told her she needed to get tested for a routine drug test. After hearing the news, she wasn’t surprised because she heard from a peer and on the glass door that this was standard practice. However, anxiety mounted as she suddenly remembered that about a week ago, the host offered her edibles and liquid tinctures to spice up her wine.  She popped one gummy and was not sure what the dosage was and added a tincture of THC to her drink.  After about an hour, she felt happy and lighter on her feet.  Since she was unsure what the dosage was, she was uncertain how long it would last and decided to sleep it off at her friend’s house, leaving her car parked in her friend’s driveway.  

Suddenly, her mind went down a spiral, looking up frantically on how to beat a drug, triggering her to buy fake urine from a stranger, consider sneaking a clean urine sample in her pants to the testing site, and ponder alternatives to pass this drug screening.  She was not acting deceitfully but scared and did not want to lose this opportunity.  Ultimately, she was qualified, could do the job on day 1 with her vast experience, and was excited about this transition. 

This extra step caused so much anxiety and stress.  In the end, although she considered it, she decided to wait two more weeks to take the test and delayed her start date, costing her two weeks of pay.  The employer agreed, and she took the test on Wednesday.  She spent the next two days worrying if she passed the test, and then on Friday, the test results showed that she had passed and confirmed her start date with HR and her supervisor.   

Ultimately, what was supposed to be a happy situation, a new job, turned into a stressful 3-4 weeks. She regrets going to that party and wishes not to smoke marijuana because it was not worth the stress.  Instead, she missed 2-3 weeks of work or could have taken that time to recharge and relax before starting a new job. Lastly, this whole scenario could be very different if the employer had a better testing method that tests for recent use and not past, such as employing a saliva testing method for recent use. If this were the case, the employee would be less stressed and confident to test earlier and not force the employer to wait another 2-3 weeks to test, allowing the employee to be onboard quicker.  


Understanding drug screening is essential for maintaining a safe workplace environment. It helps employers identify individuals engaging in substance abuse and take appropriate actions. Employers can ensure a drug-free workplace by implementing a comprehensive drug screening program, promoting employee safety, productivity, and overall well-being.


  1. Dan Wagener, M.A. How Long Does Marijuana (Weed) Stay in Your System? Sep 13, 2022
  2. Musshoff, F. & Madea, B. Review of Biologic Matrices (Urine, Blood, Hair) as Indicators of Recent or Ongoing Cannabis Use. Ther. Drug Monit. 28, 155–163 (2006).
  3. Lee, D. & Huestis, M. A. Current knowledge on cannabinoids in oral fluid: Current knowledge on cannabinoids in oral fluid. Drug Test. Anal. 6, 88–111 (2013).
  4. Hubbard, J. A. et al. Biomarkers of Recent Cannabis Use in Blood, Oral Fluid and Breath. J. Anal. Toxicol. 45, 820–828 (2021).
  5. Robertson, M. B. et al. Correlation between oral fluid and blood THC concentration: A systematic review and discussion of policy implications. Accid. Anal. Prev. 173, 106694 (2022).
  6. Industry Insights Quest Diagnostics Drug Testing Index™ 
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