Mandated drug testing helps promote, maintain and improve safety in the workplace. Employees that use or abuse drugs on the job pose a direct risk to themselves, their team, and in some cases, the general public. 

That said, an employer has the right to maintain an efficient, productive and competitive workforce. Drug use and abuse can lead to increased absenteeism, workers compensation claims, liability insurance rates and productivity issues.

The most common drugs we test for are alcohol, amphetamine, cocaine, methamphetamine, opiates, oxycodone, phencyclidine, THC, barbiturates, benzodiazepines, methadone, and MDMA.

Please visit our Drugs of Abuse page for a more comprehensive table that highlights the drugs we test for as well as their common street names, trade names, techniques of ingestion, effects, and more.

It’s important to understand that everyone is different. Each individual metabolises drugs differently depending on a multitude of factors, from height and weight to stress levels, illness and diet. That said, there’s no sure-fire way to determine how long any type of drug will stay in someone’s system; however, here is a table that offers a rough drug detection guideline.

No. Drug testing by blood, urine, or saliva can only detect whether or not a specific drug or drug metabolite is present at the time the test is performed. While there are very broad estimates (see chart above) as to how long a particular drug may have been in the system, no fluid based drug test, regardless of method, is intended to include a time variable. That said, a forensic hair core analysis for drugs can be utilized to determine historical drug use up to 90 days.

These tables indicate the standardized threshold concentration levels for lateral flow immunoassay tests established by the international regulating authorities. These levels are reviewed and updated periodically to conform to new data on drug development, technology and testing statistics. Concentration is expressed in nanograms per milliliter.

There are literally hundreds of brand name and generic drugs being prescribed today. If you have a question about a specific prescribed medication, you will need to know the general classification of that medication to determine if it will test positive on any of the specific drug test panels such as opiates, amphetamine, methamphetamine, benzodiazepines and barbiturates.

For general classifications on prescription drugs you can either ask your pharmacist or go online to and enter the name of the prescription drug to determine its general classification and pharmacology.

That said, commonly ingested substances such as vitamins, penicillin, aspirin, caffeine and acetaminophen (Tylenol) will not affect the results of a drug screening as the tests are drug and drug metabolite specific. Because these commonly ingested substances are chemically and structurally different after they’re metabolized by the body from the drugs being tested for, they will under most circumstances not interfere with or compromise test results.

Immunoassay techniques used by laboratories for initial testing purposes will detect the presence of a specific drug above a threshold level with 95% confidence. These techniques use antibodies which recognize the shape of a specific drug and produce a positive result. However, other compounds and drugs which are similar in shape to the drug of interest may also react with the antibody, thus producing a positive result. This phenomenon, called cross-reaction, may potentially lead to a false positive with drugs. For this reason, confirmation using a chemically different technique is essential.

In order to prove beyond a doubt the identity of a drug present in a sample, GC/MS is the only technique which can be used. GC/MS produces a fragmentation pattern of a compound which is reproducible and unique to that compound and hence undeniable identification. This fragmentation pattern is analogous to a fingerprint. GC/MS is the only analytical technique which will withstand legal scrutiny.

The MRO plays an ongoing and integral role in the drug testing process, acting as an impartial gatekeeper and advocate for the test’s accuracy and integrity. They provide a quality assurance review of the process for both the technology used as well as the staff performing the test.

For drug screenings, the chosen cutoff optimizes drug detection but minimizes the number of false-positive results. That said, a negative sample doesn’t necessarily mean it’s drug-free; it might contain a drug at a lower concentration than the defined cutoff.
Screening and confirmation testing are performed using different methodologies that necessitate different cutoff levels. The cutoff levels of an immunoassay screen are typically higher than those of a more sensitive GC/MS or LC/MS/MS confirmation test because they screen for a larger group of parent compounds, metabolites and other structurally similar compounds.

If a screening test detects a drug above the screening cutoff level, the presumptive positive specimen will be sent to GC/MS or LC/MS/MS confirmation testing. Usually these individual compounds are present in concentrations much lower than the total immunoassay response, which results in the cutoff levels being lower for the GC/MS or LC/MS/MS test.

Long story short, the screening test is very generic while the confirmation test is quite specific.

For example:
The cutoff for marijuana on the screen is 50ng/ml, which is a composite of all 31 metabolite concentrations. If the sample is below this level, the test is over a passing status. If the sample is over 50 ng/ml, the sample is sent to GC/MS for confirmation testing. The cutoff for the confirmation is set lower at 15 ng/ml because the machine only identifies one of the 31 metabolites, which is the 11-nor-D-9-tetrahydrocannabinolic acid. To pass, the one metabolite must be below the 15 ng/ml cutoff.

No. Urine concentrations of THC above the cutoff sensitivity level of the test, or a positive result, are not possible by exposure to second-hand smoke.

If the sensitivity cutoff level of the test is the revised standard of 2000 ng/ml OPI, this is not possible. Sensitivity standards were raised in the year 2000 from 300 ng/ml to 2000 ng/ml OPI to eliminate the possibility of false-positive results that were possible from consumption of large quantities of poppy seeds or poppy seed paste at the lower sensitivity level.