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Oral Fluid: Testing for Impairment

Companies should know if their employees are using drugs while at work. Now there’s a way of testing that potentially proves likely impairment on the job. Depending on the drug and/or drug metabolite tested for and the laboratory cutoff levels used, oral fluid testing can suggest recent drug use.

DriverCheck’s menu of sample methods includes oral fluid testing. However, there are a few things to consider before using this sample method.

What industries are using oral fluid testing?
What are the benefits?
Can oral fluid testing prove that a substance was used within a specific time frame?
Can oral fluid testing identify the frequency of drug use?
How reliable is oral fluid testing?
Is the Point of Care Testing device different from the lab-based testing device?
Are there different brands of oral fluid testing devices?
Lab-based vs. POCT. How do they work?
What are the cutoff levels for oral fluid testing?
Has oral fluid testing technology been challenged in court?

What industries are using oral fluid testing?

Our clients that have shown great interest are in the construction, railroad and oil industries. (The technology is not yet approved for the DOT transportation industry.) The majority of testing is still done using urine samples, but the growing interest in oral fluid testing stems in part from a benchmark case which, in spirit, endorsed oral fluid testing over urine testing because of the potential for oral fluid testing to demonstrate impairment while on duty.

What are the benefits?

Depending on the positive test cutoff levels used, there is more potential to identify if someone likely used drugs (marijuana, for example) at work, and was therefore likely impaired on the job.
Each test is effectively directly observed, thereby minimizing risk for specimen tampering.
Collections are more convenient because there is no need for a washroom.

Can oral fluid testing prove that a substance was used within a specific time frame?

It is important to note that oral fluid testing only indicates “likely usage” within a recent timeframe, not “definite usage.” For example, “likeliness” of THC use within certain time periods is possible because all that is measured is pure THC deposited in the oral cavity without metabolites being excreted by the saliva glands or excreted through the buccal mucous membrane. Other substances may prove difficult because while the substance itself may be present, metabolites may also be present (via salivary gland excretion or excreted from the bloodstream through the mucous membrane), or both the raw substance and its metabolites may be present. Some detection timeframes are identical to urine testing timeframes.

As well, there is no direct correlation between “likely recent usage” and legally defined “impairment” levels as you have with breath alcohol testing. The courts seem to be starting to recognize that lab-based oral fluid testing has a closer correlation to impairment than urine testing when it can be concluded that drug use likely occurred while on duty (and if the drug was likely used while on duty, impairment likely occurred while on duty).

Can oral fluid testing identify the frequency of drug use?

Oral fluid testing of any type (POCT or lab based) cannot be used to speculate or verify frequency or longevity of drug use by the specimen donor.

How reliable is oral fluid testing (lab-based and POCT)?

Lab-based testing is the most reliable method. POCT oral fluid testing is currently not considered to be as accurate as lab-based testing. As an example, according to laboratories and other sources, the oral fluid POCT for THC is not considered to be reliable enough to use because the cutoff has to be set quite high in order to obtain a positive result. As such, the detection time window is extremely short. That is why we currently do not recommend the use of POCT oral fluid tests at this time. We continue to monitor the effectiveness of products that are available on the market and would be pleased to provide this service when the devices are reliable.

Is the Point of Care Testing device different from the lab-based testing device?

Yes. The POCT device collects the oral fluid and tests it. The lab-based device simply collects and holds the saliva for transport to the lab.

Are there different brands of oral fluid testing devices?

Yes, there are many different brands and manufacturers of POCT oral fluid kits and each lab will have its own lab-based kit.

Lab-based vs. POCT. How do they work?

Drug testing involves two distinct testing methods – an initial general screening test technology, and, if the screening test is non-negative, a second much more accurate and precise testing technology is applied called confirmation test technology. POCT is an initial screening technology test only, and, in itself, is not as accurate as laboratory initial screening technology, meaning there is a higher risk of obtaining false negative or false positive screening test results. Any non-negative screening test (whether POCT or lab-based) requires confirmation testing be done in order to accurately verify whether or not the test is truly positive for a given substance or finding. For oral fluid confirmation testing, the technology/methodology currently used can be either Gas Chromatography/Mass Spectrometry (GC/MS), or Liquid Chromatography/Mass Spectrometry/Mass Spectrometry (LC/MS/MS).

What are the cutoff levels for oral fluid testing?

HHS-approved cutoff levels have not yet been identified in North America, however, there are recommended cutoff levels contained in the Canadian Model for a Safer Workplace. Some laboratories have adopted DOT and HHS proposed cutoffs from a few years ago. Some employers have worked independently with laboratories and kit providers to use cutoffs designed for specific purposes. A scientific study by Cone and Huestis (2007) identifies a number of different cutoffs, which may become the benchmark in North America.

Has oral fluid testing technology been challenged in court?

As of yet, there is no established legal track record in Canada for oral fluid testing solely in its capacity as a testing technology, since the technology is still evolving. Where legal challenge in Canada has occurred, it has been more in the context of how an employer has worded and applied its testing policy, which, by coincidence, might have engaged oral fluid testing as a component. The scientific technology itself has not been challenged.