While labs are ultimately permitted to devise their own thresholds for non-federal employee testing, most facilities adhere to the the Substance Abuse and Mental Health Services Administration’s proposed guidelines. For oral testing, these include:
- THC (marijuana): 4 nanogram per milliliter for initial testing and 2 ng/mL for confirmatory testing
- Benzoylecgonine (cocaine): 15 ng/mL for initial testing and 8 ng/mL for confirmatory testing
- 6-acetylmorphine (heroin): 3 ng/mL for initial testing and 2 ng/mL for confirmatory testing
- Amphetamine/Methamphetamine (meth): 25 ng/mL for initial testing and 15 ng/mL for confirmatory testing
- Hydrocodone/Hydromorphone/Oxycodone/Oxymorphone (opiates): 30 ng/mL for initial testing and 15 ng/mL for confirmatory testing
- v: 25 ng/mL for initial testing and 15 ng/mL for confirmatory testing
Limitations in Oral Drug Testing
While oral drug testing does have numerous benefits, this does not mean there aren’t limitations that those employing oral swabs should keep in mind. The most notable disadvantage is the time drugs or their metabolites are present in saliva. The testing time range is generally far shorter than other methods, which means that users can simply take a few days off of using, test clean, and return to use. Further, medication use can potentially interfere with testing, leading to inconclusive results. For example, cough medicines with codeine could impact an opiate test. Some drugs cannot be identified in the saliva at all, leading to a lack of testing opportunity.
Some individuals do attempt to cheat oral drug tests, often by drinking a lot of water, chewing gum, eating mints, or using products sold specifically to interfere with the state of saliva. However, these efforts are usually unsuccessful. To prevent food substances from tampering with results, those undergoing testing are usually required to maintain an empty mouth for at least 10 minutes prior to testing. So far, no substances sold to tamper with saliva have proved effective.
Due to the non-invasive nature of testing, mouth swab tests offer compelling opportunities for drug, disease, and genetic testing for many different applications. As the process is easier and room for error is lower, oral testing is gradually replacing other forms of screening when opportunity allows.