Taking The Smoke And Mirrors Out Of Drug Testing
Posted Friday, September 26th, 2014 by
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After interviewing several job applicants, you’ve finally found one with all of the qualifications required and an impressive work history. Plus, their background check came back spotless. Just when you thought you found your company’s next great performer, the drug test comes back positive.
Today’s drug testing methods, while highly effective for identifying unmanaged substance abuse problems of job applicants and employees, can sometimes produce false positive results. Ingestion of certain foods and medications can cause this, and is a leading reason why confirmation testing and a competent Medical Review Officer (MRO) are so critical to an effective workplace drug testing program.
A workplace drug test begins with an initial screen of the collected specimen using techniques referred to as immunoassays. Immunoassay screening involves use of specific antibodies to detect common drugs of abuse or their metabolites. One problem with immunoassay screening, however, is the potential for a false positive result. Consequently, a 2nd confirmatory test (such as GC/MS – gas chromatography/mass spectrometry) is needed to confirm the positive result from the initial screen. However, even with confirmation testing, a false positive result can sometimes still seep through.
Specific detection cut-off levels are used by the testing laboratories to reduce false positive results. Though cut-off levels are highly reliable, false results cannot entirely be eliminated. Consider, for example, the cut-off levels for opiate detection were raised in 1998 by the Department of Health & Human Services (HHS) from 300 ng/mL to 2000 ng/mL to avoid false positives that can result from poppy seed ingestion. However, due to the more stringent requirement, a false-negative can then result.
The consumption of poppy seeds can produce false positive results and, in fact, as little as one teaspoon of poppy seeds can trigger a positive test result (even if consumption occurred two or three days prior to testing). Most poppy seed bagels and muffins contain more than one teaspoon, so a false positive can easily occur. Another example involves ingestion of hemp-containing foods, which can result in an initial detection of marijuana.
Some prescription and over-the-counter drugs are also known to cross-react with initial screening and can cause false positive results. For example, over-the-counter cold medications and some antidepressant medications can trigger false positive results for amphetamines or benzodiazepines.
Some antibiotic and HIV medications can produce false positive results for opiates.
The combination of confirmation testing with an MRO – a licensed medical physician with separate qualification in substance abuse testing – are, therefore, essential to an effective workplace testing program. An MRO will review and properly interpret drug test results reported by the testing laboratory, evaluate medical information presented by the job applicant or employee and, finally, make a useable and defendable determination for the employer. An MRO, particularly, will help protect the employer from dealing with:
- The prospect of a false positive result reported by a laboratory.
- A job applicant’s or employee’s claim that, rather than through illicit use, a positive drug test result was caused by certain food or legal use of medication.
- Access to private medical information.
MRO’s are also critical for evaluating diluted results, or those that may be suspected of adulteration or substitution. Without confirmation testing and an MRO, a workplace testing program can never be as effective as it should.
This publication is for informational purposes only and nothing contained in it should be construed as legal advice. We expressly disclaim any warranty or responsibility for damages arising out this information. We encourage you to consult with legal counsel regarding your specific needs. We do not undertake any duty to update previously posted materials.