What Is the Difference between a Screening Test and a Confirmation Test in DOT Testing?

A screening test is the first test, used to separate negative results from those that need more testing. A confirmation test is a second, separate test that checks a screening result at or above the cutoff. Under 49 CFR Part 40, both DOT drug tests and DOT alcohol tests use the two steps, but the steps work differently for each.

For drug tests, Part 40 calls the screening step an initial drug test. Under 49 CFR 40.3, an initial drug test is "The first test used to differentiate a negative specimen from one that requires further testing for drugs or drug metabolites," and a confirmatory drug test is "A second analytical procedure performed on a different aliquot of the original specimen to identify and quantify a specific drug or drug metabolite." Both steps take place at the laboratory, because 49 CFR 40.210 allows only specimens screened and confirmed at HHS-certified laboratories.

A confirmed laboratory result is not yet the final result. Under the 40.3 definition of a verified test, a laboratory result is verified only after review and final determination by the Medical Review Officer (MRO).

For alcohol tests, the screening test can use breath or saliva, and the confirmation test uses breath only. Under 49 CFR Part 40:

• A screening test determines whether an employee may have a prohibited concentration of alcohol in a breath or saliva specimen (40.3)
• A screening result of less than 0.02 goes to the DER, and a result of 0.02 or higher leads to a confirmation test (40.247)
• The confirmation test uses an evidential breath testing device (EBT) and provides quantitative data about the alcohol concentration (40.3)
• The waiting period before the confirmation test lasts at least 15 minutes from the end of the screening test, and the confirmation test should begin as soon as possible, but not more than 30 minutes after the screening test is completed (40.251(a)(1))
• Only saliva or breath for screening tests and breath for confirmation tests, using approved devices, are permitted (40.277)

Learn Laws® offers DOT Breath Alcohol Technician Training, an online course with Model BAT Course training, EBT device training and seven live mock tests under 49 CFR 40.213.

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