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Employer FAQs


Employers of safety-sensitive transportation employees play a vital role in ensuring the safety of their employees and the traveling public.  

The following are some of the questions the Office for Drug and Alcohol Policy and Compliance (ODAPC) and the Program Managers have received which did not require an interpretation but rather a general response. As such, the ODAPC staff thought that those subject to Department of Transportation (DOT) testing would benefit from the responses already provided.

These responses do not substitute for the regulations found in 49 CFR Part 40 or any other DOT agency or United States Coast Guard (USCG) specific regulation. If you have a question about the DOT drug and alcohol testing program rules, read the regulatory text.

Employer FAQs

Which employees are subject to testing?
What specimens are collected for testing?

For what drugs are the urine specimens tested?

When are tests conducted?
What is a refusal to test?
How would I handle an employee's verified positive drug test, refusal to test, or alcohol violation?
The Medical Review Officer (MRO) reported a 'dilute' test result, what do I do now?
Am I required to report statistical drug and alcohol testing data annually to DOT?

Which employees are subject to DOT testing?

Each DOT Agency lists the safety-sensitive duties that must be tested.  For a list of all safety-sensitive duties by DOT Agency, go to

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What types of specimens are collected for DOT testing?

For DOT drug testing, a urine specimen is collected and sent to a certified laboratory for analysis ( urine specimens are authorized, and devices that provide instant results are not authorized for DOT testing.

For DOT alcohol testing, breath or saliva testing devices are approved for initial (screening) tests.  A Breath testing device is required for all confirmation tests. The specimen is collected and analyzed by an approved alcohol testing device.

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What drugs are tested on a DOT test?

        See 49 CFR Sections 40.85 and 40.87 for the list of drugs.

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When are tests conducted?

Each DOT Agency identifies the types of tests required by their industry, which may be different.  The following is a list of most commons types of testing:

  • Pre-employment testing:
    • must occur prior to hire or transfer into a safety-sensitive function.
  • Random testing:
    • must be unannounced, spread reasonably throughout the calendar year, and selected using a scientifically valid method in which each covered employee has an equal chance of being tested.
  • Reasonable Suspicion/Cause testing:
    • requires an observation and determination by a trained supervisor.
  • Return-to-duty and Follow-up testing:
    • occurs after an employee's verified positive drug test result or refusal to test and a Substance Abuse Professional (SAP) determined the employee successfully completed his or her education or treatment.
    • The employee must take a return-to-duty test and the employer must have a negative result prior to returning to safety-sensitive functions. 
    • The follow-up testing must be conducted in accordance with the SAP’s recommendations, and must include a minimum of 6 follow-up tests in the first 12 months.
    • Depending on the SAP's recommendations, follow-up testing may continue for up to 60 months. 
    • An employer cannot add more testing or change the frequency prescribed by the SAP.  If you are unsure about the testing schedule, contact the SAP.


  • USCG Specific Testing:
    • Periodic:
      • Occurs during the issuance or renewal of a license or merchant mariner’s document
    • Serious Marine Incident:

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What is a refusal to test?
According to 49 CFR § 40.191 and 40.261, a refusal includes, but is not limited to:

  • Failure to appear at the test collection site at the designated time or not at all.
  • Failure to remain at the testing site until the collection is completed.
  • Adulteration (a urine specimen containing a substance or a concentration of a substance inconsistent with human urine).
  • Substitution of a urine specimen containing creatinine and specific gravity levels inconsistent with human urine.
  • Failure to cooperate with any part of the testing process. 

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What would I do if an employee violates the testing rules with a verified positive drug test, refusal to test, or alcohol violation?

  • Upon notification of a violation, you must immediately remove the employee from performing safety-sensitive duties.
  • You must provide the employee with a list of Substance Abuse Professionals (SAP), whether you decide to rehabilitate the employee or terminate employment.
    • Applicants who fail or refuse a drug and/or alcohol test must also receive a SAP list.
  • If you choose to rehabilitate your employees, you must follow the return-to-duty requirements outlined in 49 CFR part 40 - Subpart O, which start with an initial evaluation with a SAP.
  • FAA Only
    • If your employee holds a medical certificate issued under 14 CFR part 67, you must report it to the FAA’s Federal Air Surgeon.  For more information, visit the FAA’s web site at

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 The Medical Review Officer (MRO) reported a 'dilute' test result, what do I do now?

  • If the result is reported by the MRO to the employer as positive and dilute, the employer must treat the result as a verified positive test.
  • If the result is reported by the MRO to the employer as a negative and dilute with no MRO instructions for recollection under direct observation, the employer may accept the result as a "negative" test or may require the employee to submit to another test if the employer has a company policy requiring a re-collection.
  • If the result is reported by the MRO to the employer as negative and dilute with MRO instructions for recollection under direct observation, the employer must ensure that the employee reports immediately for a re-collection under direct observation.
    • NOTE: If the employee declines to take this test, the employee has refused the test.
  • For clarification regarding an employer's actions on negative dilute test results, read a Q&A issued in September 2001.

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Am I required to report statistical drug and alcohol testing data annually?

Each DOT Agency identifies which employers must report an annual Management Information System (MIS) report.  To find out if this applies to you, go to

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Last updated: Monday, June 15, 2020