Drug Testing in Regulated and Safety-Sensitive Industries

Regulated drug testing is defined by the rule that covers the worker and the function actually performed. A job title alone does not determine coverage. In U.S. transportation programs, 49 CFR Part 40 supplies the common testing procedures, while an operating-agency rule identifies who is covered, which test reasons apply, and what conduct is prohibited.

This guide is an educational overview, not legal advice. Employers and workers should verify the current regulation and agency guidance for the exact position. For the broader subject, return to Drug Testing: The Complete Guide.

Part 40 and the operating-agency rules

Part 40 governs how DOT drug and alcohol tests are conducted. It addresses collection, laboratory analysis, Medical Review Officer review, alcohol testing, refusals, record handling, and the return-to-duty process. It does not by itself decide whether a particular employee must be tested.

Coverage and test requirements come from the applicable operating-agency rule:

  • FMCSA: 49 CFR Part 382 for covered commercial drivers.
  • FAA: 14 CFR Part 120 for covered aviation employers and safety-sensitive functions.
  • FRA: 49 CFR Part 219 for regulated railroad service.
  • FTA: 49 CFR Part 655 for covered public-transportation recipients, contractors, and safety-sensitive functions.
  • PHMSA: 49 CFR Part 199 for covered pipeline operations, maintenance, and emergency-response functions.
  • USCG: maritime requirements, including 46 CFR Parts 4 and 16.

Read the detailed guides to commercial-driver testing, aviation testing, and railroad and public-transit testing.

Who is safety-sensitive?

A safety-sensitive employee performs a function identified by the governing regulation as having a direct relationship to transportation or public safety. Examples include driving certain commercial vehicles, performing specified aviation duties, operating or dispatching transit vehicles, maintaining covered equipment, and performing regulated railroad service.

Coverage turns on duties, not labels. A supervisor who can be called to perform a covered function may be subject to the rule while doing or being available for that work. A person employed by a contractor may also be covered when the agency rule reaches contracted safety-sensitive functions.

Common test reasons

Agency rules may require some or all of the following:

  • pre-employment testing before covered work begins;
  • random testing using a scientifically valid, neutral selection method;
  • reasonable-suspicion or reasonable-cause testing based on trained observations;
  • post-accident testing when rule-specific thresholds are met;
  • return-to-duty testing after a violation and Substance Abuse Professional process; and
  • unannounced follow-up testing directed by the Substance Abuse Professional.

The triggers and timing are not identical across industries. An employer should never substitute a general company standard for the applicable agency rule.

Specimens and laboratories

Part 40 authorizes urine and oral-fluid specimens, but implementation must meet every regulatory condition. Only specimens screened and confirmed at laboratories certified by HHS for the methodology may be used. Point-of-collection drug tests, hair tests, and instant tests are not authorized as DOT tests.

DOT stated in its May 2026 rulemaking that oral-fluid testing was not yet operational because the required laboratory capacity was unavailable. Employers should check current DOT and HHS laboratory information before choosing a methodology. When the rule requires a directly observed collection and oral fluid is unavailable, the current Part 40 procedure controls.

The role of the MRO and SAP

A laboratory-confirmed nonnegative drug result does not go directly to the employer as a verified positive. A qualified Medical Review Officer reviews the result, contacts the employee when required, and evaluates whether a legitimate medical explanation exists. Learn more about the MRO’s role.

After a verified positive, refusal, or other DOT drug-and-alcohol violation, the employee must be removed from safety-sensitive duties. Returning to covered work requires evaluation by a qualified Substance Abuse Professional, successful completion of the recommended education or treatment, a follow-up evaluation, and a negative return-to-duty test. Follow-up testing then occurs according to the SAP’s plan.

DOT and non-DOT tests must remain separate

An employer may operate a separate company testing program where lawful, but it must not represent a non-DOT test as a DOT test. Federal forms, specimens, and results may not be repurposed to expand the DOT panel or test for unrelated purposes. Policies should distinguish the authority, form, panel, decision maker, and consequence for each program.

Records, privacy, and consistency

Regulated programs impose record-retention, disclosure, and reporting duties. Access should be limited to authorized persons, and agency-specific reporting systems may apply. Employers remain responsible for compliance even when collectors, laboratories, MROs, consortiums, or third-party administrators perform services.

Construction and other high-hazard work

Not every safety-sensitive workplace is governed by DOT rules. Construction, manufacturing, utilities, healthcare, and other high-hazard industries may use testing under state law, contracts, collective-bargaining agreements, or written policy. Those programs should be analyzed separately. See Construction-Industry Drug Testing and Drug Testing for Safety-Sensitive Positions.

Sources

Legal and evidence review: October 29, 2026. Verify current agency rules before making a compliance decision.