Drug Testing Glossary

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49 CFR Part 40 (Part 40)

The federal regulation that sets out how every DOT drug and alcohol test is collected, analyzed, reviewed and reported. Every DOT-regulated industry tests under it, and employers can't change it.
49 CFR Part 40 (eCFR) ↗

6-Acetylmorphine (6-AM)

A short-lived substance that appears only when heroin breaks down. That makes it the one marker that separates heroin from prescription opiates. It clears quickly, so it's often absent even when morphine is found.
DOT §40.85 ↗

A

Actual knowledge

A trigger for consequences that needs no test at all. Direct observation of use, an admission, or certain citations can be enough on their own, so a positive result isn't the only thing with effect.
FMCSA Clearinghouse ↗

Adulterated specimen

A sample the laboratory found evidence that something was added to. In regulated testing, it's treated as a refusal to test, which carries the same consequences as a positive result.
49 CFR Part 40 (eCFR) ↗

Alcohol Testing Form (ATF)

The federal form that records an alcohol test from start to finish: your identification, the device used, the readings and your signature. It's the alcohol counterpart to the custody and control form used for urine.
49 CFR Part 40 (eCFR) ↗

Aliquot

A measured portion poured off from your sample for a particular test. One collection yields several aliquots, so the laboratory can screen, confirm, and check validity without asking you for more.
HHS Mandatory Guidelines (2026) ↗

B

Benzoylecgonine

The main substance your body makes from cocaine, and what federal confirmation testing looks for. Finding it means your body processed cocaine. It isn't a substance present in cocaine itself.
DOT §40.85 ↗

Breath alcohol concentration (BAC)

The figure a breath alcohol test produces, expressed as grams of alcohol per 210 liters of breath. Federal alcohol testing uses this number instead of a blood draw.
49 CFR Part 40 (eCFR) ↗

Breath Alcohol Technician (BAT)

The trained person who runs a breath alcohol test and completes the paperwork. It's a separate role from the urine collector, with its own training requirements.
49 CFR Part 40 (eCFR) ↗

C

Cancelled test

A test that failed on procedure, such as a broken chain of custody or a flaw that can't be corrected. It counts as nothing at all. You can't rely on it as a negative, and it can't be used against you as a positive.
49 CFR Part 40 (ODAPC) ↗

Chain of custody

The documented record of everyone who handled your sample between collection and analysis. It exists so a result can be tied to you and to nobody else.
SAMHSA — Forms & guidelines ↗

Confirmatory test

The second, more specific test run on anything the initial test flags. It identifies the individual compound and measures it against a lower cutoff. Both thresholds must be met before a positive can be reported.
49 CFR Part 40 (eCFR) ↗

Consortium/Third-Party Administrator (C/TPA)

An outside company that runs testing programs for an employer, handling things like random selection, scheduling, and record-keeping. Small operators often use one because they can't run a program alone. The employer stays legally responsible either way.
49 CFR Part 40 (eCFR) ↗

Control line

The line on a home test that confirms the device worked. If it's missing, the result is invalid however the rest of the test looks, and it shouldn't be read as positive.
FDA — Home use tests ↗

Cross-reactivity

When the antibody in a screening test binds to something other than the drug it was designed to find, the test flags anyway. It's the usual cause of a false positive on an initial screen, and it's why confirmation by a different method exists.
FDA — Drugs of abuse tests ↗

Custody and control form (CCF)

The standard form that travels with a federal test specimen, recording the collector, the specimen identification number, whether the collection was observed, and every signature along the chain.
SAMHSA — Forms & guidelines ↗

Cutoff concentration

The level at or above which a laboratory reports a result as positive. Below it, the result is reported negative even if a trace was detected. The cutoff is a reporting threshold and says nothing about how much was taken.
DOT §40.85 ↗

Creatinine

A waste product the body excretes at a fairly steady rate. Labs measure it to judge whether a sample is genuine human urine at a normal concentration. A low reading is usually what's behind a dilute result.
HHS Mandatory Guidelines (2026) ↗

D

Designated Employer Representative (DER)

The person at your employer authorized to receive test results and to remove someone from a safety-sensitive role. Results go to the DER, not to your manager.
49 CFR Part 40 (eCFR) ↗

Detection window

The span during which a test can still detect a substance after use. It depends on the substance, the sample type, and the cutoff together, so there's no fixed number. That's why the same person can test positive in urine and negative in saliva on the same day.
FDA — Drugs of abuse tests ↗

Dilute specimen

A sample more watery than a genuine one would normally be. Dilute describes concentration only, so a sample can be both dilute and negative. It usually leads to another collection.
49 CFR Part 40 (eCFR) ↗

Directly observed collection

A collection watched by an observer of the same gender. Most collections aren't observed. The rules spell out when observation is justified, and the decision isn't left to the collector.
49 CFR Part 40 (ODAPC) ↗

Drug-free workplace program

A voluntary program that several states run through workers' compensation. An employer that follows the state's testing rules gets a premium discount and certain defenses after an accident. In states with no general testing law, it's often the reason employers test at all.
Georgia State Board of Workers' Compensation ↗

E

Employee Assistance Program (EAP)

An employer-funded, confidential counseling and referral service. Several state programs expect one alongside testing, and some policies send a first positive here instead of going straight to dismissal.
SAMHSA — Drug-Free Workplace ↗

Ethyl glucuronide (EtG)

A minor byproduct of alcohol that stays in urine well after the alcohol itself is gone. That's why it's used in abstinence monitoring and not in fitness-for-duty testing. It sits outside the federal program entirely, since DOT alcohol testing measures alcohol in breath or saliva.

Evidential Breath Testing device (EBT)

A breath alcohol instrument approved for results that can carry consequences. Screening-only devices can't be used that way. Federal programs require the model to appear on a published list of conforming products.
49 CFR Part 40 (eCFR) ↗

F

FMCSA Drug and Alcohol Clearinghouse (Clearinghouse)

The federal database that records drug and alcohol program violations by commercial drivers. Employers query it, so a recorded violation follows the driver from job to job.
FMCSA Clearinghouse ↗

Follow-up testing

A plan of unannounced tests you're placed on after returning to duty. Your employer gets the schedule and you never see it, because it's meant to be unpredictable.
DOT notice (Mar 2026) — SAP ↗

G

Gas chromatography–mass spectrometry GC/MS (GC/MS)

A confirmation method federal programs rely on. It separates a sample into its components and identifies each one by mass, so a GC/MS result names a specific molecule instead of a drug class. This is the step that turns a screening flag into a finding.
HHS Mandatory Guidelines (2026) ↗

H

HHS-certified laboratory

A laboratory certified by the Department of Health and Human Services to analyze federal workplace test specimens. As of August 2026, labs are certified for urine only, and none for oral fluid.
HHS certified labs (Aug 2026) ↗

I

Immunoassay

The antibody-based method used for the first, low-cost pass at a sample. It shows whether something from a drug class may be present, without identifying exactly what. Anything it flags has to be confirmed by a different method before it means anything.
FDA — Drugs of abuse tests ↗

Initial test

The first test run on every sample, built to be fast and sensitive. It reacts to families of similar compounds, so it flags samples for further testing without identifying anything specific. It's also called the screening test.
49 CFR Part 40 (eCFR) ↗

Invalid result

A result where the laboratory couldn't get a usable answer. It goes through medical review and usually leads to another collection. An invalid result doesn't accuse you of anything.
49 CFR Part 40 (eCFR) ↗

L

Limit of detection (LOD)

The smallest amount an instrument can reliably detect. It sits below the cutoff, which is why a laboratory can detect a trace and still report the result as negative. The cutoff is a reporting decision, while the limit of detection marks the edge of what the instrument can find.
HHS Mandatory Guidelines (2026) ↗

Liquid chromatography–tandem mass spectrometry (LC-MS/MS)

A confirmation method that does the same job as GC/MS but works better for compounds that don't survive the heat of gas chromatography, including several opioids and cannabis analytes. Federal programs accept it alongside GC/MS.
HHS Mandatory Guidelines (2026) ↗

M

Medical Review Officer (MRO)

A licensed physician who reviews drug test results before your employer sees them, checks the paperwork, and contacts you so you can explain a lawful medical reason for a positive.
49 CFR Part 40 (ODAPC) ↗

Metabolite

A compound your body produces while processing a substance. Urine drug tests usually look for metabolites instead of the original drug. For example, a marijuana urine test measures THCA (THC-COOH), not THC.
DOT §40.85 ↗

N

Non-negative

Laboratory wording for a sample the initial test flagged and now needs confirmation. Nothing has been established yet. You may also see it called a preliminary or presumptive positive.
49 CFR Part 40 (ODAPC) ↗

O

Off-duty conduct statute

A state law that makes it unlawful to act against an employee for lawful activity away from work, on their own time. Some are written around "lawful products." Whether cannabis is covered depends on whether "lawful" means lawful under state law alone or under federal law too. States split on that question, and it decides most cases.
Mont. Code Ann. § 39-2-313 ↗

Office of Drug and Alcohol Policy and Compliance (ODAPC)

The office inside the US Department of Transportation that writes and interprets the federal testing rules in Part 40. Where the rules are ambiguous, its published notices are what practitioners rely on.
DOT ODAPC ↗

Opiate

A drug derived directly from the opium poppy, such as morphine and codeine. Heroin is made from morphine. "Opiate" is narrower than "opioid," which also covers semi-synthetics like oxycodone and synthetics like fentanyl. Panels often use one word and test for the other, so check the substance list, not the label.
DOT §40.85 ↗

Oral fluid

The saliva sample collected with a mouth swab. It has authorized federal cutoffs, far lower than urine's, but no laboratory is certified yet to analyze it for federal programs.
HHS certified labs (Aug 2026) ↗

P

Point-of-collection test (POCT)

A test read on the spot with an instant device, where the sample is given, instead of at a laboratory. It's fast and cheap but only a screen. Several states bar permanent employment action on an unconfirmed instant positive, and federal programs don't accept one as a result at all.
FDA — Home use tests ↗

Post-accident testing

Testing required after certain accidents. For commercial drivers, it's always required after a fatality. Otherwise, it's required only when the driver gets a citation for a moving violation and the accident involved either an injury treated away from the scene or a vehicle that had to be towed.
49 CFR §382.303 ↗

Presence-based standard

A rule that treats detecting a substance as what matters, whether or not you were affected at work. The alternative ties consequences to impairment, or to a causal link with an incident. Which approach a state takes usually matters more than its testing procedures.

Prohibited status

A commercial driver's status in the Clearinghouse after a violation. It means they may not perform safety-sensitive functions, including driving commercially, until the return-to-duty process is complete.
FMCSA Clearinghouse ↗

Q

Qualitative test

A test that indicates whether something may be present, without measuring how much. The FDA describes consumer at-home drug tests this way.
FDA — Home use tests ↗

Quantitative test

A test that reports how much of a substance is present, as a number. Confirmation testing is quantitative. Compare a qualitative test, which reports only positive or negative.
HHS Mandatory Guidelines (2026) ↗

R

Random testing

Testing where names are drawn from a pool by a method the employer cannot influence. Each DOT agency sets a minimum annual percentage of the pool that must be tested.
DOT — random testing rates ↗

Reasonable suspicion testing

Testing based on a trained supervisor's specific, contemporaneous observations of appearance, behavior, speech or body odor. Rumors, tips and general performance concerns don't meet the standard.
49 CFR Part 40 (ODAPC) ↗

Refusal to test

A whole category of behaviors that goes beyond saying no. Failing to appear, leaving before the process is complete, not providing a sample, or interfering with one all count. A refusal carries the same consequences as a positive result.
49 CFR Part 40 (ODAPC) ↗

Return-to-duty test (RTD)

A directly observed test taken after a Substance Abuse Professional confirms you have complied with their recommendations. A negative result is required before you may perform any safety-sensitive function.
49 CFR Part 40 (ODAPC) ↗

S

Safety-sensitive function

The work that federal testing rules attach to. It's broader than the obvious task. For a driver, it covers more than time behind the wheel, and each agency defines it in its own rule.
49 CFR Part 40 (eCFR) ↗

Safety-sensitive (state law)

State statutes use this phrase too, but define it differently from federal rules. Some states define it by risk of death, others by serious property or environmental damage, and some leave it to the employer. The federal meaning doesn't carry over to state law.
W. Va. Code §§ 21-3E-2 to 21-3E-16 ↗

Shy bladder procedure

The defined process when someone can't produce enough urine. They get a set period with fluids, and if that doesn't work, a medical evaluation checks for a genuine medical explanation. It isn't treated as an automatic refusal.
49 CFR Part 40 (ODAPC) ↗

Specific gravity

How dense a sample is compared with water. Labs read it together with creatinine to decide whether urine is dilute, substituted or normal. Drinking a lot of water before a test moves both numbers at once.
HHS Mandatory Guidelines (2026) ↗

Split specimen

The second bottle your sample is divided into at collection. If a positive is reported, you may ask for it to be tested at a different certified laboratory within 72 hours of being notified.
49 CFR Part 40 (ODAPC) ↗

Substance Abuse Professional (SAP)

The qualified professional who evaluates you after a violation, decides what education or treatment you need to complete, and confirms when you can take a return-to-duty test. The SAP is the decision point for returning to safety-sensitive work, not your employer.
DOT ODAPC — SAP ↗

Substituted specimen

A sample with readings inconsistent with human urine. Like an adulterated specimen, it's treated as a refusal in regulated testing.
49 CFR Part 40 (eCFR) ↗

T

THCA (aka THC-COOH)

The marijuana metabolite that urine drug tests measure. 49 CFR §40.85 lists it under marijuana metabolites, with a screening cutoff of 50 ng/mL and a confirmatory cutoff of 15 ng/mL.
DOT §40.85 ↗

V

Validity testing

The laboratory's separate check on whether the sample itself is genuine, undiluted human urine. It runs alongside the drug test, independently of it.
49 CFR Part 40 (eCFR) ↗

Verified result

A laboratory result that has been through Medical Review Officer review. Until then, there's a laboratory result but no verified one, and nothing should be reported to an employer.
49 CFR Part 40 (ODAPC) ↗