Drug Testing Glossary

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49 CFR Part 40 (Part 40)

The federal regulation setting out how every DOT drug and alcohol test is collected, analysed, reviewed and reported. Every DOT-regulated industry runs testing through it, and an employer cannot vary it.
49 CFR Part 40 (eCFR) ↗

6-Acetylmorphine (6-AM)

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

A

Adulterated specimen

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

Aliquot

A measured portion poured off from your sample for a particular test. One collection yields several aliquots, which is how a laboratory screens, confirms and checks validity without needing you to give more.
HHS Mandatory Guidelines (2026) ↗

Alcohol Testing Form (ATF)

The federal form recording an alcohol test end to end — your identification, the device used, the readings and your signature. The alcohol counterpart to the custody and control form used for urine.
49 CFR Part 40 (eCFR) ↗

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. Worth knowing because it undercuts the assumption that only a positive result has effect.
FMCSA Clearinghouse ↗

B

Benzoylecgonine

The main substance the body makes from cocaine, and what federal confirmation testing actually looks for. Finding it means cocaine was processed by your body — it is not something 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 litres of breath. Federal testing acts on this number rather than on 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. A separate role from the urine collector, with its own training requirements.
49 CFR Part 40 (eCFR) ↗

C

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. A reporting threshold, not a measure of how much was taken.
DOT §40.85 ↗

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 ↗

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 ↗

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) ↗

Cancelled test

A test that failed procedurally — a broken chain of custody, or a flaw that cannot be corrected. It counts as nothing at all: neither a negative you can rely on nor a positive against you.
49 CFR Part 40 (ODAPC) ↗

Control line

The line on a home test that confirms the device worked. If it is missing, the result is invalid however the rest of the device looks — not positive.
FDA — Home use tests ↗

Cross-reactivity

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

Creatinine

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

Consortium/Third-Party Administrator (C/TPA)

An outside company that runs testing programmes on an employer's behalf — random selection, scheduling, record-keeping. Common for small operators who cannot run a programme alone. The employer keeps the legal responsibility either way.
49 CFR Part 40 (eCFR) ↗

D

Dilute specimen

A sample more watery than a genuine specimen would normally be. It is a statement about concentration, not about drugs — a sample can be both dilute and negative. 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 are not observed; the circumstances that justify it are specified in the rules rather than left to a collector's discretion.
49 CFR Part 40 (ODAPC) ↗

Detection window

The span during which a test can still find a substance after use. It is a property of the substance, the specimen type and the cutoff together, not a fixed number — which is why the same person can be positive in urine and negative in saliva on the same day.
FDA — Drugs of abuse tests ↗

Designated Employer Representative (DER)

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

Drug-free workplace program

A voluntary scheme several states run through workers' compensation: an employer that follows the state's testing rules gets a premium discount and certain defences after an accident. It is the reason many employers test at all in states with no general testing law.
Georgia State Board of Workers' Compensation ↗

E

Ethyl glucuronide (EtG)

A minor by-product of alcohol that lingers in urine well after the alcohol itself has gone, which is why it turns up in abstinence monitoring rather than fitness-for-duty testing. It sits outside the federal programme entirely: DOT alcohol testing measures breath or saliva alcohol, not EtG.

Evidential Breath Testing device (EBT)

A breath alcohol instrument approved for results that can carry consequences, as distinct from a screening-only device. Federal programmes require the model to appear on a published conforming products list.
49 CFR Part 40 (eCFR) ↗

Employee Assistance Program (EAP)

An employer-funded, confidential counselling and referral service. Several state programmes expect one to exist alongside testing, and some policies route a first positive here rather than straight to dismissal.
SAMHSA — Drug-Free Workplace ↗

F

Follow-up testing

A plan of unannounced tests you are placed on after returning to duty. The schedule is given to your employer and never to you — it is meant to be unpredictable.
DOT notice (Mar 2026) — SAP ↗

FMCSA Drug and Alcohol Clearinghouse (Clearinghouse)

The federal database recording drug and alcohol programme violations by commercial drivers. Employers query it, so a recorded violation follows the driver rather than staying with one employer.
FMCSA Clearinghouse ↗

G

Gas chromatography–mass spectrometry (GC/MS)

The confirmation method federal programmes rely on. It separates a sample into its components and identifies each one by mass, which is why 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 analyse federal workplace test specimens. As of August 2026, none are certified for oral fluid — only urine.
HHS certified labs (Aug 2026) ↗

I

Initial test

The first, fast, sensitive test run across all samples. It reacts to families of similar compounds, so it flags samples for further work rather than identifying anything specifically. Also called the screening test.
49 CFR Part 40 (eCFR) ↗

Invalid result

A result the laboratory could not produce a usable answer for. It goes through medical review and usually leads to another collection. It is not an accusation.
49 CFR Part 40 (eCFR) ↗

Immunoassay

The antibody-based method used for the first, cheap pass at a sample. It answers "is anything in the region of this drug class present?" rather than "exactly what is present". Anything that flags at this stage has to be confirmed by a different method before it means anything.
FDA — Drugs of abuse tests ↗

L

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

A confirmation method that does the same job as GC/MS but suits compounds that do not survive the heat of gas chromatography — several opioids and cannabis analytes among them. Federal programmes accept it alongside GC/MS.
HHS Mandatory Guidelines (2026) ↗

Limit of detection (LOD)

The smallest amount an instrument can reliably see. It sits below the cutoff, which is why a laboratory can detect a trace and still report the result negative. The cutoff is a reporting decision; the limit of detection is the edge of what the machine can find.
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 rather than the original drug — a marijuana urine test measures THCA, not THC.
DOT §40.85 ↗

N

Non-negative

Laboratory wording for a sample that the initial test flagged and that now needs confirmation. It means nothing has been established yet. Also seen as preliminary positive or presumptive positive.
49 CFR Part 40 (ODAPC) ↗

O

Oral fluid

The saliva specimen collected by a mouth swab. It has authorised federal cutoffs, far lower than urine, but no laboratory is yet certified to analyse it for federal programmes.
HHS certified labs (Aug 2026) ↗

Opiate

A drug derived directly from the opium poppy — morphine and codeine, with heroin made from morphine. 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 read the substance list rather than the label.
DOT §40.85 ↗

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 ↗

Off-duty conduct statute

A state law making 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 falls inside one turns on whether "lawful" means lawful under state law alone or under federal law too — states split on that, and it decides most cases.
Mont. Code Ann. § 39-2-313 ↗

P

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 ↗

Post-accident testing

Testing required after certain accidents. For commercial drivers, always after a fatality; otherwise only where a citation for a moving violation is issued and someone needed immediate off-scene treatment or a vehicle had to be towed.
49 CFR §382.303 ↗

Point-of-collection test (POCT)

A test read where the sample is given rather than at a laboratory — the instant device format. Fast, cheap, and a screen: several states bar permanent employment action on an unconfirmed instant positive, and federal programmes do not accept one as a result at all.
FDA — Home use tests ↗

Presence-based standard

A rule that treats detecting a substance as the thing that matters, regardless of whether you were affected at work. The alternative ties consequences to impairment, or to a causal link with an incident. Which approach a state takes is usually more consequential than its testing procedures.

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

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) ↗

Refusal to test

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

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, behaviour, speech or body odour. Rumour, tips and general performance concerns do not meet the standard.
49 CFR Part 40 (ODAPC) ↗

S

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) ↗

Substituted specimen

A sample with readings inconsistent with human urine. Like adulteration, it is treated as a refusal in regulated testing rather than as a negative result.
49 CFR Part 40 (eCFR) ↗

Safety-sensitive function

The work that federal testing rules attach to. It is 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) ↗

Substance Abuse Professional (SAP)

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

Shy bladder procedure

The defined process when someone cannot produce a sufficient urine sample: a period with fluids, and if still unsuccessful, a medical evaluation to establish whether there is a genuine medical explanation. Not an automatic refusal.
49 CFR Part 40 (ODAPC) ↗

Specific gravity

How dense a sample is compared with water. Read together with creatinine to decide whether urine is dilute, substituted, or normal. Drinking a large amount of water before a test moves both figures at once.
HHS Mandatory Guidelines (2026) ↗

Safety-sensitive (state law)

State statutes use this phrase too, and define it differently from the federal one — some by risk of death, some by serious property or environmental damage, some by leaving it to the employer to decide. Do not carry the federal meaning across a state line.
W. Va. Code §§ 21-3E-2 to 21-3E-16 ↗

T

THCA

The marijuana metabolite that urine drug tests actually measure. Named in 49 CFR §40.85 as 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 examination of whether the sample itself is genuine, undiluted human urine — run alongside, and independently of, the test for drugs.
49 CFR Part 40 (eCFR) ↗

Verified result

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