DOT saliva drug testing: oral fluid under 49 CFR Part 40

DOT saliva drug testing has been allowed under 49 CFR Part 40 since June 1, 2023. But no DOT-regulated employer can actually use it yet, because the rule needs at least two HHS-listed oral fluid laboratories, and as of the HHS list dated November 2, 2026, there are none.

So today, every DOT drug test is a urine test. This page explains the oral fluid rules that are already written, what has to happen before they switch on, and what employers should do in the meantime.

This page summarizes federal rules in plain language. It is not legal advice.

Where oral fluid testing stands

• Authorized: DOT's final rule of May 2, 2023 (88 FR 27596), in effect June 1, 2023, added oral fluid "as an additional methodology." That background is restated in DOT's May 11, 2026 rule (91 FR 25507).
• Blocked: for an employer to use oral fluid, 49 CFR 40.67(g)(5) requires at least two oral fluid drug testing laboratories approved by HHS. One lab tests the primary specimen; a different one tests the split if the employee asks.
• Status: the HHS laboratory lists dated September 30, 2026 (91 FR 61854) and November 2, 2026 (91 FR 68964) both state that no laboratory is yet approved to test oral fluid specimens.

Labs also need HHS approval "for each specimen testing methodology" they run for DOT (40.81(a)). A lab approved for urine is not automatically approved for oral fluid.

When oral fluid becomes available, who decides urine or saliva?

The employer, in nearly every case. DOT's 2026 rule says oral fluid is "an alternate methodology, not as a replacement for urine," and that outside a few observed-collection situations "an employer may choose whether to conduct a urine or an oral fluid test." DOT left the choice to employers because the two specimen types have different windows of detection.

The employer passes that choice to the collector: specimen type is one of the items an employer must give the collector for each test (40.14(k)).

Three conditions all have to be met at the collection site: two HHS-listed oral fluid labs exist, a qualified oral fluid collector is there, and a conforming collection device is available (40.67(g)(5)).

DOT drug testing procedures for an oral fluid collection

The procedure is already in the rule, in 40.72 through 40.74.

Before the collection (40.72):

1. The collector asks the employee to open their mouth and checks for anything that could interfere, such as candy, gum, food or tobacco.
2. If something is removed, the saliva looks abnormal, or the employee says they have dry mouth, the collector gives up to 8 ounces of water to rinse and waits 10 minutes.
3. Otherwise there is still a 10-minute wait before collection, used to review the device instructions and complete the custody form.
4. The collection device must be unused, sealed, and within its expiration date, and it is opened in front of the employee.

During the collection (40.73): the collector stays present with visual contact the whole time, the employee positions the device under observation, and the collector confirms a sufficient volume by watching the device's volume indicator. No one else may watch except a DOT agency representative.

After the collection (40.74): at least 1 mL of undiluted oral fluid goes into Bottle A and at least 1 mL into Bottle B. Tamper-evident seals go on in front of the employee, who initials them.

Every oral fluid collection counts as observed. Part 40 defines an oral fluid specimen as "a direct observation collection for all purposes of this part" (40.3), because it happens in front of the collector.

What if the employee can't produce enough saliva?

A DOT oral fluid test needs 2 mL in a single sampling (40.193(a)). If an employee cannot provide it after 15 minutes with the device, and says they could after drinking, the collector offers up to 8 ounces and waits 10 more minutes. The full window is one hour from the first unsuccessful attempt (40.193(b)(2)).

The employer can also tell the collector to switch to urine at that point, or from urine to oral fluid, if a qualified collector is available (40.193(a)).

DOT drug testing standards for oral fluid: the cutoffs

Oral fluid tests the same five drug classes as urine, but the cutoffs are much lower. From 49 CFR 40.91, in ng/mL:

Note that oral fluid looks for THC itself, while the urine test looks for the THCA metabolite. Urine cutoffs for comparison: DOT drug test cutoff levels.

Validity testing is different, too. For urine, validity testing is mandatory on every specimen. For oral fluid, the lab may run it when a specimen looks abnormal or interferes with testing (40.92), and may test for a biomarker such as albumin or immunoglobulin G (40.93).

One new fatal flaw. If the collector used an expired device, the lab must reject the specimen (40.83(c)(8)).

Who can collect oral fluid for DOT?

Only a collector trained specifically for it. Under 40.35, an oral fluid collector needs qualification training that includes proficiency on the specific device they will use, then five consecutive error-free mock collections for each device, monitored by a qualified person. Refresher training is due at least every five years.

Collections can take place at a permanent or temporary site, at the work site or remotely, including "a mobile facility (e.g., a van)" (40.47(b)).

Can a Utah employer use saliva tests outside DOT?

Yes, for non-DOT testing. The Utah Drug and Alcohol Testing Act lists saliva as a permitted sample (Utah Code 34-38-2(9)) and lets the employer designate the sample type (34-38-4). That is a company-policy decision, separate from DOT rules.

What to do now

1. Keep using urine for DOT tests. It is the only DOT option until HHS lists two oral fluid labs.
2. Give your collector a standing order on what to do when an observed collection is required. Since June 10, 2026, the rule calls for a directly observed urine collection when oral fluid is not available. Background: what changed for DOT testing in 2026.
3. Watch for the second lab. After HHS notifies a second oral fluid lab, there is an 18-month grace period for employers to keep using observed urine collections while they set up oral fluid (40.67(g)(6)).
4. Watch the HHS proposal. HHS proposed revisions to its oral fluid guidelines on October 29, 2026. Comments are due December 28, 2026.

Quick answers

Is a DOT drug test urine or saliva?

Urine, for now. Oral fluid is allowed by rule but there are no HHS-listed oral fluid labs.

Are DOT saliva tests observed?

Yes. Every oral fluid collection is treated as a direct observation collection (40.3).

Will oral fluid replace urine?

No. DOT describes it as an alternative the employer may choose, not a replacement.

DOT-compliant drug testing today

BBB Mobile DOT Drug Testing collects DOT urine tests on site across Park City, Summit and Wasatch counties and the Salt Lake metro, including post-accident and return-to-duty collections. For company-policy testing, see non-DOT testing. Price a visit with the estimator or call (435) 395-1459.