Shipping Unidentified Hazardous Materials

Posted on 5/19/2022 by Roger Marks and Bob Clarke, CDGP

Recently, the United States Congress held a hearing about sightings of unidentified flying objects. Some of these flying objects are hard to classify because authorities don’t have much information to go on.

The same is true for what we’ll call “UHMs”—Unidentified Hazardous Materials. If you haven’t had a close encounter with a UHM yet, give it time. Someday you may be confronted with a material or product for which you have no conclusive proof of the chemical makeup, properties, or potential hazards.

Shippers need that information to properly classify, name, package, mark, label, and document a shipment. The good news is that, for most materials, shippers can follow slightly less restrictive requirements to ship a small quantity of a sample to a lab for testing purposes.

Here’s how it works.

Classification and Naming for Hazmat Samples

Though we don’t know the material’s exact properties, we know it is potentially hazardous and subject to regulation. To ship a sample for testing, we must use the information and knowledge available to determine a tentative proper shipping name, hazard class, ID number, and packing group (PG).

If we think our material is a flammable liquid, but don’t know the flash point or boiling point, we may assign Hazard Class 3 and use the Proper Shipping Name “Flammable liquid n.o.s.”

The Hazmat Table at 49 CFR 172.101 lists three entries for flammable liquid n.o.s.—one each for PG I, II, and III. The shipper can choose the PG they believe best applies to the material based on the limited information available.

The word “Sample” must be added in front of (or after) the Proper Shipping Name, unless the word is already part of the proper shipping name.

  • Sample Flammable liquid n.o.s.; or
  • Flammable liquid n.o.s. Sample

Because the shipper may not know the chemical makeup of the material, the technical name(s) typically required in parenthesis after a generic (G) shipping name are not required in this situation (49 CFR 172.101(c)(11)(iv)(B)).

Important: Additional requirements apply to the transport of samples of self-reactive materials, organic peroxides, explosives, or lighters. In addition, materials that are forbidden from transportation may not be shipped as samples using these reliefs.

Air and vessel shipments: The requirements outlined in this article apply to shipments of hazardous materials by ground. Additional requirements apply to hazmat samples shipped by air and vessel, including stricter classification criteria and shipping paper requirements. For training and resources to comply with the latest IATA DGR and IMDG Code standards, visit

Packaging Hazmat Samples

To package a sample of an unidentified hazardous material, shippers must comply with the general packaging requirements, special provisions, and applicable packaging authorizations in 49 CFR Part 173.

From the 172.101 Hazmat Table, shippers may choose to follow the authorized packaging instructions for limited quantities and exceptions (Column 8A) or non-bulk shipments (8B).

Combination packaging must be used. Combination packagings include inner receptacles inside of an outer packaging (e.g., plastic bottles in a fiberboard box).

The quantity of material is limited to a net mass of 2.5 kg (5.5 lbs). Size limits for the inner receptacles vary based on the packaging instructions the shipper chooses to follow.

Shipping Papers for Hazmat Samples

Shipping papers may or may not be required, depending on which packaging instructions the shipper chooses. Generally, shipping papers are not required for limited or excepted quantity shipments.

Shipping papers are required for fully regulated shipments (i.e., those prepared according to Column 8B).

All required elements of the basic description must be included on the shipper papers—UN number, proper shipping name, Hazard Class, packing group, and the type and quantity of packaging used.

Like with the proper shipping name marked on the package, the word “Sample” should precede the name on the shipping papers.


UN1993, SAMPLE Flammable liquid n.o.s., 3, II, 1 Fiberboard box X 3 lbs.

Using the Materials of Trade Exceptions

The Materials of Trade exceptions in 49 CFR 173.6 allows a shipper to transport small amounts of hazardous materials in a personal or company vehicle.

This valuable exception could be used to transport a sample for testing purposes, provided some basic quantity limits, packaging rules, and hazard communication requirements are followed.

Learn more: Transporting Materials of Trade Training

The Last Word

Sending a sample to a lab for analysis is a great way—and sometimes the only reasonable way—to acquire the information needed to properly classify a hazardous material. While the regulations offer slightly relaxed requirements for these shipments of unidentified hazardous materials, the shipper must ensure the material is shipped safely and in compliance with all applicable rules. 

Using the DOT reliefs for hazmat samples spelled out in the HMR, shippers can send their samples where many samples have gone before—to a lab for testing. 

Instructor-led DOT Hazmat Training

Join a workshop or webinar for live, instructor-led training to ship hazardous materials in full compliance with the latest US and international regulations for ground, air, and vessel shippers. 

The two-day Hazmat Ground Shipper Certification (DOT) Workshop comes to San Diego, Denver, Nashville, Orlando, Dallas, and Houston this year,  

Upcoming Webinars

Recurrent Hazmat Ground Shipper Certification (DOT)      June 6
Hazmat Air Shipper Certification (IATA) June 7
Hazmat Vessel Shipper Certification (IMDG) June 8
Hazmat Ground Shipper Certification (DOT)  June 13–14  
Shipping Lithium Batteries June 28

Prefer to train at your own pace? Choose interactive, mobile-ready online training to learn what you need to know to ship hazardous materials, manage hazardous waste, prepare for emergencies, and comply with OSHA workplace safety regulations. Visit

Tags: DOT compliance, hazardous materials, hazmat samples, shipping hazmat samples

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