Navigating the complexities of hazardous materials transportation requires a clear understanding of safety regulations, and at the forefront of these are Department of Transportation (DOT) labels. These labels are critical for identifying and communicating the hazards associated with materials being transported across the United States, ensuring safety for handlers, transporters, and the public. This comprehensive guide delves into the specifics of DOT labeling as outlined in Title 49 CFR Part 172 Subpart E, providing a detailed look at the requirements, exceptions, and specifications for these essential safety markers.
I. General Labeling Requirements (§ 172.400)
The cornerstone of DOT labeling is ensuring that hazardous materials are clearly identified. According to § 172.400, anyone offering or transporting hazardous materials must label packages and containment devices under specific conditions.
When is Labeling Required?
Labeling is mandated for:
- Non-bulk packages: Any package that is not considered a bulk packaging.
- Small Bulk Packagings: Bulk packagings (excluding cargo tanks, portable tanks, and tank cars) with a volumetric capacity less than 18 m3 (640 cubic feet), unless they are placarded as per subpart F of Part 172.
- Small Portable Tanks: Portable tanks with a capacity less than 3785 L (1000 gallons), unless they are placarded according to subpart F.
- Multi-Unit Tank Car Tanks: DOT Specification 106 or 110 multi-unit tank car tanks, unless placarded under subpart F.
- Small Overpacks and Freight Containers: Overpacks, freight containers, or unit load devices less than 18 m3 (640 cubic feet) containing labeled packages, unless they are placarded or marked as per § 172.512.
Hazard Class and Labeling
The requirement for labeling is triggered when a material meets the definition of one or more hazard classes. Column 6 of the § 172.101 Hazardous Materials Table dictates the necessary labels for each listed material. The following table summarizes the relationship between hazard classes and their corresponding labels:
Table 1: Hazard Class to Label Name and Design
| Hazard Class or Division | Label Name | Label Design or Section Reference |
|---|---|---|
| 1.1 | EXPLOSIVES 1.1 | 172.411 |
| 1.2 | EXPLOSIVES 1.2 | 172.411 |
| 1.3 | EXPLOSIVES 1.3 | 172.411 |
| 1.4 | EXPLOSIVES 1.4 | 172.411 |
| 1.5 | EXPLOSIVES 1.5 | 172.411 |
| 1.6 | EXPLOSIVES 1.6 | 172.411 |
| 2.1 | FLAMMABLE GAS | 172.417 |
| 2.2 | NON-FLAMMABLE GAS | 172.415 |
| 2.3 | POISON GAS | 172.416 |
| 3 Flammable Liquid (Combustible liquid) | FLAMMABLE LIQUID | 172.419 |
| 4.1 | FLAMMABLE SOLID | 172.420 |
| 4.2 | SPONTANEOUSLY COMBUSTIBLE | 172.422 |
| 4.3 | DANGEROUS WHEN WET | 172.423 |
| 5.1 | OXIDIZER | 172.426 |
| 5.2 | ORGANIC PEROXIDE | 172.427 |
| 6.1 (material poisonous by inhalation (see § 171.8)) | POISON INHALATION HAZARD | 172.429 |
| 6.1 (other than a material poisonous by inhalation) | POISON | 172.430 |
| 6.1 (inhalation hazard, Zone A or B) | POISON INHALATION HAZARD | 172.429 |
| 6.1 (other than inhalation hazard, Zone A or B) | POISON | 172.430 |
| 6.2 | INFECTIOUS SUBSTANCE | 172.432 |
| 7 (see § 172.403) | RADIOACTIVE WHITE-I | 172.436 |
| 7 | RADIOACTIVE YELLOW-II | 172.438 |
| 7 | RADIOACTIVE YELLOW-III | 172.440 |
| 7 (fissile radioactive material; see § 172.402) | FISSILE | 172.441 |
| 7 (empty packages, see § 173.428 of this subchapter) | EMPTY | 172.450 |
| 8 | CORROSIVE | 172.442 |
| 9 | CLASS 9 | 172.446 |
II. Exceptions from Labeling (§ 172.400a)
While labeling is broadly required, § 172.400a outlines specific exceptions where labels are not necessary. These exceptions are designed to reduce redundancy or are applicable to specific shipping scenarios.
Common Labeling Exceptions:
- Certain Cylinders and Dewar Flasks: Dewar flasks meeting § 173.320 requirements or cylinders containing Division 2.1, 2.2, or 2.3 materials, if marked according to CGA C-7, Appendix A. However, overpacks containing these items still require labeling.
- Military Explosives: Specific shipments of military explosives by or for the DOD under certain conditions, such as full load shipments loaded/unloaded by shipper/DOD, or unitized shipments by vessel chartered to DOD with at least one label per unit.
- DOD Supervised Shipments: Packages of non-ammunition hazardous materials supervised and escorted by DOD personnel in a separate vehicle.
- Permanently Mounted Cylinders: Compressed gas cylinders permanently mounted on transport vehicles.
- Placarded Freight Containers: Freight containers, aircraft unit load devices, or portable tanks placarded as per subpart F, or conforming to § 172.512(a)(3) or (b)(3).
- Visible Labels in Overpacks: Overpacks or unit load devices where labels for each hazardous material inside are visible.
- Low Specific Activity Radioactive Material: Packages of low specific activity radioactive material and surface contaminated objects transported under § 173.427(a)(6)(vi).
- Toy Caps: Packages containing toy caps classified as “UN0349, Articles, explosive, n.o.s. (Toy caps), 1.4S” or “NA0337, Toy caps, 1.4S” under special provision 382 of § 172.102(c)(1).
- Small and Limited Quantities: Certain exceptions for small quantities and limited quantities as detailed in Part 173.
- Specific Subsidiary Hazard Exceptions:
- Division 6.1 subsidiary labels are not needed for Class 8 materials if toxicity is solely due to tissue corrosion, not systemic poisoning.
- Division 4.1 subsidiary labels are not needed on packages with Division 4.2 labels.
- Poisonous by Inhalation Exception: Under conditions in § 171.23(b)(10), packages of inhalation hazards in closed transport vehicles or freight containers may be excepted from POISON INHALATION HAZARD or POISON GAS labels/placards.
III. Prohibited Labeling (§ 172.401)
To prevent confusion and ensure the integrity of hazard communication, § 172.401 prohibits the use of labels unless specific conditions are met.
Restrictions on Labeling:
- Accurate Representation: Packages must not bear labels unless they contain a hazardous material, and the label must accurately represent a hazard of that material.
- No Conflicting Labels: Markings or labels that could be confused with or conflict with DOT prescribed labels are prohibited.
Exceptions to Prohibited Labeling:
The restrictions do not apply to packages labeled in compliance with:
- UN Recommendations
- IMDG Code (International Maritime Dangerous Goods Code)
- ICAO Technical Instructions (International Civil Aviation Organization)
- TDG Regulations (Transport Dangerous Goods Regulations – Canada)
- Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
Additionally, the prohibition does not apply to packaging that is:
- Unused or cleaned and purged of all residue.
- Transported in a manner where the packaging is not visible during transportation.
- Loaded and unloaded by the shipper or consignee.
IV. Additional Labeling Requirements (§ 172.402)
Beyond primary hazard labels, certain situations necessitate additional or subsidiary labels as per § 172.402.
Subsidiary Hazard Labels
Packages must bear both primary and subsidiary hazard labels as specified in Column 6 of the § 172.101 table. For materials other than Class 1 or 2, subsidiary hazard labels are required according to the following table:
Subsidiary Hazard Labels Table
| Subsidiary Hazard Level (Packing Group) | Subsidiary Hazard (Class or Division) |
|---|---|
| 3 | |
| I | X |
| II | X |
| III | * |
X—Required for all modes.
—Required for all modes, except for a material with a flash point at or above 38 °C (100 °F) transported by rail or highway.
**—Reserved
***—Impossible as subsidiary hazard.
Other Additional Labeling Requirements:
- Hazard Class Display: The appropriate hazard class or division number must be displayed in the lower corner of both primary and subsidiary hazard labels.
- Cargo Aircraft Only Label: Packages intended for cargo aircraft only must bear the CARGO AIRCRAFT ONLY label (§ 172.448).
- Class 7 (Radioactive) Materials: Must be labeled for Class 7 hazards and any additional hazards, with exceptions under § 173.4, § 173.4a, or § 173.4b for subsidiary hazard labels in certain conditions. Fissile materials require two FISSILE labels (§ 172.441).
- Class 1 (Explosive) Materials: In addition to the primary explosive label, must also be labeled POISON or POISON INHALATION HAZARD if meeting Division 6.1 Packing Groups I or II criteria, and Class 7 labels if applicable.
- Division 2.2 Materials: Must be labeled OXIDIZER if also meeting the definition of an oxidizing gas.
- Division 2.3 Materials: Require additional labels if they meet criteria for:
- Division 2.1: Flammable Gas label
- Division 5.1: Oxidizer label
- Class 8: Corrosive label
V. Class 7 (Radioactive) Material Labeling (§ 172.403)
Radioactive materials have specific labeling protocols outlined in § 172.403, based on radiation levels and transport index.
Label Categories for Radioactive Materials:
The label category depends on the radiation level at the package surface and the transport index (TI). RADIOACTIVE WHITE-I is the lowest, and RADIOACTIVE YELLOW-III is the highest category. The highest category determined by either surface radiation level or TI dictates the label.
Table 2: Radioactive Material Label Categories
| Transport Index | Maximum Radiation Level at any point on the external surface | Label Category¹ |
|---|---|---|
| 0² | Less than or equal to 0.005 mSv/h (0.5 mrem/h) | WHITE-I. |
| More than 0 but not more than 1 | Greater than 0.005 mSv/h (0.5 mrem/h) but less than or equal to 0.5 mSv/h (50 mrem/h) | YELLOW-II. |
| More than 1 but not more than 10 | Greater than 0.5 mSv/h (50 mrem/h) but less than or equal to 2 mSv/h (200 mrem/h) | YELLOW-III. |
| More than 10 | Greater than 2 mSv/h (200 mrem/h) but less than or equal to 10 mSv/h (1,000 mrem/h) | YELLOW-III (Must be shipped under exclusive use provisions; see 173.441(b) of this subchapter). |
¹ Any package containing a “highway route controlled quantity” (§ 173.403 of this subchapter) must be labeled as RADIOACTIVE YELLOW-III.
² If the measured TI is not greater than 0.05, the value may be considered to be zero.
Additional Requirements for Radioactive Labels:
- EMPTY Label: For empty radioactive material packages, see § 173.428(e).
- FISSILE Label: Packages requiring a FISSILE label (§ 172.402) must display the criticality safety index (CSI). Overpacks must show the sum of CSIs for all contained packages.
- Label Placement: Two RADIOACTIVE labels are required on opposite sides of the package (§ 172.406(e)(3) for freight containers).
- Label Information: Blank spaces on RADIOACTIVE labels must be filled with:
- Contents: Radionuclide names (or “LSA-I” for LSA-I material).
- Activity: Maximum activity in SI units (e.g., Becquerels) and optionally in customary units (e.g., Curies). For certain isotopes, mass can be used instead of or in addition to activity.
- Transport Index: As defined in § 173.403.
- Overpacks: Overpacks must be labeled similarly, with aggregated content, activity, and transport index information. The overpack’s label category determines vehicle placarding, not individual package labels.
VI. Labels for Mixed and Consolidated Packaging (§ 172.404)
Handling packages with multiple hazardous materials or consolidating packages requires specific labeling approaches under § 172.404.
Mixed Packaging:
When compatible hazardous materials of different classes are packed together, each hazard class must be represented by a label on the packaging, outside container, or overpack.
Consolidated Packaging:
For overpacks containing multiple packages of compatible hazardous materials, labels for each class are required unless the individual package labels are visible from the outside.
Consolidation Bins (Motor Carrier Specific):
Under specific conditions for single motor carrier use, consolidation bins up to 64 cubic feet do not require external labeling if:
- Bins are reusable and made of specified materials.
- Inner packages are correctly labeled.
- Materials are compatible as per § 177.848.
- Handling is by a single motor carrier employee.
- Packages are secured to prevent shifting.
- Bins are tagged or marked with each hazard class inside.
- Bins are properly blocked and braced in the vehicle.
- Transport is by a single motor carrier or on railcars with such vehicles.
VII. Authorized Label Modifications (§ 172.405)
Flexibility in label design is permitted under § 172.405 for certain hazard classes and specific materials.
Permissible Label Modifications:
- Hazard Text Omission: For Classes 1, 2, 3, 4, 5, 6, and 8, text indicating the hazard (e.g., FLAMMABLE LIQUID) is optional on primary or subsidiary labels.
- Oxygen Label: For packages containing Oxygen (compressed or refrigerated liquid), a modified OXIDIZER label displaying “OXYGEN” and class number “2” can replace both NON-FLAMMABLE GAS and OXIDIZER labels. The word “OXYGEN” is mandatory on this modified label.
- Packing Group III Poison Label: For Division 6.1, Packing Group III materials, the POISON label can show “PG III” instead of “POISON” or “TOXIC” below the midline. Refer to § 172.313(d) for additional marking considerations.
VIII. Placement of Labels (§ 172.406)
Proper placement of labels ensures visibility and effectiveness. § 172.406 details these requirements.
General Placement Rules:
- Surface and Location: Labels must be on a surface other than the bottom of the package, ideally on the same surface and near the proper shipping name.
- Aircraft Transportation: For air transport, all labels must be on one side of the package. For cylindrical packages, labels must not overlap. Radioactive material cylinders requiring two labels should have them opposite each other, avoiding overlap. If overlap is unavoidable due to size, one non-overlapping label is acceptable.
- No Duplicate Labeling: Generally, duplicate labeling is not needed unless specifically required.
Exceptions for Label Placement:
Labels can be placed on securely affixed tags or by other suitable means for:
- Packages without radioactive material smaller than label size.
- Cylinders.
- Packages with irregular surfaces where labels cannot adhere properly.
Multiple Labels:
Primary and subsidiary hazard labels must be placed next to each other, ideally within 150 mm (6 inches).
Contrast and Visibility:
Labels must contrast with the background color or have a dotted or solid line outer border to enhance visibility. Labels must be clearly visible and not obscured by other markings or attachments.
Duplicate Labeling Requirements:
Duplicate labels are required on at least two sides (excluding the bottom) for:
- Packages/overpacks of 1.8 m3 (64 cubic feet) or more.
- Non-bulk packages with radioactive material.
- DOT 106 or 110 multi-unit tank car tanks (on each end).
- Portable tanks less than 3,785 L (1000 gallons).
- Freight containers/aircraft unit load devices of 1.8 m3 to 18 m3 (closure area).
- IBCs of 1.8 m3 (64 cubic feet) or more.
IX. Label Specifications (§ 172.407)
Label integrity and design are crucial for quick hazard recognition. § 172.407 specifies these criteria.
Label Durability:
Labels must be durable and weather-resistant, capable of withstanding a 30-day exposure to typical transportation conditions without significant deterioration or color change.
Design and Size:
- Design Consistency: Except for size and color, labels must adhere to the designs shown in §§ 172.411 through 172.448. The dotted line border is not part of the specification unless used to enhance visibility against the background color.
- Size Specifications: Diamond labels must be at least 100 mm (3.9 inches) on each side, with a 5 mm (.2 inches) inner border. Dimensions can be reduced proportionally if package size necessitates, provided symbols and elements remain visible. Hazard class/division numbers must be 6.3 mm to 12.7 mm (0.25 to 0.5 inches). Text indicating hazard must be at least 7.6 mm (0.3 inches), with specific sizes for “Spontaneously” and “When Wet” at 5.1 mm (0.2 inches). Symbols must be proportionate.
Color Specifications:
- Background Colors: Must conform to §§ 172.411 through 172.448.
- Symbol, Text, and Border Colors: Generally black, except white may be used on green, red, or blue backgrounds, and must be used for CORROSIVE label text and class number. White may be used for the ORGANIC PEROXIDE symbol and inner border.
- Fade Resistance: Black and any color must withstand a 72-hour fadeometer test.
- Color Tolerances: Colors must fall within specified tolerances on color charts in appendix A to Part 172 or, for labels printed on packaging, as per table 3 in appendix A.
- PANTONE® Standards: Specific PANTONE® colors are recommended for Red, Orange, Yellow, Green, Blue, and Purple. Spectrophotometer use is advised to ensure color accuracy for opaque coatings or direct printing.
- Color Extent: Specified label color must extend to the edge, except for CORROSIVE, RADIOACTIVE YELLOW-II, and RADIOACTIVE YELLOW-III labels where color extends only to the inner border.
Form Identification:
Labels may include form identification information outside the inner border in no more than 10-point type.
International Standards Exception:
Labels conforming to UN Recommendations, ICAO, IMDG, or Transport Canada TDG Regulations are acceptable replacements, except for materials poisonous by inhalation.
Trefoil Symbol:
The trefoil symbol on RADIOACTIVE labels must meet specifications in appendix B of Part 172.
X. Specific Label Designs (§§ 172.411 – 172.450)
Sections 172.411 through 172.450 detail the design specifications for each type of DOT hazard label, including:
-
§ 172.411: EXPLOSIVE 1.1, 1.2, 1.3, 1.4, 1.5 and 1.6 labels, and EXPLOSIVE Subsidiary label.
EXPLOSIVE 1.1, 1.2, 1.3 Labels
EXPLOSIVE 1.4 Label
EXPLOSIVE 1.5 Label
EXPLOSIVE 1.6 Label
EXPLOSIVE Subsidiary label -
§ 172.415: NON-FLAMMABLE GAS label.
NON-FLAMMABLE GAS label -
§ 172.416: POISON GAS label.
POISON GAS label -
§ 172.417: FLAMMABLE GAS label.
FLAMMABLE GAS label -
§ 172.419: FLAMMABLE LIQUID label.
FLAMMABLE LIQUID label -
§ 172.420: FLAMMABLE SOLID label.
FLAMMABLE SOLID label -
§ 172.422: SPONTANEOUSLY COMBUSTIBLE label.
SPONTANEOUSLY COMBUSTIBLE label -
§ 172.423: DANGEROUS WHEN WET label.
DANGEROUS WHEN WET label -
§ 172.426: OXIDIZER label.
OXIDIZER label -
§ 172.427: ORGANIC PEROXIDE label.
ORGANIC PEROXIDE label -
§ 172.429: POISON INHALATION HAZARD label.
POISON INHALATION HAZARD label -
§ 172.430: POISON label.
POISON label -
§ 172.432: INFECTIOUS SUBSTANCE label.
INFECTIOUS SUBSTANCE label -
§ 172.436: RADIOACTIVE WHITE-I label.
RADIOACTIVE WHITE-I label -
§ 172.438: RADIOACTIVE YELLOW-II label.
RADIOACTIVE YELLOW-II label -
§ 172.440: RADIOACTIVE YELLOW-III label.
RADIOACTIVE YELLOW-III label -
§ 172.441: FISSILE label.
FISSILE label -
§ 172.442: CORROSIVE label.
CORROSIVE label -
§ 172.446: CLASS 9 label.
CLASS 9 label -
§ 172.447: LITHIUM BATTERY label.
LITHIUM BATTERY label -
§ 172.448: CARGO AIRCRAFT ONLY label.
CARGO AIRCRAFT ONLY label -
§ 172.450: EMPTY label.
EMPTY label
These sections provide visual examples and specific color and symbol requirements for each DOT hazard label, ensuring standardized communication of risks in transportation.
Conclusion
DOT labels are an indispensable part of hazardous materials transportation safety. Compliance with labeling regulations is not just a legal requirement but a critical component of ensuring safety and preventing accidents. This guide provides a detailed overview of the labeling requirements, exceptions, and specifications as defined in 49 CFR Part 172 Subpart E, serving as a vital resource for anyone involved in the shipping and handling of hazardous materials. Understanding and correctly applying these regulations are paramount for maintaining a safe and efficient transportation system.
