Subsidiary hazards

Scope

The shipper is responsible for properly classifying a hazardous material and identifying any subsidiary hazards, along with applying/providing the appropriate labels and placards.

Regulatory citations

• 49 CFR 172.402 — Additional labeling requirements
• 49 CFR 172.505 — Placarding for subsidiary hazards

Key definitions

• Primary hazard. The hazard class of a material as assigned in the 49 CFR 172.101 hazardous materials table.
• Subsidiary hazard. A hazard of a material other than the primary hazard.

Summary of requirements

The primary hazard of a material is shown in Column 3 of the Hazardous Materials Table (HMT). For the classification of materials not listed in the HMT, 173.2a, “Classification of a material having more than one hazard,” should be consulted to determine the primary hazard.

A subsidiary hazard is a hazard of a material other than the primary hazard.

Labeling. For materials listed in the HMT, paragraph 172.101(g) states “Column 6 specifies codes which represent the hazard warning labels required for a package. The first code is indicative of the primary hazard of the material, additional label codes are indicative of subsidiary hazards.”

Placarding. Each transport vehicle, freight container, portable tank, unit load device, or rail car that contains a poisonous material (subject to the “Poison Inhalation Hazard” shipping description in 172.203(m)) must be placarded with a POISON INHALATION HAZARD or POISON GAS placard, as appropriate, on each side and each end, in addition to any other placard required for that material in 49 CFR 172.504. Duplication of the POISON INHALATION HAZARD or POISON GAS placard is not required.

In addition to the RADIOACTIVE placard which may be required, each transport vehicle, portable tank, or freight container that contains 454 kg (1,001 pounds) or more gross weight of non-fissile, fissile-excepted, or fissile uranium hexafluoride must be placarded with a CORROSIVE placard and a POISON placard on each side and each end.

Each transport vehicle, portable tank, freight container, or unit load device that contains a material which has a subsidiary hazard of being dangerous when wet must be placarded with DANGEROUS WHEN WET placards, on each side and each end, in addition to the placards required by 49 CFR 172.504.

Hazardous materials that possess secondary hazards may exhibit subsidiary placards that correspond to the placards described, even when not required.