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The De Minimis Exception From the Hazardous Materials Regulations

The De Minimis Exception From the Hazardous Materials Regulations

The transportation in commerce of a hazardous material is usually subject to the Hazardous Material Regulations of the PHMSA/USDOT.  However, the transportation of certain hazardous materials, below specified thresholds, in authorized packaging may receive an exception from full regulation.  And, in some cases, the hazardous material may be fully excepted from regulation under the HMR.  Just such a case of a full exception is the De Minimis Exception, found at 49 CFR 173.4b and summarized below.

If meeting the volume/weight limits and packaged per the requirements of §173.4b, then it will not be a hazardous materials as defined at §171.8 and therefore not subject the hazardous material regulations of the PHMSA/USDOT.


Hazardous materials subject to the De Minimis Exception are limited to Packing Group II and III of the following Hazard Classes and Divisions:

  • Class 3 – Flammable and Combustible Liquids
  • Division 4.1 – Flammable Solids
  • Division 4.2 – Spontaneously Combustible
  • Division 4.3 – Dangerous When Wet
  • Division 5.1 – Organic Peroxide
  • Class 8 – Corrosive Material
  • Class 9 – Miscellaneous

If one of the above authorized materials, the maximum quantity per inner receptacle or article is limited to:

  • One (1) mL (0.03 ounce) for liquids.


  • One (1) g (0.04 ounce) for solids.

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  • Though not clearly specified in §173.4b, three levels of combination packaging are referred to and therefore are required in order to comply with the De Minimis Exception:
    • Inner receptacle
    • Inner packaging
    • Strong outer packaging
  • Removable closures of inner receptacles must be held securely in place with wire, tape, or other positive means.
  • Unless equivalent cushioning and absorbent material is provided for the inner packaging, each inner receptacle must be packaged with sufficient cushioning and absorbent material that:
    • Will not react chemically with the material, and;
    • Is capable of absorbing the entire contents of the receptacle (applies if liquid only).
  • The inner packaging must be securely packed in a strong outer packaging.
  • 49 CFR 173.4b(a)(5) specifies tests the completed package (inner receptacle, absorbents & cushioning, inner packaging, & strong outer packaging) must be capable of withstanding without breakage or leakage from the inner receptacle and without a substantial reduction in the effectiveness of the package.  They include a drop test onto a solid unyielding surface and a compressive load.
  • The tests specified in 49 CFR 173.4b(a)(5) may be performed on a different but identical package.  “That is, all tests need not be performed on the same package.”
  • The completed package can not result in a violation of the Forbidden Materials and Packages restrictions of 49 CFR 173.21.  For example, if the mixing of two or more materials in an inner packaging is likely to cause a dangerous evolution of heat, or flammable or poisonous gases or vapors, or to produce corrosive materials.
  • The aggregate quantity of hazardous material (not the weight of the cushioning, absorbents, and packaging; just the HazMat) does not exceed:
    • 100 g (0.22 lb) for solids.
    • 100 mL (3.38 oz) for liquids.
  • The gross mass of the package (inner receptacle, absorbents & cushioning, inner packaging, strong outer packaging, and the hazardous material) does not exceed 29 kg (64 lb).
  • The package is not opened or otherwise altered while in transportation.  This includes storage during transportation and loading & unloading incidental to transportation.
Transportation by aircraft:

For transportation by aircraft all of the above apply, plus:

  • The HazMat is authorized to be carried aboard passenger-carrying aircraft per Column 9A of the Hazardous Materials Table at 49 CFR 172.101.


  • A HazMat shipped per the De Minimis Exception may not be carried in checked or carry-on baggage.
Non-infectious specimens:

49 CFR 173.4b(b) includes the requirements for shipping De Minimis quantities of non-infectious specimens containing small quantities of Ethanol, Formaldehyde, Alcohols, & Isopropanol.  A full explanation of this part of the De Minimis Exception will have to wait until another article.

HazMat Employee training at 49 CFR 172, Subpart H

HazMat Employee training is required by the USDOT/PHMSA

And that’s it.  If the above requirements are met, than the hazardous material may be offered for transportation and transported in commerce without being subject to the Hazardous Material Regulations.  This may be interpreted to mean that the HazMat Employee training required by 49 CFR 172, Subpart H does not apply, but I don’t think that is true, for two reasons:

  1. Even if ultimately subject to the De Minimis Exception, it begins as a hazardous material, and that’s enough to require HazMat Employee Training for anyone involved in its transportation.
  2. The use of any PHMSA/USDOT exception can be tricky.  One mistake could result in you being out of compliance.  Good training for all personnel involved with the HazMat will help to ensure compliance the De Minimis Exception and the remainder of the HMR.