UN numbers (United Nations numbers) are four-digit numbers that identify hazardous materials, and articles (such as explosives, Flammable Liquids to oxidizing solid or toxic liquids, etc.) in the framework of international transport. Some hazardous substances have their own UN numbers (e.g. acrylamide has UN 2074), while sometimes groups of chemicals or products with similar properties receive a common UN number (e.g. flammable liquids, not otherwise specified, have UN1993). A chemical in its solid state may receive a different UN number than the liquid phase if their hazardous properties differ significantly; substances with different levels of purity (or concentration in solution) may also receive different UN numbers.
UN numbers range from UN 0004 to about UN 3534 (UN 0001 – UN 0003 no longer exist) and are assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods. They are published as part of their Recommendations on the Transport of Dangerous Goods, also known as the Orange Book. These recommendations are adopted by the regulatory organization responsible for the different modes of transport.
There is no UN number allocated to non-hazardous substances. These will simply not have a UN number.
For more details, see Lists of UN numbers.
NA numbers (North America), are issued by the United States Department of Transportation and are identical to UN numbers, except that some substances without a UN number may have an NA number. These additional NA numbers use the range NA 9000 - NA 9279. There are some exceptions, for example NA 2212 is all asbestos with UN 2212 limited to Asbestos, amphibole amosite, tremolite, actinolite, anthophyllite, or crocidolite. Another exception, NA 3334, is self-defense spray, non-pressurized while UN 3334 is aviation regulated liquid, not otherwise specified. For the complete list, see NA/UN exceptions.
For more details see List of NA numbers.
ID numbers are a third type of identification number used for hazardous substances. Substances with an ID number are associated with proper shipping names recognized by the ICAO Technical Instructions. There is only one substance that currently has such a number: ID 8000, Consumer commodity. This substance does not have a UN or NA number, and is classed as a Class 9 hazardous material.
Associated with each UN number is a hazard identifier, which encodes the general hazard class and subdivision (and, in the case of explosives, their compatibility group). If a substance poses several dangers, then subsidiary risk identifiers may be specified. It is not possible to deduce the hazard class(es) of a substance from its UN number: they have to be looked up in a table.
- "Title 49 - Part 173 - Subtitle B - Chapter I - Subchapter C - Part 172 - Subpart B". eCFR - Code of Federal Regulations. U.S. Government Publishing Office. Retrieved 2017-09-27.
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- Search UN/NA-numbers HazMat Database based on US-CFR 49
- United Nations Committee of Experts on the Transport of Dangerous Goods
- UN Recommendations on the Transport of Dangerous Goods. Part 2 defines the hazard classes and their divisions and Part 3 contains a complete list of all UN numbers and their hazard identifiers.
- The Emergency Response Guidebook from the U.S. Department of Transportation contains a list of all assigned NA numbers along with recommended emergency procedures.
- UN and NA Numbers. Site provides bill of lading shipping descriptions for transportation in the U.S.