A UN number (

United Nations The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and security, develop friendly relations among nations, achieve international cooperation, and be a centre for harmoni ...

number) is a four-digit number that identifies

hazardous materials Dangerous goods, abbreviated DG, are substances that when transported are a risk to health, safety, property or the environment. Certain dangerous goods that pose risks even when not being transported are known as hazardous materials ( syllabi ...

, and articles (such as

explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An expl ...

s, flammable liquids,

oxidizer An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxi ...

s, toxic liquids, etc.) in the framework of

international trade International trade is the exchange of capital, goods, and services across international borders or territories because there is a need or want of goods or services. (see: World economy) In most countries, such trade represents a significa ...

and

transport Transport (in British English), or transportation (in American English), is the intentional movement of humans, animals, and goods from one location to another. Modes of transport include air, land ( rail and road), water, cable, pipelin ...

. Some hazardous substances have their own UN numbers (e.g.

acrylamide Acrylamide (or acrylic amide) is an organic compound with the chemical formula CH2=CHC(O)NH2. It is a white odorless solid, soluble in water and several organic solvents. From the chemistry perspective, acrylamide is a vinyl-substituted primar ...

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 UN 1993). A chemical in its

solid Solid is one of the four fundamental states of matter (the others being liquid, gas, and plasma). The molecules in a solid are closely packed together and contain the least amount of kinetic energy. A solid is characterized by structur ...

state may receive a different UN number than the liquid phase if its hazardous properties differ significantly; substances with different levels of purity (or

concentration In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', '' molar concentration'', ''number concentration'', ...

in solution) may also receive different UN numbers.

Hazard identifiers

Associated with each UN number is a hazard identifier, which encodes the general hazard class and subdivision (and, in the case of

explosives An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An expl ...

, their compatibility group). If a substance poses several dangers, then subsidiary

risk In simple terms, risk is the possibility of something bad happening. Risk involves uncertainty about the effects/implications of an activity with respect to something that humans value (such as health, well-being, wealth, property or the environm ...

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.

Range

UN numbers range from UN 0004 to about UN 3548 (UN 0001 – UN 0003 are no longer in use) and are assigned by the

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.

Non-UN identifiers

An NA number (

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...

number) is issued by the

United States Department of Transportation The United States Department of Transportation (USDOT or DOT) is one of the executive departments of the U.S. federal government. It is headed by the secretary of transportation, who reports directly to the President of the United States and ...

and is 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 Asbestos () is a naturally occurring fibrous silicate mineral. There are six types, all of which are composed of long and thin fibrous crystals, each fibre being composed of many microscopic "fibrils" that can be released into the atmosphere b ...

with UN 2212 limited to

Asbestos Asbestos () is a naturally occurring fibrous silicate mineral. There are six types, all of which are composed of long and thin fibrous crystals, each fibre being composed of many microscopic "fibrils" that can be released into the atmosphere b ...

amphibole Amphibole () is a group of inosilicate minerals, forming prism or needlelike crystals, composed of double chain tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures. Its IMA symbol is ...

amosite,

tremolite Tremolite is a member of the amphibole group of silicate minerals with composition: Ca2(Mg5.0-4.5Fe2+0.0-0.5)Si8O22(OH)2. Tremolite forms by metamorphism of sediments rich in dolomite and quartz. Tremolite forms a series with actinolite and fe ...

, actinolite,

anthophyllite Anthophyllite is an orthorhombic amphibole mineral: ☐Mg2Mg5Si8O22(OH)2 (☐ is for a vacancy, a point defect in the crystal structure), magnesium iron inosilicate hydroxide. Anthophyllite is polymorphic with cummingtonite. Some forms of ...

, or

crocidolite Riebeckite is a sodium-rich member of the amphibole group of silicate minerals, chemical formula Na2(Fe2+3Fe3+2)Si8O22(OH)2. It forms a solid solution series with magnesioriebeckite. It crystallizes in the monoclinic system, usually as long prism ...

. Another exception, NA 3334, is self-defense spray, non-pressurized while UN 3334 is

aviation Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' includes airplane, fixed-wing and helicopter, rotary-wing types, morphable wings, wing-less lifting bodies, as well as aerostat, lighter- ...

-regulated liquid, not otherwise specified. For the complete list, see NA/UN exceptions. An ID number is a third type of identification number used for hazardous substances being offered for

Air transport Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' includes fixed-wing and rotary-wing types, morphable wings, wing-less lifting bodies, as well as lighter-than-air craft such as hot air ...

. Substances with an ID number are associated with proper

shipping Freight transport, also referred as ''Freight Forwarding'', is the physical process of transporting commodities and merchandise goods and cargo. The term shipping originally referred to transport by sea but in American English, it has been ...

names recognized by the

ICAO The International Civil Aviation Organization (ICAO, ) is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation, and fosters the planning and development of international a ...

Technical Instructions. ID 8000, Consumer commodity does not have a UN or NA number, and is classed as a Class 9 hazardous material.

References

External links

United Nations Committee of Experts 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. * Th
Emergency Response Guidebook
from the U.S. Department of Transportation contains a list of all assigned NA numbers along with recommended emergency procedures. {{Portal bar, Politics Chemical numbering schemes

Hazard identifiers

Range

Non-UN identifiers

See also

References

External links