Trade Secret Registry Number
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UN/NA numbers are required for the shipment of hazardous materials. You have probably seen placards (such as the one on the right) that bear a UN/NA number on railway cars, trucks, shipping containers etc.
UN numbers are assigned by a committee of the United Nations, the Economic and Social Council (ECOSOC) Committee of Experts (COE) on the Transport of Dangerous Goods which issues "Recommendations on the Transport of Dangerous Goods" (also called "the Orange Book").
UN Recommendations are not regulations, but are recommendations addressing the international transport of dangerous goods by sea, air, road, rail and inland waterways. These recommendations are reviewed, amended and updated biennially (every second year) by the UN COE and are distributed to nations throughout the world.
These recommendations serve as the basis for national, regional, and international transport regulations such as those prepared by the International Maritime Organization (IMO) and the International Civil Aviation Organization (ICAO). The UN Recommendations are also used as a basis for the development of regional (e.g., NAFTA and European Road and Rail regulations) and national transport regulations, including the U.S. Hazardous Materials Regulations (see our entry on DOT).
The UN Recommendations on the Transport of Dangerous Goods addresses the following areas:
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UN numbers uniquely identify only a very small number of chemicals or families of chemicals (less than 10,000), unlike CAS Registry Numbers, which are assigned to each of the 159,000,000+ unique chemical compounds that have been discovered. UN/NA numbers are very useful for shippers and emergency first-responders, but are not particularly applicable to employees occupationally exposed to the materials.
Keep informed about workplace hazards with proper labeling techniques and safety posters available from Safety Emporium.
UN/NA numbers are not required elements by OSHA on an SDS, although many sheets have them to simplify shipping requirements.
DOT's 2020 Emergency Response Guide Book is indexed by "ID Numbers" which are actually the UN/NA number. Be careful not to confuse the ID number (UN/NA number) with the Guide number (the page that tells you about the properties and hazards). For example, the UN/NA number for ammonia is 1005, but the hazards are discussed in Guide entry 125.
The Guide is a free download and is on-line searchable. Ideally, a hard copy of the Guide should be every kept on any vehicle, train, boat or aircraft that transports hazardous materials as well as every emergency rescue vehicle. It is available as a FREE app on the Apple App Store as well as on Google Play.
See also: CAS number, EINECS number, The SDS FAQ, Labeling provisions of the OSHA Hazard Communication Standard.
Additional definitions from Google and OneLook.
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