Chemistry & Environmental Dictionary

UN/NA Number


(UN Number, NA Number, DOT Number)

A four digit number representing a particular chemical or group of chemicals. These numbers are assigned by the United Nations (UN Numbers), the U.S. Department of Transportation (NA Numbers), or Transport Canada (NA Numbers). These numbers are commonly used throughout the world to aid in the quick identification of the materials contained within bulk containers (such as rail cars, semi-trailers and intermodal containers).

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