Why is the CAS number important?

Originally, CAS numbers weren’t required to appear on Material Safety Data Sheets. Back then, MSDSs were not formatted in a way that allowed for maximum utility. Once OSHA made the Globally Harmonized System of Classification and Labeling of Chemicals required for all businesses that handled hazardous chemicals, the chemical information requirements changed rapidly. This improvement was much needed for the safety world, it allowed for better communication and improved chemical identification efforts for those that needed it.

June 1, 2015 marked the official change that aligned GHS with OSHA’s Hazard Communication Standard. As a result, not only was the CAS registry number now required to appear in the MSDS, but the whole format of the MSDS changed, starting with changing the name to simply “Safety Data Sheet.” SDSs now have sixteen sections, instead of just eight as the MSDS once had, that incorporate GHS standards regarding labeling and pictograms.

Now, the addition of a CAS number to SDSs has opened up new avenues for more in-depth chemical information. It is common for chemical substances and chemical compounds to have multiple names, and they unfortunately tend to be misspelled by those who aren’t chemists by trade. Just those two details bring up the question of human error in chemical identification, and that can be incredibly dangerous to employees, first responders, and any visitors within the area.

The CAS number prevents those errors by assigning a unique identifier to all chemical substances, and all their various written names. Every SDS needs a CASRN and that number can even be added to a GHS label for extra clarity. Overall, CAS numbers are an important part of hazard identification because it directs the user to the right information needed to stay safe in the presence of hazardous substances.


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