You can help prevent illness and injury by reading the warning label for each hazardous substance you use. If you have any questions after reading the warning label, check the MSDS. The MSDS is probably the most detailed source of information for the hazardous substance you are using.
You may see a warning label on a container or box of containers, such as a case of chemical jugs. These labels provide the most important information you need to know about the substance you are handling.
Hazard ratings—from 0 to 4, with 4 being the most hazardous—are used for 3 categories: Health, Flammability, and Reactivity. For example, if the substance has a low risk of flammability, a “1” may appear in the Flammability section. The Special Notice category shows other important hazards to be aware of.