Experienced laboratory managers know that there are four basic categories of chemicals: toxic, corrosive, flammable and reactive. However, in our chemical world there are many additional categories and subsets of these main four. We should also keep in mind that many chemicals exhibit a combination of properties and would fall into more than a single class or category. These four properties are the foundation of the NFPA hazard diamond.

At the bottom of the diamond is the white section. This section is used to denote special hazards. NFPA 704, Standard System for the Identification of the Hazards of Materials for Emergency Response,¹ mentions only two approved symbols:

Some organizations and manufacturers use additional symbols to indicate hazards associated with the substance. One example is the Hazardous Materials Emergency Response Guidebook;² a few of these are presented above.

Vince McLeod is an American Board of Industrial Hygiene– certified industrial hygienist and the senior industrial hygienist in the University of Florida’s Environmental Health and Safety Division. He has 22 years of occupational health and safety experience at the University of Florida, and he specializes in conducting exposure assessments and health-hazard evaluations for the university’s 2,200-plus research laboratories.

References

1. Standard System for the Identification of the Hazards of Materials for Emergency Response, National Fire Protection Association, Publication 704. http:// www.nfpa.org/aboutthecodes/AboutTheCodes. asp?DocNum=704
2. Hazardous Materials Emergency Response Guidebook, U.S. Department of Transportation. Washington, D.C. 2008. http://www.fmcsa.dot.gov/safety-security/ hazmat/2004-emergency-response-guidebook.htm