Chemical Safety Symbols Explained

Safety symbol to be used with corrosive chemicals.

Chemicals are all around us in our day-to-day lives. It is easy to determine the safety of common chemicals once you understand what the basic chemical safety symbols represent. Knowledge of these symbols is critical to understanding what chemicals need to be avoided and what chemicals are not hazardous to your health.

Labeling

The standard chemical hazard label in the United States was designed to inform firefighters of dangers in a situation. The National Fire Protection Agency (NFPA) diamond is divided into four squares: a red "flammable" square at top, a yellow "reactivity" square at the right, a white "special information" square at the bottom and a blue "health" square to the left. The red, yellow and blue squares contain numbers from 0 to 4--with 0 being the most harmless and 4 being the most dangerous. The white section at the bottom of the diamond can hold special instructions if, for example, the chemicals will react with water or if they are oxidizing agents.

Flammable

Flammable chemical diamond

The most common of the chemical diamonds is the "flammable" diamond, which can be found on such objects as fuel tankers and propane tanks. The more flammable the contents of the container bearing the red diamond, the higher the number at the bottom of the diamond. A 0 rating indicates that the chemical is not considered to be flammable. A number 2 means the contents will ignite between 100 and 200 degrees Fahrenheit. A number 4 means the contents can ignite at room temperature and should be considered very flammable.

Biohazards

Biohazard symbol

The Dow company developed the biohazards symbol in 1966 because there was no universal symbol to let people know of a biohazard. This symbol indicates that there are potential biohazards, such as viruses or bacteria, present.

There are four levels of biohazard ratings: level 1 is the least hazardous, having the potential to cause mild illness in humans and animals; 4 warns of bacteria or viruses that are fatal to humans. The biohazard symbol can be found on sharps containers as well as on facilities that deal with biohazards.

Poisons

Poison symbol

The skull and crossbones is probably one of the most famous and universal of all symbols. This symbol signifies that toxic or poisonous chemicals are present. The skull and crossbones can be used in concert with other chemical safety symbols, such as the NFSA diamond or the biohazard symbol for a fuller understanding of what type of toxin is present.

Radioactives

Radioactivity symbol

The symbol for radioactive materials is called the trefoil and is black and yellow. This symbol indicates that there is radioactive material present. According to the United States Nuclear Regulatory Commission, "Radioactive material is defined as any material which has a specific activity greater than 0.002 microcuries per gram." This symbol does not signify the quantity of radioactive material; it indicates that the substance has a specific radioactive concentration.

References

• Northeastern University: NFPA Hazard Rating System
• Harvard University: Symbol Making
• United States Nuclear Regulatory Commission: Radioactive Symbol on Transportation Packages

Resources

• University of Oregon: Safety in the Chemistry Laboratory