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Hazard Communication – A Guide to Symbols

Not following warning labels can be hazardous to your health and the health of those around you. Products containing hazardous chemicals can cause severe injuries or make you sick. Over exposure to some chemicals can also kill you.

Warning labels are worthless if you don’t read them or understand them. OSHA has adopted a standardized system of labeling to help you identify hazards. Make sure you know what to look for and what the symbols mean. 

Note: Hazardous products with these pictograms can be safely worked with if the safety precautions, proper storage, and handling practices are followed. 

Recognize the symbols used on labels

Flame: A gas, liquid or solid product that can burst into flame.
  • Common flammable chemicals include:
  • Gasoline or diesel fuel
  • Solvents
  • Thinners and adhesives
  • Some can catch fire without air, when heated, or coming into contact with water
Flame Over Circle: The ring or “O” stands for oxidizer. Products that are oxidizers are not flammable. Oxidizers cause other materials to burst into flame.
  • Most common oxidizers – Hydrogen Peroxide. Being a strong oxidizer, reactions with H2O2 tend to produce heat and generate oxygen gas(O2). It is that reason why hydrogen peroxide is closely monitored at concentrations above 32% by the U.S government. Oxygen – Compressed gas in a cylinder in laboratory settings (pure gases or mixtures with an oxidizing power greater than 23.5%).
Corrosion: (hand or material eroding upon contact) These products can damage your skin, causing redness, burns, blisters, and dermatitis. They can also damage your eyes. These products are also corrosive to metal.
  • Many cleaners are corrosive with a high pH 11-13 (Base) or a low pH 1-3 (Acid)
  • Chlorine bleach pH 11-13
  • Liquids that clean clogged drains, sinks, toilets pH 1-3
  • Lime and scale removers (Tub & Tile Cleaners) pH 11-13
Skull and Crossbones – Toxic:  These products poisonous. They can make you sick or kill you.
  • Commonly used toxic chemicals (if swallowed) include:
  • Antifreeze
  • Bleach
  • Drain Cleaners
  • Ammonia (can produce a toxic gas if mixed with other chemicals)
Health Hazard: These products can seriously damage your health. They can cause cancer, damage organs, negatively affect fertility and unborn children, kill you if swallowed.
  • When you are working with materials displaying the health hazard symbol, follow proper safety procedures and precautions to prevent short-term and long-term damage to your health.
  • Asbestos
  • Lead
  • Welding fumes – Hexavalent Chromium
Exclamation Point: These products can hurt you if they are breathed in or swallowed. They can irritate your eyes and skin, and make it hard to breathe. Some products can also make you dizzy or sleepy.
  • The solution is harmful, but it will not cause immediate damage upon contact with materials. Products with this symbol require proper ventilation, and usage to prevent injury
Gas Cylinder: This means the container hold gasses under pressure.
  • If the container is damaged, the gas can be released, causing a fire of explosion. The container can act like a missile when it explodes and can injure people in its path.
  • If the gas is poisonous it can make you or others nearby sick or it may cause death.
  • Check the cylinder labels carefully for other pictograms – Flammable – Oxidizer.
Exploding Bomb: These products are explosive – like dynamite. They can be a solid or liquid.

A sample of a Globally Harmonized System (GHS) label can be found below:

Elements of a Globally Harmonized System (GHS) label, product identifier, signal word, pictogram, hazard statements, precautionary statements.
Example: Gasoline Label – GHS Format (same product as before, you just have to pay twice as much now)

Example of chemical product labels used at Lawrence University.

Commonly used by custodians on campus.
Image of a Super Concentrated Glass & Hard Surface Cleaner labels – side label has corrosion symbol.
Bromicide Tablets label and symbols – OXIDIZER, CORROSION

Besides these Hazard Communication Symbols on labels, Safety Data Sheets can provide more detail on the hazards of a product. It will contain hazard statements and precautionary statements you can follow to work safely with the product.

Source: The Center for Construction Research and Training, “Hazard Alert – Hazard Communication A Guide to Symbols”.