In 2012, OSHA revised its Hazard Communication Standard (HCS) to be compatible with the United Nations' Globally Harmonized System of Classification and Labeling of Chemicals (GHS).
These systems exist to ensure that people recognize any hazardous chemicals in their workplace, understand the dangers they face, and know the precautions they need to take.
As an international standard, GHS uses hazard symbols to convey information without relying on a specific language. Let's look at these hazard pictograms' meanings.
What Type of Hazards Do the Standard Pictograms Represent?
There are thousands of hazardous chemicals used and transported for commercial purposes. The GHS standard streamlines all this information by grouping chemicals into classes. There are 29 GHS hazard classes that describe the hazard type and sometimes a chemical's current state (liquid, solid, or gas).
Hazard classes are broken down into three main types: physical hazards (17 classes), health hazards (10 classes), and environmental hazards (2 classes).
Since there are only 9 GHS pictograms for 29 classes, not every hazard class has its own symbol. Instead, the GHS pictograms represent multiple hazard classes with a similar type and level of risk.
GHS Hazardous Symbols and Meanings
GHS pictograms are designed to draw your attention to a certain type of risk. They provide important, instantly recognizable information, but you may notice that some very different hazards get grouped together below.
That's because hazard symbols never stand alone. They're just one part of a standardized GHS label that provides more details about how to safely handle each substance.
Multiple hazard pictograms can appear on a label when they apply. GHS pictograms may also be used on hazard signs to encourage caution in a specific storage or work area.
Health Hazard Symbols and Meanings
There are four GHS symbols used to warn about health hazards like poisoning, tissue irritation, or causing disease.
All of the health hazard symbols mean you need to keep containers tightly closed until you've read more information and taken the recommended precautions.
Toxic GHS Symbol
he skull-and-crossbones GHS pictogram, widely known as the toxic symbol, represents chemicals with the highest levels of acute toxicity. That means these chemicals have an immediate and severe (even lethal) effect on human health.
Depending on the chemical, exposure may occur by inhaling, ingesting, or making skin contact with the substance. You'll find the particular exposure route(s) elsewhere on the label.
Harmful GHS Symbol
The GHS pictogram with an exclamation mark is used on substances that are harmful or irritating. The health effects are acute (set in quickly), but they're less severe than something marked with the toxic symbol.
Chemical classes include:
- Skin, eye, or respiratory tract irritants
- Skin sensitizers, which cause an allergic response
- The lowest level of acutely toxic chemicals
- Materials with narcotic effects (drowsiness, lack of coordination, and dizziness)
Specific warnings and precautions will appear on the label.
Health Hazard GHS Symbol
The health hazard pictogram is used for substances that present a health hazard over time.
Chemical classes include:
- Carcinogens, which cause cancer
- Respiratory sensitizers
- Agents with reproductive toxicity that affects fertility or in utero(子宫) development
- Chemicals with target organ toxicity
- Mutagenic ( 致变异）chemicals that cause genetic defects
- Substances with aspiration toxicity
You can learn about the specific health risk(s) in the label's text.
Physical Hazard Pictogram Meanings
There are five GHS symbols used to warn about physical hazards, which are characteristics that can put both property and human safety at risk.
Corrosive GHS Symbol
The corrosive GHS pictogram represents substances that eat away at a material when they make contact.
This symbol covers both physical and health hazard classes – that's why it depicts both a hand and a surface.
Chemical classes include:
- Skin corrosion or burns
- Eye damage
- Corrosive to metals
The GHS label will specify which materials or exposure routes can be corroded by a substance. Like all health hazard symbols, you should leave the container tightly sealed until you know more. Also, you'll need to consider the types of tools or containers you can safely use.
Explosive GHS Symbol
The explosive GHS pictogram marks a chemical as unstable and capable of causing a fire or explosion.
Chemical classes include:
- Explosives
- Self-reactive chemicals
- Organic peroxides
The explosive pictogram means you need more information before you come anywhere near that container. Different chemicals can be set off under different conditions, including friction or mechanical shock – even bumping these containers with another object may be dangerous.
Flammable GHS Symbol
The flammable GHS pictogram is used on chemicals that emit flammable gas or could self-ignite when exposed to water or air.
Chemical classes include:
- Flammable gases, liquids, and solids
- Pyrophoric materials
- Self-reactive materials that aren't also explosive
- Organic peroxides that aren't also explosive
- Water-reactives
This pictogram means you should leave the container tightly closed and away from any sources of heat until you know more. You also need to be careful about changing any storage conditions, including what other substances or materials get placed near these containers.
Oxidizing GHS Symbol
The oxidizing GHS pictogram is used for oxidizing solids, liquids, and gases. These chemical classes, when exposed to oxygen, help ignite substances that wouldn't otherwise combust and/or make fires burn hotter and longer.
Like the flammable symbol, this pictogram also means you should leave the container tightly sealed until you know more. Don't change storage conditions or put other materials near these containers until you know what's safe.
Compressed Gas GHS Symbol
The compressed gas GHS pictogram is used on gases that are stored under pressure.
Chemical classes include:
- Compressed gases
- Liquefied gases
- Refrigerated liquefied gases
- Dissolved gases
Containers with this hazard symbol may explode if heated. It's best not to even touch these containers until you know more because some require special handling precautions.
Environmental Hazard GHS Symbol
Only one of the GHS & OSHA pictograms addresses an environmental hazard.
The environmental hazard GHS pictogram indicates that a chemical is toxic to aquatic wildlife. This is the only GHS symbol that's not mandatory.
When you see this symbol, disposal of the substance may require a specific method. You also need to take precautions against release into the environment during use or transportation.
