A pictogram on a container label is a diamond-shaped symbol with a red border, a white background, and a black image in the center that warns you about a specific type of chemical hazard. These standardized symbols are part of the Globally Harmonized System of Classification and Labelling of Chemicals (GHS), an international framework adopted by OSHA in the United States. There are nine pictograms in total, each representing a different category of danger, from flammability to cancer risk.
Why Pictograms Exist
Before the GHS system, chemical labels in different countries used different symbols, colors, and formats. A container that was clearly marked as dangerous in one country could be confusing or unreadable in another. The United Nations developed the GHS to create a single, universal visual language for chemical hazards. The idea is simple: no matter where a chemical was manufactured or where you encounter it, the same red-bordered diamond means the same thing.
OSHA aligned the U.S. Hazard Communication Standard with the GHS in 2012, and all hazardous chemicals shipped after June 1, 2015, have been required to carry these pictograms. A 2024 update further refined the standard to match the seventh revision of the GHS, improving label clarity and better aligning U.S. rules with Canada and other federal agencies.
What Each Pictogram Means
Each of the nine pictograms uses a distinct black symbol to represent a specific type of hazard. Here’s what you’ll see and what it tells you:
- Flame: The product is flammable. This covers flammable liquids, gases, aerosols, and solids, as well as chemicals that can self-ignite.
- Flame over circle: The product is an oxidizer, meaning it can intensify a fire or cause one by feeding oxygen to other materials.
- Exploding bomb: The product is explosive or can react violently under certain conditions, such as heat or shock.
- Skull and crossbones: The product can cause death or serious harm from a single or short-term exposure through swallowing, skin contact, or breathing it in. This is the acute toxicity warning for the most dangerous categories.
- Corrosion (liquid eating through material and skin): The product can cause severe skin burns, serious eye damage, or corrode metals on contact.
- Gas cylinder: The container holds gas under pressure, which can explode if heated or rupture violently.
- Exclamation mark: The product poses lower-level hazards such as skin irritation, eye irritation, or harmful (not fatal) effects from a single exposure. Think of it as the less severe counterpart to the skull and crossbones.
- Health hazard (silhouette with a starburst on the chest): The product can cause serious long-term health problems. This includes cancer risk, genetic damage, reproductive harm, respiratory sensitization, and organ damage from repeated exposure. These effects may not show up immediately.
- Environment (dead fish and tree): The product is toxic to aquatic life. OSHA includes this pictogram in its standard, though its enforcement focus is primarily on workplace health rather than environmental protection.
Other Elements on the Label
Pictograms don’t appear alone. OSHA requires six elements on every hazardous chemical label: the pictogram(s), a product identifier (the chemical name), a signal word, hazard statements, precautionary statements, and the name, address, and phone number of the manufacturer or importer.
The signal word is either “Danger” or “Warning.” “Danger” appears on the most severe hazard categories. For example, a chemical that is immediately fatal if swallowed gets “Danger,” while one that is merely harmful at higher doses gets “Warning.” You will never see both words on the same label for the same hazard. If a chemical has multiple hazards with different severity levels, the more serious signal word takes priority.
Hazard statements describe the specific nature of the risk in plain language, like “fatal if inhaled” or “causes serious eye damage.” Precautionary statements tell you what to do (or avoid) to stay safe, and what to do if something goes wrong.
How Pictograms Differ From the NFPA Diamond
If you’ve seen a multicolored diamond on a building wall or storage tank with numbers in blue, red, yellow, and white sections, that’s the NFPA 704 system, sometimes called the “fire diamond.” It serves a different purpose and audience than GHS pictograms.
The NFPA diamond is designed for emergency responders arriving at a fire or chemical spill. It uses a 0-to-4 number scale for health, flammability, and instability, giving firefighters a quick severity rating from the outside of a building. It only covers short-term, acute hazards, the kind that matter during an emergency.
GHS pictograms, on the other hand, are designed for workers handling chemicals day to day. They cover both acute hazards (like burns on contact) and chronic hazards (like cancer from repeated exposure over months or years). A container label with GHS pictograms also includes much more detail: specific hazard statements, precautionary steps, and manufacturer contact information. The two systems can coexist in the same facility, but they serve different needs.
Where You’ll See Pictograms
Any container of a hazardous chemical in a workplace should carry GHS pictograms on its label. This includes bottles of industrial solvents, cleaning products, paints, adhesives, laboratory reagents, and pesticides. Consumer products you buy at a hardware store or home improvement center may also carry these symbols, though consumer labeling rules can vary slightly from workplace requirements.
The same pictogram information also appears in Section 2 of the Safety Data Sheet (SDS), the detailed document that accompanies every hazardous chemical in a workplace. If a label is damaged or hard to read, the SDS for that product contains the full hazard classification, all applicable pictograms, and every required statement. Employers are required to keep SDSs accessible to workers for every hazardous chemical on site.
A single container can carry more than one pictogram. A product that is both flammable and acutely toxic, for example, would display both the flame and the skull and crossbones. The number of pictograms on a label gives you a quick visual sense of how many different types of risk that chemical poses.