The Globally Harmonized System of Classification and Labelling of Chemicals (GHS) uses a standardized set of pictograms to communicate hazards at a glance. In the United States, OSHA's Hazard Communication Standard (HCS 2012) requires these pictograms on workplace chemical labels and Safety Data Sheets.
There are nine pictograms in total. Each one represents a specific category of hazard. Getting them right on your labels isn't optional—it's a regulatory requirement. And getting them wrong is one of the fastest ways to trigger an OSHA citation or a rejected product listing.
All nine GHS hazard pictograms used in chemical product labeling under OSHA's Hazard Communication Standard.
The 9 GHS Pictograms Explained
1. Health Hazard (Silhouette)
Indicates serious long-term health effects: carcinogenicity, respiratory sensitization, reproductive toxicity, target organ toxicity, mutagenicity, and aspiration hazard. This is the pictogram most often confused with the exclamation mark—but they cover very different severity levels.
2. Flame
Used for flammable gases, aerosols, liquids, and solids. Also covers pyrophoric materials, self-heating substances, and chemicals that emit flammable gases on contact with water. If your product has a flash point below 93°C (200°F), this pictogram is almost certainly required.
3. Exclamation Mark
Covers acute toxicity (less severe), skin and eye irritation, skin sensitization, narcotic effects, and respiratory tract irritation. Think of this as the "caution-level" health hazard—serious enough to warn about, but not the long-term systemic effects covered by the health hazard silhouette.
4. Gas Cylinder
Indicates gases under pressure: compressed gases, liquefied gases, refrigerated liquefied gases, and dissolved gases. These products pose a physical hazard because the container can explode if heated or damaged.
5. Corrosion
Used for chemicals that cause skin corrosion, serious eye damage, or are corrosive to metals. If your product can cause visible destruction or irreversible damage to skin tissue on contact, this pictogram is required.
6. Exploding Bomb
Covers explosives, self-reactive substances, and organic peroxides that may explode under certain conditions. This includes products that can mass-explode, project fragments, or create a fire/blast hazard.
7. Flame Over Circle (Oxidizer)
Indicates oxidizing gases, liquids, and solids. These chemicals can cause or intensify fire by providing oxygen. They may not be flammable themselves, but they make other materials burn more intensely—a critical distinction for storage and handling.
8. Skull and Crossbones
Reserved for acute toxicity at the most severe levels (Categories 1, 2, and 3). If a product can cause death or serious harm through a single or short-term exposure via oral, dermal, or inhalation routes, this pictogram applies.
9. Environment
Indicates hazards to the aquatic environment (acute and chronic). While OSHA does not require this pictogram on workplace labels in the U.S., it is required under GHS for international markets and is commonly included on SDS documents for completeness.
Common Pictogram Mistakes We See
- Using the exclamation mark when the health hazard silhouette is required (or vice versa)
- Including the environment pictogram on U.S. workplace labels where OSHA doesn't require it, while omitting ones that are required
- Printing pictograms too small to be clearly visible at normal viewing distance
- Using outdated or non-standard pictogram artwork instead of the official red-bordered diamonds
- Listing pictograms on the label that don't match the hazard classification on the SDS
Pictogram Precedence Rules
GHS includes precedence rules that determine which pictograms appear when multiple hazards apply. Understanding these prevents cluttered, confusing labels:
- Skull and crossbones takes precedence over the exclamation mark for acute toxicity
- Corrosion takes precedence over the exclamation mark for skin/eye effects
- Health hazard (silhouette) takes precedence over the exclamation mark for respiratory sensitization
- If a product triggers both the skull and crossbones AND the health hazard silhouette, both appear
Quick Reference
OSHA's Hazard Communication Standard requires that GHS pictograms appear as a red-bordered diamond (rotated square) on a white background. Black-and-white pictograms, colored backgrounds, or non-standard shapes do not meet the requirement. The pictogram must be clearly visible and proportionate to the label size.
Reference: OSHA Hazard Communication Pictograms
Not sure you have the right pictograms?
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