GHS pictograms explained, with the meaning of all nine symbols
GHS pictograms identify chemical hazards using nine symbols. Check their meanings, why OSHA requires eight types, and how labels relate to SDSs.
GHS pictograms and what each symbol means
GHS pictograms are nine symbols used on chemical labels to identify physical, health or environmental hazards (HSE). US OSHA requires eight pictogram types as applicable to classification, excluding the environment symbol from its mandatory set (OSHA Appendix C).
Each pictogram is a black symbol on a white background, in a red frame shaped as a square set on a point (HSE, OSHA Appendix C). OSHA also prohibits blank red diamonds, and it selects pictograms by classification rather than a fixed count (OSHA Appendix C).
Chemical hazard pictograms and their meanings
| Symbol | What it means |
|---|---|
| Exploding bomb | Explosives, and certain self-reactive chemicals and organic peroxides |
| Flame | Flammable hazards and specified pyrophoric, self-heating, water-reactive, self-reactive and organic peroxide hazards |
| Flame over circle | Oxidisers |
| Gas cylinder | Gases under pressure (OSHA's current table also lists chemicals under pressure) |
| Corrosion | Corrosive to metals, severe skin burns or serious eye damage |
| Skull and crossbones | Severe acute toxicity |
| Exclamation mark | Harmful acute toxicity, irritation, skin sensitisation, respiratory tract irritation or narcotic effects |
| Health hazard | Carcinogenicity, germ cell mutagenicity, reproductive toxicity, respiratory sensitisation, target organ toxicity or aspiration toxicity |
| Environment (dead tree and fish) | Hazardous to the aquatic environment |
These are hazard summaries, not a classification checklist. The applicable category determines which symbol is required. Sources: OSHA Appendix C, HSE and ECHA.
Symbols people mix up
The corrosion symbol can mean metal corrosion, severe skin burns or serious eye damage. One symbol does not mean all three apply; read the hazard statements (OSHA Appendix C).
Skull and crossbones indicates severe acute toxicity, not all toxic effects. Under OSHA, categories 1 and 2 use "fatal" and category 3 uses "toxic", with statements specific to each exposure route. Less severe acute toxicity uses the exclamation mark instead (OSHA Appendix C).
The exclamation mark doesn't mean harmless. It covers harmful acute toxicity, skin and eye irritation and skin sensitisation. Under CLP in Great Britain, HSE also uses it for hazards to the ozone layer (HSE).
The health hazard symbol isn't limited to long-term effects: it also covers aspiration toxicity and single-exposure target organ effects. Skin sensitisation uses the exclamation mark, while respiratory sensitisation uses the health hazard symbol (OSHA Appendix C).
Flame over circle means oxidisers, not flammability (HSE). The dead tree and fish means aquatic hazards, not every environmental hazard (ECHA).
UK and US differences
Great Britain runs GB CLP, separately from EU CLP. Northern Ireland still follows EU CLP for substances and mixtures placed on its market (HSE). GB CLP, EU CLP and OSHA classifications and label rules differ (OSHA Appendix C). Don't assume one label design meets every market's rules.
Checking a label against the SDS
Under OSHA, section 2 of the safety data sheet (Hazard(s) Identification) contains the classification and label information. SDS symbols may be black-and-white graphics or symbol names (OSHA Appendix D).
Compare the label with section 2, checking the classification and hazard statements rather than the pictogram alone (OSHA Appendix C, OSHA Appendix D). A missing pictogram doesn't mean there is no classified hazard.
You can also ask RegAffairs AI, which answers what the GHS pictograms mean from CLP Annex V and an OSHA enforcement directive.