GHS Hazard Symbols and Meanings: The Complete Reference
GHS hazard symbols appear on every chemical label and Safety Data Sheet in the world. But what exactly does each symbol mean — and what hazard statements go with it? This reference guide covers all 9 GHS pictograms with their associated hazard classes, H-statements, and signal words.
How GHS Symbols Work
Each GHS pictogram represents one or more hazard classes. A single chemical can carry multiple pictograms if it has multiple hazards. For example, acetone is both flammable (GHS02) and causes eye irritation (GHS07).
The symbol alone tells you the type of hazard. The hazard statement (H-phrase) tells you the specific nature and severity. Together with the signal word (DANGER or WARNING), they give you everything you need to understand the risk at a glance.
Complete GHS Symbol Reference Table
| Pictogram | Code | Hazard Category | Signal Word | Key H-Statements |
|---|---|---|---|---|
| Exploding Bomb | GHS01 | Explosives, Self-reactive (A/B), Organic peroxides (A/B) | DANGER | H200, H201, H202, H240, H241 |
| Flame | GHS02 | Flammable gas/liquid/solid, Pyrophoric, Self-heating, Water-reactive | DANGER / WARNING | H220, H224, H225, H226, H228, H250, H251 |
| Flame Over Circle | GHS03 | Oxidising gas/liquid/solid | DANGER / WARNING | H270, H271, H272 |
| Gas Cylinder | GHS04 | Gases under pressure | WARNING | H280, H281 |
| Corrosion | GHS05 | Skin corrosion Cat 1, Eye damage Cat 1, Corrosive to metals | DANGER | H290, H314, H318 |
| Skull & Crossbones | GHS06 | Acute toxicity Cat 1–3 (oral/dermal/inhalation) | DANGER | H300, H301, H310, H311, H330, H331 |
| Exclamation Mark | GHS07 | Acute toxicity Cat 4, Irritant, Sensitiser, STOT SE Cat 3 | WARNING | H302, H312, H315, H317, H319, H332, H335, H336 |
| Health Hazard | GHS08 | Carcinogen, Mutagen, Reprotoxin, STOT SE/RE, Aspiration | DANGER / WARNING | H334, H340–H373 |
| Environmental | GHS09 | Aquatic acute Cat 1, Aquatic chronic Cat 1–2 | WARNING | H400, H410, H411 |
GHS01 — Exploding Bomb: Hazards and Statements
The exploding bomb covers the most energetically unstable substances. These chemicals can detonate or deflagrate under certain conditions.
Associated H-statements:
- H200 — Unstable explosive
- H201 — Explosive; mass explosion hazard
- H202 — Explosive; severe projection hazard
- H203 — Explosive; fire, blast or projection hazard
- H204 — Fire or projection hazard
- H240 — Heating may cause an explosion (self-reactive substances)
- H241 — Heating may cause a fire or explosion
Signal word is always DANGER for this pictogram.
Storage requirements: dedicated explosive magazines, anti-static measures, restricted access. Many jurisdictions require special permits for storage above threshold quantities.
GHS02 — Flame: Hazards and Statements
Flammable substances are classified by their flash point (liquids), lower flammable limit (gases), or ignitability (solids).
Associated H-statements:
- H220 — Extremely flammable gas
- H221 — Flammable gas
- H222 — Extremely flammable aerosol
- H223 — Flammable aerosol
- H224 — Extremely flammable liquid and vapour (flash point < 23°C, bp ≤ 35°C)
- H225 — Highly flammable liquid and vapour (flash point < 23°C)
- H226 — Flammable liquid and vapour (flash point 23–60°C)
- H228 — Flammable solid
- H250 — Catches fire spontaneously if exposed to air (pyrophoric)
- H251 / H252 — Self-heating; may catch fire (self-heating substances)
- H260 / H261 — In contact with water releases flammable gas
Practical note: Flash point is the single most important parameter for flammable liquid classification. Any liquid with flash point < 60°C requires GHS flammable labelling.
GHS03 — Flame Over Circle: Oxidisers
Oxidisers are frequently misunderstood. They are not themselves flammable, but they dramatically accelerate combustion by providing additional oxygen to a fire.
Associated H-statements:
- H270 — May cause or intensify fire; oxidiser (gas)
- H271 — May cause fire or explosion; strong oxidiser (liquid/solid)
- H272 — May intensify fire; oxidiser (liquid/solid)
Never store oxidisers with flammables, organic materials, or reducing agents. This is one of the fundamental rules of chemical storage compatibility.
GHS04 — Gas Cylinder: Pressure Hazards
Associated H-statements:
- H280 — Contains gas under pressure; may explode if heated
- H281 — Contains refrigerated gas; may cause cryogenic burns or injury
Compressed gas cylinders must be stored upright, chained or strapped to prevent falling, away from heat sources, and in well-ventilated areas. Cryogenic liquids (liquid nitrogen, liquid helium) add the risk of asphyxiation in enclosed spaces.
GHS05 — Corrosion: Chemical Burns
Associated H-statements:
- H290 — May be corrosive to metals
- H314 — Causes severe skin burns and eye damage (Skin Corr. Cat 1)
- H318 — Causes serious eye damage (Eye Dam. Cat 1)
Skin corrosion (H314) means visible destruction of skin tissue within 4 hours. Eye damage (H318) means irreversible damage within 21 days. Always use chemical-resistant gloves, face shield, and lab coat when handling corrosives.
GHS06 — Skull and Crossbones: Acute Toxicity
Associated H-statements by route of exposure:
Oral (ingestion):
- H300 — Fatal if swallowed (Cat 1–2, ATE ≤ 50 mg/kg)
- H301 — Toxic if swallowed (Cat 3, ATE ≤ 300 mg/kg)
- H302 — Harmful if swallowed (Cat 4 — but this uses GHS07, not GHS06)
Dermal (skin contact):
- H310 — Fatal in contact with skin (Cat 1–2, ATE ≤ 200 mg/kg)
- H311 — Toxic in contact with skin (Cat 3, ATE ≤ 1,000 mg/kg)
Inhalation:
- H330 — Fatal if inhaled (Cat 1–2)
- H331 — Toxic if inhaled (Cat 3)
GHS06 is assigned to Categories 1, 2, and 3. Category 4 gets the less severe GHS07 (exclamation mark) instead.
GHS07 — Exclamation Mark: Mild to Moderate Hazards
This is the most common GHS pictogram because it covers a wide range of moderate hazards.
Associated H-statements:
- H302 — Harmful if swallowed (acute oral Cat 4)
- H312 — Harmful in contact with skin (acute dermal Cat 4)
- H315 — Causes skin irritation (Skin Irrit. Cat 2)
- H317 — May cause an allergic skin reaction (Skin Sens. Cat 1)
- H319 — Causes serious eye irritation (Eye Irrit. Cat 2)
- H332 — Harmful if inhaled (acute inhalation Cat 4)
- H335 — May cause respiratory irritation (STOT SE Cat 3)
- H336 — May cause drowsiness or dizziness (STOT SE Cat 3 — narcotic effects)
Note: GHS07 and GHS06 are never used together for the same route of exposure. If GHS06 applies (more severe), GHS07 is dropped for that route.
GHS08 — Health Hazard: Long-term Effects
Associated H-statements:
Carcinogenicity:
- H350 — May cause cancer (Cat 1A/1B)
- H351 — Suspected of causing cancer (Cat 2)
Mutagenicity:
- H340 — May cause genetic defects (Cat 1A/1B)
- H341 — Suspected of causing genetic defects (Cat 2)
Reproductive toxicity:
- H360 — May damage fertility or the unborn child (Cat 1A/1B)
- H361 — Suspected of damaging fertility or the unborn child (Cat 2)
- H362 — May cause harm to breast-fed children
Specific target organ toxicity:
- H370 — Causes damage to organs (STOT SE Cat 1)
- H371 — May cause damage to organs (STOT SE Cat 2)
- H372 — Causes damage to organs through prolonged or repeated exposure (STOT RE Cat 1)
- H373 — May cause damage to organs through prolonged or repeated exposure (STOT RE Cat 2)
Aspiration hazard:
- H304 — May be fatal if swallowed and enters airways (Asp. Tox. Cat 1)
Respiratory sensitisation:
- H334 — May cause allergy or asthma symptoms or breathing difficulties if inhaled
GHS09 — Environmental: Aquatic Toxicity
Associated H-statements:
- H400 — Very toxic to aquatic life (Aquatic Acute Cat 1, LC50 ≤ 1 mg/L)
- H410 — Very toxic to aquatic life with long lasting effects (Aquatic Chronic Cat 1)
- H411 — Toxic to aquatic life with long lasting effects (Aquatic Chronic Cat 2)
- H412 — Harmful to aquatic life with long lasting effects (Aquatic Chronic Cat 3) — no pictogram
- H413 — May cause long lasting harmful effects to aquatic life (Aquatic Chronic Cat 4) — no pictogram
Note that H412 and H413 do not trigger GHS09 — only the more severe Acute Cat 1 and Chronic Cat 1–2 classifications require the pictogram.
Calculating Mixture Classifications
When a substance is a component in a chemical mixture, its individual ATE value contributes to the mixture’s overall toxicity classification. The GHS additivity formula is:
100 / ATE_mix = Σ (Ci / ATE_i)Use our ATE Mixture Calculator to calculate the acute toxicity classification for your formulation automatically — with PDF export for SDS documentation.
Related Resources
- GHS H-Statements Complete Guide — H-codes associated with each pictogram
- GHS Signal Words: Danger vs Warning — which pictograms trigger Danger vs Warning
- GHS Health Hazard Symbol Explained — deep dive into GHS08
- GHS P-Statements Guide — precautionary codes for each hazard class
Reference: UN GHS Rev.9 — Chapters 2.1–3.11. CLP Regulation (EC) No 1272/2008 — Annex I.