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Short answer
The corrosive symbol is the GHS “Corrosion” pictogram: a black symbol on a white background inside a red-bordered square set on a point. On a US label under OSHA’s Hazard Communication Standard it marks three hazards: skin corrosion (Category 1), serious eye damage (Category 1) and corrosive to metals (Category 1). The signal word, “Danger” or “Warning”, tells you which.
The detail that matters most: one symbol covers two very different hazards. A product that only attacks metal carries it with “Warning”; a product that destroys skin or eye tissue carries it with “Danger”.
Definition and scope
OSHA’s Appendix C to 29 CFR 1910.1200 requires each pictogram to be a square set at a point with a black hazard symbol on a white background and a red frame wide enough to be clearly visible. It allows eight standard symbols, and “Corrosion” is the one listed for corrosives. OSHA’s pictogram quick card (OSHA 3491-08R, 2024) lists the three hazards that use it: skin corrosion/burns, eye damage and corrosive to metals.
Each hazard has a defined meaning. Skin corrosion is irreversible damage to the skin, visible necrosis through the epidermis and into the dermis (Appendix A, A.2.1.1). Serious eye damage is tissue damage in the eye, or serious physical decay of vision, that is not fully reversible (A.3.1.1). Corrosive to metals means a corrosion rate on steel or aluminum above 6.25 mm per year at 55 °C (131 °F) (Appendix B, B.16). For how each test works, see corrosive fluids: skin, metal and transport definitions.
Canada’s WHMIS uses the same pictogram for the same three classes, according to the Canadian Centre for Occupational Health and Safety (CCOHS).
How the symbol is used on a label
Four label rules from OSHA decide what you actually see:
- One symbol, one appearance. Each pictogram may appear only once on a label, even when several hazards call for it (OSHA quick card). A product that is both corrosive to metals and corrosive to skin shows a single Corrosion pictogram.
- “Danger” outranks “Warning”. If “Danger” is included, “Warning” shall not appear (Appendix C, C.2.1.1). That same product therefore carries “Danger”.
- The exclamation mark steps aside. If the corrosive pictogram is included, the exclamation mark shall not appear where it is used for skin or eye irritation (C.2.1.3). The rule is limited to the exclamation mark’s use for irritation, so a corrosive label does not repeat the milder irritation symbol.
- Respiratory tract. If the classifier determines from skin or eye data that a chemical may be corrosive to the respiratory tract, that hazard must also be communicated with the corrosive pictogram and the statement “corrosive to the respiratory tract” (notes under C.4.4 and C.4.5).
Which hazard classes carry it
Hazard statements are printed in full on the label. The H-codes below come from the UN GHS (Rev. 11, 2025, as summarised by NIH’s PubChem); OSHA’s Appendix C gives the same wording without the codes. For the full classification logic see GHS classification of chemicals.
| Hazard class and category | Pictogram | Signal word | Label statement | H-code | UN Model Regulations class listed |
|---|---|---|---|---|---|
| Skin corrosion, Category 1 (1A, 1B, 1C) | Corrosion | Danger | Causes severe skin burns and eye damage | H314 | Class 8 |
| Serious eye damage, Category 1 | Corrosion | Danger | Causes serious eye damage | H318 | None listed |
| Corrosive to metals, Category 1 | Corrosion | Warning | May be corrosive to metals | H290 | Class 8 |
| Skin irritation, Category 2 | Exclamation mark | Warning | Causes skin irritation | H315 | None listed |
| Eye irritation, Category 2A | Exclamation mark | Warning | Causes serious eye irritation | H319 | None listed |
OSHA splits skin corrosion into sub-categories 1A, 1B and 1C by how long the exposure and observation periods are, but all three are regulated as Category 1 (Appendix A, A.2.2.2.1.2). The pictogram and signal word do not change between them.
Neighbouring pictograms people search for
These are the other symbols searchers often look up next to the corrosive symbol, with the hazards OSHA assigns to them (Appendix C, Figure C.1, and the OSHA quick card):
| Pictogram | Hazards it covers |
|---|---|
| Flame | Flammables, pyrophorics, self-heating, emits flammable gas, self-reactives, organic peroxides, desensitized explosives |
| Exploding bomb | Explosives, self-reactives, organic peroxides |
| Gas cylinder | Gases under pressure, chemicals under pressure |
| Health hazard | Carcinogen, respiratory sensitizer, reproductive toxicity, target organ toxicity, mutagenicity, aspiration toxicity |
The full set, including signal words and precautionary statements, is in understanding GHS labels.
Where it matters for labs, clinics and supply decisions
Read the statement, not only the symbol. The same pictogram sits above “Danger / Causes severe skin burns and eye damage” and above “Warning / May be corrosive to metals”. Only the signal word and hazard statement separate a tissue hazard from a materials hazard.
The precautionary statements differ by class. For corrosive to metals, OSHA’s Appendix C (C.4.29) assigns “Keep only in original packaging”, “Absorb spillage to prevent material damage” and “Store in corrosive resistant/… container with a resistant inner liner”; the last may be omitted when the original-packaging statement is on the label. For skin corrosion (C.4.4), it assigns “Wear protective gloves/protective clothing/eye protection/face protection” and “Store locked up”.
Materials are named in the test. The metals-corrosion test uses steel and aluminum specimens, so those are the metals the classification speaks to. Where a label’s statement specifies a compatible container material, that specification comes from the chemical manufacturer, importer or distributor (Appendix C).
Transport is a separate system. PubChem’s GHS summary lists UN Model Regulations Class 8 against H290 and H314 but no class against H318, so the workplace pictogram and the transport class do not map one-to-one. For the transport side, see corrosive fluids; for handling, storage and first-aid context, see corrosive chemicals in the lab.
For the rules that decide which labels and data sheets a research laboratory must have, see the Hazard Communication Standard in the research laboratory.
Common misunderstandings
- “Corrosive means acid.” The classes are defined by effect: tissue destruction, eye damage or metal corrosion rate. The symbol follows the classification, not the chemical family.
- “A corrosion symbol always means skin burns.” Not when the signal word is “Warning” and the statement reads “May be corrosive to metals”.
- “An exclamation mark is a weaker corrosive.” It marks skin irritation Category 2 or eye irritation Category 2A, which are separate categories. Appendix A defines skin irritation as reversible damage to the skin and skin corrosion as irreversible damage.
- “1A, 1B and 1C get different symbols.” They do not; all are Category 1.
- “Two corrosion symbols mean two hazards.” A pictogram appears only once on a label.
FAQ
What does the corrosive symbol mean?
It is the GHS Corrosion pictogram. Under OSHA’s Hazard Communication Standard it flags skin corrosion Category 1, serious eye damage Category 1 or corrosive to metals Category 1; read the signal word and hazard statement to see which applies.
What are the flammable, explosive, gas under pressure and health hazard symbols?
They are the Flame, Exploding bomb, Gas cylinder and Health hazard pictograms. The table above lists the hazards OSHA assigns to each.
What does the corrosive symbol look like?
It is a black hazard symbol on a white background inside a red frame, in the shape of a square set at a point. OSHA requires the red frame to be sufficiently wide to be clearly visible, and a red frame without a hazard symbol is not a pictogram (Appendix C, C.2.3.1).
Sources
- OSHA, 29 CFR 1910.1200 Appendix C, Allocation of Label Elements (text as of 2026-11-07): osha.gov/laws-regs/regulations/standardnumber/1910/1910.1200AppC
- OSHA, 29 CFR 1910.1200 Appendix A, Health Hazard Criteria (as of 2026-11-07): osha.gov/laws-regs/regulations/standardnumber/1910/1910.1200AppA
- OSHA, 29 CFR 1910.1200 Appendix B, Physical Hazard Criteria, B.16 Corrosive to Metals (as of 2026-11-07): osha.gov/laws-regs/regulations/standardnumber/1910/1910.1200AppB
- OSHA, HCS Pictograms and Hazards quick card, OSHA 3491-08R 2024 (as of 2026-11-07): osha.gov/sites/default/files/publications/OSHA3491QuickCardPictogram.pdf
- NIH PubChem, GHS Classification Summary, UNECE GHS Rev. 11 (2025) (as of 2026-11-07): pubchem.ncbi.nlm.nih.gov/ghs
- CCOHS, OSH Answers: WHMIS pictograms, fact sheet last revised 2026-05-28 (as of 2026-11-07): ccohs.ca/oshanswers/chemicals/whmis_ghs/pictograms.html
