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Short answer: the exclamation mark pictogram on a chemical label signals a lower-tier health hazard under OSHA’s Hazard Communication Standard: acute toxicity (category 4), skin or eye irritation, skin sensitization, or respiratory irritation and drowsiness. Every OSHA row that uses it carries the signal word “Warning”. It does not mean the chemical is safe, and it is sometimes left off a label when a more serious pictogram already covers the same hazard.
This page is for lab staff and safety officers who need to read a label correctly. It covers the classes that use the symbol, the rules that remove it, and a short checklist for reading it at the bench. It is general information, not a substitute for the product’s safety data sheet or your institution’s chemical hygiene plan.
What the exclamation mark pictogram indicates
OSHA’s Hazard Communication Standard (29 CFR 1910.1200) defines a pictogram as “a composition that may include a symbol plus other graphic elements, such as a border, background pattern, or color” that conveys specific information about a chemical’s hazards. The exclamation mark is one of the symbols used for health hazards. Appendix C of the standard (Allocation of Label Elements) assigns it to the hazard classes below. Supplier catalogues and safety data sheets often refer to the pictogram by its UN GHS code, GHS07; OSHA’s own text uses the name “exclamation mark”.
Which hazard classes use it
| Hazard class | Category | Signal word | Hazard statement on the label |
|---|---|---|---|
| Acute toxicity, oral | 4 | Warning | Harmful if swallowed |
| Acute toxicity, dermal | 4 | Warning | Harmful in contact with skin |
| Acute toxicity, inhalation | 4 | Warning | Harmful if inhaled |
| Skin corrosion/irritation | 2 | Warning | Causes skin irritation |
| Eye damage/irritation | 2A | Warning | Causes serious eye irritation |
| Skin sensitization | 1 (1A and 1B) | Warning | May cause an allergic skin reaction |
| Specific target organ toxicity, single exposure | 3 | Warning | May cause respiratory irritation, or May cause drowsiness or dizziness |
Source: 29 CFR 1910.1200 Appendix C, osha.gov, read 2026-11-08. Eye irritation category 2B has no pictogram in the OSHA table, so a 2B-only chemical carries no exclamation mark.
Acute toxicity
Only the lowest-severity acute toxicity category in the table (category 4) uses the exclamation mark, with the statements “Harmful if swallowed”, “Harmful in contact with skin” and “Harmful if inhaled”, one per exposure route.
Irritation and sensitization
Skin irritation (category 2) and serious eye irritation (category 2A) share the symbol with skin sensitization (category 1). Irritation is a local effect; the sensitization statement, “May cause an allergic skin reaction”, refers to an allergic response. For the stronger skin and eye classes that use a different symbol, see the corrosive symbol guide.
Respiratory irritation and drowsiness
Single-exposure specific target organ toxicity category 3 covers two statements under the same symbol: respiratory irritation, and drowsiness or dizziness.
When the exclamation mark is not used
Appendix C also removes the symbol in specific cases. These rules matter because a label with no exclamation mark can still describe an irritant or an acute toxicant.
| Situation | What Appendix C says | Paragraph |
|---|---|---|
| Skull and crossbones pictogram is on the label | The exclamation mark does not appear where it would be used for acute toxicity. | C.2.1.2 |
| Corrosive pictogram is on the label | The exclamation mark does not appear where it would be used for skin or eye irritation. | C.2.1.3 |
| Health hazard pictogram is on the label for respiratory sensitization | The exclamation mark does not appear where it would be used for skin sensitization or skin or eye irritation. | C.2.1.4 |
| Signal word “Danger” is on the label | “Warning” does not appear, even if the exclamation mark classes alone would have called for it. | C.2.1.1 |
| Same pictogram needed for several hazards | A pictogram may appear only once on a label. | C.2.3.4 |
| Hazard Not Otherwise Classified (HNOC) | The exclamation mark is permitted but not required, provided the words “Hazard Not Otherwise Classified” or “HNOC” appear below it. | C.2.3.3 |
Source: 29 CFR 1910.1200 Appendix C, osha.gov, read 2026-11-08.
Reading it on a lab label
- Read the signal word first. “Warning” with an exclamation mark fits the table above; “Danger” means a more severe classification is also present.
- Read the hazard statements, not just the symbol. One symbol covers several different hazards, and the text tells you which applies.
- Look for other pictograms. A skull and crossbones, corrosive or health hazard symbol can displace the exclamation mark for the same hazard, so its absence proves nothing about irritation or toxicity.
- Open the safety data sheet for the full classification, since the label shows only the elements the standard requires. The wider context is in the guide to GHS labels, pictograms, signal words and hazard statements and the guide to GHS classification of chemicals.
Common misunderstandings
- “It means a general warning.” In the OSHA table it maps to specific classes; it is not a catch-all caution sign.
- “No exclamation mark means no irritation.” Precedence rules C.2.1.2 to C.2.1.4 can remove it when a more serious pictogram is present.
- “Warning means harmless.” The statements still describe real acute toxicity, irritation or sensitization effects.
- “The symbol appears once per hazard.” Under C.2.3.4 it appears once per label, however many of its classes apply.
FAQ
What does the exclamation mark pictogram indicate?
A health hazard in one of the classes in the table above, such as category 4 acute toxicity, skin or eye irritation, skin sensitization or respiratory irritation, under the signal word “Warning”.
What does the exclamation mark pictogram from OSHA indicate?
OSHA’s Appendix C to 29 CFR 1910.1200 assigns it to the seven rows listed under “Which hazard classes use it”. OSHA also sets the rules under which it is omitted from a label.
What does the exclamation mark on a hazard pictogram mean?
It marks the lower-severity health hazards above. It is not a sign that the chemical is safe, and it can be absent when a skull and crossbones, corrosive or health hazard pictogram already covers the hazard.
Is GHS07 the same thing?
GHS07 is the code commonly used on safety data sheets and supplier labels for this pictogram. OSHA’s regulation refers to it by name.
Who is Mark in the Bible?
That question is unrelated to chemical labelling and is not covered here; this page is about the hazard pictogram only.
