When is the exclamation mark used instead of the skull?

For the least severe acute toxicity, Category 4 (“Harmful”). Categories 1–3 (“Fatal”/“Toxic”) use the skull-and-crossbones (GHS06); Category 4 uses the exclamation mark (GHS07).

Does the skull cover all three exposure routes?

Yes — it applies to oral (H300/H301), dermal (H310/H311), and inhalation (H330/H331) acute toxicity in Categories 1–3.

GHS / HazCom term · Glossary

GHS06 (Skull and Crossbones)

Verified vs OSHA sources · 2026-10-05

The GHS hazard pictogram showing a skull and crossbones. It marks the more severe acute toxicity — Categories 1, 2, and 3 by oral, dermal, or inhalation route — chemicals that can be fatal or toxic from a small, single exposure. The milder Category 4 (“harmful”) uses the exclamation mark (GHS07) instead.

29 CFR 1910.1200 App C

Also known as: skull and crossbones, toxic pictogram, poison symbol

GHS06 (Skull and Crossbones) at a glance

Marks acute toxicity Categories 1–3 (the severe end); signal word “Danger.”
Applies by route: oral, dermal, and inhalation.
Cat 1–2 use “Fatal…” statements (H300/H310/H330); Cat 3 uses “Toxic…” (H301/H311/H331).
Category 4 (“Harmful…”) uses the exclamation mark (GHS07), not the skull.

In plain English

The “this can kill you” symbol. It flags chemicals so toxic that a small amount — swallowed, absorbed through skin, or inhaled — can be fatal or seriously poison you.

What the source says, in summary

H300: Fatal if swallowed. H310: Fatal in contact with skin. H330: Fatal if inhaled. H301/H311/H331: Toxic if swallowed / in contact with skin / if inhaled.
OSHA HCS — hazard statements (App C)Summarized, not quoted: read the source for its operative wording.

In context

A classification or labeling concept from the UN Globally Harmonized System, adopted into US law through OSHA's Hazard Communication Standard (29 CFR 1910.1200) and its appendices.

29 CFR 1910.1200

Where this is written in OSHA's rules

29 CFR 1910.1200 App CRead on eCFR / OSHA.gov

Read the related guide

Example

A pesticide with an oral LD50 of 30 mg/kg is acute toxicity Category 2, so it carries the skull-and-crossbones pictogram (GHS06), the signal word “Danger,” and H300, “Fatal if swallowed.” A less toxic Category 4 product would instead show the exclamation mark and H302, “Harmful if swallowed.”

Why it matters

The skull is the label's most urgent warning — it means a small exposure can kill. Under-classifying an acutely toxic chemical (using GHS07 where GHS06 belongs, or omitting the pictogram) hides a lethal hazard and is a serious HazCom classification violation under 1910.1200.

Skull (GHS06) vs. exclamation mark (GHS07) for toxicity

The skull (GHS06) is for the severe acute toxicity Categories 1–3 — “Fatal” or “Toxic.” The exclamation mark (GHS07) is for the mild Category 4 — “Harmful.” Same hazard class, but the category decides which pictogram (and how deadly the warning).

Acute toxicity under the skull pictogram (GHS06), by route

Route	Cat 1–2 (Fatal)	Cat 3 (Toxic)
Oral	H300	H301
Dermal	H310	H311
Inhalation	H330	H331

GHS06 (Skull and Crossbones): frequently asked questions

What does the skull and crossbones pictogram mean?: It marks severe acute toxicity — Categories 1, 2, and 3 by oral, dermal, or inhalation route — chemicals that can be fatal or toxic from a small, single exposure. The signal word is “Danger.”
When is the exclamation mark used instead of the skull?: For the least severe acute toxicity, Category 4 (“Harmful”). Categories 1–3 (“Fatal”/“Toxic”) use the skull-and-crossbones (GHS06); Category 4 uses the exclamation mark (GHS07).
Does the skull cover all three exposure routes?: Yes — it applies to oral (H300/H301), dermal (H310/H311), and inhalation (H330/H331) acute toxicity in Categories 1–3.

Free tools for this

GHS Label Generator SDS Gap Analyzer

Governing OSHA standards

OSHA Hazard Communication Standard (HazCom)OSHA HazCom Standard for Construction

More GHS terms

Acute Toxicity

A GHS health-hazard class for the harmful effects that follow a single dose, several doses within 24 hours, or a 4-hour inhalation exposure. Chemicals are sorted into categories by route (oral, dermal, inhalation) using LD50/LC50 cut-offs — Category 1 is the most toxic. OSHA's HazCom standard uses Categories 1–4.

Aspiration Hazard

A GHS health-hazard class for chemicals that can be fatal if swallowed and then enter the airways — directly or by vomiting — causing chemical pneumonia or lung injury. Thin, low-viscosity hydrocarbons (gasoline, kerosene, lamp oil) are the classic example. It is Category 1, with the health-hazard pictogram (GHS08) and signal word “Danger.”

Carcinogenicity

A GHS health-hazard class for chemicals that cause cancer or increase its incidence. GHS (and OSHA's HazCom standard) sorts carcinogens into Category 1A (known human carcinogen), 1B (presumed, from animal evidence), and Category 2 (suspected). Carcinogens carry the health-hazard pictogram (GHS08) and a hazard statement such as H350 (“May cause cancer”).

Chemicals Under Pressure

A physical-hazard class added by OSHA's 2024 HCS update (aligning with GHS Revision 7) for liquids or solids pressurized with a gas, held in pressure receptacles other than aerosol dispensers and not classified as gases under pressure. It is categorized by the flammability of its contents and always carries the gas-cylinder pictogram (GHS04) for the pressure hazard.

Classification

The process of evaluating the available scientific evidence for a chemical against the GHS criteria to decide whether it is hazardous and, if so, the hazard class and category of each effect. Classification is the first step in HazCom — its result determines every label element (pictogram, signal word, hazard and precautionary statements) and SDS content.

Corrosive to Metals

A GHS physical-hazard class for chemicals that, by chemical action, will materially damage or even destroy metals. It is a single category (Category 1), determined by corrosion-rate testing on steel and aluminum, and uses the corrosion pictogram (GHS05) with the hazard statement H290. It is a separate hazard from skin corrosion, even though both use GHS05.

Desensitized Explosives

A physical-hazard class added by OSHA's 2024 HCS update (GHS Revision 7) for solid or liquid explosives that have been phlegmatized — wetted or diluted — to suppress their explosive properties for safe transport and storage. It has four categories based on the corrected burning rate, and uses the flame pictogram (GHS02), not the exploding-bomb.

Globally Harmonized System (GHS)

An internationally agreed framework created by the United Nations (first adopted in 2003) that standardizes how chemical hazards are classified and communicated — using common hazard classes, pictograms, signal words (Danger / Warning), and coded hazard (H) and precautionary (P) statements on labels and safety data sheets. The US adopted GHS into law through OSHA's 2012 Hazard Communication Standard update.

Sources & verification

Reviewed by HazComFast against eCFR, OSHA.gov, NIOSH, and the Federal Register. Last reviewed 2026-10-05. This glossary is general information, not legal advice; OSHA State-Plan states (e.g. California, Michigan) may adopt stricter requirements.

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