GHS reference

GHS Reference: Hazard Statements, Precautionary Statements and Pictograms

The GHS is the UN's Globally Harmonized System of Classification and Labelling of Chemicals. It gives every hazardous chemical a standard set of hazard classes, label elements and safety data sheet headings, so a worker in Houston, Hamburg or Hanoi reads the same warning in the same way. This section covers every code and symbol in the system, using the data from UN GHS Revision 10.

Reference only. This section explains the system. The classification and label for a real product come from the supplier's safety data sheet, which can differ from the generic information here.

What the GHS is and why it exists

Before the GHS, each country had its own rules. A drum of solvent might be labelled "flammable" in one country, "highly flammable" in another, and carry different symbols in a third. That caused confusion for workers and slowed international trade. The UN published the first GHS edition in 2003, and it has been revised roughly every two years since. Revision 10 is the edition behind the codes on this site.

The GHS does two jobs. First, it sets out classification criteria: tests and thresholds that decide whether a substance is, for example, a Category 2 flammable liquid or a Category 1 skin corrosive. Second, it sets out communication elements: the labels and safety data sheets that pass that classification on to the people who use the chemical.

The GHS is guidance, not law. Countries adopt it in their own way, often in the "building block" approach that lets them leave out some hazard classes or categories. In the United States it is implemented through OSHA's Hazard Communication Standard, in the European Union through the CLP Regulation, and in Canada through WHMIS. That is why you may see small differences between labels from different regions.

How a GHS label works

A compliant label for a hazardous chemical has six elements. Learn to find them in this order and you can read any label quickly.

Label element	What it tells you
Product identifier	The name of the chemical or product, matching the name on the safety data sheet. For a mixture it can also list the ingredients that drive the hazard.
Signal word	"Danger" for the more severe hazards or "Warning" for the less severe ones. Only one is used. Some low-hazard categories have none.
Pictograms	Black symbols on a white background inside a red diamond border. Each stands for a group of hazards, such as flame, corrosion or skull and crossbones.
Hazard statements	Standard sentences that describe the nature and severity of the hazard, each with an H-code. Example: "Highly flammable liquid and vapor."
Precautionary statements	Standard advice on preventing or responding to exposure or an incident, each with a P-code, covering prevention, response, storage and disposal.
Supplier identification	Name, address and telephone number of the manufacturer, importer or other responsible party, so you know who to contact for more information.

A label is only a summary. The full picture, including first aid, personal protective equipment, exposure limits and spill response, is in the 16-section safety data sheet. If you have an SDS and want it explained, try the AI SDS analyzer.

How hazards are organised

The GHS groups hazards into three families: physical hazards (fire, explosion, pressure, reaction with metals), health hazards(toxicity, corrosion, irritation, sensitization, cancer, reproductive effects) and environmental hazards (harm to aquatic life and the ozone layer). Within each family a hazard class names the type of hazard, and a category within the class gives its severity, where Category 1 is generally the most severe.

Each class and category maps to a hazard statement. H-codes follow a pattern: H2xx for physical hazards, H3xx for health hazards and H4xx for environmental hazards. The numbers are only an index and do not show severity on their own. A hazard class, category and the pictogram and signal word that go with it tell you how serious the hazard is.

Explore the GHS reference

Hazard statements (H-codes)

What each H-code says, the hazard class and category behind it, and the pictogram and signal word that go with it. 106 current codes.

Precautionary statements (P-codes)

Prevention, response, storage and disposal advice, and which hazards call for each statement. 133 current codes.

Pictograms

The nine red-diamond symbols, what each represents, and how OSHA, the UN GHS and transport labels differ.

Hazard classes

The 35 hazard classes used to classify chemicals, with their categories and codes.

Signal words

Danger versus Warning: what the word means and how it is chosen.

The nine GHS pictograms

Select a pictogram for the hazard classes it covers and the chemicals that carry it.

Common questions

What does GHS stand for?

GHS stands for the Globally Harmonized System of Classification and Labelling of Chemicals, an international system created by the United Nations so that hazardous chemicals are classified and labelled the same way in every country that adopts it.

Is the GHS a law?

No. The GHS is a UN guidance document sometimes called the Purple Book. It becomes binding only when a country or region adopts it into its own rules, for example OSHA's Hazard Communication Standard in the United States, CLP in the European Union and WHMIS in Canada. National versions can differ in which parts they adopt.

What are the parts of a GHS label?

A GHS label has six core elements: a product identifier, a signal word (Danger or Warning), hazard pictograms, hazard statements, precautionary statements, and the name, address and phone number of the supplier.

What is the difference between H-codes and P-codes?

H-codes identify the hazard, such as H225 for a highly flammable liquid and vapor. P-codes give advice on how to prevent, respond to, store or dispose of the product safely. A label lists the H-codes that apply to the product and the P-codes that go with them.

https://pubchem.ncbi.nlm.nih.gov/ghs/ghscode_10.txt (retrieved 2026-10-12)