Understanding chemical hazards starts with understanding the standardized language used to describe them. Under the Globally Harmonized System (GHS), hazard communication ensures that workers, employers, and emergency responders receive consistent and clear safety information no matter where chemicals are manufactured or used. In the United States, OSHA implements GHS principles through the Hazard Communication Standard (HCS), 29 CFR 1910.1200.
One of the most important components of this system is the hazard statement.
GHS uses a uniform approach to classify chemicals and communicate hazards on labels and Safety Data Sheets (SDS). Every U.S.-compliant GHS label must contain six specific elements that work together to communicate risk:
Product Identifier
Supplier Information
Signal Word (“Danger” or “Warning”)
Hazard Pictograms
Hazard Statements
Precautionary Statements
Each element has a purpose. The hazard statement is the part of the label that clearly communicates what hazard is present and how severe it is. Hazard statements guide which pictograms appear, which signal word is used, and what precautions apply.
A hazard statement is a required, standardized phrase that describes the type and severity of a chemical hazard. It is not a general warning or a guideline. It is tied directly to the chemical’s official classification.
GHS hazard statements must:
Appear exactly as written in OSHA’s Hazard Communication Standard
Be included on all shipped container labels
Be listed in Section 2 of the SDS
Match the chemical’s GHS hazard class and category
Communicate hazards in clear, universally recognized language
These statements remove ambiguity and make hazards easy for workers to understand.
To determine which hazard statement applies to a chemical, you need to understand its GHS classification. This classification is normally done by the manufacturer or importer, but employers should understand the basics so they can read labels correctly and maintain compliance.
Two elements determine the hazard statement:
1. GHS Hazard Class - This identifies the type of hazard, such as flammable liquid, skin irritation, respiratory sensitization, or carcinogenicity. A chemical can have several hazard classes.
2. GHS Hazard Category - This identifies the severity of the hazard within the class. Categories range from 1 (most severe) to 4 (least severe), depending on the hazard class.
Each class and category pairing has one specific hazard statement. OSHA requires that hazard statements be used exactly as published with no rewriting or combining.
For U.S. workplaces, the required hazard statements appear in:
Section 2: Hazard Identification of the supplier’s SDS
The manufacturer’s or importer’s GHS-compliant shipped label
If a chemical is transferred to a secondary container for use beyond immediate use, employers must use the same hazard statements shown in Section 2 of the SDS or on the shipped label.
Businesses that want additional context can review OSHA Hazard Communication Standard Appendix C for the official U.S. list of required hazard statements or the UN GHS “Purple Book” or global variations. OSHA’s standard is based on GHS Revision 3.
GHS hazard statements follow a simple numbering system that helps you understand the type of hazard a chemical presents. Each statement begins with the letter H and a three-digit number. The first digit identifies the general hazard group.
H200–H299 identify physical hazards such as flammability, explosion, oxidizing ability, and reactivity.
H300–H399 identify health hazards such as toxicity, irritation, cancer effects, and organ toxicity.
H400–H499 identify environmental hazards such as aquatic toxicity.
For U.S. businesses, the important point is which groups OSHA enforces. Physical hazard statements in the H2 series and health hazard statements in the H3 series are required. Environmental hazard statements in the H4 series may appear on SDSs from global suppliers but are not required for U.S. workplace labeling except for the ozone depletion statement H420.
Some international documents may reference codes such as EUH001. These are specific to the European Union and are not used under OSHA’s Hazard Communication Standard.
Understanding this structure helps you interpret hazard statements more easily and identify which ones apply to OSHA compliance.
Flammable liquid and vapour
Combustible liquid
Flammable solid
Pressurized container: may burst if heated
May react explosively even in the absence of air
May react explosively even in the absence of air at elevated pressure and/or temperature
May ignite spontaneously if exposed to air
Heating may cause an explosion
Self-heating; may catch fire
These statements describe acute toxicity, irritation, sensitization, carcinogenicity, reproductive toxicity, and organ effects.
Causes serious eye damage
Causes serious eye irritation
Causes eye irritation
Fatal if inhaled
Toxic if inhaled
Harmful if inhaled
May be harmful if inhaled
May cause allergy or asthma symptoms or breathing difficulties if inhaled
H335
Suspected of causing genetic defects
These statements address aquatic toxicity and impacts to the environment. OSHA does not enforce most environmental hazard statements, but you may see them on SDSs from global suppliers.
Hazard statements marked with * are global GHS hazard statements not adopted under OSHA's Hazard Communication Standard. These may appear on SDSs from international suppliers but are not required for U.S. workplace labeling.
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