GHS Hazard Class and Hazard Category

Little Pro on 2016-01-06

GHS describes the nature and severity of a chemical hazard by hazard class and hazard category:

  • GHS hazard class represents the nature of a chemical hazard, i.e., flammable liquids, carcinogen.
  • GHS hazard category is the division of criteria within each hazard class. For example, hazard class flammable liquids can be divided into 4 categories among which flammable liquids category 1 represents the most severe hazard.

There are 29 GHS hazard classes in total in UN GHS Rev. 6. They are used to describe 3 main types of chemical hazards: physical hazards, health hazards and environmental hazards. If you wish to find hazard statements and signal word for each hazard category, please use our hazard statement and signal word finder.

Physical Hazards(17 classes)
  • Explosives
  • Flammable Gases
  • Aerosols
  • Oxidizing Gases
  • Gases Under Pressure
  • Flammable Liquids
  • Flammable Solids
  • Self-Reactive Substances
  • Pyrophoric Liquids
  • Pyrophoric Solids
  • Self-Heating Substances
  • Substances which, in contact with water emit flammable gases
  • Oxidizing Liquids
  • Oxidizing Solids
  • Organic Peroxides
  • Corrosive to Metals
  • Desensitized explosives[Added in GHS Rev. 6]
Health Hazards(10 classes)
  • Acute Toxicity (Oral/Dermal/Inhalation)
  • Skin Corrosion/Irritation
  • Serious Eye Damage/Eye Irritation
  • Respiratory or Skin Sensitization
  • Germ Cell Mutagenicity
  • Carcinogenicity
  • Reproductive Toxicology
  • Target Organ Systemic Toxicity - Single Exposure
  • Target Organ Systemic Toxicity - Repeated Exposure
  • Aspiration Toxicity
Environmental Hazards(2 classes)
  • Hazardous to Aquatic Environment (Acute/Chronic)
  • Hazardous to the Ozone Layer

Determination of GHS Hazard Class and Hazard Category

GHS has provided standard chemical classification criteria which are used to determine the hazard class and hazard category of a chemical. The picture below is an example of GHS classification criteria for flammable liquids. A liquid with a flash point between 23 and 60 Celsius degrees will be classified as flammable liquid category 3. A liquid with a flash point above 93 Celsius degrees does not meet GHS classification criteria and will not be regarded as a hazardous chemical.

GHS Hazard Class

Download GHS Classification Criteria

Standard hazard pictograms, hazard statements and precautionary statements will be assigned once the hazard class and hazard category of a chemical has been determined. (see example below).

GHS Hazard Class

Adoption of GHS Hazard Class & Hazard Category in Individual Countries.

GHS allows individual countries or regions to choose which hazard classes or hazard categories to implement to meet their domestic needs. For example, EU has not adopted flammable liquids category 4. The United States has not adopted Hazardous to the Ozone Layer yet. This is often called GHS Building Block approach.

Reference & Resources

Advanced GHS Readings

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 Tags: Topics - GHSGHS Basics and Tutorials