Globally Harmonized System of Classification and Labelling of Chemicals

The pictogram for harmful substances of the Globally Harmonized System of Classification and Labelling of Chemicals.

The Globally Harmonized System of Classification and Labelling of Chemicals (GHS) is an internationally agreed-upon system, created by the United Nations beginning in 1992 and as of 2015 is not yet fully implemented in many countries. It was designed to replace the various classification and labelling standards used in different countries by using consistent criteria on a global level. It supersedes the relevant system of the European Union, which has implemented the United Nations' GHS into EU law as the CLP Regulation and United States Occupational Safety and Health Administration standards.


The Globally Harmonized System of Classification and Labelling of Chemicals (GHS) was developed beginning at the United Nations[1] Rio Conference in 1992, when the International Labour Organization (ILO), the Organisation for Economic Co-operation and Development (OECD), various governments and other stakeholders met at a United Nations conference. Before it was created and implemented, there were many different regulations on hazard classification in use in different countries. While those systems may have been similar in content and approach, they resulted in multiple standards, classifications and labels for the same hazard. Given the extent of international trade in chemicals and the potential impact on neighboring countries when controls are not implemented, countries determined that a worldwide approach was necessary.

The GHS was designed as one universal standard for all countries to follow and to replace all the diverse classification systems; however, it is not compulsory under UN law. The system provides the infrastructure for participating countries to implement a hazard classification and hazard communication standard, which many less economically developed countries would not have had the money to create themselves. In the longer term, the GHS is expected to improve knowledge of the chronic health hazards of chemicals and encourage a move towards the elimination of hazardous chemicals, especially carcinogens, mutagens and reproductive toxicants, or their replacement with less hazardous ones.

The final "Globally Harmonized System (GHS) for classification and labelling" standard was created at the 1992 Rio Conference on Environment and Development with the statement that "A globally harmonized hazard classification and compatible labelling system, including material safety data sheets and easily understandable symbols, should be available if feasible, by the year 2000". An illustration shows the timeline of GHS and the progress needed to completely put GHS into place.[2]

Hazard classification

The GHS classification system is a complex system with data obtained from tests, literature, and practical experience.

The main elements of the hazard classification criteria are summarized below:

Physical hazards

Substances or articles are assigned to 9 different hazard classes largely based on the United Nations Dangerous Goods System.[3]:59–60 Additions and changes have been necessary since the scope of the GHS includes all target audiences.

  1. Explosives, which are assigned to one of six subcategories depending on the type of hazard they present, as used in the UN Dangerous Goods System.
  2. Gases are category 1 flammable if they start to flame in a range in air at 20 °C and a standard pressure of 101.3 kPa. Category 2 is Non flammable and non toxic gases, and category 3 is toxic gases. Substances and mixtures of this hazard class are assigned to one of two hazard categories on the basis of the outcome of the test or calculation method.
  3. A flammable liquid is a liquid with a flash point of not more than 93 °C. Substances and mixtures of this hazard class are assigned to one of four hazard categories on the basis of the flash point and boiling point. A pyrophoric liquid is a liquid that, even in small quantities, is liable to ignite within five minutes after coming into contact with air. Substances and mixtures of this hazard class are assigned to a single hazard category on the basis of the outcome of the UN Test N.3.
  4. A flammable solid is one that is readily combustible or may cause or contribute to fire through friction. Readily combustible solids are powdered, granular, or pasty substances which are dangerous if they can be easily ignited by brief contact with an ignition source, such as a burning match, and if the flame spreads rapidly. it is further divided into
    • flammable solids,
    • polymerizing substances and
    • self-reactive substances, i.e., thermally unstable solids liable to undergo a strongly exothermic thermal decomposition even without participation of oxygen (air) other than materials classified as explosive, organic peroxides or as oxidizing.
    Spontaneously combusting solids or pyrophoric solids are solids that, even in small quantities, are liable to ignite within five minutes after coming into contact with air. Substances and mixtures of this hazard class are assigned to a single hazard category on the basis of the outcome of the UN Test N.2. Self-heating substances are solids or liquids, other than a pyrophoric substance, which, by reaction with air and without energy supply, are liable to self-heat. Substances and mixtures of this hazard class are assigned to one of two hazard categories on the basis of the outcome of the UN Test N.4. Substances which on contact with water emit flammable gases are liable to become spontaneously flammable or to give off flammable gases in dangerous quantities. Substances and mixtures of this hazard class are assigned to one of three hazard categories on the basis of the outcome of UN Test N.5, which measures gas evolution and speed of evolution. Flammable aerosols can be classified as Class 1 or Class 2 if they contain any component, which is classified as flammable.
  5. Oxidizing substances and organic peroxides contain
    • category 1: oxidizing substances and
    • category 2: organic peroxides, organic liquids or solids that contain the bivalent -O-O- structure and may be considered a derivative of hydrogen peroxide, where one or both of the hydrogen atoms have been replaced by organic radicals. The term also includes organic peroxide formulations (mixtures).
    Substances and mixtures of this hazard class are assigned to one of seven 'Types', A to G, on the basis of the outcome of the UN Test Series A to H.
  6. Toxic and infectious substances
  7. Radioactive substances
  8. Substances corrosive to metal are substances or mixtures that by chemical action will materially damage or even destroy metals. These substances or mixtures are classified in a single hazard category on the basis of tests (Steel: ISO 9328 (II): 1991 - Steel type P235; Aluminum: ASTM G31-72 (1990) - non-clad types 7075-T6 or AZ5GU-T66). The GHS criteria are a corrosion rate on steel or aluminum surfaces exceeding 6.25 mm per year at a test temperature of 55 °C.
  9. Miscellaneous dangerous substances which includes environmentally dangerous substances

Health hazards

Environmental hazards

Classification of mixtures

The GHS approach to the classification of mixtures for health and environmental hazards is also complex. It uses a tiered approach and is dependent upon the amount of information available for the mixture itself and for its components. Principles that have been developed for the classification of mixtures, drawing on existing systems such as the European Union (EU) system for classification of preparations laid down in Directive 1999/45/EC. The process for the classification of mixtures is based on the following steps:

  1. Where toxicological or ecotoxicological test data are available for the mixture itself, the classification of the mixture will be based on that data;
  2. Where test data are not available for the mixture itself, then the appropriate bridging principles should be applied, which uses test data for components and/or similar mixtures;
  3. If (1) test data are not available for the mixture itself, and (2) the bridging principles cannot be applied, then use the calculation or cutoff values described in the specific endpoint to classify the mixture.

Testing requirements

The GHS document does not include testing requirements for substances or mixtures. In fact, one of the main goals of the GHS is to reduce the need for animal testing. The GHS criteria for determining health and environmental hazards are test method neutral, allowing different approaches as long as they are scientifically sound and validated according to international procedures and criteria already referred to in existing systems. Test data already generated for the classification of chemicals under existing systems should be accepted when classifying these chemicals under the GHS, thereby avoiding duplicative testing and the unnecessary use of test animals. The GHS physical hazard criteria are linked to specific UN test methods. It is assumed that mixtures will be tested for physical hazards.

Hazard communication

After the substance or mixture has been classified according to the GHS criteria, the hazards need to be communicated. As with many existing systems, the communication methods incorporated in GHS include labels and SDS’s. The GHS attempts to standardize hazard communication so that the intended audience can better understand the hazards of the chemicals in use. The GHS has established guiding principles:

Comprehensibility is challenging for a single culture and language. Global harmonization has numerous complexities. Some factors that affected the work include:

These factors were considered in developing the GHS communication tools. The GHS Purple Book includes a comprehensibility-testing instrument in Annex 6.

GHS label elements

The symbol for substances hazardous to the human health as implemented by the GHS.

The standardized label elements included in the GHS are:

The additional label elements included in the GHS are:

GHS label format

The GHS includes directions for application of the hazard communication elements on the label. In particular, it specifies for each hazard, and for each class within the hazard, what signal word, pictogram, and hazard statement should be used. The GHS hazard pictograms, signal words and hazard statements should be located together on the label. The actual label format or layout is not specified in the GHS. National authorities may choose to specify where information should appear on the label or allow supplier discretion. There has been discussion about the size of GHS pictograms and that a GHS pictogram might be confused with a transport pictogram or "diamond". Transport pictograms are different in appearance than the GHS pictograms. Annex 7 of the Purple Book explains how the GHS pictograms are expected to be proportional to the size of the label text so that generally the GHS pictograms would be smaller than the transport pictograms.

GHS material safety data sheet or safety data sheet

The safety data sheet (The GHS has dropped the word "material" from material safety data sheet. It will now be called the safety data sheet or SDS) is specifically aimed at use in the workplace. It should provide comprehensive information about the chemical product that allows employers and workers to obtain concise, relevant and accurate information that can be put in perspective with regard to the hazards, uses and risk management of the chemical product in the workplace. The SDS should contain 16 sections. While there were some differences in existing industry recommendations, and requirements of countries, there was widespread agreement on a 16 section SDS that includes the following headings in the order specified:

  1. Identification
  2. Hazard(s) identification
  3. Composition/ information on ingredients
  4. First-aid measures
  5. Fire-fighting measures
  6. Accidental release measures
  7. Handling and storage
  8. Exposure control/ personal protection
  9. Physical and chemical properties
  10. Stability and reactivity
  11. Toxicological information
  12. Ecological information
  13. Disposal considerations
  14. Transport information
  15. Regulatory information
  16. Other information.

The primary difference between the GHS requirements in terms of headings and sections and the international industry recommendations is that sections 2 and 3 have been reversed in order. The GHS SDS headings, sequence and content are similar to the ISO, EU and ANSI MSDS/SDS requirements. The SDS should provide a clear description of the data used to identify the hazards. There is a table comparing the content and format of a current MSDS/SDS versus the GHS SDS provided in Appendix A of the OSHA GHS guidance document available.[6]


Current training procedures for Hazard Communication in the United States are more detailed than the GHS training recommendations. Therefore, educating employees on the updated chemical and product classifications and related pictograms, signal words, hazard statements and precautionary measures will represent the greatest training challenge. Training will be a key component of the overall GHS approach and should incorporate information as it is introduced into the workplace. Employees and emergency responders will need to be trained on all new program elements, from hazard statements to pictograms. Bear in mind, if products are imported from countries that implement GHS prior to the United States and Canada, employee training may need to begin earlier than expected.


The adoption of the GHS is expected to facilitate international trade by increasing consistency between the laws in different countries that currently have different hazard communication requirements. There is no set international implementation schedule for the GHS. The goal of the United Nations was broad international adoption by 2008. Different countries will require different time frames to update current regulations or implement new ones.

GHS adoption by country:

See also


  1. Health and Safety Executive (n.d.). "UK Government HSE website". UK Government.
  2. "GHS: What's Next? |". Retrieved 2015-06-19.
  3. UN Recommendations on the Transport of Dangerous Goods - Model Regulations, Rev. 19 Volume I 2015, United Nations Economic Commission for Europe, retrieved 6 November 2015
  4. "Globally Harmonized System of Classification and Labelling of Chemicals (GHS) - second revised edition" (PDF). United Nations. Retrieved 2012. Check date values in: |access-date= (help)
  5. "GHS pictograms - Transport - UNECE". Retrieved 2015-06-19.
  6. "Globally Harmonized System of Classification and Labelling of Chemicals - GHS". Retrieved 2015-06-18.
  7. Hazardous chemicals
  8. Implementation of GHS in Brazil
  9. Implementation of the GHS in Canada UN Committee of Experts on the Transport of Dangerous Goods and on the Globally Harmonized System of Classification and Labelling of Chemicals, 4 December 2012
  10. 1 2 3 GHS in China, Korea and Japan 2011
  11. European Commission CLP/GHS - Classification, labelling and packaging of substances and mixtures
  12. GHS in Turkey
  13. GHS in Malaysia
  14. GHS in Philippines
  15. GHS in Taiwan
  16. GHS in Thailand
  17. GHS in Vietnam
  18. Hazard Communication OSHA, n.d.
  19. Hazard Communication System Final Rule - Fact Sheet OSHA, n.d.


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