Globally Harmonized System of Classification and Labelling of Chemicals

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The pictogram for harmful substances of the Globally Harmonized System of Classification and Labelling of Chemicals. GHS-pictogram-exclam.svg
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 standard managed by the United Nations that was set up to replace the assortment of hazardous material classification and labelling schemes previously used around the world. Core elements of the GHS include standardized hazard testing criteria, universal warning pictograms, and harmonized safety data sheets which provide users of dangerous goods with a host of information. The system acts as a complement to the UN Numbered system of regulated hazardous material transport. Implementation is managed through the UN Secretariat. Although adoption has taken time, as of 2017, the system has been enacted to significant extents in most major countries of the world. [1] This includes 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.



Before the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) was created and implemented, there were many different regulations on hazard classification in use in different countries, resulting in multiple standards, classifications and labels for the same hazard. Given the $1.7 trillion per year international trade in chemicals requiring hazard classification, the cost of compliance with multiple systems of classification and labeling is significant. Developing a worldwide standard accepted as an alternative to local and regional systems presented an opportunity to reduce cost and improve compliance. [2]

The GHS development began at the 1992 Rio Conference on Environment and Development by the United Nations [3] also called Earth Summit (1992) when the International Labour Organization (ILO), the Organisation for Economic Co-operation and Development (OECD), various governments and other stakeholders agreed 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". [4]

The universal standard for all countries was to replace all the diverse classification systems; however, it is not a compulsory provision of any treaty. The GHS provides a common infrastructure for participating countries to use when implementing a hazard classification and Hazard Communication Standard. [2]

Hazard classification

The GHS classification system is a complex system with data obtained from tests, literature, and practical experience. The hazards of a substanse is defined in classes of hazards and categories of severity.

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

Physical hazards

Substances or articles are assigned to 8 different hazard classes largely based on the United Nations Dangerous Goods System. [5] :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 (68 °F) 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 (199.4 °F). 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
  5. self-reactive substances , are 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.
  6. pyrophoric substance more colloquially described as spontaneously combusting substances are those solids or liquids 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.
  7. Self-heating substances A self-heating solids or liquids, other than a pyrophoric substance, is one 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.
  8. 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.
  9. Radioactive substances
  10. 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 (0.246063in) per year at a test temperature of 55 °C (131°F).
  11. Miscellaneous dangerous substances

Health hazards

Substitute substances

Sometimes companies are able to replace hazardous substances with substances featuring a reduced health risk. As an assistance to assess possible substitute substances, the Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA) has developed the Column Model. On the basis of just a small amount of information on a product, substitute substances can be evaluated with the support of this table. The current version from 2020 already includes the amendments of the 12th CLP Adaptation Regulation 2019/521. [7]

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

Per GHS, hazards need to be communicated:[ citation needed ]

Comprehensibility is challenging for a single culture and language, so global harmonization is complex. The GHS Purple Book includes a comprehensibility-testing instrument in Annex 6. Factors that were considered in developing the GHS communication tools include:[ citation needed ]

GHS label elements

The symbol for substances hazardous to the human health as implemented by the GHS. GHS-pictogram-silhouette.svg
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.[ citation needed ]

Safety data sheet

The safety data sheet or SDS (The GHS dropped the word "material" from material safety data sheet in its final revisions) 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 in perspective to the hazards, uses and risk management of the chemical product in the workplace. While there were some differences in existing industry recommendations and country specific requirements, there was agreement on a 16 section SDS to include the following headings in the order specified: [9]

  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. chemical 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 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, European Union and ANSI MSDS/SDS requirements. The SDS should provide a clear description of the data used to identify the hazards. A table comparing the content and format of a MSDS/SDS versus the GHS SDS is provided in Appendix A of the U.S. Occupational Safety and Health Administration (OSHA) GHS guidance. [10]


Current training procedures for Hazard Communication in the United States are more detailed than the GHS training recommendations. [2] Educating employees on the updated chemical and product classifications and related pictograms, signal words, hazard statements and precautionary measures at the level of detail by the national authority represents 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 the importation of products using only GHS labeling is permitted prior to its adoption in the United States and Canada, employers may need to begin employee training earlier than expected.


The United Nations goal was broad international adoption, and as of 2017, GHS has been adopted to varying degrees in nearly all major countries.

A flammable warning symbol on the back of a European Axe deodorant spray. GHS pictogram on back of Axe botte.jpg
A flammable warning symbol on the back of a European Axe deodorant spray.

GHS adoption by country:

  1. United Kingdom: Implemented under EU directive by REACH regulations, this may be subject to change due to Brexit.

See also

Related Research Articles

Toxicity Degree of harmfulness of substances

Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell (cytotoxicity) or an organ such as the liver (hepatotoxicity). By extension, the word may be metaphorically used to describe toxic effects on larger and more complex groups, such as the family unit or society at large. Sometimes the word is more or less synonymous with poisoning in everyday usage.

Safety data sheet System for cataloging information, potential hazards and instructions for safe use associated with a material or product

A safety data sheet (SDS), material safety data sheet (MSDS), or product safety data sheet (PSDS) is a document that lists information relating to occupational safety and health for the use of various substances and products. SDSs are a widely used system for cataloguing information on chemicals, chemical compounds, and chemical mixtures. SDS information may include instructions for the safe use and potential hazards associated with a particular material or product, along with spill-handling procedures. The older MSDS formats could vary from source to source within a country depending on national requirements; however, the newer SDS format is internationally standardized.

Hazard symbol Warning symbol on locations or products

Hazard symbols or warning symbols are recognisable symbols designed to warn about hazardous or dangerous materials, locations, or objects, including electric currents, poisons, and radioactivity. The use of hazard symbols is often regulated by law and directed by standards organizations. Hazard symbols may appear with different colors, backgrounds, borders, and supplemental information in order to specify the type of hazard and the level of threat. Warning symbols are used in many places in lieu of or addition to written warnings as they are quickly recognized and more commonly understood.

Chemical hazard Non-biological substance that has the potential to cause harm to life or health

A chemical hazard is a (non-biological) substance that has the potential to cause harm to life or health. Chemicals are widely used in the home and in many other places. Exposure to chemicals can cause acute or long-term detrimental health effects. There are many types of hazardous chemicals, including neurotoxins, immune agents, dermatologic agents, carcinogens, reproductive toxins, systemic toxins, asthmagens, pneumoconiotic agents, and sensitizers. In the workplace, exposure to chemical hazards is a type of occupational hazard. The use of protective personal equipment (PPE) may substantially reduce the risk of damage from contact with hazardous materials.

Process safety management

Process safety managementsystem is a regulation promulgated by the U.S. Occupational Safety and Health Administration (OSHA). A process is any activity or combination of activities including any use, storage, manufacturing, handling or the on-site movement of highly hazardous chemicals (HHCs) as defined by OSHA and the Environmental Protection Agency.

Dangerous goods Solids, liquids, or gases harmful to people, other organisms, property or the environment

Dangerous goods, abbreviated DG, are substances that when transported are a risk to health, safety, property or the environment. Certain dangerous goods that pose risks even when not being transported are known as hazardous materials.

Chloroprene Chemical compound

Chloroprene is the common name for 2-chlorobuta-1,3-diene (IUPAC name) with the chemical formula CH2=CCl−CH=CH2. Chloroprene is a colorless volatile liquid, almost exclusively used as a monomer for the production of the polymer polychloroprene, a type of synthetic rubber. Polychloroprene is better known as Neoprene, the trade name given by DuPont.

Directive 67/548/EEC

The Dangerous Substances Directive was one of the main European Union laws concerning chemical safety, until its full replacement by the new regulation CLP Regulation (2008), starting in 2016. It was made under Article 100 of the Treaty of Rome. By agreement, it is also applicable in the EEA, and compliance with the directive will ensure compliance with the relevant Swiss laws. The Directive ceased to be in force on 31 May 2015 and was repealed by Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on classification, labelling and packaging of substances and mixtures, amending and repealing Directives 67/548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006.

ADR (treaty) On transport of hazardous materials

ADR, formally the Agreement of 30 September 1957 concerning the International Carriage of Dangerous Goods by Road, is a 1957 United Nations treaty that governs transnational transport of hazardous materials. "ADR" is derived from the French name for the treaty: Accord relatif au transport international des marchandises Dangereuses par Route). Until 31 December 2020, the treaty was fully named European Agreement concerning the International Carriage of Dangerous Goods by Road. However, as the word "European" might have given the impression that the treaty was only open for accession to European states, an amendment was decided in the end of 2019.

Flammable liquid

A flammable liquid is a combustible liquid which can be easily ignited in air at ambient temperatures, i.e. it has a flash point at or below nominal threshold temperatures defined by a number of national and international standards organisations.

International Chemical Safety Cards (ICSC) are data sheets intended to provide essential safety and health information on chemicals in a clear and concise way. The primary aim of the Cards is to promote the safe use of chemicals in the workplace and the main target users are therefore workers and those responsible for occupational safety and health. The ICSC project is a joint venture between the World Health Organization (WHO) and the International Labour Organization (ILO) with the cooperation of the European Commission (EC). This project began during the 1980s with the objective of developing a product to disseminate the appropriate hazard information on chemicals at the workplace in an understandable and precise way.

Hazardous Materials Identification System Numerical hazard rating using colour coded labels

The Hazardous Materials Identification System (HMIS) is a numerical hazard rating that incorporates the use of labels with color developed by the American Coatings Association as a compliance aid for the OSHA Hazard Communication (HazCom) Standard.

Combustibility and flammability Ability to easily ignite in air at ambient temperatures

A combustible material is something that can burn in air. A combustible material is flammable if it ignites easily at ambient temperatures. In other words, a combustible material ignites with some effort and a flammable material catches fire immediately on exposure to flame.

CLP Regulation 2008 European Union regulation about chemicals

The CLP Regulation is a European Union regulation from 2008, which aligns the European Union system of classification, labelling and packaging of chemical substances and mixtures to the Globally Harmonised System (GHS). It is expected to facilitate global trade and the harmonised communication of hazard information of chemicals and to promote regulatory efficiency. It complements the 2006 Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) Regulation and replaces the current system contained in the Dangerous Substances Directive (67/548/EEC) and the Dangerous Preparations Directive (1999/45/EC).

Hazard statements form part of the Globally Harmonized System of Classification and Labelling of Chemicals (GHS). They are intended to form a set of standardized phrases about the hazards of chemical substances and mixtures that can be translated into different languages. As such, they serve the same purpose as the well-known R-phrases, which they are intended to replace.

Hazard pictograms form part of the international Globally Harmonized System of Classification and Labelling of Chemicals (GHS). Two sets of pictograms are included within the GHS: one for the labelling of containers and for workplace hazard warnings, and a second for use during the transport of dangerous goods. Either one or the other is chosen, depending on the target audience, but the two are not used together. The two sets of pictograms use the same symbols for the same hazards, although certain symbols are not required for transport pictograms. Transport pictograms come in wider variety of colors and may contain additional information such as a subcategory number.

The Hazard Communication Standard requires employers in the United States to disclose toxic and hazardous substances in workplaces. This is related to the Worker Protection Standard.

Chemical storage

Chemical storage is the storage of controlled substances or hazardous materials in chemical stores, chemical storage cabinets, or similar devices.

Pipe marking is the used to identify the contents, properties and flow direction of fluids in piping. Marking assists personnel to identify the correct pipes for operational, maintenance or emergency response purposes. Pipes are marked by labels, typically color coded, to identify the use, contents and flow direction.

Chemicals as elements, compounds, mixtures, solutions and emulsions are very widely used and transported in the modern industrial society. Of necessity, they are also used in schools, Universities and other training facilities to educate pupils in their safe use and handling and also are commonly used in domestic situations for cleaning, garden maintenance and DIY.


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