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 safety data sheets which provide users of dangerous goods relevant information with consistent organization. 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. 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 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 costs and improve compliance.
The GHS development began at the 1992 Rio Conference on Environment and Development by the United Nations, 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".
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.
The GHS classification system defines and classifies the physical, health, and/or environmental hazards of a substance. Each category within the classifications has associated pictograms to be used when applied to a material or mixture.
As of the 10th revision of the GHS, substances or articles are assigned to 17 different hazard classes largely based on the United Nations Dangerous Goods System.
The GHS approach to the classification of mixtures for health and environmental hazards 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:
Companies are encouraged 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.
The GHS generally defers to the United States Environmental Protection Agency and OECD to provide and verify toxicity testing requirements for substances or mixtures. Overall, 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.
For physical hazards, the test criteria are linked to specific UN test methods.
Per GHS, hazards need to be communicated:
Comprehensibility is a significant consideration in GHS implementation. The GHS Purple Book includes a comprehensibility-testing instrument in Annex 6. Factors that were considered in developing the GHS communication tools include:
The standardized label elements included in the GHS are:
The additional label elements included in the GHS are:
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. National authorities may choose to specify where information should appear on the label, or to allow supplier discretion in the placement of GHS information.
The diamond shape of GHS pictograms resembles the shape of signs mandated for use by the United States Department of Transportation. To address this, in cases where a pictogram would be required by both the Department of Transportation and the GHS indicating the same hazard, only the Transportation pictogram is to be used.
Safety data sheets or SDS are specifically aimed at use in the workplace. Safety data sheets take precedence over and are intended to replace the previously used material safety data sheets (MSDS), which did not have a standard layout and section format. 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. Compared to the differences found between manufacturers in MSDS, SDS have specific requirements to include the following headings in the order specified:
The primary difference between the GHS and previous 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. 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.
Current training procedures for hazard communication in the United States are more detailed than the GHS training recommendations. Training is a key component of the overall GHS approach. Employees and emergency responders must be trained on all program elements, though there has been confusion among these groups of workers in the implementation process regarding which training elements have changed and are required to maintain regulatory compliance.
The United Nations goal was for broad international adoption of the system, and as of 2017, the GHS had been adopted to varying degrees in many major countries. Smaller economies continue to develop regulations to implement the GHS throughout the 2020s.