The Globally Harmonized System was initiated at the UN Conference on the Environment and Development in Rio de Janeiro in 1992. It aims, amongst other goals, to harmonize the classification and the hazard communication elements of chemicals (labeling and safety data sheets). The first version became available in 2003 in the form of the so called purple book (compared to the orange book for transportation). Regular updates should take place every 2 years. GHS harmonizes most classification criteria for supply and transportation and is based on the intrinsic properties of substances. GHS allows individual countries or regions to implement building blocks at their own discretion. The building blocks, however, may not be altered. Additionally there is room for Competent Authority Options and special limits for the communication of components in mixtures.

Reasons for the development of GHS:

• Growing international trade
• Different requirements for labeling of chemicals
• Different classifications of identical products in different countries
• Requirement for an international safety standard

GHS is the acronym for the Globally Harmonized System of Classification and Labelling of Chemicals, known in the hazard communication community as the “Purple Book.”  GHS was born from an international mandate adopted at the 1992 “Earth Summit,” the United Nations Conference on Environment and Development (UNCED).  Several updates to the "Purple Book" have been made since its first publication in February 2003, with the most recent publication being the second revised edition in October 2007.

Given the expansion of a global economy and international trade, the GHS seeks to achieve global unification of chemical classifications. The GHS defines the physical, health and environmental hazards of chemicals by means of classification endpoints.  This system provides the foundation for developing countries to create regulations ensuring the safe use of chemicals by workers, consumers, emergency responders and the public.  For countries with established regulatory requirements, the existing laws and regulations are similar, but there are still enough differences to currently require multiple Safety Data Sheets and labels for the same product when it is sold in multiple regulatory environments.  

Adoption of the GHS for these countries means reducing the variation among independent classification systems and moving towards global hazard communication. 

There is no international implementation schedule for the GHS. Instead, implementation will be staggered globally, adopted on a country-by-country basis. Countries with no system in place to communicate hazards will have the easiest time adopting the GHS. Countries with existing systems will need to consider phase-in or building-block strategies for transition from current requirements to the new GHS requirements. 

In the United States, for example, four governing bodies or competent authorities have regulations which are affected by the GHS: OSHA, EPA, DOT and CPSC. Several countries have published GHS classifications in preparation for implementation. Japan’s efforts include the development of an international GHS classification list which classifies approximately 1,500 chemicals. The European Union includes a list of classifications in its Proposal for a Regulation of the European Parliament and of the Council on classification, labelling and packaging of substances and mixtures, and amending Directive 67/548/EEC and Regulation (EC) no 1907/2006. In December 2007, New Zealand released their list of GHS classifications which are accessible via a web-based search. For Australia, there is a short list of GHS classifications provided by the Department of Health and Ageing from Priority Existing Chemical Assessment reports. Taiwan published a list of Hazardous and Harmful Substances which will require specific labeling provisions in coordination with GHS under the Rules on Labeling and Hazard Communication of Hazardous and Harmful Substances. 

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