The Global Harmonized System of Classification and Labeling of Chemicals (GHS or GHS, for the acronym Global Hharmonized System in English) offers a set of harmonized criteria on the hazard of chemicals. These criteria are used on labels and safety data sheets to report hazards. Because the International Chemical Substances Control Toolkit uses GHS hazard statements to identify the hazard zone as a first step in using the Toolkit in the workplace, it allows label statements to be translated into practical control measures.[1]​.

The decision to create the GHS originated from Chapter 19 of Agenda 21, approved at the United Nations Conference on Environment and Development (UNCED, 1992). Following intensive technical work to agree harmonized criteria, the GHS was adopted in 2002.

This technical work was coordinated and managed under the auspices of the Coordination Group for the Harmonization of Chemical Classification Systems (CG/HCCS) of the Inter-Agency Program for the Sound Management of Chemicals (IOMC). Those responsible for the technical issues necessary to complete the work were: the International Labor Organization (ILO) for hazard communication; the Organization for Economic Cooperation and Development (OECD) for the classification of health and environmental hazards; and the United Nations Subcommittee of Experts on the Transport of Dangerous Goods (UNSCETDG) and the ILO for physical hazards. The harmonized criteria allow:

Today, the GHS can be used worldwide. In its Implementation Plan adopted in Johannesburg on 4 September 2002, the World Summit on Sustainable Development (WSSD) encouraged countries to implement the new GHS as soon as possible. The GHS is currently maintained by a Subcommittee of the United Nations Economic and Social Council: the Subcommittee on the Globally Harmonized System of Classification and Labeling of Chemicals (GHS Subcommittee).

The implementation of the GHS has already begun: pilot countries in various regions of the world have incorporated the system into their national practices. With sufficient support for training and technical assistance, the widespread incorporation of both GHS and effective risk communication mechanisms into national legal and technical infrastructures is likely to occur. To achieve this goal, the UNITAR/ILO/IOMC GHS Capacity Building Program is undertaking partnership activities and offering support to help countries develop and implement the GHS. This work offers the opportunity to collaborate on the global implementation of the International Chemicals Control Toolkit.