About GHS (Globally Harmonized System)

What is GHS?

GHS stands for the “Globally Harmonized System of Classification and Labelling of Chemicals”. GHS is a system that defines and classifies the hazards of chemical products, and communicates heath and safety information on labels and material safety data sheets (called Safety Data Sheets, or SDSs, in GHS). The goal is that the same set of rules for classifying hazards, and the same format and content for labels and safety data sheets (SDS) will be adopted and used around the world. An international team of hazard communication experts developed GHS.

Why is global harmonization necessary?

Currently many different countries have different systems for classification and labelling of chemical products. In addition, several different systems can exist even within the same country. This situation has been expensive for governments to regulate and enforce, costly for companies who have to comply with many different systems, and confusing for workers who need to understand the hazards of a chemical in order to work safely.

GHS promises to deliver several distinct benefits. Among them are:

  • promoting regulatory efficiency
  • facilitating trade
  • easing compliance
  • reducing costs
  • providing improved, consistent hazard information
  • encouraging the safe transport, handling and use of chemicals
  • promoting better emergency response to chemical incidents, and
  • reducing the need for animal testing

What is the scope of GHS?

The GHS system covers all hazardous chemicals and may be adopted to cover chemicals in the workplace, transport, consumer products, pesticides and pharmaceuticals. The target audiences for GHS include workers, transport workers, emergency responders and consumers.

What are the two major elements in GHS?

The two major elements of GHS are:

1. Classification of the hazards of chemicals according to the GHS rules:

GHS provides guidance on classifying pure chemicals and mixtures according to its criteria or rules.

2. Communication of the hazards and precautionary information using Safety Data Sheets and labels:

Labels – With the GHS system, certain information will appear on the label. For example, the chemical identity may be required. Standardized hazard statements, signal words and symbols will appear on the label according to the classification of that chemical or mixture. Precautionary statements may also be required, if adopted by your regulatory authority.

Safety Data Sheets (SDS) – The GHS SDS has 16 sections in a set order, and information requirements are prescribed.

What are some key terms in the GHS Vocabulary?

SDS – Safety Data Sheet. SDS is the term used by GHS for Material Safety Data Sheet (MSDS).
Hazard group – While not given a formal definition, GHS divides hazards into three major groups – health, physical and environmental.
Class – Class is the term used to describe the different hazards. For example, “Gases under Pressure” is an example of a class in the physical hazards group.
Category – Category is the name used to describe the sub-sections of classes. For example, Self-Reactive Chemicals have 7 categories. Each category has rules or criteria to determine what chemicals are assigned to that category.
Hazard Statement – For each category of a class, a standardized statement is used to describe the hazard. For example, the hazard statement for chemicals which meet the criteria for the class Self-heating substances and mixtures, Category 1 is “Self-heating; may catch fire”. This hazard statement would appear both on the label and on the SDS.
Signal word – There are two signal words in the GHS system - Danger and Warning. These signal words are used to communicate the level of hazard on both the label and the SDS. The appropriate signal word to use is set out by the classification system. For example, the signal word for Self-heating substances and mixtures, Category 1 is “Danger” while “Warning” is used for the less serious Category 2. There are categories where no signal word is used.
Pictogram – Pictogram refers to the GHS symbol on the label and SDS. Not all categories have a symbol associated with them.

What is meant by the GHS hazard groupings and “building block” concept?

Within the GHS classification system, there are three major hazard groups:

  • Physical hazards,
  • Health hazards, and
  • Environmental hazards.

Within each of these hazard groups there are “classes” and “categories”. Each of these parts is called a “building block”. Each country can determine which building blocks of the GHS system it will use in their different sectors (workplace, transportation, consumers). Once the building blocks are chosen, the corresponding GHS rules for classification and labels must be used.

What are the classes within the Health hazard group?

Criteria for classifying chemicals have been developed for the following health hazard classes:

  • acute toxicity
  • skin corrosion/irritation
  • serious eye damage/eye irritation
  • respiratory or skin sensitization
  • germ cell mutagenicity
  • carcinogenicity
  • reproductive toxicity
  • specific target organ toxicity – single exposure
  • specific target organ toxicity – repeated exposure, and
  • aspiration hazard

In addition, there are specific classification rules for chemical mixtures for each health hazard class.

What are the classes within the Physical hazard group?

Criteria for classifying chemicals have been developed for the following physical hazard classes:

  • explosives
  • flammable gases
  • flammable aerosols
  • oxidizing gases
  • gases under pressure
  • flammable liquids
  • flammable solids
  • self-reactive substances and mixtures
  • pyrophoric liquids
  • pyrophoric solids
  • self-heating substances and mixtures
  • substances and mixtures which, in contact with water, emit flammable gases
  • oxidizing liquids
  • oxidizing solids
  • organic peroxides
  • corrosive to metals

What are the classes within the Environmental hazard group?

Criteria for classifying chemicals have been developed for the following environmental hazard class:

  • hazardous to the aquatic environment (acute and chronic)
  • hazardous to the ozone layer

In addition, there are specific classification rules for chemical mixtures for each environmental hazard class.

What is the target date for implementation of GHS?

Consultations through the National WHMIS Office with stakeholder associations are essentially complete. An interim policy has been established to permit use of GHS-formatted safety data sheets in Canada. Additional interim policies may be developed. Regulatory proposals to update WHMIS are anticipated in 2011.

Will GHS affect other laws in Canada?

It is very likely. GHS is expected to be implemented by other regulatory agencies, including by Transport Canada for the Transport of Dangerous Goods, and by Health Canada for Consumer Chemical Products and Pest Control Products. Discussions are occurring but the consultations are not complete.

How will GHS change WHMIS?

Roles and Responsibilities

Overall, the current roles and responsibilities for suppliers, employers and workers likely will not change in WHMIS after GHS.

Suppliers, Importers and Producers duties will continue to include:

  • classifying hazardous products,
  • preparing labels and SDSs, and
  • providing these elements to customers.

Employers must continue to:

  • educate and train workers on the hazards and safe use of products,
  • ensure that hazardous materials are properly labelled,
  • prepare workplace labels and SDSs as necessary,
  • provide access for workers to up-to-date SDSs, and
  • ensure appropriate control measures are in place to protect the health and safety of workers.

Workers will still:

  • participate in WHMIS and chemical safety training programs,
  • take necessary steps to protect themselves and their coworkers, and
  • participate in identifying and controlling hazards.


How chemicals are classified will be affected. It is likely (but not confirmed) that WHMIS legislation will:

  • Adopt all of the major GHS health and physical hazard classes including aspiration hazard and specific target organ toxicity-single exposure. Some sub-categories in GHS may not be adopted. It is unlikely that the environmental hazard classes will be adopted under WHMIS (but this does not exclude that it may be adopted by another government department).
  • Continue to include some hazards that are currently not in the GHS system, but are present in the current WHMIS system – such as biohazardous materials.
  • Have more specific names for its hazard classes.
  • Combine two WHMIS classes (teratogenicity/embryotoxicity and reproductive toxicity) into one new GHS hazard class called reproductive toxicity

Supplier labels

Labels requirements will also change, and will probably have a few new requirements. Labels will use new pictograms, as well as a signal word – Warning or Danger.

Under the GHS system, once a chemical is classified, specific signal words, hazard statements and symbols/pictograms are required (prescribed) for each hazard class and category. These elements must appear on the label.

All of the required elements for labels are not yet determined. It is still not clear, for example, if the names of hazardous ingredients will be included on the label, or if the WHMIS hatched border will still be required.

Safety Data Sheets (SDSs)

SDSs will use a 16-section format. There will be standardized information requirements for each section. The 9-section WHMIS format for MSDSs will no longer be acceptable. Another important change to note is that the product classification and some of the label information will probably be required on the SDS. The SDS updating requirements (every 3 years) will likely be required.