Principles of classification

The criteria for the physical hazards can be found in Part 2 of the GHS. The GHS contains classification criteria for 17 physical hazard classes. GHS clearly depicts what endpoints should be used for each hazard class and what type of studies that should be referred to. 

However, not all physical hazard classes are relevant for pesticides (see table below). Generally, if a pesticide product fulfils the criteria of any of the physical hazards which are not marked as relevant in the table, it will not be authorized for use in the first place (e.g. a pesticide will never be explosive).

The classification procedures for physical hazards in the GHS originate generally from the UN Recommendations on the Transport of Dangerous Goods, in which methods and criteria have been well established and described.

In most cases, it is not possible to calculate classification of a pesticide formulation from the physical hazard classification of the active ingredient alone. This means that testing of the pesticide product itself is often necessary.

Hazard categories

Each hazard class is differentiated in hazard categories, with the lower number or code generally representing a higher, more serious, hazard. Only the hazard classes which are most relevant for pesticide products are shown here. For the other physical hazard classes, would they be applicable to a pesticide, please refer to Part 2 of the GHS.

Labelling elements

Annex A1 of the GHS contains classification and labelling tables where pictograms, signal words and hazard statements can be found for all hazard classes and hazard categories.

A summary table is provided below:

Data required for classification of physical hazards

Comprehensive data is often required for pesticides when applications are submitted to authorities for registration. Such data is therefore available in the registration dossiers and/or on-line in many countries and regions and may also be used for classification purposes. Such on-line data sources can be found in the Information Sources module in the Toolkit.

The following data generally need to be available to classify GHS physical hazards. If data have been generated with the pesticide product, these have strong preference. In some cases, physico-chemical data for the active ingredient, as well as relevant other components of the pesticide product, can also be assessed.

Detailed information about the data required for physical hazards classification can be in the “data requirement and test guidelines” module of the Toolkit, by clicking on the links in the table.

Detailed test guidelines can be found in the UN Manual of Tests and Criteria.

Assigning hazard categories

The GHS describes in detail how hazard categories should be assigned for each physical hazard class. A summary of these methods can be found by clicking on the entries below.

• Flammable gases
• Aerosols and chemicals under pressure
• Oxidizing gases
• Gases under pressure
• Flammable liquids
• Water reactive – emits flammable gases
• Oxidizing liquids
• Oxidizing solids
• Organic peroxides

More detail is provided in the GHS document and the UN Recommendations on the Transport of Dangerous Goods and its Manual of Tests and Criteria in which methods and criteria are well developed and described.  

Further guidelines on tests and evaluation of physical properties are available in the EU guidance document “Guidance document for the generation and evaluation of data on the physical, chemical and technical properties of plant protection products under regulation (EC) No. 1107/2009 and in “Guidance on the Application of the CLP Criteria”.

Procedures for classification

The Registration Authority can use different approaches to classify the product or verify a proposed classification. Which of these approaches can be applied, depends on the exact pesticide product to be classified and on the human resources available at the Registration Authority.

These different approaches are described in more detail under Assessment methods.