Principles of classification

Human health hazard identification is the identification of the type and nature of adverse effects that a pesticide may cause in an organism. A hazard assessment is based on the intrinsic toxicity of the product and does not take into account the degree of exposure of a person to the pesticide.

The criteria for the health hazards can be found in Part 3 of the GHS. The GHS contains classification criteria for ten health hazard classes which are further described below. GHS clearly depicts what endpoints should be used for each hazard class and what type of studies that should be referred to. In case data on the pesticide formulation itself is not sufficient or is not available, it may be possible to apply the so-called bridging principles which are described under each chapter.

In the GHS, either “substances” or “mixtures” are classified. In the case of pesticides, a “substance” would refer to the active substance or active ingredient of the pesticide; a “mixture” refers to the pesticide formulation or pesticide product. A pesticide formulation will often consist of various substances (both active ingredient(s) and co-formulant(s)) that each may require classification. The classification of a pesticide formulation will generally be based on the classification of the individual components as well as the concentration or potency of each component in the mixture.

Not all pesticide formulations require a GHS classification. If concentrations of the (active) ingredient(s) are very low, the pesticide formulation may not need to be classified and its hazard will be considered to be low. In the GHS the term “concentration limit/cut-off value” is generally applied to indicate concentration thresholds used to decide whether classification is needed or not. For the purposes of the GHS, the terms “cut-off value” and “concentration limit” are equivalent and are meant to be used interchangeably. Competent authorities may choose whether to use either term to define thresholds that trigger classification. The minimum concentrations for a substance to be taken into account for human health classification for each hazard class is found in Part 3 of the GHS under the heading “Classification criteria for mixtures”.

For the classification of a pesticide formulation (i.e. a “mixture” in the GHS) the following approaches apply for the different hazard classes; this is further explained in the sections about assigning hazard categories.

Hazard categories

Each hazard class is differentiated in hazard categories, with the lower number representing a higher, more serious, hazard. For instance, a carcinogen Category 1A poses a more serious cancer hazard than a carcinogen Category 2).

Hazard categories are based on the severity of reaction or strength of available evidence. For instance, if a hazard is shown based on human evidence this will lead to a higher hazard category (i.e. lower category number) than when it is based on animal test data alone.

For reproductive toxicity, a hazard for lactation is a separate category, not included in the numbered hazard categories.

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 health classification

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 mandate for development of the GHS does not include establishment of uniform test methods or promotion of further testing to address adverse health outcomes. Tests that determine hazardous properties, which are conducted according to internationally recognized scientific principles, can be used for human health hazard classification. The GHS criteria for determining health hazards are test method neutral, allowing different approaches as long as they are scientifically sound and validated according to international procedures.

In addition to animal data and valid in vitro testing, human experience, epidemiological data and clinical testing provide important information that should be considered in application of the GHS.

The following data generally need to be available to classify GHS human health hazards. If data have been generated with the pesticide product, these have preference. Alternatively, toxicity data for the active ingredient, as well as relevant other components of the pesticide product, should be assessed.

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

Assigning hazard categories

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

• Acute toxicity
• Skin corrosion/irritation
• Serious eye damage/eye irritation
• Respiratory or skin sensitization
• Germ cell mutagenicity
• Carcinogenicity
• Reproductive toxicity
• STOT – single exposure
• STOT – repeated exposure
• Aspiration toxicity

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.