Pesticide Registration Toolkit

Decision making – Elements


Efficacy assessment in the registration of a pesticide should be carried out, where applicable, to ensure that pesticides approved will be effective for its intended use.

Effectiveness of the pesticide may be either “control” or “reduction” of the pest. Where other pest management methods are applied simultaneously with the pesticide, such as in IPM, reduction or suppression of the development of a target pest/disease/weed may be acceptable effectiveness. In such cases ”control” of the pest should not be claimed by the applicant. Alternatively, whenever “control” is claimed, the applicant should show that the treatment with the pesticide product keeps or kills the target pest/disease/weed below the damage threshold level.

The final outcome of the efficacy assessment is a definition of the minimum effective dose, the minimum frequency of application, and the recommended timing of the treatment(s), that result in the required effectiveness. This information is summarized in the good agricultural practice (GAP) table. The GAP recommendations should result in acceptable effectiveness of the product, but also minimize phytotoxicity or adverse effects on rotational and adjacent crops.

The GAP table is the basis for the directions for use stated on the label of the pesticide. It is also the starting point for the human health and environmental risk assessments.

Acceptable efficacy is a pre-supposition for registration of the pesticide in most countries: a pesticide that does not result in an effective level of control or reduction of the pest population will not be a candidate for registration, even if it does not pose risks to human health or the environment.

If the minimum effective dose and application frequency for a given crop/pest combination has been established as GAP, there will be limited or no possibility to reduce risks through modification of the GAP. However, in many countries efficacy testing is done only to confirm the dose rate recommended by the applicant. In such cases there may be an opportunity to reduce unacceptable risks by reducing the dose rate or application frequency, or by increasing the spray interval. 

Data requirements for efficacy studies are can be found here while the possible assessment options for the determination of biological efficacy are described here.

Human health and environmental risks

Risk assessments should be done for those protection goals that are set by (national) legislation. These cover both human health risks and environmental risks.

Risk assessment is generally conducted applying a tiered approach, with the lower tier being the most conservative (worst-case) evaluation of the exposure to and toxicity of the pesticide, i.e. situations that are more vulnerable than the “average” situation.

If the risk of the pesticide in the lower tier is low, there is no impediment to registration. If a risk is identified, the assessment moves to a higher tier, which represents a more realistic evaluation of the exposure to and toxicity of the pesticide, generally using more comprehensive and realistic data.

In any tier of the risk assessment, the effect of risk mitigation measures can be evaluated, that may reduce the risk of the pesticide to acceptable levels. Risk mitigation measure should in principle be effective, practicable, cost-effective, have an effect that can be quantified and have the possibility of enforcement.

If the risk is low when implementing risk mitigation, there would be no impediment to registration of the pesticide. However, registration should then only be granted under the condition that risk mitigation measures can realistically be implemented.

If, on the other hand, after the higher tier refinement of the assessment and possibly including risk mitigation measures, the risk is still considered to be too high, various options are open with respect to risk management of that pesticide, such as:

  • Deny registration of the high risk use(s) of the pesticide; but allow uses(s) with acceptable risks;
  • Deny registration of all uses of the pesticide (e.g. if the risks of using the product are high, and the probability of it being used on other crops or in other use situations is high);
  • Authorize the pesticide, with or without risk mitigation measures, but accept a certain level of risk (e.g. for pesticides which have a great agronomic importance and for which no alternative products or pest management options are available). This is a political decision and goes beyond the scientific assessment of risks.

Human health and environmental risk assessment methods, for different protection goals, are described in more detail in the Assessment Methods Tool (select the relevant category and sub-category to view the protection goal to be assessed). 



In principle, the registration of the pesticide should strengthen the sustainability of agricultural systems, i.e. the long-term productivity and diversity of agricultural production in the country. At least, the pesticide to be registered should not compromise agronomic sustainability.

Pesticides may compromise agricultural sustainability in various ways, including:

  • development of pest resistance, resulting in a reduction of pesticide efficacy and an increase in pesticide use;
  • adverse effects on pollinators, leading to a decrease in production quantity and/or quality;
  • adverse effects on natural enemies, leading to development of secondary pests or resurgence of existing pests;
  • adverse effects on succeeding (rotational) crop, or on adjacent crops;
  • adverse effects on soil organisms, which may affect nutrient cycling and soil fertility.

Many potential adverse effects on sustainability can be managed through risk mitigation measures. In exceptional cases, registration of the pesticide may be denied; e.g. when widespread resistance has already developed in the country against pesticides with the same mode of action as the one submitted for registration; or if case studies from other countries, for the same pesticide and use, clearly indicate widespread adverse effects on pollination or secondary pests appearing after the use of the pesticide.

On the other hand, if a pesticide contributes to or strengthens agricultural sustainability, the decision to register may be favoured. This may be the case, for instance, if the pesticide can be integrated readily into biological control programmes or IPM, or when the pesticide represents a new mode of action and can become part of a strategy to manage existing resistance problems.




The availability of alternatives to a newly to be registered pesticide may need to be assessed as part of the decision making process. This is in particular the case for pesticides posing a high risk to human health or the environment, or posing a high risk of compromising agricultural sustainability. If effective alternatives to such a pesticide are available in the country or can be operationalized, the registration authority may decide more readily not to register the pesticide.

Alternatives can be other registered chemical or biological pesticides, or they may be other pest control measures (e.g. biological control, agronomic interventions).

When a newly to be registered pesticide is compared with another chemical or biological pesticide, the following principles apply to decide whether sufficient pesticides are already available that are equally or more effective but less hazardous:

  • The already available pesticide(s) should be registered for the same or similar use(s).
  • The already available pesticide(s) should be equally or more effective against the target pest(s).
  • The already available pesticide(s) should pose less risk or require less risk mitigation.
  • A minimum number of pesticides with different modes of action, that can be used against the same pest, should be registered, to ensure that pesticide resistance can be properly managed, if applicable.

When a newly to be registered pesticide is compared with an alternative pest control measure, such as biological control or agronomic measures, the following principles apply to decide whether sufficient alternatives are available that are equally or more effective but less hazardous:

  • The already available alternative pest management method(s) should have been tested and/or successfully used for the same or similar use(s) in the country.
  • The already available alternative pest management method(s) should be equally or more effective against the target pest(s), alone or as part of IPM.
  • The already available alternative pest management method(s) should pose less risk or require less risk mitigation.
  • The already available alternative pest management method(s) should be practicable for farmers under local conditions of use.

Alternatives assessments are not easy to conduct, because few if any formal assessment procedures have been elaborated so far, even in registration systems with more resources. Therefore, alternatives assessments will be conducted primarily for pesticides posing a high risk to human health or the environment

Costs and benefits

As part of the decision making process, a registration authority may evaluate whether the benefits of registering the pesticide outweigh the risks of use under local socio-economic conditions.

In most cases, proof of efficacy establishes the nature of the expected benefits. A more in-depth cost-benefit evaluation is generally difficult to conduct. Expected benefits of the use of the pesticide will depend on crop yield, its quality and sales value, the latter which in turn depends on the volume of supply of the commodity in the country. A complicating factor is that effects of the pesticide on yield are often only available in comparison with no pest management practices at all (i.e. the untreated control plots in the efficacy trials), but not in comparison with normal farmer pest management practices; a situation which may inflate the beneficial effect of the pesticide.

Costs estimates will include direct and indirect costs to the farmer of using of the pesticide, but also externalities outside the farm, such as environmental effects or adverse effects on other economic activities such as fisheries or honey production.

Due to its complexity, an in-depth cost-benefit evaluation is not often conducted as a standard practice for registration.

In some cases, however, a cost-benefit evaluation of introducing a new pesticide into the country will be justified. For instance, if a pesticide poses a high risk but is considered necessary to manage an (emergency) pest for which no alternatives are available.

Alternatively, cost-benefit analysis may be warranted in those cases where relatively expensive risk mitigation measures are required and possible, e.g. if the pesticide is intended for the protection of high-value crops, or for migratory pest control. Also, cost-benefit evaluations may be called for when it is established that the pesticide is clearly needed by smallholder farmers, who often have very limited purchase power, but are not in a position to assess benefits of buying the pesticide in a reliable manner.