Principle

This assessment evaluates the risk of a formulated product to pesticide operators using exposure models. Based on an appropriate exposure scenario, operator exposure to a pesticide product is being estimated by a model and the outcome is compared with a toxicological reference value.

An exposure scenario is a description of the situation where the operator is exposed to the pesticide. It typically includes: the type of application equipment used, pesticide formulation, application rate, crop type, spray direction, work rate, level of personal protection, etc.

Regulatory operator exposure models have been available for some time for European and North American pesticide application situations. More recently, a global model has been published specifically for handheld pesticide application equipment. 

Tools

Several regulatory operator risk assessment tools are currently available.

ICPPE Risk Assessment and Mitigation Tool

The ICPPE Risk Assessment and Mitigation Tool became available in 2025. It is the result of an international multi-stakeholder initiative coordinated by the International Center for Personal Protective Equipment for Pesticide Operators and Re-entry Workers (ICPPE), at the University of Maryland Eastern Shore in the USA.

The ICPPE Tool allows the estimation of pesticide operator exposure following outdoor (field) and indoor (greenhouse) pesticide applications with backpack sprayers and other handheld sprayers. It is based on currently the largest global database of exposure studies using handheld application equipment.

The ICPPE Tool also allows the estimation of operator exposure when using tractor-mounted equipment, by using the models of the EFSA OPEX Calculator.

The ICPPE Risk Assessment and Mitigation Tool is MS Windows-based and can be downloaded from the ICPPE web site. Registration, free of charge, is needed before the Tool can be downloaded. A guidance document on pesticide operator risk assessment and use of the ICPPE Tool is available on the same web page, as are links to scientific articles describing the underlying data.

The ICPPE Tool has an “on-demand” user manual, integrated in its different screens; it can be accessed by clicking the questions marks above each field. 

EFSA OPEX (2025) Calculator

The European Food Safety Authority (EFSA) OPEX (2025) Calculator was originally published in 2022 and revised in 2025. It replaces the earlier EFSA spreadsheet. The EFSA OPEX Calculator is based on the Agricultural Operator Exposure Model (AOEM) and the Greenhouse AOEM.

The EFSA OPEX Calculator allows the estimation of pesticide operator exposure following outdoor (field) and indoor (greenhouse) pesticide applications with tractor-mounted spray equipment as well as handheld sprayers; application of granules is also included.

Most cropping scenarios are specific for Europe, although many may also be applicable to other regions. The pesticide regulator needs to verify whether this is likely to be case. The database underlying the handheld applications is relatively small.

The EFSA OPEX Calculator is available on-line, on the EFSA Statistical Models web page. An account is required to access the calculator; signing up is free of charge. Direction for use are provided under the “Info” tab of the calculator.

Further details about the operator risk assessment approach applied in the European Union are described in an EFSA guidance document (2022).

US EPA Occupational Pesticide Handler Exposure Calculator

The of the United States Environmental Protection Agency (US EPA) uses the Occupational Pesticide Handler Exposure Calculator to estimate the exposure of a “handler”, those that are involved in the pesticide application process (mixer, loader, applicator, flagger).

The Calculator is a Microsoft Excel-based tool, which can be downloaded from the US EPA web site. It is based on the Occupational Pesticide Handler Unit Exposure Surrogate Reference Table, available from the same web page.

A large number of exposure scenarios are included in the EPA Calculator, for handheld, vehicle-mounted and aerial applications, with different pesticide formulations and different activities/application sites.

A user guide for the Calculator is provided in the first tab of the spreadsheet.

The above-mentioned models are different with regard to the exposure scenarios which they cover, the underlying exposure studies which are at the basis of the models, the degree of protection provided by personal protective equipment, and some of the default assumptions on absorption of the pesticide into the body.

A comparison of the main exposure scenarios and the assumptions of the three models listed on this page is provided here.

Data required

The following input data are required to use the different operator risk assessment tools. Most of these should be provided by the applicant as part of the registration dossier. Some information, especially referring to local conditions of use of the product, will be known by the pesticide registration authority.

Procedures

1. Describe the operator exposure scenario(s) applicable to the pesticide to be evaluated

2. In the exposure models, choose the exposure scenario(s) which most closely approaches the situation that you wish to evaluate.

3. Obtain the input data to run the model from the registration application dossier or, if absent, from reputable alternative sources.

4. Run the model(s).

5. If provided by the model, note the estimated total systemic exposure (mg a.i./kg bw/day).

6. Note the AOEL.

7. Calculate or note the exposure as % of the AOEL.

This Assessment Summary Table for Operator risk models can be used to summarize the data.

Interpretation of the outcome

The risk of the application is considered acceptable for the operator when the predicted exposure level is lower than the AOEL. Most of the models listed above show the total systemic exposure to the pesticide as a percentage of the AOEL, and exposure < 100% AOEL is considered acceptable.

If the risk is unacceptable, one can assess whether any risk mitigation measures (e.g. using personal protective equipment or engineering control) can be applied to reach an acceptable operator risk. If risk mitigation measures are required, one should also evaluate whether they are feasible and realistic under the local conditions of use of the pesticide.

Alternatively, if the risk is unacceptable, higher tier risk assessments may be done, such as using measured pesticide absorption rates rather than the default ones provided in the model; using exposure levels that have been measured under local pesticide use conditions rather than the model estimates.