Pesticide Registration Toolkit

Worker exposure models and local risk assessment

Relevant documents
Worker exposure models summary table 
Equations and assumptions underlying the EFSA Calculator worker exposure model 


This assessment evaluates the risk of the formulated product for agricultural workers using exposure models. Using an appropriate exposure scenario, exposure of workers to a pesticide is being estimated by a model and the outcome is compared with the acceptable operator exposure level (AOEL).
An exposure scenario is a description of the situation where the worker is exposed to the pesticide. It typically includes: the crop type and density, pesticide half-life, transfer coefficient, application rate, work rate, level of personal protection, etc.
Worker exposure models have been developed mainly for European and North American pesticide application situations, but not (yet) for developing countries. However, by choosing the appropriate exposure scenarios, existing models can be used to obtain an initial indication of occupational exposure to a pesticide and assess the risk to the worker.


Several worker exposure models are available, although they tend to apply similar calculations. The following models describe a range of exposure scenarios and are based relatively recent data.
1. The European Food Safety Authority (EFSA) Calculator was published in 2014 and contains a worker exposure model.
The EFSA Calculator replaces various older European exposure models such as EUROPOEM and the German BBA model.
Both the EFSA Calculator and further details about the worker risk assessment approach applied in the European Union can be downloaded here (see section 'Supporting Information' for download of actual model).
2. The US-EPA ExpoSAC model.
[TODO Note: section  to be developed]
Data required
The following data are generally used for a worker risk assessment using an exposure model.
  • Acceptable Operator Exposure Level (AOEL) (In the EFSA Calculator, the AOEL is referred to as the “Reference value non acutely toxic active substance” (RVNAS))
  • Crop type
  • Type of application and application equipment.
  • Maximum application rate (kg of a.i. per ha).
  • (If available) dermal absorption factor.
  • (If available) pesticide-specific dislodgeable foliar residue
  • Type of personal protective equipment available/required.


  1. Describe the worker exposure scenario(s) applicable to the pesticide to be evaluated
  2. In the exposure models, choose the crop and application parameters which most closely approach 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 Worker exposure model summary table  can be used to summarize the data.

Interpretation of the outcome

The worker risk is considered acceptable when the predicted exposure level is lower than the AOEL. The model listed above shows 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; applying a longer re-entry period) can be applied to reach an acceptable worker 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 or dislodgeable foliar residues, rather than the default ones provided in the model.