Technical guidances

  1. Implementation EFSA OPEX model

  2. Guidances on derivation of soil and groundwater exposure

Implementation EFSA OPEX model

During the assessment of plant protection products, models are often used to estimate human exposure while using a product. People that can be exposed include the operators that apply the product, agricultural workers, bystanders and residents. Various exposure models are available, but until now the use of these models has not been harmonised within the EU. In the Netherlands, the law (Rgb, Bgb) specifies which exposure models must be used, as long this has not been harmonised at the EU level. In 2014 the EFSA Guidance on the assessment of exposure of operators, workers, residents and bystanders in risk assessment for plant protection products was published. This Guidance has been developed to support risk assessors and applicants when quantifying potential systemic exposure (non-dietary) as part of the risk assessment of plant protection products. The model can be used as a first tier calculation – actually an initial coarse approximation of exposure in the described exposure scenarios. For scenarios that are not described in the model, a case-by-case approach is required; this also applies to higher-tier assessments of scenarios in the model. An exposure calculator spreadsheet is also available as a tool; however EFSA emphasises that the Guidance itself takes precedence.

Effective date

Because the Guidance contributes to EU-harmonised procedures, the Board has decided to implement this Guidance for all substance and product applications that are submitted from 1 January 2016, with the exceptions listed under point 1.

  1. For active substances for which no acute AOEL (AAOEL) has been derived at EU level, also at national authorisation level there will be no AAOEL derived. Until a method has been described for deriving the Acute Acceptable Operator Exposure Level (AAOEL), this will not be included in the risk assessment. For operators and bystanders, this means that the risk of exposure to substances with the potential for acute effects is not calculated; the risk of long-term exposure to substances for bystanders is included in the assessment of risks for residents. This is in line with European agreements (SANTE-10832-2015 Rev. 1.7).

When preparing the Guidance, the Commission decided to leave it to the Member States to decide if they want to include the module for bystanders and residents. This is because the EFSA only includes a first-tier risk assessment for bystanders/residents; a harmonised methodology to refine the first tier, if required, is not yet available. However, the Ctgb has decided to implement the EFSA module for bystanders and residents as of 1 January 2016. This is because the Board assigns a high priority to the best possible risk assessment for these groups. As a second-tier, it may be feasible to use new substance or formulation data (e.g. DT50 or dermal absorption), or expert judgment. Each refinement step must always be scientifically substantiated and justified.

NL addendum human toxicology

Applications that are submitted to the Ctgb from 1 January 2016 under the new assessment framework must use the new dRR format; in that case, an NL addendum will no longer be required. The basic principle is harmonisation, which means that the results of the assessment of the zRMS will be accepted in principle. Where possible, the zRMS will use the EFSA model.
However, if the plant protection product consists of 2 or more active substances, or if a combination with other products is prescribed, combitox must be addressed in the core dossier as drawn up by the zRMS.
Moreover, in the core dossier all realistic operator scenarios with regard to tractor bound vs handheld, and upward vs downward spraying should be taken into account. This is indicated in the list  Field use scenario list TOX, see Evaluation Manual Chapter 4 Human Toxicology.
Applicants should also take into account the Dutch list of spray volumes, as other spray volumes could result in higher dermal absorption values and thus higher exposures

Evaluation Manual

The Evaluation Manual will be modified in the standard round. Among other things, this will include the description of the method and/or model that the Ctgb proposes for various scenarios, which cannot be assessed with the EFSA OPEX model. Examples include the NL greenhouse models for greenhouse applications and ConsExpo for spraying applications.

Guidances on derivation of soil and groundwater exposure

Two major guidance documents have been noted at the EU Standing Committee on Plants, Animals, Food and Feed recently. The guidances covering the areas of derivation of soil (DegT50 values) and groundwater exposure. Both have an implementation date of 1 May 2015 and can be found on the EU website under Technical guidance - Fate and behaviour.

  1. Guidance Document for evaluating laboratory and field dissipation studies to obtain DegT50 values of active substances of plant protection products and transformation products of these active substances in soil.
    This Guidance Document (SANCO/12117/2014) covers a number of areas, principally relating to methods for deriving the DegT50matrix from individual laboratory and field dissipation studies and additional guidance on selecting the appropriate input parameters for use in environmental exposure modelling.
  2. Assessing Potential for Movement of Active Substances and their Metabolites to Ground Water in the EU.
    This Guidance Document (SANCO/13144/2010) describes several higher tier options for groundwater assessments.


In addition, the Generic Guidance for Tier 1 FOCUS Ground Water Assessments (version 2.2, May 2014) has been updated to reflect the EFSA DegT50 guidance (2014) and also other EFSA PPR recommendations. Principal changes include the use of two FOCUS models for PECgw (Predicted Environmental Concentration in groundwater) simulations, use of geomean values for Kom, Koc and DegT50, recommendations relating to the use of pH dependent modelling, recommended default value of 0 for the Transpiration Stream Concentration Factor (TSCF) for all compounds and new FOCUS crop interception values for some crops.