The Agricultural Operator Exposure Model (AOEM) and Southern European Greenhouse Model
The 2014 EFSA guidance saw the introduction of the Agricultural Operator Exposure Model (AOEM), which had been developed by BfR up to 2013. This was the first truly harmonised operator exposure model for Europe and whilst the working group comprised both representatives from leading EU regulatory authorities and CropLife Europe (CLE), the data underpinning the model were all generated by the crop protection Industry. The studies included were not conducted to a standard protocol for the purpose of developing a model but mostly to support the registration of active substances and products of the CLE member companies, yet they were selected according to a set of clearly defined criteria. This model allowed predictions of exposure for outdoor application by vehicle mounted and hand-held equipment but in the 2022 update of the guidance, the associated calculator was extended to include protected cropping scenarios, primarily using data generated in 14 studies by CLE to support the development of the “Southern European Greenhouse Model” (2010), further developed by BfR 2015, 2020.
An additional benefit gained from having a comprehensive database of operator exposures is that it quantifies the degree of protection afforded by work clothing and personal protective equipment (PPE) through actual exposure measurements in the field. This evidence was used to support CLE arguments that PPE does not underperform and to explain that the default assigned protection factors in the EFSA guidance are very rarely used (Morgan, et al., 2020).
CropLife Europe Contributions:
EFSA 2014: Guidance on the assessment of exposure of operators, workers, residents and bystanders in risk assessment for plant protection products. (https://www.efsa.europa.eu/en/efsajournal/pub/3874)
EFSA 2022: Guidance on the assessment of exposure of operators, workers, residents and bystanders in risk assessment for plant protection products. (https://www.efsa.europa.eu/en/efsajournal/pub/7032)
BfR (Bundesinstitut fuer Risikobewertung, German Federal Institute for Risk Assess), 2015. Joint development of a new Greenhouse Agricultural Operator Exposure Model for handheld application. BfR, Berlin. 117 pp.
BfR (Bundesinstitut fuer Risikobewertung, German Federal Institute for Risk Assess), 2020. Update of the Greenhouse Agricultural Operator Exposure Model – Amendment to Project Report 01/2016. BfR, Berlin. 133 pp. Available online: https://www.bfr.bund.de/cm/350/revision-of-the-greenhouse-agricultural-operator-exposure-model.pdf
Mielke, Hans & Großkopf, Claudia & Westphal, Dieter & Erdtmann-Vourliotis, M. & Hamey, Paul & Bouneb, Francoise & Rautmann, Dirk & Stauber, Franz & Wicke, Heinrich & Maasfeld, Wolfgang & Salazar, Domingo & Chester, Graham & Martin, Sabine. (2013). A new model for the prediction of agricultural operator exposure during professional application of plant protection products in outdoor crops. Journal für Verbraucherschutz und Lebensmittelsicherheit. 8. 143-153.10.1007/s00003-013-0836-x Available online: https://www.bfr.bund.de/cm/350/joint-development-of-a-new-agricultural-operator-exposure-model.pdf
Closed Transfer Systems (CTS)
Operators handling PPPs pour the product from the container to the tank of the sprayer and whilst developments in equipment design, e.g., induction hoppers offer reductions in mixing and loading exposure, there is still room for improvement. Closed transfer systems (CTS) exist but have never been included in PPP assessments as a risk mitigation measure. CLE initiated a study of 3 types of CTS (the inverted extraction systems, easyFlow M and easyconnect, plus the probe extraction system, GoatThroat®) to derive a generic exposure reduction factor that could cover all systems which comply with ISO 21191:21 standard which outlines a performance specification for such equipment.
Dermal exposure was measured for 12 operators in 4 European countries whilst they handled experimental formulations designed to reflect the range of active substance loading and viscosity of the commercial formulations used in the studies which support the AOEM. All 3 CTS significantly reduced dermal exposure against the AOEM. Inverted types led to lower exposures than GoatThroat®, but the latter still performed well although it was designed for smaller spraying operations. Sasturain et al propose introducing generic exposure reduction factors of 90% and 70% into the AOEM for inverted CTS and probe extraction CTS types respectively. This project could lead to increased uptake of CTS amongst farmers as there is now firm evidence of the benefits. CLE undertook engagement activities with multiple stakeholders including the EC. It is hoped that this increased transparency will see acceptance of CTS for risk mitigation and will pave the way for future interactions between industry and regulators.