European scenarios for exposure of soil organisms to pesticides

Statement of the Scientific Panel on Plant Protection Products and their Residues (PPR Panel) on the design and conduct of groundwater monitoring studies supporting groundwater exposure assessments of pesticides

Groundwater monitoring is the highest tier in the leaching assessment of plant protection products in the EU. The European Commission requested EFSA for a review by the PPR Panel of the scientific paper of Gimsing et al. (2019) on the design and conduct of groundwater monitoring studies. The Panel concludes that this paper provides many recommendations; however, specific guidance on how to design, conduct and evaluate groundwater monitoring studies for regulatory purposes is missing. The Panel notes that there is no agreed specific protection goal (SPG) at EU level. Also, the SPG has not yet been operationalised in an agreed exposure assessment goal (ExAG). The ExAG describes which groundwater needs to be protected, where and when. Because the design and interpretation of monitoring studies depends on the ExAG, development of harmonised guidance is not yet possible. The development of an agreed ExAG must therefore be given priority. A central question in the design and interpretation of groundwater monitoring studies is that of groundwater vulnerability. Applicants must demonstrate that the selected monitoring sites represent realistic worst-case conditions as specified in the ExAG. Guidance and models are needed to support this step. A prerequisite for the regulatory use of monitoring data is the availability of complete data on the use history of the products containing the respective active substances. Applicants must further demonstrate that monitoring wells are hydrologically connected to the fields where the active substance has been applied. Modelling in combination with (pseudo)tracer experiments would be the preferred option. The Panel concludes that well-conducted monitoring studies provide more realistic exposure assessments and can therefore overrule results from lower tier studies. Groundwater monitoring studies involve a high workload for both regulators and applicants. Standardised procedures and monitoring networks could help to reduce this workload.

Statistically based soil-climate exposure scenarios for aquatic pesticide fate modeling and exposure assessment in the Pampa Region of Argentina

Although pesticides are used intensively in Argentina's Pampa region, the possibility of performing an environmental risk assessment (ERA) remains limited due to the absence of readily available databases to run pesticide fate models and the lack of standardized realistic worst-case scenarios. The aim of the present study was to further advance capacities for performing probabilistic ERAs in the Pampa region by dividing and parameterizing the region into functional soil-climate mapping units (SCU) and defining statistically based, worst-case soil-climate exposure scenarios. Results obtained demonstrate that the SCU selected for a specific modeling exercise should depend on the dissociation constant (K_d ) of the pesticide evaluated and whether short- or long-term pesticide fate modeling and risk assessment are needed. Four regionally representative SCUs were specifically identified for modeling the fate of pesticides with low, high, and intermediate values of K_d . Fate modeling of pesticides with an intermediate K_d requires the use of a different SCU for short- versus long-term pesticide modeling, whereas this distinction is not necessary for pesticides with both low and high K_d . The current definition of realistic, worst-case, soil-climate scenarios represents a crucial step toward better pesticide fate modeling and exposure assessment in Argentina's Pampa region. Integr Environ Assess Manag 2023;19:626-637. © 2022 SETAC.

Detecting the combined toxicity of 18 binary and 24 ternary pesticide combinations to carboxylesterase based on fluorescence probe technology

A rapid test method for the determination of pesticide toxicity was established by using carboxylesterase (CES) and fluorescence probe ACE-NH based on the principle of enzyme inhibition, and this method was applied to detect the combined toxicity of 18 binary and 24 ternary pesticide combinations commonly used for fruits and vegetables to CES. The results show that chlorpyrifos + carbendazim, carbofuran + carbendazim, imidacloprid + carbendazim, imidacloprid + dimethomorph, dimethoate + dimethomorph, prochloraz + carbendazim and imidacloprid + acetamiprid + carbendazim had synergistic effects under three concentration gradients, it indicated that most binary combinations containing carbendazim or imidacloprid had synergistic effects. Based on structure-activity relationship between pesticides and CES, pesticides with phosphate ester bonds had great toxicity to CES, or though they have no toxicity to CES alone, they showed a strong synergistic effect when mixed with other pesticides. Pesticides with amide or ester bond had medium toxicity and little synergistic effect. Pesticides with urea, carbamate or nitrite nitrogen group had little or no toxicity, while there was a strong synergistic effect after mixing with other pesticides. The test method and results in this study can provide scientific basis for risk assessment of cumulative exposure to mixed pesticide residues.

EFSA Guidance Document for predicting environmental concentrations of active substances of plant protection products and transformation products of these active substances in soil: This guidance published on 19 October 2017 replaces the earlier version published on 28 April 2015

This EFSA Guidance Document provides guidance for the exposure assessment of soil organisms to plant protection products (PPPs) and their transformation products in accordance with Regulation (EC) No. 1107/2009¹ of the European Parliament and the Council. This guidance was produced by EFSA in response to a question posed by the European Commission according to Article 31 of Regulation (EC) No. 178/2002² of the European Parliament and of the Council. Guidance is provided for all types of concentrations that are potentially needed for assessing ecotoxicological effects, i.e. the concentration in total soil and the concentration in pore water, both averaged over various depths and time windows. The current guidance considers both permanent crops and annual crops. The recommended exposure‐assessment procedure consists of four tiers. To facilitate efficient use of the tiered approach in regulatory practice, user‐friendly software tools have been developed. In higher tiers of the exposure assessment, crop interception and subsequent dissipation at the crop canopy may be included. The models that simulate these processes were harmonised. In addition, easy‐to‐use tables for the fraction of the dose intercepted by the canopy that is washed off have been developed, which should be used in combination with the simple analytical model. With respect to substance‐specific model inputs, this guidance generally follows earlier documents; however, new guidance is included for some specific substance parameters.

This publication is linked to the following EFSA Supporting Publications article: http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2017.EN-1288/full, http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2019.EN-1756/full, http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2019.EN-1761/full, http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2019.EN-1762/full, http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2019.EN-1763/full

Pesticide exposure assessment for surface waters in the EU. Part 2: Determination of statistically based run-off and drainage scenarios for Germany

BACKGROUND

In order to assess surface water exposure to active substances of plant protection products (PPPs) in the European Union (EU), the FOCUS (FOrum for the Co-ordination of pesticide fate models and their USe) surface water workgroup introduced four run-off and six drainage scenarios for Step 3 of the tiered FOCUSsw approach. These scenarios may not necessarily represent realistic worst-case situations for the different Member States of the EU. Hence, the suitability of the scenarios for risk assessment in the national authorisation procedures is not known.

RESULTS

Using Germany as an example, the paper illustrates how national soil-climate scenarios can be developed to model entries of active substances into surface waters from run-off and erosion (using the model PRZM) and from drainage (using the model MACRO). In the authorisation procedure for PPPs on Member State level, such soil-climate scenarios can be used to determine exposure endpoints with a defined overall percentile.

CONCLUSION

The approach allows the development of national specific soil-climate scenarios and to calculate percentile-based exposure endpoints. The scenarios have been integrated into a software tool analogous to FOCUS-SWASH which can be used in the future to assess surface water exposure in authorisation procedures of PPPs in Germany. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Pesticide exposure assessment for surface waters in the EU. Part 1: Some comments on the current procedure

In 2001, the European Commission introduced a risk assessment project known as FOCUS (FOrum for the Coordination of pesticide fate models and their USe) for the surface water risk assessment of active substances in the European Union. Even for the national authorisation of plant protection products (PPPs), the vast majority of EU member states still refer to the four runoff and six drainage scenarios selected by the FOCUS Surface Water Workgroup. However, our study, as well as the European Food Safety Authority (EFSA), has stated the need for various improvements. Current developments in pesticide exposure assessment mainly relate to two processes. Firstly, predicted environmental concentrations (PECs) of pesticides are calculated by introducing model input variables such as weather conditions, soil properties and substance fate parameters that have a probabilistic nature. Secondly, spatially distributed PECs for soil-climate scenarios are derived on the basis of an analysis of geodata. Such approaches facilitate the calculation of a spatiotemporal cumulative distribution function (CDF) of PECs for a given area of interest and are subsequently used to determine an exposure concentration endpoint as a given percentile of the CDF. For national PPP authorisation, we propose that, in the future, exposure endpoints should be determined from the overall known statistical PEC population for an area of interest, and derived for soil and climate conditions specific to the particular member state. © 2016 Society of Chemical Industry.

Surface water risk assessment of pesticides in Ethiopia

Scenarios for future use in the pesticide registration procedure in Ethiopia were designed for 3 separate Ethiopian locations, which are aimed to be protective for the whole of Ethiopia. The scenarios estimate concentrations in surface water resulting from agricultural use of pesticides for a small stream and for two types of small ponds. Seven selected pesticides were selected since they were estimated to bear the highest risk to humans on the basis of volume of use, application rate and acute and chronic human toxicity, assuming exposure as a result of the consumption of surface water. Potential ecotoxicological risks were not considered as a selection criterion at this stage. Estimates of exposure concentrations in surface water were established using modelling software also applied in the EU registration procedure (PRZM and TOXSWA). Input variables included physico-chemical properties, and data such as crop calendars, irrigation schedules, meteorological information and detailed application data which were specifically tailored to the Ethiopian situation. The results indicate that for all the pesticides investigated the acute human risk resulting from the consumption of surface water is low to negligible, whereas agricultural use of chlorothalonil, deltamethrin, endosulfan and malathion in some crops may result in medium to high risk to aquatic species. The predicted environmental concentration estimates are based on procedures similar to procedures used at the EU level and in the USA. Addition of aquatic macrophytes as an ecotoxicological endpoint may constitute a welcome future addition to the risk assessment procedure. Implementation of the methods used for risk characterization constitutes a good step forward in the pesticide registration procedure in Ethiopia.