Availability of pesticide-treated seeds on the soil surface in different crops and countries: A comprehensive data set reflecting modern agronomic practice.

For plant protection products applied as seed treatments, the risk to birds and mammals possibly feeding on such treated seeds needs to be addressed in the EU, in order to register these products for commercial use. For this purpose, the European Food Safety Food Authority (EFSA) has provided guidance on how to execute such a risk assessment. The risk assessment follows a tiered approach. In the Tier 1 risk assessment of the EFSA guidance (2023), it is assumed that birds or mammals have ad libitum access to treated seeds and exclusively feed on treated seeds. Due to this conservative assumption, the Tier I risk assessment typically indicates an unacceptable risk to birds and mammals and higher-tier refinements are required. One option for refinement is to use data on the availability of treated seeds on the soil surface directly after drilling. Published data on seed counts are, however, limited to a few countries and crops, and often these data are not contemporary, that is, do not reflect advances in sowing technology and current agronomic practice. To address this data gap, we provide recently generated data from industry field trials (the studies were conducted from 2000 to 2022, >70% between 2019 and 2022), covering 270 fields from seven countries (Austria, France, Germany, Hungary, Poland, Spain, UK) for spring and winter cereals, winter oilseed rape, and sunflower. This comprehensive data set realistically reflects modern agronomic practice and is thus suitable for consideration in a regulatory context for refining the risk assessment for birds and mammals. Integr Environ Assess Manag 2024;00:1-8. © 2024 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Mechanistic modelling of amphibian body burdens after dermal uptake of pesticides from soil.

Amphibians are currently considered to be covered by pesticide Environmental Risk Assessment schemes by surrogacy assumptions of exposure and susceptibility based on typical laboratory test species such as fish, mammals, and birds. While multiple reviews have shown for this approach to be adequate in the case of aquatic stages, the same cannot be definitively stated for terrestrial stages. Concerns have risen that exposure of amphibians is likely to be highly influenced by dermal absorption, primarily due to the high permeability of their skin and the lack of a protective layer, such as fur or feathers. It is thus hypothesized that dermal uptake could be a significant route of exposure. Consequently, it is necessary to determine the relative importance of different exposure routes that might affect the integrated toxicity outcome for terrestrial amphibian life-stages. Here, a one-compartment Toxicokinetic model was derived and tested using a publicly available dataset containing relevant exposure and uptake information for juvenile anurans exposed to 13 different pesticides. Modelled body burdens were then compared to measured burdens for a total of 815 individuals. Overall, a good concordance between modelled and measured values was observed, with the predicted and measured body burdens differing by a factor of 2 on average (overall R2 of 0.80 and correlation coefficient of 0.89), suggesting good predictivity of the model. Accordingly, the model predicts realistic body burdens for a variety of frog and toad species, and overall, for anurans. As the model includes rehydration (implicit in the evaluated studies) but currently does not account for metabolism, it can be seen as a worst-case assessment. We suggest toxicokinetic models, such as the one here presented, could be used to characterize dermal exposure in amphibians, screen for pesticides of concern, and prioritize risk assessment efforts, whilst reducing the need for de novo vertebrate testing.

Decline of pesticide residue on treated crop seeds: An analysis of comprehensive industry data and implications of the current risk assessment scheme for plant protection products.

For plant protection products applied as seed treatments, the risk to birds and mammals possibly feeding on treated seeds must be addressed in the EU to register products for commercial use. One assumption of the Tier 1 long-term risk assessment of the European Food Safety Authority (EFSA) is that residues of pesticides on treated seeds do not decline over time after seeding. Consequently, a time-weighted average factor (fTWA ) of 1 (i.e., no dissipation) is used to calculate residue concentrations on seeds. In contrast, for spray applications, a default dissipation half-life (DT50 ) of 10 days is considered corresponding to an fTWA of 0.53. The aim of this study was to establish a default fTWA for treated seeds based on 29 industry-conducted seed dissipation studies, providing 240 datasets covering different active substances, crops, and regions. For fTWA calculation, two approaches were used: (i) kinetic fitting and (ii) using measured data without kinetic fitting. From kinetic fitting, 145 reliable DT50 values were obtained. Because there were no significant differences in DT50 values between crops and between the central and southern EU, the DT50 data from all studies were pooled. The geometric mean DT50 was 3.8 days and the 90th percentile was 13.0 days, corresponding to 21-day fTWA values of 0.27 and 0.59, respectively. Twenty-one-day fTWA values could be calculated directly from measured residues for 204 datasets. The resulting 21-day fTWA values were comparable with those from kinetic fitting (geometric mean: 0.29, 90th percentile: 0.59). The results demonstrate that residue decline on seeds is comparable with foliar dissipation after spray applications. Therefore, the risk assessment scheme by EFSA should implement a default fTWA < 1.0 in the Tier 1 risk assessment for treated seeds (e.g., either 0.53 as for foliage or 0.59, the 90th percentile fTWA in seeds reported in this study). Integr Environ Assess Manag 2024;20:239-247. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Predicted Dermal and Dietary Exposure of Bats to Pesticides.

Wild birds and mammals that feed in agricultural habitats are potentially exposed to pesticides through various routes. The European Food Safety Authority (EFSA) recently published a statement which concluded that the current EFSA risk assessment scheme for birds and mammals does not adequately cover bats (Chiroptera). In the present study, we take a more detailed look at the EFSA statement and assumptions made regarding direct (dermal) and indirect (dietary) exposure of bats to pesticides in terms of their realism and the potential implications for risk assessment outcomes. Regarding dietary exposure, errors in the residue per unit dose (RUD) values for flying insects (bat food), proposed in the EFSA bat statement, were identified and corrected. Lower RUD values based on a much broader data base are proposed. Using these more realistic RUD values, together with current assumptions regarding toxicity and exposure, the acute and long-term risk to bats appears to be within the range of those calculated for birds and ground-dwelling mammals under the current risk assessment scheme. Depending on the assumptions made, some uncertainties may remain and should be investigated further. According to the EFSA bat statement, dermal exposure of bats is the most significant route of exposure, resulting in the highest predicted daily doses. We demonstrated that the dermal exposure models in the EFSA bat statement predict much higher residues for bats than those measured for other flying organisms that have larger surface area to volume ratios, and thus would be expected to have the reverse relationship. We also illustrated that the amounts of spray liquid required to achieve the predicted dermal exposures of bats are implausibly high, with bats carrying an amount of spray liquid that exceeds their body weight many fold. It is recommended that a bat risk assessment framework should be based on realistic, sound science, allowing resources to be focused on those scenarios that are not already covered by the existing bird and mammal framework. Therefore, a quantitative risk assessment scheme should not be implemented until the many scientific uncertainties within the EFSA bat statement are addressed. Environ Toxicol Chem 2022;41:2595-2602. © 2022 Cambridge Environmental Assessments. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Residue Levels of Pesticides on Fruits for Use in Wildlife Risk Assessments.

The guidance document on risk assessment for birds and mammals (GD) provides generic residue values of pesticides on potential diet items for use in wildlife risk assessments. For most diet items, these values are based on a large number of residue studies. However, the default residues per unit dose (RUD; standardized for application of 1 kg substance per hectare) values for fruits were taken from a few literature trials of unclear relevance for regulatory purposes. These trials were conducted according to neither current European Union (EU) agricultural practice nor to recommendations given in the GD about how to conduct wildlife-relevant residue studies. Therefore, field study data on fruit residue levels from applications of pesticides in fruiting crops were compiled and evaluated. Corresponding studies had been conducted during the last 26 y in the EU. In the final data set, 291 studies provided 1002 residue values in different fruits, including grapes, berries (currants, raspberries, gooseberries), fruits from orchards (apple, peach, pear, lemon, mandarin, orange, apricot, cherry, plum), gourds (pumpkins, cucumbers, squash, melons), and strawberries. This data set provides a basis for revising registration-relevant RUD values for fruits as potential diet items for birds and mammals in environmental wildlife risk assessments. The objective of this study was to estimate the resulting residue levels in different fruits determined under field conditions following the application of pesticides across their growing areas within the EU in diverse climatic areas that can be used directly in wildlife risk assessments. The large data set of usually about more than 100 residue values per "fruit group," all evaluated at EU member state level, revealed significantly lower RUDs compared to the current default RUDs presented in the GD. These new RUD values for fruits should be considered for use as default values in future bird and mammal risk assessments and in respective guidance documents. Integr Environ Assess Manag 2021;17:552-561. © 2020 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology Chemistry (SETAC).

Historical control data for the interpretation of ecotoxicity data: are we missing a trick?

Wildlife can be exposed to chemicals in the environment from various anthropogenic sources. Ecotoxicity studies, undertaken to address the risks from potential exposure to chemicals, vary in their design e.g. duration of exposure, effect types and endpoints measured. Ecotoxicity studies measure biological responses to test item exposure. Responses can be highly variable, with limited opportunity for control of extrinsic sources of variability. It is critical to distinguish between treatment-related effects and background 'normal variability' when interpreting results. Historical control data (HCD) can be a valuable tool in contextualising results from single studies against previous studies performed under similar conditions. This paper discusses the case for better use of HCD in ecotoxicology assessments, illustrating with case studies the value and difficulties of using HCD in interpretation of results of standard and higher-tier study designs. HCD are routinely used in mammalian toxicology for human health assessments, but not directly in ecotoxicology. The possible reasons for this are discussed e.g., different data types, the potential to mask effects, and the lack of guidance. These concerns are real but not insurmountable and we would like to see organisations such as OECD, EFSA and USEPA develop guidance on the principles of HCD collection. Hopefully, this would lead to greater use of HCD and regulatory acceptance. We believe this is not only a scientifically valid approach but also an ethical issue that is in line with societally driven legal mandates to minimise the use of vertebrate testing in chemical regulatory decision making.

Multiyear monitoring of bird communities in chlorpyrifos-treated orchards in Spain and the United Kingdom: Spatial and temporal trends in species composition, abundance, and site fidelity.

The relationship between agricultural practices and the welfare of wild birds has gained increased attention over the last decades. To assess the potential effects of chlorpyrifos on the bird community, a multiyear, multisite monitoring program was carried out in treated cider orchards (in the United Kingdom) and treated citrus orchards (in Spain). Constant-effort mist netting was used over several consecutive years in the United Kingdom (2012-2014) and Spain (2010-2012). The general structure of the bird community and the presence of breeding species were analyzed. Twelve and 11 bird species (out of 81 and 45 trapped) in Spain and the United Kingdom, respectively, exceeded the 2% dominance value. For a selection of 6 species in citrus and 4 in cider orchards, N-mixture models were fitted to the number of trapped birds. The abundance of most species was strongly and significantly affected by seasonality. No species showed any indication of reduction in population size over the years. The results of this extensive field program support the indications that chlorpyrifos spray applications present a low risk to the bird community over the years. Environ Toxicol Chem 2019;38:616-629. © 2018 The Authors. Environmental Toxicology and Chemistry Published by Wiley Periodicals, Inc. on behalf of SETAC.

An avian reproduction study historical control database: A tool for data interpretation.

Avian reproduction studies are a regulatory requirement for pesticides in many regions. The data often require careful interpretation due to the nature of the study design. Here we present the historical control dataset for bobwhite quail and mallard duck reproduction studies performed at the Evans Analytical Group LLC avian toxicology laboratory over the period 1985-2016. The analysis demonstrates the stability of reproductive parameters over time and good agreement to normal control ranges as required by the regulatory test guidelines. The major source of variation is shown to be within study variation. Power analyses confirm the generally good power properties of the test design. Recommendations for the use of historical control data for the interpretation of avian reproduction studies are made. We believe the analysis and evaluation presented here can facilitate the development of practical guidance that can be implemented in regulatory programmes requiring this test.

Japanese quail acute exposure to methamidophos: experimental design, lethal, sub-lethal effects and cholinesterase biochemical and histochemical expression.

We exposed the Japanese quail (Coturnix coturnix japonica) to the organophosphate methamidophos using acute oral test. Mortality and sub-lethal effects were recorded in accordance to internationally accepted protocols. In addition cholinesterases were biochemically estimated in tissues of the quail: brain, liver and plasma. Furthermore, brain, liver and duodenum cryostat sections were processed for cholinesterase histochemistry using various substrates and inhibitors. Mortalities occurred mainly in the first 1-2h following application. Sub-lethal effects, such as ataxia, ruffled feathers, tremor, salivation and reduced or no reaction to external stimuli were observed. Biochemical analysis in the brain, liver and plasma indicates a strong cholinesterase dependent inhibition with respect to mortality and sub-lethal effects of the quail. The histochemical staining also indicated a strong cholinesterase inhibition in the organs examined and the analysis of the stained sections allowed for an estimation and interpretation of the intoxication effects of methamidophos, in combination with tissue morphology visible by Haematoxylin and Eosin staining. We conclude that the use of biochemistry and histochemistry for the biomarker cholinesterase, may constitute a significantly novel approach for understanding the results obtained by the acute oral test employed in order to assess the effects of methamidophos and other chemicals known to inhibit this very important nervous system enzyme.