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Publications: Crop Protection

PresentationsCrop Protection2020

An Overview of Key Features of Population Models and Their Relevance for Ecological Risk Assessment

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Session Title: 5.06 – Environmental Effects Modeling: Advances in Development and Application of Effects Models in Environmental Risk Assessment
SciCon2 5.06.01

Abstract:

The last two decades have seen substantial advances in the development of population models for the ecological risk assessment (ERA) of chemicals. These include guidance on systematic and consistent model creation and documentation, model evaluation and testing, and choosing models of appropriate complexity to address different types of risk assessment questions. A growing collection of case studies has clearly demonstrated how such models can inform risk assessment and risk management decisions, and slowly but surely there are indications that the acceptance of population models for ERA will continue to increase. Nevertheless, there remain misconceptions about population models for ERA, including confusion regarding differences among types of model formalization (e.g., differential equation, matrix or agent-based models), uncertainty surrounding the implications of including or ignoring different aspects of reality in the models, as well as a lack of consensus on the role that the models should play in the ERA process. We provide an overview of the key features that may be included in population models to inform ERAs. They include density dependence, spatial variability, external drivers, stochasticity, life history, behavior, energetics and how exposure and effects are integrated in the models. We consider why these features are relevant for ERA and how they can be incorporated into three broadly defined population model categories: unstructured, structured, and agent-based. We show that nearly all features can be included in all model categories, but some features are more or less easily incorporated in certain model types. Using a previously published database of population models, we assessed the frequency with which each of the key features has been included so far in the different model categories. We show that some features have been more strongly associated with a certain model category. The aims of the overview are to help model developers and model evaluators assess the extent to which a model and its features are fit for purpose and to increase the consistency and transparency of population models used for ERA.

C. Accolla (University of Minnesota), M. Vaugeois (University of Minnesota), V. Grimm (Helmholtz Centre for Environmental Research – UFZ), A. Schmolke (Waterborne), A. Moore (University of Minnesota), P. Rueda-Cediel  (University of Minnesota), V. Forbes (University of Minnesota)

An Overview of Key Features of Population Models and Their Relevance for Ecological Risk Assessment. SciCon2 5.06.01, SETAC 2020 Virtual Meeting.

PresentationsCrop Protection2020

Assessing the Risks of Pesticides to Terrestrial Threatened and Endangered Species: Opportunities to Refine Risk Assessments for Listed Terrestrial Plants

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Session Title: 5.04 – Endangered Species Assessments for Pesticides
SciCon2 5.04.14

Abstract:

There is a continuing need to develop improved procedures and tools for assessing pesticide risks to threatened and endangered (i.e., listed) species in the United States. As part of meeting this challenge, the TERrestrial Endangered Species Assessment (TERESA) model was developed following a tiered approach to efficiently evaluate potential pesticide exposures and risks to listed terrestrial species. The terrestrial plant version of TERESA includes the ability to evaluate risks to listed plant species based on direct effects or potential indirect pathways (e.g., effects to insect pollinators or obligate symbionts). For species that are not screened out in the first tiers of the analysis in TERESA, various refinements can be conducted to better characterize risk using information about the species and relevant product use patterns. We conducted refined case studies for a subset of listed terrestrial plant species potentially exposed to a representative insecticide. Multiple lines of evidence were evaluated including refined spatial exposure estimates based on product use information and species life history and characteristics that may influence exposure potential. Factors considered in these analyses include local use conditions, application rates and methods, temporal relationships between species and application timing and species habitat associations. Given the low direct toxicity of this pesticide to terrestrial plants, the focus is on illustrating an approach to evaluate risk to biological features upon which the listed plant species depends. The case studies highlight the importance of bringing together the most reliable and relevant information to reduce uncertainty and improve our understanding of pesticide risk to listed species.

M. Kern (Balance EcoSolutions LLC), N. Green (Waterborne), N. Snyder (Waterborne), D. Moore (Intrinsik), S. Teed (Intrinsik), C. Priest (Intrinsik), H. Rathjens (Stone Environmental), M. Winchell (Stone Environmental), T. Blickley (Eurofins EAG Agroscience Services LLC)

Assessing the Risks of Pesticides to Terrestrial Threatened and Endangered Species: Opportunities to Refine Risk Assessments for Listed Terrestrial Plants. SciCon2 5.04.14, SETAC 2020 Virtual Meeting.

PresentationsCrop Protection2020

A Tiered Approach to Efficient Refinement of Aquatic Exposure Assessments for Endangered Species

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Session Title: 5.04 – Endangered Species Assessments for Pesticides
SciCon2 5.04.08

Abstract:

Quantitative pesticide exposure and risk modeling is a powerful tool to effectively and efficiently make the important distinction between threatened and endangered species that are likely to be and not likely to be adversely affected (LAA and NLAA, respectively) as a resulted of a pesticideís labeled uses. To achieve efficiency and transparency in such assessment for aquatic species, progressive steps in exposure modeling are needed that employ the best available datasets and scientific approaches to introduce meaningful and substantial refinements. We have developed a multi-tiered approach for aquatic exposure modeling designed to meet these requirements for national scale endangered species risk assessments. The approach begins with Tier 1 which is highly conservative and represents potential high-end exposure for all species. Tier 1 accounts for a wide range of potential use patterns, cropping scenarios, application dates, and weather conditions. At Tier 2, much greater relevance of the exposure estimates for each species is achieved by accounting for the spatial overlap between pesticide exposure scenarios and species ranges and critical habitats. In Tier 2, two additional refinement steps are incorporated into the exposure modeling. The first refinement accounts for potential pesticide use sites, or percent cropped area (PCA), in estimating exposure concentrations in multiple static and flowing aquatic habitat types. PCA for large numbers of relevant water bodies within a species range are analyzed using GIS datasets and processing techniques. The second refinement step in Tier 2 is based on best available pesticide usage data. Usage data are analyzed probabilistically to generate an ensemble of pesticide usage scenarios across the US and overlaid with species ranges. This pesticide usage data refinement step results in quantitative pesticide exposure probability distributions that are then incorporated into risk assessment decisions. The two-tier methodology developed is an efficient, effective, and transparent process using best available data and scientific analysis methods that helps guide a risk assessor to making NLAA/LAA decisions in national endangered species risk assessments.

M. Winchell (Stone Environmental), H. Rathjens (Stone Environmental), S. Castro-Tanzi (Stone Environmental), J. Dunne (Stone Environmental), N. Snyder (Waterborne), P. Havens (Corteva Agriscience)

A Tiered Approach to Efficient Refinement of Aquatic Exposure Assessments for Endangered Species. SciCon2 5.04.08, SETAC 2020 Virtual Meeting.

PresentationsCrop Protection2020

Assessing the Risk of Pesticides to Threatened and Endangered Species: Developments of Process and Tools

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Session Title: 5.04 – Endangered Species Assessments for Pesticides
SciCon2 5.04.02

Abstract:

In the United States, registration of a pesticide is considered a Federal action and, as such, requires a review of potential impacts to threatened and endangered species (listed species) and their designated critical habitats under the Endangered Species Act (ESA). There are over 1600 listed species in the United States, multiple use sites for each pesticide active ingredient, and three agencies (the US Environmental Protection Agency (EPA), Fish and Wildlife Service (FWS), and National Marine Fisheries Service (NMFS), collectively ìthe Agenciesî) involved in each assessment. Thus, an endangered species risk assessment (ESRA) for a pesticide is an enormous undertaking. Although there has been progress towards developing more efficient and scientifically defensible approaches for pesticide ESRAs, continuous improvement in these methods is required. This presentation describes investigations into the development of ever more efficient, transparent, reproducible, and sustainable ESRA processes for pesticides, including the development of innovative and user-friendly new tools. We illustrate these developments with case studies involving representative insecticide, herbicide and fungicide chemistries. Subsequent presentations in this session will describe many of the tools and approaches that were developed as part of this work.

D. Moore (Intrinsik), T. M. Blickley (Corteva Agriscience), L. Brewer (Compliance Services International), A. Frank (Compliance Services International), J. Giddings (Compliance Services International), P. Havens (Corteva Agriscience), M. Kern (Balance EcoSolutions LLC), C. Priest (Intrinsik), B. McGaughey (Compliance Services International), H. Rathjens (Stone Environmental), N. Snyder (Waterborne), R.S. Teed (Intrinsik), M. Whinchell (Stone Environmental)

Assessing the Risk of Pesticides to Threatened and Endangered Species: Developments of Process and Tools. SciCon2 5.04.02, SETAC 2020 Virtual Meeting.

PresentationsCrop Protection2020

Coupling PRZM with SWAT for Ecological Risk Assessment of Agricultural Pesticides

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Session Title: 4.03 – Exposure: Processes and Approaches for Estimating Environmental Exposures
SciCon2 4.03.10

Abstract:

Ecological risk assessment for the regulatory compliance of agricultural pesticides requires determination of potential exposure levels in receiving water bodies to which aquatic organisms may be exposed. Modeling and monitoring approaches are key methods used in determining pesticide exposure levels, length and frequency of occurrences. In this study, we present a modeling framework involving a conjunctive use of the field-scale PRZM and watershed-scale SWAT environmental models. The use of PRZM-SWAT modeling framework allowed to leverage PRZM is detailed field-level representation of pesticide fate and transport processes and SWAT is key hydrological and biogeochemical attenuation processes between edge of field losses and loss in water moving from the field into surface water networks. The PRZM-SWAT modeling framework was calibrated using a Monte Carlo approach to stream flow and a 4-, 7-, 21-, 30-, and 60-day maximum annual rolling average exposure durations, that are of significance to the ecological risk assessments. The performance of the model was evaluated using 8-year monitoring of atrazine data and stream flow from a high use-intensity, headwater watershed in Missouri. This presentation will describe the modeling framework, calibration approaches, and results of the modeling performances.

L. Ghebremichael (Syngenta), W. Chen (Syngenta), A. Jacobson (Waterborne), C. Roy (Waterborne)

Coupling PRZM With SWAT for Ecological Risk Assessment of Agricultural Pesticides. SciCon2 4.03.10, SETAC 2020 Virtual Meeting.

PresentationsCrop Protection2020

A Dfop-Based PRZM Model to Predict Non-First Order Degradation and Subsurface Transport in Soil and Groundwater

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Session Title: 4.03 – Exposure: Processes and Approaches for Estimating Environmental Exposures
SciCon2 4.03.02

Abstract:

Many soil metabolism and other environmental fate studies have observed non-first order degradation often in a biphasic pattern with fast initial decline followed by a noticeably slower phase. The decline pattern deviates from the classical simple first-order (SFO) kinetics. Although widely recognized, biphasic degradation has never been directly incorporated into regulatory models. Instead, regulatory modeling policies require an SFO curve fit preferentially to the slow portion of the decline data while largely ignoring the fast initial phase. As a result, modeling errors in the predicted exposure levels in surface and ground waters can be artificially elevated. This paper examines the impact of biphasic degradation on pesticide leaching behavior using a PRZM-based model synPRZM developed by Syngenta and Waterborne. The model directly incorporates the kinetics of Double First-Order in Parallel (DFOP) to account for the complete biphasic decline profile. Sensitivity analysis of synPRZM shows that the model converges to the same results of the original PRZM model when the kinetics fit is SFO. When the kinetics shows DFOP characteristics, synPRZM can represent biphasic degradation better. Using DFOP, synPRZM was able to predict several field soil residue data sets reasonably well without elaborated model calibration. Predicted soil pore water concentrations from synPRZM are also compared with measured data from field lysimeters. The overall model performance suggests synPRZM can be used as a predictive tool to handle biphasic degradation behavior frequently observed in pesticide field studies. The inherent nature of DFOP reflecting the rate-limiting effect of time-dependent sorption on biodegradation is also examined for the soil-pore water system.

W. Chen (Syngenta), M. Cheplick (Waterborne), D. Mao (Waterborne)

A Dfop-Based PRZM Model to Predict Non-First Order Degradation and Subsurface Transport in Soil and Groundwater. SciCon2 4.03.02, SETAC 2020 Virtual Meeting.

PresentationsCrop Protection2020

Towards an efficient and improved approach for assessing risks of pesticides to endangered species in the United States: Methomyl case study

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ACS 2020, AGRO 178
Session Title: Integrating Species Conservation with Pesticides from Bench to Market
Available Monday, August 17, 2020 at 8:00am

Abstract:

Under the Endangered Species Act, the US Environmental Protection Agency (EPA) and the Services (National Marine Fisheries Service and Fish & Wildlife Service) are required to assess potential risks to threatened and endangered (listed) species as part of the process to register pesticides. EPA issued interim guidance for developing biological evaluations (BE) for pesticides in 2015. Since then, the EPA, the Services, the regulated community and others have continued to develop and refine national endangered species risk assessment (ESRA) methodologies, first with 3 organophosphates and recently with two carbamates, carbaryl and methomyl. In March 2020, EPA issued revised guidance for conducting BEs. Much, however, remains to be done to develop the most efficient, practical and scientifically defensible approach. Therefore, we are developing an improved scientific approach with methods that more efficiently screen out listed species that are not at risk earlier in the tiered assessment process. The approach begins with simple methods such as off-ramping (e.g., screening out listed species that have no potential for exposure); conservative, protective screening-level risk assessments to screen out entire receptor groups that are tolerant of exposure; and co-occurrence analyses to screen out species not present in pesticide use areas. We are developing spatially explicit, species-specific tools for each major receptor group to determine which listed species are potentially at risk using more advanced, but still protective, methods. Using methomyl as a case study, we demonstrate how these early tier methods can efficiently reduce the formidable scope of a national ESRA to focus on those listed species most at risk. The latter species would then proceed to probabilistic, more refined modeling and proper weight-of-evidence assessments.

D. Moore (Intrinsik), S. Teed (Intrinsik), C. Priest (Stone), M. Winchell (Stone), H. Rathjens (Stone), A. Frank (CSI), J. Giddings (CSI), M. Kern (Balance EcoSolutions), N. J. Snyder (Waterborne), T.M. Blickley (Corteva Agriscience), P.L. Havens (Dow AgroSciences).
Towards an efficient and improved approach for assessing risks of pesticides to endangered species in the United States: Methomyl case study. AGRO 178, ACS 2020. Virtual Meeting.

PresentationsAgriculture and Food, Crop Protection2020

Impact of climate change on the relevance of TFD studies and OECD crosswalks

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ACS 2020, AGRO 235
Session Title: Sustainability in Agriculture: Understanding the Environmental Footprint of Developing Crop Protection Products
Monday, August 17, 2020 8:00AM

Abstract:

Climate change studies confirm that the earth is warming up and that shifts in rainfall patterns is occurring. Various computer models predict that Earth’s average temperature will rise between 1.8° and 4.0° Celsius (3.2° and 7.2° F). Consequently, these warmer temperatures will cause a higher rate of evaporation, resulting in a predicted increase of average global rainfall by 3-5%. This climate change, therefore, will impact the relevance of historical and current terrestrial field dissipation (TFD) studies. Under OCED guidance, TFD studies conducted in one country can be applicable to other countries if the characteristics of overlapping ecoregions are the same. These assessments are conducted using the OECD ENASGIPS tool. If these characteristics change, so will the similarity assessment and therefore the potential relevance of TFD sites. With increase rainfall, TFD sites in the Southeastern US, which typically have few similar areas, may become more relevant because other areas are receiving more rainfall. Likewise, TFD sites in Canada, characterized by cold winters, may become more applicable to larger areas in Europe with increasing temperature. In this presentation we will review some of the climate change scenarios, place existing TFD sites in context of new climates and determine the impact on OECD crosswalks.

C. Hoogeweg, A. Ritter (Waterborne). Impact of climate change on the relevance of TFD studies and OECD crosswalks. AGRO 235, ACS 2020. Virtual Meeting

PresentationsAgriculture and Food, Crop Protection2020

Novel approaches for assessing management of tile-drain agricultural chemical transport

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ACS 2020, AGRO 214
Session Title: Off-target Transport of Field Applied Agricultural Chemicals
Monday, August 17, 2020 8:00AM

Abstract:

The study of conservation best management practices and their effectiveness at mitigating the off-site transport of agricultural chemicals is an established research field. While runoff and erosion have received much study focus, there is a growing need for new and novel approaches to monitor nutrients in tile-drained systems. A sophisticated water monitoring system was developed that utilizes technology to create an automated pass-through sampling site, employing state of the art nutrient sensor technology to monitor nitrate concentrations in thirty-seven discrete subsurface agricultural drainage tile laterals at a sampling rate of between two and four hours per sample at each tile. This design has proven highly efficient and provides a data resolution that would be impractical to consider under conventional sampling methods. It also allows for the replicated study of several treatments (different mitigation practice approaches) and control plots, with little additional cost per added plot. Additional benefits include the ability to view data in real-time, allowing researchers to observe real-time rainfall event-based plot responses without the analytical results delay from a laboratory. The developed site data provides the needed resolution for tile drain model validation or developments.

G. Goodwin (Waterborne), L. Gentry (Illinois Corn Growers Association), P. Paulausky, J. Trask, A. Jacobson, A. Ritter (Waterborne). Novel approaches for assessing management of tile-drain agricultural chemical transport. AGRO 214, ACS 2020. Virtual Meeting.

PresentationsCrop Protection2020

Consideration of non-Apis bee species in pollinator risk assessment

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ACS 2020, AGRO 164
Session Title: Extending the Boundaries of Pollinator Research and Risk Assessment Methodologies for Pesticides
Monday, August 17, 2020 8:00AM

Abstract:

The pollinator risk assessment process for pesticides from regulatory agencies, including USEPA, PMRA, and CDPR, have historically relied on the Western honeybee (Apis mellifera) as a surrogate species to represent all Apis and non-Apis bees. However, the life-history characteristics of non-Apis bee species, including solitary, stingless, and bumble bees, indicate differences from the surrogate honeybee species. These differences introduce uncertainty in the exposure and effects assumptions for the use of honeybees as a surrogate species, leading to the recent efforts of examining risk of pesticides to non-Apis species. The objective of this presentation is to provide a current state-of-the-science update on the specific life-history characteristics and specific risk assessment considerations for non-Apis species. Exposure assumptions will be examined and comparative toxicological sensitivities will be presented with recommendations for appropriate use in the pollinator risk assessment framework. Challenges in the development of non-Apis laboratory testing methods will also be presented.

J. Collins, J. Jackson, A. Ritter, A. Schmolke (Waterborne). Consideration of non-Apis bee species in pollinator risk assessment. AGRO 164, ACS 2020. Virtual Meeting.