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We are heading to Portland, Oregon, to participate in the 46th Annual Meeting of the Society of Environmental Toxicology and Chemistry (SETAC) North America, taking place from November 16 to 20, 2025.

Our employee-owners are proud to be deeply involved with this organization and event. This year, we are scheduled to co-lead a workshop, share three oral presentations, and chair a session on assessing risks to non-target arthropods. Scott Teed, a Stone ecotoxicologist, was also named to the SETAC Board of Directors in September. If you're also attending, join us for one of our presentations or contact Scott Teed, Dwayne Moore, or Alan Samel directly to set up a time to connect.

Click here to register and learn more. 

   

Workshop 

PT04 Aquatic Organisms for Toxicity Tests — Study Design, Test Methods, Challenges, Data Interpretation and Special Topics

Time: 8:30 a.m. to 5 p.m., PDT, Sunday, November 16, 2025

Location: Oregon Convention Center, Room TBD

Coordinated by Alan Samel (Stone Environmental) and James Lazorchak, US EPA

Abstract: Aquatic organisms represent a diverse and important ecological group that is tested under laboratory conditions and frequently in the field to address many different regulatory requirements. For example, under the U.S. regulatory frameworks for effluent and receiving waters, the “core” studies are acute studies with the cladocerans Daphnia magna, D. pulex, and Ceriodaphnia dubia, the fathead minnow (Pimephales promelas) and the green algal species Raphidocelis subcapitata. The chronic laboratory test is with C. dubia. Sediment tests with the midge (Chironomus dilutus) and the amphipod (Hyalella azteca) are often required. There are similar requirements for conducting aquatic toxicity tests for pesticide registration. We will discuss these core tests, then focus on the non-standard organisms to provide state-of-the-science knowledge for ecotoxicological testing. We will focus on the challenges for culturing and maintaining these organisms and conducting toxicity tests when no standard toxicity method is available, and how the study results are used in the regulatory process. The objectives of the special topics are to provide attendees with an introduction to areas where aquatic organisms play an important role and to give attendees a flavor of topics that will be presented at the SETAC meeting in platform and poster sessions that week. The special topics segment may include the U.S. Endangered Species Program, New Approach Methods (NAMs), metals, population modeling, and endocrine disruption. 

Sessions and Presentations

Session: Almost All Things Related to Endangered Species Assessment

Date/Time: Tuesday, November 18, 2025 (10 am to noon)

Location: Oregon Convention Center, Level 1, A105-106

Chairs: Twyla Michelle Blickley, Joshua Arnie

Description: Endangered and threatened (i.e., listed) species assessment for pesticides has been rapidly evolving since January 2022 when the U. S. Environmental Protection Agency announced its intention to meet its obligations under the Endangered Species Act (ESA) for new active ingredients. Today biological evaluations for both new and registration review molecules have increased in complexity with updated and/or higher tier exposure models/scenarios, a new assessment paradigm for non-target arthropods other than bees and inclusion of the ""strategies"" magnitude of difference approach. Furthermore, there has been work on novel laboratory testing methods in more representative surrogates, methodological refinements in both species and exposure assessment, generation of spatial data layers for non-agricultural uses, studies on the effectiveness of field-level mitigations and more. This session is designed to include a broad assortment of presentation topics associated with advances in endangered species assessment and pesticides (conventional and biologicals), as well as plant incorporated protectants (seeds/traits) and complement the special session on ESA implementation.

Presentation: Improving Endangered Species Pesticide Risk Assessment and Mitigation Evaluation With Geospatial Aquatic Exposure Modeling Refinement (10:40 to 11:00 am, PDT)

Presenter: Scott Teed, (Stone Environmental). Authors: Mike Winchell, Hendrik Rathjens, Scott Teed (Stone Environmental), Christopher Holmes, Lula Ghebremichael, Jessica Chen, Tilghman Hall, Rebecca Haynie, Ralph Warren, Patrick Havens, Paul Whatling

Abstract: New strategies for efficiently conducting endangered species pesticide risk assessments and determining necessary mitigations for reducing pesticide exposure have been developed by the US EPA, including distinct strategies for herbicides, insecticides, and rodenticides. These strategies have purposefully relied upon conservative screening-level exposure modeling methods and assumptions, both for efficiency and to help ensure species protection. In the case of aquatic exposure, this high level of conservatism consequentially leads to very high levels of exposure reductions needed to meet species protection goals, often 99% (100x) or greater. These screening-level exposure estimates lead to both a mischaracterization of pesticide use risk and may misinform where and to what extent mitigations are potentially needed to protect species. An alternative approach is to incorporate aquatic exposure modeling methods that account for local environmental conditions and agronomic practices into the risk assessment process. This leads to more realistic species-specific exposure estimates and resulting risk characterization and mitigation strategies. We will demonstrate a multi-step aquatic exposure modeling methodology designed for national endangered species assessments that incorporates four key geospatial refinement elements: Geographically-explicit exposure scenarios, Percent Cropped Area, pesticide use site proximity to aquatic habitat, and Percent Crop Treated. The methodology, designed to be both flexible and efficient, has been tested for the insecticide dimethoate and compared with the exposure, risk assessment, and mitigation requirement results from a dimethoate case study conducted following the US EPA’s Insecticide Strategy. The new methods resulted in species-specific exposure estimates substantially lower than the generalized screening-level exposure estimates from the Insecticide Strategy, leading to more realistic risk characterization and the potential for a more effective mitigation approach. The exposure modeling methodology developed in this assessment can be readily applied to endangered species risk assessments for other pesticides and can be extended when updated datasets (e.g., crop location spatial layers or pesticide usage) become available.

Session: Assessing Risks to Non-Target Terrestrial Invertebrates: Current Status and Future Refinements

Date/Time: Thursday, November 20, 2025 (1:30 to 3:30 pm, PDT)

Location: Oregon Convention Center, Level 1, A105-106

Chairs: Alan Samel, (Stone Environmental) Dwayne Moore (Stone Environmental), Valery Forbes, Stefan Kroder

Description: There has recently been a global push to better assess and understand the risks of pesticides to non-target arthropods (NTAs) and other non-target terrestrial invertebrates. Currently, most risk assessments rely on toxicity endpoints from acute and chronic non-native honey bee (Apis mellifera) tests to assess risk to all NTAs and other invertebrates potentially at risk from exposure. For insecticides, toxicity endpoints from contact tests involving the parasitic wasp (Aphidius rhoplosophi) and the predatory mite (Typhlodromus pyri) are also included in Tier 1 NTA risk assessments. NTAs and other invertebrates represent a vast and diverse array of taxonomies and functional groups including detritivores, herbivores, omnivores, carnivores, parasitoids and pollinators. On the exposure side, off-field risks are typically estimated with simple 2D spray drift models that do not consider receiving habitat (e.g., forests, meadows, wetlands) or where different NTAs forage (e.g., high, mid, and low canopy, soil surface, soil). Risks to NTAs and other invertebrates occurring via changes to their habitat or diet, as could arise from herbicide use, are rarely considered. There are currently more than 210 threatened and endangered NTA and other terrestrial invertebrate species in the United States, including many snails, beetles, crickets, dragonflies, damselflies, bees and butterflies. Thus, there is a critical need to develop and refine the approaches and available tools for determining pesticide risks to NTAs and other terrestrial invertebrates. The objectives of the session will be: (1) provide a review of the current global approaches to NTA and other invertebrate risk assessments during pesticide registration and under the endangered species act; (2) provide reviews of currently available tools (e.g., exposure models, population models, toxicity endpoints); (3) present tools that are currently in development (e.g., 3D drift models, additional toxicity test species, surrogacy, field studies, population and community models); and (4) present case studies demonstrating the use of current and new approaches and tools, and o Identify short-term and long-term programmatic and research needs.

Presentation: Current State of the Practice for Pesticide Risk Assessments Involving Non-Target Arthropods (1:30 to 1:50 pm, PDT)

Author: Dwayne Moore (Stone Environmental)

Abstract: Non-target arthropods (NTAs) play a pivotal role in ecosystems, including maintaining biodiversity, regulating pest populations, providing pollination services, serving as food for other organisms, nutrient cycling, and many others. Insecticides are applied to agricultural and non-agricultural landscapes to control target pest insect species and thus can affect NTAs that occur in treated areas or areas to which insecticides may be transported. Other pesticides (e.g., herbicides) can affect NTAs by reducing food availability or changing their habitats. In recent years, various jurisdictions have been developing risk assessment frameworks and methods for assessing the risks of pesticides to potentially exposed NTAs. Assessing risk to NTAs must account for various exposure routes (e.g., contact via direct spray, foliar and soil contact, dietary and drinking water consumption, guttation) arising from where different NTAs are found and how they forage and reproduce (e.g., on or off treated areas, flying, on top of or under foliage, soil surface, sub-surface). Further, different life-stages may have quite different routes of exposure (e.g., caterpillars vs butterflies, nurse bees versus forager bees). Finally, sensitivity can vary dramatically among NTAs. Currently, most pesticides only have toxicity data for a limited number of test species (honeybees, parasitoid wasp, predatory mite) and exposure routes (contact, diet). New test species and methods are being developed and have been used in some NTA assessments (e.g., bumblebee, green lacewing, seven-spot ladybird, rove beetle). Higher tier semi-field and full-field study methods are also becoming part of the risk assessment toolbox. In this presentation, I will discuss the current state of the practice for assessing direct and indirect risk of pesticides to NTAs. Recommendations for future improvements to existing frameworks and methods will also be made.

Presentation: Using Artificial Intelligence and Brute Force to Identify Diversity of Laboratory Non-Target Arthropod Toxicity Tests and the Diversity of Non-Target Arthropods Tested (2:10 to 2:30 pm, PDT)

Author: Alan Samel (Stone Environmental)

Abstract: Currently, Non-Target Arthropod (NTA) testing in the laboratory for regulatory purposes is limited to very few terrestrial species (e.g., honey bee, bumble bees, parasitoid wasp, predatory mite). These and a few other species are used to represent the thousands of NTAs around the world. In the United States, there are approximately 120 NTAs that are identified as endangered species. These include aquatic and terrestrial organisms that include mussels and snails, shrimps and other arthropods, aquatic insects, butterflies, bees and beetles. Exposure pathways can include direct contact, consumption of plant foliage, consumption of nectar, predation or parasitism of prey organisms that already have pesticide residues from previous exposure(s) and/or contact with soil. To determine if additional species were being evaluated in laboratory toxicity tests conducted outside the pesticide regulatory process, artificial intelligence (AI) was used to determine the NTAs tested, and the types of tests conducted. Thorough and exhaustive literature searches were then conducted to further identify study designs and test organisms. The objective of the project was to identify laboratory toxicity tests with organisms outside the normal regulatory process that could be applied to the endangered species risk assessment. I will discuss the process used to identify potential toxicity tests that could be used to gain a better understanding of the potential sensitivity of endangered NTAs to pesticides.