WATERBORNE EVENTS

Society of Environmental Toxicology and Chemistry (SETAC)

SETAC North America 44th Annual Meeting. Louisville, Kentucky

November 12 – 16, 2023

Join Waterborne Environmental at the upcoming SETAC conference on November 12-16, 2023! We're sending a cotillion of experts who will staff our booth (find us at Booth #54), present short courses and papers (abstracts below), and meet with colleagues within the industry. If you'd like to set up a meeting, please contact Waterborne's SETAC lead, Nathan Snyder, at snydern@waterborne-env.com.

Upcoming Events
Register For SETAC

Waterborne Short Course

5.02.P-Mo-180, Accessing Pollinator Decline Associated Risks to Endangered Plant Populations using Bayesian Networks

Authors: Paul Glaum1, Nathan Snyder1, Matthew E Kern2, Twyla Michelle Blickley3,4 and Patrick Havens5, (1)Waterborne Environmental, Inc., (2)Balance EcoSolutions LLC, (3)Eurofins EAG Agroscience Services, LLC, (4)Corteva Agriscience, (5)Environmental Exposure Assessment, Corteva Agriscience

Why it’s important:

Endangered species can experience risk due to an array of direct and indirect factors, each understood with varying amounts of available data. While the traditional Risk Quotient approach can synthesize this complexity into a tractable single number, it is limited in its ability to address uncertainty and incorporate the structural framework that mediates this risk in nature. Approaches like Bayesian Networks can incorporate conditional probabilities that structure uncertainty both hierarchically and synergistically to obtain evidence-based inference even with limited data. This level of detailed risk assessment can produce a deeper understanding of the sources of risk and potential mitigation options. With our SETAC poster, we apply this framework to endangered plant species experiencing risk based in pollinator loss due to pesticide exposure.

Abstract:

Endangered plant populations experience a wide array of stressors such as habitat loss, competition from invasive species, weather events, fire management practices and other human activities. Insect pollinators play essential or facultative roles in the vast majority of plant species’ reproduction. Studies have shown that concurrent with the pollinator loss, comes a reduction in plant reproduction dependent upon lost pollination services. Endangered plant species already experiencing low densities can be particularly vulnerable to reductions on pollination services. Estimating the effect of pollination loss on plants is challenging because pollination is a function of numerous direct and indirect interactions between ecological factors and management practices. This difficulty is compounded when there is little data describing these drivers and their interactions.  Bayesian Networks provide options for understanding emergent risk from multifaceted processes with limited data. Coupling Bayesian inference with network science, Bayesian Networks are specifically optimized to provide evidence-based inference across complex causal chains, even with limited data. This is supported by: 1) the flexible nature of Bayesian Networks which can make use of relationships between both quantitative and categorical data and 2) the network structure of conditional probability which propagates direct and indirect inference across different types of data. Furthermore, Bayesian Networks are readily updated as better data becomes available to produce inference reflecting the best available data. Here we show how Bayesian Networks can be used to evaluate the risk faced by endangered plant species experiencing potential losses in insect pollination due to insecticide exposure. Using the Bayesian network development software Netica, we created and visualized a Bayesian network describing risk facing endangered plants in southern Florida. We then present sensitivity analysis across network outcomes using the RNetica software package in R to visualize how risk changes as a function of focal species and application practices.

Waterborne Presentations

Monday, November 14th, 10AM - 12:40PM, Session 5.06.T-06; Convention Center – Ballroom A 

Title:  Incorporating Climate Changes Scenarios to Understand Future Water Stress and Modeling its Impact on Consumer Product Chemical Exposure to the Environment. Authors: Raghu Vamshi, Waterborne Environmental, Inc., Brenna Kent, Waterborne Environmental, Inc., Scott Dyer, Waterborne Environmental, Inc. and LeTourneau University, Andrea Carrao, Kao USA, Inc.

Abstract:  Increased demand from a growing human population coupled with expansive evidence of climate change have intensified stresses on water availability and supply. The number of regions experiencing water stress is increasing, and municipalities are grappling with this stress by investing in water conservation, reuse, and recycling technologies. These methods will enable freshwater to be used in water stressed areas, however – they may require innovations in consumer products that are dependent on water for their function and disposal. Water stress in the U.S. was examined by evaluating datasets considering historic, current, and future water availability and use scenarios. Inclusion of anticipated climate change events required datasets that incorporated scenarios of estimated future population and per capita water use with high spatial resolution for the U.S. These datasets captured predicted temporal trends for the years 2020-2050 and were integrated with EPA’s Clean Water Needs Survey data, which represents municipal wastewater treatment plant infrastructure across the U.S. The consolidated information was used to develop current and future water use scenarios. The influence of future water use scenarios on down-the-drain chemical exposures were predicted by evaluating four consumer product chemicals with various phys/chem properties. Results from the modeling provided a quantitative forecast of the potential impacts of water stress on down-the-drain chemical exposure and potential risk. Incorporating spatial and temporal variation in water stress and its impact to the risk of chemicals in the environment, through the lens of future scenarios, provides a new dimension in the development of consumer products. Incorporating these issues into product development, now, will ensure that both consumers and the environment will be appropriately stewarded, especially considering future environmental challenges.

1.14.P-Tu-055, The Development of the MERCI Modeling Framework to Evaluate the Exposure of Sunscreen and Cosmetic Ingredients to Marine and Freshwater Ecosystems

Authors: W. Martin Williams1, Scott Dyer1,2, Todd Gouin3, Nicola Hefner4, Eva Klingelmann5, Amelie Ott6, Sascha Pawlowski7 and Maura Roberts1

(1)Waterborne Environmental, Inc., (2)LeTourneau University, (3)TG Environmental Research, United Kingdom, (4)DSM Nutritional Products Ltd, Switzerland, (5)Symrise AG, Germany, (6)Cosmetics Europe, Belgium, (7)GBP/RA, BASF SE, Germany

Why it’s important:

The MERCI tiered modeling framework consists of suite of models and scenarios to evaluate the direct release of cosmetic ingredients to the environment. The framework is designed to identify if a chemical may cause adverse effects to aquatic ecosystems initially with minimal effort and often with sparse information. Progressive tiers introduce additional processes and complexity to improve the accuracy of predictions. This progression allows risk assessors in industry and regulatory agencies to expend resources only when necessary, and it provides guidance on specific studies that may help improve that accuracy. The framework was initially developed to evaluate the potential exposure of UV filters to coral from the wash-off of sunscreens in populated beach settings, but the models and scenarios are applicable to the direct release of most any constituent (e.g., fertilizers, biocides, preservatives, fragrances, wastewater) to near-shore waters.

Abstract:

A tiered modeling framework has been proposed and tested to evaluate the potential environmental exposure of sunscreen ingredients to marine and freshwater organisms. The framework consists of several levels of assessment ranging from simple dilution-based estimates to complex 3-dimensional circulation models. The tiers permit an initial conservative screen of a chemical with minimal effort and often with sparse information. Progressive tiers introduce additional processes and complexity to improve the accuracy of predictions. Specific models are proposed for each tier based on the environmental fate processes represented by that model, the governing equations and transparency of model code, input parameter requirements, acquisition cost, and established acceptance by regulatory agencies. Model testing involved comparing predictions of chemical concentrations to measured values reported in three monitoring studies. The studies monitoring studies were selected based on the robustness of monitoring data, the availability of information on beach attendance and UV filter use, and availability of information on bathymetry, currents and water/sediment properties, and to represent a variety of environments - shoreline beach, a poorly flushed cove, and a freshwater lake. This presentation describes the framework, the results of model testing including a sensitivity analyses to identify the relative importance of model inputs, guidance for input parameter selection, and descriptions model scenarios that are being considered to evaluate current and future UV filter ingredients.

4.25.P-Tu-188, Refining environmental exposure assessments for consumer-use down-the-drain ingredients using spatially resolved datasets and surface water flow modeling: Focus on Europe  

Authors: Susan A. Csiszar 1, Ryan Heisler2, Chiara Maria Vitale1, Brenna Kent3, Raghu Vamshi3, Amy Ritter3, Kathleen McDonough1

(1)The Procter & Gamble Company, (2)American Cleaning Institute, (3)Waterborne Environmental, Inc

Why it’s important:

Ensuring a healthy environment for the future is a priority for manufacturers and ingredient suppliers of formulated consumer products. Therefore, the ability to determine the potential exposure from down-the-drain products into wastewater treatment plants then into receiving waterbodies is important. This poster shows the iSTREEM® model expansion that can provide estimated river concentration distributions for Europe.

Abstract:

A key aspect to understanding the safety of consumer use down-the-drain (d-t-d) ingredients is environmental exposure assessment in receiving waters. A global framework to estimate d-t-d substance concentrations in river catchments across the globe that leverages large spatial datasets on population, wastewater treatment (WWT) infrastructure, per capita water use, river connectivity, and river flow has been developed and demonstrated for several countries. This framework was built on the well-established iSTREEM® model for the United States and provides estimated river concentration distributions based on spatial variability of these parameters, as well as chemical-specific properties such as WWT removal and in-stream decay. We present the model expansion to Europe which leverages official European Union data on wastewater generation and WWT infrastructure and connectivity, including geographic locations of wastewater treatment plants (WWTP). The river flow data are based on a global hydrological dataset developed as part of this project, that uses high-resolution spatial data on land cover, precipitation, and river connectivity. The resulting distributions of WWT infrastructure, connectivity, and wastewater generation were consistent with values reported for Europe. Chemical case studies on common substances used in consumer d-t-d applications such as laundry detergents and personal care products were used to demonstrate the model and to compare to monitored values across Europe. Modeled values were in good agreement with monitored values and the model was able to capture spatial variation in concentration distributions. Spatially resolved exposure models are a valuable tool in prospective environmental safety assessments providing concentration distributions across modeled regions.

Waterborne Short Course

Sunday, November 13th, 1 - 5PM – Convention Center – 303

Training Course 08: Down-the-Drain Disposal: Environmental Exposure and Risk Assessment for Formulated Consumer Products. Chairs: Ryan Heisler, American Cleaning Institute, Raghu Vamshi, Waterborne Environmental, Inc.

Abstract: Formulated household and personal care products have become omnipresent, with our reliance on many of these products for long-term health, comfort, and safety. These products have also garnered the attention of regulators and researchers because of their widespread use and disposal. The chemical safety of formulated consumer products is a high priority for product manufacturers and ingredient suppliers who seek to ensure a clean and healthy future. One accepted method used to ensure the environmental safety of formulated products is applying risk assessments based on chemical hazards and their potential exposure. 

Potential exposure estimations include environmental (ecological) exposures through releases to aquatic environments, air, or soil. This short course aims to detail the methods used by product manufacturers and regulators to assess environmental exposures associated with formulated consumer products such as home and personal care products to understand related risks of their disposal, post-use, into the aquatic environments, i.e., U.S. surface waters. The focus will be on the fundamentals of risk assessment, emphasizing tiered aquatic environmental exposure assessment. Applications will include both lower (Tier I) and higher tier (Tier II) probabilistic modeling of environmental exposures in aquatic environments across regional and national geographies.

Waterborne Presentations

Monday, November 14th, 10AM - 12:40PM, Session 5.06.T-06; Convention Center – Ballroom A 

Title:  Incorporating Climate Changes Scenarios to Understand Future Water Stress and Modeling its Impact on Consumer Product Chemical Exposure to the Environment. Authors: Raghu Vamshi, Waterborne Environmental, Inc., Brenna Kent, Waterborne Environmental, Inc., Scott Dyer, Waterborne Environmental, Inc. and LeTourneau University, Andrea Carrao, Kao USA, Inc.

Abstract:  Increased demand from a growing human population coupled with expansive evidence of climate change have intensified stresses on water availability and supply. The number of regions experiencing water stress is increasing, and municipalities are grappling with this stress by investing in water conservation, reuse, and recycling technologies. These methods will enable freshwater to be used in water stressed areas, however – they may require innovations in consumer products that are dependent on water for their function and disposal. Water stress in the U.S. was examined by evaluating datasets considering historic, current, and future water availability and use scenarios. Inclusion of anticipated climate change events required datasets that incorporated scenarios of estimated future population and per capita water use with high spatial resolution for the U.S. These datasets captured predicted temporal trends for the years 2020-2050 and were integrated with EPA’s Clean Water Needs Survey data, which represents municipal wastewater treatment plant infrastructure across the U.S. The consolidated information was used to develop current and future water use scenarios. The influence of future water use scenarios on down-the-drain chemical exposures were predicted by evaluating four consumer product chemicals with various phys/chem properties. Results from the modeling provided a quantitative forecast of the potential impacts of water stress on down-the-drain chemical exposure and potential risk. Incorporating spatial and temporal variation in water stress and its impact to the risk of chemicals in the environment, through the lens of future scenarios, provides a new dimension in the development of consumer products. Incorporating these issues into product development, now, will ensure that both consumers and the environment will be appropriately stewarded, especially considering future environmental challenges.

Wednesday, November 16th, 10AM - 12:40PM, Session 5.18.T-08; Convention Center –304/305 

Title:  SolBeePop: Assessing Risks of Pesticide Exposures to Populations of Solitary Bees in Agricultural Landscapes, a Modeling Approach. Authors: Amelie Schmolke, Waterborne Environmental, Inc., Nika Galic, Syngenta Crop Protection, Vanessa Roeben, Bayer Crop Science, Thomas G. Preuss, Bayer Crop Science, Mark Miles, Bayer Crop Science, Silvia Hinarejos, Sumitomo Chemical.

Abstract: Solitary bees, including both wild and managed populations, are important pollinators of crops and wild flower communites. Solitary bees can potentially be exposed to pesticides via multiple routes of exposure which may differ between species and between solitary bees and the Western honey bee (Apis mellifera) which is currently used as surrogate for risk assessments across bee species. Species-specific traits may additionally interact with the potential for exposures and effects, including, for instance, phenology, reproductive rates and flower preferences. We are presenting a population model for solitary bees in agricultural landscapes, SolBeePop. The model was developed to simulate a variety of species by using species-specific ecological traits as model parameterizations. Model parameterizations for several species (Osmia bicornis, O. cornifrons, O. cornuta, O. lignaria, Megachile rotundata, Nomia melanderi, and Eucera (Peponapis) pruinosa) were compiled from the literature whereby data availability varied by species. The model can simulate the diverse life cycles of the species and can be used to explore the importance of uncertainties in data to the population dynamics. Exposures to a pesticide through multiple exposure routes can be considered, such as nectar, pollen, and nesting materials. Effects are implemented using a simplified toxicokinetic-toxicodynamic model, BeeGUTS, adapted specifically for adult bees while an exposure-response functions is applied to simulate effects to developing in-nest life stages. We calibrated and validated the model with control data from semi-field studies conducted with O. bicornis. We applied the model across the model species to assess the impacts of different trait combinations on population dynamics, exposures and population-level effects in relevant landscape scenarios. The model provides a valuable tool for higher-tier pesticide risk assessments across species of solitary bees in agricultural landscapes.

Wednesday, November 16th, 10AM - 12:40PM, Session 5.11.T-03; Convention Center –Ballroom B 

Title: Modeling pesticide effects on multiple threatened and endangered Cyprinid fish species to support decision making. Authors: Chiara Accolla, Waterborne Environmental, Inc., Amelie Schmolke, Waterborne Environmental, Inc., Andy Jacobson, Waterborne Environmental, Inc., Colleen Roy, Waterborne Environmental, Inc., Valery E. Forbes, University of Minnesota, Richard Brain, Syngenta Crop Protection, Nika Galic, Syngenta Crop Protection.

Abstract: Mechanistic models are invaluable in ecological risk assessment (ERA) because they facilitate extrapolation of organism-level effects to population-level effects while accounting for species life history, ecology, and vulnerability. Therefore, models are particularly useful for assessing potential risks of pesticides to threatened and endangered species, for which data collection and laboratory tests are challenging or impossible. We developed a model framework to compare the potential effects of the fungicide chlorothalonil across several listed species of cyprinid fish and explored species-specific traits of importance at the population level.  The model is an agent-based model based on the dynamic energy budget (DEB) theory. As a case study, we considered four listed species of Cyprinidae: Humpback chub (Gila cypha), Spikedace (Meda fulgida), Topeka shiner (Notropis topeka), and Devils River minnow (Dionda diaboli). Potential direct lethal and/or sublethal effects on individual fish were considered as well as indirect effects through reduction in prey. We calibrated four effect sub-models to account for different effect pathways based on experimental data from exposure to chlorothalonil. Toxicokinetic-toxicodynamic models were used for representing direct effects, whereas indirect effects were described by decreasing food availability. Exposure profiles were constructed based on a degradate (hydroxychlorothalonil), given the relatively short half-life of the parent chlorothalonil.  We performed two kinds of simulations (i) we applied all effect sub-models simultaneously and considered different exposure magnification factors (EMFs); (ii) we sequentially added the different effect sub-models to test their relative importance. We demonstrated that exposure affected population dynamics depending on species-specific life-history traits and processes (i.e., density dependence). Different EMFs were required to achieve a comparable population decrease across species. Moreover, sequentially adding effect sub-models resulted in different outcomes depending on the interplay of life-history traits and density-dependent compensation effects. We conclude by stressing the importance of using models in ERA to account for species-specific characteristics and ecology, especially when dealing with listed species and in accordance with the necessity of reducing animal testing.

Waterborne Posters

Title: Mechanistic effect models: A brief history to highlight benefits and obstacles in using them for chemical risk assessment. Authors: Chiara Accolla, Waterborne Environmental, Inc., Valery E. Forbes, University of Minnesota, Nika Galic, Syngenta Crop Protection, Sandy Raimondo, US Environmental Protection Agency, Amelie Schmolke, Waterborne Environmental, Inc., Maxime Vaugeois, Syngenta Crop Protection.

Abstract: Although mechanistic effect models are widely recognized as potentially valuable tools, they are still not regularly used or accepted for regulatory Ecological Risk Assessments (ERA). There are several possible reasons for this, including the lack of trust and transparency in the modeling process, but more importantly the mismatch between the endpoints they yield and those that have been traditionally applied and the lack of “bright lines”.

This presentation aims to open a thorough discussion among all the parties involved in the risk assessment process to understand how we could enhance the use of mechanistic effect models in different regulatory contexts. To this end, we present a brief history of mechanistic effect models for ERA and give an overview of their goals within the ERA context. We show some examples of effect models developed within different stakeholders (US EPA, academia, business) and highlight their similarities and differences. 

In this context, we suggest focusing on a few important points:

  • Define standardized outputs of interest, such as population abundance, population decline, recovery, or extinction probability and how these outputs can be applied in decision making.
  • Determine which and how environmental scenarios  should be applied across models.
  • Find agreement on those model features deemed essential to represent populations such that risks can be adequately assessed.
  • Underline the importance of identifying model use and objectives before model development and ensure transparency and consistency in the overall process. 

We also tackle some common issues linked to model acceptance and conceptual misunderstandings. For example, models are currently often newly developed or adapted for the context of a specific risk assessment and thus, include different processes relevant to the system and objectives. This reduces consistency across models and increases the effort involved in reviewing them.  Moreover, there are different points of view regarding how to best use data obtained from surrogate species, how to deal with data gaps, and how to address model uncertainty. In conclusion, we hope to foster dialog among stakeholders to ensure the use of the best available science in a standardized way to support ecological risk assessments of chemicals.

Title: Analysis of the Fate and Transport of SARS-CoV-2 in Wastewater and Surface Waters in the US Using iSTREEM®, Authors: Raghu Vamshi, Waterborne Environmental, Inc., Brenna Kent, Waterborne Environmental, Inc.

Session title: 4.14 – Innovative Analytical Approaches for Understanding Environmental Contaminants of Emerging Concern

Abstract:  The ongoing pandemic of coronavirus disease 2019 (COVID‑19) caused by severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) is taking a huge toll on humankind.  Infected people excrete the virus through their feces which is conveyed to wastewater treatment plants (WWTP) where its genetic material, RNA, can be detected.  SARS‑CoV‑2 may remain active while being transported in water through the WWTP and into receiving waters.  Therefore, it is critical to determine the distance the virus may travel and whether surface water, including drinking water, is at risk.  Modeling the fate of viruses in WWTPs and surface water on a national level could be an additional evaluation of monitoring efforts.   iSTREEM®, a tool used for modeling the fate and transport of down-the-drain materials, was used to estimate viral concentrations in effluent at WWTPs and surface water for the continental U.S.  Inputs for modeling included the viral load, removal in WWTPs, and in-river decay which were based on monitoring data, current literature, and expert opinions.  This analysis indicated that WWTPs are highly efficient in removing SARS‑CoV‑2.  Residual RNA fragments were either removed or diluted in the surface waters and were not measured above current detection limits.  Treatment of drinking water will result in even greater loss of viral fragments, if present, indicating that SARS‑CoV‑2 most likely does not pose a health risk in the U.S. via drinking water.  This is the first study to provide quantitative data at a national scale to support these claims.

Title: Evaluating Subsurface Movement of PFAS Compounds Using Both One and Multi-Dimensional Modeling Approaches, Authors: Colleen Roy, Waterborne Environmental, Inc., Brenna Kent, Waterborne Environmental, Inc., Gerco Hoogeweg, Waterborne Environmental, Inc., Amy Ritter, Waterborne Environmental, Inc., Raghu Vamshi, Waterborne Environmental, Inc.

Session title: 4.14 – Innovative Analytical Approaches for Understanding Environmental Contaminants of Emerging Concern

Abstract:  Per- and polyfluoroalkyl substances (PFAS) are used in in numerous consumer products and industrial applications. Not only are PFAS widely used, but they also cover a vast chemical group with thousands of distinct compounds. Because of this, they have become a ubiquitous occurrence in the environment. Several small and large-scale monitoring programs have shown widespread presence of these compounds in air, surface and ground water, and soil media. As awareness of these chemicals continues to increase, concerns due to their persistence and toxicity to environmental and human health also grows. Through their PFAS Strategic Roadmap, USEPA has been prioritizing ongoing work to better understand and eventually reduce the potential exposure and risks caused by these chemicals. USEPA has also included 29 PFAS to be monitored under the fifth Unregulated Contaminant Monitory Rule (UCMR 5) between 2023 and 2025. In addition to monitoring data, reliable modeling tools to evaluate the fate and transport of these chemicals are critical to the development of risk assessment and remediation strategies. To date, limited work has been done to better understand the fate and transport of these complex chemicals in the environment using existing modeling approaches. Rising public interest and increasing regulatory action has made the need for modeling an important next step in advancing the understanding of these persistent chemicals. This work will focus on applying standard modeling approaches to understand the fate and transport of PFAS. Two models, HYDRUS and GeoPEARL, were used to simulate PFAS measured at contaminated sites. Previously, these models were applied to simulate PFOA and PFOS in groundwater at an airport which had been used as firefighter training site, exposing the area to AFFF. This work has been expanded to include sites with other potential PFAS sources such as landfills. Results from modeling were compared with available groundwater monitoring data for these sites. The practical utility of the standard modeling approaches for application to address the PFAS challenges over small and large geographies are discussed.

Title: Right-Sizing UV Filter Exposure Estimates – A Critical Need. Authors: Nikki Maples-Reynolds, Waterborne Environmental, Inc., Scott Dyer, Waterborne Environmental, Inc and LeTourneau University, Brenna Kent, Waterborne Environmental, Inc., Colleen Roy, Waterborne Environmental, Inc., Raghu Vamshi, Waterborne Environmental, Inc., W. Martin Williams, Waterborne Environmental, Inc., Todd Gouin, TG Environmental Research, Nicola Hefner, DSM, Eva Klingelmann, Symrise, Sascha Pawlowski, BASF, Amelie Ott, Cosmetics Europe.

Session title: 2.06 – Detection, toxicity and environmental risk of UV filters in aquatic ecosystems

Abstract:  Per- and polyfluoroalkyl substances (PFAS) are used in in numerous consumer products and industrial applications. Not only are PFAS widely used, but they also cover a vast chemical group with thousands of distinct compounds. Because of this, they have become a ubiquitous occurrence in the environment. Several small and large-scale monitoring programs have shown widespread presence of these compounds in air, surface and ground water, and soil media. As awareness of these chemicals continues to increase, concerns due to their persistence and toxicity to environmental and human health also grows. Through their PFAS Strategic Roadmap, USEPA has been prioritizing ongoing work to better understand and eventually reduce the potential exposure and risks caused by these chemicals. USEPA has also included 29 PFAS to be monitored under the fifth Unregulated Contaminant Monitory Rule (UCMR 5) between 2023 and 2025. In addition to monitoring data, reliable modeling tools to evaluate the fate and transport of these chemicals are critical to the development of risk assessment and remediation strategies. To date, limited work has been done to better understand the fate and transport of these complex chemicals in the environment using existing modeling approaches. Rising public interest and increasing regulatory action has made the need for modeling an important next step in advancing the understanding of these persistent chemicals. This work will focus on applying standard modeling approaches to understand the fate and transport of PFAS. Two models, HYDRUS and GeoPEARL, were used to simulate PFAS measured at contaminated sites. Previously, these models were applied to simulate PFOA and PFOS in groundwater at an airport which had been used as firefighter training site, exposing the area to AFFF. This work has been expanded to include sites with other potential PFAS sources such as landfills. Results from modeling were compared with available groundwater monitoring data for these sites. The practical utility of the standard modeling approaches for application to address the PFAS challenges over small and large geographies are discussed.

Title: A New Software Tool for Promoting Standardization of Conceptual Diagrams for Mechanistic Effect Models. Authors: Kristin Crouse, University of Minnesota; Valery Forbes, University of Minnesota; Chiara Accolla, Waterborne Environmental, Inc.; Thomas Banitz, Helmholtz Centre for Environmental Research - UFZ, Germany; Nika Galic, Syngenta Crop Protection, Switzerland; Volker Grimm, Helmholtz Centre for Environmental Research - UFZ, Germany;  Sandy Raimondo, Office of Research and Development (ORD), U.S. Environmental Protection Agency; Amelie Schmolke, Waterborne Environmental, Inc.; and Maxime Vaugeois, Syngenta Crop Protection.

Session title: 5.03 – Benefits and Obstacles in Using Mechanistic Effect Models for Chemical Risk Assessments

Abstract: Due to lack of guidance, risk assessors and risk managers have shown reluctance to use mechanistic effect models for ecological risk assessment. Recent efforts have promoted guidance in documentation (e.g., ODD, TRACE), evaluation (e.g., TRACE, Pattern-Oriented Modeling) and development (e.g., Pop-GUIDE). However, guidance is still needed for how to build conceptual model diagrams, which visually communicate the salient details of a model to a general audience. Currently, modelers create conceptual model diagrams using a wide variety of approaches, such that two modelers depicting the same model would likely yield vastly different diagrams. To reduce individual bias in diagram construction, we propose a new software tool that produces standardized and consistent diagrams for any kind of mechanistic effect model. Users will visit a public webpage and answer a series of questions about their model. The software will generate a visual diagram from these responses, which the user can download for free. The diagram will include information on key elements of a mechanistic effect model, including: (1) properties of the environment such as spatial heterogeneity, external drivers, or chemical exposure; (2) organism characteristics such as life-history traits, behavior, and energetics; (3) other key features such as density dependence and stochasticity; and (4) important model outputs such as abundance, biomass, and more. In the generated diagram, these elements are both listed as text and depicted visually to show their connections, thus highlighting the main features of the model while being consistent across models. We expect that our standardized diagrams will be quick and simple to understand, capturing the key features of the model without going into too much detail, and be applicable to a wide range of model types and complexities. Ultimately, these improvements will promote transparency in model descriptions and will cultivate trust among modelers, assessors and managers.