PresentationsHome and Personal Care Products2018
Estimating environmental emissions and aquatic fate of sludge-bound CECs using spatial modeling and US datasets
In the US, 50% of the sludge produced during wastewater treatment is recycled to land (www.epa.gov/biosolids). Some chemicals in consumer products may be highly removed during the wastewater treatment process due to sorption and binding to organic matter, ending up in sludge solids where it has the potential to be applied to land surfaces, subject to erosion or runoff processes potentially entering nearby surface waters. However, biosolids mass applied to land is not evenly distributed across the US landscape due to variable population density, local sludge management practices, and availability of land application sites. We have developed a proof-of-concept model to aide in the prospective assessment of CECs contained in WWTP sludge applied to land. This spatially-explicit, national model is based on publicly available datasets, combined with a spatial-hydrologic framework containing geographically variable emissions linked to a river network allowing for environmental transport via surface water. The hydrologic framework is based on a set of basins and rivers (www.hydrosheds.org) linked to emission characteristics for over 77,000 sub-basins. Emission characteristics are derived from facility data in the USEPA Clean Watersheds Needs Survey (www.epa.gov/cwns) to estimate consumer product usage linked to wastewater treatment, and spatially-variable data on biosolid applications. The USDA Cropland Data Layer (www.nass.usda.gov) provides potential land application sites, from which proximity to surface water plays a role in the potential for CECs to transport from land to freshwater (using a meta-model estimated from pesticide assessment models). Concentrations of CECs are routed through the river network based on local river attributes (e.g., flow) combined with assumptions about chemical fate in the aquatic environment. Results of various simulations show the spatial patterns of biosolids applications, potential to enter surface water, and estimated freshwater concentrations of an ingredient in a hypothetical consumer product. Implications of altering model assumptions are discussed. While the presented material is a simulated example of the environmental emission and fate of a consumer product ingredient, it represents a viable approach to assessing whether this pathway via land applied biosolids may be of concern for consumer product chemicals, and ultimately helping to inform environmental policy on this subject.
Christopher Holmes, Joshua Amos, Amy Ritter, and Marty Williams (Waterborne Environmental). Estimating environmental emissions and aquatic fate of sludge-bound CECs using spatial modeling and US datasets. Platform SETAC 2018. Sacramento, CA.
Exposure and effects of clothianidin residues in corn pollen: Honey bee colony simulation in a field setting
As managed pollinator species, honey bees provide major pollination services to a wide variety of crops across the globe. At the same time, they are potentially vulnerable to the effects of systemic neonicotinoids because residues can occur in pollen and nectar collected by the bees. However, the assessment of potential effects of neonicotinoids on colonies in field studies is challenging because multiple environmental conditions interact with the colonies’ health. Honey bee colony models such as BEEHAVE provide the opportunity to assess potential influx of residues into a colony via different routes, and their effects on bees in the hive can be dependent on their stage-dependent consumption rates and sensitivities. We extended BEEHAVE to represent exposure to clothianidin via residues in pollen from treated corn fields. Landscapes around the colonies were simulated using land cover data from sites across the Midwest of the United States. Simulated foragers collect pollen from flower resources across the landscape including corn pollen during the corn blooming period. Clothianidin residues are consumed by larvae and worker bees. Different residue levels in corn pollen were applied to assess impacts on honey bee colonies over a one-year cycle. Clothianidin effects on colony strength were only observed if unrealistically high residue levels in the pollen were simulated. The landscape composition significantly impacted the collection of pollen (residue exposure) from the corn fields, resulting in higher colony-level effects in landscapes with low proportions of semi-natural land. The case study with the mechanistic honey bee colony model presents a path to the application of such models in the context of pesticide risk assessment.
Amelie Schmolke (Waterborne Environmental), Farah Abi-Akar (Waterborne Environmental), Silvia Hinarejos (Sumitomo). Exposure and effects of clothianidin residues in corn pollen: Honey bee colony simulation in a field setting. Platform SETAC 2018. Sacramento, CA.
Applying a mechanistic honey bee colony model to assess multiple factors impacting colony overwintering survival
Honey bee colony feeding studies are one type of Tier II semi-field studies designed to determine potential effects of pesticides on free-foraging whole colonies during and after dietary intake of a known pesticide concentration. These studies represent a progressively more realistic level of refinement for pollinator studies compared to individual laboratory-based studies since they are intended to reflect a worst-case exposure scenario in the field. Colony feeding studies are designed to test toxicity over a foraging season and following overwintering period. However, such studies are very cost- and time-intensive to conduct, and high overwintering losses of control hives have been observed in some studies. Loss of control colonies indicates that stressors other than pesticides, e.g. resource availability, weather, diseases and beekeeping activities, likely influence colony overwintering survival, confounding the assessment of impacts caused by pesticides. Honey bee colony models have been gaining interest as tools in pesticide risk assessment to inform study design and ultimately, colony-level risks to honey bees. In the current study commissioned by the Pollinator Research Task Force, we apply the honey bee colony model BEEHAVE to simulate colony dynamics observed in negative control colonies from multiple colony feeding studies. Detailed landscape-level data inform the resource availability for the simulated foragers in the model. In addition, weather data, initial colony condition and feeding patterns were analyzed across studies and translated to model inputs. In a calibration step, we adjusted parameters in BEEHAVE to achieve simulated dynamics corresponding to colony conditions reported in the studies. Study data collected in summer and fall were analyzed for predictors of overwintering success of individual colonies. BEEHAVE simulations with different combinations of external factors were used to assess their importance for colony condition. Colony conditions at study initialization and feeding patterns both influenced the colony condition in the fall, and thus, the probability of overwintering survival. Model simulations can be used to estimate colony-level outcomes under conditions deviating from those in the studies to inform study design and extend the use of the available data. Pesticide effects can be included in future model analyses, and analyzed in the context of multiple factors that impact colony health and overwintering success.
Amelie Schmolke (Waterborne Environmental), Farah Abi-Akar (Waterborne Environmental), Nika Galic (Syngenta), Silvia Hinarejos (Sumitomo). Applying a mechanistic honey bee colony model to assess multiple factors impacting colony overwintering survival. Platform SETAC 2018. Sacramento, CA.
Combining an individual-based model and an aquatic food web-ecosystem model to assess ecological risks: A case study with the endangered Topeka shiner
The Comprehensive Aquatic System Model (CASM) is a process-based integrated bioenergetics and habitat quality model that simulates population, community, and ecosystem-level effects of chemical stressors based on an aggregated population structure defined by an average-sized individual. An individual-based bioenergetics and population model (IBM) was developed for the endangered Topeka shiner (Notropis topeka) to incorporate detailed life-history and age-specific and size-specific attributes of population dynamics not represented in the CASM. The models were executed in tandem with daily IBM population growth dynamics transferred to CASM, which in turn computed the corresponding daily modifications to the food web. The CASM food web results were transferred back to the IBM in the form of adjusted Topeka shiner prey biomass values. This uniquely integrated model combination was implemented to simulate potential ecological risks for Topeka shiner in a generalized Iowa headwater pool, representative of known Midwestern habitat and range for this species. Ecological risks were computed using time-integrated differences between the population biomass values of 365-day baseline and exposure simulations. Risks were estimated for example daily pesticide exposures of varying magnitude, timing, and duration. Potential direct toxic effects to Topeka shiners were modelled within the IBM. The resulting modelled impacts on population biomass were used by the CASM to compute corresponding food web-ecosystem effects. The IBM provided the capability to examine the potential population-level risks based on detailed sensitivities of early life stages and adults to pesticide exposures. The CASM extended the IBM assessment capability by extrapolating potential direct effects on Topeka shiners to associated indirect changes in headwater pool community structure and ecosystem function. The presentation highlights the advantages afforded by the integrated IBM-CASM modeling approach to ecological risk assessment.
Steven Bartell (Cardno), Amelie Schmolke (Waterborne Environmental), Colleen Roy (Waterborne Environmental), Nicholas Ralston (University of North Dakota), Daniel Perkins (Waterborne Environmental), Nika Galic (Syngenta), Richard Brain (Syngenta). Combining an individual-based model and an aquatic food web-ecosystem model to assess ecological risks: A case study with the endangered Topeka shiner. Platform SETAC 2018. Sacramento, CA.
A US, field-scale, herbicide spray drift deposition and biological evaluation study: Methods and implications for risk assessment
Spray drift from pesticide applications is considered as a potential route of exposure in environmental risk assessment. Typically, spray drift deposition is modeled using terrestrial plant effects endpoint derived from worst-case, full rate direct spray studies, and combined in the risk assessment framework to represent extreme worst-case risk to non-target organisms. The objective of this work was to merge observed plant effects with spray drift exposure in a single study. A 40-acre field-scale, spray drift study was developed to simultaneously measure spray drift deposition, airborne interception, and potential biological effects of an herbicide under conservative drift conditions and a relatively low-drift nozzle. This study was conducted in four replications, each with a two-swath spray pattern (90 ft per swath) upwind of a deposition zone (perpendicular to wind direction), generally following the generic U.S. Environmental Protection Agency verification protocol, Testing Pesticide Application Spray Drift Reduction Technologies for Row and Field Crops. Within each replicate application, an array of three perpendicular sampling lines were used to measure drift deposition out to 400 ft, airborne interception out to 75 ft, and potential direct plant effects at set distances (5, 15, 25, 23, and 45 ft) from the edge of the downwind spray application . At each distance and sampling line, further replication of spray drift deposition, airborne interception, and biological effects were assessed in replicated fashion in a nested, replicated design. The timing of the herbicide application for each of the four replications targeted steady wind speeds between 8 to 12 mph. Wind direction was measured within a 30-degree angle of the downwind field orientation to ensure that spray drift would travel toward the collection area and across the furthest sampling points. Results from this study design refine effects determined in laboratory studies under worst-case exposure scenarios (i.e. direct over the top application) by addressing how terrestrial non-target plants actually experience exposure under natural conditions in the field, which can better inform risk assessment and risk management decisions.
Daniel Perkins (Waterborne Environmental), Greg Goodwin (Waterborne Environmental), Greg Kruger (University of Nebraska-Lincoln), Abby Lynn (All Aspects Consulting), Farah Abi-Akar (Waterborne Environmental), Richard Brain (Syngenta). A US, field-scale, herbicide spray drift deposition and biological evaluation study: Methods and implications for risk assessment. Platform SETAC 2018. Sacramento, CA.
Influence of particle size on prospectively modeled environmental concentrations of microplastics in the Sandusky River watershed
The presence of nano- and microplastics (MPs; particles < 5 mm) in the aquatic environment is a topic of increasing discussion and research. Although measurement and monitoring data are indispensable, there is a need to prospectively estimate concentrations to enable forward-looking assessments and to guide analysis of retrospective ecological analyses. For traditional chemicals, fate and exposure models have been proven to be very helpful and are widely used. However, to date few models exist that simulate the transport and fate of MPs in freshwater systems. This presentation presents simulations of the transport and fate of various-sized MPs emitted from wastewater treatment plants into freshwater riverine systems, and tracks concentrations moving downstream from headwater into Lake Erie. We linked the NanoDUFLOW model (a detailed MP aggregation-sedimentation model integrated in a hydrological and particle transport model) with iSTREEM® (developed to estimate chemical concentration distributions for all rivers receiving WWTP discharges in the US) for a range of particle sizes. This combines the mechanistic realism of NanoDUFLOW, accounting for formation and settling of heteroaggregates, with the US well-established iSTREEM implementation. Depth dependent in-stream first order removal rate constants simulated with NanoDUFLOW were combined with standard iSTREEM output which simulated the emission, transport and water column concentrations of different MP sizes. We modeled floating as well as non-buoyant MP, for sizes ranging from 100 nm to 1000 µm. We also modeled a combined mixture of particle sizes based on effluent measurements from Mason et al (2016). Simulations were spatially explicit with MP concentrations being modeled for the Sandusky River watershed in Ohio containing over 300 miles of river downstream of 20 WWTPs. Modelling results show the effects of population density, MP size and environmental conditions on riverine concentrations and export to Lake Erie. Buoyant as well as the smallest non-buoyant MP fractions can be transported over long distances, reaching receiving waters such as the Great Lakes. In contrast, larger non-buoyant MPs settle more locally in the vicinity of the WWTPs.
Christopher Holmes (Waterborne Environmental), Albert Koelmans (Wageningen University), Scott Dyer (Waterborne Environmental). Influence of particle size on prospectively modeled environmental concentrations of microplastics in the Sandusky River watershed. Poster SETAC 2018. Sacramento, CA.
Adequacy and uncertainty in models and scenarios developed to estimate pesticide wash-off and runoff in residential settings
A variety of pesticide products, including Insecticides, herbicides, and fungicides, are used by homeowners and licensed Pest Control Operatiors to eradicate or deter pests on lawns and ornamentals, vegetable gardens, homes, and other structures. Pesticide detections in urban streams have resulted in an increase in research over the past decade to understand the potential for pesticide washoff to occur from various pervious and impervious application sites. Regulatory agencies, chemical registrants, and other researchers have employed a variety of approaches to model pesticide runoff associated with residential uses. This presentation compares the underlying prinicipals in several models and scenarios that have been adopted or proposed for pesticide registration review and risk assessment by regulatory agencies in the U.S. and the E.U.; and evaluates their appropriateness for risk assessment for various categories of outdoor residential-use pesticide products. The models/scenarios include the Home and Garden scenario developed for the HardSPEC model by the Food and Environment Research Agency in the U.K., residential scenarios developed for PRZM5 by the U.S. Environmental Protection Agency, and adapting urban stormwater management models including the Stormwater Management Model (SWMM5) and the P8 Urban Catchment Model.
Marty Williams (Waterborne Environmental), Yuzhou Luo (CDPR), and Michael Winchell (Stone Environmental). Adequacy and uncertainty in models and scenarios developed to estimate pesticide wash-off and runoff in residential settings. Platform SETAC 2018. Sacramento, CA.
Setting a species-specific population model in the context of an aquatic food web model: A case example for the Topeka shiner
For species listed as threatened or endangered under the Endangered Species Act (ESA), higher-tier environmental risk assessments (ERAs) include assessing potential overlap of pesticide use patterns and the species’ geographical range. However, potential risks to populations also depend on temporal aspects of exposure and effects as well as interactions with ecosystem-mediated effects. We developed an individual-based population model (IBM) for the Topeka shiner (Notropis topeka), a fish species listed as endangered, and linked it with an aquatic food web model (comprehensive aquatic systems model, CASM). The CASM was parameterized and calibrated to represent the waterbody conditions and aquatic species community in a small headwater pool in Iowa, representative of a Topeka shiner’s key habitat within its geographical range. In the IBM, Topeka shiners feed on several groups in the aquatic food web according to published diet studies. Fish are simulated to grow according to a bioenergetics submodel that considers consumption, respiration and waste losses. We modelled the effects of alterations of the food web on the Topeka shiner populations by systematically reducing the available biomass of groups that the shiners consume. These alterations are generic simulations of the potential effects of pesticide exposures in agricultural landscapes around the shiner’s habitat. Potential pesticide effects on the food web depend on the compound, magnitude, timing and duration of exposure, and are simulated in the model by applying daily concentrations of a pesticide in the simulated waterbody which can be derived from field measurements or fate models. The linked models provide a platform for the assessment of potential direct and food-web mediated indirect effects of stressors such as pesticides on species populations.
Amelie Schmolke (Waterborne Environmental), Steven Bartell (Cardno), Colleen Roy (Waterborne Environmental), Nicholas Green (Waterborne Environmental), Daniel Perkins (Waterborne Environmental), Nika Galic (Syngenta), Richard Brain (Syngenta). Setting a species-specific population model in the context of an aquatic food web model: A case example for the Topeka shiner. Platform SETAC 2018. Sacramento, CA.
Taxa-focused approach to standardizing use of population models in ecological risk assessment
In spite of widespread acceptance of the utility of population modeling and advocacy of these approaches for more ecologically relevant perspective, they are not routinely incorporated in ecological risk assessments (ERA). A systematic framework for situation-specific model development is one of the major challenges to broadly adopting population models in ERA. As risk assessors confront the multitude of species and chemicals requiring evaluation, adaptable model templates and taxa-specific guidance on model parameterization would facilitate this process. We build on previous work that created a framework and decision guide for developing population models for ERA by focusing on anuran amphibians. Anurans have a unique life cycle with varying habitat requirements and physiological processes. These species belong to the amphibian class, which is facing global population declines, due in large part to anthropogenic stressors, including pesticide effects. A stage-based matrix model broadly represents the anuran life cycle. We synthesize information from databases and literature relevant to amphibian risks. At the individual, population, and ecological levels we identify traits that influence inherent sensitivity, population vulnerability, and environmental constraints. We also outline methods of modifying a basic population model to suit specific risk assessment needs with appropriate scale and parameterization to evaluate pesticide effects. A standardized population model approach for anuran ERA offers an example method of identifying potential risks and determining long-term impacts of chemical stressors to populations across taxonomic groups.
Jill Awkerman (USEPA), Sandy Raimondo (USEPA), Amelie Schmolke (Waterborne Environmental), Katherine Kapo (Waterborne Environmental), Nika Galic (Syngenta), and Valery Forbes (University of Minnesota). Taxa-focused approach to standardizing use of population models in ecological risk assessment. Platform SETAC 2018. Sacramento, CA.
Watershed modeling: Comparison of process-based model PRZM/SWAT with regression-based model SEAWAVE-QEX
Water quality monitoring data, specifically for pesticides, can represent best-available exposure profiles relevant to ecological risk assessment; however, there are challenges in synthesizing these data toward making conclusions about the nature of the potential range of risk. Some of these challenges include: data collection frequency, monitoring period duration, interpreting exposure profiles from one location to another, and monitoring system scale. To address these challenges, statistical approaches may be applied to characterize empirical trends. Additionally, process-based numerical modeling approaches can offer a different perspective on synthesis and interpretation of monitoring data. A comparison of a statistical and process-based numerical model was conducted to evaluate strengths and weaknesses of representing, synthesizing, and conclusions from monitoring data. This comparison was developed from pesticide measurements of six intensively-monitored HUC12 headwater watersheds in the Midwest. SEAWAVE-QEX is a regression model that incorporates a linear trend term, covariates accounting for seasonality, and a transformation of flow to represent a long-term pesticide trend at a specific monitoring location. PRZM/SWAT (Pesticide Root Zone Model/Soil Water Assessment Tool) is a spatially-distributed hydrologic and chemical transport numerical model that combines upland chemical and hydrologic processes from PRZM and stream flow and chemical transport processes from SWAT. The predictive quality and limitations of these two models (SEAWAVE-QEX and PRZM/SWAT) was assessed against observed, daily concentration measurements as well as hypothetical data collection frequency and timing (derived from sub-sampling the same data sets).
Wenlin Chen (Syngenta), Daniel Perkins (Waterborne Environmental), Andrew Jacobson (Waterborne Environmental), Colleen Roy (Waterborne Environmental), and Farah Abi-Akar (Waterborne Environmental). Watershed modeling: Comparison of process-based model PRZM/SWAT with regression-based model SEAWAVE-QEX. Platform SETAC 2018. Sacramento, CA.