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Publications: Water/Wastewater Assessments

PostersWater/Wastewater Assessments2019

Modeling aquatic and terrestrial transport pathways for microplastics entering WWTP systems

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SETAC 2019, TP144
Toronto, Ontario, Canada
Session Title: Microplastics in the Environment: Transport, Fate and Ecological Effects
Tuesday, November 5, 2019
8:00 am, Exhibit Hall

Abstract:
Microplastics may enter the environment from a number of sources and in many forms. Plastic particles may be present as influent into municipal wastewater treatment plants (WWTPs). A large portion of these are removed from the water phase during the treatment process, and generally end up in the solids (i.e., sludge). Sludge disposal varies by country, region and locality, including landfill, incinerator, compost, or as land-applied biosolids. There is potential for particles in biosolid applications to reach aquatic systems depending on application location and subsequent environmental conditions. We present a broad-scale model designed to estimate emissions and model the fate of plastic particles exiting WWTPs into the terrestrial and aquatic environments, using spatially-explicit information on WWTPs, river hydrology and terrestrial transport potential. This regional/continental scale model is based on publicly available datasets and contained in a modular and transparent framework which is scalable and portable to multiple geographies. This presentation will demonstrate the utility of the model as applied to different regions, and how the resulting information about ultimate mass disposition within the environment (e.g., soil, freshwater, sediment, marine) and surface water concentrations can be examined to help inform the discussion about prospectively assessing the presence and concentration of microplastic particles in the environment as emitted by WWTPs.

C. Holmes (Applied Analysis Solutions), J. Amos (Waterborne), S. Dyer (Waterborne). Modeling aquatic and terrestrial transport pathways for microplastics entering WWTP systems. Poster, SETAC 2019. TP144. Toronto, Ontario, Canada.

PresentationsHome and Personal Care Products, Water/Wastewater Assessments2019

Development of integrated risk assessment framework and methodology for assessing environmental safety of chemicals disposed down the drain in China

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SETAC 2019, Platform 30
Toronto, Ontario, Canada
Session Title: Building Bridges Between Lab-and Field-Derived Data: Methods for the Assessment of Complex Environmental Issues
Monday, November 4, 2019
10:40 am, Room 717B

Abstract:
The new Chinese regulatory chemical management scheme calls for increased development of risk-based assessment framework and tools that can address regional and national needs. Important considerations include identifying chemicals with high potential for adverse impact to humans and the environment early in the assessment, while also recognizing regional differences in the levels of economic and infrastructure development as well as environmental conditions. An integrated, tiered environmental risk assessment framework and methodology was developed for assessing the environmental safety of chemicals disposed down the drain in China. The tiers incorporate China’s specific exposure conditions as well as consideration of Chinese native species for effects assessment. The framework starts with a Low Tier utilizing the existing Chinese regulatory qualitative method, whereas Mid-Tier is quantitative using deterministic and probabilistic approaches that account for per capita residential water usage, wastewater treatment capability, as well as wastewater/in-stream dilution factors. A High Tier spatially explicit aquatic exposure model was recently created which leveraged historic work on the iSTREEM® model (American Cleaning Institute). A high-resolution river flow dataset was established based on the Curve Number method (Natural Resources Conservation Service, U.S. Department of Agriculture) and further validated by monitoring data. Case studies will be presented for consumer product ingredients which indicate Lower Tiers are conservative with greater environmental realism associated with High Tier methodology. A key aspect for the integrated framework is environmental effects assessment based on Chinese native species, as chemical registrations in China routinely involve local fish testing. The Chinese Rare Minnow (Gobiocypris rarus) and Chinese Medaka (Oryzias sinensis) are examples of leading local species. This research developed an understanding of the ecology, physiology, and other biological information allowed for the extrapolation between these two species and other OECD standard test species (e.g., zebrafish). We investigated comparative fish acute toxicity using 3,4-Dichloroaniline and NaCl with studies planned on additional chemicals and species. Chinese native species data will be utilized not only for direct hazard assessment but also for the development of statistical extrapolation methods, such as interspecies correlation estimation (ICE) models. ICE models use available toxicity data of surrogate species to predict untested species to expand the domains of ecotoxicological information for China’s integrated environmental risk assessments.

M. Fan (P&G), K. McDonough (P&G), S. Belanger (P&G), Z. Liu (Chinese Research Academy of Environmental Sciences), R. Vamshi (Waterborne), S. Csiszar (P&G), J. Menzies (P&G), X. Wang (Chinese Research Academy of Environmental Sciences), K. Kapo (Waterborne).  Development of integrated risk assessment framework and methodology for assessing environmental safety of chemicals disposed down the drain in China. Platform 30, SETAC 2019. Toronto, Ontario, Canada.

PresentationsWater/Wastewater Assessments2019

High-Resolution Global Mean-Annual Surface Runoff And River Flow Datasets For Use In Risk Assessments

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SETAC 2019, Platform 50
Toronto, Ontario, Canada
Session Title: Challenges in Characterizing Exposures to Organic Chemicals: Multiple Sources, Multiple Pathways and Multiple Scales
Monday, November 4, 2019
8:40 am, Room 716B

Abstract:
The availability of detailed surface runoff and river flow data across large geographic areas is crucial for modeling in ecological risk assessments; a few countries (e.g., U.S.) offer such data at a high-resolution and most countries do not. Lack of detailed spatial data and challenges with intense processing have been the limiting factors in developing high-resolution river flows over large spatial scales. iSTREEM®, a broad-scale spatial model in the U.S. incorporates a detailed hydrology network with river flows from the NHDPlus to estimate exposure across large areas from the use of down-the-drain chemicals. It combines WWTP emissions into corresponding flow at receiving rivers to estimate dilution factors and down-the-drain chemical concentrations, and route them through the river network. A similar approach to integrate chemical emissions with a global hydrologic river network and associated flows can be employed to estimate local dilution factors and chemical concentrations across river network over countries where environmental concerns are a high priority. To address this specific need, the well-established Curve Number (CN) method was applied to develop a detailed surface runoff dataset. Publicly available, scientifically accepted and high-resolution global datasets for hydrologic soil groups, land cover, and precipitation were spatially processed by applying the CN equations to generate a contiguous global mean-annual surface runoff grid at a very high-resolution of 50m x 50m. Surface runoff was converted to river flow by spatially combining with a detailed global hydrology of rivers and catchment boundaries from HydroSHEDS and HydroBASINS to estimate mean-annual flows across the global river network. Evaluation of the estimated river flow was conducted against publicly available gage measurements in China and river flows in the Ohio River basin, U.S.; both showed high correlation (r2 = 0.70 for China and 0.97 for Ohio River). Applying the detailed global mean-annual river flows with broad-scale environmental exposure models like iSTREEM® provides a robust approach to assess ecological risk of chemicals used in home and personal care products, cosmetics, pharmaceuticals, etc. over large river basins, across a country, or at a continental scale.

R. Vamshi (Waterborne), K. McDonough (P&G), K. Stanton (ACI), A. Ritter (Waterborne).  High-Resolution Global Mean-Annual Surface Runoff And River Flow Datasets For Use In Risk Assessments. Poster, SETAC 2019. Platform 50. Toronto, Ontario, Canada.

PostersHome and Personal Care Products, Water/Wastewater Assessments2019

Moving toward a spatially-resolved global surface water flow and aquatic exposure model for consumer-use down-the-drain ingredients: Japan case study

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SETAC 2019, MP123
Toronto, Ontario, Canada
Session Title: Challenges in Characterizing Exposures to Organic Chemicals: Multiple Sources, Multiple Pathways and Multiple Scales
Monday, November 4, 2019
8:00 am, Exhibit Hall

Abstract:
Exposure assessment is a key factor in the environmental risk assessment (ERA) of consumer products that are disposed down-the-drain and involves estimating concentrations of ingredients in receiving waters. There is an opportunity to develop a globally-harmonized spatially explicit aquatic exposure model for down-the-drain ingredients by leveraging the growing availability of computational methods and large spatial datasets. Current models often assume average conditions across a country/region in a deterministic calculation, while, in reality, there can be substantial spatial variation in input parameters (e.g., emissions, per capita water use, and waste water treatment) across a region. While spatial variability has been addressed by some models, they have focused on a single country/region; and there is a need for a user-friendly, global aquatic exposure model on a single platform with a consistent approach, using best available data. The iSTREEM® model (American Cleaning Institute) is a spatially-explicit aquatic exposure model parameterized and evaluated primarily for the United States. The model has also been extended to China and evaluation has indicated excellent agreement between modeled and measured river flow data. There was also excellent agreement between case study modeled and monitored chemical concentrations. This platform was leveraged and extended to cover Japan and follows a framework that uses global datasets to estimate river flow on a catchment level, rout chemicals between catchments, and estimate catchment-specific concentrations. Each catchment is parameterized with a specific population, per capita water use, and waste water treatment plant (WWTP) information; and allows for spatial variation in emissions. For Japan, spatial locations of WWTPs were incorporated into the model and the resulting population served by WWTP treatment corresponds well with published reports of treatment levels. Direct discharge of grey water was included to represent current practice in some areas of Japan. Measured river flow data and case study chemicals with available monitoring data were used to evaluate the flow predictions and concentration distributions estimated by the model. Thus, this model framework provides a promising platform for expansion as a global aquatic exposure model for down-the-drain ingredients.

S. Csiszar (P&G), R. Vamshi (Waterborne), M. Fan (P&G), K. McDonough (P&G).  Moving toward a spatially-resolved global surface water flow and aquatic exposure model for consumer-use down-the-drain ingredients: Japan case study. Poster, SETAC 2019. MP123. Toronto, Ontario, Canada.

PostersWater/Wastewater Assessments2019

Modelling emissions of microplastics in Europe from wastewater sources, including land applied biosolids

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Abstract:
Public information regarding microplastics in the environment is frequently available and comes from a variety of sources, often in the form of retrospective sources such as measured aquatic data. Science-based risk assessment must utilize both retrospective and prospective exposure information to effectively estimate potential risk to ecological receptors. While monitoring data provide information at only a few locations for several points in time, prospective models can estimate the potential for ecological exposures across many landscapes and over long periods of time, and both have a role in risk assessment. Wastewater treatment plants are often cited as a source of microplastics entering the environment. Microplastics are highly removed (generally >90%) during the waste water treatment process, via skimming of floating particles or sorption to solids and settling into sludge. Understanding the eventual fate of this sludge, and the potential for contained microplastics to re-enter surface water, is one step of many in determining the fate of microplastics in the aquatic environment. Sludge management in Europe varies geographically, with up to 90% of sludge used on agriculture in Portugal, and 0% in other countries (Eurostat, 2017) with other disposal including incineration, landfill or composting. We present a model which addresses both direct aquatic emissions into surface water via waste water effluent, as well as indirectly from land applied biosolids coupled with spatially-defined surface runoff potential. Generalized runoff potential is estimated using fate and transport models used for plant protection products found in the EFSA FOCUS scenarios. To our knowledge, this coupling of direct aquatic emission and sludge-biosolids-runoff is a novel approach for examining environmental emissions of microplastics which enter municipal wastewater treatment plants. This spatially-explicit model is based on publicly available datasets, combined with a hydrologic framework containing geographically variable emissions linked to a river network simulating environmental transport via surface water.

Christopher Holmes, Joshua Amos, Amy Ritter, Marty Williams, and Scott Dyer (Waterborne Environmental). Modelling emissions of microplastics in Europe from wastewater sources, including land applied biosolids. Poster SETAC Europe 2019. Helsinki, Finland.

PostersWater/Wastewater Assessments2019

A prospective approach for assessing chemical mixtures in river catchments with diverse land uses

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Abstract:
Field-based ecological risk assessments incorporate risks from chemical mixtures and a myriad of stressors because ecosystems are continuously exposed to a wide-array of contaminants and nonchemical stressors. Considering the large numbers potential combinations of mixtures and stressors, this problem could seem insurmountable. We demonstrate that such combinations can be simplified by 3 land-use related chemical emission scenarios: agriculture, domestic, and urban. We applied a tiered methodology to assess the implications of each of the scenarios via a quantitative model. The results showed land use–dependent mixture exposures, clearly discriminating downstream effects of land uses, with unique chemical “signatures” regarding composition, concentration, and temporal patterns. Associated risks were characterized in relation to the land-use scenarios. Comparisons to measured environmental concentrations and predicted impacts showed relatively good similarity. The results suggest that the land uses imply exceedances of regulatory protective environmental quality standards, varying over time in relation to rain events and associated flow and dilution variation. Higher-tier analyses using ecotoxicological effect criteria confirmed that species assemblages may be affected by exposures exceeding no-effect levels and that mixture exposure could be associated with predicted species loss under certain situations. The model outcomes inform various types of prioritization to support risk management, including a ranking across land uses as a whole, a ranking on characteristics of exposure times and frequencies, and various rankings of the relative role of individual chemicals. Though all results are based on in silico assessments, our land use–based approach yields useful insights for simplifying and assessing potential ecological risks of chemical mixtures and can therefore be useful for catchment-management decisions.

Scott Dyer (Waterborne Environmental), Leo Posthuma (RIVM), Colin D. Brown (University of York), Dick de Zwart (RIVM), Jerome Diamond (Tetra Tech), Christopher Holmes (Waterborne Environmental), Stuart Marshall (Bedford, UK), and G. Allen Burton Jr (University of Michigan). A prospective approach for assessing chemical mixtures in river catchments with diverse land uses.
Poster SETAC Europe 2019. Helsinki, Finland.

Papers & ReportsWater/Wastewater Assessments2018

Simplifying environmental mixtures-An aquatic exposure-based approach via land use scenarios

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Posthuma, L., Brown, C., de Zwart, D., Diamond, J., Dyer, S.D., Hamer, M., Holmes, C.M., Marshal, S., Burton Jr., G.A. (2018), Simplifying environmental mixtures-an aquatic exposure-based approach via land use scenarios. Environ Toxicol Chem. 37: 671-673. doi.org/10.1002/etc.4063

Papers & ReportsWater/Wastewater Assessments2017

Prospective aquatic risk assessment for chemical mixtures in agricultural landscapes

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Environmental risk assessment of chemical mixtures is challenging because of the multitude of possible combinations that may occur. Aquatic risk from chemical mixtures in an agricultural landscape was evaluated prospectively in 2 exposure scenario case studies: at field scale for a program of 13 plant‐protection products applied annually for 20 yr and at a watershed scale for a mixed land‐use scenario over 30 yr with 12 plant‐protection products and 2 veterinary pharmaceuticals used for beef cattle. Risk quotients were calculated from regulatory exposure models with typical real‐world use patterns and regulatory acceptable concentrations for individual chemicals. The results could differentiate situations when there was concern associated with single chemicals from those when concern was associated with a mixture (based on concentration addition) with no single chemical triggering concern. Potential mixture risk was identified on 0.02 to 7.07% of the total days modeled, depending on the scenario, the taxa, and whether considering acute or chronic risk. Taxa at risk were influenced by receiving water body characteristics along with chemical use profiles and associated properties. The present study demonstrates that a scenario‐based approach can be used to determine whether mixtures of chemicals pose risks over and above any identified using existing approaches for single chemicals, how often and to what magnitude, and ultimately which mixtures (and dominant chemicals) cause greatest concern.

Holmes, C.M., Brown, C.D., Hamer, M., Jones, R., Maltby, L., Posthuma, L., Silberhorn, E., Teeter, J.S., St J Warne, M., Weltje, L. (2017), Prospective aquatic risk assessment for chemical mixtures in agricultural landscapes. Environ Toxicol Chem. 37: 674-689. doi.org/10.1002/etc.4049

Papers & ReportsHome and Personal Care Products, Water/Wastewater Assessments2017

Use of Prospective and retrospective risk assessment methods that simplify chemical mixtures associated with treated domestic wastewater discharges

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A framework is presented that is intended to facilitate the evaluation of potential aquatic ecological risks resulting from discharges of down‐the‐drain chemicals. A scenario is presented using representatives of many of the types of chemicals that are treated domestically. Predicted environmental chemical concentrations are based on reported loading rates and routine removal rates for 3 types of treatment: trickling filter, activated sludge secondary treatment, and activated sludge plus advanced oxidation process as well as instream effluent dilution. In tier I, predicted effluent concentrations were compared with the lowest predicted‐no‐effect concentration (PNEC) obtained from the literature using safety factors as needed. A cumulative risk characterization ratio (cumRCR) < 1.0 indicates that risk is unlikely and no further action is needed. Otherwise, a tier 2 assessment is used, in which PNECs are based on trophic level. If tier 2 indicates a possible risk, then a retrospective assessment is recommended. In tier 1, the cumRCR was > 1.0 for all 3 treatment types in our scenario, even though no chemical exceeded a hazard quotient of 1.0 in activated sludge or advanced oxidation process. In tier 2, activated sludge yielded a lower cumRCR than trickling filter because of higher removal rates, and the cumRCR in the advanced oxidation process was << 1.0. Based on the maximum cumulative risk ratio (MCR), more than one‐third of the predicted risk was accounted for by one chemical, and at least 90% was accounted for by 3 chemicals, indicating that few chemicals influenced the mixture risk in our scenario. We show how a retrospective assessment can test whether certain chemicals hypothesized as potential drivers in the prospective assessment could have, or are having, deleterious effects on aquatic life.

Diamond, J., Altenburger, R., Coors, A., Dyer, S.D., Focazio, M., Kidd, K., Koelmans, A.A., Leung, K.M.Y., Servos, M.R., Snape, J., Tolls, J., Zhang, X. (2017), Use of prospective and retrospective risk assessment methods that simplify chemical mixtures associated with treated domestic wastewater discharges. Environ Toxicol Chem. 37: 690-702. doi.org/10.1002/etc.4013

Papers & ReportsWater/Wastewater Assessments2017

Aquatic exposures of chemical mixtures in urban environments: approaches to impact assessment

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Urban regions of the world are expanding rapidly, placing additional stress on water resources. Urban water bodies serve many purposes, from washing and sources of drinking water to transport and conduits for storm drainage and effluent discharge. These water bodies receive chemical emissions arising from either single or multiple point sources, diffuse sources which can be continuous, intermittent, or seasonal. Thus, aquatic organisms in these water bodies are exposed to temporally and compositionally variable mixtures. We have delineated source‐specific signatures of these mixtures for diffuse urban runoff and urban point source exposure scenarios to support risk assessment and management of these mixtures. The first step in a tiered approach to assessing chemical exposure has been developed based on the event mean concentration concept, with chemical concentrations in runoff defined by volumes of water leaving each surface and the chemical exposure mixture profiles for different urban scenarios. Although generalizations can be made about the chemical composition of urban sources and event mean exposure predictions for initial prioritization, such modeling needs to be complemented with biological monitoring data. It is highly unlikely that the current paradigm of routine regulatory chemical monitoring alone will provide a realistic appraisal of urban aquatic chemical mixture exposures. Future consideration is also needed of the role of nonchemical stressors in such highly modified urban water bodies.

de Zwart, D., Adams, W., Burgos, M.G., Hollender, J., Junghans, M., Merrington, G., Muir, D., Parkerton, T., De Schamphelaere, K.A.C., Whale, G., Williams, R. (2017), Aquatic exposures of chemical mixtures in urban environments: Approaches to impact assessment. Environ Toxicol Chem. 37: 703-714. doi.org/10.1002/etc.3975