The Stone-Intrinsik Team was proud to attend the  SETAC North America 40th Annual Meeting in Toronto, Canada on November 3rd-7th. We always relish the chance to be a part of this week-long conference featuring a variety of training, networking, and learning opportunities focused on bringing together environmental scientists and managers from all sectors to address shared environmental challenges at a global scale through collaboration and collective solutions.

Our posters and presentation schedule can be found below. For additional information about SETAC Toronto, please visit the conference website.

monday poster presentations

SESSION: Mining Environments in a Changing Climate (Exhibit Hall), Environmental Risk Assessment Track

8:00 am: Customized Reactive Capping Blend for Enhancing Natural Recovery of Wetlands Impacted by Contaminated Legacy Gold Mine Tailings (MP239)

E. Chapman, Saint Mary's University; C.E. Moore, Intrinsik Corp.; L.M. Campbell, Saint Mary's University / Department of Environmental Science

Gold mine tailings generated in the late 1800’s still contains elevated concentrations of mercury (Hg) due to the amalgamation process used to extract the gold, and arsenic (As) due to the naturally high levels of arsenopyrite present in gold-bearing rock. At that time, before environmental legislation, tailings were simply discarded into nearby lakes, wetlands or rivers without treatment. More than a century later, multi-generational exposure to tailings has occurred, potentially impairing ecosystem function and impeding biological recovery. Innovative, non-intrusive, low-cost approaches are urgently needed to manage risks associated with legacy tailings in sensitive aquatic habitats. The purpose of this project was to complete proof of concept testing of customized capping blends for limiting the mobility, bioaccumulation and toxicity of Hg and As in wetland sediment impacted by legacy tailings. Sediment was collected from two wetlands in historical gold mining districts. A clean control sediment was also prepared mimicking the texture of the contaminated sediments. Capping applications were assessed in terms of success in limiting the toxicity and bioaccumulation of contaminants in invertebrates exposed to the sediments, as well as the ability of the capping blends to reduce mobility of contaminants from the sediment to the water column. Due to the extremely high concentrations of Hg and As, invertebrates exposed to untreated contaminated sediment exhibited high mortality, growth impacts, and high bioaccumulation of both contaminants. The capping application that showed best results in limiting these impacts was a blend of fine silica sand, two different clays, and zeolite-supported nanoscale zerovalent iron slurry. This capping blend dramatically improved the survival of Hyalella azteca and Daphnia magna to levels observed in clean control sediments, and significantly reduced the bioaccumulation of Hg in Caridina multidentate. Furthermore, in the overlaying water column of capped sediments, concentrations of Hg and As were reduced by 88% and 99% respectively. Our proof of concept bench top testing with this capping blend shows potential. However, before the capping blend can be used in the field to reduce risks it is necessary to complete testing using more environmentally realistic mesocosms.

SESSION: Environmental Risk Assessment (Exhibit Hall), Environmental Risk Assessment Track

8:00 am: The Utility of the Avian Toxicity Test in Ecological Risk Assessment and a Path Forward for Reduction in Animal Use (MP302)

A. Bone, Bayer CropScience / Environmental Safety; L.W. Brewer, Compliance Services International / Department of Wildlife Toxicology; C. Habig, Compliance Services International; S. Levine, Bayer AG - Crop Science Division / Regulatory; D. Moore, Intrinsik Ltd.; S.R. Mortensen, BASF Corporation; S. Plautz, BASF / The Institute of Environmental and Human Health

There is a long history of the US EPA requiring both avian short-term dietary and acute oral studies to inform avian risk assessment for pesticides. Recently, the US EPA collaborated with People for the Ethical Treatment of Animals (PETA) to determine whether the results of the acute oral avian toxicity test or the short-term dietary toxicity test drove the avian acute ecological risk assessments (ERAs) for pesticides from 1998-2016. Their study concluded that in 99% of the cases, the dietary study did not change the risk conclusions derived using the acute oral study (OPPTS 850.2100, OCSPP 850.2100 or similar). Therefore, EPA and PETA suggested waiving the dietary study for most plant protection products to reduce the number of birds used for testing. However, besides being a relevant study for plant protection products with certain chemical properties, the avian short-term dietary study has a feeding regimen that is more representative of how birds forage in the field than does the acute oral study.  The dietary study can be an important refinement in a higher tiered ERA.  Decision criteria are needed to determine a path forward that accomplishes the goal of reducing vertebrate animal testing but also allows for the use of the avian dietary study in risk refinement. The first goal of this project is to develop such criteria. Second, we will provide recommendations to address the design of avian dietary studies to ensure that the data are optimized to support an acute avian assessment. In addition, we will provide case studies to demonstrate the use of the criteria to decide when a dietary study could be used as a higher-tier refinement and how the study should be designed to support use in standard FIFRA and endangered species assessments.

TUESDAY PLATFORM & POSTER PRESENTATIONS

POSTER SESSION: Estimating Environmental Hazard and Risks from Exposure to Perfluorinated and Polyfluorinated Alkyl Substances (PFAS): Outcome of a Focused Topic Meeting (Exhibit Hall), Environmental Risk Assessment Track

8:00 am: Modeling of Potential PFAS Leaching from Land Applied Biosolids to Groundwater (TP246)

M. Propato, M.F. Winchell, Stone Environmental, Inc.; N. Beecher, NEBRA

One source of potential concern for the entry of PFAS into the environment is the land application of biosolids. Biosolids, often from municipal wastewater treatment facilities, are most often applied to agricultural land to provide nutrients required for plant growth. Due to the ubiquitous nature of PFAS in our society, their presence in wastewater biosolids is often detected at variable concentration levels. Understanding the limits to the concentrations of PFAS in land applied biosolids that are required to be protective of groundwater sources for drinking water is of high importance. Screening level approaches for estimating PFAS concentration limits in agricultural soils have been largely derived from contaminated sites, which assume a very different conceptual model than a biosolids application to cropland. The use of inappropriate models in deriving regulatory concentration limits on PFAS in biosolids has the potential to result in mismanagement of biosolids as a beneficial resource. An approach to modeling the leaching of two common PFAS chemicals, PFOA and PFOS, was developed based on contaminant transport modeling used by US EPA in the regulation of agriculturally applied pesticides. The Pesticide Root Zone Model (PRZM) predicts surface runoff, erosion, and leaching of chemicals applied at the land surface, and accounts for sorption/desorption and multiple degradation processes when relevant. The PRZM model was applied to evaluate the potential for PFOA/PFOS leaching to groundwater in Maine, and to estimate biosolids concentration limits required to protect groundwater resources. A spatial analysis of cultivated cropland and pasture/hay land in Maine was conducted to identify four representative soils in these areas, ranging from sandy low water holding capacity soils to clay high water holding capacity soils. These four soils were used to parameterize the PRZM model using Maine specific weather and crop growth parameters. An ensemble of model simulations, evaluating a range of sorption characteristics (Kd), groundwater depths, and biosolids application rates, provided data that allowed for better informed determination of the relationships between PFAS concentrations in land applied biosolids and their presence in ground water.

POSTER SESSION: Ecological Risk Assessment: What Matters and Prioritization of Resources (Exhibit Hall), Environmental Risk Assessment Track

8:00 am: Practical Advancements in Endangered Species Risk Assessment Efficiency (TP253)

S. Teed, Intrinsik Corp.; M.E. Kern, Waterborne Environmental, Inc. / Ecotoxicology Risk Assessment; J.L. Cowles, NovaSource / Tessenderlo Kerley, Inc. / Product Safety

With the release of the Environmental Protection Agency (EPA) and National Marine Fisheries Service (NMFS) organophosphate case studies for endangered species risk assessment, it became clear that the methods used in the biological evaluations and biological opinion need refinement for identifying risk to listed species and the critical habitat on which they may depend. With hundreds of pesticide registration actions annually, and more than 1,660 species listed under the Endangered Species Act, it is critical to be able to conduct a scientifically defensible risk assessment efficiently with limited time and resources. However, confidence must be high that the listed species or the critical habitat on which they depend can readily be identified as being not at risk, or at potential risk. The recently released EPA revised method for developing biological evaluations addresses some aspects of these short comings, by recognizing early in the problem formulation process that some listed species will not be exposed to a pesticide for a variety of reasons (e.g., they are extinct or extirpated; only found on federal lands). However, there are many possible additional considerations that matter, can be accounted for, and may vary on a pesticide by pesticide basis. These include label restrictions, simple spatial refinement, specific fate/behavior characteristics, listed species life history information, known and previously evaluated pesticide tolerances, and other factors. In a CropLife America funded project, these practical advancements are being identified and evaluated for use in the problem formulation process. In this presentation, the carbamate pesticide carbaryl is used to evaluate the impact of these factors on the endangered species risk assessment process, along with examples from other chemistries to more clearly show their utility.

POSTER SESSION: Site-Specific Risk Assessment of Soils Impacted by Petroleum Hydrocarbon Mixtures: State of Science and New Approaches (Exhibit Hall), Environmental Risk Assessment Track

8:00 am: Organic Carbon Normalization and Relevance of Species Assemblages for Soil Ecological Risk Assessments of Petroleum Hydrocarbon Contaminated Soils (TP269)

A. Gainer, SNC-Lavalin / Soil Science, Toxicology; N.S. Hogan, University of Saskatchewan / Department of Animal and Poultry Science and Toxicology Centre; K.E. Bresee, Intrinsik Corp.; S. Siciliano, University of Saskatchewan / Department of Soil Science

Sediment toxicity studies and ecological risk assessments on organic contaminants routinely apply organic carbon normalization to toxicity data; however, no studies examine its potential for use in soils with petroleum hydrocarbon (PHC) contamination. Limited studies in soil ecotoxicology assess the influence of species assemblages used in species sensitivity distribution construction on the resulting guideline designated to of soil dwelling organisms. Canadian regulations utilize more conservative approaches to deriving guidelines with soil ecotoxicology data compared to the rest of the world, so we investigated the impact of these on soil invertebrates in a variety of field soils. In addition to toxicity, the persistence of a medium PHC mixture was also assessed in the field soils to determine the duration of toxic effects. We found organic matter influenced PHC toxicity to soil invertebrates, but persistence was influenced more by soil cation exchange capacity. Incorporating organic carbon normalization into species sensitivity distribution curves provided a higher level of protection to soil dwelling receptors in low organic matter soils as well as reduce the variability of PHC soil toxicity data. Soil remediation guidelines derived for protection of soil dwelling organisms using a diverse species assemblage provided similar levels of protection as guidelines developed with test species specific for remote, forested land uses in Canada. We conclude that: (i) Canadian hazard concentration values for PHC contamination of soils should be revisited as they may not be protective and (ii) that soil PHC guidelines for protection of soil dwelling organisms should be expressed as carbon normalized values.

POSTER SESSION: Pesticides and Pollinators: Assessing Potential Risks at Colony and Population Level (Exhibit Hall), Environmental Risk Assessment Track

8:00 am: A Semi-field Tunnel Study Using the Common Eastern Bumble Bee (Bombus impatiens) (TP279)

L. Richardson, J. Hanzas, Stone Environmental, Inc.; S. Perez, Adpen Laboratories, Inc.

Ecological risk assessment is a key component of the regulatory process required for registration of crop protection products in the US and elsewhere. The western honey bee (Apis mellifera) is the established test organism for assessing pesticide exposure risk to pollinating bees, yet there is concern that it is not a suitable surrogate for other bees in all circumstances. Accordingly, efforts are underway in Europe to adapt honey bee test methodologies for two types of native bees, bumble bees and mason bees. The buff-tailed bumble bee (Bombus terrestris), a test species in Europe, may not be imported to North America, meaning that such risk assessment studies will have to be conducted here using a species native to the area, the common eastern bumble bee (B. impatiens). To address this need, in 2019 we are conducting a higher-tier field study with B. impatiens. Adapting semi-field study guidelines for honey bees (e.g., EPPO 170 and OECD 75) and benefiting from similar work with B. terrestris in Europe, we grew 3 hectares of the bee-attractive plant curly phacelia (Phacelia tanacetifolia) on a Vermont, USA farm. We constructed 18 caterpillar tunnels, each 60 m2 area, over the crop, and at onset of flowering, introduced one commercial B. impatiens colony to each tunnel. Six replicate tunnels were randomly assigned to each of three treatments: a negative control where plants were sprayed only with water, and low and high concentration applications of the insecticide dimethoate. Following applications made with a handheld spray boom, analytical samples will be collected to verify application rates, nectar and pollen residues, and realized dietary exposure to bees. After 14 days of confinement to tunnels, all colonies will be moved outside to forage on untreated floral resources. The primary endpoint to be quantified is number and mass of new gynes (queens) produced by colonies. In addition, we are collecting data on production of male offspring, worker mortality, foraging behavior, and colony growth. Our work is novel in that it is the first fully-replicated semi-field tunnel study to be conducted using B. impatiens, a key component of future risk assessment research for non-Apis bees in North America. We anticipate that our methods and results can guide future efforts to develop a standard test paradigm to assess risk of crop protection products to bumble bees.

POSTER SESSION: Wildlife Ecotoxicology: Assessing Effects of Chemical Stressors at Multiple Scales (Exhibit Hall), Environmental Risk Assessment Track

8:00 am: Health Assessment of Bighorn Sheep and Elk Populations on a Mine Using GPS Tracking and Tissue Sampling (TP343)

C.B. Meyer, M. Batchelder, ARCADIS US, Inc; H. McChesney, T. Cox, ARCADIS; C. Lambert, Intrinsik Ltd.; B.E. Sample, Ecological Risk, Inc.; C.L. Murray-Gulde, Chevron Environmental Management Company

In wildlife ecotoxicology studies, directly sampling chemical concentrations in individuals of free-ranging wildlife and monitoring their movements and diets provides an opportunity to identify population-level patterns of exposure and effects.  This information can be used to inform remedial decisions. To assess effects from metals exposure to bighorn sheep populations that forage on a large mine and to elk populations that forage on the mine tailing facility, bighorn ewes and elk cows were captured. They were fitted with GPS collars to monitor herd foraging patterns on and off site for one year.  Blood, hair and feces were collected from each collared individual to provide an indicator of metal uptake and overall health of each herd. Blood analyses included cell counts and biochemical parameters. The health of nearby reference herds was monitored at the same time through tissue collection.  A dietary analysis of the elk herd for each season was conducted using DNA in feces. Tracking results indicate that bighorn sheep spent 13 to 22% of their time on the mine, depending on the season. They had elevated molybdenum levels in tissues but showed no indication of adverse effects on measured health parameters. Changes in exposure after mine reclamation were then predicted using landscape-scale habitat modeling. Planned reclamation will convert molybdenum exposure areas from waste rock piles to a seeded mine cover designed to transition to shrubland vegetation. Using innovative techniques, the habitat models predicted new home range contours and use patterns for post-reclamation populations. These models predicted that, after shrub development on the cover post-reclamation, bighorn sheep will spend approximately 16 to 20% of their time on the reclamation cover, which is similar to time spent on the mine prior to reclamation. Tracking results indicated that the elk herd foraged on the tailing facility 14% of the time.  Tissue analysis indicated that elk had marginal copper deficiency in their blood and/or liver. However, the elk experienced no ill effects on their health as determined by a veterinarian and one necropsy. 

PLATFORM SESSION: Approaches for Understanding Diversity in Species Sensitivity to Chemicals (Room 714B), Environmental Risk Assessment Track

1:20 pm: Correcting for Phylogenetic Autocorrelation in Species Sensitivity Distributions (#296)

D.R. Moore, C. Priest, Intrinsik, Ltd.; N. Galic, R. Brain, Syngenta Crop Protection, Inc. / Environmental Safety; S.I. Rodney, Intrinsik Corp.

A species sensitivity distribution (SSD) is a modeled cumulative distribution function of toxicity endpoints for a specified receptor group. SSDs are frequently used to derive environmental benchmarks or to characterize risk to hypothetical sensitive species or to entire taxonomic groups or communities. A key statistical assumption when deriving an SSD is that the toxicity data points are independent and identically distributed (iid). This assumption is tenuous, however, as closely related species tend to have similar sensitivities, whereas more distantly related species often have divergent sensitivities. When the response of one species can be at least partially predicted by the response of another species, there is a dependency or autocorrelation in the dataset. To date, phylogenetic relationships and the resulting dependencies in input datasets have been ignored in deriving SSDs. In this paper, we explored the importance of the phylogenetic signal in deriving SSDs using a case studies approach. The case studies involved toxicity datasets for aquatic autotrophic species exposed to atrazine and aquatic and avian species exposed to chlorpyrifos. Full and partial datasets were included to enable exploration of the influences of differing phylogenetic signal strength and sample size. The results indicated that the phylogenetic signal was significant for some of our toxicity datasets (i.e., the chlorpyrifos datasets for all aquatic species, all vertebrate species, all invertebrate species, and fish species) but not for others (i.e., the atrazine full and sub datasets, the chlorpyrifos datasets for all insects, crustaceans and birds). When a significant phylogenetic signal did occur, the result was a reduced effective sample size. The reduction was rather large when the signal was strong. In spite of the reduced effective sample sizes, significant phylogenetic signals had little impact on fitted SSDs, even in the tails (e.g., HC5 values). The lack of a phylogenetic signal impact occurred even when we artificially reduced original sample size and increased strength of the phylogenetic signal. We conclude that it is good statistical practice to account for the phylogenetic signal when deriving SSDs because many multi-species toxicity datasets do not meet the independence assumption. That said, SSDs and HC5 values appear to be robust to deviations from the independence assumption.

WEDNESDAY PLATFORM & POSTER PRESENTATIONS

POSTER SESSION: Concentrations and Thresholds for Effects of Current Use Pesticides in Aquatic and Terrestrial Ecosystems (Exhibit Hall), Environmental Risk Assessment Track

8:00 am: Aquatic Exposure Modeling of Consumer-Applied Residential Use Pesticides Using Refined Inputs (WP110)

S. Castro-Tanzi, M.F. Winchell, Stone Environmental, Inc.;Stone Environmental, Inc.; W.E. Hillwalker, SC Johnson / GSARA

Empirical data from various sources can be useful for deriving realistic inputs and assumptions to standard regulatory models that serve as the basis for refined ecological risk assessments. Recent screening-level regulatory aquatic exposure modeling and risk assessments of consumer-use pesticides containing synthetic pyrethroids and pyrethrins assume application practices that are characteristic of applications by licensed professionals. However, this assumption may not reflect actual use patterns nor the intended use of certain consumer product formulations. Here we present the procedures and results of a refined outdoor residential exposure assessment designed to evaluate specific consumer products containing different pyrethroid insecticide active ingredients with a range of treatment sites and delivery mechanisms. We used the Pesticide in Water Calculator model (PWC) to estimate water and sediment pyrethroid concentrations in residential receiving waters. Refined model assumptions and PWC inputs were obtained from various sources, including: data on actual consumer pesticide use practices as reported in the Residential Exposure Joint Venture (REJV) database, labeled use sites for specific consumer residential products, and best available environmental fate data reported in public comments responding to the EPA’s pyrethroid Preliminary Risk Assessment (PRA). When compared to existing screening-level estimated environmental concentrations (EECs), predictions produced in our analysis were 2 to 6 orders of magnitude smaller. Our analysis highlights the usefulness of supplementary data sources in realistically parametrizing refined exposure models to asses ecological risk of consumer products.

PLATFORM SESSION: Plants in Environmental Risk Assessment: Assessing and Predicting the Effects of Chemicals on Plant Communities (Room 713B), Environmental Risk Assessment Track

10:40 am: A Field Spray Drift Study to Determine Downwind Effects to Non-target Plants (#498)

D. Moore, Intrinsik Ltd.; L.S. Ortego, Bayer CropScience / Environmental Toxicology and Risk Assessment; R.J. Isemer, Bayer Ag / Environmental Safety - Environmental Effects; T. Xu, Bayer AG Crop Science Division / Environmental Fate; J. Tang, Bayer AG Crop Science Division / Environmental Exposure Assessment; T. Hall, Bayer CropScience / Environmental Toxicology and Risk Assessment; A. Chapple, Bayer Crop Science AG; Y. Yang, BayerCropScience / Environmental Fate; J. Hanzas, B. Brayden, K. Watson, Stone Environmental, Inc.; S.I. Rodney, Intrinsik Corp.; C. Banman, SynTech Research, Inc. / Ecotoxicology

A spray drift and associated vegetative vigor study was performed to determine the off-field drift deposition and potential toxicity of a herbicide to sensitive non-target plants at various distances downwind from the treated area. Each treatment consisted of four 100 foot wide spray swaths that ran perpendicular to the target wind direction. There were three trials and each was performed on a 515 foot x 334 foot area that included the upwind control plants, treated area, and downwind plants.. One trial had vegetation (approximately 12” tall mowed grass; typical scenario) in the downwind deposition area and two trials had bare ground deposition areas (worst-case scenario). Drift collectors placed 5, 30, 50, 75, and 100 feet downwind of the application area were analyzed for herbicide residues. Pots of lettuce and navy bean plants (2-4 leaf stage), two species known to be sensitive to the herbicide, were placed 5, 30, 50, and 100 feet downwind of the application areas. There were 25 replicate pots/species at each downwind distance and 50 replicate pots/species for the corresponding upwind controls. Each pot had 2 plants and plant height was determined prior to application for use as a covariate in the statistical analyses. The lettuce and navy bean plants were subsequently grown out in a greenhouse for 28 and 21 days, respectively. Plant survival, growth stage, phytotoxicity, and height were assessed at 7, 14 and 21 days after treatment (DAT) for all plants and at 28 DAT for lettuce. Dry weight was determined at test termination. No effects occurred to either test species placed in downwind vegetation at any distance. No statistical differences from controls were observed in navy bean or lettuce shoot height or weight at downwind distances of 30 feet or further from the edge of the application area for plants placed on bare ground. The field study results contrasted sharply with the high/larger predicted effects and effect zones that can result from using modeled spray drift curves and greenhouse bioassays with direct overspray exposure. This study confirms that comparing spray drift modeled exposure estimates to the greenhouse bioassay results can seriously over predict effects to downwind non-target plants.

THURSDAY PLATFORM PRESENTATION

SESSION: Integration Pest Management, Risk Assessment and Environmental Sustainability (Room 718B), Environmental Risk Assessment Track

10:20 am: Refinement of Pesticide Exposure Estimates through Robust Incorporation of Spatial Datasets (#688)

M.F. Winchell, H. Rathjens, Stone Environmental, Inc.

A critical component to advancing pesticide ecological risk assessments is the improvement of pesticide exposure estimates across the landscape. Numerous environmental factors contribute to variability of pesticide exposure potential in both space and time. Traditional screening level approaches to estimating pesticide exposure make generalizations in landscape characteristics that lead to conservative scenarios assumed to apply over broad geographic regions. This generalization of conservative exposure predictions does not allow for the identification of actual locations and conditions that lead to the highest exposure risk, which in turn does not allow for the adoption of conservation measures that result in the greatest ecological benefit. Methods and data sets that allow for spatially explicit predictions of pesticide exposure have been developed over the past decade or longer and are gradually making their way into more routine ecological exposure and risk assessments. Many of these methods relay upon multiple years of high-resolution land use and crop data sets at the national scale to characterize potential pesticide use sites and are coupled with high resolution landscape data sets, such as elevation, slope, and hydrography. Application of these methods allow for prediction of probabilistic pesticide exposure distributes at a spatial scale, such as a water body or small catchment, that can more accurately assess risk to ecological communities or individual species and strategically target effective conservation measures. Examples of these spatially explicit pesticide exposure modeling approaches will be presented along with a discussion on how barriers to their wide implementation in ecological risk assessments might be overcome.