Landscape-Level Refinements for Probabilistic Pyrethroid Exposure Assessments in Agricultural Environments
The Pyrethroid Working Group (PWG) has conducted a probabilistic refinement of aquatic exposure estimates for agricultural pyrethroid uses incorporating step-wise refinements to standard USEPA Tier II exposure modeling scenarios. Weather, soils, cropping and other environmental factors were summarized to over 2.5 million catchments in the USGS NHD+ dataset, and used to model the national range of crop-specific potential pyrethroid drift and runoff/erosion transport to surface water. Using over 375,000 PRZM runs incorporating local cropping, weather and soils data, along with NHD+ flowline specific drift estimates for each catchment, a matrix of 11 representative drift rates and 10 representative runoff/erosion PRZM runs was created for each crop of interest. This was used to develop a set of 110 scenarios, each representing a specific proportion of the distribution. Probabilities for each matrix bin were computed based on the actual catchment area represented by each combination of drift and runoff/erosion nationally. Each of the 110 scenarios was modeled by linking PRZM, VFSMOD and AGRO-2014 to produce 30 year distributions of annual maximum aquatic EECs. The combined set of annual maximum EEC values along with the weighting matrix, were used to generate a distribution of crop-specific EECs suitable for probabilistic risk characterization. This approach allowed other variables (e.g. the percentage of each crop treated with any pyrethroid insecticide) to be readily incorporated into the probabilistic assessment. Resulting potential exposure distributions for ten different crops were used in multiple pyrethroid risk assessments submitted to USEPA.
By: Chris Holmes, Paul Hendley, Josh Amos, Amy Ritter, Mark Cheplick, Dean Desmarteau, Russell Jones, Scott Jackson, Russell Underwood
Conference: SETAC North America 35th Annual Meeting
Date: Thursday, November 13, 2014
Duration: 15 Minutes
Presenter: Chris Holmes
Review of Pesticide Environmental Fate Parameters and Their Quantitative Relationship With Soil and Climate Conditions
Pesticide sorption and degradation in soil are two critical, interlinked and extensively studied processes for assessing a pesticide’s potential environmental mobility and persistence. There is a wealth of data on this in published literature. This presentation summarizes the results of a recent IUPAC research project (2010-018-2-600) focusing on quantitative relationships of the environmental fate processes of pesticide with broader soil properties, climate variables, and potential molecular structure-activity influencing their fate and behavior. The coupling relationship of degradation with sorption in soil and its implications for determining the bioavailability and biodegradability factors will be discussed. Calibration of the reviewed data with local environmental conditions is explored to improve fate parameter estimation. This may directly benefit data deficient regions with limited pesticide fate studies (e.g. tropical soils, and scientifically emerging regions in Africa, Asia and South America). Results are also expected to provide valuable information for the refinement of pesticide environmental exposure assessment models in general.
Wenlin Chen, William Koskinen, Annemieke Farenhorst, Volker Laabs, Amy Ritter, Rai Kookana, Aleksandar Sabljic, Robin Sur, Riaz Ahmad, Elizabeth Carazo, Jairo A. Guerrero D. Karina S.B. Miglioranza, Veronica Cesio, Junying Zhou. (1) Syngenta Crop Protection, LLC, Greensboro, NC, United States, (2) University of Minnesota, United States, (3) University of Manitoba, Canada, (4) BASF, Germany, (5) Waterborne Environmental, Inc, United States, (6) CSIRO Land and Water, Australia, (7) Institute Rudjer Boskovic, Croatia, (8) Bayer CropScience LP, United States, (9) Punjab Agricultural Research Board, Pakistan, (10) Universidad de Costa Rica, Costa Rica, (11) Universidad Nacional de Colombia, Colombia, (12) Universidad Nacional de Mar del Plata, Argentina, (13) Universidad de la República, Uruguay, (14) Nanjing Institute of Environmental Science, China
Refining Pyrethroid Aquatic Exposure Assessments By Incorporating Measured Landscape and Environmental Variability Using Probabilistic Approaches. III – Characterizing the Probability of Wind Speeds and Direction Across Multiple Insecticide Applications Within a Season
The Pyrethroid Working Group (PWG) is conducting a probabilistic refinement of aquatic exposure estimates for agricultural pyrethroid insecticide uses. This presentation will focus on potential aquatic ecological exposure from drift due to pyrethroid use on crops. Because many pyrethroid use patterns permit multiple aerial applications, using 16 meteorological stations nationally, PWG has investigated the likelihood of occurrence that the wind will be blowing towards the water body at or above 10 mph on every application day at all Tier II exposure scenario locations. Using hourly wind speed and direction data for SAMSON weather stations, an analysis was performed for early morning or early evening application hours for “n” applications occurring “m” days apart (as specified for a particular crop on pyrethroid labels) for a range of feasible start dates for 30 weather years. Additionally, the presentation examines the probabilistic distribution of annual loadings from aerial drift to the standard pond when the actual wind speed, temperature, humidity and wind direction on the day of application are considered (AgDRIFT® aerial Tier II) compared to annual loadings using AgDRIFT® aerial Tier I default values. These loadings were compared to EPA Tier II assumptions and also incorporated directly into some example AGRO-2014 model runs to compute estimated environmental concentrations (EECs). Inclusion of wind speed, direction and associated meteorological drift drivers significantly modified the estimated distribution of annual maximum EECs via significant decreases of most annual loadings.
Amy M Ritter, William Northcott, Paul Hendley, Megan L White. (1) Waterborne Environmental, Inc., Leesburg, VA 20175, United States, (2) Phasera Ltd., Bracknell, Berkshire RG12 2JJ, United Kingdom
PostersCrop Protection, Water/Wastewater Assessments2014
iSTREEM® – A Web-based River Chemical Concentration Estimation Model for Consumer Pesticide Product Chemicals
In recent years, attention to anthropogenic chemicals in the environment has expanded beyond conventional industrial chemicals and agricultural pesticides to include those used in everyday consumer products such as pharmaceuticals, cosmetics, cleaning products and consumer pesticide product chemicals. Although there is more interest, researchers are often not familiar with use patterns of consumer product ingredients and therefore have more difficulty estimating exposures and impacts to aquatic environments. The American Cleaning Institute developed iSTREEM®, a publicly-available, web-based computer model that predicts the concentration in the environment of chemicals used in products typically disposed of ‘down-the-drain’. iSTREEM®estimates concentration in the effluent of more than 10,000 wastewater treatment plants throughout the continental United States, their resultant mixing zones and downstream river reaches (more than 25,000) and at 1,700 drinking water intakes downstream of wastewater discharges (http://www.cleaninginstitute.org/science/istreem.aspx). The data are geo-referenced permitting combination with similar data sets to reveal spatial relationships. By estimating freshwater exposures, the model permits scientists to understand where the greatest potential chemical risks may lie and how to best develop environmental monitoring programs. Likewise, it is a tool that can be utilized in setting public policy regarding freshwater discharges and pollution prevention. The presentations will feature an application of the model for N,N-Diethyl-m-toluamide (DEET), which is reaching the environment mainly from consumer use of DEET-containing insect repellent. Results will be compared to aquatic toxicity benchmarks to provide a screening-level estimation of risk that may be suitable for regulatory purposes.
iSTREEM® – A Web-based River Chemical Concentration Estimation Model for Consumer Pesticide Product Chemicals. Christopher M Holmes, Paul C DeLeo, John A Weeks, Katherine E Kapo. Poster presentation by Christopher Holmes. ACS/IUPAC 2014.
PostersAgriculture and Food, Crop Protection2014
Refining Pyrethroid Aquatic Exposure Assessments by Incorporating Measured Landscape and Environmental Variability using Probabilistic Approaches. I – Overview – Concepts for Refining Lower Tier Exposure Estimates
Regulatory aquatic exposure modeling at lower tiers typically uses standard scenarios based on assumptions designed to ensure model output is extremely conservative. To improve the accuracy of lower tier exposure assessments, these assumptions need to be examined to prioritize opportunities for refinement. Selected refinements should be quantifiable as numerical distributions of real-world variability which can be incorporated into exposure assessment frameworks via probabilistic modeling. National and regional distributions of landscape-related runoff and drift load transport from treated areas into receiving waters are an important and quantifiable source of variability in lower tier aquatic assessments. Additionally, for uses incorporating multiple aerial applications each season, the real-world co-occurrence of wind speed/direction across sequential seasonal applications has significant and quantifiable variability. The combined effect of these two real-world distributions on probabilistic distributions of potential aquatic pyrethroid exposure is a very significant reduction relative to lower tier predictions. However, other unchanged scenario assumptions ensure the predictions remain conservative.
Paul Hendley, Amy M. Ritter, Chris M. Holmes, Dean A. Desmarteau. (1) Phasera Ltd., Bracknell, Berkshire RG12 2JJ, United Kingdom, (2) Waterborne Environmental Inc., Leesburg, VA 20175, United States
PostersAgriculture and Food, Crop Protection2014
Refining Pyrethroid Aquatic Exposure Assessments by Incorporating Measured Landscape and Environmental Variability using Probabilistic Approaches. IV – Comparison of Aquatic Exposure Estimates for Pyrethroid Crops based on Real-world Inputs and Standard Lower Tier Regulatory Estimated Concentrations.
The Pyrethroid Working Group (PWG) has conducted a probabilistic refinement of aquatic exposure estimates for agricultural uses. PWG has characterized potential vulnerabilities of the US nationwide landscape for key pyrethroid use patterns in terms of the potential for drift and runoff entry at the NHD+ catchment spatial scale in areas where the crop is currently produced, the likelihood of multiple applications all having adverse wind speeds and directions and also the potential impact of many other factors associated with well documented pyrethroid behaviors. The first two factors have been defined as numerical probability distributions which can be translated into input assumptions for EPA standard farm pond scenario modeling using PRZM-AGRO-2014 for comparison with output from EPA’s standard lower tier model scenarios. The results show that the probabilistic assessments generate exposure distributions that are dominated by results from catchments with zero to low cropping densities. This, coupled with the fact that most crops are not grown extensively on extremely erosive slopes/soils, means that standard lower tier regulatory exposure estimates only reflect the upper bounds of real-world potential exposures. Additional factors related to pyrethroid behaviors mean that even these probabilistic pyrethroid model outputs over-predict likely real-world concentrations. These results are supported by monitoring data.
Paul Hendley, Chris M. Holmes, Amy M. Ritter, Dean A. Desmarteau. Phasera Ltd., Bracknell, Berkshire RG12 2JJ, United Kingdom, Waterborne Environmental Inc., Leesburg, VA 20175, United States
Refining Pyrethroid Aquatic Exposure Assessments by Incorporating Measured Landscape and Environmental Variability using Probabilistic Approaches. II – Characterizing Nationwide Landscape Vulnerability for Several Pyrethroid Crops
The Pyrethroid Working Group (PWG) is conducting a probabilistic refinement of aquatic exposure estimates for agricultural pyrethroid uses. Landscape variability, as it affects the potential for pyrethroid runoff and drift loads to enter receiving water bodies, was identified for quantification in this analysis. In a national assessment, for every NHD+ catchment containing the crop of interest (CoI), potential vulnerability was estimated using the percent of CoI in the 200m proximity zone around the NHD+ stream reaches to reflect potential drift loading. Erosion/runoff loading potential of each NHD+ catchment was ranked using the crop area-weighted 30-year median PRZM model output for all CoI cropped soils in the catchment with local weather stations. These two parameters were plotted for each catchment in each of 10 or 11 bins using a 2-D matrix to characterize the distribution of nationwide landscape vulnerabilities. Each matrix of 110 combinations for soil / weather / PCA / proximity was modeled using PRZM/VFSMOD/AGRO-2014 and RegDisp/AgDRIFT to calculate 30 years of annual maxima EECs. Results were weighted by the actual occurrence in the national distribution, resulting in a distribution of 3330 EECs suitable for probabilistic analyses. This method accounts for the distribution of drift and R/E vulnerabilities of all the NHD+ catchments cropped to the CoI, which can then be represented by a simplified modeling process which avoids conducting individual exposure assessments for each catchment.
Chris M. Holmes, Paul Hendley, Amy M. Ritter, Dean A. Desmarteau. Waterborne Environmental Inc., Leesburg, VA 20175, United States, Phasera Ltd., Bracknell, Berkshire RG12 2JJ, United Kingdom
PostersIndustrial and Specialty Chemicals2014
Washoff Potential of Pyrethroid Products From External Building Materials and Driveway Concrete Under Indoor Simulated Rainfall Conditions
Two studies were conducted to investigate the washoff potential of pyrethroid residues arising from urban/residential use patterns. Using a laboratory research track sprayer and indoor rainfall simulator, commercially available pyrethroid products were applied to small concrete slabs at typical label rates and subjected to a one-hour 25mm simulated rainfall event. The first study examined washoff from 2 commercial formulations of the same active ingredient (AI) applied to a wide range of building materials including concrete, asphalt, wood, vinyl, stucco, and aluminum. The second study further investigated the effects of formulation on driveway concrete using 17 commercial products covering a wide range of formulations and a number of different active ingredients. Chemical analyses quantified the mass of active ingredients found in the washoff and results were expressed as percent of applied chemical washed off. The studies found textured surfaces demonstrated reduced mass washoff compared to smoother surfaces and that, while pyrethroid AI’s generally behaved similarly, different formulations could cause significant differences in washoff potential.
Jennifer R. Trask, Paul Hendley, Russell L. Jones, Christopher M Harbourt, Joseph R. Chepega, Megan Cox, Paul Miller. (1) Waterborne Environmental, Inc., Leesburg, VA 20175, United States, (2) Phasera Ltd., Bracknell, Berkshire RG12 2JJ, United Kingdom, (3) Bayer CropScience LP, Research Triangle Park, NC 27709, United States
Papers & ReportsAgriculture and Food, Crop Protection2014
Ecological Risk Assessment for Chlorpyrifos in Terrestrial and Aquatic Systems in the United States
Papers & ReportsWater/Wastewater Assessments2014
Developing a Foundation for Eco-Epidemiological Assessment of Aquatic Ecological Status Over Large Geographic Regions Utilizing Existing Data Resources and Models
Eco-epidemiological studies utilizing existing monitoring program data provide a cost-effective means to bridge the gap between the ecological status and chemical status of watersheds and to develop hypotheses of stressor attribution that can influence the design of higher-tier assessments and subsequent management. The present study describes the process of combining existing data and models to develop a robust starting point for eco-epidemiological analyses of watersheds over large geographic scales. Data resources from multiple federal and local agencies representing a range of biological, chemical, physical, toxicological, and other landscape factors across the state of Ohio, USA (2000–2007), were integrated with the National Hydrography Dataset Plus hydrologic model (US Environmental Protection Agency and US Geological Survey). A variety of variable reduction, selection, and optimization strategies were applied to develop eco-epidemiological data sets for fish and macroinvertebrate communities. The relative importance of landscape variables was compared across spatial scales (local catchment, watershed, near-stream) using conditional inference forests to determine the scales most relevant to variation in biological community condition. Conditional inference forest analysis applied to a holistic set of environmental variables yielded stressor–response hypotheses at the statewide and eco-regional levels. The analysis confirmed the dominant influence of state-level stressors such as physical habitat condition, while highlighting differences in predictive strength of other stressors based on ecoregional and land-use characteristics. This exercise lays the groundwork for subsequent work designed to move closer to causal inference. Environ Toxicol Chem 2014;33:1665–1677. © 2014 SETAC
Kapo, K. E., Holmes, C.M., Dyer, S. D., de Zwart, D. and Posthuma, L. (2014), Developing a foundation for eco-epidemiological assessment of aquatic ecological status over large geographic regions utilizing existing data resources and models. Environmental Toxicology and Chemistry, 33: 1665–1677. doi: 10.1002/etc.2557.