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.
Papers & ReportsAgriculture and Food, Crop Protection, Water/Wastewater Assessments2014
Sensitivity Analysis of Individual Parameters for Synthetic Pyrethroid Exposure Assessments to Runoff, Erosion, and Drift Entry Routes for the PRZM and AGRO-2014 Models
This analysis focused on individual parameter sensitivity to identify pyrethroid variables that have the greatest impact on predicted runoff and erosion mass loadings from the PRZM model as well those expected to have a significant effect on the receiving water body concentrations predicted by the AGRO-2014 modeling system. This study showed the PRZM and AGRO-2014 models were highly sensitive to numerous individual parameters related to the amount of chemical applied to the field and drift onto the receiving water body, chemical field degradation parameters, factors that greatly influence the content of the edge-of-field runoff/erosion flows, and parameters related to pond geometry and water-sediment partitioning parameters. View chapter >
“Describing the Behavior and Effects of Pesticides in Urban and Agricultural Setting, Chapter 12: Sensitivity Analysis of Individual Parameters for Synthetic Pyrethroid Exposure Assessments to Runoff, Erosion, and Drift Entry Routes for the PRZM and AGRO-2014 Models.” (Desmarteau, D.A. and Ritter, A.M.) American Chemical Society, 2014. Electronic Publication.
Papers & ReportsCrop Protection2014
Major Transport Mechanisms of Pyrethroids in Residential Settings and Effects of Mitigation Measures
The major pathways for transport of pyrethroids were determined in runoff studies conducted at a full-scale test facility in
central California, USA. The 6 replicate house lots were typical of front lawns and house fronts of California residential developments and
consisted of stucco walls, garage doors, driveways, and residential lawn irrigation sprinkler systems. Each of the 6 lots also included a
rainfall simulator to generate artificial rainfall events. Different pyrethroids were applied to 5 surfaces—driveway, garage door and
adjacent walls, lawn, lawn perimeter (grass near the house walls), and house walls above grass. The volume of runoff water from each
house lot was measured, sampled, and analyzed to determine the amount of pyrethroid mass lost from each surface. Applications to 3 of the
house lots were made using the application practices typically used prior to recent label changes, and applications were made to the other 3
house lots according to the revised application procedures. Results from the house lots using the historic application procedures showed
that losses of the compounds applied to the driveway and garage door (including the adjacent walls) were 99.75% of total measured runoff
losses. The greatest losses were associated with significant rainfall events rather than lawn irrigation events. However, runoff losses were
40 times less using the revised application procedures recently specified on pyrethroid labels. Environ Toxicol Chem 2014;33:52–60.
# 2013 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC. This is an open
access article under the terms of the Creative Commons Attribution License, which permits use, distribution, and reproduction in any
medium, provided the original work is properly cited.
Davidson, P.C., Jones, R.L., Harbourt, C.M., Hendley, P., Goodwin, G.E. and Sliz, B.A. (2014), Major transport mechanisms of pyrethroids in residential settings and effects of mitigation measures. Environmental Toxicology and Chemistry, 33: 52–60. doi: 10.1002/etc.2411.
Papers & ReportsCrop Protection2014
Determining Critical Factors Controlling Off-Site Transport of Pyrethroids in the Urban Environment
Identifying critical factors that control the off-site transport of pyrethoids in the urban environment is critical to the safe and effective use of pyrethroids in the control of insects for home and business owners. This work uses a data mining approach to extract critical event variables from an urban study site that had been operational for a year (August, 2011 – August, 2012). Six applications occurred for four surfaces (driveway, garage door, grass perimeter, and house wall) and one application to the grass lawn following historic and revised practices. A Multivariate Adaptive Regression Spline (MARS) modeling approach was used to statistically model the percent of pyrethroid mass applied (percent washoff) from all surfaces. This approach yielded accurate models for all surfaces, with the driveway surface having the simplest model of percent washoff. The MARS modeling approach allows very dynamic changes in variables to represent complex behavior at the sites—integrating many variables to calculate percent washoff. For all surfaces, a near-post application period (around 14 days for all surfaces except the grass lawn, which had an extended multiple month period post application) controlled washoff particularly during low intensity lawn sprinkler events. During natural and simulated rainfall events, the dynamics of washoff included multiple types of characterizing runoff factors (from 10, 20, 30, and 60 min maximum runoff rates), the rainfall amounts, days since the previous application of a pyretheroid, among other factors. In addition, a number of other often minor factors were included by the MARS models for each surface for the calculation of percent washoff that warrant further investigation.
“Describing the Behavior and Effects of Pesticides in Urban and Agricultural Setting, Chapter 3: Determining Critical Factors Controlling Off-Site Transport of Pyrethroids in the Urban Environment.” (Miller, P.S., Andrus, J.M., Davidson, P.C., Jones, R.L., Harbourt, C.M. and Zhang, X.) American Chemical Society, 2014. Electronic Publication.
Papers & ReportsIndustrial and Specialty Chemicals2014
Washoff Of Cypermethrin Residues From Slabs of External Building Material Surfaces Using Simulated Rainfall
The use of pesticides by homeowners or pest-control operators in urban settings is common, yet contributions of washoff from these materials are not easily understood. In the present study, cypermethrin, formulated as Cynoff EC (emulsifiable concentrate) and Cynoff WP (wettable powder) insecticides, was applied at typical rates to 10 different building material surfaces to examine its washoff potential from each surface. Using an indoor rainfall simulator, a 1-h rainfall event was generated and washoff samples were collected from 3 replicates of each surface type. Washoff was analyzed for cypermethrin using gas chromatography-negative chemical ionization mass spectrometry. An analysis of variance for a split-plot design was performed. Many building materials had similar water runoff masses, but asphalt resulted in significantly reduced average water runoff masses (73% less). The Cynoff WP formulation generally produced greater cypermethrin washoff than the Cynoff EC formulation. In addition, results for both the WP and EC formulations indicated that smoother surfaces such as vinyl and aluminum siding had higher washoff (1.0–14.1% mean percentage of applied mass). Cypermethrin washoff from rough absorptive surfaces like concrete and stucco was lower and ranged from 0.1 to 1.3% and from 0 to 0.2%, respectively, mean percentage of applied mass. Both building material surface and formulation play a significant role in cypermethrin washoff.
Trask, J. R., Harbourt, C. M., Miller, P., Cox, M., Jones, R., Hendley, P. and Lam, C., Washoff of cypermethrin residues from slabs of external building material surfaces using simulated rainfall. Environ Toxicol Chem 2014;33:302–307. doi: 10.1002/etc.2432.