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.
Papers & ReportsAgriculture and Food, Crop Protection, Water/Wastewater Assessments2014
Influence of Landcover, Rainfall, and River Flow on the Concentration of Pyrethroids in the Lower American River, Sacramento, California, United States
A multi-site, spatio-temporal transect study on the Lower American River was conducted to systematically investigate the influence of agricultural and urban landcover, river flows and rainfall events on the concentration of pyrethroids. The majority of the flow in this section of the river throughout the year is controlled discharge from Folsom Dam. Local storm drains, small ephemeral channels and an extensive network of organized storm drain collection and pump stations discharge excess rainfall from surrounding urban and suburban environments into the Lower American River channel. Rainfall event-driven sampling was carried out during the 2011-2012 and 2012-2013 rainy seasons for eight pyrethroids. Results indicate that rainfall-runoff events are the driving perturbations behind the infrequent and highly variable pyrethroid movement into the Lower American River. A variety of factors contribute to environmental complexity. However, rainfall is the only true driver, while other land cover complexities, stormwater detention systems, and hard surfaces contribute to the variability in local rainfall-runoff contribution to river flows.
“Describing the Behavior and Effects of Pesticides in Urban and Agricultural Setting, Chapter 7: Influence of Landcover, Rainfall, and River Flow on the Concentration of Pyrethroids in the Lower American River, Sacramento, California, United States.” (Harbourt, C.M., Goodwin, G.E., Clark, S.L., Gantner, D., Sliz, B.A., Albertson, T., Dobbs, M., Henry, K. and Mitchell, G.) American Chemical Society, 2014. Electronic Publication.
The Need for More Realistic Aquatic Exposure Predictions: Opportunities for Improved Modeling Approaches
Current modeling approaches to assess drinking water and ecological risk from pesticides that are undergoing new registrations or re-registrations are conservative and designed to provide point estimates of risk. There are models currently available that provide flexibility to model actual drinking water watershed dynamics and incorporate spatial and agronomic variability. They are also fast, efficient, and may be used across a range of chemicals and geography. New tools being developed at USEPA (Surface Water Concentration Calculator and Spatial Aquatic Model) that may address some of the shortcomings of currently available modeling options. Waterborne employees presented their research and findings on this topic.
The Need for More Realistic Aquatic Exposure Predictions: Opportunities for Improved Modeling Approaches. Mike Winchell and Nathan Snyder. CropLife America/RISE Spring Conference, Crystal City, VA. April 9-11, 2014.
Pesticide Surface Water Monitoring: Bias Factors to Estimate Peak Concentrations and PRZM-Hybrid to Complete Measured Chemographs
Daily sampling for water quality monitoring at multiple sites is operationally challenging. Consequently, most monitored datasets do not have daily samples. We use bias factors (BFs) to address the following question: If less frequent monitoring datasets are used to estimate exposure, what is the probability or uncertainty of missing potential peak concentrations and/or maximum rolling average concentrations? Bias factors estimate the error in predicting the true peak concentration and/or maximum rolling average concentration from non-daily samples or sampling frequencies. We will present BFs calculated from two datasets representing multiple site-year-chemical combinations for selected sampling frequencies and relate them to watershed characteristics (hydrology, size). Calculated BF results will be compared to measured data for selected site-year-chemical combinations. We will also demonstrate how PRZM-Hybrid output can be used along with calculated BFs and less than daily monitoring data to estimate daily chemographs. This work demonstrates how lower frequency monitoring data can be coupled with model output to estimate potential maximum shorter duration concentrations to address water monitoring management needs.
Pesticide Surface Water Monitoring: Bias Factors to Estimate Peak Concentrations and PRZM-Hybrid to Complete Measured Chemographs. Wenlin Chen, Clint Truman, Paul Mosquin, Paul Miller and Mike Leggett. 9th National Monitoring Conference. Cincinnati, OH. April 28 – May 2, 2014.
Spatial Approaches to Refine Agricultural Chemical Use Areas for Endangered Species Assessments: Study With California Tiger Salamander
The geospatial analysis of a threatened and endangered species risk assessment will be presented by highlighting a tiered approach to characterizing the potential exposure of the California Tiger Salamander (CTS) to an herbicide use. The studied herbicide use was recorded in 35 California counties from 2001 to 2010 (Pesticide Use Reporting Database, California Department of Pesticide Regulation), while CTS critical habitats defined by the U.S. Fish and Wildlife Service were located in 21 counties. Using herbicide applications to orchards as an example for refining species/pesticide co-occurrence beyond the county-level screening, multiple approaches to characterizing spatial relationships between potential herbicide use sites and species habitats were performed. Best available geospatial data for species habitat, crop, vegetation, hydrology, wetlands, topography, and more were incorporated step-wise to represent realistic spatial relationships while documenting the impact (and uncertainty) each refinement made. Pesticide transport modeling was used to determine the distance that potential exposure may affect the species or its habitat. Refinements to this modeling further reduced the geographic extent of potential exposure. The tiered approach offers a step-wise refinement to quantify the potential overlap of pesticide usage with widely distributed species locations from the state-wide scale to the field scale. This was performed in a programmatic, documented and transparent way, allowing for full retrieval of all details.
Spatial approaches to refine agricultural chemical use areas for endangered species assessments: Study with California Tiger Salamander. Raghu Vamshi, Joshua Amos, Christopher Holmes, JiSu Bang. SETAC North America 34th Annual Meeting. Nashville, TN. November 17-21, 2013