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American Chemical Society's (ACS) Fall 2022 Meeting

Aug 21 - 25, 2022
Chicago, IL & Hybrid

The Stone-Intrinsik Team is proud to sponsor the American Chemical Society's (ACS) Fall 2022 Meeting, August 21-25, 2022. We hope you will join us in Chicago where we will be sharing insights from our recent work!


Unmanned Aerial Systems (a.k.a. Drones): Pesticide Spraying & Other Agricultural Applications


Environmental Fate, Transport & Modeling of Agriculturally-related Chemicals

SUNDAY, AUGUST 21ST | 8:00 A.M. - 12 P.M.; 5:30 - 5:55 P.M.; 2:00 - 6 P.M. (USA/CANADA CENTRAL) 


#3738619 - Comparison of Drift Deposition From a UAS Application Using Tracer Dye with Multiple Downwind Sampling Methodologies

MONDAY, AUGUST 22ND | 5:30 - 5:55 PM (USA/CANADA CENTRAL) | Oral-Hybrid

Aaron Rice, (Presenter) Ben Brayden, Rebecca Mitchell, John Hanzas, Brent Toth, Meghan Arpino, Stone Environmental, Inc.; Andrew Hewitt, The University of Queensland Faculty of Science; Bill Reynolds, Leading Edge Aerial Technologies; 

Understanding, quantifying, and benchmarking the drift profile of pesticide applications from UAS is an emerging need in the industry. In the fall of 2021 Stone Environmental in partnership with Andrew Hewitt, PhD. of the University of Queensland, Australia, and Bill Reynolds of Leading Edge Aerial Technologies, performed a drift trial to measure the downwind deposition profile of a UAS using a tracer dye. In anticipation of future studies requiring GLP standards we performed this study to approximate the requirements of a GLP study. A PV35X UAS, piloted by Bill Reynolds, made six applications with various combinations of TTI 11004 and XR 11003 nozzles, a boom height of 1.5 and 3 m, and a compact and wide boom configuration. Deposition samples were collected using four different media. Mylar card deposition samples were processed using a fluorometer to measure drift deposition. Horizontal Kromekote cards were used to measure drift deposition as a comparison methodology. Vertically mounted nylon strings and rotary impingers mounted with Kromekote cards were used to measure downwind flux. This presentation will compare the drift profiles for the various variable combinations and will discuss the merits and challenges for each sample collection media. This presentation will also compare the results of the UAS application to ground boom applications and traditional aerial applications. 

#3743832 - Off Target Drift Reduction Efficacy of Hooded Sprayers for Pre- and Post-Emergent Applications

TUESDAY, AUGUST 23RD | 2:55 - 3:20 PM (USA/CANADA CENTRAL) Oral-Hybrid

Laura Sisco, (Presenter); Ben Brayden, Brent Toth, Jacob Mitchell, John Hanzas, Rachel Lightfoot, Rebecca Mitchell, Stone Environmental, Inc.; Sara Whiting, Will Griese, Yaning Yang, Randall Ripperger, Drew Smith, Bayer CropScience LP; Dr. Naresh Pai, Daniel Dyer, Bayer CropScience AG

Reducing off-target spray drift is necessary for sustainable pesticide use in agriculture. Keeping applications on target can reduce buffer requirements, protect sensitive non-target species, and improve efficacy. Many drift reduction technologies (DRT) have been tested, including improved nozzle designs, tank mix adjuvants, and various sprayer modifications, many of which successfully reduce off-target spray drift. Few DRTs match the effectiveness of hooded sprayers, which act as a physical barrier to contain finer droplets and separate spray from exogenous forces that drive horizontal movement, such as wind and turbulence due to the forward momentum of the sprayer. In 2017, Stone Environmental and Bayer Crop Science conducted spray drift deposition studies on bare ground using a hooded sprayer with three different spray nozzles (TTI, AIXR, TT) at two wind speed ranges (<10 mph and >10 mph). Results from these studies demonstrate that downwind deposition is markedly less than the required buffer distance for the test substance. In 2021, additional studies were completed on post-emergent cotton and soybean fields to determine if similar off-target drift reduction could be achieved using hooded sprayers during over the top (OTT) crop applications when there is a higher boom height and greater potential for airflow to influence horizontal movement of spray droplets. Results from the OTT studies show off-target deposition at marginally further distances than in the bare ground study, but still markedly less than the required buffer distance. This presentation will focus on comparing hooded sprayer off-target drift deposition to that made with conventional ground spray boom equipment.

#3736282 - Quality Culture: Incorporating Quality Principles Across Your Organization

WEDNESDAY, AUGUST 24TH | 2:05 - 2:30 P.M. (USA/CANADA CENTRAL) | Oral-Hybrid

Jennifer Cypher (Presenter), Stone Environmental, Inc.

At many organizations, Quality is a function, a department, maybe even a single person tasked with "policing" others. By incorporating fundamental quality principles at all levels, an organization can ensure their deliverables are of high quality, reduce inefficiency caused by rework, and show their clients that their work is of the highest integrity. This presentation will focus on four fundamental quality principles--competency, documentation, data management, and equipment--and illustrate ways to build these concepts into standard business operations and functions. While special attention will be paid to satisfying Good Laboratory Practice requirements, these four quality principles exist across multiple quality systems including GMPs, GCPs, ISO 9001, and ISO 13485.

#3743018 - Higher Tier Refinements to Drinking Water Exposure Concentrations: a Cotton Herbicide Case Study

SUNDAY, AUGUST 21st | 8:30 - 8:55 AM (USA/CANADA CENTRAL) | Oral In-Person

Michael Winchell (Presenter), Sebastian Castro-Tanzi, Marco Propato, Stone Environmental, Inc.; Philip Branford, ADAMA France

The US EPA has long provided a prescribed approach to conducting drinking water exposure modeling as part of a screening level human health risk assessment. In situations where the screening level modeling indicated potential human health risks, approaches to refining the drinking water exposure modeling were often left to the registrants to put forth and were implemented on a case-by-case basis. Within the past two years, EPA has formalized a multi-tiered approach to conducting surface drinking water assessments. Refined surface drinking water exposure modeling represents a significant component to the higher tiers of this new framework. At Tier 3 of the framework, the exposure modeling scenarios simulated at Tier 2 are modified by considering typical use information (rates, application dates, application methods), percent cropped area (PCA), and percent crop treated (PCT). The PCA and PCT components of Tier 3 are derived using actual Community Water System (CWS) watershed boundaries, recent years of crop/land use spatial data layers derived from remote sensing data, and state-level pesticide usage information. While the formalization of this tiered approach has been highly valuable, the confidentiality of the CWS watershed boundaries and unavailability of this data outside of government authorities makes directly adopting the Tier 3 modeling approach by registrants and other non-government entities unattainable. An approach for applying the Tier 3 refinement principles with surrogate CWS watersheds was developed and applied to an herbicide with a cotton use pattern to demonstrate the levels of refinement achieved with the Tier 3 surface water modeling methods. This modeling showed that reductions in estimated drinking water concentrations (EDWCs) of more than 90% were likely in moving from a Tier 2 to a Tier 3 exposure assessment. An analogous tiered approach to groundwater exposure modeling does not yet exist, however the US EPA has recently provided guidance on appropriate situations for modifying the depth of subsurface degradation assumption in deriving groundwater EDWCs. Using the same cotton herbicide as an example, we will report on the effects of this new refinement on predicted groundwater concentrations, as well as what these higher tier drinking water refinements mean for human health risk assessment outcomes.

#3750143 - APEX Simulations to Evaluate Effectiveness of Field-Level Conservation Practices in Reducing Off-Field Pesticide Transport for a Stewardship Assessment Tool

MONDAY, AUGUST 22nd | 10:15 - 10:40 AM (USA/CANADA CENTRAL) | Oral-Hybrid

Jody Stryker, Ph.D. (Presenter), Michael Winchell, Bettina Miguez, Stone Environmental, Inc.; Lula Ghebremichael, Tony Burd, Syngenta Crop Protection

Agricultural conservation practices are commonly implemented in watersheds to reduce sediment and nutrient losses from agricultural lands and improve surface water quality. While the effectiveness of practices in reducing sediment and nutrient losses has been quantified by numerous multi-agency programs and peer-reviewed studies, similar standardized effectiveness measures and tools are yet to be fully implemented in evaluating benefits of such practices in reducing pesticide losses. The adoption of a stewardship evaluation approach similar to established approaches for nutrients will lead to a scientifically rigorous yet simple to apply methodology that documents how farmer actions can directly translate to quantifiable reductions in off-target pesticide transport and subsequent water quality improvements. We aim to develop a web-based tool capable of evaluating the impacts of field and farm-level practices on off-field pesticide transport to derive metrics for quantifying environmental stewardship. The tool will utilize the US Department of Agriculture (USDA) Agricultural Policy / Environmental eXtender Model (APEX), a well-established, physically-based model that predicts the short and long-term impacts of agronomic management decisions on environmental quality. This phase of tool development focused on designing the APEX pesticide transport modeling approach including determination of the necessary pesticide application inputs, cropping cycle input options, conservation/stewardship practice options, and how the off-target pesticide transport and reductions will be quantified. Model test scenarios were developed to evaluate model behavior and compare the predictions of off-site pesticide transport reductions with expected values from the peer-reviewed literature. A subset of simulations were set up to mirror standard regulatory PRZM scenarios and results compared across models. The long-term vision is that outputs from the web-based tool, relative pesticide load reductions estimated from conservation practice implementation, could be incorporated into the regulatory modeling framework to quantify the water quality improvements realized in the context of FIFRA registration decisions and endangered species effects determinations.

#3739562 - Simulation of Pesticide and Metabolite Concentrations Using Swat+ Landscape Routing and Conditional Management Applications

MONDAY, AUGUST 22nd | 8:30 - 8:55 AM (USA/CANADA CENTRAL) | Oral In-Person 

Hendrik Rathjens, Jens Kiesel, Bettina Miguez (Presenters), Michael Winchell, Stone Environmental, Inc.; Robin Sur, Bayer CropScience AG

The Soil and Water Assessment Tool (SWAT) has been an internationally leading model for predicting the fate and transport of non-point source agrochemicals at the watershed scale for nearly two decades. SWAT is a semi-distributed model based on a hydrologic response unit (HRU), a conceptual component that aggregates areas with similar landscape characteristics within a watershed, including land use and soils, to simplify the calculation of water fluxes, as well as sediment and chemical loading to a channel system. Strengths of SWAT for the simulation of agrochemicals include the comprehensive hydrologic model, channel routing and in-stream chemical transport processes, and extensive customization of agronomic management practices. A recently released enhanced version of SWAT, SWAT+, provides three main advantages over the historically used SWAT model for pesticide risks assessments of flowing waterbodies: (1) the ability to directly simulate metabolites, (2) flexible spatial representation of landscape features and their interactions, and (3) advanced agricultural management practices, including rule-based probabilistic pesticide applications. This research was conducted to evaluate SWAT+’ new features and to assess its ability to predict pesticide and metabolite concentrations. The evaluation was conducted based upon a comparison of the results from seven different model configurations with high-resolution monitoring data. The results showed that (1) SWAT+ is able to simulate the formation of degradate compounds and predict resulting concentrations in surface water, (2) an accurate representation of both surface and subsurface transport processes for pesticide exposure assessments is important, and (3) an appropriate degree of realism can be achieved with a rule-based probabilistic pesticide application schedule if information about the annual percent crop treated, a typical application rate, and a typical application window is available.

#3742815 - Probabilistic Pesticide Usage-Based Approach to Deriving Aquatic Exposure Distributions Used in Endangered Species Assessments

MONDAY, AUGUST 22nd | 9:20 - 9:45 AM (USA/CANADA CENTRAL) | Oral In-Person

Michael Winchell (Presenter), Hendrik Rathjens, Stone Environmental, Inc.; Sean McGee, Bayer US LLC

Current methods used by the US EPA for evaluating the potential effects of pesticides on aquatic species protected by the Endangered Species Act include a probabilistic assessment of exposure for each species. The approach, implemented through EPA’s Magnitude of Effects Tool (MAGtool), samples a probabilistic exposure distribution derived from multiple model simulations for a given use pattern that accounts for variability in pesticide application timing and surface runoff potential. The MAGtool’s approach for deriving a probabilistic exposure distribution does not account for the extent or likelihood of pesticide usage within an aquatic species range or critical habitat. This presentation will discuss a methodology to account explicitly for the impact of pesticide usage on exposure magnitude and likelihood when deriving a species-specific probability distribution of aquatic exposure used in the context of a MAGtool-based endangered species assessment. The methodology accounts for uncertainty in annual pesticide usage at the Crop Reporting District (CRD) level by sampling from five different usage years, each receiving equal probability. The uncertainty in pesticide application rates and area treated is accounted for by assuming both maximum annual application rates minimum recommended application rates according to the pesticide label. Because field-specific pesticide application location information is unavailable, we applied a probabilistic spatial sampling approach to derive multiple random realizations of the locations of pesticide usage within a CRD at a one square mile resolution. In this assessment, 25 use footprints were developed for each usage year and rate scenario, resulting in a total of 250 use footprints realizations, providing a robust set of spatial pesticide use scenarios. These use footprint scenarios were intersected with watersheds representing static and flowing water body habitats within each species range. These watersheds were then simulated using EPA’s regulatory modeling tools to derive comprehensive exposure distributions reflecting the variability and spatial uncertainty of pesticide usage locations across a broad spectrum of habitat locations. These exposure distributions could be used within the MAGtool’s current probabilistic assessment framework, providing a critically needed link between pesticide usage and the magnitude and likelihood of exposure for a species.

#3735211 - ESASeedPARAM: A Seed Treatment Model for Threatened and Endangered Bird Species in the United States

MONDAY, AUGUST 22nd | 10:40 - 11:05 AM (USA/CANADA CENTRAL) | Oral-in-person

Dwayne Moore (Presenter), Colleen Priest,  Intrinsik, Ltd.

Under the Endangered Species Act, the US Environmental Protection Agency (EPA) and the Services (National Marine Fisheries Service and Fish & Wildlife Service) are required to assess the potential risks of pesticides to threatened and endangered (listed) species. Currently, the EPA lacks a refined model to assess risks of pesticides applied as seed treatments to listed granivorous and omnivorous bird species. Based on a thorough review of the diets of listed bird species and their locations relative to crops where seed treatments could be used, we identified ten species that could be exposed to seed treatment pesticides. Other listed bird species do not consume seeds and/or do not forage in agricultural areas. Listed bird species have unique characteristics that profoundly impact exposure. Thus, we developed the ESASeedPARAM (Endangered Species Assessment Seed Treatment Probabilistic Avian Risk Assessment Model) to incorporate species-specific diets, body weights, population abundances, foraging behavior, and food ingestion rates. The model also incorporates information on availability of treated seeds over time, dissipation of seed residues following planting, metabolism, and elimination by birds during and following exposure. The ESASeedPARAM does not consider effects to available prey and habitats that may also lead to impacts to listed bird species (i.e., “indirect” effects). In this presentation, we describe a refined risk assessment conducted using the ESASeedPARAM for a case study pesticide, imidacloprid, used as a seed treatment in wheat and soybean.

#3754469 - Model Evaluation of Spray Drift from Unmanned Aerial System

MONDAY, AUGUST 22nd | 5:05 - 9:30 PM (USA/CANADA CENTRAL) | Oral-Hybrid

Zhenxu Tang, Bayer Crop Science; Michael Winchell, Stone Environmental Inc., (Presenters); Dr. Dan E. Martin, Ph.D., Brad Fritz, USDA Agricultural Research Service; Yaning Yang, Bayer CropScience LP

Recently, with the increased use and availability of unmanned aerial systems (UAS) in the US for application of agrochemical sprays, a better understanding of spray drift from these platforms has emerged as a particular area of interest from many stakeholders. The approaches to better understanding off-target spray drift from UAS are being addressed from both field study and modeling perspectives. Field studies are allowing direct measurement of spay drift deposition from UAS under a range of environmental and application conditions, and this data is necessary to validate mechanistic models under development for the simulation of these emerging types of applications. Field studies evaluated spray drift for varied droplet sizes from a UAS compared to ground application equipment. These field datasets were then used to evaluate the predictions of spray drift deposition from a recently developed mechanistic model to simulate UAS agrochemical sprays and compared with regulatory modeling results for traditional spray application platforms. The results of these comparisons will be presented along with field study results which demonstrate that best management practices, such as swath offset, are important in achieving targeted sprays and reducing off-target spray drift from UAS. Regulatory drift evaluation should also consider such BMPs to reflect field practices.


Connect with Us During the conference

Contact Ben Brayden or Mike Winchell to schedule a time to meet virtually with our team during the conference. 


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