Document ID: EPA-HQ-OPP-2002-0334-0006
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2007-09-20T04:00Z

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<p><strong>On this Page</strong></p>

<ul>
<li><a href="#attendees">Attendees</a></li>
<li><a href="#welcome">Welcome</a></li>
<li><a href="#action">Old Action Items</a></li>
<li><a href="#brief">Brief Updates</a></li>
<li><a href="#major">Major Topics</a></li>
<li><a href="#next">Next Meeting</a></li>
</ul>

<hr />

<h2 id="attendees">Attendees</h2>

<table class="table zebra" summary="Attendees">
<thead>
<tr><th scope="col">Name</th><th scope="col">Association</th></tr>
</thead>
<tbody>
<tr><td>Michael Barrett</td><td>OPP/EFED</td></tr>
<tr><td>Mark Carroll</td><td>UMD</td></tr>
<tr><td>Marietta Echeverria</td><td>OPP/EFED</td></tr>
<tr><td>Russell Jones</td><td>Bayer</td></tr>
<tr><td>Karen McCormack</td><td>OPP/EFED</td></tr>
<tr><td>Mark Shocken</td><td>Crompton</td></tr>
<tr><td>Jim Hetrick</td><td>OPP/EFED</td></tr>
<tr><td>Clive Wanner</td><td>Crompton</td></tr>
<tr><td>Dirk Young</td><td>OPP/EFED</td></tr>
<tr><td>Claude Beigel</td><td>BASF</td></tr>
<tr><td>Betsy Behl</td><td>OPP/EFED</td></tr>
<tr><td>Scott Jackson</td><td>BASF</td></tr>
<tr><td>R. David Jones</td><td>OPP/EFED</td></tr>
<tr><td>Paul Hendley</td><td>Syngenta</td></tr>
<tr><td>Richard Lee</td><td>OPP/EFED</td></tr>
<tr><td>Wenlin Chen</td><td>Syngenta</td></tr>
<tr><td>William Eckel</td><td>OPP/EFED</td></tr>
<tr><td>Louis Suarez</td><td>NERL/Athens</td></tr>
<tr><td>Ron Parker</td><td>OPP/EFED</td></tr>
<tr><td>Elise McCoy</td><td>FMC</td></tr>
<tr><td>Alex Clem</td><td>OPP/EFED</td></tr>
<tr><td>Susan Alexander</td><td>Stone Environ.</td></tr>
<tr><td>Jim Lin</td><td>OPP/EFED</td></tr>
<tr><td>Marty Williams</td><td>Waterborne</td></tr>
<tr><td>Nelson Thurman</td><td>OPP/EFED</td></tr>
<tr><td>Katherine Carr</td><td>Monsanto</td></tr>
<tr><td>Paul Horng</td><td>OPP/EFED & SRRD</td></tr>
<tr><td>Piyush Singh</td><td>DuPont</td></tr>
<tr><td>Adrian Wadley</td><td>WQC</td></tr>
<tr><td>Mary Nett</td><td>WQC</td></tr>
<tr><td>Don Wauchope</td><td>USDA/ARS</td></tr>
</tbody>
</table>

<p class="pagetop"><a href="#content">Top of page</a></p>
<hr />

<h2 id="welcome">WELCOME</h2>

<p>Michael Barrett opened the meeting at 9:00 and welcomed everyone.</p>

<p class="pagetop"><a href="#content">Top of page</a></p>
<hr />

<h2 id="action">OLD ACTION ITEMS</h2>

<ol>

<li><p>Update on prospective groundwater (PGW) guidance  - process for public posting is still in progress, formatting requirements may have to be made.</p></li>

<li><p>ORD to post latest PRZM version on Web site - done</p></li>

<li><p>Budgets and goals - to be discussed later in the meeting</p></li>

<li><p>EU kinetics group - EFED will send members - done</p></li>

<li><p>Don Wauchope to send USDA/ARS runoff data to Dirk Young - some progress.</p></li>

<li><p>Latest version of EXAMINER is with EPA - EXPRESS compatible - Ron Parker has
a copy but has not tested it yet</p></li>

<li><p>PLUS model - will be covered later in the meeting</p></li>

<li><p>EFED to resolve curve number switching - waiting input from PRZM developers</p></li>

<li><p>PGW database issues - will be covered later in the meeting</p></li>

<li><p>ORD coding problem for field capacity and wilting point - waiting for input from PRZM developers</p></li>

<li><p>USGS pesticide usage data - Gail Thelin/Bob Gilliom will be asked to discuss progress in developing usage data to support interpretation of monitoring data (and model development) at next EMWG meeting</p>
<p><strong>Action Item: Betsy/Mike to invite Gail and Bob to next meeting.</strong></p></li>

<li><p>PRZM-EXAMS scenarios - will be covered later in the meeting</p></li>

<li><p>Send turf runoff protocol to Betsy - done</p></li>

<li><p>Temperature-dependent PRZM code - will be covered later</p></li>

<li><p>Mark Russell's and Russell Jones' presentations on European modeling efforts posted to the Web site -  done</p></li>

<li><p>Don Wauchope's presentation posted to Web site </p>
<p><strong>Action Item:</strong>   Don to send his presentation on the USDA/ARS OPP/EFED workshop (focus on developing credible mitigation measures) ASAP</p></li>

</ol>

<p class="pagetop"><a href="#content">Top of page</a></p>
<hr />

<h2 id="brief">BRIEF UPDATES</h2>

<h3>European Union Activities - Russell Jones</h3>

<p>- reported that FOCUS exercises are going full tilt.  He is working on kinetics, but is not ready to report presently.  There will be a two-day FOCUS workshop for EPA people this week and a one-day seminar in RTP.  Groundwater models have not changed in the last six months, and they are working on the bugs in the surface water models.  All of these models will be posted on the Web site.</p>

<h3>USDA/ARS Mitigation Measures Workshop - Don Wauchope</h3>

<p>- reported that the draft final report of the workshop is being circulated for comment.  The report lists 4-5 priority research items. </p>

<h3>USDA/ARS Pesticide Properties  Database (New Version)</h3>

<p>This database will be listed under the Tifton watershed Web site in a month.  It combines USDA/ARS data with NRCS data and will for the time being be limited to six primary properties.  The new version will, like the previous version, include recommended values based on expert judgement.  IUPAC projects are being proposed to evaluate the physical chemical property values of pesticides - but will not cover soil sorption coefficients and degradation half-lives.  A suggestion was made that USDA coordinate with OECD since they may have useful input. </p> 

<h3>PRZM/EXAMS Update</h3>

<p>   - 3.12 final version will be on the CEAM Web site within two weeks.</p>

<h3>PRZM Temperature Correction - Wenlin Chen</h3>

<p>- discussed this problem regarding temperature-dependence of pesticide degradation which was mentioned at the last meeting.  PRZM 3.12 is not properly applying the temperature corrections for soil degradation.  PRZM 3.22, does not appear to have this problem.   There have been many questions over the years about how PRZM represents soil temperature.  Dave Jones suggested that inaccuracies in estimating soil temperature may be associated with imprecise estimation of soil albedo.</p>

<p><strong>Action Item: Mark Cheplick to post details of code changes in PRZM on this and slides showing impact of changes on the list server.</strong></p>

<h3>Rice Modeling - Jim Breithaupt</h3>

<p>- briefed the group on the rice model.  The rice scenarios seem to give reasonable results. Dean Pennington has developed useful GIS data for Mississippi rice agronomy and related flow information.  A new version of RICEWQ, which models parent and four metabolites runoff from rice fields, is available.  It can handle bi-phasic degradation and separate rate constants for water degradation processes (hydrolysis, metabolism, photolysis) and different soil/sediment degradation rates when flooded and not flooded.  It uses a standard stream and improves output format; the next version will be in a windows format and will include a thermal growth model for the rice crop.  Implementation work for Tier 1 rice scenarios will be supported in 2003, but the Tier 2 ones are at a lower priority.</p>

<h3>WARP Model - Ron Parker</h3>

<p>- expects to have a version of WARP available within a week which will predict the 9 percentiles of the distribution of atrazine at 5,000 watersheds defined by USGS GIS approaches; another 2000 CWS watersheds are still awaiting spatial verification.  Land use and soil information have been developed for each watershed.  A multi-compound version of WARP based on pesticide properties should be available soon.  Ron noted that funding for this project is not secure beyond this year, and they are looking for more funding.  The mini-pilot was conducted in order to determine sampling frequency.  This year they may look at six new sites to validate WARP predictions, and if more money is available, then go back to five original sites for additional sampling.</p>

<p>Sharing of watershed information may only occur after resolution of homeland security issues.  EPA Office of Water is looking at various security access levels as an option for data communication.  WARP may be a useful tool for selecting monitoring sites.</p>

<h3>EXPRESS Shell for PRZM-EXAMS - Ron Parker</h3>

<p>- is working on getting numbers for the model.  PCA's and tables and graphs were corrected.  Three versions of the model will be maintained on ORD's site: the beta version, new version, and European version.  Currently, EXPRESS results do not give the same answers as the stand-alone versions.  Currently, EFED is using the EFED shell "PE3" (originally developed by EFED to automate inputs and output presentation for single PRZM scenario runs) for routine risk assessments, and this will at some point be updated to "PE4".    PE4 provides presentation of calculations of instantaneous peak pesticide concentrations and will be made available to the public after the quality assurance procedures are completed.  More on PE3 and PE4 will be covered later in the meeting.</p>

<p><strong>Action Item:</strong> EFED will complete QA for PE3 and PE4 and post on Web site.</p>

<h3>Spray Drift Task Force - Norm Birchfield </h3>

<p>- reiterated EPA's concerns regarding restrictions on the use of and source code availability for AgDRIFT (see the December 2002 meeting minutes).  In response to EPA's concerns, the Task Force developed revised language that authorizes non-commercial use of the model, but problems still exist in the new language.  The new legal agreement states that anyone can use the model for screening level purposes, but at a higher level, only EPA can use it.  Any model used by EPA for regulatory purposes must be publicly available under the new Data Quality Guidelines.  Other modelers are reluctant to use AgDRIFT because of these problems, and tool development has been delayed.  Paul Hendley discussed the difficulty of reaching an agreement on the use of the model among all of the current model owners, right now they are awaiting a formal response from EPA to the latest changes in the AgDRIFT user license.</p>

<p><strong>Action Item:</strong> Norm Birchfield will respond to revised language proposed by SDTF.  This will also be an agenda item at the next meeting.</p>

<h3>EXAMINER</h3>

<p>New version of this tool for visualizing the model output data is available to EPA and is linked to EXPRESS.  Complete installation instructions will be provided on the EMWGlist website: 

<a href="https://lists.epa.gov/cgi-bin/lyris.pl?enter=emwglist&text_mode=&lang=english">
  https://lists.epa.gov/cgi-bin/lyris.pl?enter=emwglist&text_mode=&lang=english</a></p>

<p><strong>Action Item:</strong> All are asked to review this version of EXAMINER before next meeting. </p> 

<h3>PLUS</h3>

<p>This model was demonstrated at the last meeting and can be found in the public domain on the Waterborne Web site at:</p>

<p> <a href="http://www.waterborne-env.com/modeling/model_topic_develop.html">
  http://www.waterborne-env.com/modeling/model_topic_develop.html</a>
<a href="http://www.epa.gov/epahome/exitepa.htm" title="EPA's External Link Disclaimer"><img src="http://www.epa.gov/epafiles/images/epafiles_misc_exitepadisc.gif" width="87" height="13" alt="Exit EPA Disclaimer" /></a> </p>

<p><strong>Action Item:</strong> The developers want review from the regulatory community on the alpha version of PLUS and decide if it is a worthwhile project for further development.  The EFED Water Quality Tech Team will work with Scott Jackson to arrange a presentation at EPA to facilitate further discussion and review.</p>  

<p class="pagetop"><a href="#content">Top of page</a></p>
<hr />

<h2 id="major">MAJOR TOPICS</h2>

<h3>PRZM-EXAMS EFED Shell Update - Marietta Echeverria</h3>

<p>- an intern working with EFED for another month before transferring to the Office of Water for her next assignment, gave a demonstration of the EFED PRZM-EXAMS shell - PE4.  The shell generates input files, and the scenarios are external to the code.  The shell was originally developed to address needs for the organophosphate pesticide cumulative risk assessment. Current applications are for development of  the Refined Risk Assessment methods where speed is necessary.   EFED has been working on PRZM to make it run faster.  They have recompiled key PRZM processes in a FORTRAN environment and changed coding approaches from loops to array operations. They took ANEX and coupled it with the new PRZM version.  They have restructured the outputs, taken out redundant operations, and built in the variable volume pond.  The underlying algorithms have not been changed in PRZM, but some changes have been made in EXAMS.   The new shell calculates 4-day, 21-day, 60-day, and 90-day values in one second. </p>

<h3>Model QA/QC - Jim Hetrick</h3>

<p>- discussed OPP model QA/QC initiatives which includes:</p>

<ol>
<li><p>version control,</p></li>
<li><p>a library for archived model input/output files,</p></li>
<li><p>documentation of models, and</p></li>
<li><p>a systematic evaluation process of models.</p></li>
</ol>

<p>  The EFED evaluation process will involve both participation in the ORD model QA/QC process for models they provide (currently PRZM and EXAMS) and internal QA/QC for models developed within EFED and an interim EFED model process that is being used to evaluate the new PRZM shell (PE4.pl), using four dummy compounds and IR and pond versions of two scenarios (MN alfalfa and MS cotton).  EXPRESS may be included in the later evaluations. </p> 

<h3>Prospective Groundwater Database - Michael Barrett</h3>

<p>- gave an update on this database which will use a Microsoft ACCESS platform.  It includes site data for modeling, saves time for interim reports, and reduces data transfer errors.  Guidance for data reporting may include sample templates and reporting field characteristics.  The database will contain: agronomic data, pest application data, tracer application data, site monitoring data, soil profile data, and additional on-site soil data.  Historical weather data sets may be requested by EFED, if needed.  Next steps are to complete the field specs and develop the sample templates.</p>

<p><strong>Action Item:</strong> Send sample templates to registrants and post report update on the Web.</p>

<h3>EFED Water Quality Priorities for FY 2003 - Betsy Behl</h3>

<p>- outlined EFED's budget priorities for water quality in FY2003.  Resources will be focused on documenting accomplishments to date and on projects that promote risk assessment consistency and quality.  Increasing refinement of endangered species risk assessments is also an area that will be emphasized.  There is no money beyond mission support, and there is little external cash and internal manpower.  Project priorities for the water quality tech team related to environmental model development include:</p>

<ul>
<li><p>Tiering paper - documents refinements of risk assessment - more of a policy paper - Nelson Thurman has the lead.</p></li>
<li><p>QA/QC and model version control</p></li>
<li><p>Tier I Rice screening model will be developed this year; Tier II rice scenarios may be put on hold.</p></li>
<li><p>WARP refinement and related drinking water efforts are ongoing.</p></li>
<li><p>Groundwater projects - may have an evaluation of models this year using comparisons with results of selected prospective ground-water monitoring studies since cumulative risk assessment will require this.  Comparisons with some of the FOCUS models used in European risk assessments may be made,  Russell Jones says that these models tend to give similar answers.</p></li>
<li><p>Develop standard scenarios QA process for surface water modeling; respond to public comments and make changes.</p></li>
<li><p>Variable pond model needs to be completed.</p></li>
</ul>

<h3>Turf Thatch Modeling - Mark Carroll (University of Maryland)</h3>

<p>- presented thatch modeling studies that were conducted at the University of Maryland.  These studies are aimed at determining the effects of thatch on the transport of pesticides through the soil column and then comparing the results with model predictions.  The results of these studies showed that thatch did not significantly reduce leaching of pesticides (triclopyr, 2,4-D, and carbaryl).  He also found good agreement between actual lab data and model predictions.</p>

<p><strong>Action Item:</strong> Mark Carroll to send his overheads to Mike Barrett for posting on the list server.</p>

<h3>Runoff Studies for Turf - Mary Nett </h3>

<p>- summarized a draft field protocol for measuring turf runoff that could be used for refined risk assessments.  The protocol is being tested at three locations: OK, MD, and MS - somewhat different field design at each site.  The objective of the study is to provide support for standardized data collection parameters and to provide data to bridge to existing field data sets (e.g., US Golf Association data).  Mary needs feedback on this draft protocol and suggestions for improving the design.</p>

<p><strong>Action Item:</strong> Mary to send protocol details to Michael Barrett who will post on the list server for further debate and comment.</p>

<p>Issues brought up in the discussion included:</p>

<ul>
<li><p>Differences in features of residential turf, which is not addressed in this study.</p></li>
<li><p>Influence on pesticide fate of recently established turf may be significantly different than for aged turf.</p></li>
<li><p>Using identical simulated storms for each location versus storms tailored to be more representative of the local climate.</p></li>
<li><p>Importance of the intensity of the rainfall.</p></li>
<li><p>Debate over what pesticides to include.</p></li>
<li><p>Types of data need to support future model development.</p></li>
</ul>

<h3>Incorporating Full-Time Series Drinking Water EECs in Dietary Risk Assessments - Nelson Thurman</h3>

<p>- described the proposed changes in the way drinking water exposure estimates are incorporated into dietary risk assessments.  Instead of calculating a drinking water level of concern (DWLOC) using a single 1-in-10 year peak exposure estimate the full daily time series distribution generated by PRZM/EXAMS will be incorporated into the dietary risk assessments.   OPP currently uses DEEM-FCID (Dietary Exposure Evaluation Model) software to estimate exposures from food where exposure = consumption x residue.  DEEM produces an estimate of the distribution of exposures through food using probabilistic (Monte-Carlo) techniques.  Some issues with this that were brought up were:</p>

<ul>
<li><p>Pesticide concentrations in water often vary more significantly over the course of a year (with very distinctive seasonal patterns for many drinking water sources)</p></li>
<li><p>Pesticide residues tend to have a pronounced regional variation that is carried over into regional variation in exposure because most drinking water sources are locally derived.</p></li>
<li><p>People drink water every day usually from the same source, while food consumed by most individuals comes from multiple sources around the world.</p></li>
</ul>

<p>The drinking water level of comparison (DWLOC) is the theoretical concentration limit for a pesticide in drinking water, which when combined with exposure from food, would result in aggregate exposure just equal to the PAD (safe exposure).  A DWLOC is based on how much additional exposure through water would be acceptable once exposures in food have been estimated.  The DWLOC is  not a probabilistic approach; does not simultaneously evaluate food and water exposures and does not consider residential exposures.  DEEM/Calendex incorporates the concept of a Calendar to evaluate aggregate exposures.  It looks at each day of the year and allows appropriate "temporal matching" of exposure through food and drinking water (residential pathways, also).  The DEEM/Calendex approach was used in the OP cumulative approach because the Agency needed to reflect temporal co-occurrence of multiple chemicals in water and combine with residential exposures. </p>

<p>A major issue brought up in the discussion was on how to blend temporal distributions with population distributions - this may need to be brought together in a CARES/Calendex environment.  Many of these issues may be covered in a policy paper to be issued in 2003.  There are fundamental issues depending upon whether chronic or acute issues dominate the assessment.   A tiered scheme may be needed for drinking water assessments so that unnecessary work is not conducted.  For example, if a Tier 1 DWLOC approach can be passed, no further work may be needed.  Failing that, a worst case PRZM/EXAMS daily data set could be added into a CARES or Calendex type assessment with work ensuring that relevant water, dietary, and residential consumption predictions for specific use regions are considered together as a set of regionally specific assessments that might constitute the highest tier.  Questions were also asked about how the Agency would deal with ground water. </p> 

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<p>Betsy Behl will propose a date on the list server.  The second week in June looks good.</p>

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