AUGUST 24-25, 2004 Meeting Agenda

FINAL
August 13, 2004

FIFRA SCIENTIFIC ADVISORY PANEL (SAP)
OPEN MEETING
AUGUST 24-25, 2004
FIFRA SAP WEB SITE https://www.epa.gov/scipoly/sap/
OPP Docket Telephone: (703) 305-5805
Docket Number: OPP-2004-0240

TUESDAY, AUGUST 24, 2004
Holiday Inn - National Airport
2650 Jefferson Davis Highway
Arlington, VA 22202
Telephone: (703) 684-7200

Fumigant Bystander Exposure Model Review: Probalistic Exposure and Risk Model for Fumigants (PERFUM) Using Iodomethane as a Case Study

• 8:30 AM Introduction and Identification of Panel Members – Stephen M. Roberts, Ph.D. (FIFRA SAP Chair)
  
  
• 8:45 AM Administrative Procedures by Designated Federal Official - Ms. Myrta Christian
  
  
• 8:50 AM Opening Remark - Mr. Jim Jones (Director, Office of Pesticide Programs, EPA)
  
  
• 8:55 AM Introduction - Ms. Margaret Stasikowski (Director, Health Effects Division, Office of Pesticide Programs, EPA)
  
  
• 9:00 AM Goals and Objectives – Mr. Jeffrey Dawson (Health Effects Division, Office of Pesticide Programs, EPA)
  
  
• 9:15 AM Probabilistic Exposure and Risk Model for Fumigants (PERFUM) - Dr. Richard Reiss on behalf of the Arvesta Corporation
  
  
• 10:00 AM BREAK
  
  
• 10:15 AM P robabilistic Exposure and Risk Model for Fumigants (PERFUM) - Dr. Richard Reiss on behalf of the Arvesta Corporation
  
  
• 11:30 AM LUNCH
  
  
• 12:30 PM Public Comments
  
  
• 1:30 PM Questions to the Panel

  Critical Element 1: Documentation

  Question 1: The background information presented to the SAP panel by the PERFUM developers provides both user guidance and a technical overview of the system. Please comment on the detail and clarity of this document. Are the descriptions of the specific model components scientifically sound? Do the algorithms in the annotated code perform the functions as defined in this document? Please discuss any difficulties encountered with respect to loading the software and evaluating the system including the presented case study?

  Critical Element 2: System Design/Inputs

  Question 2: In Section 2.3: Development of the PERFUM Modeling System of the background document, a series of detailed individual processes and components included in PERFUM are presented. The key processes include (1) incorporation of ISCST3 into PERFUM, (2) probabilistic treatment of flux rates; and (3) development of a receptor grid. Please comment on these proposed processes, the nature of the components included in PERFUM and the data needed to generate an analysis using PERFUM? Are there any other potential critical sources of data or methodologies that should be considered?

• 3:00 PM BREAK
  
  
• 3:15 PM Questions to the Panel (continued)

  Question 3: The determination of appropriate flux/emission rates is critical to the proper use of the PERFUM model as these values define the source of fumigants in the air that can lead to exposures. Upon its review of how flux rates can be calculated, the Agency has identified a number of questions it would like the panel to consider. In PERFUM, flux rates were treated as a probabilistic variable with an uncertainty developed from the statistical bounds of the flux calculation. For each measurement period a standard error is generated that reflects the measurement uncertainty of the flux rate. PERFUM then perturbs the concentration estimates within each period by the standard error using Monte Carlo methods to simulate the uncertainty in the flux estimates. What, if any, refinements are needed for this process including the manner in which flux values were calculated for each monitoring period to generate the standard error estimates? How appropriate is it to use a flux/emission factor from a single monitoring study (or small number of studies) and apply it to different situations such as for the same crop in a different region of the country? Please comment on PERFUM’s capability to adequately consider multiple, linked application events as well as single source scenarios? Does PERFUM appropriately address situations where data are missing? In the back-calculation approach used for estimating emission rates, the regression of measured versus modeled values can be forced through the origin or not. Which approach does the panel prefer and what are the implications of each approach?

• 4:30PM ADJOURNMENT

FIFRA SCIENTIFIC ADVISORY PANEL (SAP)
OPEN MEETING
AUGUST 24 - 25, 2004
FIFRA SAP WEB SITE https://www.epa.gov/scipoly/sap/
OPP Docket Telephone: (703) 305-5805
Docket Number: OPP-2004-0240

WEDNESDAY, AUGUST 25, 2004
Holiday Inn - National Airport
2650 Jefferson Davis Highway
Arlington, VA 22202
Telephone: (703) 684-7200

Fumigant Bystander Exposure Model Review: Probalistic Exposure and Risk Model for Fumigants (PERFUM) Using Iodomethane as a Case Study

• 8:30 AM Introduction and Identification of Panel Members – Stephen M. Roberts, Ph.D. (FIFRA SAP Chair)
  
  
• 8:35 AM Administrative procedures by Designated Federal Official - Ms. Myrta Christian
  
  
• 8:40 AM Follow-up from Previous Day’s Discussion – Mr. Jeffrey Dawson (Health Effects Division, Office of Pesticide Programs, EPA)
  
  
• 9:00 AM Questions to the Panel (continued)

  Question 4: The integration of actual time-base meteorological data into ISCST3 is one of the key components that separates the PERFUM methodology from that being employed by the Agency in its current assessment. There are several potential sources of these data including the National Weather Service, Federal Aviation Administration, California Irrigation Management Information System (CIMIS), and the Florida Automated Weather Network (FAWN). The Agency is also aware that there are several approaches that can be used to process meteorological data and acknowledges that PERFUM used PCRAMMET which is a standard Agency tool for this purpose as well as other techniques in some cases (e.g., for the FAWN & CIMIS data). Various datasets from both California and Florida were used as the basis for the PERFUM case study. Please comment on the methods used to select monitoring station locations? What criteria should be used to identify meteorological regions for analysis and how should specific monitoring data be selected from within each region? Please comment on the manner that data from the selected various stations were processed? Data quality and uncertainty associated with these data vary with the source. Does the panel agree with the approaches used to characterize these factors? Anemometer sampling height has been identified as a concern by the Agency in preparation for this meeting. What are the potential impacts of using data collected with different anemometer heights in an analysis of this nature? Does PERFUM treat stability class inputs appropriately? Does PERFUM appropriately calculate bounding air concentration estimates by concurrently using upper-bound meteorological and emission/flux inputs?

• 10:30 AM BREAK
  
  
• 10:45 AM Questions to the Panel (continued)

  Question 5: The Agency model, ISCST3 is the basis for the PERFUM approach. This model has been peer reviewed and is commonly used for regulatory purposes by the Agency. PERFUM also uses other Agency systems such as PCRAMMET. Please recommend any parameters that should be altered to optimize the manner that they are used in PERFUM? Does the panel agree with the manner in which the receptor grid was developed, and if not, please provide suggestions for improving this approach?

  ISCST3, as integrated into PERFUM, was run assuming rural, flat terrain which would be typical of treated farm fields but might not be typical of surrounding residential areas. Does the panel concur with this approach? What are the implications of such an approach? What improvements can be made to this approach? ISCST3, as integrated into PERFUM, was run in regulatory mode which includes the use of the “calms” processing routine. Does the panel concur with this approach? If not, please suggest a suitable alternative?

• 12:00 AM LUNCH
  
  
• 1:00 PM Questions to the Panel (continued)

  Critical Element 3: Results

  Question 6: Soil fumigants can be used in different regions of country under different conditions and they can be applied with a variety of equipment. Please comment on whether the methodologies in PERFUM can be applied generically in order to assess a wide variety of fumigant uses? What considerations with regard to data needs and model inputs should be considered for such an effort?

  Question 7: Please comment on whether PERFUM adequately identifies and quantifies airborne concentrations of soil fumigants that have migrated from treated fields to sensitive receptors? The Agency is particularly concerned about air concentrations in the upper ends of the distribution. Are these results presented in a clear and concise manner that would allow for appropriate characterization of exposures that could occur at such levels? The PERFUM model calculates the concentration distributions both in all directions and for only the maximum concentration direction. Can the panel comment on how accurately the model approximates both of these distributions?

• 2:30 PM BREAK
  
  
• 2:45 PM Questions to the Panel (continued)

  Question 8: A sensitivity/uncertainty analysis has been conducted and is described in the PERFUM background document. What types, if any, of additional contribution/sensitivity analyses are recommended by the panel to be the most useful in making scientifically sound, regulatory decisions? What should be routinely reported as part of a PERFUM assessment with respect to inputs and outputs? Are there certain tables and graphs that should be reported? What types of further evaluation steps does the panel recommend for PERFUM?

• 3:30 PM ADJOURNMENT

Please be advised that agenda times are approximate. For further information, please contact the Designated Federal Official for this meeting, Ms. Myrta Christian, via telephone: (202) 564-8450; fax: (202) 564-8382; or email: christian.myrta@epa.gov