AGENDA

FIFRA SCIENTIFIC ADVISORY PANEL (SAP)

	OPEN MEETING

	

December 1 – 3, 2009

FIFRA SAP WEB SITE http://www.epa.gov/scipoly/sap/

OPP Docket Telephone: (703) 305-5805

Docket Number: EPA-HQ- OPP-2009-0687

U.S. Environmental Protection Agency

Conference Center - Lobby Level

One Potomac Yard (South Bldg.)

2777 S. Crystal Drive, Arlington, VA 22202 

Scientific Issues Associated with Field Volatilization of Conventional
Pesticides

Please note that all times are approximate 

(See note at the end of the Agenda)

		Tuesday, December 1, 2009

9:00 A.M.	Opening of Meeting and Administrative Procedures by Designated
Federal Official – Sharlene Matten, Ph.D., Designated Federal
Official, Office of Science Coordination and Policy, EPA

9:05 A.M.	Introduction and Identification of Panel Members – 

		Kenneth Portier, Ph.D., Session Chair, FIFRA Scientific Advisory Panel

9:15 A.M.	Welcome and Opening Remarks – Steven Bradbury, Ph.D., Deputy
Director, Office of Pesticide Programs, EPA 

9:25 A.M.	Goals and Objectives – Tina Levine, Ph.D., Director, Health
Effects Division, Office of Pesticide Programs, EPA

9:35 A.M	Introduction: Assessment of Semi-Volatile Pesticides – Jeff
Evans, Health Effects Division, Office of Pesticide Programs, EPA 

10:10 A.M.	BREAK

10:25 A.M.	Overview of Available Pesticide Air Monitoring Data –
Charles Smith, Health Effects Division, Office of Pesticide Programs,
EPA 

11:10 A.M.	Exposure Estimation for Semi-Volatile Pesticides – Faruque
Khan, Ph.D, Chuck Peck, Gabe Rothman, Environmental Fate and Effects
Division, Office of Pesticide Programs, EPA

12:15 P.M.	LUNCH

1:30 P.M. 	Introduction: Hazard Assessment of Semi-Volatile Pesticides
– Judy Facey, Ph.D, Health Effects Division, Office of Pesticide
Programs, EPA

2:00 P.M.	Overview of Reference Concentration (RfC) Methodology –
Annie Jarabek, Ph.D, National Center for Environmental Assessment,
Office of Research and Development, EPA 

3:00 P.M.	BREAK

3:15 P.M.	Hazard Assessment of Semi-Volatile Pesticides – Elizabeth
Mendez, Ph.D, Health Effects Division, Office of Research and
Development, EPA

4:15 P.M.	Risk Assessment of Semi-Volatile Pesticides – Charles Smith,
Health Effects Division, Office of Pesticide Programs, EPA

5:30 P.M.	Adjourn

AGENDA

FIFRA SCIENTIFIC ADVISORY PANEL (SAP)

	OPEN MEETING

	

December 1 – 3, 2009

FIFRA SAP WEB SITE http://www.epa.gov/scipoly/sap/

OPP Docket Telephone: (703) 305-5805

Docket Number: EPA-HQ- OPP-2009-0687

U.S. Environmental Protection Agency

Conference Center - Lobby Level

One Potomac Yard (South Bldg.)

2777 S. Crystal Drive, Arlington, VA 22202 

Scientific Issues Associated with Field Volatilization of Conventional
Pesticides

Wednesday, December 2, 2009

9:00 A.M.	Opening of Meeting - Administrative Procedures by Designated
Federal Official - Sharlene Matten, Ph.D., Designated Federal Official,
Office of Science Coordination and Policy, EPA

9:05 A.M.	Introduction and Identification of Panel Members – Kenneth
Portier, Ph.D., Session Chair, FIFRA Scientific Advisory Panel 

9:10 A.M.	Follow-up from Previous Day’s Discussion – TBD, Health
Effects Division, Office of Pesticide Programs, EPA

9:30 A.M.	Public Comments

10:30 A.M. 	BREAK

10:45 A.M.   	Public Comments cont’d

12:00 P.M.	LUNCH

1:00 P.M.	Charge to the Panel – TOPIC A:  Exposure Assessment Issue

Traditionally, the Agency’s assessment of bystander inhalation
exposure to volatile pesticides has relied extensively on the use of air
monitoring data.  However, for the fumigants, an exposure assessment
methodology was developed that combined the use of air models and air
monitoring data.  The Agency has taken the exposure assessment
methodologies developed for the fumigants and further adapted them by
utilizing soil models to predict field volatilization of conventional
pesticides from plant and soil surfaces.  Based on this premise, the
Agency has identified several key factors for consideration by the
Panel.  They include the evaluation of the approaches and data sources
used in the tiered exposure estimation methodology and use of soil
models for predicting flux of conventional pesticides.  Specifically,
the Agency identified the following issues for the Panel to consider:

Tier I Approach for Identifying Volatile Chemicals of Concern for Risk
Assessment, Air Concentration. The Tier I approach incorporates the use
of vapor pressure alone to arrive at a saturated concentration in air. 
The estimated air concentration can be compared with available toxicity
data to evaluate inhalation exposure concerns to human and other
terrestrial organisms. 

Please comment on the Agency’s approach for using the Tier I air
concentration estimation method as a screening procedure.  Please
discuss the strengths and limitations of the screening approach.  Please
identify any alternative methods and/or physical-chemical properties, if
any, which may be utilized as a screening procedure to identify
chemicals with potential inhalation exposure concerns.

Tier II Approach for Identifying Volatile Chemicals of Concern for Risk
Assessment, Volatility and Flux Models.  Two options are being
considered to refine the Tier I estimation method. Option A incorporates
the use of physical-chemical properties including application rate,
vapor pressure, solubility, and Koc in an empirically-derived function
to estimate flux rates.  This option has less constraints and requires
fewer input parameters to generate flux rates as compared to Option B
described below. 

a. Given the state of the science, please comment on the applicability
of using the Option A model to predict flux rates.  Please discuss the
strengths and limitations of this approach and how these impact the
results.   Please identify any alternative methods, if any, which may be
utilized to identify chemicals with potential inhalation exposure
concerns.

Tier II, Option B is a refined process which utilizes fate and transport
models to predict flux rates of applied pesticides which off-gas from
treated fields.  Optimum fate and transport models consider mechanisms
related to volatilization, biodegradation, abiotic degradation,
physical-chemical properties, runoff, crop uptake, and leaching to
account for the transformation and movement of the entire initially
applied material.  Volatilization mechanisms from bare soil and crop
canopy surfaces are also important processes which the Agency believes
ought to be considered to fully account for volatilization and diffusion
from the vadose zone and canopy into the atmosphere.  The Agency has
utilized two models, the Pesticide Root Zone Model (PRZM) and the
Pesticide Emission Assessment at Regional and Local Scales (PEARL) which
incorporate these mechanisms and have the utility for the prediction of
flux rates from treated fields. Option B requires extensive knowledge on
environmental fate properties, as well as information related to
application site, crop management and meteorology. 

b. Please comment on the applicability of using fate and transport
models to predict flux rates given the state of the science.  Please
discuss the strengths and limitations of both models and how these
impact the results.  Please identify any fate and transport model(s)
which the Agency has not considered in this analysis which would be
applicable for pesticide applications and crop management scenarios.

3:00 P.M.	BREAK

3:15 P.M.	Charge to the Panel – TOPIC B:  Toxicological Assessment
Issues

As the Agency’s understanding of the state-of the science in
inhalation toxicology has evolved so has the Agency’s approach to
conducting inhalation hazard and risk assessments.  This evolution has
seen the Agency move from converting oral doses to inhalation
concentrations to using the RfC methodology and/or physiologically-based
pharmacokinetic (PBPK) models.  As OPP continues to work on refining the
risk assessment paradigm, the Agency is seeking the SAP’s input on a
number of key factors.  They include the use of oral toxicity studies
when inhalation studies are not available and the use of aerosol
inhalation toxicity studies to represent toxicity to vapors of the same
chemical.  Specifically, the Agency identified the following issues for
the Panel to consider:

The analysis conducted by the Agency indicates that, in general, oral
toxicity studies may not accurately represent the full spectrum of toxic
effects that may occur as a result of inhalation exposure.  The analysis
also indicates that - unless the same endpoints are identified through
both routes of exposure - oral toxicity studies frequently underestimate
toxicity by the inhalation route.  The Agency has not been able to
discern any patterns in this under/over estimation.  Please comment on
any potential patterns that the Agency has not identified.  

For a significant number of conventional pesticides, inhalation toxicity
studies are not available.  Please comment on the scientific strengths
and weaknesses of available approaches that may be used in the interim
to assess inhalation hazard in the absence of inhalation toxicity
studies.

For inhalation toxicity studies the test material is typically
aerosolized.  After volatilization, however, the Agency anticipates
exposures to vapors rather than the aerosolized particles.  Please
comment on the predictive capabilities of aerosol studies to identify
potential toxic effects and/or quantify the dose-response resulting from
exposure to vapors.  Is the Panel aware of any studies that
quantitatively compare inhalation toxicity after exposure to vapors and
aerosols?  In the absence of such data, can the Panel recommend an
approach to account for the potential differences between vapors and
aerosols?

5:30 P.M.	Adjourn

AGENDA

FIFRA SCIENTIFIC ADVISORY PANEL (SAP)

	OPEN MEETING

	

December 1 – 3, 2009

FIFRA SAP WEB SITE http://www.epa.gov/scipoly/sap/

OPP Docket Telephone: (703) 305-5805

Docket Number: EPA-HQ- OPP-2009-0687

U.S. Environmental Protection Agency

Conference Center - Lobby Level

One Potomac Yard (South Bldg.)

2777 S. Crystal Drive, Arlington, VA 22202 

Scientific Issues Associated with Field Volatilization of Conventional
Pesticides

Thursday, December 3, 2009

9:00 A.M.	Opening of Meeting - Administrative Procedures by Designated
Federal Official – Sharlene Matten, Ph.D., Designated Federal
Official, Office of Science Coordination and Policy, EPA

9:05 A.M.	Introduction and Identification of Panel Members – Kenneth
Portier, Ph.D., Session Chair, FIFRA Scientific Advisory Panel

9:10 A.M.	Follow-up from Previous Day’s Discussion – TBD, Health
Effects Division, Office of Pesticide Programs, EPA 

9:40 A.M.	Charge to the Panel – TOPIC C:  Risk Assessment Issues

The Agency discussed its methodology for combining the exposure
estimation methodologies and inhalation toxicological approaches to
estimate postapplication bystander inhalation risks resulting from field
volatilization of conventional pesticides.  In estimating
postapplication bystander inhalation risks, there a few principles that
should be followed: (1) It is important to properly match the duration
of the exposure with a proper toxicity study of comparable duration. 
(2) Both dissipation of air concentrations around a treated field as
well as when retreatment of the field may occur need to be considered. 
(3) Clearly define the uncertainties and limitations of this type of
assessment.  The Agency has identified the following issues for the
Panel to consider with respect to estimating postapplication bystander
inhalation risks:

Please comment on the strengths and limitations of the Agency’s use of
the empirical and modeled air concentrations in the provided risk
assessment case study.  Does the Panel agree that the postapplication
bystander inhalation risk estimate case study appropriately matches the
duration of the exposure with the proper toxicological study of the same
duration?  Please comment on the scientific strengths and weaknesses of
conclusions and characterization regarding the estimated risks presented
in the case study.

10:30A.M.	BREAK

10:45 A.M.  	Charge to Panel –Discussion cont’d (as needed)

12:00 P.M.	Adjourn

Please be advised that agenda times are approximate; when the discussion
for one topic is completed, discussions for the next topic will begin. 
For further information, please contact the Designated Federal Official
for this meeting, Dr. Sharlene Matten, via telephone: (202)-564-0130;
fax: (202) 564-8382; or email: matten.sharlene@epa.gov

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