Document ID: EPA-HQ-OPP-2006-0239-0029
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2007-08-29T04:00Z

Docket Number:  EPA-HQ-OPP-2006-0239

www.regulations.gov

Fomesafen Final Work Plan (FWP)

For Registration Review

August 2007

 

Approved by:	 ___________________	

		Peter Caulkins, Acting Director

		Special Review and Reregistration Division

Date:

Docket Number:  EPA-HQ-OPP-2006-0239

www.regulations.gov

Introduction:

This is the Environmental Protection Agency’s (EPA’s) Final Work
Plan for the registration review of fomesafen.  This work plan includes
the expected registration review timeline.  The work plan also addresses
public comments received concerning the Preliminary Work Plan in the
Summary Document which was posted in the fomesafen registration review
docket, and any other comments concerning initial docket postings.  The
Summary Document provided information on what EPA knows about the
pesticide and what additional risk analyses and data or information the
Agency believes are needed to make a registration review decision.  

The Agency is implementing the new registration review program and plans
to review each registered pesticide every 15 years to determine whether
it continues to meet the Federal Insecticide Fungicide and Rodenticide
Act (FIFRA) standard for registration.  Changes in science, public
policy, and pesticide use practices will occur over time.  The
registration review program is intended to make sure that, as the
ability to assess risk evolves and as policies and practices change, all
registered pesticides continue to meet that statutory standard.  The
public phase of registration review begins when the initial docket is
opened for each case.  Information on this program is provided at:  
HYPERLINK "http://www.epa.gov/oppsrrd1/registration_review/_" 
http://www.epa.gov/oppsrrd1/registration_review/ 

Comments Received on Preliminary Work Plan:

EPA received comments during the public comment period on the initial
fomesafen docket.  However, these comments, which are addressed in this
document, did not change the data and risk assessment needs or the
timeline detailed in the Preliminary Work Plan.  This document makes
final the work plan for the fomesafen registration review process.  A
listing of the comments and responses are in the “Summary of Comments
and Agency Responses” section of this document.

Risk Assessment and Data Needs:

  

The Agency does not require any additional ecological effects or
environmental fate data to support the current assessments.  However,
the Agency will conduct an endangered species risk assessment for all
uses.  The Agency does not require any additional human health risk
assessments or related data.

Ecological Risk:

Ecological risk assessments for fomesafen uses were completed January
30, 2006 for use on soybeans, and for new uses of fomesafen on cotton,
snap beans, and dry beans. 

Docket Number:  EPA-HQ-OPP-2006-0239

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The planned ecological risk assessment will allow the Agency to
determine whether fomesafen use has "no effect" or "may affect"
federally listed threatened or endangered species (listed species) or
their designated critical habitat.  If the assessment indicates that
fomesafen "may affect" a listed species or its designated critical
habitat, the assessment will be refined.  The refined assessment will
allow the Agency to determine whether use of fomesafen is “likely to
adversely affect” the species or critical habitat or "not likely to
adversely affect" the species or critical habitat.  When an assessment
concludes that a pesticide's use "may affect" a listed species or its
designated critical habitat, the Agency will consult with the U.S. Fish
and Wildlife Service and National Marine Fisheries Service (Services),
as appropriate.

Human Health Risk:

The previously completed dietary assessments (2/28/06) that considered
dietary exposure to fomesafen from food and drinking water are adequate
and there is no dietary risk that exceeds the Agency’s level of
concern (LOC).  Thus, no additional data are needed.  

The occupational database is completed for the existing uses and the
latest risk assessment (2/28/06) indicates that most of the occupational
scenarios do not result in risk concerns, with the exception of
inhalation risk to mixer/loaders for aerial application.  The Agency is
working with the registrant to address this risk.

Docket Number:  EPA-HQ-OPP-2006-0239

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Timeline:

EPA has created the following estimated timeline for the completion of
the fomesafen registration review.  

Activities 	Estimated Month/Year

Phase 1: Opening the docket

Open Public Comment Period for Fomesafen Docket  	Mar. 2007

Close Public Comment Period 	June  2007

Phase 2:  Case Development

Develop Final Work Plan (FWP)	Aug. 2007

Open Public Comment Period for Preliminary Risk Assessments 	1st Quarter
2009

Close Public Comment Period	2nd Quarter 2009

Phase 3: Registration Review Decision

Open Public Comment Period for Proposed Reg. Review Decision 	3rd
Quarter 2009

Close Public Comment Period 	4th Quarter 2009

Final Decision and Begin Post-Decision Follow-up	1st Quarter 2010

Total (years)	3.0

Summary of Comments and Agency Responses:

  

The fomesafen registration review docket was opened for a 90-day comment
period beginning on March 28, 2007.  During that time, comments were
received from the technical registrant, Syngenta Crop Protection, the
FIFRA Endangered Species Task Force (FESTF), and New York State
Department of Environmental Conservation. 

Summary of Comments Regarding EPA Proposed Actions

1.	Comment:  Syngenta responded to EPA anticipating conducting an
endangered 	species risk assessment for all fomesafen uses.  Syngenta
indicated that they 	submitted an endangered species assessment for
fomesafen on March 27, 2006 	(MRID No. 46796201).  This submission was
made in support of the addition of 	Cotton, Dry and Snap Beans to the
Reflex Herbicide (EPA Reg.No.100-993) 	label.  The conclusion from this
risk assessment was that even using worst-case 	screening level risk
methodologies there will be no effect to threatened or 	endangered
terrestrial animals, aquatic animals, aquatic plants and monocot plant 
species from the use of fomesafen in cotton, dry beans, or snap beans. 
In addition 	fomesafen is not likely to adversely affect threatened or
endangered terrestrial 	dicot species or the habitat of listed species.

Docket Number:  EPA-HQ-OPP-2006-0239

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	Response:  The Agency thanks Syngenta Crop Protection for its comment,
and 	will consider this information as it conducts the registration
review and makes its 	registration review decision. 

2.	Comment: Syngenta responded to EPA’s recommendation for requiring a
		respirator to mitigate inhalation exposure risks.  Syngenta does not
agree with the 	occupational exposure assessment that leads to the
recommendation for requiring 	a respirator to mitigate inhalation
exposure risks.  The registrant feels that the 	toxicity endpoint
selected for the short-term inhalation exposure from the 90-day 	feeding
study is not appropriate because the short-term exposure is defined as 1
to 	30 days exposure duration.  A 90-day study covers a much longer
duration of 	exposure.  Syngenta suggests the use of a developmental
toxicity study in rats for 	selecting the short-term inhalation exposure
assessments.

	Response:  The liver appears to be a target organ in the rat for
fomesafen, since fomesafen has been shown to consistently affect the
liver in subchronic and chronic feeding studies in rats, as well as in
the rat reproduction study. Although it is logical for the registrant to
suggest selecting the toxicity endpoint for short-term inhalation
exposure based on a developmental toxicity study in terms of duration of
exposure, liver effects are not examined in a developmental toxicity
study. Additionally, some pesticides that produce liver toxicity
demonstrate liver effects with repeated dosing for a short duration (2
weeks to 30 days).  Therefore, in the absence of a shorter duration
(e.g., 30-day) feeding study on fomesafen to show otherwise, it is
assumed that fomesafen could cause liver toxicity following short-term
exposure.  Hence, for fomesafen, it is prudent to select the toxicity
endpoint for short-term inhalation exposure based on a 90-day feeding
study.  

3.	Comment:  Syngenta responded to EPA’s statement that additional
data has been 	previously required as a condition of registration for
certain new uses for 	fomesafen.  Syngenta 	indicated that the actions
required to satisfy these 	conditional registration requirements are
currently underway and will be 	completed within the required time
frame.

	Response:   The Agency thanks Syngenta Crop Protection for its comment.

Docket Number:  EPA-HQ-OPP-2006-0239

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Summary of Comments Regarding Toxicology Endpoints for Fomesafen

4.	Comment:  Syngenta responded to EPA’s use of a 90-day toxicity
study in rats to 	set a short-term toxicity endpoint (inhalation and
incidental oral).  Syngenta 	indicated that this is not appropriate,
because the duration of exposure is 3-fold 	greater than the maximum
definition of “short-term” exposure (1-30 days).  The 	liver effects
seen in this study at 100 ppm (10 mg/kg/day) were observed at the 
terminal sacrifice, after 90 days of exposure.  This included an
increased liver 	weight and increased alkaline phosphatase in males at
week 13, plus 	micropathology findings of hepatocyte eosinophilia and
reduce granulation 	(=hepatocyte hyalinization) in males and females at
week 13. The LOAEL 	findings quoted in the tables of Toxicology
Endpoints (EPA, 2006; EPA, 2007) 	inadvertently included increases in
alanine transaminase and aspartate 	transaminase as effects at 10
mg/kg/day, but 	in fact these were only increased at 	the high dose of
100 mg/kg/day (1000 ppm) in this study.  For short-term dermal 
toxicity, EPA has selected the rat developmental toxicity NOAEL of 100 
mg/kg/day, and this would be an appropriate endpoint for short-term
inhalation 	and oral exposures as well.  In support of this, there is no
evidence for an 	increased concern for exposures via the inhalation
route compared to other routes 	with fomesafen.  In an acute inhalation
study, fomesafen technical had an 	LC50>2.63 mg/L (Carter, 2004) placing
it in EPA Category IV.  Fomesafen 	is not volatile, and typical
agricultural applications of the final herbicide spray 	dilutions do not
produce particles of 	respirable size.  Therefore, the same study 	that
was used for short-term dermal toxicity risk assessment (rat development
	study) is equally applicable to short-term inhalation toxicity risk
assessment.

	Response:  The Agency thanks Syngenta Crop Protection for its comment,
and 	will consider this information as it conducts the registration
review and makes its 	registration review decision. 

Summary of Comments Regarding Environmental Exposure Characteristics for
Fomesafen

5.	Comment:  Syngenta noted that they have conducted an anaerobic
aquatic 	metabolism study that will be submitted to EPA to support the
current registration 	review 	(Peters, 2002).  The result of this study
was that fomesafen was found to 	degrade rapidly under anaerobic
conditions.  The degradation of fomesafen 	was studied using three US
water-sediment system and found to degrade with 	total system half-lives
ranging from 3.93 to 7.95 days.  Syngenta believes that 	

Docket Number:  EPA-HQ-OPP-2006-0239

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	the data from this study which indicated an upper 90% confidence limit
of 8.05 	days should be used as the anaerobic aquatic (benthic)
half-life input to 	PRIZM/EXAMS. 

	Response:  The Agency thanks Syngenta Crop Protection for its comment,
and 	will consider this information if submitted in a timely fashion as
it conducts the 	registration review and makes its registration review
decision. 

6.	Comments:  Syngenta noted that the equilibrium adsorption
coefficient, the 	lowest non-sand Kd value of 0.68 mL/g was used by the
EPA for PRZM/EXAMS 	modeling and Koc =68 mL/g was used for SCI-GROW,
using an assumed organic 	carbon comment of 1%.  Syngenta agrees with
this approach to the SCI-GROW 	input, since there is considerable
scatter in the Kd vs. %OC correlation.  	However, the input to 
PRZM/EXAMS that is normally used for this parameter is 	the average
Freundlich Kd or Koc.  In MRID 00259413, the adsorption of 	fomesafen to
each soil is represented as the mean Kd value, rather than the 
Freundlich coefficient. 

	Response:  The Agency thanks Syngenta Crop Protection for its comment,
and 	will consider this information as it conducts the registration
review and makes its 	registration review decision. 

7.	Comment:  Syngenta noted that the fomesafen soil accumulation was
modeled using the 90% confidence limit of the laboratory values for
half-life (428 days) with an assumption that aerobic soil metabolism is
the only degradation process.  Syngenta indicated that this approach
results in exaggerated predictions of fomesafen soil concentrations and
does not believe best estimates the potential for fomesafen residues to
accumulate in the soil.  Field dissipation studies conducted under
actual use conditions and that are cited by the Agency in the Ecological
Risk Assessment for use of Fomesafen on Cotton, Snap and Dry Beans
(Docket ID EPA-HQ-OPP-2006-0239-009) resulted in half-lives ranging from
50 to 150 days in surface soils.  The utilization of these points to
characterize the soil accumulation potential for fomesafen would result
in more appropriate estimates for use in modeling.  

	Response:  The Agency thanks Syngenta Crop Protection for its comment,
and 	will consider this information as it conducts the registration
review and makes its 	registration review decision. 

Docket Number:  EPA-HQ-OPP-2006-0239

www.regulations.gov

Summary of Comments Regarding the FIFRA Endangered Species Task Force

8.	Comment:  The FIFRA Endangered Species Task Force (FESTF) noted that
EPA 	stated in the Registration Review summary document that fomesafen
does not 	have a complete environmental risk assessment that is in
compliance with 	EPA’s 	Overview Document for Endangered and
Threatened Species Effects 	Determinations.  FESTF requests that EPA
assure that any company that is 	relying upon FESFT data, and are not a
member file a proper offer to pay for data 	compensation.

	Response:  The Agency thanks FESTF for its comment, and will consider
this 	information as it conducts the registration review and makes its
registration 	review decision. 

Summary of Comments Regarding the Aquatic Plant Risk Assessment

9.	Comment:  The New York State Department of Environmental Conservation
	(NYDEC) noted that the aquatic risk assessment appeared to be based on
the 	green algae, Selenastrum capricornutum, and did not report any
information for 	the macrophyte (Lemna gibba) study.  NYDEC also
commented that the active 	ingredient fomesafen is used in herbicides,
and therefore the macrophyte study 	is of great importance to
determining ecological risk from use of these products.  	The Department
requests that USEPA add the aquatic macrophyte acute 	toxicity test as
part of the Information Needs Section.  

Response:  The Agency thanks the New York State Department of
Environmental Conservation for its comment.  The Agency does have data
on the aquatic vascular plant, Lemna gibba, and this data shows that
Lemna gibba is less sensitive to fomesafen than Selenastrum
capricornutum.  However, the Agency will consider the Lemna gibba data
as it conducts the registration review and makes its registration review
decision.

Next Steps:

The Agency will conduct an endangered species risk assessment for all
uses of fomesafen.