1
vxEPA
United States
Environmental Protection
Agency	
                   Prevention, Pesticides
                   And Toxic Substances
                   (7508W)	
EPA738-R-02-010
July 2002
Interim Reregistration
Eligibility Decision (IRED)

DISULFOTON

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                United States
                Environmental Protection
                Agency
Prevention, Pesticides
and Toxic Substances
(7508C)
EPA 738-F-02-009
July 2002
               Disulfoton  Facts
         EPA has assessed the risks of disulfoton and reached an Interim Reregistration Eligibility
  Decision (TRED) for this organophosphate (OP) pesticide. Provided that risk mitigation measures are
  adopted, disulfoton's individual, aggregate risks are within acceptable levels.  Disulfoton is also
  eligible for reregistration, once cumulative risks are considered.
        EPA's next step is to consider the cumulative
 risks of the OP pesticides, which share a common
 mechanism of toxicity. The interim decision on
 disulfoton will not be final until these cumulative
 risks also are considered. Further risk mitigation
 may be warranted at that time.

        Used on a variety of crops, disulfoton
 residues in food do not pose a risk concern. Drinking
 water risk estimates suggest concern for potential
 surface water exposure. However, these are
 conservative estimates based on screening level
 models. Because of the conservative nature of these
 estimates and because of some uncertainties in the
 water assessment, the Agency believes that drinking
 water risks are likely to be lower than the current
 modeled estimates, and not of concern. Therefore, to
 address the potential concern for drinking water,
 EPA is requiring confirmatory environmental fate
 data and surface water monitoring data for disulfoton
 and its degradates.  Disulfoton's residential use as an
 insecticide for use on ornamental flowers and
 shrubs, including rose bushes, and outdoor potted
 plants  poses risk concerns to residential handlers for
 a few scenarios.  To address the scenarios of risk
 concern, the registrant has agreed to the following                	
 mitigation measures: limiting maximum application
 rate, prohibiting application with certain hand held devices, such as belly grinders, changes in
packaging, including a requirement for child-resistant packaging, and deletion of certain uses
including all indoor uses and use in home vegetable gardens.  With this mitigation limiting exposure
through household use, disulfoton fits into its own "risk cup" and does not pose aggregate risk
           The OP Pilot Public Participation Procss

               The organophosphates (OPs) are a group
        of related pesticides that affect the functioning of
        the nervous system.  They are among EPA's
        highest priority for review in implementing
        provisions of the Food Quality Protection Act
        (FQPA)of1996.
               EPA encourages the public to participate
        in the review of the OP pesticides. Through a six-
        phased pilot public participation process,  the
        Agency has released for review and comment its
        preliminary and revised scientific risk assessments
        for individual OPs.  (Please contact the OP
        Docket, telephone 703-305-5805, or see EPA's
        web site, www.epa.gov/pesticides/op.)
               EPA is exchanging information with
        stakeholders and the public about the OPs, their
        uses, and risks through Technical Briefings,
        stakeholder meetings, and other fora.  USDA is
        coordinating input from growers and other OP
        pesticide users.
               Based on current information from
        interested stakeholders and the public, EPA is
        making  interim risk management decisions for
        individual OP pesticides.  The Agency will make
        final decisions after considering the cumulative
        risks of the OPs.  (Please see
        www.epa.aov/Desticides/cumulative.htm)

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concerns. Other mitigation measures are necessary to address worker and ecological risks for
disulfoton, which are of concern. To mitigate worker risk, EPA is requiring closed mixing/loading
systems for liquid formulations; closed loading and transfer for granular formulations; enclosed cabs
plus a dust-mist respirator for all handlers using ground application equipment; enclosed cockpits and
mechanical flaggers for aerial application; maximum personal protective equipment where closed
cabs are not feasible; and increased re-entry intervals for foliar application to certain crops. To
mitigate ecological risks, EPA is requiring reduced number-of applications allowed per year; reduced
maximum rates;  phase out of certain uses; a 25-foot vegetative buffer between treated fields and
permanent water bodies; and a precautionary bee statement on labels. These measures substantially
reduce but do not fully mitigate worker and ecological risks.  However, EPA believes that the
benefits of continued disulfoton use on certain commodities outweigh the worker and ecological risk.
For other commodities where benefits do not outweigh the risk, use will be phased out by June 2004.

       EPA is reviewing the OP pesticides to determine .whether they meet current health and safety
standards. Older OPs require decisions about their eligibility for reregistration under FIFRA. OPs
with food, drinking water, residential, and any other non-occupational exposures must be reassessed to
make sure they meet the new FFDCA safety standard, effected by the Food Quality Protection Act
(FQPA)ofl996.

       The disulfoton interim decision was made through the OP pilot public participation process,
which increases transparency and maximizes stakeholder involvement in EPA's development of risk
assessments and risk management decisions.  EPA worked extensively with affected parties to reach
the decisions presented in this interim decision document.

Next Steps
                                                 «*;*%••:• ?*_*»
 1.     Numerous opportunities for public comment were offered as this decision was being
       developed. However, because some uses are being phased out, the disulfoton IRED is issued
       with a 30-day public comment period. (Please see www.epagov/pesticides/reregistration/
        status.htm or www.epa.gov/pesticides/op.

 2.      When EPA has considered the cumulative risks of the OP pesticides, the Agency will issue its
        final tolerance reassessment decision for disulfoton and may request further risk mitigation
        measures.  The Agency will revoke 33 tolerances now, because there is either no registered
        use or because the technical registrant has requested, and EPA has approved, voluntary
        cancellation of use on the commodities associated with these tolerances. Two tolerances for
        disulfoton will be lowered now, and several tolerances will be modified to correct
        commodity definitions. No tolerances will be raised and no new tolerances will be established
        until cumulative risks have been considered for all the OPs.

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               UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                                  WASHINGTON, B.C.  20460
                                                                               OFFICE OF
                                                                         PREVENTION, PESTICIDES
                                                                         AND TOXIC SUBSTANCES
  CERTIFIED MATT.
  Dear Registrant:
                                             i 11 H  3% A n,&f
                                                   31) .ml
        This is to inform you that the Environmental Protection Agency (hereafter referred to as
  EPA or the Agency) has completed its review of the available data and public comments
  received related to the preliminary and revised risk assessments for the organophosphate
  pesticide disulfoton. The public comment period on the revised risk assessment phase of the
  reregistration process is closed.  Based on comments received during the public comment period
  and additional data received from the registrant, the Agency revised the human health and
  environmental effects risk assessments and made them available to the public on March 10
  2000. Additionally, the Agency held a Technical Briefing on February 3, 2000, where the '
  results of the revised human health and environmental effects risk assessments were presented to
  the general public. This Technical Briefing concluded Phase 4 of the OP Public Participation
  Pilot Process developed by the Tolerance Reassessment Advisory Committee (TRAC)  and
 initiated Phase 5 of that process. During Phase 5, all interested parties were invited to participate
 and provide comments and suggestions on ways the Agency might mitigate the estimated risks
 presented in the revised risk assessments. This public participation and comment period
 officially commenced on March 10, 2000 and closed on May 9, 2000  due to unanticipated delavs
 in posting to the Agency's web site.

       Based on its review, EPA has identified risk mitigation measures that the Agency
 believes are necessary to address the human health and environmental risks associated with the
 current use of disulfoton.  The EPA is now publishing its interim decision on the reregistration
 eligibility of and risk management decision for the current uses of disulfoton and its associated
 human health and environmental risks. The reregistration eligibility and tolerance reassessment
 decisions for disulfoton will be finalized once the cumulative risks for all of the organophosphate
 pesticides are considered.  The enclosed "Interim Reregistration Eligibility Decision for  '
 Disulfoton," which was approved on March 29, 2002, contains the Agency's decision on the
 individual chemical; disulfoton. The Agency has decided to provide a  final 30-day opportunity
 for stakeholders to respond to the disulfoton interim risk management  decision. On March 26
 2002, the Agency was informed of other information that may be used to refine post-application
 risks and will address this issue during this comment period.  If substantive data or similar
 comments are received and indicate that any of the Agency's assumptions need to be refined and
 that alternate risk mitigation is warranted, appropriate modifications will be made at that time.

      A Notice of Availability for this interim reregistration eligibility decision (IRED)
document for disulfoton is being published in the Federal Register.  To obtain a copy of the

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      document, please contact the OPP Public Regulatory Docket (7502C , US EPA Ariel
  oBuSg  1200 Pennsylvania Avenue NW, Washington, DC 20460, tekphone (703) 305-
?805  SeXc copies of the IRED and all supporting documents are available on the Internet
at the following address: http:www.epa ony/pesticides/op.

       The IRED is based on the updated technical information found in the disulfoton public
docket  Thedocke not only includes background information and comments on the Agency s
 growers.

        This document and the process used to develop it are the result of a pilot process to






  stSolder advisory body that advised the Agency on implementing the new provisions of the
  ?QPA  Tie re^gislation and tolerance reassessment reviews for the organophosphate
  pesticides are following this new process.

         Please note that the disulfoton risk assessment and the attached IRED document concern
  only this pScuiar organophosphate. This IRED presents the Agency s conclusions on the
                                                                                      •
  mtasuTes necessary to address those human health and environmental risks associated with *e
                                                                                    >*
         uses of dlfoton.  The Agency will issue the final tolerance
   Sbton and finale decisions on registration eligibility once the cumulative risks for all of
   the organophosphates are considered.

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       This document contains both generic and product-specific Data Call-Ins (DCIs) that
outlines further data requirements for this chemical.  Note that a complete DCI, with all pertinent
instructions, is being sent to registrants under separate cover. Additionally, for product-specific
DCIs, the first set of required responses to is due 90 days from the receipt of the DCI letter.  The
second set of required responses is due eight months from the date of the DCI.

       As part of the IRED, the Agency has determined that disulfoton will be eligible for
reregistration provided that all the conditions identified in this document are satisfied, including
implementation of the risk mitigation measures outlined in Section IV of the document. The
Agency believes that current uses of disulfoton may pose unreasonable adverse effects to human
health and the environment, and that such effects can be mitigated with the risk mitigation
measures identified in this IRED document. Accordingly, the Agency recommends that
registrants implement these risk mitigation measures immediately. Sections IV and V of this
IRED document describe labeling amendments for end-use products and data requirements
necessary to implement these mitigation measures. Instructions for registrants on submitting the
revised labeling can be found in the set of instructions for product-specific data that accompanies
this document.

       Should a registrant fail to implement any of the risk mitigation measures outlined in this
document, the Agency will continue to have concerns about the risks posed by disulfoton.  Where
the Agency has identified any unreasonable adverse effect to human health and the environment,
the Agency may at any time initiate appropriate regulatory action to address this concern.  At that
time, any affected person(s) may challenge the Agency's action.

       If you have questions on this document or the label changes necessary for reregistration,
please contact the Chemical Review Manager, Christina Scheltema at (703) 308-2201.  For
questions about product reregistration and/or the Product DCI that accompanies this document,
please contact Jane Mitchell at (703) 308-8061.
                                         Sincerely,
                                         Lois A. Rossi, Director
                                         Special Review and
                                          Reregistration Division
Attachment

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INTERIM REREGISTRATION ELIGIBILITY




              DECISION




                 for




            BISULFOTON






               LIST A




             CASE 0102

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                              TABLE OF CONTENTS

 DISULFOTONTEAM  ....
                                      	•	iv
 GLOSSARY OF TERMS AND ABBREVIATIONS
                                               	v
 EXECUTIVE SUMMARY . .
                                   	 vii
 I.     Introduction	
                        	1
 II.    Chemical Overview
       A.     Regulatory History .;	      ••••••	3
       B.     Chemical Identification	• 3
       C.     Use Profile	3
       D.    Estimated Usage of Disulfoton	  	'	"4

HI.   Summary of Disulfoton Risk Assessment
      A.    Human Health Risk Assessment............    	•.... 8
            1.     Dietary Risk from Food	  	9
                  a.     Toxicity	   	" '	10
                  b.     FQPA Safety Factor	10
                  c.     Population Adjusted Dose (PAD) ....'..	!?
                  d.     Exposure Assumptions  		 11
                  e.     Acute Dietary (Food) Risk	'   .\
                  f.     Chronic Dietary (Food) Risk.	^
           2.     Dietary Risk from Drinking Water
                 a.     Surface Water		13
                 b.     Ground Water	       	14
           3.    Residential and Occupational Risk	?6
                 a.    Toxicity	    	18
                 b.    Residential Risk Assessment	^
                 c.     Aggregate Risk		   	20
                 d.     Occupational Risk Assessment	  	" ' ^A
                 e.     Incident Reports	           	
     B.    Environmental Risk Assessment .........  	40
           1.     Environmental Fate and Transport	'"^°
           2.     Ecological Risk Assessment		
                 a.     Ecological Hazard Profile	1!
                 b.     Risk to Birds and Mammals  .	^
                 c-     Risk to Insects	  	"	  3
                 d.     Risk to Aquatic Animals	Jf4
                e.      Risk to Plants	'""	44
                f.      Risks to Endangered Species	'" ^
                g.     Ecological Incident Reports	40

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                                                         	49
    C.    Alternatives and Benefits 	  	49
          1.    Alternatives	51
          2.    Benefits	



    B.    Summary of Phase 5 Comments	 • •	61
    C.    Regulatory Position	   	61
           1     FQPA Assessment	          61
                 a.     "Risk Cup" Determination	.'..... 62
                 b.     Tolerance Summary	   69
                 c.     Endocrine Disruptor Effects	 69
     D     Regulatory Rationale	•	       	69
           1.    Human Health Risk Mitigation                         	69
                 a     Dietary Mitigation	      72
                 b.    Homeowner Risk Mitigation                            ?4
                 c.    Aggregate Risk Mitigation  	?6
                 d.     Occupational Risk Mitigation	•	•'  ?9
            2.    Environmental Risk Mitigation	  82
            3.     Crop-Specific Decisions	 98
      E.    Labeling 	•	'	         	98
            1.     Endangered Species Statement	•	   	98
            2     Spray Drift Management 	       101
      F.    Disulfoton Risk Mitigation Summary  	r  '
                                                            	105
V     What Registrants Need to Do	105
      A.    Data Call-In Responses	•	     	106
      B!    Manufacturing-Use Products	108
      C.    End-Use Products	    	108
      D.     Existing Stocks	• •	   	108
      E     Labeling Changes Summary Table 	
                                                          	121
 VI. APPENDICES	

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     Office of Pesticide Programs:
                                    WSULFOTON TEAM
     David Anderson
     Richard Griffin
     Christina Jarvis
    Alan Nielsen
    JohnPunzi
    Shanna Recore


   Henry Craven
   John Jordan
   James Wolf
   Anne Stavola
   Larry Turner
   Henry Craven
  Colwell Cook
  Anthony Gilbert
  Nikhil Mallampalli
  Istanbul Yusef

 Registration Support-

 William Sproat
 George LaRocca
Christina Scheltema
Michael Goodis
                                        IV

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 GLOSSARY OF TERMS AND ABBREVIATIONS
 a.i.            Active ingredient
 aPAD         Acute Population Adjusted Dose
 AR           Anticipated Residue
 BCF          Bioconcentration Factor
 CDPR         California Department of Pesticide Regulation
 cPAD         Chronic Population Adjusted Dose
 CSF          Confidential Statement of Formula
 CFR          Code of Federal Regulations
 CSFII         USDA Continuing Surveys for Food Intake by Individuals
 DCI           Data Call-In
 DEEM         Dietary Exposure Evaluation Model
 DFR          Dislodgeable Foliar Residue
 DWEC         Drinking Water Estimated Concentration
 DWLOC       Drinking Water Level of Comparison
 EC            Emulsifiable Concentrate Formulation
 EEC          Estimated Environmental Concentration. The estimated pesticide concentration in an
               environment, such as a terrestrial ecosystem.
 EP            End-Use Product
 EPA          U.S. Environmental Protection Agency
 FDA          Food and Drug Administration
 FIFRA         Federal Insecticide, Fungicide, and Rodenticide Act
 FFDCA        Federal Food, Drug, and Cosmetic Act
 FQPA         Food Quality Protection Act
 FOB          Functional Observation Battery
 G             Granular Formulation
 GENEEC      Tier I! Surface Water Computer Model
 GLN          Guideline Number
 HDT          Highest Dose Tested
 IPM           Integrated Pest Management
 IR            Index Reservoir
 IRED          Interim Reregistration Eligibility Decision
 LC50          Median Lethal Concentration. Statistically derived concentration of a substance expected
               to causing death in 50% of test animals, usually expressed as the weight of substance per
               weight or volume of water, air or feed, e.g., mg/1, mg/kg or ppm.
 LD50          Median Lethal Dose. Statistically derived single dose causing death in 50% of the test
               animals when administered by the route indicated (oral, dermal, inhalation), expressed as
               a weight of substance per unit weight of animal, e.g., mg/kg.
 LOAEL        Lowest Observed Adverse Effect Level
 LOG          Level of Concern
 LOD          Limit of Detection
 LOQ          Limit of Quantitation
mg/kg/day      Milligram Per Kilogram Per Day
mg/L          Milligrams Per Liter
MOE          Margin of Exposure
MP           Manufacturing-Use Product
MRID         Master Record Identification (number). EPA's system of recording and tracking studies

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              submitted.
N/A          Not Applicable
NASS         National Agricultural Statistical Service
NAWQA      USGS National Water Quality Assessment
NOEC        No Observable Effect Concentration
NOAEL       No Observed Adverse Effect Level
OP           Organophosphate
OPP          EPA Office of Pesticide Programs
PAD          Population Adjusted Dose
PAM         Pesticide Analytical Method
PCA          Percent Crop Area
PDP          USDA Pesticide Data Program
PHED        Pesticide Handler's Exposure Data
PHI          Preharvest Interval
ppb          Parts Per Billion
PPE          Personal Protective Equipment
ppm          Parts Per Million
PRN          Pesticide Registration Notice
PRZM/
EXAMS       Tier II Surface Water Computer Model
RAC          Raw Agriculture Commodity
RBC          Red Blood Cell
RED          Reregistration Eligibility Decision
REI          Restricted Entry Interval
RfD          Reference Dose
RQ          Risk Quotient
RUP          Restricted Use Pesticide
SCI-GROW   Tier I Ground Water Computer Model
SF           Safety Factor
SLN          Special Local Need (Registrations Under Section 24(c) of FIFRA)
TEP          Typical End-Use Product
TGAI         Technical Grade Active Ingredient
TRR          Total Radioactive Residue
UF           Uncertainty Factor
/zg/g          Micrograms Per Gram
jUg/L •         Micrograms Per Liter
USDA        United States Department of Agriculture
USGS        United States Geological Survey
UV          Ultraviolet
WPS         Worker Protection Standard
                                             VI

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EXECUTIVE SUMMARY

       The Environmental Protection Agency (EPA) has completed its review of public
comments on the revised human health and environmental risk assessments for disulfoton and is
issuing its interim risk management decision. The decisions outlined in this document do not
include the final tolerance reassessment decision for disulfoton.  Revocations, lowering
tolerances, changing definitions and other actions will occur when the Interim Reregistration
Eligibility Decision (IRED) is finalized. Raising or establishing new tolerances will be deferred
until cumulative risks have been considered.  Thirty-three tolerances will be proposed for
revocation now, because either there are no currently registered uses or because the technical
registrant has requested, and the Agency has approved, cancellation of the use on these
commodities. Two .tolerances will be lowered (coffee and peanuts), and several commodity
definitions will be corrected. In addition, six tolerances for barley, wheat, and potatoes will be
revoked consistent with the Agency's determination that uses on these commodities are
inconsistent with FIFRA and must be phased out. The tolerances for barley grain and wheat
grain will be lowered in the interim period before the phase out.  The disulfoton IRED also
provides that 19 tolerances must be established for meat, meat by-products, and meat fat for
cattle, hogs, sheep, horses, and goats, for milk, and for cotton gin by-products, leaf lettuce, and
aspirated grain fractions. As previously mentioned, the final tolerance reassessment, including
establishing the nineteen new tolerances, will be deferred until after cumulative risks for all of
the organophosphates pesticides are considered.

       Disulfoton is an organophosphate insecticide used on a variety of crops. It was first
registered in 1961 and is primarily used to control aphids in vegetable and field crops. Based on
available pesticide usage information from 1987 through 1998, approximately  1.2 million
pounds of disulfoton active ingredient (Ibs ai) are used annually.  However, according to Agency
and registrant estimates, usage has been declining in recent years.

       Overall Risk Summary

       The Agency's human health risk assessment for disulfoton indicates some risk concerns.
Both acute and chronic risks from food are well below the Agency's level of concern. Drinking
water risk estimates based on screening level models, from both ground and surface water
exposures have been assessed and suggest concern for potential surface water exposure. Dietary
exposure from ground water sources of drinking water are not of concern. There are also risk
concerns for occupational handlers who mix, load, and apply disulfoton; for homeowner users;
and for occupational workers who are exposed to disulfoton residues after it is applied to
agricultural crops.  The ecological risk assessment has identified chronic  risk to birds and
mammals that are of concern, as well as risk to aquatic and endangered species.

       Dietary Risk

       Acute and chronic dietary (food) risks are less than 100% of the aPAD and cPAD for the
general U.S. population and all population subgroups. Children (1-6 years), the most highly
                                           Vll

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exposed population group, are exposed to disulfoton at a level of 9.6% of the aPAD at the 99.9th
exposure percentile and 3.5% of the cPAD. No mitigation measures are necessary to reduce
dietary risks from food.

       Drinking Water Risk

       Surface water drinking water estimated concentrations (DWECs) were modeled using
PRZM-EXAMS.  Based on currently registered uses, the surface water DWECs for total
disulfoton (parent + degradates) range from 8.0 ppb to 39.0 ppb for acute exposure, and from 2.0
to 16.7 ppb for chronic exposure.  Therefore, some of the modeled DWEC values exceed the
acute (23 ppb), short-term (14 ppb), and chronic (1.3 ppb) drinking water levels of comparison
(DWLOC) and are of concern to the Agency.

       Ground water DWECs for disulfoton were derived from a Tier I screening-level model
(SCI-GROW), which estimates the maximum ground water concentrations from the application
of a pesticide to crops. The estimated ground water DWEC is 1.2 ppb and does not exceed the
Agency's level of concern for either acute, short-term or chronic exposures.

       Residential Risk

       Disulfoton is currently registered for residential use on small flower gardens, ornamental
flowers and shrubs, including rose bushes and small trees, and outdoor potted plants. MOEs for
residential uses of disulfoton range from 1.1 to 1900. For those scenarios with present risk
concerns, the registrant has agreed to measures that will effectively mitigate risks; therefore,
residential uses that are eligible for reregistration do not exceed the Agency's level of concern.

       Post-Application Residential Risk

       The Agency conducted a worse case residential, post-application risk assessment for
disulfoton. Toddler hand-to-mouth exposure (oral exposure) assessed on the day  of application
results in an MOE of 230  which is not of concern. Therefore, the Agency does not have a
concern for any post-application risks associated with the residential use of disulfoton and  no
risk mitigation is necessary.

       Aggregate Risk

       An aggregate assessment was conducted for exposures through food, residential uses, and
drinking water.  Based on the results of this aggregate assessment, the Agency made an interim
determination that the human health risks from these combined exposures to disulfoton are
within acceptable limits. Although combined disulfoton exposures from food, residential use,
and surface water sources of drinking water appear to "fill" the aggregate risk cup, the drinking
water exposure is based on screening-level modeling estimates. The Agency believes actual
drinking water exposures  are lower than predicted by the model, and has made an interim
determination that disulfoton does "fit" within the dietary risk cup.  As will be described later in
                                          vin

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this IRED document, confirmatory water monitoring and environmental fate data will be
required to verify this conclusion.

       The acute and chronic aggregate risk assessment included only food and drinking water
in contrast to the short-term aggregate assessment which included food, drinking water and
residential exposures: The acute drinking water level of comparison (DWLOC) for children 1-6
years old, the most highly exposed population subgroup, is 23 ppb. The highest or acute surface
water drinking water estimate concentration (DWEC) for total disulfoton (parent + degradates) is
39.0 ppb based on barley use and is greater than the DWLOC (23 ppb). The acute aggregate
assessment therefore exceeds the Agency's level of concern. The short-term DWLOC is 14 ppb.
The highest short-term surface water DWEC of 16.7 ppb is associated with the use on potatoes
and is the only use which nominally exceeds the Agency's short-term level of concern. Lastly,
the chronic DWLOC is 1.3 ppb and is of concern for all uses. Although surface water DWECs
exceed the DWLOCs as indicated above, mitigation measures and additional fate and surface
water data are expected to confirm that aggregate risks do not exceed the Agency's level of
concern.  Conversely, the acute ground water DWEC is 1.2 ppb for total disulfoton and does not
exceed the Agency's level of concern for any aggregate scenario. Residential exposures do not
contribute significantly to the aggregate assessment.

       Occupational Risk

       Occupational exposure to disulfoton is of concern to the Agency and mitigation measures
are necessary.  As part of the Agency's measures to mitigate occupational risks associated with
the use of disulfoton,1 certain use sites are to be deleted or phased out. Among the uses to be
discontinued are barley, potatoes, wheat, and ornamental trees, shrubs, flowers, and groundcover
(field or nursery stock).  In addition to personal protective equipment (PPE) and engineering
controls for handlers, the Agency has considered reductions in the rate and frequency of
applications. Despite these mitigation measures, residual risks are still of concern (MOE<100)
for some occupational handler activities. The Agency has considered the benefits of these uses
and identified measures necessary to mitigate these occupational risks of concern, which are.
summarized at the end of this executive summary.

       Handler Risk

       Occupational risks are of concern (i.e., MOEs < 100) for most mixer/loader and/or
applicator (MLA) scenarios even when maximum PPE (i.e, double layer clothing, gloves, and a
respirator) is used.  MLA risks are also of concern for many scenarios with engineering controls,
even at a level that provides protection from inhalation exposure (closed mixing/loading,
enclosed cabs with air filtration or use of a dust/mist respirator).  For MLAs wearing the
maximum PPE described above and using the Agency's standard assumptions for acres treated
per day, MOEs range from 1.1 to 61 for mixer/loaders, from 1.2  (commercially grown
ornamental shrubs, trees, flowers, groundcover, or potted plants) to 69 for applicators, and from
<1 (commercially grown ornamentals) to 9100 for mixers/loaders/applicators. For MLAs using
the engineering controls described above and standard assumptions for acres treated per day,
                                           IX

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MOEs range from 3.1 to 800 for mixer/loaders and from 1.8 to 160 for applicators.

       Post-Application Risk

       Post-application (re-entry) risks are of concern for workers performing tasks in areas that
have received foliar applications of disulfoton. Restricted-entry intervals (REIs) are needed.
The Agency acknowledges that additional dislodgeable foliar residue data could refine the post-
application risk assessment and potentially reduce the REI for certain crops.  Any data developed
to refine this assessment would need to include residue data on both parent disulfoton and its
toxicologically significant degradates. To mitigate post-application worker risks following foliar
application of the liquid formulation, the following REIs are needed: (1) 26 days for asparagus;
(2)  37 days for overhead sprinkler irrigation and groundboom applications, and 20 days for aerial
applications to potatoes; (3) 16 days for wheat; (4) and 13 days for barley. For non-foliar
application of the liquid formulation and for all granular formulations, the Worker Protection
Standard designates the REI to be 48 hours, or 72 hours in regions where the annual rainfall is
less than 25 inches which are adequate to mitigate post-application worker risks.  If the
ornamental use was eligible for reregistration, post-application risk is of concern and exposure
data for activities such as transplanting or weeding would be required.

       Ecological Risk

       The Agency has ecological risk concerns regarding the acute risks of disulfoton to birds
and mammals, and to freshwater and estuarine invertebrates; and chronic risk concerns to birds
and mammals, freshwater invertebrates, marine and estuarine fish, and invertebrates.  The
ecological risk assessment for disulfoton also identified potential risk concerns for endangered
species and nontarget plants. Risk assessments for both the liquid and granular formulations
resulted in RQ values which exceed the various levels of concern (LOCs).

       Birds and Mammals

       The Agency has some acute and chronic risk concerns for birds and mammals potentially
exposed to the liquid formulation. Acute RQs for birds range from 0.01 to 2.2, with the highest
RQ associated with use on potatoes.  Acute RQs for mammals range from <0.1 to 360, again
with the highest RQ associated with potatoes.  Chronic risk estimates for the liquid formulation
range from 0.02 to 3.4 for birds and from 0.9 to 158 for mammals. Again, the highest RQ is
associated with use on potatoes in the Pacific Northwest. For the remaining agricultural crops,
the highest acute RQ is 0.7 for birds and 121 for mammals. The Agency also has a risk concern
for endangered avian and mammalian species.

       Risk concerns exist for the granular formulation, with potential concerns at the lowest
application rate of 1 Ib ai/A. Acute avian RQs range from 5 to 75,200 and mammalian RQs
range from 0.3 to 257,300.  The highest RQs for both birds and mammals are associated with the
Christmas tree use at the current Section 3 registration at a label rate of 78 Ibs ai/A. Although
the registrant has agreed to substantially reduce the maximum application rate to 4.5 Ibs ai/A for
                                            x

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the Christmas tree use, peak RQs remain of concern for birds (4,350) and mammals (14,900).

       Aquatic Organisms

       Acute risks are of concern for some aquatic organisms, potentially including endangered
species. Acute RQs range from <0.01 to 0.21 for freshwater fish. Estuarine fish RQs range from
<0.01 to 0.02 and are not of concern. For invertebrates, acute RQs range from <0.01 to 2.1 for
freshwater invertebrates, and from <0.01 to 0.55 for estuarine invertebrates. Some of the acute
values for invertebrates are  of concern.

       Chronic risks are of concern for freshwater invertebrates, but not for freshwater fish. The
Agency has a greater chronic risk concern for freshwater invertebrates than for estuarine
invertebrates. Chronic RQs range from <0.01 to 149 for freshwater invertebrates,  and from
<0.01 to 2.3 for estuarine invertebrates. For freshwater fish, chronic RQs range from <0.01 to
0.8, and'for estuarine fish, chronic RQs range from <0.01 to 3.0..

       The highest RQs of concern to both fish and invertebrates are associated with multiple
aerial applications to potatoes, barley, and asparagus.

       Endangered Species

       Potential impacts on endangered aquatic species from several uses of disulfoton were
addressed by  the US Fish and Wildlife Service, which issued two formal Biological Opinions on
disulfoton in  1983 and 1989. Because the disulfoton use pattern has changed significantly since
EPA's last formal consultation with the US Fish and Wildlife Service, EPA conducted a
screening assessment to determine if disulfoton use would result in potential exposure to
endangered species. This analysis identified potential impacts for two bird species which
appeared to occupy habitats in disulfoton areas where disulfoton is used:  the Puerto Rico plain
pigeon and the Mountain plover.

       Further analysis and consultation with local fish and wildlife authorities showed that
there is not a  concern for these two species. Although the Mountain plover occupies habitat
where disulfoton is used, it feeds  only in fields with short vegetation. Disulfoton is used on
barley late in  the growing season, on tall plants that are near maturity. Further, disulfoton use on
barley is being phased out.  The Agency also requested and received technical assistance from
the Fish and Wildlife Service in Puerto Rico, which revealed that the Puerto Rican plain pigeon
does not utilize or otherwise occur in areas of Puerto Rico where coffee is produced. Therefore,
because no adverse impacts to these species are expected, no mitigation is necessary.

       Regulatory Decision

       The Agency is issuing this IRED for disulfoton, as announced in a Notice of Availability
published in the Federal Register. This IRED document includes guidance and requested time
frames for making any necessary  label changes for products containing disulfoton. The Agency
                                           xi

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has decided, to provide a final 30-day opportunity for stakeholders to respond to the disulfoton
interim risk management decision.  On March 26, 2002, the Agency was informed of other
information that may be used to refine post-application risks and will address this issue during
this comment period.  If substantive data or similar comments are received and indicate that any
of the Agency's assumptions need to be refined and that alternate risk mitigation is warranted,
appropriate modifications will be made at that time. Note that neither the tolerance reassessment
nor the reregistration eligibility decision for disulfoton can be considered final until the
cumulative risks for all organophosphate pesticides are considered. The cumulative assessment
may result in further risk mitigation measures for disulfoton.

       Summary of Mitigation Measures

       EPA believes that disulfoton is eligible for reregistration if the registrant takes the
following actions, combined with the general mitigation measures previously described:

       Dietary Risk

•      No label changes are necessary, however certain confirmatory data listed in Section V are
       required.

       Residential Risk

       Only end-use products containing 2% active ingredient or less are eligible for
reregistration.  The following measures are necessary to mitigate residential risk:

•      Limit maximum label rates for disulfoton to 0.3 Ib ai/1000 ft2 for use on flowerbeds; 0.01
       Ib ai/4 ft bush for use on shrubs; and 0.0013 Ib ai/bush for use on rose bushes.

•      Limit the maximum label rate for disulfoton packaged for application with a push type
       spreader to 0.3' Ib ai/1000 ft2.  Products to  be applied by this method do not need to be in
       child resistant packaging, and commercial use of this product is prohibited.

•      Prohibit application of disulfoton with a belly grinder.

•      Prohibit application to flower gardens and ornamental shrubs  with a spoon, measuring
       scoop, shaker can, or by hand, unless the packaging and method of application of the
       end-use product conforms with the performance of a measuring cup and lid packaging
       currently manufactured for the Bayer Advanced Garden 2-in-l Systemic Rose and
       Flower Care® Disulfoton 1% granular product.

•      Package all products marketed and labeled for hand application in child resistant
       packaging with a self-contained measuring device, which serves as the container lid and
       clearly measures the quantity to be applied.  Products marketed and labeled for
       application with a push type spreader do not need to be in child resistant packaging, but
                                           XII

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must be labeled "not for application by hand." Commercial use of the homeowner
product is prohibited.

Delete the following uses from all product labels:  all indoor uses, use in greenhouses,
and use on home vegetable gardens, including use on spinach and tomatoes.

Occupational Risk

The following measures are necessary to mitigate handler risk:

Closed mixing/loading systems for liquid formulations by December 31, 2002;

Closed loading systems for granular formulations by June 2004;

Enclosed cabs plus a dust-mist respirator for all applicators using ground equipment;

Enclosed cockpits for all aerial applicators;

Mechanical flaggers for aerial application; or the use of global positioning system (GPS)
equipment that negates the need for flaggers;

When engineering controls are not feasible, handlers must wear maximum PPE (i.e.,
double layer plothing, chemical-resistant gloves and footwear, and a dust-mist respirator);
and

Application by open, handheld equipment, including belly grinders and bucket and spoon
will be prohibited after June 2004. Where this is currently the application method of
choice, growers will be allowed until June 2004 to transition to another method; and

Phase out of use on barley, wheat, potatoes, and commercially grown ornamental trees,
shrubs, flowers, and groundcovers (field or nursery stock) by June 2005.

The following measures are necessary to mitigate risk to post-application workers:

For soil directed application of the liquid formulation and for all granular formulations,
the Worker Protection Standard designates the REI to be 48 hours, or 72 hours in regions
where the annual rainfall is less than 25 inches.

For foliar application of the liquid formulation, a 26 day REI is necessary for asparagus.
Longer REIs are also necessary for foliar application to barley (16 days), wheat (13
days), and potatoes (20 or 37 days .depending upon the application method). The uses on
barley, wheat, potatoes, and commercially grown ornamental field or nursery stock are to
be phased out by June 2005.
                                   Xlll

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       Ecological Risks

       The following measures are necessary to mitigate ecological risks. Disulfoton is eligible
for reregistration provided that:

•      A precautionary bee statement is added to all product labels for liquid formulations of
       disulfoton

       Use is prohibited within a level, well maintained 25 foot vegetative buffer between
       treated fields and all permanent water bodies. (Refer to the March 2000 USDA Natural
       Resources Conservation Service document: Conservation Buffers to Reduce Pesticide
       Losses for guidance.)

•      No more than one application of disulfoton per calendar year for all crops, except for
       asparagus, barley, coffee, peanuts (North Carlina only), and potatoes, for which no more
       than two applications of disulfoton per calendar year are permitted.

       The maximum application rate for Christmas trees is reduced from 78 to 4.5 Ibs ai/A
       nationally, the use is limited to fir species only, and disulfoton is soil incorporated,
       watered in, or applied to areas with permanent groundcover.

       Use on barley, wheat, potatoes, and commercially grown ornamentals (field or nursery
       stock) is phased out by June 2005.

       Eligible Uses

•      The following uses are eligible for reregistration, pending consideration of the
       cumulative assessment for the OPs: asparagus; beans (lima and snap); cabbage; cole
       crops (broccoli, Brussels sprouts, and cauliflower); lettuce; peppers; peanuts; cotton;
       clover  and radish grown for seed; coffee trees; and Christmas trees.

       Phase Outs

•      The following uses will be phased out by June 2004: barley and wheat, commercially
       grown  ornamentals, and potatoes.
                                           xiv

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 I.
Introduction
       The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) was amended in 1988
 to accelerate the reregistration of products with active ingredients registered prior to November
 1, 1984. The amended Act calls for the development and submission of data to support the
 reregistration of an active ingredient, as well as a review of all submitted data by the U.S.
 Environmental Protection Agency (referred to as EPA or "the Agency").  Reregistration involves
 a thorough review of the scientific database underlying a pesticide's registration. The purpose of
 the Agency's review is to reassess the potential hazards arising from the currently registered uses
 of the pesticide; to determine the need for additional data on health and environmental  effects;
 and to determine whether the pesticide meets the "no unreasonable adverse effects" criteria of
 FIFRA.

       On August 3, 1996, the Food Quality Protection Act of 1996 (FQPA) was signed into
 law.  This Act amends FIFRA to require tolerance reassessment during reregistration.  The
 Agency has decided that, for those chemicals that have tolerances and are undergoing
 reregistration, the tolerance reassessment will be initiated through this reregistration process.
 The Act also requires that by 2006, EPA must review all tolerances in effect on the day before
 the date of the enactment of the FQPA. FQPA also amends the Federal Food, Drug, and
 Cosmetic Act (FFDGA) to require a safety finding in tolerance reassessment based on factors
 including an assessment of cumulative  effects of chemicals with a common mechanism of
 toxicity. Disulfoton belongs to a group of pesticides called organophosphates (OPs), which
 share a common mechanism of toxicity by affecting the nervous system via cholinesterase
 inhibition.  Although FQPA significantly affects the Agency's reregistration process, it does not
 amend any of the existing reregistration deadlines.  Therefore, the Agency is continuing its
 reregistration program while it resolves the remaining issues associated with the implementation
 ofFQPA.

       This document presents the Agency's revised human health and ecological risk
 assessments; its progress toward tolerance reassessment; and the interim reregistration  eligibility
 decision (IRED) for disulfoton. This action is intended to be only the first phase in the
 reregistration process for disulfoton. The Agency will eventually proceed with its assessment of
 the cumulative risk of the OP pesticides and issue a final reregistration eligibility decision (RED)
 for disulfoton. A preliminary cumulative risk assessment for the OPs was released in December,
 2001.              ;

       The implementation ofFQPA has required the Agency to revisit some of its existing
policies relating to the determination and regulation of dietary risk, and has also  raised  a number
 of new issues for which policies need to be created. These issues were refined and developed
through collaboration between the Agency and Advisory Committee, which was composed of
representatives from industry, environmental groups, and other interested parties.

      In addition, the Agency published in the Federal Register on September 29, 2000, a
Pesticide Registration Notice that presents EPA's approach for managing risks from OP
                                           1

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pesticides to occupational users (PR Notice 2000-9).  This Notice, Worker Risk Mitigation for
Organophosphate Pesticides, describes the Agency's baseline approach to managing risks to
handlers and workers of OP pesticides. Generally, basic protective measures such as closed
mixing and loading systems, enclosed cab equipment, or protective clothing, as well as increased
restricted entry intervals will be necessary for most uses where current risk assessments indicate
a risk of concern and such protective measures are feasible.  The policy also states that the
Agency will assess each pesticide individually, and based upon the risk assessment, determine
the need for specific measures tailored to the potential risks of the chemical.  The measures
included in this IRED are consistent with the Worker Pesticide Registration Notice.

       This document consists of six sections. Section I contains the regulatory framework for
reregistration/tolerance reassessment; Section II provides a profile of the use and usage of the
chemical; Section III gives an overview of the revised human health and environmental effects
risk assessments resulting from public comments and other information; Section IV presents the
Agency's decision on interim reregistration eligibility and risk management; and Section V
summarizes the label changes necessary to implement the risk mitigation measures outlined in
Section IV. Finally, the Appendices include Data Call-in (DCI) and other information. The
revised risk assessments and related addenda are not included in this  document, but are available
on the Agency's web page www.epa.gov/pesticides/op,  and in the public docket.

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II.
Chemical Overview
       A.     Regulatory History

       Disulfoton was first registered in 1961 for use as an insecticide. A Registration Standard,
which describes the terms and conditions for continued registration of disulfoton, was issued for
disulfoton in 1984.  Disulfoton is currently registered for use on over 35 crops. There are 49
tolerances for disulfoton in the Code of Federal Regulations. At present, disulfoton is also
registered for domestic outdoor uses on potted plants and ornamentals, including herbaceous
plants, flowers, woody shrubs,  and trees.

       During the public participation process for the reregistration of disulfoton, Bayer
Corporation, the technical registrant, proposed several changes to their disulfoton registrations.
These changes were reflected in the revised disulfoton risk assessment, which was available for
public comment, and later accepted by EPA as interim risk mitigation measures. These changes
included use deletions, voluntary cancellations, rate reductions, and reduction in the number of
applications of disulfoton allowed per year. In addition, various disulfoton end-use registrants
voluntarily canceled products and/or deleted uses that were no longer supported by Bayer.
       B.
       Chemical Identification
       Disulfoton:
                    Common Name:

                    Chemical Name:


                    Chemical Family:

                    Case Number:

                    OPP Chemical Code:

                    Empirical Formula:

                   . Molecular Weight:

                    CAS Registry No!:
                                        Disulfoton

                                         O,O-diethyl S-[2-ethylthio)ethyl]
                                        phosphorodithioate

                                        Organophosphate

                                        0102

                                        032501
                                        274.4 g/mole

                                        298-04-4

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              •     Trade and other names:      Di-Syston, Bayer Advanced Garden

              •     Basic Manufacturer:         Bayer Corporation

       C.     Use Profile

       The following information is limited to the currently registered uses of disulfoton.  Uses
that have been deleted as part of the reregistration process are not included in this IRED
document, except in discussions of risk mitigation in Section IV. Bayer, the sole technical
registrant, has voluntarily canceled the following uses and deleted them from all disulfoton  ;
labels: berries, Bermuda grass, com, all greenhouses, all home vegetable gardens, non-bearing
fruit trees, oats, pecans, tomatoes, and triticale. These use deletions were effective on or before
October 22,2001.  Bayer has voluntarily cancelled disulfoton use on dry beans, peas and lentils,
poplars grown for pulp, sorghum, soybeans, and tobacco. A Federal Register Notice announcing
this request was published on January 10, 2002, and these use deletions became effective on
February 11,2002.

       On March 19, 2002, Bayer requested voluntary cancellation of the end-use product used
to treat cotton seed (EPA Reg No 3125-173). Also, on March 28, 2002, the registrant requested
voluntary cancellation of their end-use products of fertilizer spikes impregnated with disulfoton
(EPA Reg Nos 46260-2,46260-12,  46260-35, and 46260-36). A Federal Register Notice
announcing the cancellation of the cotton seed treatment and impregnated fertilizer spike
registrations is to be published.

Type of Pesticide: Insecticide

Summary of Use Sites:

       Food and Feed Crops -  asparagus, broccoli, Brussels sprouts, cabbage, Chinese cabbage,
       cauliflower, coffee, lettuce, pepper (bell, chili, and pimento), barley, succulent beans
       (lima and snap), cotton, peanuts, white/Irish potato, and wheat.

       Non-Food Crops - clover grown for seed, radish grown for seed, commercially grown
       ornamental flowers/groundcover/herbaceous plants, ornamental shrubs and trees,
       ornamental woody shrubs and vines (field or nursery stock), and Christmas trees.

       Residential - roses, flowers, and ornamental shrubs.

       Public Health - none.

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Formulation Types Registered:

       Technical Grade/Manufacturer-Use Product (MPX liquid 68% active ingredient (ai); and
       solid 97.6% ai.

       End-Use Product (EP\ emulsifiable concentrate (EC) 23 - 85% ai; granular 1 - 15% ai;
       pellet/tableted 1 - 2% ai; and impregnated material 1% ai.,

Target Pests: Invertebrates (insects and related organisms) consisting of aphids (asparagus, bird
cherry-oat aphid, greenbug, green peach, lettuce root, root), beetle (Colorado potato, cottonwood
leaf, elm leaf, flea, Mexican bean), billbugs (lawn), bugs (lace), borers, fly (Hessian),
grasshoppers, leafhoppers, leafminer (birch, holly), mealybugs, midge (sorghum), mite (banks
grass, red spider), moth (Nantucket pine tip, pine shoot, pine tip), psyllids (potato), scale
(camellia, European elm, rhododendron, soft brown, soft, tea), thrips, webworm (mimosa),
wireworm (southern potato), and whiteflies.

Methods and Rates of Application:

       Equipment - aircraft; drip irrigation; high or low volume ground sprayer; tractor-drawn
       spreader; belly grinder; push-type spreader; measuring container; shaker can; soil injector
       equipment; sprayer; and sprinkler irrigation.

       Methods - broadcast; chemigation, high volume spray (dilute); low volume spray
       (concentrate); seed treatment; soil band or broadcast treatment; soil in-furrow treatment
       (by drill, injection, and hill drop); soil incorporation treatment by irrigation; side dressing
       treatment; and top dressing treatment.

Label Use Rates: Maximum label use rates vary by crop. For most of the food and feed crops,
the maximum label use rate is 1-2.5 Ibs ai/acre/season.  However, disulfoton is used at a rate of 3
,lbs ai/acre (A) for potatoes, and 8.3 Ibs ai/A for coffee. The highest rates are used on ornamental
flowers, trees, and shrubs.

Use Classification: Both Restricted and Nonrestricted

       D.    Estimated Usage of Disulfoton

       This  section summarizes the best estimates available for many of the pesticide uses of
disulfoton, based on available pesticide usage information for 1987 through 1998, which is why
some deleted uses are listed. A full listing of all uses of disulfoton, with the corresponding use
and usage data for each site is in the "Quantitative Usage Analysis" document, which is available
in the public docket and on the internet. The data, reported on an aggregate and site (crop) basis,
reflect annual fluctuations in use patterns, as well as the variability in using data from various
information  sources.  Approximately 1.2 million pounds of disulfoton ai are used annually,
according to Agency, and registrant estimates; however, in recent years use has been declining.
                                           .5

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       Disulfoton is primarily used to control aphids in vegetable and field crops.  Important
regional uses of disulfoton include asparagus grown in California and Washington; Christmas
trees (Fraser firs) grown primarily in the mountains of North Carolina; broccoli, Brussels
sprouts, cabbage, cauliflower, and lettuce grown in the Salinas Valley of California; chili    :
peppers grown in California; lima beans in Georgia; and radish grown for seed in Washington's
Columbia River Basin.
Table 1. Disulfoton Estimated Usage for Representative Sites
Crop
Asparagus
Barley
Beans, dry*
Beans, lima and snap
Broccoli
Brussel sprouts
Cabbage
Cauliflower
Chili peppers
Cotton
Com, field*
Com, sweet*
Lima beans
Lettuce
Peanuts
Peas, green*
Potatoes
Sorghum*
Soybeans*
Tobacco*
Winter Wheat
Lbs. Active Ingredient
Applied (Wt. Avg.)1
37,000
29,000
2,000
14,000
22,000
1,000
7,000
10,000
4,000
420,000
36,000
2,000
4,000
13,000
47,000
1,000
120,000
20,000
26,000
62,000
180,000
Percent Crop Treated
(Wt. Avg.)2
40%
1%
<1%
12%
10%
20%
6%
17%
25%
5%
<1%
<1%
7%
3%
3%
<1%
4%
<1%
<1%
4%
1%
Percent Crop
Treated (Likely
Maximum)3
55% National
80% CA, WA
1%
4%
34%
21%
40%
9%
25%
40%
8%
<1%
1%
14%
8%
5%
7%
7%
1%
<1%
7%
1%

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Crop
Residential/Commercial
Ornamentals
Horticultural Nurseries
Woodlands, including Christmas
trees (national)
Christmas Trees (NC only)
Lbs. Active Ingredient
Applied (Wt. Avg.)1
11,000
9,000
80,000
60,000
Percent Crop Treated
(Wt. Avg.)2
N/A
N/A
2%
65%
Percent Crop
Treated (Likely
Maximum)3
N/A
N/A
2%
70%
1 Weighted Average is based on data for 1987-1998; with data from recent years weighted more heavily.
2 Weighted average percent crop treated used in chronic dietary assessment.
3 Maximum percent crop treated used in acute dietary assessment.
* Use on this crop has been voluntarily canceled; usage information reflects past use.
 No data were available for the following crops: coffee, clover, popcorn, lentils, or triticale.

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III.    Summary of Disulfoton Risk Assessment

       The purpose of this summary is to assist the reader by identifying the key features and
findings of the human health and ecological risk assessments, and to better understand the
conclusions reached in the assessments. Following is a list of EPA's revised human health and
ecological risk assessments and supporting information that were used to formulate the findings
and conclusions for the OP pesticide disulfoton. The listed documents may be found on the
Agency's web page at www.epa.gov/pesticides/op and in the OPP public docket. The OPP
docket is located in Room 119, Crystal mall #2, 1921 Jefferson Davis Highway, Arlington, VA.
It is open Monday through Friday, excluding legal holidays from 8:30 am to 4:00 pm.

Human Health Risks

       Risk Assessment and Reregistration Eligibility Decision (RED) Documents for Disulfoton
       (Revised Risk Assessment, Phase 4), February 10, 2000.
       Disulfoton:  Revised (3rd) Report of the Hazard Identification Assessment Review
       Committee,  April 10, 2001.
•      Review and Determination of Dermal (Hand and Forearm) and Inhalation Exposure to
       Disulfoton Resulting from Residential Application of Bayer Advanced Garden 2-in-l
       Systemic Rose and Flower Care to Shrubs and Flower Beds, June 6, 2001.
•      Revised Residential Exposure Assessment and Recommendations for the Reregistration
       Eligibility Decision (RED) Documents for Disulfoton, May 31, 2001 and addendum,
       August 9, 2002.
•      Revised Occupational Exposure Assessment for the Reregistration Eligibility Decision
       Document for Disulfoton, June 15, 2001.
       Health Effects Division Toxicity Chapter for Reregistration Eligibility Decision (RED),
       June 25, 2001.
•      Disulfoton:  Aggregate Risk Assessment, March 6, 2002.

Environmental Fate and Ecological Effects

       Reregistration Eligibility Document for Disulfoton, September 5, 2000 and its addendum
       March 25, 2002.
       [Review of] The Interagency Study of the Impact of Pesticide Use on Ground-Water in
       North Carolina, August 1, 2000.
•      Additional Information and Clarification for the Disulfoton RED [Review of California
       Surface Water Monitoring], October 20, 2000.
       Disulfoton Residues in Groundwater Found in the Virginia BMP Study, November 20,
       2001.
•      Endangered Species Addendum to EFED 's Disulfoton Science Chapter,  January 24, 2002
•      Puerto Rican Plain Pigeon and Disulfoton,  April 24, 2002
       Disulfoton:  Summary of Estimated Drinking Water Concentrations (ED WCs)for Use in
       the Human Health Risk Assessment, February 25, 2002.

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Benefits and Alternatives Analysis

•      Asparagus Benefits Assessment for Disulfoton, September 11, 2001.
•      Benefits of Disulfoton on Selected Vegetable Crops and Cotton, September 27, 2001.
•      Benefits Assessment for Disulfoton Use on Potatoes and Radish Seed, September 28,
       2001.
•      Use of Disulfoton on Bell and Pimento Peppers, November 3, 2001.
•      Cursory Assessment of Disulfoton Use in Coffee in Puerto Rico, November 26, 2001.
•      Response to Questions Concerning Disulfoton Posed by Special Review and
       Reregistration Division [Regarding Ornamentals], December 17, 2001.
•      Analysis of Disulfoton Use on Fraser Fir Christmas Trees in Western North Carolina,
       July 9, 2002.
       A.
Human Health Risk Assessment
       EPA issued its preliminary risk assessments for disulfoton in January, 1999 for public
comment. Based on the comments received and additional information, the Agency revised the
risk assessments and presented this information at a Technical Briefing on February 3, 2000.
This was followed by another opportunity for public comment on risk management for this
pesticide. In response to comments and studies submitted during the public comment periods,
the following major revisions were made to the risk assessments:

       Refinement of the acute dietary risk assessment to use probabilistic (Monte Carlo)
       techniques;

•      Incorporation of data from FDA's Surveillance Monitoring Program and USDA's
       Pesticide Data Program (PDP) into the dietary risk assessment;

•      Incorporation of data from the Occupational and Residential Re-Entry Task Force into
       the occupational and residential risk assessments;

•      Incorporation of residential exposure monitoring and toxicology data on the 1% granular
       home use product;

•      Incorporation of data from an acute delayed neurotoxicity study in hens;

•      Incorporation of recent label changes into the water, occupational, residential, and
       environmental assessments;

•      Incorporation' of new information and methodologies into the water assessment, such as
       the index reservoir and percent crop area factor;

•      An assessment of the impacts  of disulfoton  on endangered species; and

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       An assessment of benefits and alternatives on the remaining currently registered
       agricultural uses that are subject to reregistration.

              1.     Dietary Risk from Food

                    a.     Toxicity

       The Agency has reviewed all toxicity studies submitted, and has determined that the
toxicity database is substantially complete, and that it supports an IRED for all currently
registered uses. Only the developmental neurotoxicity study is outstanding, which is scheduled .
to be submitted to the Agency by November 2004.  Further details on the toxicity of disulfoton
can be found in the April 10,2001 Hazard Identification Assessment Review Committee
(HIARC) Report for Disulfoton. A brief overview of the studies used for the dietary risk
assessment is outlined in Table 2 in this document.

       The Agency has also considered the toxicity of the metabolites of disulfoton found in
plants and animals, as well as the degradates found in the environment. Of the metabolites and
degradates identified, the following are of toxicological concern: disulfoton sulfoxide,
disulfoton sulfone, disulfoton oxygen analogue (demeton-S), disulfoton oxygen analogue
sulfoxide, and disulfoton oxygen analogue sulfone. Therefore, the Agency included these
compounds in the dietary and drinking water risk assessments  for disulfoton, and in the
reassessment of disulfoton tolerances.  Because toxicology data are not available for the
metabolites and degradates for the purposes of assessing risks, the Agency assumes that the
degradates are as toxic as the parent. Therefore, toxicological  endpoints for the parent were used
to assess the risk of the parent and degradates.

                    b.     FQPA Safety Factor

       The FQPA Safety Factor (SF) was removed (reduced to IX) for disulfoton because:

       The  database of toxicity studies necessary to assess the applicability of the FQPA safety
       factor is complete, including an acceptable two-generation reproduction study in rats,
       acceptable prenatal developmental toxicity studies in rats and rabbits, an acute delayed
       neurotoxicity study in hens, and neurotoxicity studies in rats.

•      These studies show no evidence of either neurotoxicity or increased susceptibility of
       fetuses or offspring in prenatal or postnatal studies in rabbits or rats.

•      Adequate actual data, surrogate data, and/or modeling outputs are available to
       satisfactorily assess dietary and residential exposure and to provide a screening level :
       drinking water exposure assessment.

•      The assumptions and models used in the assessments do not underestimate the potential
       risk for infants  and children.
                                            10

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In summary, the Agency has determined that the IX FQPA SF is applicable for all populations
potentially exposed to disulfoton.

                    c.     Population Adjusted Dose (PAD)

       The PAD is a term that characterizes the dietary risk of a chemical, and reflects the
Reference Dose (RfD), either acute or chronic, that has been adjusted to account for the FQPA
SF (i.e., RfD + FQPA SF).  In the case of disulfoton, the FQPA SF is IX; therefore, both the
acute and chronic PADs are identical to the corresponding acute and chronic RiDs. The Agency
applied the conventional uncertainty factor (UF) of 100X to account for both interspecies
extrapolation (10X) and intraspecies variability (10X). These UFs were applied to the No
Observed Adverse Effect Level (NOAEL) selected for risk assessment. The acute PAD (aPAD)
is 0.0025 mg/kg/day, and the chronic PAD (cPAD) is 0.00013 mg/kg/day. Table 2 below
summarizes the toxicological endpoints used hi the disulfoton dietary risk assessment.

 Table 2. Summary of Toxicological Endpoints  for the Dietary Risk Assessment
Exposure Duration
and Route
Acute Dietary
(one day)
Chronic Dietary
Toxicology Endpoint and Dose
NOAEL = 0.25 mg/kg/day;
LOAEL = 0.75 mg/kg/day,
based on muscle fasciculation,
plasma and red blood cell
cholinesterase inhibition
NOAEL = 0.01 3 mg/kg/day;
LOAEL = 0.094 mg/kg/day,
based on plasma, red blood cell,
and corneal cholinesterase
inhibition; and brain
cholinesterase inhibition in
females only
Toxicology Study
Used
acute neurotoxicity
study in rats,
MRID 42755801
1-yeartoxicity
study in dogs,
MRID 44248002
UF/FQPASF
100/1
100/1
PAD
(mg/kg/day)
0.0025
0.00013
NOAEL: no observed adverse effect level
LOAEL: lowest observed adverse effect level

                    d.     Exposure Assumptions

       The Agency's dietary (food) risk assessment for disulfoton Uses the Dietary Exposure
Evaluation Model (DEEM™),  which incorporates consumption data generated from the U.S.
Department of Agriculture's Continuing Surveys of Food Intakes by Individuals (CSFII), 1989-
1992. Extensive monitoring data have been generated for disulfoton by the USDA Pesticide
Data Program (PDP) and the U.S. Food and Drag Administration (FDA).  However, only FDA
data were used in the dietary risk assessment, because the PDP data do not include all of the
cholinesterase-inhibiting metabolites of toxicological concern. However, the available PDP data
support the FDA findings. Of the hundreds of samples analyzed by FDA between 1992 and
1998, no residues were detected except for the following:  broccoli with 2 detects in 309
                                          11

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samples; cabbage with 5 detects in 510 samples; lettuce with 4 detects in 866 samples; and
potatoes with 6 detects in 1133 samples. Residue values for non-detects were assumed to be
equal to one-half the limit of quantitation (LOQ). Therefore, for the acute dietary risk
assessment, the entire distribution for each food item of single day food consumption was
combined with anticipated residues estimated from FDA monitoring data or field trial data
generated by the registrant.  For the chronic dietary risk assessment, the three-day average
consumption for the U.S. and sub-populations was combined with average residues in
commodities to determine average exposure. The Agency uses the estimated maximum percent
crop treated for acute risk assessments and the average estimated percent crop treated for chronic
risk assessments.

                    e.     Acute Dietary (Food) Risk

       For disulfoton, a dietary risk estimate that is less than 100% of the aPAD is not of
concern to the Agency. The Agency conducted a probabilistic (Monte Carlo) analysis which
estimated a dietary exposure of 9.6% of the aPAD at the 99.9th exposure percentile for the most
highly exposed subpopulation (children 1 - 6 years). The acute dietary (food) risk for disulfoton
is less than 100% of the aPAD for all subpopulations, and is therefore not of concern to the
Agency. Results of the Agency's acute dietary risk assessment for food are summarized in Table
3.

TableS. Acute Dietary Risk Estimates
Population
US population (total)
All infants (<1 yr)
Children (1-6 yr)
99.9th percentile
Exposure (mg/kg/day)
0.000176
0.000218
0.000239
% aPAD
7.0
. 8.7
9.6
                     f.     Chronic Dietary (Food) Risk

        For disulfoton, a dietary (food) risk estimate that is less than 100% of the cPAD is not of
 concern to the Agency.  The chronic dietary exposure is estimated to be 3.5% of the cPAD for
 the most highly exposed subgroup (children 1-6 years). The chronic dietary (food) risk for :
 disulfoton is less than 100% of the cPAD for all subpopulations, and is therefore not of concern
 to the Agency. Results of the Agency's chronic dietary risk assessment for food are
 summarized in Table 4.
                                           12

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Table 4. Chronic Dietary Risk Estimates
Population
US population (total)
All infants (<1 yr)
Children (1-6 yr)
Average Exposure
(mg/kg/day)
0.000003
0.000001
0.000005
% cPAD
2.3
0.9
3.5
              2.     Dietary Risk from Drinking Water

       Drinking water exposure to pesticides can occur through surface and ground water
contamination. The Agency considers both acute (one day) and chronic (lifetime) drinking water
risks and uses either modeling or actual monitoring data, if available. EPA assessed the potential
of disulfoton to reach surface or ground water sources of drinking water based on available
ground and surface water monitoring data, laboratory and field studies, and Agency models.
Limited surface and ground water monitoring data were available for disulfoton; however,
because most monitoring did not include the degradates of concern and because the monitoring
data were not considered to be nationally representative, the Agency used modeling to predict
the potential concentration of total disulfoton (parent + degradates) in drinking water.

       The available laboratory and field data for disulfoton indicate that both parent disulfoton
and the following degradates may be'found in surface and ground water: disulfoton sulfonic
acid, disulfoton oxygen analogue sulfonic acid, disulfoton sulfone, disulfoton oxygen analogue
sulfone, disulfoton sulfoxide, and disulfoton oxygen analogue sulfoxide. Data for disulfoton and
other OPs suggest that the sulfoxide and sulfone degradates are more mobile and persistent than
the parent. For parent disulfoton, the estimated upper 90th percentile upper bound on the mean
half-life of the aerobic soil metabolism was 6.12 days (non first order decay). The aerobic soil
metabolism half-life, is greater than 17 days for disulfoton sulfoxide and greater than 150 days
for disulfoton sulfone. The 90th percent upper bound on the mean half life for total  disulfoton
residues is 259 days.

       No aerobic or anaerobic aquatic metabolism data are available for disulfoton or its
degradates, which are necessary to fully understand the environmental fate. Hence, as part of
this IRED, the Agency is requiring aerobic and anaerobic aquatic metabolism data (OPPTS
Guidelines 835.4300 and 835.4400) and mobility, adsorption, and desorption data (OPPTS
Guideline 835.1240) for the disulfoton parent and sulfoxide and sulfone degradates. These
studies are confirmatory data.

       As part of the cumulative assessment for all OPs, the Agency contacted nearly all 50
states to determine whether any ground or surface water monitoring had been conducted for OP
pesticides over the last ten years.  A total often states (i.e., Hawaii, Kansas, Kentucky,
Maryland, Michigan, Nebraska, North Carolina, West Virginia, Wisconsin, and Wyoming)
conducted monitoring for disulfoton parent, but no detections were reported.  Only  one state,
                                            13

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North Carolina, conducted monitoring for disulfoton and its sulfone and sulfoxide degradates.

       The results of the Agency's drinking water analysis are summarized here.  Details of this
analysis, are found in the following supporting technical documents: Reregistration Eligibility
Document for Disulfoton, September 5, 2000, and its addendum, March 25, 2002; Disulfoton:
Aggregate Risk Assessment, March 6, 2002; [Review of] The Interagency Study of the Impact of
Pesticide Use on Ground-Water in North Carolina, August 1, 2000; Additional Information and
Clarification for the Disulfoton RED [Review of California Surface Water Monitoring], October
20,2000; Disulfoton Residues in Groundwater Found in the Virginia BMP Study, November 20,
2001; and. Disulfoton:  Summary of Estimated Drinking Water Concentrations (EDWCs)for Use
in the Human Health Risk Assessment, February 25, 2002. All of these documents are available
in the public docket and on the internet.
                    a.
                           Surface Water
       Monitoring
       There are limited surface water monitoring data for disulfoton. The available data show
few detections, including the US Geological Survey (USGS) National Assessment of Water
Quality (NAWQA) data and a Virginia Tech Best Management Practice monitoring study. The
NAWQA data up to 1998 included 5196 samples, with 29 samples detecting parent disulfoton
ranging from < 0.017 ppb to 0.06 ppb. The USGS NAWQA study is ongoing; however, the
most recent NAWQA data have not yet been released and is therefore not available to EPA. The
Virginia Tech monitoring study was conducted to evaluate the effectiveness of Best
Management Practices in a 3616-acre watershed in Westmoreland County, Virginia.
Approximately half of the watershed is in agriculture and the other half is forested. From the
study, three samples detected parent disulfoton in 2 of the 8 monitoring sites with values ranging
from 0.37 to 6.11 ppb. As stated above, a major limitation of the surface water monitoring data,
including the NAWQA and Virginia Tech data, is that the analysis did not include the sulfoxide
and sulfone degradates. The importance of which is that the Agency is concerned that the
sulfoxide and sulfone degradates may be more mobile and persistent than the parent.

       The California Department of Pesticide Regulation (CDPR) also maintains a database of
surface water monitoring data collected in the state. This database contains the results of studies
conducted by a number of agencies and researchers and therefore, may have been included or
reported elsewhere (e.g., STORET, NAWQA). The CDPR database contains results of surface
water samples collected during 1991 to 1999,  from ten counties, which were analyzed for a
number of pesticides, including disulfoton (parent only). Of the 860 samples collected and  ,
analyzed, two resulted in detections of parent  disulfoton residues, both of which were 0.06 ppb.
Although CDPR also keeps records of all agriculture pesticide use in California, it is not clear
which usage contributed to these detections.

       A pilot reservoir monitoring program was initiated jointly by EPA's Office of Pesticide
Programs and Office of Ground Water and Drinking Water, and by USGS NAWQA to assess
                                           14

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pesticide concentrations in raw and finished drinking water. Disulfoton and its sulfone and
sulfoxide degradates were included in this study. Parent disulfoton was not detected, but the
sulfone degradate was detected (0.013 ppb) in 1 of 316 samples, and the sulfoxide degradate was
also detected (0.006 ppb) in 1 of 316 samples. This pilot study shows that the degradates can be
found in surface water sources of drinking water. No detections of disulfoton or its degradates
were found in finished drinking water samples.  Please refer to the following internet address for
additional information on the pilot reservoir monitoring program:
http://www.epa.gov/pesticides/cumulative/pra-op/iii  e 3-f.pdf.

       The interpretation of the monitoring data is limited by the lack of correlation between
sampling dates and the use patterns of the pesticide within the study's drainage basin.
Additionally, the sample locations were not associated with actual drinking water intakes for
surface water. Limitations for the monitoring studies include the use of different limits of
detection between studies, lack of information concerning disulfoton use around sampling sites,
and lack of data concerning the hydrogeology of the study sites.

       Modeling

       Surface water drinking water estimated concentrations (DWECs) were derived from the
Tier IIPRZM-EXAMS model with the Index Reservoir and percent cropped area (PCA), which
is a screening-level model designed to provide high-end estimates of potential pesticide
exposure. The following surface water modeling scenarios were chosen for disulfoton to
represent high run-off sites:

•      barley in the Southern Piedmont of Virginia
•      cotton in the Southern Mississippi Valley Silty Uplands of Mississippi
•      potatoes in New England and Eastern New York Upland of Maine
•      spring wheat in the Rolling Till Prairie of South Dakota.

       The maximum registered application rates for the respective crops were used for the
modeled scenarios. These scenarios represent major uses and generally reflect the highest use
rates and highest number of pounds that are annually applied, and were chosen because they
were expected to represent the upper 10th percentile of potential runoff from sites where the
representative crop is grown.  Disulfoton use on Christmas trees was not specifically modeled
due to lack of an appropriate scenario.  However, surface and groundwater monitoring conducted
by the North Carolina Department of Agriculture showed no detections of disulfoton or its
sulfoxide or sulfone degradates.                                                 >

       Also, as part of DWEC calculation, the values were adjusted by the PCA, which is a
factor that represents the maximum percent of the area within the watershed that is planted and
treated in the crop(s) under evaluation. For the crops that are treated with disulfoton, the PCAs
used to estimate the DWECs are 20% for cotton and 56% for wheat. For all other crops, the
default PCA of 87% ;was used. Better estimates of the PCA for these crops would reduce the
uncertainty associated with the DWECs.
                                           15

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       Based on current labels, the DWECs for disulfoton (parent only) in surface water range
from 2.8 to 15.5 ppb for acute exposure, and from 0.2 to 1.6 ppb for chronic exposure.  The  ,
DWECs for total disulfoton (parent + degradates) range from 8.0 to 39.0 ppb for acute exposure,
and from 2.0 to 16.7 ppb for chronic exposure.  Table 5 summarizes the modeled DWEC for the
crop scenarios previously mentioned.

Table 5.  Surface Water Concentrations of Disulfoton Residues (Parent + Degradates)
Crop Scenario
(PCA)
Barley (0.87)
Barley (0.87)
Cotton (0.20)
Potatoes (0.87)
Western States
Potatoes (0.87)
East of Rockies
Spring Wheat
(0.56)
Application Rate and
Method
1.0 Ib ai/A
foliar
1.0 Ib ai/A
granular, soil applied
1.0 Ib ai/A
ground and soil
3.0 Ib ai/A
ground and soil
1.0 Ib ai/A
foliar
0.75 Ib ai/A
foliar
Number of
Applications per
Season
2
2
1 •
1
3
1
Concentration (ppb)
Peak
(Acute Risk)
15.51 parent
34.53 total
14.88 parent
39.05 total
7.21 parent
12.59 total
6.89 parent
12.53 total
13. 09 parent
34.37 total
2.79 parent
8.02 total
Annual Average
(Short-Term or
Chronic Risk)
1.61 parent
. 7.62 total
1.22 parent
10.01 total
0.40 parent
1.96 total
0.46 parent
4.77 total
1.09 parent
16.72 total
0.24 parent
2.39 total
                    b.
Ground Water
       Monitoring
       Limited ground water monitoring data from a study in Virginia and another in Wisconsin
are available for disulfoton.  The same Best Management Practices study in Westmoreland
County, Virginia that was conducted to evaluate surface water was also conducted for ground
water.  The ground water component was started in 1986 and ended in June 1997. Monthly
samples were taken from eight ground water monitoring wells and were analyzed for a number
of pesticides, including disulfoton (parent only). The study resulted in a total of six detections of
disulfoton parent at levels ranging from 0.04 to 2.87 ppb in 5 of the 8 wells.  The mean of all the
disulfoton detections is 0.39 ppb.

       The Wisconsin study showed detections of disulfoton parent in 14 of 29 samples in 25
wells.  The concentration of disulfoton detected ranged from 4 to 100 ppb. The high
concentrations of disulfoton detected in the Wisconsin groundwater monitoring study were
unexpected, given the low mobility and persistence of disulfoton in the environment.  EPA
                                          16

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concludes that these detections may have occurred at a highly vulnerable site, which is not
typical of the entire disulfoton use area. The Wisconsin study also had quality assurance and
quality control issues, and no detections of disulfoton were reported in follow up sampling.
However, this lack of detections does not discount previous detections because groundwater is a
dynamic system. Because groundwater is constantly moving and undergoing biotic and/or
abiotic interactions, pesticides and other contaminants are not always detected. Although the
Wisconsin values can not be ignored, they are not appropriate for use in a national ground water
assessment.

       Neither the Virginia nor the Wisconsin studies included analysis for the sulfoxide and
sulfone degradates. Mississippi and Texas also monitored for both disulfoton and degradates in
ground water, but found no  detections. Also, no detections of disulfoton parent were found hi
3,000 ground water samples in the NAWQA database.

       Another ground water monitoring study was conducted by the North Carolina
Department of Agriculture under the direction of the North Carolina Pesticide Board to
determine if labeled uses of pesticide products, including disulfoton, were impacting the ground
water resources of North Carolina. In phase I of the study, 55 wells representing the major
drinking water aquifers qf the state were sampled; and hi phase II, 97 monitoring wells were
installed adjacent to and down-gradient from areas where pesticides were applied. These
monitoring well sites were selected based on the vulnerability of ground water to risk of
contamination from use of pesticides. Monitoring of disulfoton residues were conducted hi the
five counties where disulfoton use was reported. There were no detections of disulfoton
residues, including the sulfone  and sulfoxide degradates,  hi any of the samples collected in the
study.

       Modeling

       Groundwater DWECs for disulfoton and its degradates were estimated using the Tier I
SCI-GROW screening-level model.  The Agency used a scenario where disulfoton was applied
to potatoes once per season at a rate of 3 Ib ai/A to generate a high-end to bounding estimate of
disulfoton concentration hi ground water.  The resultant DWEC of disulfoton parent in
groundwater was 0.02 ppb,  and the DWEC of total disulfoton residues (parent + degradates) was
1.2 ppb.

       The SCI-GROW model used various environmental fate parameters as inputs, including
the half-life of total disulfoton residues and an average K^ value of 551 mL/g for parent
disulfoton. The Koc value is an estimate of the mobility of a chemical in soil. Because the
degradates are persistent, and because the Agency does not have adequate data to fully
understand the environmental fate of the degradates,  EPA assumed a 259 day half-life derived
from the 90th percentile upper confidence limit of the mean aerobic soil half-life as an input in
the SCI-GROW model.  In comparison, the 90th percentile upper confidence limit of the mean
aerobic soil half-life for parent alone is 6.12 days. Provided the confirmatory fate data
demonstrate that the mobility of the degradates is less than the parent, the DWECs predicted by
                                           17

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the SCI-GROW model would not be underestimates.

             3.     Residential and Occupational Risk

       Residents or homeowners can be exposed to a pesticide through mixing, loading, or
applying a pesticide, or through entering or performing other activities on treated areas.  Risk for
all of these potentially exposed populations is measured by a Margin of Exposure (MOE), which
determines how close the occupational or residential exposure comes to a NOAEL.

       Occupational workers, such as individual farmers or custom applicators, can be exposed
to a pesticide through mixing, loading, and/or applying a pesticide, or re-entering treated sites.
Risk for all of these potentially exposed populations is also measured by  an MOE.  For
disulfoton, MOEs greater than 100 are not of concern to the Agency for both residential  and
occupational exposure.

       The occupational and residential risk assessments are summarized herein; for more
details, see the folio whig documents: Risk Assessment and Reregistration Eligibility Decision
(RED) Documents for Disulfoton (Revised Risk Assessment, Phase 4), February 10, 2000;
Disulfoton: Revised (3rd) Report of the Hazard Identification Assessment Review Committee,
April 10, 2001; Revised Residential Exposure Assessment and Recommendations for the
Reregistration Eligibility Decision (RED) Documents for Disulfoton, May 31, 2001 and
addendum, August 9, 2002; Review and Determination of Dermal (Hand and Forearm) and
Inhalation Exposure to Disulfoton Resulting from Residential Application of Bayer Advanced
Garden 2-in-l Systemic Rose and Flower Care to Shrubs and Flower Beds, June 6,2001;
Revised Occupational Exposure Assessment for the Reregistration Eligibility Decision
Document for Disulfoton, June 15, 2001; Health Effects Division Toxicity Chapter for
Reregistration Eligibility Decision (RED), June  25, 2001; and Disulfoton: Aggregate Risk
Assessment, March 6, 2002. All of these documents are available in the public docket and on the
internet.

                    a.     Toxicity

       All risk calculations are based on the most current toxicity information available  for
disulfoton. The toxicological endpoints and other factors used in the residential and
occupational risk assessments for disulfoton are listed in Table 6.
                                           18

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Table 6. Toxicological Endpoints for Residential and Occupational Risk Assessment
Route and Duration
of Exposure
Dermal Short-Term (one
day to one month)
Incidental Ingestion by
Children, Short Term (one
day to one month)
Dermal Intermediate-Term
(one month to several
months)
Inhalation (any time
duration)
Toxicological Endpoint and
Dose
NOAEL = 0.5 mg/kg/day,
LOAEL = 1 .0 mg/kg/day, based
on plasma and brain cholinesterase
inhibition after 3 days of dosing
NOAEL = 0.03 mg/kg/day,
LOAEL = 0.06 mg/kg/day, based
on plasma, red blood cell, and
brain cholinesterase inhibition in
female rats
NOAEL = 0.03 mg/kg/day;
LOAEL = 0.06 mg/kg/day, based
on plasma, red blood cell, and
brain cholinesterase inhibition in
female rats
NOAEL = 0.045 mg/kg/day
LOAEL = 0.39 mg/kg/day, based
on plasma, red blood cell, and
brain cholinesterase inhibition
Study
3 -day rat dermal study on 1%
granular product
(MRID 45239602)
Special 6-month dietary
cholinesterase study in rats
(MRID 43058401)
Special 6-month dietary study
in rats to measure
cholinesterase inhibition
(MRID 43058401), supported
by 2-generation reproductive
toxicity study
90-day inhalation toxicity
study in the rat
(MRID 41224301)
Percent
Absorption
N/A
N/A
36f
N/A
fA dermal absorption factor of 36% (relative to oral absorption) is used in route-to-route extrapolation, and was
derived from a dermal absorption study in rats.

       When the revised human health risk assessment was conducted for disulfoton, EPA used
a period of 1 to 7 days to assess short-term exposure, and a period from 7 days to several months
to assess intermediate term exposure. Consequently, both short- and intermediate-term exposure
and risk were assessed for disulfoton. On June 6, 2001, the Agency revised its approach and
now uses a short-term exposure duration of 1 day to 1 month, and an intermediate-term exposure
duration of 1 to 6 months.  Because disulfoton applications are generally made only pre-plant or
at-plant, and specify only one application per year, it is reasonable to believe that handlers will
not treat crops with  disulfoton for a duration of more than one month; hence intermediate (1-6
months) and also chronic (> 6 months) occupational exposures to disulfoton are not expected to
occur. Even though a few sites allow more than one application per crop or per year (i.e.,
asparagus, barley, potatoes, wheat), current labels specify discrete time intervals between
applications, thus it  is expected that commercial applicators would not be exposed for more than
14 days and therefore would not receive intermediate or long-term (chronic) exposures.

       In the February 2000 human health risk assessment, EPA used a NOAEL of 0.5
mg/kg/day from a 21-day dermal toxicity study in rabbits to assess risk to occupational and
residential handlers  from short-term exposure.  Subsequently, the technical registrant submitted
data  from a 3-day dermal toxicity study in the rat, and that study's NOAEL of 0.4 mg/kg/day
was chosen to assess risk from short-term exposure. The rat is considered to be a more sensitive
species than the rabbit to the toxicological effects of disulfoton. Although the 3-day dermal
                                           19

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toxicity study in the rat is acceptable to assess residential exposure, because residential exposure
is expected to be less than 3 days, it may underestimate short-term (one day to one month)
exposure to commercial handlers, who could be exposed for up to 14 days.  Therefore, a 21-day
dermal study in the rat is required as part of the IRED as confirmatory data to better characterize
risk to commercial handlers. Until the 21-day study is received, the dermal short-term
occupational assessment for commercial handlers will be based on the 3-day study, which may
underestimate potential risk, but is more appropriate to use than the available six-month oral rat
study, which will most likely overestimate exposure to commercial handlers.

       The results of the acute toxicity studies with disulfotori are listed in Table 7. Disulfoton
is classified as Toxicity Category I for all acute endpoints.
Guideline
Number
81-1
81-2
81-3
81-4
81-5
81-6
Study
acute oral
acute dermal
acute inhalation
eye irritation
dermal irritation
dermal
sensitization
MRID Number
139595
139595
147754
Waived
Waived
Waived
Results
LD50= Male: 6.2 mg/kg
LD50= Female: 1.9 mg/kg
LD50 = Male: 15.9 mg/kg
LD50= Female: 3.6 mg/kg
LC50 = Male: 0.06 mg/L
LC50 = Female: 0.89 mg/L
Data requirement waived because
disulfoton was too toxic to test; EPA
assumed results
Toxicity
Category
I
I
I :
severe eye
irritant
severe skin
irritant
severe
sensitizer
                     b.
Residential Risk Assessment
       Residential Uses of Disulfoton

       Current residential uses of disulfoton include small flower gardens, ornamental flowers
and shrubs, including rose bushes and small trees, and outdoor potted plants.  Bayer, the
technical registrant, is only supporting a 1% granular homeowner product for reregistration:
Bayer Advanced 2-in-l Systemic Rose and Flower Care (EPA Reg. No. 3125-152), which is
packaged in small (2 or 5 Ib) containers and labeled for spot treatment only.  Bayer voluntarily
canceled Di-Syston Systemic Insecticide for Vegetables (EPA Reg. No. 3125-126), effective
October 23, 2000, and has deleted all indoor uses, including greenhouse use.  However, at the
present time, other registrants are producing and selling various granular formulations (1-2% ai)
registered for a variety of indoor and outdoor residential uses. Therefore, the Agency has
evaluated potential exposure and risk from residential uses of disulfoton.
                                           20

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       At present, disulfoton can be applied by hand to potted plants, ornamentals, flowers, and
rose bushes. When disulfoton is applied by hand, granular product is typically distributed at the
base of the plant or shrub to be treated using a measuring cup, shaker can, or spoon, followed by
soil incorporation or watering. Disulfoton can also be applied by belly grinder or push-type
spreader when treatment is made prior to planting. Application rates for products containing
disulfoton labeled for residential garden use were converted to units of pounds ai per area treated
to simplify the residential exposure assessment.

       Residential Applicator Assessment

       For homeowner exposure assessments, the Agency does not consider personal protective
equipment (PPE). Homeowners often lack access to PPE and do not possess expertise in the
proper use of PPE.  Also, PPE requirements for homeowners are difficult to enforce. As a result,
homeowner assessments are completed using a single scenario based on the use of short-sleeved
shirts, short pants, arid shoes and socks, which are common homeowner attire during the
pesticide application season.  In addition,'only short-term exposures were assessed, as the
Agency does not believe homeowners who apply disulfoton will be exposed for more than 30
days.  The exposure scenarios included the following:

•      Loading/Applying Granulars with a Belly Grinder,

•   .   Loading/Applying Granulars with a Push Type Spreader,

       Loading/Applying Granulars with a Spoon, Shaker Can, Measuring Scoop, or by Hand,

•      Loading/Applying Bayer Advanced Garden 2-in-l Systemic Rose and Flower Care by
       Hand Using a Measuring Cup/Lid, and

       Applying Insecticidal Spikes.

       The residential exposure assessment was conducted using chemical-specific exposure
monitoring  data for the 1% granular product (MRID 45333401) and generic exposure monitoring
data from three sources: push-type spreader study conducted by the Outdoor Residential
Exposure Task Force (ORETF); proprietary exposure monitoring data for another granular
pesticide; and generic exposure monitoring data from Pesticide Handlers  Exposure Data
(PHED). EPA assumed that home gardeners could treat as many as 25 shrubs, 50 rose bushes, or
20 potted plants in a given day.  The Agency also assumed that the area of a garden treated with
disulfoton would be 1OOO ft2. As indicated in Table 6, the residential risk assessment was based
on a dermal short-term NOAEL of 0.5 mg/kg/day and an inhalation NOAEL of 0.045
mg/kg/day.

       Residential risk for each scenario is expressed as a MOE, and is summarized in Table 8.
For disulfoton, residential risks with MOEs less than 100 are of concern.' Combined (dermal +
inhalation) residential MOEs for currently registered residential uses of disulfoton range from
                                          21

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1.1 to 1900.

TableS. Homeowner Short-Term Risks from Disulfoton
Exposure
Scenario
Loading/
applying
granulars using
a belly grinder
Loading/
applying
granulars using
a push-type
spreader
Loading/
applying
granulars using
a spoon,
measuring
scoop, shaker
can, or by hand
Loading/
applying Bayer
Advanced.
Garden 2-in-l
Systemic Rose
and Flower
Care!&
Disulfoton 1%
granulars using
a measuring
cup/lid
Applying
insecticidal
spikes
Crop Type
Flower Gardens
(pre-planting)
Flower Gardens
Ornamental
Shrubs/ Small
Trees
Roses
Flower Gardens
Ornamental
Shrubs/ Small
Trees
Outdoor Potted
Plants
Roses
Flowerbeds
Shrubs
Roses
Roses/Trees
Amount
Handled/
Day
1,000ft2
1,000 ft2
25 shrubs
50 bushes
1,000 ft2
25 shrubs
20 pots
50 bushes
1000ft2
25 shrubs
50 bushes
No Data
Maximum
Application
Rate
O.Slbai/lOOOft2
0.3 Ib ai/1,000 ft2
0.011bai/4ft
shrub
0.00 126 Ibai/bush
0.3 Ib ai/1,000 ft2
0.011bai/4ft
shrub
0.00034 lbai/6"
pot
0.00 126 Ibai/bush
O^llbai/lOOOfl2
0.011bai/4ft
shrub
0.0013 Ibai/bush
No Data
Dermal
MOE
1.1
172
210
820
34
41
1500
160
5600
1500
' 5900
No Data
Inhalation
MOE
170
1.2E4
1.4E4
5.5E4
2.3E5
2.8E5
1.0E7
1.1E6
1.2E3
9.7E2
3.7E3
No Data
Combined
MOE
1.1
170
200
810
34
41
1500
160
960
490
1900
No Data
       Residential Post-Application Assessment

       Disulfoton can be used on flower gardens, roses, bushes, trees, and other ornamentals
where exposure to adults and children may occur after the granular is applied.  Potential post-
application exposure can occur during transplanting garden flowers, ornamental shrubs, and
trees. Potential exposure can also occur from non-harvest activities, such as weeding and from
incidental soil ingestion by toddlers from hand-to-mouth exposure.
                                          22

-------
       The Agency assessed post-application exposure to toddlers, because this is expected to be
a worst-case scenario for which EPA has data. EPA used surrogate data to assess exposure and
assumed that 20% of the amount of disulfoton applied is found in the uppermost 1 centimeter of
soil on the day of application. Soil ingestion was assumed to be 100 mg/day for a 15 kg child.
EPA assumed that 1% granular disulfoton was applied at the maximum rate of 13 Ibs ai/A (to
flowerbeds) and soil incorporated.  Using these conservative assumptions, the Agency estimated
a MOE of 230  for a toddler from hand-to-mouth exposure on the day of treatment. Because the
MOE is greater than 100, EPA does not have a risk concern for toddler hand-to-mouth or any
other residential post-application exposure to disulfoton.

                    c.     Aggregate Risk

       Aggregate risk considers the combined exposures from food, drinking water, residential
and other non-occupational uses of a pesticide.  For disulfoton, the aggregate risk considers food,
drinking water, and residential exposures. There are no other disulfoton non-occupational
exposures, such as use on golf courses, which would contribute to aggregate risk.  Based on
these sources of exposure, acute, chronic, and short-term aggregate exposure and risk
assessments were conducted for disulfoton.  Results of the aggregate risk assessment are
summarized here, and are discussed extensively in the document Disulfoton: Aggregate Risk
Assessment, March 6, 2002, which is available in the public docket and on the internet.

       To determine the maximum contribution of disulfoton from water in the diet, the Agency
first looks at how much of the overall risk is contributed by food and residential use, and then
determines a drinking water level of comparison (DWLOC) to determine whether modeled or
monitored water concentrations exceed this value.  The Agency uses the DWLOC as a surrogate
measure of risk associated with exposure from pesticides in drinking water.  The DWLOC is the
maximum concentration in drinking water which, when considered together with other sources
of ambient  exposure, such as residential use, does not exceed a level of concern. The DWLOC
is then compared with the DWEC to determine whether there is a potential concern for aggregate
exposure and risk. When the DWEC is less  than the DWLOC, the Agency can make a
determination of safety for aggregate exposure. When the DWEC is greater than the DWLOC,
the Agency may not be able to make a determination of safety.  EPA may also require additional
data concerning potential water contamination.  However,  in certain situations where the DWEC
is not significantly greater than the DWLOC, EPA may be able to conclude that existing uses do
not present a risk concern, depending on the nature and conservatism of the assessment used.  On
December 3, 2001, EPA released its preliminary assessment of cumulative risks of OP
pesticides, which included a probabilistic drinking water assessment for OP pesticides that may
allow EPA  to refine the nature of the risk. The preliminary results of that assessment suggest
that risk from drinking water exposure to disulfoton and other OP pesticides may in fact be lower
than the modeled estimates.

       Acute and chronic aggregate risk for disulfoton included only food and drinking water
sources of exposure. Short-term aggregate risk included food, drinking water, and residential
exposure. A comparison of DWLOCs with the DWECs is given in Table 9.  Only the DWLOCs
                                          23

-------
associated with children 1-6 years old are presented in Table 9, because this is the most highly
exposed population subgroup, which results in the lowest and most protective DWLOC for
acute, chronic, and short-term sources of exposure. As indicated in Table 9, the peak (acute)
surface water DWECs are less than the acute DWLOC for all crop scenarios and are not of
concern, except for disulfoton use on barley and potatoes (east of the Rockies).  The average
surface water DWECs are greater than the chronic DWLOC for all scenarios and are of potential
concern. Also, the average surface water DWECs are less than the short-term DWLOC for all
scenarios and are not of concern, except for disulfoton use on potatoes (east of the Rockies). For
purposes of comparison, EPA included a conservative, high-end scenario for cotton with a PCA
of 87% to represent the remaining minor crops. The peak surface water DWEC for this alternate
cotton scenario is comparable to the highest peak surface water DWEC of the scenarios listed in
Table 9; therefore, the peak DWEC of 39.0 ppb should be used to evaluate drinking water risks
for all registered crops. Also, the ground water DWEC is less than the DWLOCs for all
exposures, and is therefore not of concern.

Table 9. Aggregate Comparison of DWLOCs with DWECs
Crops
Barley
Cotton
Potatoes
Wheat
Application Type
foliar (liquid)
soil (granular)
soil (granular)
soil (granular)
foliar (liquid)
East of Rockies
foliar (liquid)
DWECs (ppb)*
Surface Water
Peak
34.5
39.0
12.6
12.5
34.4
8.0
Avg**
7.6
10.0
2.0
4.8
16.7
2.4
Ground
Water
1.2
DWLOCs (ppb)
(Children 1-6 yrs)
Acute
23
Chronic
1.3
Short-
Term
14
* DWECs include disulfoton parent and degradates
** Average DWECs are compared to both chronic and short-term DWLOCs

                    d.     Occupational Risk Assessment

       Workers can be exposed to a pesticide through mixing, loading, and/or applying a
pesticide, or re-entering treated sites.  Occupational handlers of disulfoton include:  individual
farmers or growers who mix, load, and/or apply pesticides, and professional or custom
agricultural applicators. Risk to potentially exposed workers is measured by a Margin of
Exposure (MOE). For disulfoton, occupational MOEs greater than 100 are not of risk concern to
the Agency.
                                           24

-------
       Occupational Exposure

       EPA assessed occupational exposure to disulfoton using the PHED Version 1.1; ORETF
data; and proprietary data, including chemical-specific data submitted by the technical registrant
for disulfoton. In addition, standard default assumptions about average body weight, work day,
and area treated daily were used to calculate risk estimates. Application rates used in this
assessment are derived directly from current disulfoton labels.  Worker exposure and risk
estimates are based on the best data currently available to the Agency. The quality of the data
used for each scenario assessed is discussed in the occupational and residential exposure
assessment for disulfoton, which is available on the internet and in the public docket.

       Anticipated use patterns and application methods, range of application rates, and daily
amount treated were derived from current labeling. The current labels specify application rates
of 3.75 to 7.5 grams product per foot of height for a tree or shrub; 2.5 oz product per inch of
trunk diameter measured 4 feet from the ground for trees; and 5 Ib product per 1000 ft of row for
field grown plants. For purposes of risk assessment, the Agency has converted the rates on
ornamentals to 37 Ib'ai/A for trees, 109 Ib ai/A for shrubs, and 29 Ib ai/A for field grown
ornamental flowers and groundcoveri  The Agency typically uses values for acres treated per day
that are thought to represent 8 hours of application work for specific types of application
equipment.

       Occupational handler exposure assessments are conducted by the Agency using different
levels of personal protection.  The Agency typically evaluates all exposures with minimal
protection and then adds additional protective measures in a tiered approach to determine the
level of personal protective equipment necessary to obtain appropriate MOEs. The lowest level
(baseline) of personal protective equipment (PPE) includes long sleeve shirts, long pants, shoes,
and socks.  A single layer of PPE includes the addition of chemical-resistant gloves to the
standard attire of long sleeves, long pants, shoes, and socks. A respirator may also be added if
there is a concern for inhalation exposure. If MOEs at that level of PPE are less than 100,
increasing levels of PPE are applied (i.e., coveralls are added to provide a double layer of
protective clothing).' If MOEs are still less than 100 with a double layer of PPE, then
engineering controls are applied. The typical disulfoton label specifies maximum PPE for
agricultural products.  The types of protection, including PPE and engineering controls that were
used to calculate occupational exposure from disulfoton include the following:
       Baseline:
       Minimum PPE:

       Maximum PPE:
       Engineering Controls:
Long-sleeved shirt and long pants, shoes and socks.
Baseline clothing, plus chemical-resistant gloves, with or
without a dust/mist respirator.
Coveralls over long-sleeved shirt and long pants, plus
chemical-resistant gloves, with and without a dust/mist
respirator.
Closed mixing/loading systems for liquids (mechanical
closed mixing/loading or transfer systems); Closed loading
systems for granulars (Smartbox® or LockNLoad®);
                                           25

-------
                                  Enclosed Cockpits or Enclosed Cabs with or without
                                  inhalation protection (air filtration).

       Disulfoton is not expected to be used on an intermediate (greater than one month) or
long-term basis; therefore, the occupational exposure assessment is based on the redefined short-
term duration (one day to one month).  The Agency considers the tasks performed by a pesticide
worker, pesticide formulation, application method, application rate, and area treated per day in
assessing occupational exposure. EPA considers both direct and indirect (or secondary)
exposure and risk that may result from the use of the pesticide,  such as handlers not directly
involved in mixing/loading or applying the chemical.

       Handler Risk

       Inhalation and dermal exposure to disulfoton can result  from occupational use. The
Agency assessed dermal and inhalation risks (MOEs) for each crop currently registered for
disulfoton. For disulfoton, occupational MOEs greater than 100 are not of risk concern to the
Agency.

       As summarized in Table 10, occupational risks are of^concern (i.e., MOEs < 100) for all
scenarios, even with the use of maximum PPE (i.e, double layer clothing,  gloves, and a
respirator). Handler risks are of concern for many scenarios with engineering controls, even at a
level that provides protection from inhalation exposure (closed mixing/loading, enclosed cabs,
with air filtration or dust/mist respirator).  Engineering controls with inhalation protection are
considered to be the maximum feasible risk mitigation. For handlers wearing the maximum PPE
and using the standard assumptions for acres treated per day, MOEs range from 1.1 to 61 for
mixer/loaders, from 1.2 to 69 for applicators, and from <1 to 9100 for
mixers/loaders/applicators. For handlers using engineering controls and using the standard
assumptions for acres treated per day, MOEs range from 3.1 to 800 for mixer/loaders and from
1.8 to 160 for applicators.  The route of exposure that significantly contributes to the risk (risk
driver) depends upon the formulation used, the worker activity, and the level of protective
equipment or engineering controls.

       The Agency is also aware that disulfoton is applied to Christmas trees (Fraser fir) in
North Carolina with a motorcycle or all-terrain vehicle equipped with a spreader. However, no
data are available to assess this scenario.  To assess occupational risks associated with this type
of equipment, EPA has included this scenario under the assessment for a tractor drawn spreader.
Because EPA believes that use of the tractor drawn spreader data results in an overestimate of
actual exposure, the Agency  is requiring confirmatory exposure data for the motorcycle or all-
terrain vehicle spreader as part of this IRED.
                                           26

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       Post-Application Risks
       The Agency also assessed post-application risks to workers who may be exposed to
disulfoton when they enter previously treated fields, because their skin may contact treated
surfaces. Exposures are directly related to the kind of tasks performed. EPA estimates the
amount of pesticide exposure to post-application workers over tune based on various studies.
The Agency evaluates this information to determine the number of days following application
that must elapse before the pesticide residues dissipate to a level where worker MOEs equal or
exceed 100 while wearing baseline attire. Baseline attire is defined as long-sleeved shirt, long
pants, shoes and socks. Based on the results of the post-application worker assessment, the
Agency establishes restricted entry intervals (REIs) before workers may enter treated areas.  At
present, the Worker Protection Standard designates the disulfoton REI to be 48 hours, or 72   .
hours in regions where the annual rainfall is less than 25 inches.

       The Agency completed a post-application exposure assessment for disulfoton for the
following scenarios: irrigating, scouting, thinning, and weeding immature or low-foliage crops
(i.e., asparagus, barley, cotton, potatoes and wheat). The short-term dermal NOAEL of 0.5
mg/kg/day based on a 3-day dermal toxicity study in rats (Table 6) was used to assess potential
dermal exposure to workers re-entering treated fields.  The post-application assessment is also
based on 8 hours of worker daily exposure and the default transfer coefficients (Tcs) shown in
Table 11. Although three chemical-specific dislodgeable foliar residue (DFR) studies were
conducted for disulfoton, EPA has determined that none of these studies are sufficient for use in
the post-application assessment. Therefore, EPA roughly estimated the exposure and risk to
post-application workers and handlers using an assumption that 20% of the initial application
remained as a DFR immediately following application, and the residue degraded into nontoxic
by-products at a rate of 10% per day.

       For post-application risks to disulfoton, an MOE of 100 or greater is not of concern to the
Agency, and REIs for the assessed crops are determined when the MOE reaches 100.  Table 11
summarizes the occupational post-application risks following foliar applications of disulfoton.
In summary, for foliar applications of disulfoton, EPA has  a post-application risk concern for all
crops except cotton.

Table 11. Occupational Post-Application Risks from Foliar Applications of Disulfoton
Crop
Asparagus
Barley
Cotton (SLN)
Application
Rate (Ib ai/A)
1.0
1.0
0.2
Tasks of
Concern
Irrigating,
scouting,
thinning,
weeding
immature or
low foliage
plants
Timing of
Application
fem stage (3 per
year; 120 DTK)
after tillering
(30 DTK)
Before boll
opens (30 DTK)
Transfer
Coefficient
300
100
100
MOE
6.5
101
20
105
108
Days
After
Treatment
1
26
1
16
1
                                           38

-------
Crop
Potatoes (East
of Rockies)
Potatoes
(OR, ID, UT,
WA only)
Wheat
Wheat (SLN)
Application
Rate (Ib ai/A)
0.5
3.0
• 0.75
1.0
Tasks of
Concern

Timing of
Application
When pest
appears (3 per
season; 30 DTH)
As needed (1 per
season; 60 DTH)
Post-plant (after
tillering; 30
DTH)
Two per season
(30 DTH)
Transfer
Coefficient
300
300
100
100
MOE
14
107
2.4
51
100
29
102
20
105 ,
Days
After
Treatment
1
20
1
30
37
1
13
1
16
DTH - Days to harvest
                    e.     Incident Reports
       Human Incident Reports

       The Agency also reviews any incident data that may be available and applicable. There
have been a significant number of occupational poisoning incidents associated with disulfoton,
resulting in adverse health effects. Poison Control Center data from 1985 to 1992 indicate that
disulfoton ranked third highest among OPs for the percent of individuals hospitalized for
occupational poisoning, with 27 individuals hospitalized following exposure to disulfoton alone
and 28 individuals hospitalized following exposure to multiple chemicals, including disulfoton.
Data from the California Department of Pesticide Regulation show that disulfoton ranked 11th
highest in the number of worker poisonings, with 0.22 poisonings per 1000 pesticide
applications from 1982 to 1989.

       Pet Incident Reports

       Recent incidents of accidental pet poisonings (dogs) have been reported through the
National Pesticide Information Center, NPIC (formerly the National Pesticide
Telecommunication Network, NPTN).  These incidences have been associated with the 1 and 2%
granular products used by homeowners. According to the American Society for the Prevention
of Cruelty to Animals, disulfoton is the second most common pesticide associated with
veterinary poisonings.  Because of its high toxicity, only a small amount is required to poison a
cat, dog, or other domestic animal.
       B.
Environmental Risk Assessment
       A summary of the Agency's environmental risk assessment is presented below.  For
                                          39

-------
detailed discussions of all aspects of the environmental risk assessment, see the document,
Reregistration Eligibility Decision for Disulfoton, September 5, 2000 and its addendum March
25, 2002; and Endangered Species Addendum to EFED 's Disulfoton Science Chapter, January
24, 2002, which are available in the public docket and on the internet.

              1.     Environmental Fate and Transport

       In soil, disulfoton is not expected to undergo significant hydrolysis or volatilization.
Disulfoton parent photochemically degrades rapidly by sunlight on soil, and in water where light
can penetrate. Disulfoton is metabolized or oxidized in soil to the corresponding sulfoxide and
sulfone degradates, and the half-life of disulfoton parent in soil is less than 6 days. Field
dissipation studies confirm that disulfoton does not persist in the environment.  Disulfoton is not
considered mobile under convective-dispersive processes, but it has been detected in
groundwater monitoring conducted in highly vulnerable areas. The mobility of disulfoton,
which can be represented as a K^, ranged from 383 to 888 mL/g carbon with a mean Koc of 551.

       Disulfoton's major degradates, disulfoton sulfone and sulfoxide, are more persistent and
.mobile than the parent. Two aerobic soil metabolism studies showed an average half life of 166
days. In a field study, as much as 35% of the applied disulfoton remained in soil as disulfoton
sulfone after 367 days. Thus the sulfone and sulfoxide degradates appear to be much more
persistent than parent in soil.  The other degradates were either not identified or occurred at
much lower concentrations. The Agency is concerned that the sulfoxide and sulfone degradates
have a high potential to reach ground and surface water. In field testing, degradates were
detected at a depth of 18  inches, indicating potential mobility. The Agency has limited data
regarding the persistence of the degradates and lacks the absorption/desorption data necessary to
confirm the mobility of the degradates.  EPA does not have data on the aerobic or anaerobic
aquatic metabolism of disulfoton and its degradates, nor does it have data on the mobility and
leaching potential of the degradates.  Thus, these data are necessary to confirm the findings in
the disulfoton IRED.

              2.     Ecological Risk Assessment

       The Agency's ecological risk assessment compares toxicity endpoints from ecological
toxicity studies to estimated environmental concentrations (EECs) based on environmental fate
characteristics and pesticide use data. To evaluate the potential risk to nontarget organisms from
the use of disulfoton products, the Agency calculates a Risk Quotient (RQ), which is the ratio of
the EEC to the toxicity endpoint values, such as the median lethal dose (LD50) or the median
lethal concentration (LC50). These RQ values are then compared to the Agency's levels of
concern (LOCs), which indicates whether a chemical, when used as directed, has the potential to
cause undesirable effects on nontarget organisms.  In general, the higher the RQ the greater the
concern. When the RQ exceeds the LOG for a particular category, the Agency presumes a risk
of concern to that category. The LOCs and the corresponding risk presumptions are presented in
Table 12.
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Table 12. LOCs and Associated Risk Presumptions
IF...
THEN the Agency presumes...
Mammals and Birds
The acute RQ > LOG of 0.5,
The acute RQ >LOC of 0.2,
The acute RQ > LOG of 0,1 ,
The chronic RQ > LOG of 1
Acute risk
Risk that may be mitigated through restricted use
Acute effects may occur in Endangered species
Chronic risk and
Chronic effects may occur in Endangered species
Fish and Aquatic Invertebrates
The acute RQ > LOG of 0.5
The acute RQ > LOG of 0. 1
The acute RQ >LOC of 0.05
The chronic'RQ > LOG of 1
Acute risk
Risk that may be mitigated through restricted use
Acute effects may occur in Endangered species
Chronic risk and
Chronic effects may occur in Endangered species
Plants
TheRQ>LOCofl .
Acute risk and endangered plants may be affected
                     a.     Ecological Hazard Profile

       The Agency has a robust toxicity database for disulfoton and the two primary degradates,
disulfoton sulfoxide and disulfoton sulfone. Data for birds showed disulfoton to be highly to
very highly toxic for acute oral gavage testing, and highly toxic for subacute dietary testing.
Additionally, the major degradates are moderately to highly toxic to avian species on a dietary
basis.  The effects in avian reproduction testing included decreased adult and hatchling body
weight. The results of small mammal acute oral studies indicated that disulfoton and the sulfone
degradate are very highly toxic. Rat reproductive toxicity studies demonstrated decreased litter
size, lowered pup survival, and decreased pup weight.  Acute contact studies on honey bees
showed disulfoton to be moderately toxic to honey bees, while disulfoton sulfone and sulfoxide
are very highly toxic.                          .

       The laboratory data for freshwater fish indicate that disulfoton is slightly to very highly
toxic in acute tests. The two major degradates,  disulfoton sulfone and sulfoxide are  slightly to
highly toxic to freshwater fish on an acute basis. In a fish early life stage test on fresh water fish,
disulfoton impacted the growth of fry. For freshwater invertebrates, the results indicate that
disulfoton and its degradates are very highly toxic in acute tests, and affects survival, growth,
and the number of young/adult in chronic tests.  Disulfoton is highly toxic to estuarine fish in
acute tests, and in chronic tests, disulfoton impacts the  reproduction, as well as larval growth and
survival.  In testing with estuarine/marine invertebrates, disulfoton is highly to very  highly toxic
in acute tests, and production and survival of young were adversely affected in chronic tests.
                                            41

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                     b.
Risk to Birds and Mammals
       EPA uses models to estimate exposure of animals to disulfoton. For terrestrial birds and
mammals, the Agency estimates peak and average concentrations of pesticide residues over time
on various wildlife food items. Acute risk to birds and mammals, including endangered species,
were predicted for both the granular and liquid formulations. The Agency estimated chronic risk
to birds and mammals from the liquid formulation only, because of the uncertainty in calculating
fate and exposure of the active ingredient as the granules dissipate.

       The Agency's assessment suggests the potential for the liquid formulation to cause acute
and chronic effects to birds and mammals  for uses other than soil injection and in-furrow
applications. An analysis of the use patterns other than soil injection and in-furrow application
indicate that the least risk is from the Texas 24(c) use on cotton and the greatest is from
chemigation to potatoes in the Pacific Northwest. Based on peak exposure estimates, the acute
RQs for birds range from 0.01 to 2.2 and for mammals from 0.05 to 360.  Chronic RQs are
calculated from both peak and average concentrations over time. Therefore, chronic RQs for
birds range from 0.02 (average for granivores) to 19 (peak for herbivores feeding on short grass).
However, the latter RQ declines to 3.4 when based on the average residue value for herbivores
feeding on short grass. Using the same scenarios, chronic RQs range from 0.9 (average for
granivores) to 900 (peak for herbivores feeding on short grass) with a decrease in the latter value
to 158 for average residues in short grass.  In summary, except for soil injection and in-furrow
applications, all use patterns are of concern to the Agency for acute and chronic effects to birds
and mammals, including endangered species.

       Birds and mammals may be exposed to granular pesticides by ingesting granules when
foraging for food or grit. They also may be further exposed by other routes, such as walking on
exposed granules or drinking water contaminated by granules. The Agency's assessment
suggests potential for the granular formulation to cause acute risk to birds from a single
application at or above the lowest application rate of 1.0 Ib ai/A, even when the material is
incorporated. The acute RQs for small birds range from 0.1 for the in-furrow, 1 Ib ai/A rate on
cotton to approximately 75,200 for 78 Ib ai/A, unincorporated spot treatment to Christmas trees.
For the same use patterns, small mammal acute RQs range from 0.3 to 257,300. However, at a
lower application rate of 4.5 Ib ai/A to Christmas trees, the highest avian and mammalian RQs
are reduced to 4,350 and 14,900, respectively. When the Christmas tree use is excluded, RQs for
birds range from 0.1 to 346, and RQs for mammals range from 0.3 to 1184. The highest ELQs are
associated with use of disulfoton on some  commercially grown ornamentals.

       The North Carolina Christmas Tree community has submitted numerous testimonials
emphasizing the ever increasing numbers and diversity of wildlife, including game animals, such
as turkey rearing young amidst the trees, song birds,  rodents, and foxes. Although this
information is intended to suggest there is  little or no negative population impact from disulfoton
use in combination with other pesticides or cultural practices as well, documented surveys or
research is needed for the Agency to corroborate these  conclusions.  Although it is not clear
whether there are population effects, the risk assessments suggests that there is acute risk to
                                          42

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nontarget birds and mammals exposed to disulfoton.

                    c.     Risk to Insects

       Disulfoton is moderately toxic to honey bees and its sulfoxide and sulfone degradates are
highly toxic to bees. A 24-hour residual study on the liquid formulation indicated no toxicity to
honey bees following exposure to alfalfa that had been treated 3 hours earlier at a rate of 1.0 Ib
ai/A.  However, there is some uncertainty as to the risk from higher application rates associated
with aerial and foliar applications, and from later exposure and longer time periods to the more
toxic degradates.

                    d.     Risk to Aquatic Animals

       To assess potential risk to aquatic animals, the Agency uses a computer model to
generate EECs of disulfoton in surface water.  Unlike the drinking water assessment described in
the human health risk assessment section  of this document, the ecological water resource
assessment does not include the index reservoir and percent crop area factor. .The index
reservoir and percent crop area factor represent a drinking water reservoir, not the variety of
aquatic habitats, such as ponds adjacent to treated fields, relevant to a risk assessment for aquatic
animals. Therefore, the EECs used to assess exposure to aquatic animals are not the same as the
DWEC values used to assess human dietary exposure from drinking water sources.

       Freshwater Fish

       The  acute risk level of concern (LOG) to freshwater fish is not exceeded for any use
patterns, with RQs ranging from O.01 to 0.21. When disulfoton is applied at rates greater than
or equal to 1.0 Ib ai/A; the LOG for restricted use is exceeded. Also, the endangered species
LOG is exceeded from either a single, unincorporated application at rates greater than or equal to
0.75 Ib ai/A or 2 or more unincorporated applications at 0.2 Ibs ai/A. The RQs for chronic risk
to freshwater fish are less than or equal to 0.8, and therefore do not exceed the acute LOG.
These RQs do not preclude possible fish kills from the use of disulfoton.  There are three
incident reports offish kills associated with disulfoton use. However, only one of the three
reported fish kills was attributed solely to disulfoton, whereas use of disulfoton and other
pesticides were associated with the other two reported fish kills.

       Freshwater Invertebrates

       The  freshwater invertebrate acute risk is of concern for some disulfoton uses with RQs
ranging from O.01 to 2.1.  Similarly, chronic risk is of concern for nearly all modeled sites and
application regimes with RQs ranging from <0.01 to 149. For both acute and chronic risks to
invertebrates, the highest RQ is based on multiple applications to barley and asparagus. Risks to
endangered species are of concern for all uses, except those where disulfoton  is applied by soil
injection.
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       The North Carolina Christmas tree industry provided information that has contributed to
a refinement of the Agency's risk assessment for aquatic organisms from Christmas tree farming.
Specifically, this information indicate limited and localized potential exposure from use of the
granular formulation on Christmas trees, and that any estuarine exposure is precluded.
Moreover, because the primary aquatic sites adjacent to tree farms are streams and not ponds,
disulfoton residues in these streams will be lower and of shorter duration than those that would
have been predicted if standard models had been used. In addition, two rapid assessment macro
invertebrate surveys of streams in the Western region of North Carolina  indicate that when
conservation measures associated with Christmas tree farming are implemented, there may be
only slight, short-term impact to aquatic macro invertebrates from disulfoton use.

       Estuarine/Marine Fish

       The acute risk to estuarine and marine fish is low with RQs for all modeled crops are less
than 0.05. However, there is some uncertainty to these risk estimates due to the limitations of
the pond scenario to predict exposure to marine/estuarine organisms, and that the only species
tested (i.e., Sheepshead minnow) probably does not represent the true range of sensitivity of
marine or estuarine fish.

       Modeling and the results of the fish full life-cycle test indicate that only some of the uses
on barley and asparagus, if located adjacent to estuaries, may be of chronic risk concern with
RQs ranging from 2 to 3.  All other modeled uses had RQs less than or equal to 1 and are not of
concern. In addition to the previously stated uncertainties, other uncertainties concerning
chronic risk are the duration adult fish must be exposed to disulfoton for their reproductive
systems to be affected, and when in their reproductive cycle is the impact occurring. For
example, even if adults are affected after an exposure of only a week, disulfoton residues may
dissipate from an area within several days resulting in little or no chronic risk. Therefore, there
is some uncertainty in acute and chronic risk to estuarine and marine fish.

       Estuarine/Marine Invertebrates

       Similar to the risks to estuarine fish, the same uncertainties associated with exposure
apply to estuarine invertebrates. Most of the modeled scenarios do not exceed the acute or
restricted use criteria for marine and estuarine invertebrates. The RQs range from <0.01 to 0.55,
with the highest RQ reflecting multiple applications of the liquid formulation to barley and
asparagus.  Although nearly all uses result in endangered species risk concerns, currently there
are no marine or estuarine invertebrates listed as endangered. The modeled crop scenarios do
not show the potential for chronic risk to marine and estuarine invertebrates, except for some
uses on cotton, barley, and asparagus, which have RQs between  1.2 and  2.3.
                    e.
                           Risk to Plants
       EPA was unable to conduct a risk assessment for nontarget plants due to a lack of test
data. Nontarget plant testing was not required in the Registration Standard because disulfoton is
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not a herbicide. However, because of phytotoxicity statements on the current Di-Syston SEC
label, the Agency is concerned about potential risk to nontarget plants. Given that disulfoton is
applied to growing crops, it is unlikely to result in significant nontarget risks to plants.
Confirmatory data are needed to determine the extent of any risk that may exist. To address this
concern, Tier I plant toxicity data are required (OPPTS Guidelines 850.4100 and 850.4150).

                     f.     Risks to  Endangered Species

       Disulfoton was included in the formal Section 7 consultation with the US Fish and
Wildlife Service (USFWS) under the Endangered Species Act for the  1983 cluster reviews for
corn, cotton, soybean and sorghum. The Biological Opinion, which is the formal USFWS
response, stated that these uses of disulfoton would jeopardize the continued existence of the
valley elderberry longhorn beetle, delta green ground beetle, and the Everglade snail kite.

       Disulfoton was also included in the reinitiated Biological Opinion of 1989 from the
USFWS. In this opinion, the Service found jeopardy to two amphibian species, fifteen species of
freshwater fish, and one bird species from the uses on crops and forests. Terrestrial insects were
not considered hi this opinion. Reasonable and Prudent Alternatives (RPAs) were given for each
jeopardized species. Reasonable and Prudent Measures (RPMs) were also given for 35 non-
jeopardized species to minimize incidental take of these species.  However, the consultations and
findings expressed in the two USFWS  Opinions are based on old  labels and application methods,
less refined risk assessment procedures, and an older approach to consultation, which is currently
being revised through interagency collaboration.

       EPA's current assessment of ecological risks uses both more refined methods to define
ecological risks of pesticides and new data, such as that for spray drift. Therefore, the RPAs and
RPMs in the Biological Opinion(s) may need to be reassessed and modified based on these new
approaches.

       The Agency is currently engaged in a Proactive Conservation Review with FWS and the
National Marine Fisheries Service under section 7(a)(l) of the Endangered Species Act. The
objective of this review is to clarify and develop consistent processes  for endangered species risk
assessments and consultations. Subsequent to the completion of this process, the Agency will
reassess the potential effects of disulfoton use to Federally listed threatened and endangered
species. At that time, the Agency will  also consider any regulatory changes recommended in the
IRED that are being implemented. Until; such time as this analysis is completed, the overall
environmental effects mitigation strategy articulated in this document will serve as interim
protection measures to reduce the likelihood that endangered and threatened species may be
exposed to disulfoton at levels of concern.

       Recently, the Agency completed a comprehensive preliminary assessment for potential
risk to endangered birds and mammals from disulfoton use.  Because risks to aquatic species
were addressed in the 1989 Biological  Opinion, they were not addressed in this assessment. To
conduct this assessment, the Agency used information from the Agency's OPP Endangered
                                           45

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r
                   Species database, which compares the USDA's Agriculture Census information on crop and
                   county overlap with USFWS information on the location of endangered species to the county
                   level. The results of this assessment are described in detail in the following documents:
                   Endangered Species Addendum to EFED's Disulfoton Science Chapter, dated January 24, 2002,
                   and Puerto Rican Plain Pigeon and Disulfoton, dated April 23, 2002. This document is
                   available in the public docket and on the internet. This comparison included the use sites and
                   regions identified below, because they comprise the majority of soil surface or foliar use of
                   disulfoton that could potentially affect endangered species that are exposed to such applications.
                   For purposes of endangered and threatened species evaluations, risks below EPA's  criteria of
                   concern are considered to be a "no effect." Therefore, a finding of "no concern for risk" is
                   equivalent to a "no effect" for the species.

                                 Asparagus— foliar application of liquid in CA and WA
                                 Barley - foliar application of liquid in CO, ID, MT and WA
                          •      Christmas trees — spot broadcast of granular in NC
                                 Coffee — spot broadcast of granular in Puerto Rico
                                 Cotton — m-furrow application of granular and liquid in LA, MO, OK, NC and
                                 SC
                          •      Potatoes — foliar application of liquid in ID and WA
                                 Wheat — foliar application of liquid in KY

                          The results of a screen of this information and other correspondence are as follows:

                   •      Puerto Rico has no endangered mammals; however, two endangered ground feeding
                          birds, the Yellow shouldered blackbird and Puerto Rican plain pigeon, could potentially
                          consume granules as grit. The Agency's screening level analysis indicated that the Puerto
                          Rican plain pigeon once lived in municipalities where coffee was grown. This is no
                          longer the case.  At present, neither of these avian species utilize coffee plantations for
                          habitat or occur near coffee plantations.  Therefore, there is no concern for risk for these
                          two species.

                   •      Concerning disulfoton use on barley, only the Mountain plover (a species that is not
                          currently listed as endangered, but is proposed to be listed) would be potentially at risk
                          from ingesting soil invertebrates in soil that has been sprayed directly or received wash
                          off from the foliage.  However, the residues would likely be lower on these soil
                          invertebrates than what would be required to cause an adverse effect in the Mountain
                          plover. Like other plovers, the Mountain plover prefers unvegetated, open areas;
                          therefore, if the barley is taller than 3 inches before it is sprayed, there is little likelihood
                          the bird would utilize the field.  Since disulfoton is. not used until later in the growing
                          season, after the plants are taller, it is exceedingly unlikely that Mountain plovers will be
                          utilizing  the treated fields. Therefore, there is no concern for risk to Mountain plovers.
                          There are 14 counties in Colorado and 17 counties in Montana where both barley is
                          grown and the bird may occur.
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There is no county overlap between asparagus grown in Washington and California, and
endangered species.

Carnivorous birds (i.e., owls and eagles) and mammals (i.e., Black-footed ferret, grizzly,
Gray wolf and Red wolf) are not at risk, based on secondary poisoning studies on
representatives from these two classes.  Therefore, there is no concern for risk to these
species.

Bats would not be  at risk as they would only be feeding on flying insects from dusk to
dawn.  Assuming spraying does not occur at those times, bats would not be at risk.  Also,
bats would not be exposed to granules.

Concerning Christmas trees grown in North Carolina, in addition to some of the
organisms stated above, there are several birds and mammals which, although they could
be in or around the vicinity of Christmas tree plantations, are not considered at risk
especially from granules. Specifically, because the Wood stork feeds on fish, and the
Piping plover resides on sand bars and feeds on aquatic invertebrates, there is no concern
for risk to these species.

Concerning Christmas trees grown in North Carolina, because disulfoton is systemic,
there is a slight potential for low, undetermined dietary exposure to the Northern flying
squirrel and the Red-cockaded woodpecker.  In addition to lichens and fungi, the squirrel
consumes insects,  buds, and seeds. However as the squirrel is a cavity nester, it prefers
deciduous trees to conifers in the same proximity. Its habitat is taller trees, because it has
adapted to gliding. The woodpecker requires old living pine trees (at least 60 years) in
which to make cavities, and they feed on insects found under the bark in conifers where
the trunk is larger  and more accessible than in Christmas trees. Therefore, disulfoton use
poses no concern for risk to these species.

Concerning use  sites other than Christmas trees and coffee, the following are forest
dwellers and/or are not associated with agricultural sites: Northern Idaho Ground
squirrel; Marbled murrelet (feeds on fish); Woodland caribou; Brown pelican (feeds on
fish); Red-cockaded woodpecker; Carolina northern flying squirrel; Treble's meadow
jumping mouse (resides in high elevation meadows); and Wood stork (feeds on fish).
Hence, disulfoton  use poses no concern for risk to these species.

Concerning the use sites other than Christmas trees and coffee, disulfoton poses no
concern for risk to the following species: the Whooping crane feeds on aquatic
invertebrates; the Black capped vireo resides in scrub areas and feeds  on flying insects;
and the Piping plover resides principally on sand bars and feeds on aquatic invertebrates.

              g.     Ecological Incident Reports

Several reports of wildlife poisonings are associated with disulfoton.  These poisoning
                                     47

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 incidents are summarized in Table 13.
 Table 13.  Chronological List of Ecological Incidents for Disulfoton
Date
6/12/95
6/14/94
1/24/94
6/18/93
6/22/91
4/26/91
Misuse?
unknown
unknown
unknown
No
unknown
unknown
Incident Description
Johnston County, NC: Fish kill occurred in commercial fish pond. Crop fields nearby
treated with pesticides. Water, soil and vegetation samples analyzed for a variety of
pesticides. Disulfoton, as well as several other pesticides, was found at 0.2-2.5 ppm in
vegetation samples. Possible certainty index for disulfoton. (Incident Report No.
1003826-002).
Arapahoe, CO: Fish kill following application of Di-Syston EC to wheat just before
heavy rain. Water samples contained disulfoton sulfoxide at 29.5-48.7 ppb and
disulfoton sulfone at 0.0199-0.214 ppb. (Incident Report No. 1001 167r001).
Puerto Rico: 6 grackles fell dead from a tree in a yard of private residence. Dead heron
and owl also found in vicinity. Use site and method not reported. Birds had depressed
acetyl cholinesterase. Analysis of GI contents of a grackles showed disulfoton at 2.37
ppm wet weight. Highly probable certainty index for disulfoton. (Incident Report No.
1003966-004).
Young County,TX: 1 8 Swainsons hawks dead, 1 severely disabled in a cotton field.
Cotton seed had been treated with disulfoton prior to planting, -10 days before the birds
were discovered. No additional applications of OP or carbamate pesticides made in
vicinity of field. Autopsies showed no trauma or disease. Lab analysis showed insect
material in GI tracts; this material contained disulfoton (~7 ppm); no other OP or
carbamate insecticides were present. Hawks fed on insects, which had been feeding on
the young cotton plants, which contained disulfoton residues. (L. Lybn, Div. of
Environmental Contaminants, U.S. Fish and Wildlife Service, Arlington, VA.)
Onslow County, NC: Fish kill in pond at private residence. Pond received runoff from
neighboring tobacco field; pondwater analysis showed disulfoton and several other
pesticides, including endosulfan. Disulfoton sulfoxide found in water at 0.32 ppb.
Endosulfan had highest concentration (1.2 (tg/L), and is toxic to fish, but disulfoton
cannot be ruled out as a possible cause of death. No tissue analysis. Possible certainty
index for disulfoton. (Incident Report No. B00002 1 6-025).
Sussex County, DE: 9 American robins dead following application of granular
disulfoton at tree nursery. Corn and soybeans also in vicinity. No laboratory analysis.
Probable certainty index for disulfoton. (Incident Report No. 1000 1 16-003).
       c.
Alternatives and Benefits
              1.
       Alternatives
       Only a limited number of alternative pesticides are available for controlling aphids on
agricultural crops. Some pesticides, such as lambda-cyhalothrin have some potential as a
disulfoton alternative; however, they also act on beneficial, predatory insects as well as targeted
insect pests, and can not be used in Integrated Pest Management (IPM) Programs.  Disulfoton
can be used in IPM programs because its systemic activity does not target beneficial insects. In
addition, lambda-cyhalothrin is a member of the chemical group synthetic pyrethroids, which are
prone to resistance problems. Imidacloprid is a potential alternative when used at-plant for
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short-lived crops, but this chemical loses its efficacy after 4-5 weeks. Also, imidacloprid is
currently more expensive than disulfoton.  Other alternatives are other OPs which are also under
review. Alternatives for crops representing primary uses are summarized in Table 14.

Table 14.  Registered Alternatives to Disulfoton for Agricultural Crops*
Crop/Target Pest
Asparagus/European Asparagus Aphid
Barley/Russian Wheat Aphid, other
aphids and thrips
Cotton/Thrips
Lima Beans/Thrips
Snap Beans/Potato Leafhopper, Thrips
Broccoli, Cabbage, Cauliflower &
Brussel Sprouts/Cabbage Aphid, other
aphids
Bell and Chili Peppers/Green Peach
Aphid, Symphylan
Lettuce/Lettuce Root Aphid
Potatoes/Green Peach Aphid, Potato
Aphid
Radish (grown for seed)/Cabbage Aphid,
Turnip Aphid
Wheat/Russian Wheat Aphid
Ornamentals, including shrubs, trees,
flowers, groundcover, and potted plants
(field or nursery stock)
Coffee Trees/Leafrniner
Christmas Trees (Firs)
Alternative Pesticide (Chemical Class)
Chlorpyrifos and dimethoate (OPs)
Imidacloprid (Chloronicotinyl), Lambda cyhalothrin (Synthetic
pyrethroid, Section 3 registration pending) • - •
Phorate, Aldicarb (OPs)
Acephate (OP)
Carbaryl (carbamate), acephate, methomyl, or dimethoate (OPs)
Chlorpyrifos, Dimethoate, Oxydemeton-methyl (OPs), Imidacloprid
(Chloronicotinyl)
Chlorpyrifos, Diazinon, Dimethoate, Malathion, Oxydemeton-
methyl (OPs), Imidacloprid (Chloronicotinyl), Pyrethroids
Imidacloprid (Chloronicotinyl)
Methamidophos, Dimethoate, Malathion (OPs), Pymetrozine
(Triazine), Imidacloprid, Thiomethoxam (Chloronicotinyls)
Pirimicarb (Carbamate), Chlorpyrifos (OP), Pymetrozine (Triazine)
Chlorpyrifos, Dimethoate, Malathion, Phorate (OPs), Endosulfan
(chlorinated hydrocarbon), Imidacloprid (Chloronicotinyl),
Lambda-cyhalothrin (Synthetic pyrethroid), Methomyl (carbamate),
Pyrethrins
Imidacloprid, Hexythiazox, Bifenazate, Abamectin, Acephate,
Chlorpyrifos (OP), Bifenthrin
Aldicarb, Azadirachtin (no residual activity)
Chlorpyrifos (OP)
* Not all alternatives are efficacious; see the following text for details.

              2.      Benefits

       The Agency has assessed the benefits of a number of registered uses of disulfoton,
including asparagus, barley and wheat, snap and lima beans, cabbage, cole crops, cotton, lettuce,
peanuts, peppers, potatoes, radish grown for seed, coffee, ornamentals, and Christmas trees.
Because occupation risks were low for disulfoton use on clover grown for seed, benefits
                                            49

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information associated with this use was not collected. A summary of the Agency's benefits
findings is presented below; for more information, see the following documents: Asparagus
Benefits Assessment for Disulfoton, September 11, 2001; Benefits ofDisulfoton on Selected
Vegetable Crops and Cotton, September 27, 2001; Benefits Assessment for Disulfoton Use on
Potatoes and Radish Seed, September 28, 2001; Use ofDisulfoton on Bell and Pimento Peppers,
November 3, 2001; Cursory Assessment ofDisulfoton Use in Coffee in Puerto Rico, November
26, 2001; Response to Questions Concerning Disulfoton Posed by Special Review and
Reregistration Division [Regarding Ornamentals], December  17, 2001; and Cursory Analysis of
Disulfoton Use on Fraser Fir Christmas Trees in Western North Carolina, July 9, 2002. All of
these documents are available in the public docket and on the internet.

       Asparagus

       Liquid disulfoton is used on asparagus in Arizona, California, North Carolina, Oregon,
and Washington. These states have  Special Local Need (SLN) registrations under FIFRA
Section 24(c). Most disulfoton use on asparagus is in California and Washington; these two
states account for 96% of use on this crop. In Washington, 50% of the asparagus crop is treated
with disulfoton, and in California, 70% of the crop is treated. Growers in these states have a
critical need for Di-Syston 8E. The  target pest is the European asparagus aphid, which severely
damages  asparagus plants and weakens the crowns.  Asparagus is a high value perennial crop
grown for 10 years or more. The asparagus plants rely on energy produced by vegetative growth
and stored in the root crowns to produce the shoots that are harvested the following year.
Registered pesticide alternatives are chlorpyrifos and dimethoate, but secondary aphid flare ups
occur with chlorpyrifos, and both chlorpyrifos and dimethoate  have a short residual half-life.
Therefore, none of these alternatives is considered viable. Disulfoton is long lived and spares
beneficial insects, preventing secondary flare ups of insect pests.

       Disulfoton is applied once or twice a year during the fern stage (after harvest) at a rate of
2 Ib ai/A. At this point in the asparagus life cycle, there are no activities (other than pest control)
requiring the presence of workers in the fields. Vegetation is up to 5 feet high and wide at this
stage of the life cycle, so the rows are virtually impassible.  Growers have difficulty getting
application equipment into the fields and aerial application  is the most feasible method of
pesticide application at this stage. The liquid formulation is needed because of its translaminar
action; liquid is quickly taken up by foliage where it penetrates the outermost cell layers and
spreads out, providing aphid control. Even though the granular also has systemic action, it is not
taken up by asparagus roots quickly  enough to control aphids.  Therefore, the granular
formulation is not registered for use on asparagus.

       In Washington, 98% of disulfoton used on asparagus is applied aerially for the reason
stated above. In California, 65% of disulfoton is applied aerially. The remaining 35% of
disulfoton used on asparagus in California is applied by groundboom to the field edges to stave
off aphid infestation. Based on the 1977 Agriculture Census from the USD A National
Agricultural Statistics Service (NASS), the overall average  asparagus farm size in California is
219 acres. Also, for asparagus farms in Washington, no farm is greater than 300 acres, and the
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average asparagus farm size is 62 acres.  Other sources indicate that the maximum area that can
be aerially treated in a day is about 75-150 acres in Washington, and about 150-200 acres in
California.

       Barley and Wlieat

       Liquid disulfoton is applied by air for late-season control of aphids on barley and wheat
as the seed head nears maturity. Nationally, < 1% of crop is treated for both barley and wheat,
with most use on malting barley in the states of Idaho, Montana, Colorado, Wyoming, and
Washington. Disulfoton use on wheat is limited to a few states, where Kentucky is reported to
have the greatest use.  The potential alternative for aphid control on these crops is lambda
cyhalothrin (Warrior®), which is scheduled for a FIFRA Section 3 registration in 2002.
Warrior® is already available in some states as a FIFRA Section 18 registration. There are
concerns that, because Warrior® is a pyrethroid, aphids may develop resistence, and a secondary
control for resistance .management may be needed.

       Nearly 50% of all barley produced in the US is marketed as malting barley, which
receives a premium price over regular barley.  Disulfoton is used primarily on malting barley to
control aphids, especially the Russian wheat aphid, to ensure plumpness and fullness of the
barley grain. Aphid infestations in barley fields are localized and sporadic, and require
immediate control to prevent spreading. Aphid damage to malting barley can result in up to a
50% loss in crop revenue. Approximately 3% of all acres planted in barley experience aphid
infestation. In these cases, the liquid formulation of disulfoton is  generally applied aerially to
localized pockets of aphid infestation. Imidacloprid is registered for late-season control aphids
in malting barley, but does not appear to be as effective as disulfoton in controlling aphids by
foliar application. However, lambda cyhalothrin (Warrior®), which is  expected to be available
as a Section 3 registration within the next year, is considered to be the product of choice, because
it is recognized as a safer alternative to disulfoton, especially for aerial  application due to drift
concerns to nearby inhabited areas and adjacent fields. Disulfoton use  has been declining in
recent years due to the use of Warrior® as the primary tool for aphid control in the states where
it is currently used under FIFRA Section 18 registrations.

       Disulfoton is used on wheat to control the Barley Yellow Dwarf Virus, which is
transmitted by aphids. Ground applications of the liquid are used late-season. In Kentucky, the
state with the greatest use, most disulfoton is applied by custom applicators. Lambda
cyhalothrin is the main alternative for wheat, which may be more expensive than disulfoton.
Other registered alternatives include chlorpyrifos, malathion, methomyl, and pyrethrins.

       Beans, Lima and Snap

       Growers use both liquid and granular formulations of disulfoton for lima and snap beans.
Most use on lima beans-is in Georgia, with 20-30% of crop treated. Disulfoton is applied at-
plant to control thrips. Acephate is  currently the only viable alternative for lima beans, and
foliar application would be used to control thrips.
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       Use on snap beans is sporadic in states that produce snap beans and use is declining.
Disulfoton is applied at-plant to control potato leaf hopper, an intermittent pest that does not
require control every year.  Some processing companies will not purchase snap beans treated
with a systemic insecticide unless a pest problem requiring such treatment is substantiated by
extension agents. Alternatives to disulfoton on snap beans include acephate, carbaryl,
methomyl, or dimethoate.

       Cabbage

       Both the liquid and granular formulations are registered for use on cabbage for aphid
control. The liquid formulation is shank injected, and the granular formulation is applied as a
soil incorporated band or side-dressing. According to USDA NASS data for 2000, 3,400 Ib ai of
disulfoton was applied that year, with 3% of all cabbage grown nationally being treated with
disulfoton In California, from 1997 to 1999, an average of 3,117 Ibs ai of disulfoton was
applied to cabbage, primarily in Ventura County. The major advantage of disulfoton over
imidacloprid is its long residual activity, which protects cabbage plants for the entire season.

       Cole Crops  (Broccoli, Brussels Sprouts, Cauliflower)

       Both the liquid and  granular formulations of disulfoton are registered for use on cole
crops. The liquid formulation is used exclusively in California's Salinas Valley, whereas the
granular formulation is used nationally, wherever cole crops are grown.  Liquid disulfoton is
applied by shank injection,  and is used as a rescue remedy to control cabbage and green peach
aphids. Within the Salinas Valley, Monterey County appears to be where the predominant use of
the liquid formulation of disulfoton is used. Usage data from 1997 to 1999 for Monterey
County, California indicate that as much as 60%  of broccoli, 87% of Brussels sprouts, and 52%
of cauliflower that was grown was treated with disulfoton. Nationally, less than 3% of the crop
was  treated in 2000.

       Registered alternatives to disulfoton on cole crops include imidacloprid and the  OP
pesticides oxydemeton-methyl, dimethoate, and chlorpyrifos.  Currently, imidacloprid is applied
at-plant, but it does not control the cabbage aphid throughout the entire growing season due to its
limited period of residual effectiveness. Imidacloprid is not effective as a foliar application.
Chlorpyrifos is toxic to beneficial insects and also causes phytotdxicity at the high rates required
to control the cabbage aphid.

       Cotton

       Liquid disulfoton is used as a safener to protect cotton seedlings from the effects of the
herbicide clomazone (Command®), which is the  herbicide of choice to control velvet leaf,
primrose, morning glory, and wild poinsettia. The liquid formulation is preferred, because it
appears to be both a better safener and more effective than the granular formulation at protecting
the cotton seedlings against thrips. Alternatives include phorate and aldicarb.  However,
phorate, which is applied as a granular formulation, is not as efficacious against thrips.  Aldicarb
                                            52

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is very effective against thrips, but does not act as a safener.

       Use of disulfoton in cotton has been declining and this decline has been attributed to the
introduction of genetically modified glyphosate tolerant (RoundUp-Ready®) cotton. However,
the percentage of acreage that can be planted with glyphosate tolerant cotton is limited.
Therefore, disulfoton is still important in areas that use clomazone for weed control.  Most use is
in Louisiana, Missouri, Mississippi, and Texas, with some use in Alabama, Arkansas, Georgia,
Florida, Tennessee, the Carolinas, and Virginia.

       Lettuce

       Only the liquid formulation of disulfoton is registered for use on lettuce.  Disulfoton is
applied preplanting or at planting by banding, sometimes in combination with fertilizer or
herbicide. Most iceberg lettuce (96%) and leaf lettuce (97%) grown in the United States is
produced in California and Arizona. California treated about 2-3% of the iceberg and 1% of the
leaf lettuce acreage with disulfoton hi 1999. USDA reported no use of disulfoton in Arizona for
the year 2000.                            ,

       Disulfoton use on lettuce in California is mostly limited to the Salinas Valley, which
includes Monterey County. Approximately 59% of the total amount of disulfoton that is used on
head lettuce is used in Monterey County, and 57% of the total amount of disulfoton that is used
on leaf lettuce is also used in Monterey  County.  Disulfoton is used in this area primarily  to
control the lettuce root aphid, which is harbored in Lombardy poplars, a popular ornamental,
when other methods fail.  California has been actively removing Lombardy poplar trees so that
the lettuce root aphid does not have an alternate host. If disulfoton is not used, the main
pesticide alternative is imidacloprid, which has short residual activity and therefore  does not
provide adequate control.

       Peanuts

       Only the granular formulation is registered on peanuts.  Thrips are the main target pest,
but disulfoton is also used for aphid control. In the year 2000,  disulfoton was used in Alabama,
Georgia, North Carolina, and Oklahoma. Disulfoton is applied in-furrow or as a soil
incorporated side-dressing to control thrips and aphids. Since the time the risk assessment was
prepared, Bayer, the technical registrant, had reduced the maximum application rate for the
Section 3 registration from 2 Ibs ai/A to 1 Ib ai/A.  Disulfoton is applied once a year at a rate of 1
Ib ai/A, except in North Carolina where an SLN registration permits two applications for  a
seasonal maximum of 2 Ibs ai/A.

       Peppers

       Disulfoton is used on chili, bell, and pimento peppers to control the green peach aphid
and the garden symphylan, a non-insect pest. Most disulfoton use on peppers is in California
and New Mexico.  Aphids, especially the green peach aphid, transmit mosaic viruses which kill
                                           53

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pepper plants. The green peach aphid has developed insecticide resistance and is difficult to
manage. The green peach aphid prefers shade-grown plants, such as those in the Salinas Valley.

       Both liquid and granular formulations are registered for use on peppers.  The liquid
formulation is registered only in California as a Section 24(c) SLN registration.  The liquid is
shank injected when the plants are 4-5 weeks old and the aphids have exceeded the economic
threshold. There is a FIFRA Section 3 registration for the granular, which is used outside
California.

       Registered alternatives to disulfoton on peppers include irnidacloprid, chlorpyrifos,
diazinon, dimethoate, malathion, oxydemeton methyl, and pyrethrins.  Neither diazinon nor
malathion is effective against the green peach aphid. Dimethoate is an inexpensive, frequently
used alternative, but it is no longer effective for aphid control in some areas of California and
New Mexico. Chlorpyrifos harms beneficial insects and has been shown to cause phytotoxicity
at the rates necessary for  aphid control. Although oxydemeton methyl is registered, it is not
recommended for use on  cole crops. Use of irnidacloprid is increasing, but it does not provide
effective control in some parts of California.  Pyrethroids are not often used because they are not
compatible with integrated pest management (IPM) programs.

       Potatoes

       Both the liquid and granular formulations of disulfoton are registered for use on potatoes
to control aphids. Based on 1987-1998 usage data, an average of approximately 58,000 acres of
potatoes were treated annually, with an average of 4% of the nations potato acreage treated with
disulfoton. The liquid is  used mainly in the Pacific Northwest (PNW) (i.e., Oregon, Idaho,
Washington, and Utah), where it is predominantly applied either aerially or by chemigation
(sprinkler irrigation) as an alternative to methamidophos (Monitor®).  The liquid is used for late-
season aphids control in sensitive areas where growers cannot aerially apply Monitor®.  The
granular formulation appears to be used mostly outside the PNW, where it is applied to the soil
and incorporated.

       As mentioned above, the liquid formulation is applied in the PNW by overhead sprinkler
irrigation to control aphids.  According to the National Potato Council, growers apply disulfoton
by chemigation (sprinkler irrigation) when methamidophos (Monitor®), the product of choice,
cannot be aerially applied, due to weather conditions or lack of availability of aerial applicators,
or for potatoes that are grown next to sensitive areas, where aerial application is an issue.
However, the Agency believes that there are a number of other alternative products that are
available'to control aphids that can be chemigated, such as pymetrozine (Fulfill) and
thiamethoxam  (Actara), which seem promising, although growers are learning how to use these
new chemistries. Further, methamidophos is labeled for application by chemigation.
Imidacloprid can also be applied at-plant for control of early to mid season aphid and Colorado
potato beetle infestations.

       Although growers may view disulfoton as the only cost-effective, reliable, and consistent
                                            54

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aphid material that can be chemigated, the Agency believes the available alternatives are
adequate to achieve effective aphid control. Both pymetrozine and thiomethoxam can be applied
by chemigation and are effective at late-season aphid control.  Further, pymetrozine is less
expensive than disulfoton. The average cost of post-emergence foliar treatment for potatoes is
about $16.00 per acre for disulfoton and $13.00 per acre for pymetrozine. No data were
available for thiomethoxam. Because these two chemicals are relatively new, they have yet to be
widely used or accepted by growers; however, efficacy field trials show promising results for
aphid control.

       In summary, the Agency does not believe that disulfoton is critical to potato growers,
because use of disulfoton on potatoes is declining and new, effective alternatives that can be
applied by chemigation, the application method that is most critical to growers in the PNW, are
now available.

       Radish Grown for Seed

       Both the  liquid and granular formulations are registered for use on radish grown for seed
in Washington only through a 24(c) SLN registration. As part of this registration, disulfoton use
is limited to the Columbia River Basin in Washington to control cabbage and turnip aphids,
which cause premature plant death and crop loss. Both formulations are applied to the soil and
are either shank injected or soil incorporated. In the year 2000, only about 635 acres total of this
crop was produced. Even though it is a minor crop, it is an economically important crop for
producers in the  Columbia River Basin.

       The only registered alternatives available to growers are pirimicarb, chlorpyrifos, and
pymetrozine. Pirimicarb is used solely to control late-season aphid infestations; chlorpyrifos
cannot be used during bloom when aphids can occur; and pymetrozine is more expensive than
disulfoton and does not provide good lower canopy control. Also, disulfoton is  also
advantageous because it allows predatory and parasitic insects to develop in the seed radish
fields.

       Coffee Trees

       Granular disulfoton is registered in Puerto Rico to control leafminers, which can cause
up to a 40% reduction in yield in the coffee crop, valued at approximately $30 million.  In the
year 2000, about 15% of acreage planted in coffee was treated with disulfoton. The current
application rate of 8.3 Ibs a.i./A is supported by efficacy data.  Government sponsored custom
applicators broadcast disulfoton by hand, with a bucket and spoon. Growers and agricultural
extension staff appear to be receptive to alternative application methods involving closed
systems.  At present, the only viable alternative is aldicarb. Azadirachtin, a registered
alternative, does  not have the residual activity needed to control leafminers.
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       Christinas Trees

       DIsulfoton is used on Christmas trees, on Fraser, Balsam, and other firs, in 16 states
including Oregon, Michigan, Washington, Ohio, and Wisconsin. The greatest use is in western
North Carolina, where 1,600 growers produced 34-million trees on 24,000 acres in 1996.  Two-
thirds of North Carolina Christmas tree farms are small, with 10 acres or less in production.

       Disulfoton is used to control balsam twig aphid and spruce spider mite, widespread and
perennial pests. Disulfoton is used in conjunction with chlorpyrifos and esfenvalerate.
Disulfoton is applied at bud break in early spring, followed by foliar applications of chlorpyrifos
and'esfenvalerate.  Disulfoton and esfenvalerate may be alternated if resistance management
becomes an issue.  Chlorpyrifos and esfenvalerate must be foliarly-applied by a commercial
applicator by mist blower or high-powered hose sprayer. Further, the chlorpyrifos foliar spray is
phytotoxic in some situations.  Foliar applications are problematic, because they are usually
uneven, which significantly affects efficacy. Esfenvalerate has the advantage of also controlling
balsam wooly adelgid to a limited extent, but the disadvantage of allowing spider mite
populations to increase.  Disulfoton control of both balsam twig aphid and spruce spider rnite is
systemic, conserving beneficial insect predators.

       Christmas trees are a perennial crop with a 6-10 year growth cycle. The target pests can
cause significant cosmetic damage in the last year or two before harvest, leading to a significant
decrease in crop value and/or crop loss.  Value was $78 million in 1996 and $122 million in
1999.  Fraser firs represented 27% of all US grown Christmas trees sold in 1999.  Impacts are
greatest near harvest when trees may be downgraded for cosmetic damage. Without disulfoton,
a significant amount of loss from downgrading and extra application costs would be sustained
over the region annually. Disulfoton is important in resistance management and conserving
beneficial insects.  Disulfoton is an important component of the Fraser fir integrated pest
management (IPM) program developed by the North Carolina Agricultural Extension Service
and North Carolina State University.  The Agency concludes that disulfoton use on Christmas
trees, especially Fraser firs  grown in the mountains of western North Carolina, is critical to
growers.

       Commercially Grown Ornamentals

       The granular formulation is registered for use on shrubs, trees, flowers, and ground
covers (field or nursery stock) to control a variety of pests, including aphids, thrips, lacebugs,
and mites. The current label rate is up to 7.5 grams per foot of shrub height or 2.5 oz per trunk
diameter of trees, which is extrapolated to 109 Ibs ai/A. The nursery industry claims to need a
ininimurn rate of 13 Ibs ai/A; however, EPA can not substantiate this rate for all uses. Available
data show use of ^6 Ibs ai/A in California and 13 Ibs ai/A on hollies and birches in New York,
with 2% of the production area treated. Disulfoton is applied by broadcast or soil injection.
According to preliminary data from a USD A NASS floriculture survey, very little disulfoton is
used on ornamentals. Of 4,000 operations surveyed, only 22 operations reported using
disulfoton. After extensive research and contacting all major stakeholders, including the
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American Nursery and Landscape Association, Rutgers's IR4, and state departments of
agriculture, EPA has found only small pockets of use. Further, many agricultural extension
agents who work with ornamentals do not recommend the use of disulfoton. Alternatives are
available, including imidacloprid, abamectin, aeephate, bifenthrin, and chlorpyrifos.  Therefore,
the Agency concludes that on a national basis, there is not a critical need for disulfoton use on
ornamentals grown for field or nursery stock.
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IV.    Interim Risk Management and Reregistration Decision

       A.     Determination of Interim Reregistration Eligibility

       Section 4(g)(2)(A) of FIFRA calls for the Agency to determine, after submissions of
relevant data concerning an active ingredient, whether products containing the active ingredient
are eligible for reregistration. The Agency has previously identified and required the submission
of the generic (i.e., an active ingredient specific) data required to support reregistration of
products containing disulfoton active ingredient.                                        '

       The Agency has completed its assessment of the occupational and ecological risks
associated with the use of pesticides containing the active ingredient disulfoton, as well as a
disulfoton-specific dietary risk assessment that has not considered the cumulative effects of OPs
as a class. Based on a review of these data and public comments on the Agency's assessments
for the active ingredient disulfoton, EPA has sufficient information on the human health and
ecological effects of disulfoton to make interim decisions  as part of the tolerance reassessment
process under FFDCA and reregistration under FIFRA, as amended by FQPA. The Agency has
determined that products containing disulfoton are eligible for reregistration provided that (i)
current data gaps and additional data needs are addressed; (ii) the risk mitigation measures
outlined in this document are adopted, and label amendments are made to reflect these measures,
including the phase out of disulfoton use on barley, wheat, potatoes, and ornamentals by June
2005; (iii) cumulative risks  considered for the OPs support a final reregistration eligibility
decision; and tolerances are issued (if appropriate) for commodities lacking tolerances as
identified in the tolerance summary.

       As part of the Agency's ongoing process to review and take the necessary risk reduction
measures as required by FQPA, on December 4, 2001, EPA released the preliminary cumulative
risk assessment for OP pesticides for public comment. That assessment is based on evaluation of
the potential exposure of 31 total OP pesticides from eating food, drinking water, and residential
sources.  The assessment also takes into account EPA's past regulatory actions on various
pesticides, such as eliminating uses. Continuing the effort to ensure transparency of decision
processes, EPA conducted a technical briefing and presented the assessment to the Scientific
Advisory Panel for peer review and comment.  The Agency intends to release a revised
cumulative risk assessment during the summer of 2002.

       Although the Agency has not yet considered its final cumulative risk assessment for the
OPs, the Agency is issuing this interim decision now in order to identify risk reduction measures
that are necessary to support continued use of disulfoton. Based on its current evaluation of
disulfoton alone, the Agency has determined that disulfoton products, unless labeled and used as
specified in this document, would present risks inconsistent with FIFRA.  Accordingly, should a
registrant fail to implement any of the risk mitigation measures identified hi this document, the
Agency may take regulatory action to address the risk concerns from use  of disulfoton.

       At the time that the cumulative assessment is considered, the Agency will address any
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outstanding risk concerns.  For disulfoton, if all changes outlined in this document are
incorporated into the labels, then all currently identified risks will be mitigated. But, because
this is an IRED, the Agency may take further actions, if warranted, to finalize the RED for
disulfoton after considering the cumulative risk of the OP class. Such an incremental approach
to the reregistration process is consistent with the Agency's goal of improving the transparency
of the reregistration and tolerance reassessment processes. By evaluating each OP pesticide in
turn and identifying appropriate risk reduction measures, the Agency is addressing the risks from
the OPs in as timely a manner as possible.

       Because the Agency has not yet considered the cumulative risks  for the OPs, this IRED
does not fully satisfy the reassessment requirement for existing disulfoton food residue
tolerances as called for by FQPA. When the Agency has considered cumulative risks, disulfoton
tolerances will be reassessed in that light. At that time, the Agency will reassess disulfoton
along with the other OP pesticides to complete the FQPA requirements and make a final
reregistration eligibility determination. By publishing this IRED and requesting mitigation
measures now for the individual chemical disulfoton, the Agency is not  deferring or postponing
FQPA requirements; rather, EPA is taking steps to assure that uses which exceed FIFRA's
unreasonable risk standard do not remain on the label indefinitely, pending completion of an
assessment required under the FQPA. This  decision does not preclude the Agency from making
further FIFRA or FQPA determinations and tolerance-related ralemakings that may be required
on this pesticide or any other in the future. If the Agency determines, before finalizing the RED,
that any of the determinations described in this IRED are no longer appropriate, the Agency will
pursue appropriate  action, including but not limited to, reconsideration of any portion of this
IRED.

       Label changes for disulfoton are described in Section V. Appendix B identifies the
generic data the Agency reviewed as part of its IRED of disulfoton, and lists the studies that the
Agency found acceptable.

       B.     Summary of Phase 5 Comments

       When making its IRED for disulfoton, the Agency took into account all comments
received during Phase 5 of the OP Public Participation Process.  Comments were received from
the technical registrant, Bayer Corporation; the American Landscape and Nursery Association;
the California Asparagus Commission; the American Bird Conservancy; North Carolina
Cooperative Extension Service; and from numerous individual North Carolina Christmas tree
growers. A brief summary of the comments is provided below. All of the submitted comments
in their entirety are available in the public docket, and the Agency's response to the comments is
also available in the docket and on the internet.,

       A number of Christmas tree growers in North Carolina provided comments relating to
their use practices, farm sizes, the number of acres they treat with disulfoton, the frequency of
their applications, the number of workers involved in disulfoton application activities, and the
length of time it takes to make the pesticide  applications.  The Agency has validated much of this
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information and used it to revise the risk assessments for disulfoton.

       The North Carolina Cooperative Extension Service commented on both the worker and
ecological risks assessments for disulfoton and provided extensive information on disulfoton use,
cultural practices, and impacts of disulfoton on stream fauna. EPA has considered this
information in both the revised risk assessment and the regulatory decision for disulfoton.

       The American Nursery and Landscape Association commented on pest management
issues in the nursery industry.  Disulfoton allows nurserymen to use less pesticide overall
because disulfoton is compatible with Integrated Pest Management (IPM). The American
Nursery and Landscape Association urges EPA to allow time for  development of data to refine
the worker risk assessment. The California Asparagus Commission commented on the use of
disulfoton in asparagus and provided information about cultural practices. EPA has considered
information on integrated crop management, cultural practices, and feasibility of various
mitigation measures in its interim regulatory decision for disulfoton.

       The American Bird Conservancy recommended elimination of all aerial applications as
well as foliar sprays by ground equipment in wheat and sorghum. The American Bird
Conservancy also recommended use of a less friable non-clay based granular formulation.  EPA
has considered these suggestions in the risk mitigation strategy for disulfoton.

       Bayer Corporation, the technical registrant, provided comments that focused on further
refining assessed risks and potential risk mitigation measures for disulfoton. Bayer's efforts to
reduce risks include repackaging the liquid formulation into a closed mixing/loading system,
reformulating and repackaging the 1% granular home use product. EPA has considered all of
this new information in the revised risk assessment for disulfoton.

       C.    Regulatory Position

             1.     FQPA Assessment

                     a.     "Risk Cup" Determination

       As part of the FQPA tolerance reassessment process, EPA assessed the risks associated
with this OP. The assessment was for this individual OP, and does not attempt to fully reassess
these tolerances as required under FQPA.  FQPA requires the Agency to evaluate food
tolerances on the basis of cumulative risk from substances sharing a common mechanism of
toxicity, such as the toxicity expressed by the OPs through a common biochemical interaction
with the' cholinesterase enzyme. The Agency will evaluate the cumulative risk posed by the
entire class of OPs once the methodology is developed and the policy concerning cumulative
risks is resolved.

       EPA has determined that dietary risk from exposure to disulfoton is within its own. "risk
cup." In other words, if disulfoton did not share a common mechanism of toxicity with other
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 chemicals, EPA would be able to conclude today that the tolerances for disulfoton meet the
 FQPA safety standards, provided the risk mitigation measures outlined in this document are
 adopted and additional data needs are addressed. In reaching this determination EPA has
 considered the available information on the special sensitivity of infants and children, as well as
 the chronic and acute food exposure.  An aggregate assessment was conducted for exposures
 through food, residential uses, and drinking water.  Based on the results of this aggregate
 assessment, the Agency has determined that the human health risks from these combined
 exposures are considered to be within acceptable levels.  While the screening-level modeling
 estimates indicate that disulfoton may in fact fill its aggregate risk cup, the Agency has
 determined that actual drinking water exposures are likely lower than predicted by the model,
 and has made an interim determination that disulfoton does "fit" within the dietary risk cup.
 However, EPA will seek additional data to help refine and confirm this assessment.  Except for
 those tolerances that are to be lowered or revoked, the current disulfoton  tolerances will remain
 in effect and unchanged until a full reassessment of the cumulative risk from all OP pesticides is
 considered later this year.

                     b.     Tolerance Summary

       Tolerances for residues of disulfoton in/on plant commodities [40 CFR §180.183] are
 presently expressed in terms of the combined residues of disulfoton and its cholinesterase-
 inhibiting metabolites, calculated as demeton. The tolerance expression for disulfoton should be
 modified to include the combined residues of parent, the sulfoxide and sulfone degradates, and
 the oxygen analogues of the sulfoxide and sulfone degradates. Specifically, tolerances should be
 modified to include the combined residues of O,O-diethyl S-[2-(ethylthio)-ethyl]phosphoro-
 dithioate; O,O-diethyl S-[2-(ethylthio)-ethyl]phosphorothioate; O,O-diethyl S-[2-(ethylsulfmyl)-
 ethyl] phosphorodithioate; O,Q-diethyl S-[2-(ethylsulfinyl)-ethyl]phosphorothioate; O,O-diethyl
 S-[2-(ethylsulfonyl)-ethyl]phosphorodithioate; and O,O-diethyl S-[2-(ethylsulfonyl)-
 ethyl]phosphorothioate. The Agency is changing the tolerance expression to include all
 degradates of toxicological concern.

       The Agency will commence proceedings to  revoke and modify the existing tolerances,
 and correct commodity definitions. The establishment of a new tolerance or raising tolerances
 will be deferred, pending consideration of cumulative risk for the OPs.  "Reassessed" does not
 imply that all of the tolerances have been reassessed as required by FQPA, since these tolerances
 may only be reassessed once the cumulative risk assessment of all OP pesticides is considered,
 as required by the statute.  Rather, this IRED provides reassessed tolerances for disulfoton in/on
 various commodities,  supported by all of the submitted residue data, only for the single OP
 chemical disulfoton. EPA will finalize these tolerances after considering the cumulative risks for
 all OP pesticides.

       The Agency's tolerance summary is provided in Table 15.  This table lists several
tolerances associated with uses that are no longer registered, as announced in several FIFRA
6(f)(l) Notices of Receipt of Requests from the registrant for cancellation and/or use deletion,
which EPA approved. Therefore, the associated tolerances should be revoked.  This table also
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lists uses that are to be phased out and the associated tolerances that are to be revoked after 2004.
Last, this table lists livestock tolerances that must be established following consideration of the
cumulative assessment for all OPs.  Livestock feeding studies for disulfoton indicate that
residues transfer from feed to meat and milk; therefore, tolerances should be established for
livestock commodities, pending consideration of the cumulative assessment for all OPs.
Table 15. Tolerance Summary for Disulfoton _ _
Commodity

Barley, grain
Barley, straw
Beans, dry
Beans, lima
Beans, snap
Beans, vines
Beets, sugar, roots
Beets, sugar, tops
Broccoli
Brussels sprouts
Cabbage
Cattle, meat
Cattle, meat
byproducts
Cattle, fat
Cauliflower
Coffee beans
Current
Tolerance (ppm)
Reassessed1
Tolerance (ppm)
Comment/
[Correct Commodity Definition]
Tolerances Listed Under 40 CFR §180.183(a)(l)
Raw Agricultural Commodities
0.75
5.0
0.75
0.75
0.75
5.0
0.5 '
2.0
0.75
0.75
0.75
-
—
-
0.75
0.3
0.20
5.0
Revoke
0.75
0.75
Revoke
Revoke
Revoke
0.75.
0.75
0.75
0.05
0.05
0.05
0.75
0.2
Available data for wheat support lowering
barley tolerance. Wheat data may be
translated to barley. EPA expects to revoke
tolerance after the use is phased out;
however, tolerance should be lowered in the
interim.
EPA expects to revoke after the use is
phased out.
Use on dry beans deleted; therefore,
tolerance should be revoked.
[Bean, succulent]
[Cowpea, forage]
Use on cowpeas was deleted; therefore,
tolerance should be revoked.
No registered uses on sugar beets; therefore,
associated tolerances should be revoked.



Tolerance should be proposed based on
LOQ, pending outcome of OP cumulaitive
assessment.
Tolerance should be proposed based on
LOQ, pending outcome of OP cumulative
assessment.
Tolerance should be proposed based on
LOQ, pending outcome of OP cumulative
assessment.

[Coffee, bean, green] Available data support
lowering the tolerance.
                                             62

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Commodity
Com, field, fodder
Corn, field, forage
Com, grain
Corn, pop
Corn, pop, fodder
Corn, pop, forage
Com, sweet, fodder
Corn, sweet, forage
Corn, sweet, grain
(K+CWHR2)
Cottonseed
Goats, meat
Goats, meat
byproducts
Goats, fat
Hog, fat
Hog, meat
Hog, meat
byproducts
Hog, fat
Hops
Horse, meat'
Horse, meat
byproducts
Current
Tolerance (ppm)
5.0
5.0
0.3
0.3
5.0
5.0
5.0
5.0
0.3
0.75
~
- -
,
~
--'
-
-
0.5
.--
- -
Reassessed1
Tolerance (ppm)
Revoke
Revoke
Revoke
Revoke
Revoke
Revoke
Revoke
Revoke
Revoke
0.75
0.05
0.05
0.05
0.05
0.05
0.05
0.05
Revoke
0.05
0.05
Comment/
[Correct Commodity Definition]
Use on com deleted; therefore associated
tolerances should be revoked.


[Cotton, undelinted seed]
Tolerance should be proposed based on
LOQ, pending outcome of OP cumulative
assessment.
Tolerance should be proposed based on
LOQ, pending outcome of OP cumulative
assessment.
Tolerance should be proposed based on
LOQ, pending outcome of OP cumulative
assessment.
Tolerance should be proposed based on
LOQ, pending outcome of OP cumulative
assessment.
Tolerance should be proposed based on
LOQ, pending outcome of OP cumulative
assessment.
Tolerance should be proposed based on
LOQ, pending outcome of OP cumulative
assessment.
Tolerance should be proposed based on
LOQ, pending outcome of OP cumulative
assessment.
No registered uses on hops; therefore
tolerance should be revoked.
Tolerance should be proposed based on
LOQ, pending outcome of OP cumulative
assessment.
Tolerance should be proposed based on
LOQ, pending outcome of OP cumulative
assessment.
63

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Commodity
Horse, fat
Lettuce
Milk
Oats, fodder, green
Oats, grain
Oats, straw
Peanuts
Peas
Peas, vines
Pecans
Peppers
Pineapples
Potatoes
Rice
Rice, straw
Sheep, meat
Sheep, meat
byproducts
Current
Tolerance (ppm)
-
0.75
.--
5.0
0.75
5.0
0.75
0.75
5.0
0.75
0.1
0.75
0.75
0.75
5.0
-
-
Reassessed1
Tolerance (ppm)
0.05
0.75 head
TBD leaf3
0.01
Revoke
Revoke
Revoke
0.10
Revoke
Revoke
Revoke
0.10
Revoke.
0.50
Revoke
Revoke
0.05
0.05
Comment/
[Correct Commodity Definition]
Tolerance should be proposed based on
LOQ, pending outcome of OP cumulative
assessment.
[Lettuce, head]
[Lettuce, leaf] Tolerance to be raised for
leaf lettuce, pending completion of
additional field trial data and the outcome of
the OP cumulative assessment.
Tolerance should be proposed based on
LOQ, pending outcome of OP cumulative
assessment.
Use on oats deleted; therefore, associated
tolerances should be revoked.
Available data for peanuts support lowering
tolerance.
[Peanut]
Use on peas deleted; therefore, associated
tolerances should be revoked.
Use on pecans deleted; therefore, associated
tolerances should be revoked.
[Pepper, bell]
[Pepper, nonbell]
No registered uses on pineapple; therefore,
tolerance should be revoked.
[Potato] Available data for potatoes support
lowering tolerance. EPA expects to revoke
tolerance after the use is phased out;
however, tolerance should be lowered in the
interim.
No registered uses on rice; therefore,
tolerance was revoked.
Tolerance should be proposed based on
LOQ, pending outcome of OP cumulative
assessment.
Tolerance should be proposed based on
LOQ, pending outcome of OP cumulative
assessment.
64

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Commodity
Sheep, fat
Sorghum, fodder
Sorghum, forage
Sorghum, grain
Soybeans
Soybeans, forage
Soybeans, hay
Spinach
Sugarcane
Tomatoes
Wheat, fodder,
green
Wheat, grain
Wheat, straw
Current
Tolerance (ppm)
-
5.0
5.0
0.75
0.1
0.25
0.25
0.75
0.3
0.75
5.0
0.3
5.0
Reassessed1
Tolerance (ppm)
0.05
Revoke
Revoke
Revoke
Revoke
Revoke
Revoke
Revoke
Revoke
Revoke
5.0
0.2
5.0
Comment/
[Correct Commodity Definition]
Tolerance should be proposed based on
LOQ, pending outcome of OP cumulative
assessment.
Use on sorghum deleted; therefore,
associated tolerances should be revoked.

Use on soybeans deleted; therefore,
associated tolerances should be revoked.

No registered use on spinach; therefore,
tolerance should be revoked.
No registered use on sugarcane; therefore,
.tolerance should be revoked.
Use on tomatoes deleted; therefore,
tolerance should be revoked.
[Wheat, forage] EPA expects to revoke
tolerance after the use is phased out.
Available data support lowering tolerance.
EPA expects to revoke tolerance after the
use is phased out; however, tolerance should
be lowered in the interim.
EPA expects to revoke tolerance after the
use is phased out.
Tolerances Listed Under 40 CFR §180.183(a)(2)
Livestock Feed Items
Sugar beet pulp
Pineapple bran
Aspirated grain
factions
Cotton, gin
>yproducts
5
5
'
.
Revoke
Revoke
0.3
TBD4
No registered use on sugar beets; therefore,
tolerance should be revoked.
No registered use on pineapple; therefore,
tolerance should be revoked.
Based on wheat tolerance and concentration
factor from processing study. EPA expects
to establish a temporary tolerance, which
will be revoked following the phase out of
the use on wheat and barley, pending the
outcome of the OP cumulative assessment.
Animal feed item; tolerance to be
determined pending completion of field trial
study and outcome of OP cumulative
assessment.
Tolerances Listed Under 40 CFR § 1 80. 1 83(c)
Regional Registrations
65

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Commodity
Asparagus
Current
Tolerance (ppm)
0.10
Reassessed1
Tolerance (ppm)
0.10
Comment/
[Correct Commodity Definition]

1  "Reassessed" does not imply that the tolerances have been reassessed as required by FQPA; tolerances may only
be reassessed once the cumulative risk assessment of all OP pesticides is considered.
2  K+ CWHR, kernel plus cob with husks removed.
3 TBD, to be determined pending completion of outstanding field trial data (OPPTS GDLN 860.1500) and pending
the outcome of the cumulative assessment. Available data support a separate, higher tolerance for leaf lettuce.
4  TBD, to be determined. Field trial data (OPPTS GDLN 860.1500) are now required for cotton gin byproducts.

       Raw Agricultural Commodities, 40 CFR § 180.183(a)(l)

       The following tolerances should be revoked because there is no longer a registered use on
these commodities:
       Sugar Beets, all tolerances
       Hops
       Spinach
Pineapples, all tolerances
Rice, all tolerances
Sugarcane
       The following tolerances should be revoked because the technical registrant has
requested, and EPA has approved, voluntary cancellation of disulfoton use on these
commodities:
       Beans, dry
       Beans, vines
       Corn, all tolerances
       Oats, all tolerances
       Peas, all tolerances
Pecans
Sorghum, all tolerances
Soybeans, all tolerances
Tomatoes
       The following tolerances will be lowered based on available residue data:
       Barley, grain
       Coffee beans
       Peanuts
Potatoes
Wheat, grain
       In addition, the Agency expects to propose revocation of tolerances on barley, potatoes,
 and wheat because these uses are being phased out.  The revocation will allow sufficient time for
 legally treated commodities to clear the channels of trade.

       Livestock Feed Items, 40 CFR §180.183 (a) (2)

       A tolerance must be established for residues of aspirated grain fractions.  The
 concentration factors for wheat aspirated grain fractions was 1.35x. The reassessed tolerance for
 wheat grain is 0.2 ppm.  Multiplying concentration factors by the reassessed tolerances gives 0.3
 ppm for aspirated grain fractions of wheat.
                                             66

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       As explained in the Agency's definition of livestock feed commodities (OPPTS
 Guideline 860.1000, Table 1), tolerances are required for cotton gin byproducts. The appropriate
 tolerance levels for these commodities will be determined when adequate field trial data (OPPTS
 GDLN 860.1500) have been submitted and evaluated.

       A tolerance of 0.05 ppm, the level of quantification, would address potential residues on
 meat, fat, and meat byproducts of cattle, hogs, horses, sheep, and goats. A tolerance of 0.01
 ppm, the level of quantification, should be established for milk.

       Residue Analytical Methods

       Adequate methods are available for data collection and tolerance enforcement for plant
 and livestock commodities. The Pesticide Analytical Manual (PAM) Vol. II lists the
 enforcement methods for demeton, paper chromatography and colorimetric methods, as Method
 I. A gas chromatography (GC) method (Method II) with potassium chloride thermionic
 detection is listed for the determination of disulfoton, its oxygen analogue, and their sulfoxides
 and sulfones in/on  plant commodities.  The GC enforcement Method in PAM calculates residues
 in terms of disulfoton, whereas the tolerance expression states that residues are calculated as
 demeton. The majority of data used for tolerance reassessment were collected using the
 enforcement GC method (or modification thereof). Therefore, the tolerance expression will be
 revised to state that residues are to be calculated as disulfoton.  This revision will also make the
 tolerance expression compatible with the Codex expression.

       Multiresidue methods are also available for disulfoton. PAM Volume I, Appendix I
 indicates that disulfoton, its sulfoxide and sulfone, demeton-S (disulfoton oxygen analogue), and
 its sulfoxide and sulfone are completely recovered (>80%) using Multiresidue Method Section
 302. Disulfoton is partially recovered (50-74%) and metabolites disulfoton sulfone and
 demeton-S are not recovered using Multiresidue Method §303.  Disulfoton is not recovered
 using §304.

                    c.     Endocrine Disrupter Effects

       EPA is required under the FFDCA, as amended by FQPA, to develop a screening
 program to determine whether certain substances (including all pesticide active and other
 ingredients)  "may have  an effect in humans that is similar to an effect produced by a naturally
 occurring estrogen, or other such endocrine effects as the Administrator may designate."
 Following the recommendations of its Endocrine Disrupter Screening and Testing Advisory
 Committee (EDSTAC), EPA determined that there were scientific bases for including, as part of
 the program, the androgen and thyroid hormone systems, in addition to the estrogen hormone
 system. EPA also adopted EDSTAC's recommendation that the Program include evaluations of
potential  effects in wildlife.  For pesticide chemicals, EPA will use FIFPxA and, to the extent that
 effects in wildlife may help determine whether a substance may have an effect in humans,
FFDCA authority to require the wildlife evaluations. As the science develops and resources
allow, screening of additional hormone systems may be added to the Endocrine Disruptor
                                           67

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Screening Program (EDSP).

       When the appropriate screening and/or testing protocols being considered under the
Agency's EDSP have been developed, disulfoton may be subjected to additional screening
and/or testing to better characterize effects related to endocrine disruption.   ,

       D.     Regulatory Rationale

       EPA has determined that label amendments are necessary in order for disulfoton products
to be eligible for reregistration.  Provided the following risk mitigation measures are
incorporated in their entirety into labels for disulfoton-containing products, the Agency finds that
certain currently registered uses of disulfoton are eligible for reregistration, pending
consideration of cumulative risks of OP pesticides.  The regulatory rationale for each of the
mitigation measures is discussed below.  Where labeling revisions are warranted, specific
language is set forth in the summary table of Section V.

              1.     Human Health Risk Mitigation

                     a.     Dietary Mitigation

       Dietary risk from food sources alone are not of concern. Screening level modeling
estimates indicate that aggregate disulfoton exposure from food and drinking water may fill the
risk cup; however, the Agency has determined that drinking water exposures are likely lower
than predicted. Therefore, the Agency has made an interim determination that no additional
mitigation are necessary at this time.  EPA will require additional data to refine the drinking
water modeling values an'd confirm this interim conclusion.

       Acute (Food)

       The acute dietary (food) risk estimate is less than 100% of the aPAD for the general  ;
population and all  population subgroups. Children (1-6 years), the most highly exposed
population group, are exposed to disulfoton at a level of 9.6% of the aPAD (0.0025 mg/kg/day)
at the 99.9th exposure percentile. The acute dietary  (food) risk estimate is not of concern;
therefore, no additional mitigation measures are necessary to reduce these risks.

       Chronic (Food)

       The chronic dietary (food) risk estimate is less than 100% of the cPAD for the general
population and all  population subgroups. Children  (1-6 years), the most highly exposed
population group, are exposed to disulfoton at a level of 3.5% of the cPAD (0.00013 mg/kg/day).
The chronic dietary (food) risk estimate  is not of concern; therefore, no additional mitigation
measures are necessary to reduce these risks.                                            ••
                                            68

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       Drinking Water - Surface

       Surface water drinking water estimated concentrations (DWECs) were derived from the
 Tier IIPRZM-EXAMS model with the Standard Index Reservoir and percent crop area (PCA),
 which is a screening-level model designed to provide high-end estimates of potential pesticide
 exposure. Model predictions provide a screen to eliminate those chemicals that are not likely to
 cause concerns in drinking water. Exceedances in drinking water risk assessments using the
 screening model estimates do not necessarily mean a risk of concern actually exists, but may
 indicate the need for better data (e.g., monitoring studies specific to use patterns and drinking
 water sources) on which to confirm decisions.

       Based on model predictions of currently registered uses, the DWECs for disulfoton
 (parent only) in surface water range from 2.8 to 15.5 ppb for acute exposure, and from 0.2 to 1.6
 ppb for chronic exposure.  The DWECs for total disulfoton (parent + degradates) range from 8.0
 ppb to 39.0 ppb for acute exposure, and from 2.0 to 16.7 ppb for chronic exposure and are
 summarized in Table 5.

       As part of the Agency's measures to mitigate occupational risks associated with the use
 of disulfoton (discussed later in this section), certain use sites are to be phased out or
 discontinued.  Among the uses to be discontinued are barley, potatoes, and wheat.  However,
 disulfoton use on these crops and cotton were selected to assess overall drinking water exposures
 from surface water sources.  Excluding the crop scenarios  for barley, potatoes, and wheat would
 result in cotton use as being the only remaining drinking water crop scenario from which to
 assess drinking water risks. However, disulfoton is used on many other crops, such as
 asparagus, beans, broccoli, brussels sprouts, cabbage, cauliflower, chilli peppers, lentils, lettuce,
 peanuts, and peas.  T;hese use sites were not specifically modeled, because the  barley, cotton,
 potatoes, and wheat crop scenarios were selected to be representative of all sites vulnerable to
 runoff. Thus, to represent the use of disulfoton on all the use sites subject to reregistration, it is
 appropriate to use the DWEC model estimates from the original barley, cotton, potatoes, and
 wheat crops scenarios to assess drinking water risks from surface water sources.

       For disulfoton, the fate of the parent compound and its degradates once in surface water
 and sediments, and the likely concentrations therein, cannot be modeled with a high degree of
 certainty, since aerobic and anaerobic aquatic degradation  data are not available. Because there
 are no studies for individual degradates, a 259 day half-life was used for a model input, which is
 the upper 90% confidence bound on the mean of total residue half-lives in aerobic soil
 metabolism studies. The assessment.could be refined if studies for the individual degradates
 were conducted and model inputs could be derived from these studies. In addition, the aerobic
 soil metabolism half-life is used to estimate the aerobic aquatic half-life when aerobic aquatic
 data are not available, and has also contributed to the uncertainty of the  water assessment.

       In addition, the water model scenarios on disulfoton use on barley and potatoes, which
result in the highest DWECs, include the default PCA value of 87%. This factor translates to
 87% of the modeled drainage basin is planted with crops which are treated with disulfoton. This
                                           69

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default value may be an overestimate, since some of the disulfoton use areas are highly mixed
agricultural regions where other crops that are not treated with disulfoton are also grown or areas
where no crops are grown and disulfoton is not applied.

       Because modeling without complete fate data was employed to develop DWEC values to
assess drinking water risks for disulfoton, the Agency has some level of uncertainty of whether
actual concentrations of disulfoton in surface water sources of drinking water would be as high
as the model predictions. Therefore, to confirm these estimates, aerobic and anaerobic aquatic
metabolism, and mobility, leaching, absorption and desorption studies (OPPTS Guidelines
835.4300, 835.4400, and 835.1240) on both the parent and degradates are required.

       For many chemicals where there are uncertainties in the modeling estimates, the Agency
also relies on actual  monitoring data to confirm these estimates. Thus, for disulfoton, the
Agency is also requiring confirmatory surface water monitoring data to evaluate actual acute and
chronic concentrations of disulfoton in the drinking water sources. This monitoring data is to be
generated from a multi-year sampling program involving community water systems from surface
water sources in multiple locations in different regions of the country to represent different use
sites, crops,  soil types, and rainfall regimes.  Water samples are to be analyzed to determine the
concentrations of parent disulfoton and each of the  environmental degradates of toxicological
concern. Also, prior to initiating this sampling program, the registrant is required to submit a
study protocol to the Agency to ensure that the sampling locations and procedures are adequate
to address the drinking water risk concerns.

       Drinking Water - Ground

       The DWEC to assess drinking water risks from disulfoton concentrations in ground water
sources is 1.2 ppb. A Tier I screening-level model  (SCI-GROW)  was employed to estimate the
maximum ground water concentrations from the application of a pesticide to crops. The model
is based on the fate properties of the pesticide and the annual application rate. For disulfoton,
fate data were not available for the degradates of concern; thus, estimates of fate properties were
factored into the model estimates, which comprise a significant contribution to the predicted total
concentration of disulfoton. Furthermore, the model assumes the  pesticide is applied at its
maximum rate in areas where the ground water is particularly vulnerable to contamination. In
most cases, a considerable portion of any use area will have ground water that is less vulnerable
to the contamination than the use areas used to derive the model estimates. As such, the DWECs
from this model should be considered a high-end to bounding estimate that is generally more
appropriate for acute rather than chronic exposure.

       In addition, the available monitoring data do not indicate that there is a concern of
disulfoton concentrations in drinking water from ground water sources.  For these reasons, the
Agency believes that actual concentrations of disulfoton in ground water sources of drinking
water are not of risk concern, and that no further mitigation nor monitoring is necessary.
                                           70

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                     b.     Homeowner Risk Mitigation

       Handler Risk

       Disulfoton is currently registered for residential use on small flower gardens, ornamental
 flowers and shrubs, including rose bushes and small trees, and outdoor potted plants. Most
 application methods for residential uses are not of risk concern to the Agency with MOEs > 100;
 however, some uses result in MOEs < 100 and are of risk concern. As indicated in Table 8,
 MOEs for residential uses of disulfoton range from 1.1 to 1900.  Residential risks are not of risk
 concern fMOEs > 100) for the following use scenarios and application rates:

 •      Loading/applying graniilars using a push-type spreader:
       -use on flower gardens at an application rate of 0.3 Ib ai/1000 ft2
       -use on ornamental shrubs and small trees at an application rate of 0.01 Ib ai/4 ft shrub
       -use on rose bushes at an application rate of 0.00126 Ib ai/bush
                                                            ^
       Loading/applying granulars using a spoon, measuring scoop, shaker can or by hand:
       -use on potted plants at an application rate of 0.00034 Ib ai/6 inch pot
       -use on rose bushes at an application rate of 0.00126 Ib ai/bush

 •      Loading/applying granulars using a measuring cup/lid:
       -use on flowerbeds at an application rate of 0.21 Ib ai/1000 ft2
       -use on shrubs at an application rate of 0.01  Ib ai/4 ft shrub
       -use on rose bushes at an application rate of 0.0013 Ib ai/bush

 Residential risks are of risk concern CMOEs < 100) for the following use scenarios and
 application rates:

 •      Loading/applying granulars using a belly grinder:
       -use on flower gardens at an application rate of 0.3 Ib ai/1000 ft2

       Loading/applying granulars using a spoon, measuring scoop, shaker can or by hand:
       -use on flower gardens at an application rate of 0.3 Ib ai/1000 ft2
       -use on ornamental shrubs and small trees at an application rate of 0.01 Ib ai/4 ft shrub

The following measures are necessary to mitigate residential risks that are of concern:

•      Prohibit application of disulfoton with a belly grinder.

       Prohibit application to flower gardens and ornamental shrubs with a spoon, measuring
       scoop, shaker can,  or by hand, unless the  packaging and method of application of the
     ,  end-use product conforms with the performance of a measuring cup/lid packaging
       currently manufactured for the Bayer Advanced Garden 2-in-l Systemic Rose and
       Flower Care® Disulfoton 1% granular product.
                                          71

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       If the end-use registrant elects to change container packaging to conform with the subject
       Bayer product, the new packaging must be child resistant with a self-contained
       measuring device, which serves as the container lid and clearly measures the quantity to
       be applied. Although the Bayer Advanced Garden 2-in-l Systemic Rose and Flower
       Care® Disulfoton 1% granular product is the only such packaging of this type currently
       available at the time of this IRED, other similar packaging which meets or exceeds the
       safety specifications given above may also be used.               ;

•      Limit the maximum label rates for disulfoton to 0.3 Ib ai/1000 ft2 for use on flowerbeds;
       0.01 Ib ai/4 ft bush for use on shrubs; and 0.0013 Ib ai/bush for use on rose bushes.
       Although the residential risk assessment for hand application with a self-contained
       measuring cup/lid was based on a rate of 0.21 Ib ai/1000 ft2 on flowerbeds (Table 8), the
       MOEs calculated for the rate of 0.3 Ib ai/1000 ft2 for use on flowerbeds would also be
       greater than 100 and not of risk concern. To be consistent with the maximum application
       rate to flowerbeds with a push type spreader, EPA is allowing the higher maximum
    .   application rate 0.3 Ib ai/1000 ft2 for use on flowerbeds for disulfoton packaged for hand
       application with a self-contained measuring cup/lid.

       As previously stated, all disulfoton products intended for hand application must be
       packaged with a self-contained measuring cup/lid that clearly measures the appropriate
       amount to be applied.  These packaging must also meet EPA criteria for child-resistant
       packaging.

       Disulfoton products intended for application with a push-type spreader must limit the
       maximum application rates to 0.3 Ib ai/1000 ft2 for use on flowerbeds; 0.01  Ib ai/4 ft bush
       for use on shrubs; and 0.0013 Ib ai/bush for use on rose bushes, as specified above. Also,
       these products must be labeled "Do not apply by hand." and "Not for commercial use."

•      All homeowner products must be soil incorporated or watered in.

       Delete the following uses from all product labels to comply with the technical label: all
       indoor uses, use in greenhouses, and use on home vegetable gardens, including use on
       spinach and tomatoes.

       Only homeowner products containing 2% active ingredient or less  are eligible  for
reregistration. (All products containing >2% active ingredient are classified as restricted use,
based on the acute oral and dermal toxicity of disulfoton).

       Residential risk from use of fertilizer spikes impregnated with disulfoton can not be
determined at this time, because the Agency has no exposure monitoring data for this use
scenario. Similarly, EPA can not determine the reregistration eligibility for this use without
exposure monitoring data (i.e, OPPTS Guidelines 875.1100, 875.1600, and 875.1700). La some
cases, the Agency would require these data as a condition of continued registration. However,
                                           72

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 on March 28, 2002, the end-use registrant requested voluntary cancellation of all product
 registrations for fertilizer spikes impregnated with disulfoton (EPA Reg Nos 46260-2,46260-12,
 46260-35, and 46260-36); therefore, the Agency does not intend to include these data
 requirements in the DCI. Consistent with the existing stocks provision of this IRED, the end-use
 registrant will be allowed 26 months from the date of issuance of this document to distribute and
 sell products and 50 months for persons other than the registrant to distribute or sell products

       Post-Application Risk

       As mentioned previously in this document, the upper-bound .residential post-application
 assessment of incidental soil ingestion (oral exposure) to toddlers results in MOEs > 100, which
 are not of risk concern to the Agency.  Therefore, the Agency does not have a concern for post-
 application risk to toddlers from any activities, and no additional mitigation is necessary.

                     c.      Aggregate Risk Mitigation

       The Agency's aggregate risk assessment for disulfoton is based on exposure estimates for
 food and residential uses, and uses, a screening-level assessment of modeled estimates for
 drinking water contamination. Dietary (food) risk estimates are based on a refined assessment
 that incorporates percent crop treated data, monitoring data, and processing data.

       Acute Exposure

       The acute aggregate risk assessment for disulfoton combines exposure from food and
 drinking water sources only. Acute dietary (food) risk estimates are below 100% of the aPAD
 for the US population and all population subgroups.  Children 1-6 years old is the most highly
 exposed population subgroup and result in an acute drinking water level of comparison
 (DWLOC) of 23 ppb. Based on screening-level model predictions of the remaining supported
 uses, the acute (peak) drinking water estimated concentration (DWECs) in surface water is 15.5
 ppb for parent disulfoton and 39.0 ppb for total disulfoton (parent + degradates). The DWEC of
 parent disulfoton is less than the DWLOC and not of concern; however, the DWEC of total
 disulfoton (parent + degradates) is greater than the DWLOC and is of potential risk concern to
 the Agency as modeled. Also, the screening-level model predictions of acute DWECs in ground
water is 1.2 ppb for total disulfoton, which is less  than the DWLOC and not of risk concern to
the Agency.

       As stated previously, exceedances of the DWLOC by screening-level model estimates do
not necessarily indicate a risk of concern, but generally indicate the need for better data, due to
the uncertainties and limitations of the model predictions. The Agency believes that actual acute
concentration of disulfoton in surface water is likely less than the DWLOC and is not of concern.
To demonstrate this, confirmatory surface water monitoring data is to be generated to address
this risk concern.     .
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       Chronic Exposure

       The chronic aggregate risk assessment for disulfoton combines exposure from food and
drinking water sources only.  Chronic dietary (food) risk estimates are well below 100% of the
cPAD for the US population and all population subgroups. Children 1-6 years old is the most
highly exposed population subgroup with a chronic DWLOC of 1.3 ppb. Based on screening-
level model predictions of the remaining supported uses, the average (chronic) DWECs in
surface water is 1.6 ppb for parent disulfoton and 16.7 ppb for total disulfoton (parent +
degradates). The DWEC of parent disulfoton is of the same magnitude as the chronic DWLOC
and is not of concern. Although the DWEC for total disulfoton is greater than the DWLOC for
children 1-6 and is of potential risk concern, the uncertainties and limitations of the model
predictions lessen this concern. The Agency also believes that actual chronic concentrations of
disulfoton in surface water are less than the DWLOC and are not of concern. To demonstrate
this, confirmatory laboratory fate and surface water monitoring data are to be generated to
address the risk concern.

       The screening-level model predicts a chronic DWECs in ground water of 1.2 ppb, a value
lower than the corresponding DWLOCs.  Therefore, the Agency believes that concentrations of
disulfoton in ground water sources of drinking water are not of risk concern, and that no further
mitigation or monitoring is necessary.

       Short-Term Exposure

       The short-term aggregate risk assessment for disulfoton combines exposure from food
uses, residential uses, and drinking water sources. Residential use is assessed for dermal
exposure to adult handlers and oral exposure to children through incidental soil ingestion.  .
Inhalation exposure is not part of the short-term aggregate assessment as data indicate negligible
exposure. Short-term DWLOC estimates are calculated for disulfoton based on chronic dietary
(food) exposure and dermal exposure values from residential exposure scenarios that have MOEs
> 100. Residential exposure  scenarios with MOEs < 100 were  not included in the short-term
aggregate assessment (see Table 8).

       The short-term DWLOC is 14 ppb for children 1-6 years old, the most highly exposed
population.  As indicated above, the average (chronic) DWECs in surface water is 1.6 ppb for
parent disulfoton and 16.7 ppb for total disulfoton (parent + degradates).  The DWEC of parent
disulfoton is less than the short-term DWLOC and not of concern. Although the DWEC for total
disulfoton is slightly greater than the DWLOC, th Agency believes this exceedance does not
necessarily indicate a risk of concern due to the uncertainties associated with model estimates.
Confirmatory laboratory fate and surface water monitoring data are to be generated to address
the potential risk concern.

                    d.     Occupational Risk Mitigation

       As described in PR Notice 2000-9, Worker Risk Mitigation for OP Pesticides, it is the
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 Agency's policy to mitigate occupational risks to the greatest extent necessary and feasible with
 personal protective equipment and engineering controls. In managing risk, EPA considers a
 wide range of factors are considered in making risk management decisions for worker risks. EPA
 must take into account the economic, societal, and environmental costs and benefits of the
 pesticide's use. In addition to the calculated MOEs, incident data, the nature and severity of
 adverse effects, uncertainties in the risk assessment, availability and relative risk of alternatives,
 importance of the chemical in integrated pest management (IPM) programs, and other similar
 factors.

       Worker Handler Risks

       As summarized in Table 10, occupational risks are of concern (i.e., MOEs < 100) for all
 scenarios, even when maximum PPE (i.e, double layer clothing, gloves, and a respirator) are
 utilized.  These handler risks are also of concern for many scenarios with engineering controls,
 even at a level that provides protection from inhalation exposure (closed mixing/loading,
 enclosed cabs with ah- filtration). Engineering controls with inhalation protection are considered
 to be the maximum feasible mitigation.  For workers wearing the maximum PPE described
 above, MOEs range from 1.5 (barley) to 61 for mixer/loaders and from <1 (ornamentals grown
 for field or nursery stock) to 69 for applicators. For workers using the engineering controls
 described above, MOEs range from 3.1 to 800 for mixer/loaders and from 1.8 to 160 for
 applicators.  To remain eligible for reregistration, the following mitigation measures must be
 implemented for all occupational handler scenarios.

 •      Closed mixing/loading systems for all liquid formulations (see below);

       Closed transfer/loading systems for all granular formulations by June 2004;

       Enclosed cabs plus a dust-mist respirator for all ground equipment applicators (i.e.,
       groundboom and tractor drawn spreader). The respirator requirement may be relaxed
       when using engineering controls that provide equivalent inhalation protection (such as air
       filtration), under the provisions of the Worker Protection Standard (WPS).

•      Enclosed cockpits for aerial applicators;

       Mechanical flaggers for aerial application; or the use of global positioning system (GPS)
       equipment that negates the need for flaggers;,

•      When engineering controls are not feasible for applicators, handlers must wear maximum
       PPE (i.e., double layer clothing, chemical-resistant gloves and footwear, and a dust-mist
       respirator); and                                                                  ,

       Application by open, handheld equipment, including belly grinders and bucket and spoon
       will be prohibited after June 2004. Where this is currently the application method of
       choice, growers will be allowed until June 2004 to transition to another method.
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       The closed mixing/loading system used for liquid disulfoton should contain a dry
disconnect or dry coupler that allows no more than 2 mL drippage, such as the Secure-Link G®
or other comparable system.  Closed mixing/loading systems for all liquid formulations of
disulfoton end-use products are currently in use and should be fully implemented by December
31,2002.
                                                                           V
       Post-Application Risk

       Post-application (re-entry) risks are of concern for workers performing tasks in areas that
have received foliar applications of disulfoton.  In lieu of satisfactory dislodgeable foliar residue
(DFR) data, the Agency relied on assumptions for its re-entry assessment. Restricted-entry
intervals (REIs) for these types of applications of disulfoton are stipulated in the crop specific
regulatory rationale section below. The Agency acknowledges thatjidditional DFR data (OPPTS
Guideline 875.2100) could refine the post-application risk assessment and likely reduce the REI
for certain crops. If the registrant wishes to generate such data to refine this assessment, the
study needs to include residue data on both the parent and degradates.

       For soil directed applications of the liquid and granular formulations, most of which are
either in-furrow, shank injected, or other types of soil incorporation, the Worker Protection
Standard designates the REI to be 48 hours, or 72 hours in regions where the annual rainfall is
less than 25 inches. In addition, based on the use of the chemical and the timing of applications
to these crops, the Agency does not expect significant  soil contact from typical worker re-entry
activities. Therefore, the Agency has no risk concerns for the post-application exposures to
agricultural workers for these types of disulfoton applications, and no risk mitigation measures
beyond the 48 or 72 hour REI are necessary for applications made to the soil.

       Uncertainty in and Refinements to the  Occupational Risk Assessment

       There is some uncertainty associated with the toxicity of disulfoton. Numerous animal
studies in several species show cholinesterase inhibition. The NOAEL used to assess  short-term
dermal exposure to workers is 0.5 mg/kg/day from a special 3-day dermal toxicity study in rats
conducted on the 1% granular product.  The LOAEL from this study is 1 mg/kg/day based on
plasma and brain cholinesterase inhibition. The Agency believes that the NOAEL from this
study is sufficient to assess dermal exposure of 1 to 7 days,  which would cover most agricultural
workers.  However, the Agency is concerned that commercial handlers could be exposed for up
to 14 days.  To fully characterize the hazard associated with exposure ranging from 14 to 30
days, the Agency is requiring a confirmatory 21-day dermal study in the rat, the most  sensitive
species. In the interim, the Agency will base the short-term dermal risk assessment for
commercial applicators on the 3-day dermal study. The Agency acknowledges that the
occupational risk assessment based on the 3-day dermal toxicity study may underestimate risk to
some commercial applicators.

       There is also some uncertainty in the Agency's assessment of exposure to agricultural
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 workers. EPA used exposure monitoring data from PHED, which either lacks or contains
 limited exposure monitoring data for some application methods, including shank injection, in-
 furrow, and with a motorcycle mounted with a granular spreader. In these specific examples, the
 closest available exposure monitoring data scenario from PHED was used to assess potential
 exposure.  The Agency made the following extrapolations based on PHED data:

 •     Data for mixers/loaders and applicators using a groundboom to apply liquid formulations
       were used to estimate exposure from at-plant, in-furrow application of liquid products.

 •     Data for loaders and applicators using a tractor drawn spreader to apply granular
       formulations were used to estimate  exposure from in-furrow, at-plant application and
       exposure from broadcast of granulars using a motorcycle.

       The Agency believes that in-furrow or  shank injecting methods of applications result in
 less exposure to applicators than does the tractor drawn spreader or groundboom methods, from
 which the estimated risks were derived. Although the Agency does not have data at this time to
 corroborate this understanding, it is reasonable to expect the risk associated with applying
 disulfoton with soil incorporated methods are lower than currently estimated. Because of the
 uncertainties associated with the use of these surrogate scenarios, the Agency is requiring
 confirmatory exposure monitoring data (passive dosimetry) to better characterize exposure and
 risk for these scenarios. However, because of the uncertainties associated with the dermal
 endpoint, the registrant has the option to generate, and the Agency will accept biomonitoring
 data in lieu of the passive dosimetry to characterize exposure to applicators.

       Last, the Agency typically uses default assumptions with regard to acreage treated per
 day for field crops depending upon the application method. However, crop-specific information
 shows that many minor crops grown in the Salinas Valley of California are planted in blocks,
 and that in many cases the actual acreage treated per day is lower than the Agency default
 assumptions. Because California's Department of Pesticide Regulation has stringent pesticide
 use reporting requirements, EPA verified acreage treated with disulfoton in that state, and
 concluded that for some crops that are grown in California, the actual acreage treated per day is
 lower than the assumptions used by the Agency to assess worker risks. Information on the
 acreage treated for specific crops grown in California, and its impact on corresponding worker
 MOEs are summarized with crop-specific mitigation in Section IV.D.3, Crop Specific Mitigation
 of this document.

             2.     Environmental Risk Mitigation

       The Agency's ecological risk assessment for both the liquid and granular formulations
shows RQ values which exceed the various  levels of concern (LOCs) for acute risks to terrestrial
birds and mammals and freshwater and estuarine invertebrates and chronic risks to birds and
mammals, freshwater invertebrates, as well  as marine and estuarine fish and invertebrates.  The
Agency also has risk concerns to endangered species, and potential concern to nontarget plants.
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      Birds and Mammals

      The Agency has some acute risk concerns for birds and mammals potentially exposed to
the liquid formulation. Acute RQs for birds range from 0.01 to 2.2, with the highest RQ
associated with use on potatoes.  EPA also has a risk concern for endangered avian species.
Acute RQs for mammals range from <0.1 to 360, again with the highest RQ associated with
potatoes. Note also that there is some uncertainty in the mammalian risk estimates,  because they
are based on rat toxicity studies, which were not designed to assess risk to wild mammals. In
lieu of wild mammal acute toxicity data, EPA extrapolated an LC50 value based on an LD50 from
an acute oral rat study to calculate acute RQs for mammals, which may account for  the
comparatively high RQs for mammals. In addition, EPA has some chronic risk concerns for
birds and mammals potentially exposed to the liquid formulation.  Chronic risk estimates for the
liquid formulation range from 0.02 to 3.4 for birds and from 0.9 to 158 for mammals.  The
highest RQ is for use on potatoes in the Pacific Northwest.  The Agency's phase out of
disulfoton use on potatoes will address the highest avian and mammalian acute and  chronic risks.

       The Agency also has acute risk concerns for the granular formulation, with potential risk
concerns at the lowest application rate of 1 Ib ai/A.  Acute avian RQs range from 0.1 to 75,200
and mammalian RQs range from 0.3  to 257,300. The highest RQs for both birds.and mammals
are associated with the Christmas tree use at the current Section 3 registration label  rate of 78 Ib
ai/A. To mitigate this risk, the maximum application rate for disulfoton on Christmas trees is to
be reduced to 4.5 Ibs ai/A, the use is to be limited to fir species only, and disulfoton must be
either soil incorporated, watered in, or applied to areas with permanent groundcover. At the
lower application rate of 4.5 Ibs ai/A for Christmas trees, peak RQs are significantly reduced to
4,350 for birds and 14,900 for mammals. Although the residual risks for the Christmas tree use
are still high, Christmas tree growers hi the region have submitted numerous testimonials
emphasizing the ever increasing numbers and diversity of wildlife, including game  animals.
Although it is not clear whether there are population effects, the risk assessments suggests that
there is acute risk to nontarget birds and mammals exposed to disulfoton. Excluding Christmas
tree  use, RQs for birds range from 0.1 to 346, and RQs for mammals range from 0.3 to 1184,
with the highest RQs associated with use of disulfoton by nurseries on ornamental flowers.

       Because of the toxicity of disulfoton, to help protect terrestrial birds and mammals, it is
very important to minimize their potential exposure to disulfoton products that have been
applied.  Many of the mitigation measures previously described in this document to mitigate
occupational and other risks of concern will also serve to minimize risk to birds and mammals,
such as deleting certain uses (i.e., potatoes, barley, wheat, ornamentals), injecting or
incorporating the chemical into the soil during application,  reducing maximum application rates,
and  limiting the number of applications on asparagus, coffee, peanuts (North Carolina only), and
potatoes.

       Aquatic Organisms

       Acute risks are of concern for some aquatic organisms. Acute RQs range from <0.01 to
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 0.33 for freshwater fish, and from <0.01 to 0.02 for estuarine fish, and are not of concern.
 However, acute RQs  range from O.01 to 2.1 for freshwater invertebrates, and from <0.01 to
 0.55 for estuarine invertebrates. Some of the acute values for invertebrates are of concern.

        Chronic risks are of concern for freshwater invertebrates, but not for freshwater fish. The
 Agency has a greater chronic risk concern for freshwater invertebrates than for estuarine
 invertebrates. Chronic RQs range from <0.01 to 149 for freshwater invertebrates, and from
 <0.01 to 2.3 for estuarine invertebrates.  For freshwater fish, chronic RQs range from <0.01 to
 0.8, and for estuarine fish, chronic RQs range from <0.01 to 3.0.

        The highest RQs of concern to fish and invertebrates are associated with multiple aerial
 applications to potatoes, barley, and asparagus. The phase out of disulfoton use on potatoes and
 barley will mitigate some of these risks, and the RQs associated with use on asparagus may be
 an overestimate.  Disulfoton use on asparagus is predominately in Washington and California,
 where there is little to no rainfall during the application period to cause runoff and potentially
 exposure aquatic  organisms.

        Many of the measures previously described in this document to mitigate occupational and
 terrestrial risks will also serve to mitigate, aquatic risks of concern. For instance, deleting certain
 uses, injecting or incorporating the chemical into the soil, reducing maximum application rates,
 and limiting the number of applications will reduce potential runoff of disulfoton to nearby water
 bodies.  To further.mitigate aquatic risks, a 25 foot vegetative buffer between treated fields and
 all permanent water bodies will be necessary.

       Plants

       Because test data was not available to conduct a risk assessment for nontarget plants, and
 because of a phytotoxicity statement on the labels, the Agency has a potential phytotoxicity risk
 concern. Given that disulfoton is applied to growing crops it is unlikely to result in significant
 nontarget risks to plants. Confirmatory data are needed to determine the extent of any risk that
 may exist.  Therefore, Tier I test data for terrestrial plants (OPPTS 850.4100 and 850.4150) are
 required.

      Insects

      The results of an acute contact study show that disulfoton is moderately toxic to bees and
 disulfoton sulfone and sulfoxide are very highly toxic to bees on an acute contact basis.  A
toxicity  study of residue of the liquid EC (Di-Syston 8) on honey bees showed that disulfoton
residues on foliage are not toxic to bees.  The Agency believe that a precautionary label
statement will be sufficient to  address risk concerns.  Specific label language is given in Table
 16 of this document.
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       Endangered Species

       As mentioned in Section III.B.3 of this document, the Agency included disulfoton in two
formal consultations with the USFWS on endangered species. These consultations occurred in
1983 and 1989. As a result of these consultations, the USFWS issued jeopardy opinions
identifying several endangered species, as well as reasonable and prudent alternatives and
measures to address the risk concern. These opinions are reflected in the EPA's endangered
species protection program county level interim bulletins. The disulfoton registration and use
patterns have changed significantly since 1989, and many uses have been deleted, maximum
application rates have been lowered, and the number of applications have been reduced.
Therefore, the Agency conducted an additional endangered species assessment on the remaining
registered disulfoton uses that would result in potential exposure to endangered species. From
these remaining uses, potential impacts were identified for.two bird species: the Puerto Rico
Plain Pigeon and the Mountain Plover. The Agency does not believe that any measures are
necessary to protect the Mountain Plover at this time.  The Plover is found in western states
where barley is grown, and this bird feeds on barley when the barley is young and less than three
inches tall. Because disulfoton is used on barley late in the season, when the crop is quite tall,
the Mountain Plover is not expected to be impacted by disulfoton use. Further, the use of
disulfoton on barley is being phased out by June 2005. The Agency does not believe that any
measures are necessary to protect the Puerto Rico plain pigeon. Potential exposure of this
species was an issue associated with the use of disulfoton on coffee. However, technical
assistance from the Puerto Rico office of the Fish and Wildlife Service revealed that this species
does not utilize or otherwise occur in areas of Puerto Rico where coffee is produced.  Therefore,
because there will be no effect on this species, no mitigation measures are necessary.

              3.      Crop-Specific Decisions

       The technical registrant, Bayer Corporation, has made a number of voluntary changes to
their FIFRA Section 3 disulfoton labels to address risk concerns. These voluntary label changes
include reducing maximum application rates or number of applications for some crops  and
deleting numerous uses. However, these voluntary measures were  not sufficient to fully address
the Agency's risk concerns. Therefore, EPA has identified additional measures necessary to
mitigate risks on a crop-by-crop basis, after considering all potential risk mitigation options, the
availability of alternatives and their effectiveness, and the benefits  associated with each use (see
Section HI.C, Alternatives and Benefits). These measures included additional reductions in the
rate and frequency of applications, where these are feasible.  In the process ?of developing crop-
specific mitigation measures, EPA considered current agricultural practices and the actual use of
disulfoton in the field.  In some cases, the current agricultural practices are protective of human
health and the environment given the benefits of continued use. In such instances, pesticide
product labels must be modified to reflect the current practice.  In developing mitigation, EPA
also considered personal protective equipment and engineering controls for workers and
precautionary labeling.

       As previously mentioned in the section describing measures necessary to mitigate worker
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 risks, growers will need to utilize engineering controls, which include the use of enclosed cabs.
 Growers with enclosed cabs that do not provide inhalation protection will also need to wear a
 dust-mist respirator; however, growers who have enclosed cabs with air filtration will not need
 any further inhalation protection.  The Agency recognizes that there may be some growers of
 minor crops who may not own the necessary equipment and therefore may be economically
 impacted by adopting engineering controls. However, EPA believes that custom applicators who
 have equipment with the necessary engineering controls are available to growers who may not
 have the necessary equipment themselves.

        Risk estimates are provided in the following section for both groundboom and tractor
 drawn spreader applicators that are in an enclosed cab and wearing a dust-mist respirator.
 Typical disulfoton labels specify maximum PPE (i.e., double layer clothing, and with or without
 a respirator).  For groundboom applicators of the liquid formulation with maximum PPE and
 without a respirator, the corresponding MOEs increase by a factor of 3x for an applicator in an-
 enclosed cab and wearing a dust-mist respirator (80% protection factor); and for groundboom
 applicators with maximum PPE and with a respirator, the MOEs increase by a factor of 1.9x.
 Similarly, for tractor drawn spreader applicators of the granular formulation with maximum PPE
 and without a respirator, the corresponding MOEs increase by a factor of 3.6x for an applicator
 in an enclosed cab and wearing a dust-mist respirator; and for tractor drawn spreader applicators
 with maximum PPE and with a respirator, the MOEs increase by a factor of 1.4x. The tabulated
 MOEs for applicator scenarios utilizing an enclosed cab with a dust-mist respirator are not
 included in Table 10 of this document, but the basis of these calculations are available in Revised
 Occupational Exposure Assessment for the Reregistration Eligibility Decision Document for
 Disulfoton, June 15, 2001, which can be found on the internet or the public docket.

       Despite all of the mitigation measures previously described in this document, residual
 worker risks are still of concern for some crops and application methods. The Agency's decision
 considered the risks and benefits of continued disulfoton use as well as the availability of
 effective alternatives. EPA's risk-benefit findings, residual risks, and crop-specific decisions are
 summarized below.

       Asparagus

       The liquid formulation only is registered for use on asparagus through FIFRA Section
 24(c) Special Local Need (SLN) registrations in Arizona, California, North Carolina, Oregon,
 and Washington.  The granular formulation is not registered on asparagus. Most disulfoton use
 on asparagus is in California and Washington, which account for 96% of its use on this crop. In
 Washington, 50% of the asparagus crop is treated with disulfoton, and in California, 70% of the
 crop is treated. The liquid product is  mostly aerially applied, but is sometimes applied by
 groundboom to the field edges to control the target pest, the European asparagus aphid. The
 current labels allow for up to three applications of disulfoton.  The available alternatives to
disulfoton are chlorpyrifos and dimethoate, but are not sufficiently efficacious in controlling the
European asparagus aphid; therefore,  the Agency believes that the critical need for the use of this
chemical outweigh the risks.
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       Based on information from the USDA National Agricultural Statistics Service (NASS),
the overall average asparagus farm size in California is 219 acres. Also, for asparagus farms in
Washington, no farm is greater than 300 acres, and the average asparagus farm size is 62 acres.
Other sources indicate that the maximum area that can be aerially treated in a day is about 75-
150 acres in Washington, and about 150-200 acres in California. This information indicates an
approximate 2 to 4-fold reduction in the default 350 acres treated per day used to assess
occupational risks associated with aerial applications.

       Applications of liquid disulfoton to asparagus are for foliar treatment; therefore, the REI
for workers  to re-enter treated fields is 26 days.  However, because disulfoton is applied to
asparagus post-harvest, during the fern stage when growers do not need to re-enter treated fields,
this long REI is not expected to pose an undue hardship to growers. Also, the WPS allows REI
exemptions  to cover certain critical activities.
Scenario
Aerial
Groundboom
Worker MOE with Engineering Controls
Mixer/Loader
22
46
Applicator
34
(66)
REI
26 days •
The aerial scenario is based on 175 acres treated/day

       Asparagus Decision. Use of the liquid formulation only is eligible for reregistration,
and only in states where disulfoton is registered as a 24(c) SLN for asparagus.  The maximum
number of allowable applications for asparagus must be reduced from three times per year to two
times per year to help mitigate ecological risks.  Also, the REI is to be extended to 26 days.

       Barley and Wtieat

       Both liquid and granular formulations are registered for use on barley and wheat, but
late-season aerial application of the liquid appears to be the predominant use. Use of disulfoton
on these crops has been declining in recent years with <1% of either crop being treated
nationally. Disulfoton is used to control late-season infestations of Russian wheat aphid in
malting barley, which is used in beer production. Approximately 3% of all acres planted in
barley experience localized pockets of aphid infestation. The limited acreage of malting barley
crops that are affected by aphid damage are sometimes downgraded to lower value feed barley,
depending upon the plumpness of the kernel.

       The main alternative available to malting barley growers is lambda cyhalothrin
(Warrior®), which is currently only available as a FIFRA Section 18 registration in certain
states. Imidacloprid is also available to barley growers.  Barley growers have been increasingly
using lambda cyhalothrin to control aphids, which is contributing to the decline in disulfoton use.
Although lambda cyhalothrin is more expensive'than disulfoton, the cost differential does not
appear to be a disincentive for growers, because it is clearly the preferred choice for treating
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malting barley and is considered a safer alternative to disulfoton.  However, growers have
expressed some concern about the potential of aphids to develop resistance to the synthetic
pyrethroid, lambda cyhalothrin.  The Agency recognizes that resistence has been a problem with
certain synthetic pyrethroids, but is unable to use this information to predict likely grower
experience with lambda cyhalothrin in future years.  A FIFRA Section 3 registration for lambda
cyhalothrin on wheat, barley, and other cereal grains is pending and is expected to be granted in
2002.

       As with its use on barley, only a small percentage of wheat fields are treated with
disulfoton. When disulfoton is used on wheat, it is to control the Barley Yellow Dwarf Virus,
which is transmitted by aphids.  The highest reported use of disulfoton on wheat is in Kentucky,
where a late-season application of the liquid is made by custom applicators. In addition to the
pesticides that are available to barley growers, some of the key alternatives available to wheat
growers are chlorpyrifos, malathion, methomyl and pyrethrins.  The Agency considers the
benefits associated with the use of disulfoton on barley, including the availability and
effectiveness of alternatives, including lambda cyhalothrin, to be similar to its use on wheat.

       Foliar applications of liquid disulfoton resulted in post-application risk concerns for up to
16 days after application to barley, and  13 days after application to wheat.  Therefore, the REI
for workers to re-enter treated fields is 16 days for barley and 13 days for wheat for this type of
application. Because barley and wheat  are mechanically harvested, this longer REI is not
expected to pose an undue hardship to growers.  Also, the WPS allows REI exemptions to cover
critical activities,  such as irrigation, agricultural emergencies, or short-term activities.  MOEs
and REIs are summarized.below for barley and wheat use.
Scenario
Worker MOEs with Engineering Controls
Mixer/Loader
Applicator
REI
BARLEY
Aerial (liquid)
Aerial (granular)
Groundboom
Granular Tractor-Drawn Spreader
3.1
53
18
320
5.1
1.8
(27)
(37)
16 days for foliar
applications with
liquid formulation
48/72 hours for
granular
formulation
WHEAT
Aerial (liquid)
Aerial (granular)
Groundboom
Granular Tractor-Drawn Spreader
4.1
53
18
320
6.8
1.8
(27)
(37)
13 days for foliar
applications with
liquid formulation
48/72 hours for
granular
formulation
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( ) Indicates risk estimate for an applicator in an enclosed cab with a dust/mist respirator

       Barley and Wheat Decision: Use of both the liquid and granular formulation on barley
and wheat are to be phased out by June 2005 to allow time for growers to transition to
alternatives, including lambda cyhalothrin. In the interim, the REI for foliar application is to be
extended to 16 days for barley and 13 days for wheat. For disulfoton applications that are soil
directed, the REI remains at 48/72 hours. Also, the technical registrant had requested the liquid
(Di-Syston SEC) label for use on wheat be changed to reduce the number of foliar applications
from two to one, for a seasonal maximum rate of 0.75 Ib ai/A.

       Snap and Lima Beans

       Both the liquid and granular formulations are registered for use on beans, and growers
use both formulations.  Based on data from 1987 to 1998, approximately 12% of planted beans
are treated with disulfoton. Disulfoton is applied at-plant and soil incorporated (i.e., in-farrow
and injected as a side-dressing) to control thrips.  Most of disulfoton use on lima beans is in
Georgia, where 20-30% of the crop is treated. At present, foliar application of acephate is the
only alternative pesticide to control thrips on lima beans. Disulfoton use on snap beans to
control the potato leaf hopper is sporadic and appears to be declining. The target pest occurs
intermittently and does not require control every year.  Registered alternatives to disulfoton on
snap beans include other organophosphates (acephate and dimethoate) or carbamates (carbaryl
and methomyl).

       The occupational risk estimates for this use are summarized below.  As stated earlier, the
Agency has some uncertainty regarding risk  estimates for crops where disulfoton is either shank
injected or applied in-furrow, such as beans. The Agency believes that these soil incorporated
methods of application result in less exposure to the applicator than does the groundboom or
tractor spreader methods, from which the estimated risks are derived.
Scenario
Groundboom
Tractor-Drawn Spreader
Worker MOEs with Engineering Controls
Mixer/Loader
23
800
Applicator
(33)
(91)
REI
48/72 hours
( ) Indicates risk estimate for an applicator in an enclosed cab with a dust/mist respirator

       Bean Decision: Use of both the liquid and granular formulation on snap and lima, beans
are eligible for reregistration. The technical registrant has reduced the maximum rate for the
granular formulation from 2 Ibs ai/A to 1 Ib ai/A (which is reflected in the above table). Because
disulfoton applications are soil directed, the REI remains at 48/72 hours.

       Cabbage

       Both the liquid and granular formulations are registered for use on cabbage, and are used

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mostly as a rescue remedy for cabbage aphid and green peach aphid infestations. The liquid
formulation is shank injected and the granular formulation is applied as a soil incorporated band
or side-dressing.  Chemigation is an application method no longer being practiced by growers.
According to USDAISTASS data for the year 2000, approximately 3,400 Ib ai of disulfoton was
applied, with 3% of all cabbage grown nationally being treated with disulfoton. Most .disulfoton
use on cabbage is in California, where from 1997 to 1999, an average of 3100 Ibs ai of disulfoton
was applied to cabbage, primarily in Ventura County.  Both the liquid and granular formulations
of disulfoton are used in California. Imidacloprid is the main alternative, but it does not provide
the same long residual control as disulfoton.  Disulfoton provides the advantage of protecting
cabbage plants from aphid infestation for the entire season, and if it were not available, may
necessitate multiple applications imidacloprid.

       The occupational risk estimates for this use are summarized below.  As stated earlier, the
Agency has some uncertainty regarding risk estimates for crops where disulfoton is either shank
injected or applied in-furrow, such as cabbage. The Agency believes that these soil incorporated
methods of application result in less exposure to the applicator than does the groundboom or
tractor spreader methods, from which the estimated risks are derived.
Scenario
Groundboom
Tractor-Drawn Spreader
Chemigation
Worker MOEs with Engineering Controls
Mixer/Loader
23
530
Applicator
(33)
(62)
5.3
REI
48/72 hours
( ,) Indicates risk estimate for an applicator in an enclosed cab with a dust/mist respirator

       Cabbage Decision: Use of both the liquid and granular formulation on cabbage are
eligible for reregistration, provided the Chemigation application methods is deleted from labels.
Because disulfoton applications are soil directed, the REI remains at 48/72 hours.

       Cole Crops (Broccoli, Brussels Sprouts, Cauliflower)

        Both the liquid and granular formulations are registered for use on broccoli, Brussels
sprouts, and cauliflower.  The liquid is used exclusively in California's Salinas Valley, where it
is applied by shank injection once per season as a rescue remedy to control cabbage and green
peach aphids.  Within the Salinas Valley, Monterey County appears to be where the liquid
formulation is used predominantly. The importance of disulfoton use on cole crops in California
is demonstrated by the usage data from 1997 to 1999 for Monterey County, California which
indicate that as much as 60% of broccoli, 87% of Brussels sprouts, and 52% of cauliflower that
was grown was treated with disulfoton.  The granular formulation is mainly used on cole crops
grown outside  California.

       Registered alternatives to disulfoton on cole crops include imidacloprid and the OP
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pesticides oxydemeton-methyl, dimethoate, and chlorpyrifos.  Currently, imidacloprid is applied
at-plant, but it does not control the cabbage aphid throughout the entire growing season, due to
its limited period of residual effectiveness.  Also, imidacloprid is not effective as a foliar
application. Chlorpyrifos is toxic to beneficial insects and also causes phytotoxicity at the high
rates required to control the cabbage aphid.

       Commercial applicators in California, who treat many farms and therefore receive the
most exposure, generally treat no more than 40 acres per day. Private growers treat even less
acreage. While commercial applicators may treat more than one farm during severe aphid
outbreaks, they typically apply disulfoton no more than two or three times in one week.  To
assess risk based on typical current practices in California, the Agency adjusted worker MOEs in
the table below to reflect the assumption that no more than 40 acres are treated per day for cole
crops. Also, the Agency has some uncertainty regarding risk estimates for crops where
disulfoton is either shank injected or applied in-furrow, such as cole crops. The Agency believes
that these soil incorporated methods of application result in less exposure to the applicator than
does the groundboom or tractor spreader methods, from which the estimated risks are derived.
Scenario
Groundboom
Tractor-Drawn Spreader
Chemigation
Worker MOEs with Engineering Controls
Mixer/Loader
92
800
Applicator _
(132)
(91)
96
REI
48/72 hours
( ) Indicates risk estimate for an applicator in an enclosed cab with a dust/mist respirator
MOEs for both groundboom and chemigation use are adjusted to reflect 40 acres treated/day

       Cole Crop Decision: Based on the reduced acreage treated assumption for the
groundboom and chemigation scenarios, the corresponding MOEs for mixers/loaders and
applicators are near or above the target MOE of 100, and are therefore not of concern to the
Agency. Hence, use of both the liquid and granular formulation'on cole crops are eligible for
reregistration. However, because the liquid formulation is used exclusively in California, the
Section 3 label is to be modified to limit use to California only, which reflects current
agricultural practice.  Because disulfoton applications are soil directed, the REI remains at 48/72
hours. Also, to mitigate ecological risk, the technical registrant has reduced the number of soil
applications for broccoli and cauliflower from two to one, for a seasonal total of 1 Ib ai/A.  •

       Lettuce

       Only the liquid formulation of disulfoton is registered for use on lettuce. Disulfoton is
applied pre-plant or at-plant by banding. Nearly all (>95%) iceberg lettuce and leaf lettuce
grown in the United States is produced in California and Arizona. Based  on 1987 to 1998 usage
information, a weighted average of approximately 13,000 Ibs ai of disulfoton was applied to
lettuce nationally. However, most of disulfoton use on lettuce is in California, where frorja 1997
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 to 1999 an average of approximately 11,000 Ibs ai of disulfoton was applied to lettuce.  No use
 of disulfoton has been reported in other major lettuce producing states, including Florida and
 Arizona.

       Disulfoton use on lettuce in California is mostly limited to the Salinas Valley, which
 includes Monterey County. Approximately 59% of the total amount of disulfoton that is used on
 head lettuce is used in Monterey County, and 57% of the total amount of disulfoton that is used
 on leaf lettuce is also used in Monterey County. The surrounding counties that encompass
 Salinas Valley consume much of the remaining amount of disulfoton used on lettuce. Disulfoton
 is used in this area primarily to control the lettuce root aphid, which is harbored in Lombardy
 poplars, a popular ornamental.  Growers have indicated that root aphid infestation could result is
 as much as 20-30% of individual field loss. The main  pesticide alternative available is
 imidacloprid,  which has a short residual activity and therefore does not provide adequate control.
 As such, disulfoton is used as a rescue remedy, when other methods of pest control fail.

       As mentioned previously, private growers and commercial applicators in the Salinas
 Valley generally treat fewer acres per day than was assumed in the occupational risk assessment.
 To assess risk based on typical current practices in California, the Agency adjusted worker
 MOEs in the table below to reflect the assumption that no more than 40 acres are treated per day
 for lettuce.
Scenario
Groundboom
Chemigation
Worker MOEs with Engineering Controls
Mixer/Loader ,
46
Applicator
(66)
46
REI
48/72 hours
( ) Indicates risk estimate for an applicator in an enclosed cab with a dust/mist respirator
MOEs for both groundboom and chemigation use are adjusted to reflect 40 acres treated/day

       Lettuce Decision; Use of the liquid formulation on lettuce is eligible for reregistration.
However, because the liquid formulation is used exclusively in California, the Section 3 label is
to be modified to limit use to California only, which reflects current agricultural practice.
Because disulfoton applications are soil directed, the REI remains at 48/72 hours.

       Cotton

       Both the liquid and granular formulations are registered for use on cotton.
Approximately half of all disulfoton annually produced is used on cotton (420,000 Ibs ai), with
5-8% of the crop being treated.  Most use is in Louisiana, Missouri, Mississippi, and Texas, with
some use in Alabama, Arkansas, Georgia, Florida, Tennessee, the Carolinas, and Virginia.
Disulfoton is predominately used as a safener to protect cotton seedlings from the effects of the
herbicide clomazone (Command®), which is the herbicide of choice to control velvet leaf,
primrose, morning glory, and wild ppinsettia. Disulfoton is applied in-furrow with the seed,
while clomazone is applied as a band on top.  Roughly equal amounts of both the liquid and
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granular formulation are used by cotton growers, which is largely determined by the type of
equipment available to the grower. If either formulation were no longer available, growers
would incur substantial costs to convert their equipment to the other formulation. Also, because
aerial applications are not being made by growers, this method of application is not being
supported for reregistration and is being voluntarily cancelled.

       Alternatives to disulfoton use on cotton include phorate and aldicarb.  However, phorate,
which is applied as a granular formulation, is not as efficacious against thrips; and aldicarb,
which is very effective against thrips, does not act as a safener. Although use of disulfoton on
cotton has been declining, due to the introduction of genetically modified glyphosate tolerant
(RoundUp-Ready®) cotton, the percentage of acreage that can be planted with glyphosate
tolerant cotton is limited. Therefore, disulfoton is still important in areas that use clomazone for
weed control.

       The occupational risk estimates for this use are summarized below. As stated earlier, the
Agency has some uncertainty regarding risk estimates for crops where disulfoton is either shank
injected or applied in-farrow, such as cotton.  The Agency believes that these soil incorporated
methods of application result in less exposure to the applicator than does the groundboom or
tractor spreader methods, from which the estimated risks are derived.
Scenario
Aerial (SLN)
(Voluntary Cancellation)
Groundboom
Tractor-Drawn Spreader
Worker MOEs with Engineering Controls
Mixer/Loader
15
18
320
Applicator
25
(27)
(37)
REI
48/72 hours
( ) Indicates risk estimate for an applicator in an enclosed cab with a dust/mist respirator

       Cotton Decision:  Use of both the liquid and granular formulation on cotton are eligible
for reregistration. Also, labeling shall specify at-plant and in-furrow applications only, and for
use as safener, which reflects current agricultural practice.  Because disulfoton applications are
to be limited to at-plant and in-furrow as a safener, the current REI of 48/72 hours is still
protective and shall remain. Also, because aerial application to cotton is no longer being made
by growers, it is not being supported for reregistration.  Therefore, labels for disulfoton use on
cotton use will need to be amended to prohibit aerial application, including the 24(c) SLN
registration for aerial use in Texas. Moreover, to help mitigate ecological risk concerns, the
technical registrant removed foliar application from the Section 3 disulfoton labels, and reduced
the number of soil applications from three to one per year at a rate of 1 Ib ai/A.

       Peanuts

       Only the granular formulation of disulfoton is registered for use on peanuts. Based on
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 1987 to 1998 usage data, a weighted average of 47,000 Ib ai of disulfoton was applied annually
 to peanuts, which accounts for approximately 3% of the crop being treated. In the year 2000,
 disulfoton use on peanuts was reported in Alabama, Georgia, North Carolina, and Oklahoma.
 Disulfoton is applied in-furrow or as a soil incorporated side-dressing to control thrips and
 aphids.  Since the time the occupational risk assessment was prepared, Bayer, the technical
 registrant, had reduced the maximum application rate for the Section 3 registration from 2 Ibs
 ai/A to 1 Ib ai/A. Moreover, North Carolina has also voluntarily agreed to reduce the maximum
 application rate to 1 Ib ai/A for their 24(c) SLN registration. The occupational risk estimates
 based on the 1 Ib ai/A rate are summarized below. Also, the Agency has some uncertainty
 regarding risk estimates for crops where disulfoton is either shank injected or applied in-furrow,
 such as peanuts.  The Agency believes that these soil incorporated methods of application result
 in less exposure to the applicator than does the groundboom or tractor spreader methods, from
 which the estimated risks are derived.
Scenario
Tractor-Drawn Spreader
Worker MOEs with Engineering Controls
Loader
800
Applicator
(91)
REI
48/72 hours
 ( ) Indicates risk estimate for an applicator in an enclosed cab with a dust/mist respirator

       Peanuts Decision;  With the reduction of the maximum application rate for disulfoton
 use on peanuts, the corresponding MOEs for loaders and applicators are near or above the target
 MOE of 100, and are therefore not of concern to the Agency. Hence, use of the granular
 formulation on peanuts is eligible for reregistration. Because disulfoton applications are soil
 directed, the REI remains at 48/72 hours. The technical registrant has reduced the maximum
 application rate on Section 3 labels from 2 Ib ai/A to 1 Ib ai/A. Similarly, North Carolina has
 also voluntarily agreed to reduce the maximum application rate to 1 Ib ai/A for their 24(c) SLN
 registration; however, in accordance with the current 24(c) registration, two applications of
 disulfoton on peanuts is still permitted.

       Peppers

       Both the liquid and granular formulations are registered for use on a variety of peppers.
 The liquid registration is limited to a 24(c) SLN registration in California, where it is applied to
 the soil by shank injection.  This is the.application method of choice in California, because
 growers are not equipped to apply the granular formulation.  Based on 1987 to 1998 usage data,
 a weighted average of 4,000 Ib ai of disulfoton was applied annually to chili peppers, which
 accounts for approximately 25% of the crop being treated. Although a significant percentage of
peppers grown in the US are harvested in New Mexico and California, peppers are also grown in
other regions of the country. For instance,  USD A NASS data for the year 2000 indicate that
New Mexico harvested 57% of the chili peppers produced in the US, and California harvested
41% of the bell peppers produced in the US.  These figures indicate that a considerable amount
of peppers are grown outside these states as well. Most of the use of the liquid formulation is in
the Salinas Valley of California where disulfoton is used as a rescue remedy to control the green
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peach and cabbage aphid and the garden symphylan, a non insect pest.  The green peach aphid
vectors for several mosaic viruses lethal to pepper plants. The granular formulation, which is
used outside California, is applied in a soil incorporated band.

       Registered alternatives to disulfoton on peppers include imidacloprid, diazinon,
dimethoate, malathion, chlorpyrifos, oxydemeton-methyl, and pyrethrins.  Neither diazinon nor
malathion is effective against the green peach aphid.  Dimethoate is an inexpensive, frequently
used alternative, but it is no longer effective for aphid control in some areas of California and
New Mexico. Use of imidacloprid is increasing, but it does not provide effective control in some
parts of California. Chlorpyrifos is toxic to beneficial insects and also causes phytotoxicity at
the high rates required to control the cabbage aphid. Pyrethroids are not often used, because they
are not compatible with integrated pest management (IPM) programs. Therefore, the Agency
believes that there is a critical need for disulfoton use on peppers.

       As mentioned previously, private growers and commercial applicators hi the Salinas
Valley generally treat fewer acres per day than was assumed in the occupational risk assessment.
To assess risk based on typical current practices hi California, the Agency adjusted worker
MOEs in  the table below for the groundboom scenario to reflect the assumption that no more
than 40 acres are treated per day for peppers. MOEs for the granular tractor drawn spreader
scenario were not adjusted because it is primarily used outside California. Also, the Agency has
some uncertainty regarding risk estimates for crops where  disulfoton is either shank injected or
applied in-furrow, such as peppers. The Agency believes that these soil incorporated methods of
application result in less exposure to the applicator than does the groundboom or tractor spreader
methods,  from which the estimated risks are derived.
Scenario
Groundboom
Tractor-Drawn Spreader
Worker MOEs with Engineering Controls
Mixer/Loader
46
400
Applicator
(66)
(45)
REI
48/72 hours •
( ) Indicates risk estimate for an applicator in an enclosed cab with a dust/mist respirator
MOEs for the groundboom scenario are adjusted to reflect 40 acres treated/day

       Pepper Decision; Use of both the liquid and granular formulations on peppers are
eligible for reregistration. Because the liquid formulation is used exclusively in California, its
use is limited to an existing FIFRA 24(c) SLN registration in California, which reflects current
agricultural practice.  Also, because disulfoton applications are soil directed, the REI remains at
48/72 hours.

       Potatoes

       Both the liquid and granular formulations of disulfoton are registered for use on potatoes
to control aphids.  The liquid is mainly used hi the Pacific Northwest (PNW) (i.e.," Oregon,
Idaho, Washington, and Utah), where it is predominantly applied either aerially or by
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 chernigation (sprinkler irrigation) as an alternative to methamidophos (Monitor®), the pesticide
 of choice.  The liquid formulation is generally applied as a foliar application for late-season
 aphid control in sensitive areas where growers cannot aerially apply methamidophos. The
 granular formulation appears to be used mostly outside the PNW, where it is applied to the soil
 and incorporated. Based on 1987-1998 usage data, an average of 4% of the nations potato
 acreage were treated with disulfoton. However, use of disulfoton on potatoes in recent years
 appears to be declining with only about 1% of the crop treated nationally in 1999.  In Idaho,
 however, disulfoton use is slightly higher than the national average where 4% of the total potato
 acres grown were treated.

       There are a number of alternative pesticides that are available that can be applied by
 chemigation to control aphids, which include pymetrozine, thiomethoxam (late-season),
 imidacloprid (early-season), and methamidophos.  Methamidophos (Monitor®), the pesticide of
 choice for aerial applications is  available to control aphids via chemigation. Imidacloprid can be
 applied at planting for control of early to mid-season aphid and Colorado potato beetle
 infestations. Both pymetrozine  and thiomethoxam can be applied by chemigation, and are
 effective at late-season aphid control. Further, pymetrozine is less expensive than disulfoton;
 however, no cost data were available for thiomethoxam.  Because pymetrozine  and
 thiomethoxam are relatively new, they have yet to be widely used; however, efficacy field trials
 show promising results for aphid control.  Moreover, the Agency believes that the economic loss
 resulting from substituting disulfoton with either methamidophos or the other alternatives
 mentioned  would cause negligible economic impact to the overall potato industry. Because of
 the availability of these alternatives, which may be contributing to the decline in disulfoton use,
 and the negligible economic impact to the industry, the Agency believes that potato growers no
 longer have a critical need for disulfoton.
Scenario
Aerial (liquid)
(East of the Rockies)
Groundboom
Chemigation
Aerial (granular)
Tractor-Drawn Spreader
Worker MOEs with Engineering Controls
Mixer/Loader
21
15
Applicator
35
(22)
3.5
61
270
2.1
(31)
REI
20 days
(Foliar Application)
37 days
(Foliar Application)
48/72 hours
(Soil Directed
Application)
( ) Indicates risk estimate for an applicator in an enclosed cab with a dust/mist respirator

       Potato Decision:  Use of both the liquid and granular formulations are to be phased out
by June 2005 to allow growers time to transition to the newer and safer alternatives. In the
interim, the REI for foliar application to potatoes is to be extended to 37 days for overhead
sprinkler irrigation and groundboom applications, and 20 days for aerial applications East of the
Rockies. For disulfoton applications that are soil directed, the REI remains at 48/72 hours.
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       Also, to help further mitigate occupational and ecological risks, the technical registrant
has reduced the total number of soil applications from two to one per year; has discontinued all
foliar application West of the Rockies, except overhead sprinkler irrigation (chemigation); and
reduced the maximum application rate from 3 to 0.5 Ib ai/A for foliar applications East of the
Rockies.

       Radish Grown for Seed

       Both the liquid and granular formulations are registered for use on radish grown for seed
in Washington only through a 24(c) SLN registration.  As part of this registration, disulfoton use
is limited to the Columbia River Basin in Washington to control cabbage and turnip aphids,
which are a pest not seen in other areas that can cause premature plant death and crop loss. Both
formulations are applied to the soil and are either shank injected or soil incorporated.  In the year
2000, only about 635 acres total of this crop was produced. Even though it is a minor crop, it is
an economically important crop for growers in the Columbia River Basin, and disulfoton
provides a niche use to this industry.

       The only registered alternatives available to growers are pirimicarb, chlorpyrifos, and
pymetrozine. Pirimicarb is used solely to control late-season aphid infestations; chlorpyrifos
cannot be used during bloom when aphids can occur; and pymetrozine is more expensive than
disulfoton and does not provide good lower canopy control. Another advantage of disulfoton is
that it allows predatory  and parasitic insects to develop in the seed radish fields.

       The occupational risk estimates for this use are summarized below. As stated earlier, the
Agency has some uncertainty regarding risk estimates for crops where disulfoton is either shank
injected or applied in-furrow, such as radish. The Agency believes that these soil incorporated
methods of application result in less exposure to the applicator than does the groundboom or
tractor spreader methods, from which the estimated risks are derived.
Scenario
Groundboom
Tractor-Drawn Spreader
Worker MOEs with Engineering Controls
Mixer/Loader
23
400
Applicator
(33)
(45)
REI
48/72 hours
 ( ) Indicates risk estimate for an applicator in an enclosed cab with a dust/mist respirator

        Radish Grown for Seed Decision: Use of both the liquid and granular formulations on
 radish grown for seed are eligible for reregistration, through the existing FIFRA 24(c) SLN
 registration in Washington only. Because disulfoton applications are soil directed, the REI
 remains at 48/72 hours.

        Clover Grown for Seed

        Only the granular formulation is registered for use on clover grown for seed in

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Washington only through a 24(c) SLN registration. One soil directed application of disulfoton is
made per crop season with a tractor drawn spreader to control aphids and mites. The
occupational risk estimates for this use are summarized below.  Because the occupational risks
are low, information on the benefits associated with this use was not collected.
Scenario
Tractor-Drawn Spreader
Worker MOEs with Engineering Controls
Loader
800
Applicator
(91)
REI
48/72 hours
( ) Indicates risk estimate for an applicator in an enclosed cab with a dust/mist respirator

       Clover Grown for Seed Decision: The MOEs for loaders and applicators are near or
above the target MOE of 100, and are therefore not of concern to the Agency. Hence, use of the
granular formulation on clover grown for seed is eligible for reregistration, through the existing
FIFRA 24(c) SLN registration in Washington only. Because disulfoton applications are soil
directed, the REI remains at 48/72 hours.

       Coffee Trees

       The  granular formulation is registered for use in Puerto Rico only on coffee trees.
Disulfoton is applied to the soil by custom applicators only using a bucket and spoon at a rate of
8.3 Ibs ai/A. This rate is much a higher rate than that used for most other crops, but is validated
by efficacy data. The benefits associated with the use of disulfoton on coffee trees in Puerto
Rico are high, largely because of the need to control leafrniners, which can cause up to a 40%
reduction in yield. The only alternatives available to growers are aldicarb and azadirachtin;
however, azadirachtin does not have the residual activity needed to control leafrniners.

       The  occupational risk estimates for handling and applying disulfoton to coffee trees are
summarized below. The Agency assessed risks using two application methods: hand application
with a bucket and spoon with PPE, which is currently used by custom applicators in Puerto Rico;
and a tractor drawn spreader with engineering controls, which serves as a surrogate for other
potential application methods.  The Agency believes that risks can be reduced by use of a closed
loading/transfer system, with performance specifications similar to the device currently under
development by Tuthill Sotera in cooperation with the North Carolina Cooperative Extension
Service for use on Christmas trees. For comparison purposes, assuming this closed
loading/transfer device being developed will provide at least the  same level of protection as a
closed system currently available for tractor drawn spreaders, the MOE for an individual loading
the granulars with a closed transfer handheld device could be as high as 1500, based on the
individual applying up to 5 acres in a day. The Agency acknowledges that this estimate does not
include the exposure the same individual would received from also applying the chemical with
this device, because data to complete  this  analysis is not yet available. However, the Agency
expects that the protection provided by this type of device will be significantly better than the
current bucket and spoon application practice.
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Scenario
Bucket & Spoon
Tractor-Drawn Spreader
Worker MOEs
Loader
Applicator
0.2 - 0.4 [Minimum PPE]
96 [Eng. Controls]
(11)
REI
48/72 hours
( ) Indicates risk estimate for an applicator in an enclosed cab with a dust/mist respirator

       Coffee Tree Decision; Use of the granular formulation on coffee trees in Puerto Rico  .
only is eligible for reregistration provided that a closed transfer system is implemented by June
2004 and the REI remains at 48/72 hours.

       Christmas Trees (Fraserfirs)

       Only the granular is registered for use on conifers raised for the Christmas tree market.
There is also a 24(c) SLN registration in North Carolina for use of disulfoton at a rate of 4.5 Ibs
ai/A to control balsam wooly algedid and spruce spider mite on Fraser firs. The Section 3
registration is for a rate of 3.75 to 7.5 grams per foot of tree height or 2.5 oz/inch of tree
diameter at 4 feet above ground (diameter chest height), which extrapolates to 78 Ib ai/A.
According to the National Christmas tree association, disulfoton is used on firs grown for
Christmas trees in 16 states. North Carolina represents the greatest use, with 60,000 Ibs ai
applied annually and 65% of the crop being treated. The target pests named above cause
significant crop  damage, resulting in downgrading of trees and reduced sale value. In cases of
severe pest damage,  trees must be held over for an additional year, at a cost to the grower, or
infested trees must be destroyed.

       Disulfoton is applied at bud break in early spring, followed by foliar applications of
chlorpyrifos and esfenvalerate. Chlorpyrifos  and esfenvalerate must be foliarly-applied by a
commercial applicator by mist blower or high-powered hose sprayer. Foliar applications are
problematic because they  are usually uneven, which significantly affects efficacy.  Further, the
chlorpyrifos foliar spray is phytotoxic in some situations, and although esfenvalerate controls the
balsam wooly adelgid to a limited extent, it allows the spider mite populations to increase.  In
comparison, disulfoton controls both the balsam twig aphid and spruce spider mite, while
conserving beneficial insect predators. This information indicates that the need for disulfoton is
critical, especially for use on Fraser firs in North Carolina, because firs are a  high value
perennial crop.

       The occupational risk estimates for the predominant application methods used in North
Carolina are summarized below, and represent the worse case for use on firs. The Agency
believes that risks can be reduced by use of a closed loading/transfer  system currently under
development by Tuthill Sotera in cooperation with the North Carolina Cooperative Extension
Service for use on Christmas trees.
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Scenario
Bucket & Spoon
Tractor-Drawn Spreader
(Motorbike)
Worker MOEs
Loader
Applicator
0.4 - 0.7 [Minimum PPE]
280 [Eng. Controls]
23 [Maximum PPE]
REI
48/72 hours
       Christmas Tree Decision;  Use of the granular formulation on Christmas trees is eligible
for reregistration, provided the Section 3 label maximum application rate is reduced to 4.5 Ib
ai/A, and use is limited to firs, and a closed transfer system is implemented by June 2002, and
confirmatory exposure data for loader/applicators demonstrate that exposure and risk are
comparable to other high benefit scenarios. Also, disulfoton must be soil incorporated, watered
in, or applied to areas with permanent groundcover. Because disulfoton applications are soil
directed, the REI remains at 48/72 hours.

       Commercially Grown Ornamentals

       Only the granular formulation is registered for use on numerous species of ornamental
plants, including shrubs, trees, flowers and groundcover, and potted ornamental plants (field or
nursery stock). The current label specifies application rates of 3.75 to 7.5 grams  per foot of
height for a tree or shrub; 2.5 oz per inch of trunk diameter measured 4 feet from the ground for
trees; or 5 Ib product (0.75 Ib a.i.) per 1000 linear feet of row. For purposes of risk assessment,
the Agency has converted these rates to 37 Ib ai/A for trees, 109 Ib ai/A for shrubs, and 29 Ib
ai/A for field grown ornamental flowers and groundcover.  The Agency also assessed risks based
on 13 Ib ai/A, the lowest rate that the American Nursery & Landscape Association stated was
necessary to ensure efficacy.

       There is very little documented use of disulfoton on ornamentals and many alternative
pesticides are available. Based on preliminary results of recent USDA NASS data for pesticide
use in the  nursery and floriculture industry, only 22 of 4,000 operations reported  use of
disulfoton. The California use reporting database also shows little use of the chemical for
ornamental plants. Moreover, after conducting exhaustive outreach to major states which
produce ornamentals, very little use was disclosed and many agricultural extension agents who
work with ornamental plants do not recommend use of disulfoton. Also, there are significant
uncertainties associated with potential post-application exposure from routine activities,  such as
transplanting.  To adequately assess risks for these type of activities, post-application exposure
monitoring, which include soil residue dissipation (OPPTS 875.2200) and dermal exposure
(OPPTS 875.2400) data, would need to be provided to the Agency. These data might indicate
the need for further REI restrictions.

       Given the limited use and availability of cost-effective efficacious alternatives, the
benefits of continued use are low, particularly when compared to the worker MOEs and
uncertainty associated with post-application activities and risks. Worker risk estimates for the
predominant use of disulfoton on field grown ornamental shrubs, trees, flowers, and groundcover
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at an application rate of 13 Ib ai/A are summarized below.
Scenario
Loading/Applying with
Scoop & Bucket
Loading/Applying with
Belly Grinder
Tractor-Drawn Spreader
Worker MOEs
Loader
Applicator
0.1 - 0.3 [Minimum PPE]
0.1 [Maximum PPE]
120 [Eng. Controls]
(14)
REI
48/72 hours
 [ ) Indicates risk estimate for an applicator in an enclosed cab with a dust/mist respirator

       Ornamentals Decision: Use of the granular formulation is to be phase out by June
 2005, because of the limited existing need and use of the chemical, and the absence of
 information on the benefits of its continued use. For disulfoton applications that are soil
 directed, the REI remains at 48/72 hours.

       E.     Labeling

       In order to remain eligible for reregistration, other use and safety information needs to be
 placed on the labeling of all end-use products containing disulfoton.  For the specific labeling
 statements, refer to Table 16 in Section V of this document.

              1.     Endangered Species Statement

       The Agency has developed the Endangered Species Protection Program to identify
 pesticides whose use may cause adverse impacts on endangered and threatened species, arid to
 implement mitigation measures that address these impacts. Disulfoton has potential to result in
 effects to several aquatic species, in the absence of additional safeguards.  EPA has adopted
 Reasonable and Prudent Measures (RPMs) provided by the U.S. Fish and Wildlife Service
 Biological Opinions and has or will implement these measures, as appropriate, through
 Endangered Species Interim Bulletins.

       The Endangered Species Protection Program as described in a Federal Register notice (54
 FR 27984-28008, July 3, 1989) is currently being implemented on an interim basis.  As part of
 the interim program, the Agency has developed County Specific Pamphlets that articulate many
 of the specific measures outlined in the Biological Opinions issued to date. The Pamphlets are
 available for voluntary use by pesticide applicators on EPA's website at www.epa.gov/esp.p,

              2.      Spray Drift Management

        The Agency has been working with the Spray Drift Task Force, EPA Regional Offices,
 State Lead Agencies for pesticide regulation, and other parties to develop improved spray drift
 management practices. The Agency has completed its evaluation of the new database submitted

                                            96

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by the Spray Drift Task Force and is developing policy on how to appropriately apply the data
and the AgDRIFT computer model to its risk assessments for pesticides applied by air, orchard
airblast, or ground hydraulic spray. After the policy is in place, the Agency may impose further
refinements in spray drift management practices to reduce off-target drift and risks associated
with aerial application or other application methods associated with drift, where appropriate.

       Based on these analyses, the Agency is in the process of developing more appropriate
label statements for spray, and dust drift control to ensure that public health, and the
environment are protected from unreasonable adverse effects. In August 2001, EPA published
draft guidance for label statements in a pesticide registration (PR) notice ("Draft PR Notice
2001 -X" http://wwwiepa.gov/ PR_Notices/#2001). A Federal Register notice was published on
August 22,2001 (http://www.epa.gov/fedrgstr) announcing the availability of this draft guidance
for a 90-day public comment period. After review of the comments, the Agency will publish
final guidance in a PR notice for registrants to use when labeling their products.

       In the interim, registrants may choose to use the proposed statements. Registrants should
read and refer to the draft PR notice to obtain a full understanding of the proposed guidance and
its intended applicability, exemptions for certain products, and the Agency's willingness to
consider other versions of the statements.

       Registrants may elect to adopt the appropriate sections of the proposed language below,
or a version that is equally protective, for their end-use product labeling for the purpose of
complying with the deadlines for label submission outlined in this document. The proposed
label language is as follows:

       For products applied outdoors as liquids:

       "Do not allow spray to drift from the application site and contact people, structures
       people occupy at any time  and the associated property, parks and recreation areas,
       nontarget crops, aquatic and wetland areas, woodlands, pastures, rangelands, or animals."

       "For ground boom applications, apply with nozzle height no more than 4 feet above the
       ground or crop canopy, and when wind speed is 10 mph or less at the application site as
       measured by an anemometer.  Use	(registrant to fill in blank with spray quality,
       e.g. fine or medium) or coarser spray according to ASAE 572 definition for standard
       nozzles or VlylD for spinning atomizer nozzles."

       "For aerial applications, the boom width must not exceed 75% of the wingspan or 90% of
       the rotary blade.  Use upwind swath displacement, and apply only when wind speed is  3 -
       10 mph as measured by an anemometer. Use	(registrant to fill in blank with spray
       quality, e.g. fine or medium)  or coarser spray according to ASAE 572 definition for
       standard nozzles or VMD for spinning atomizer nozzles. If application includes a no-
       spray zone, do not release spray at a height greater than 10 feet above the ground or the
       crop canopy."
                                           97

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      For overhead chemigation:

      "Apply only when wind speed is 10 mph or less."

      On all product labels:

      "The applicator also must use all other measures necessary to control drift."
      "For ground rig applications, apply product no more than 4 feet above the ground
      or the crop canopy, and only when wind speed is 10 mph or less at the application
      site as 'measured by an anemometer."

      "For aerial applications, use upwind swath displacement, and apply only when wind
      speed is 3 - 10 mph as measured by an anemometer.  If application includes a no-spray
      zone, do not release dust at a height greater than 10 feet above the ground or the crop
      canopy."

      "The applicator also must use all other measures necessary to control drift."

      For hand-applied products, including home and garden products, to he applied as sprays
      or dusts:

      "Do not allow spray or dust to drift from the application site, and contact people,
      structures people occupy at any time, and the associated property, parks and recreation
      areas, nontarget crops, aquatic and wetland areas, woodlands, pastures, rangelands, or
      animals. Apply only when wind speed is not more than 10 mph. For sprays, apply
      largest size droplets possible."

      Alternatively, registrants may elect to use the following language, which is the current
Agency policy on drift labeling:

      For products that are applied outdoors in liquid sprays (except mosquito adulticides").
      regardless of application method, the following must be added to the labels:

      "Do not allow this product to drift."

      The Agency recognizes that the above option does not address other application types.
Registrants may therefore wish to adapt some variation of the old, and proposed new language
for their particular products,  depending on their application methods.

       F.     Disulfoton Risk Mitigation Summary

       Based on the rationale for the interim decisions associated with the use of disulfoton, the
following risk mitigation measures are also necessary  to be incorporated in their entirety into
labels for disulfoton-containing products in order for disulfoton to be eligible for reregistration.
                                           98

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Specific language of these revisions is set forth in the summary tables ,of Section V of this
document.  Likewise, the data required to be provided to the Agency to confirm these regulatory
decisions are also listed in Section V.

       Dietary Risk

•      No label changes are necessary, however certain confirmatory data listed in Section V is
       required.

       Residential Risk

       Only end-use products containing 2% active ingredient or less are eligible for
reregistration. The following measures are necessary to mitigate residential risk:

•      Limit maximum label rates for disulfoton packaged for hand application with a self
       .contained measuring cup/lid to 0.3 Ib ai/1000 ft2 for use on flowerbeds; 0.01 Ib ai/4 ft
       bush for use on shrubs; and 0.0013 Ib ai/bush for use on rose bushes.

•      Limit the maximum label rate for disulfoton packaged for application with a push type
       spreader to 0.3 Ib ai/1000 ft2.  Products to be applied by this method do not need to be in
       child resistant packaging, and commercial use of this product is prohibited.

•      Prohibit application of disulfoton with a belly grinder.

•      Prohibit application to flower gardens and ornamental shrubs with a spoon, measuring
       scoop, shaker can, or by hand, unless the packaging and method of application of the
       end-use product conforms with the performance of a measuring cup  and lid packaging
       currently manufactured for the Bayer Advanced Garden 2-in-l  Systemic Rose and
       Flower Care® Disulfoton 1% granular product.

•      Package all products marketed and labeled for hand application in child resistant
       packaging with a self-contained measuring device, which serves as the container lid and
       clearly measures the quantity to be applied. Products marketed and labeled for
       application with a push type spreader do not need to be in child resistant packaging, but
       must be labeled "not for application by hand." Commercial use of the homeowner
       product is prohibited.

•      Delete the following uses from all product labels:  all indoor uses, use in greenhouses,
       and use on home vegetable gardens, including use on spinach and tomatoes.

       Occupational Risk

       The following measures are necessary to mitigate  handler risk:
                                           99

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       Closed mixing/loading systems for liquid formulations by December 31, 2002;

•      Closed loading systems for granular formulations by June 2004;

       Enclosed cabs plus a dust-mist respirator for all ground equipment applicators;

•      Enclosed cockpits for all aerial applicators;

       Mechanical flaggers for aerial application; or the use of global positioning system (GPS)
       equipment that negates the need for flaggers;

       When engineering controls are not feasible, handlers must wear maximum PPE (i.e.,
       double layer clothing, chemical-resistant gloves and footwear, and a dust-mist respirator);

•      Use on cotton is limited to at plant, in furrow, and use as a herbicide safener only;

•      Reduction of maximum application rate from 2 Ib ai/A to 1 Ib ai/A for beans and
       peanuts;

       For coffee and Christmas trees, application by open, handheld equipment, including belly
       grinders and bucket and spoon will be prohibited after June 2004. Where this is currently
       the application method of choice, growers will be allowed until June 2004 to transition to
       another method; and

       Use on barley, wheat, potatoes, and commercially grown ornamentals (field or nursery
       stock)  is phased out by June 2005.

       The following measures are necessary to mitigate risk to post-application workers:
       i                                                 •-                           	
       For soil directed application of the liquid formulation and for all granular formulations,
       the Worker Protection Standard designates the REI to be 48 hours, or 72 hours in regions
       where  the annual rainfall is less than 25 inches. These are the current REIs on disulfoton
       product labels.

       For foliar application of the liquid formulation, a 26 day REI is necessary for asparagus.
       Longer REIs are also necessary for foliar application to barley (16 days), wheat (13
       days),  and potatoes (20 or 37 days depending upon method of application). As
       mentioned above, the uses on barley, wheat, potatoes, and ornamentals are to be phased
       out by June 2005.

       Ecological Risks

       The following measures are necessary to mitigate ecological risks.  Disulfoton is eligible
 for reregistration provided that:
                                           100

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•      A precautionary bee statement is added to all product labels for liquid formulations of
       disulfoton

•      Use is prohibited within a level, well maintained 25 foot vegetative buffer between
       treated fields and all permanent water bodies. (Refer to the March 2000 USDA Natural
       Resources Conservation Service  document: Conservation Buffers to Reduce Pesticide
       Losses for guidance.)

       No more than one application of disulfoton per calendar year for all crops, except for
       asparagus, barley, coffee, peanuts (North Carlina only), and potatoes (foliar application
       West of the Rockies only), for which no more than two applications of disulfoton per
       calendar year are permitted.

       Aerial application to cotton is prohibited;

       The maximum application rate for Christmas trees is reduced from 78 to 4.5 Ibs ai/A
       nationally, the use is limited to fir species only, and disulfoton is soil incorporated,
       watered in, or applied to areas with vegetative groundcover.

•      Uses on barley, wheat, potatoes,  and ornamental plants, including trees, shrubs, and
       groundcovers (field or nursery stock), are phased out by June 2005.  The phase out of
       these uses addresses ecological, as well as worker and  drinking water risks1 of concern.

       Eligible Uses

       The following uses are eligible for reregistration, pending consideration of the
cumulative assessment for the OPs:

•      Asparagus: Liquid formulation only

•      Beans, lima and snap: Both the liquid and granular formulations

*      Cabbage:  Both the liquid and granular formulations

       Cole Crops (broccoli, Brussels  sprouts, cauliflower): Both liquid (California only) and
       granular formulations

•      Lettuce: Liquid formulation only; California only

       Peppers:  Both the liquid and granular formulations

•      Peanuts: Granular formulation only

       Cotton:  Both the liquid and granular formulations
                                           101

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Radish Grown for Seed:  Both the liquid and granular formulations

Clover Grown for Seed:  Granular formulation only

Coffee Trees:  Granular formulation only

Christmas Trees:  Granular formulation only

Uses to be Phased Out

Barley and Wheat: Both the liquid and granular formulations

Ornamentals: Granular formulation only for field grown trees, shrubs, flowers and
groundcover, and potted ornamentals (field or nursery stock)

Potatoes: Both the liquid and granular formulations
                                   102

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V.     What Registrants Need to Do

       In order to be eligible for reregistration, registrants need to implement the risk mitigation
measures outlined in Section IV and submit the following:

       A.    Data Call-in Responses

       For disulfoton technical grade active ingredient products, registrants need to submit the
following items.

       Within 90 days from receipt of the generic data call-in (DCI):  (1) completed
response forms to the generic DCI (i.e., DCI response form and requirements status and
registrant's response form); and (2) any time extension and/or waiver requests with a full written
justification.

       Within the  time limit specified in the generic DCI: (1) cite any existing generic data
which address data requirements or submit new generic data responding to the DCI.

       Please contact Christina Scheltema at (703) 308-2201 with questions regarding generic
reregistration and/or the DCI. All materials submitted in response to the generic DCI should be
addressed as follows:
Bv US mail:
Document Processing Desk .(DCI/SRRD)
Christina Scheltema
US EPA (7508C)
1200 Pennsylvania Ave., NW
Washington, DC 20460
By express or courier service:
Document Processing Desk (DCI/SRRD)
Christina Scheltema
Office of Pesticide Programs (7508C)
Room 266A, Crystal Mall 2
1921 Jefferson Davis Highway
Arlington, VA 22202
       For products containing the active ingredient disulfoton, registrants need to submit the
following items for each product.

       Within 90 days from the receipt of the product-specific data call-in (PDCI): (1)
completed response forms to the PDCI (i.e., PDCI response form and requirements status and
registrant's response form); and (2) any time extension or waiver requests with a full written
justification.

       Within eight months from the receipt of the PDCI:  (1) two copies of the confidential
statement of formula (EPA Form 8570-4); (2) a completed original application for reregistration
(EPA Form 8570-1) (Indicate on the form that it is an "application for reregistration");
(3) five copies of the draft label incorporating all label amendments outlined in Table 16 of this
document; (4) a completed form certifying compliance with data compensation
requirements (EPA Form 8570-34); (5) if applicable, a completed form certifying compliance
                                          103

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with cost share offer requirements (EPA Form 8570-32); and (6) the product-specific data
responding to the PDCI.

       Please contact Jane Mitchell at (703) 308-8061 with questions regarding product
reregistration and/or the PDCI. All materials submitted in response to the PDCI should be
addressed:
Bv US mail:
Document Processing Desk (PDCI/PRB)
Jane Mitchell
US EPA (7508C)
1200 Pennsylvania Ave., NW
Washington, DC 20460
Bv express or courier service only:
Document Processing Desk (PDCI/PRB)
Jane Mitchell
Office of Pesticide Programs (7508C)
Room 266A, Crystal Mall 2
1921 Jefferson Davis Highway
Arlington, VA 22202
       B.    Manufacturing-Use Products

       Generic Data Requirements for Disulfoton

       The generic database supporting the reregistration of disulfoton for the above eligible
uses has been reviewed and determined to be substantially complete, except for the following
additional required confirmatory data:

1. Anaerobic Aquatic Metabolism (OPPTS 835.4400) (for parent, disulfoton sulfone, and
disulfoton sulfoxide)

2. Aerobic Aquatic Metabolism (OPPTS 835.4300) (for parent, disulfoton sulfone, and
disulfoton sulfoxide)

3. Mobility/Leaching and Absorption/Desorption (OPPTS 835.1240) (for parent, disulfoton
sulfone, and disulfoton sulfoxide)

4. Terrestrial Plant Toxicity, Tier 1, Seedling Emergence (OPPTS 850.4100) and Vegetative
Vigor (OPPTS 850.4150) for a typical liquid product, such as Di-Syston 8EC.

5. Certified Limits (OPPTS  830.1750)

6. UV/Visible Absorption of the PAI (OPPTS 830.7050)

7. Applicator Exposure Monitoring - Dermal Exposure, Outdoor (OPPTS 875.1100) and
Applicator Exposure Monitoring, Inhalation Exposure, Outdoor (OPPTS 875.1300)
for the following scenarios:
       - Liquid formulation, groundboom, enclosed cab + respirator
       - Granular formulation, tractor drawn spreader, enclosed cab + respirator
                                         104

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8.  Mixer/Loader/Applicator Exposure Monitoring, Dermal and Inhalation Exposure, Outdoor
(OPPTS 875.1100 and 1300) for the following scenarios:
       - Handheld closed loading, transfer, delivery system (NC Applicator)
       - Motorcycle mounted granular spreader with closed loading

9.  Mixer/Loader Exposure Monitoring - Dermal Exposure, Outdoor (OPPTS 875.1100) and
Mixer/Loader Exposure Monitoring - Inhalation Exposure, Outdoor (OPPTS 875.1300)
for the following scenarios:
       - Liquid closed loading system, e.g.,, SecureLink
       - Granular, closed loading system, e.g., Smartbox, Lock 'N Load

10. 21-Day Dermal Toxicology in Rats (OPPTS 870.3200)

11. Crop Field Trials for Cotton Gin Byproducts (OPPTS 860.1500)

12. Crop Field Trials for Lettuce (OPPTS 860.1500)

13. Storage Stability for all Livestock Commodities (OPPTS 860.1380)

14. Drinking Water Monitoring for Surface Water Sources (OPPTS 835.7200)

       Also, a Data Call-In Notice (DCI) was sent to registrants of OP pesticides currently
registered under FIFRA (August 6, 1999 64FR42945-42947, August 18 64FR44922-44923).
DCI requirements included acute, subchronic, and developmental neurotoxicity studies. The
developmental neurotoxicity study is scheduled to be submitted in November 2004, and the
registrant has satisfied the guideline requirements for the acute and subchronic neurotoxicity
studies in rats.

       Labeling for Manufacturing Use Products

       To remain in compliance with FIFRA, manufacturing-use product (MUP) labeling should
be revised to comply with all current EPA regulations, and address PR Notices and applicable
policies, as appropriate. The MUP labeling should bear the labeling contained in Table 16 at the
end of this section.

       C.    End-Use Products

       Additional Product-Specific Data Requirements

       Section 4(g)(2)(B) of FIFRA calls for the Agency to obtain any needed product-specific
data regarding the pesticide after a determination of eligibility has been made.  Registrants must
review previous data submissions to ensure that they meet current EPA acceptance criteria and if
not, commit to conduct new studies. If a registrant believes that previously submitted data meet
current testing standards, then the study MRID numbers should be cited according to the
                                          105

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instructions in the Requirement Status and Registrants Response Form provided for each
product.  A product-specific data call-in, outlining specific data requirements, accompanies this
IRED.                                                                        .     <

       Labeling for End- Use Products

       Labeling changes are necessary to implement the mitigation measures outlined in Section
IV above. Specific language to incorporate these changes is specified in Table 16 at the end of
this section.

       D.    Existing Stocks

       Registrants may generally distribute and sell products bearing old labels/labeling for 26
months from the date of the issuance of this IRED document.  Persons other than the registrant
may generally distribute or sell such products for 50 months from the date of the issuance of this
IRED document. However, existing stocks time frames will be established case-by-case,
depending on the number of products involved, the number of label changes, and other factors.
Refer to "Existing Stocks of Pesticide Products; Statement of Policy," Federal Register, Volume
56, No. 123, June 26, 1991.

       The Agency has determined that registrant may distribute and sell disulfoton products
bearing old labels/labeling for 26 months from the date of issuance of this IRED document.
Persons other than the registrant may distribute or sell such products for 50 months from the date
of the issuance of this IRED document. Registrants and persons other than the registrant remain
obligated to meet pre-existing label requirements and existing stocks requirements applicable to
products  they sell or distribute.

       E.    Labeling Changes Summary Table

       In order to be eligible for reregistration, all product labels are to be amended to
incorporate the risk mitigation measures outlined in Section IV. The following table describes
how language on the labels should be amended.
                                          106

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mize drippage to no more than 2 mL per disconnect. In addition, mixers and loaders must:
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equipment breakdown the following PPE:
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;over."
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lowing use sites must be deleted from all product labels: berries,
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protective, for their end-use product labeling.
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-------
VI. APPENDICES

      This section includes the Appendices that provide a listing of all related documents and
how to access them, a data call-in (DCI), and other information.

      All documents supporting the disulfoton IRED, in hard copy form, may be viewed in the
OPP Public Regulatory Docket or downloaded or viewed via the Internet at the following site:
www.epa. gov/pesticides/op. The OPP Public Docket is located in Room 119, Crystal Mall #2,
1921 Jefferson Davis Highway, Arlington, VA. It is open Monday through Friday, excluding
Federal holidays, from 8:30 a.m. to 4:00 p.m..

APPENDK A: Use Patterns Eligible for Reregistration

APPENDDT B: Generic Data Requirements and Studies Used

APPENDIX C: EPA's Technical Support Documents for Disulfoton

APPENDIX D: Bibliography

APPENDIX E: Generic Data Call-In

APPENDIX F:  Product-Specific Data Call-In

APPENDK G: EPA's Batching of Disulfoton Products for Meeting Acute Toxicity Data
       Requirements for Reregistration

APPENDIX H: List of Registrants Sent the Data Call-in

APPENDIX I: List of Electronically Available Forms
                                        119

-------
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-------
                                   APPENDIX B

                 Data Supporting FIFRA Guideline Requirements
                         for the Reregistration of Disulfoton

                               GUIDE TO APPENDIX B

       Appendix B contains listings of data requirements which support the reregistration for
active ingredients within the case 0102 covered by this Reregistration Eligibility Decision
Document. It contains generic data requirements that apply products within case 0102 in all
products, including data requirements for which a "typical formulation" is the test substance.

       The data table is organized in the following format:

       1.  Data Requirement (Column 1).  The data requirements are listed in the order in which
they appear in 40 CFR Part 158. the reference numbers accompanying each test refer to the test
protocols set in the Pesticide Assessment Guidelines, which are available from the National
Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161 (703) 487-4650.
In cases where there is a data gap, or where additional confirmatory data are required in the RED,
the new OPPTS guidelines are listed. These guidelines are also listed in the Generic DCI in the
RED.

       2.  Use  Pattern (Column 2). This column indicates the use patterns for which the data
requirements apply. The following letter designations are used for the given use patterns:

                          A     Terrestrial food
                          B      Terrestrial feed
                          C      Terrestrial non-food
                          D      Aquatic food
                          E      Aquatic non-food outdoor
                          F      Aquatic non-food industrial
                          G      Aquatic non-food residential
                          H      Greenhouse food
                          I      Greenhouse non-food
                          J      Forestry
                          K      Residential
                          L      Indoor food
                          M     Indoor non-food
                          N      Indoor medical
                          O      Indoor residential

       3.  Bibliographic citation (Column 3).  If the Agency has acceptable data in its files, this
column lists the identifying number of each study. This normally is the Master Record
Identification (MRID) number, but may be a "GS" number if no MRID number has been
assigned. Refer to the Bibliography appendix for a complete citation of the study.

                                         131

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                                  APPENDIX C

            EPA's TECHNICAL SUPPORT DOCUMENTS FOR DISULFOTON

        Additional documentation in support of this IRED is maintained in the OPP docket,
located in Room 119, Crystal Mall #2, 1921 Jefferson Davis Highway, Arlington, VA. It is open
Monday through Friday, excluding Federal holidays, from 8:30 am to 4 pm.

        The docket initially contained preliminary risk assessments and related documents as of
January 8, 1999.  Sixty days later the first public comment period closed.  EPA then considered
comments, revised the risk assessment, and added the formal "Response to Comments" document
and the revised risk assessment to the docket on March 10, 2000 for an additional public
comment period.  EPA revised the risk assessment again based on additional public comments
and new information, including voluntary changes to the disulfoton labels and voluntary test data.
EPA also reviewed benefits of disulfoton use  and any available alternatives. These final revised
risk assessments and benefits assessments form the basis of the regulatory decision described in
the IRED.

        All documents, in hard copy form, may be viewed in the OPP docket room or
downloaded or viewed via the Internet at the following site:

             www.epa.gov/pesticides/op

These documents include the following:

Human Health Risk Assessment Documents

1.       Christina Jarvis (USEPA/OPPTS/OPP/HED). Risk Assessment and Reregistration
        Eligibility Decision (RED) Documents for Disulfoton (Revised Risk Assessment, Phase
        4), February 10, 2000.

2.       David Anderson (USEPA/OPPTS/OPP/HED). Disulfoton: Revised (3rd) Report of the
        Hazard Identification Assessment Review Committee, April 10, 2001.

3.       Shanna Recore. (USEPA/OPPTS/OPP/HED). Review and Determination of Dermal
        (Hand and Forearm) and Inhalation Exposure to Disulfoton Resulting from Residential
        Application of Bayer Advanced Garden 2-in-l Systemic Rose and Flower Care to Shrubs
        and Flower Beds, June 6, 2001.

4.       Christina Jarvis (USEPA/OPPTS/OPP/HED). Revised Residential Exposure Assessment
        and Recommendations for the Reregistration Eligibility Decision (RED) Documents for
        Disulfoton, May 31, 2001 and addendum, August 9, 2002.
5.       Richard Griffin (USEPA/OPPTS/OPP/HED). Revised Occupational Exposure
       Assessment for the Reregistration Eligibility Decision Document for Disulfoton, June 15,
       2001.
                                         139

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6.     David Anderson (USEPA/OPPTS/OPP/HED).  Health Effects Division Toxicity Chapter
       for Reregistration Eligibility Decision (RED), June 25, 2001.

7.     Christina Jarvis (USEPA/OPPTS/OPP/HED). Disulfoton: Aggregate Risk Assessment,
       March 6,2002.

Environmental Fate and Ecological Effects Documents

8.     Henry Craven and James Wolf (USEPA/OPPTS/OPP/EFED). Reregistration Eligibility
       Document for Disulfoton, September 5, 2000 and its addendum March 25,2002.

9.     James Wolf (USEPA/OPPTS/OPP/EFED).  [Review of] The Interagency Study of the
       Impact of Pesticide Use on Ground-Water in North Carolina, August 1,2000.

10.    James Wolf.  (USEPA/OPPTS/OPP/EFED). Additional Information and Clarification for
       the Disulfoton RED [Review of California Surface Water Monitoring], October 20,2000.

11.    Henry Craven and Larry Turner (USEPA/OPPTS/OPP/EFED and FEAD). Endangered
       Species Addendum to EFED's Disulfoton Science Chapter, January 24, 2002

13.    James Wolf (USEPA/OPPTS/OPP/EFED). Disulfoton: Summary of Estimated Drinking
       Water Concentrations (EDWCs) for Use in the Human Health Risk Assessment, February
       25, 2002.

14.    Larry Turner (USEPA/OPPTS/OPP/FEAD).  Puerto Rican Plain Pigeon and Disulfoton,
       April 24,2002.

Benefits and Alternatives Analysis

15.    Nikhil Mallampalli. (USEPA/OPPTS/OPP/BEAD). Asparagus Benefits Assessment for
       Disulfoton, September 11,2001.

16.    Colwell Cook. (USEPA/OPPTS/OPP/BEAD). Benefits of Disulfoton on Selected
       Vegetable Crops and Cotton, September 27,2001.

17.    Nikhil Mallampalli. (USEPA/OPPTS/OPP/BEAD). Benefits Assessment for Disulfoton
       Use on Potatoes and Radish Seed, September 28,2001

18.    Colwell Cook. (USEPA/OPPTS/OPP/BEAD). Use of Disulfoton on Bell and Pimento
       Peppers, November 3, 2001

19.    Nikhil Mallampalli. (USEPA/OPPTS/OPP/BEAD). Cursory Assessment of Disulfoton
       Use in Coffee in Puerto Rico, November 26,2001.
                                       140

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20.     Colwell Cook. (USEPA/OPPTS/OPP/BEAD). Response to Questions Concerning
       Disulfoton Posed by Special Review and Reregistration Division [Regarding
       Ornamentals], December 17,2001.

21.     Colwell Cook. (USEPA/OPPTS/OPP/BEAD). Analysis of Disulfoton Use on Fraser Fir
       Trees in Western North Carolina. July 9, 2002. (Transmittal of OP Crop Use Matrices
       written in July 2000.)
                                        141

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142

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                            APPENDIX D

          MRID BIBLIOGRAPHY FOR DISULFOTON

                       GUIDE TO APPENDIX D

CONTENTS OF BIBLIOGRAPHY. This bibliography contains citations of all studies
considered relevant by EPA in arriving at the positions and conclusions stated elsewhere
in the Reregistration Eligibility Document. Primary sources for studies in this
bibliography have been the body of data submitted to EPA and its predecessor agencies
in support of past regulatory decisions.  Selections from other sources including the
published literature, in those instances where they have been considered, are included.

UNITS OF ENTRY. The unit of entry in this bibliography is called a "study." In the
case of published materials, this corresponds closely to an article.  In the case of
unpublished materials submitted to the Agency, the Agency has sought to identify
documents at a level parallel to the published article from within the typically larger
volumes in which they were submitted.  The resulting "studies" generally have a distinct
title (or at least a single subject), can stand alone for purposes of review and can be
described with a conventional bibliographic citation. The Agency has also attempted to
unite basic documents and commentaries upon them, treating them as a single study.

IDENTIFICATION OF ENTRIES. The entries in this bibliography are sorted
numerically by Master Record Identifier, or "MRID" number. This number is unique to
the citation, and should be used whenever a specific reference is required. It is not
related to the six-digit "Accession Number" which has been used to identify volumes of
submitted studies (see paragraph 4(d)(4) below for further explanation).  In a few cases,
entries added to the bibliography late in the review may be preceded by a nine character
temporary identifier. These entries are listed after all MRID entries. This temporary
identifying number is also to be used whenever specific reference  is needed.

FORM OF ENTRY. In addition to the Master Record Identifier (MRID), each entry
consists of a citation containing standard elements followed, in the case of material
submitted to EPA, by a description of the earliest known submission.  Bibliographic
conventions used reflect the standard of the American National Standards Institute
(ANSI), expanded to provide for certain special needs.

a     Author. Whenever the author could confidently be identified, the Agency has
      chosen to show a personal author.  When no individual was identified, the Agency
      has'shown an identifiable laboratory or testing facility as the author. When no
      author or laboratory could be identified, the Agency has shown the first submitter
      as the author.
                                  143

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b.    Document date. The date of the study is taken directly from the document. When
      the date is followed by a question mark, the bibliographer has deduced the date
      from the evidence contained in the document. When the date appears as (1999),
      the Agency was unable to determine or estimate the date of the document.

c.    Title. In some cases, it has been necessary for the Agency bibliographers to create
      or enhance a document title. Any such editorial insertions are contained between
      square brackets.

d.    Trailing parentheses. For studies submitted to the Agency in the past, the trailing
      parentheses include (in addition to any self-explanatory text) the following
      elements describing the earliest known submission:

      (1)     Submission date. The date of the earliest known submission appears
             immediately following the word "received."

      (2)     Administrative number. The next element immediately following the word
             "under" is the registration number, experimental use permit number,
             petition number, or other administrative number associated with the earliest
             known submission.

      (3)    -Submitter. The third element is the submitter. When authorship is
             defaulted to the submitter, this element is omitted.

      (4)     Volume Identification (Accession Numbers). The final element in the
             trailing parentheses identifies the EPA accession number of the volume ha
             which the original submission of the study appears.  The six-digit accession
             number follows the symbol "CDL," which stands for "Company Data
             Library."  This accession number is in turn followed by an alphabetic suffix
             which shows the relative position of the study within the volume.
                                  144'

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                 MRID BIBLIOGRAPHY FOR DISULFOTON

 00065495    Pickering,,Q.H.; Henderson, C.; Lemke, A.E. (1960) The Toxicity of Organic
             Phosphorus Insecticides to Different Species of Warm Water Fishes: Report No.
             9282. (U.S. Public Health Service, RA. Taft Sanitary Engineering Center,
             unpublished study including Chemagro Corp. summary; CDL:229299-A)

00073348     Hoffmann, K.; Weischer, C.H.; Luckhaus, G.; et al. (1975) S 276 (Disulfoton)
             Chronic Toxicity Study on Dogs (Two-year Feeding Experiment): Report No.
             5618; Report No. 45287. (Unpublished study received Dec 15,1976 under
             3125-58; prepared by Bayer, AG, W. Germany, submitted by Mobay Chemical
             Corp., Kansas City, Mo.; CDL:095640-N)

00077863     DeCino, T.J. (1963) Letter sent to Walter M. Zeck dated Mar 14,1963 [Toxicity
             and repellency data on Bayer compounds]: Report No. 11064. (Unpublished
             study, including letters dated Mar 12, 1963 from T.J. DeCino to Thaddeus Parr,
             Mar 28,1963 from W.M. Zeck to Farbenfabriken Bayer, A.G. and Apr 18,1963
             from T.J. DeCino to Walter M. Zeck, received Jul 31, 1972 under 3125-213;
             submitted by Mobay Chemical Corp., Kansas City, Mo.; CDL: 120480-H)

00095657     Lamb, D.W.; Nelson, D.L. (1971) Toxicity of ®Di-syston 15% Granular on
             Sorghum to Juvenile Bobwbite Quail under Simulated Field Conditions: Report
             No. 31135.  (Unpublished study received Nov 30, 1971 under unknown admin.
             no.; submitted by Mobay Chemical Corp., Kansas City, Mo.; CDL: 128321-A)

00095658     Lamb, D.W.; Nelson, D.L. (1971) Toxicity of ®Di-syston Spray Concentrate to
             Juvenile Bobwhite Quail and New Zealand Rabbits under Simulated Field
             Conditions: Report No. 31235. (Unpublished study received Nov 30,1971 under
             unknown admin, no.; submitted by Mobay Chemical Corp., Kansas City, Mo.;
             CDL: 128321-B)

00129385     Ross, F.; Tesh, J.; Seeker, R.; et al. (1982) S 276: Effects of Oral Administration
             upon Pregnancy in the Rabbit: LSR Report No. 82/BAG025/555; 82725.
             (Unpublished study received Jun 23, 1983 under 3125-183; prepared by Life
             Science Research, Eng., submitted by Mobay Chemical Corp., Kansas City, MO;
             CDL: 250642-B)

00129456     Mobay Chemical Corp. (1983) Oncogenicity Study of Technical Disulfoton on
             Mice. Interim rept. (Unpublished study received Jul 13,1983 under 3125-58;
             CDL:250706-A)

00129458     Lamb, D.; Hixson, E.; Breeden, B.; et al. (1983) Embryotoxic and Teratogenic
             Effects of Disulfoton: Study No. 81-611-02; 84055. (Unpublished study received
             Jul 13,1983 under 3125-58; submitted by Mobay Chemical Corp., Kansas City,
             MO; CDL:250706-C)

                                        145

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00139595     Mihail, F.; Lorke, D. (1978) S 276 (Disyston Active Ingredient) Acute Toxicity
             Studies: Report No. 7602; 66260. (Unpublished study received Jan 18, 1984 under
             7F1895; prepared by Bayer AG, W. Ger., submitted by Mobay Chemical Corp.,
             Kansas City, MO; CDL:072293-B)

00139603     Chen, H.; Hsueh, J.; Sirianni, S.; et al. (1981) Induction of sister-chromatid
             exchanges and cell cycle delay in cultured mammalian cells treated with eight
             organophosphorus pesticides. Mutation Research 88:307-316. (Submitter 86157;
             also In unpublished submission received Jan 18, 1984 under 7F1895; submitted by
             Mobay Chemical Corp., Kansas City, MO; CDL:072293-M)

00139609     Riccio, E.; Shepherd, G.; Pomeroy, A.; et al. (1981) Comparative studies between
             the S. cerevisiae D3 and D7 assays of eleven pesticides.  Taken from: Environ.
             Mutag. 3:327. (Abstract P63; submitter 86167; also In unpublished submission
             received Jan 18,  1984, submitted by Mobay Chemical Corp., Kansas City, MO;
             CDL: 072293-S)

00143401     Heimbach, F. (1983) Acute Toxicity of Disulfoton (Technical) to Water Fleas.
             Unpublished Mobay report 85916 prepared by Bayer AG.  10 p.

00143405     Leimkuehler, W.; Thornton, J. (1980) Hydrolysis of DI-SYSTON in Sterile
             Aqueous Buffer  Solutions. Unpublished Mobay report 68943 prepared by Mobay
             Chemical Corp.  21 p.

00145469     Puhl, R.; Hurley, J. (1979) Soil Adsorption and Desorption of DISYSTON.
             Unpublished Mobay report 66792 prepared by Mobay Chemical Corp. 17 p.

00145470     Obrist,  J. (1979) Leaching Characteristics of Aged DI-SYSTON Soil Residues.
             Unpublished Mobay report 67485 prepared by Mobay Chemical Corp. 15 p.

00147754     Thyssen, J. (1978) S 276: Acute Inhalation Toxicity Studies: Report No. 7827.
             Unpublished Mobay Study no. 66647 prepared by Bayer AG.  16 p.

00147886     Tesh, J.; Ross, F.; Seeker, R. et al (1982) S 276 : Effects of Oral Administration
             upon Pregnancy in the Rabbit: Report No. 82/BAG025/555. Unpublished report
             prepared by Life Sciences Research. 78 p.

00148217     Chevron Chemical Co. (1985) Discussion Sheet: Ortho 3-Way Rose and Flower
             Care: Particle Size Analysis—Response to EPA's Comments on Inhalation Studya.
             Unpublished study.  1 p.

00150088     Mobay Chemical Corp. (1984) Product Chemistry of Di-Syston Insecticide.
             Unpublished compilation. 90 p.
                                         146

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00153336    Sangha, G. (1985) Acute Inhalation Toxicity Study with Di-Syston 1% Granular
             on 18-4-8 Fertilizer in Rats: Study No. 85-041-10: Mobay Report No. 90449.
             Unpublished study prepared by Mobay Chemical Corp. 20 p.

00153339    Sangha, G. (1985) Acute Inhalation Toxicity Study with Di-Syston 2% Granular
             Dust in Rats: Study No. 85-041-09: Mobay Report No. 90572. Unpublished study
             prepared by Mobay Chemical Corp.  20 p.

00153518    Heimbach, F. (1982) Lab Form for the Test Procedure: "Acute Toxicity to Daphnia
             magna": Addendum to Mobay Report No. 85916: Raw Data for Acute Toxicity of
             Disulfoton to Water FleasO: 85-T-145: Incomplete unpublished study prepared by
             Bayer AG.  10 p.

00157511    Hixson, E.; Hathaway, T. (1986) Effect of Disulfoton (Di-Syston) on Reproduction
             in Rats: Study No.  82-671-02: Mobay Report No. 90965. Unpublished study
             prepared by Mobay Chemical Corp. 258 p.

00162338    Flucke, W. (1986) S 276 Technical: (Common Name:  Disulfoton, the Active
             Ingredient of Di-Syston): Study of Subacute Dermal Toxicity to Rabbits: Bayer
             Report No. 14747:  Study No. T 9020197. Unpublished Mobay Report No. 93096
             prepared by Bayer AG. 199 p.

00162859    Mobay Corp. (1986) Di-Syston: Residue Chemistry on Cotton: Brochure No.
             1442. Unpublished compilation. 97 p.

00163423    Schmidt, H. (1986) Bee Toxicity by U.S. Protocol: Honey Bee Residue Testing:
             Disyston on Alfalfa: Reports No. VAZ 16/85 and 86-T095. Unpublished Mobay
             reports 90831 and 93046 prepared by Bayer AG.  39 p.

0068268      Lamb, D.W.; Roney, DJ. (1972) Acute Toxicity of ®Di-syston Technical,
             Di-syston 15% Granular and Di-syston 6 Ibs/gal Spray Concentrate to Bluegill and
             Rainbow Trout: Report No. 34931. (Unpublished study received Sep 13,  1977
             under 3125-183; submitted by Mobay Chemical Corp., Kansas City, Mo.;
             CDL:231851-A)

0094233      Lamb, D.W.; Jones, R.E. (1973) Toxicity of ®Dasanit-®Disyston and
             Dasanit-Tilliam to Bobwhite Quail and Mallard Ducks: Report No. 38462.
             (Unpublished study received Jan 25, 1974 under 3125-252; submitted by Mobay
             Chemical Corp., Kansas City, Mo.; CDL:025811-F)

0095655      Shellenberger, T.E. (1969) Letter sent to D.L. Nelson dated Aug 11, 1969: Acute
             Toxicological Evaluations of Di-syston with Adult Bobwhite Quail: GSRI Project
             No. NC-301; 25525. Final rept. (Unpublished study received Mar 19, 1971 under
             unknown admin, no.; prepared by Gulf South Research Institute, submitted by
             Mobay Chemical Corp., Kansas City, Mo.; CDL:128228-A)
                                        147

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05008363    Hudson, R.H.; Haegele, M.A.; Tucker, R.K. (1979) Acute oral and percutaneous
             toxicity of pesticides to mallards: correlations with mammalian toxicity data.
             Toxicology and Applied Pharmacology 47(3):451-460.

15827000    Mobay Chemical Corp. (1986) Disyston: Residue Data: Unpublished Compilation.
             37 p.

16000000    Hudson, R.; Tucker, R.; Haegele, M. (1984) Handbook of Toxicity of Pesticides
             to Wildlife: Second Edition.  US Fish and Wildlife Service, Resource Publication
             No. 153.  91 p.

40042201    Lee, S.; Hanna-Bey, L.; Wood, S. (1986) Metabolism of Di-Syston in Soil: Rept.
             No. 94232.  Unpublished study prepared by Mobay Corp. 32 p.

40056700    Mobay Chemical Corp. (1987) Di-Syston--Magnitude of Residue on Asparagus:
             Data Submitted in response to the Registration Standard for Pesticides Containing
             Disulfoton,  December 1984.  Compilation of 1 study.

40056701    Brown, M. (1986) Di-Syston~Magnitude of Residue on Asparagus: Hazleton Job
             No. 6012-168.  Unpublished Mobay Project ID 1850 and Mobay Report No. 94210
             prepared by Hazleton Laboratories America, Inc. 55 p.

40071600    Mobay Chemical Corp. (1987) Reregistration Standard for Products Containing
             Disulfoton (Di-Syston): Acute Toxicity Reports. Compilation of 3 Studies.

40071601    Surprenant, D.  (1986) Acute Toxicity of Di-Syston to Mysid Shrimp (Mysidopsis
             bahia) under Flow-through Conditions: Laboratory Project ID: 91344: Bionomics
             Report #BW-86-7-2112.  Unpublished study prepared by Springborn Bionomics,
             Inc. 28 p.

40071602    Surprenant, D.  (1986) Acute Toxicity of Di-Syston to Sheepshead Minnow
             (Cyprinodon variegatus) under Flow-through Conditions:  Laboratory Project ID:
             91345: Bionomics Report #BW-86-7-2091. Unpublished study prepared by
             Springborn  Bionomics, Inc.  28 p.

40071603    Surprenant, D.  (1986) Acute Toxicity of Di-Syston to Estern Oysters (Crassostrea
             virginica): Laboratory Project ID: 91346: Report #BW-86-7-2060. Unpublished
             study prepared by Springborn Bionomics, Inc. 28 p.

40098001    Mayer F., Ellersieck M. (1986) Manual of Acute Toxicity: Interpretation and
             Database for 410 Chemicals  and 66 Species of Freshwater Animals. US Fish and
             Wildlife Service. Resource Publication  160.  579 p.
                                         148

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40116801    Lee, S.; Sandie, F.; Wood, S. (1987) Dissipation of Di-syston and its Oxidative
             Metabolites in Field Soil: Report Number 94328. Unpublished study prepared by
             Mobay Corp. 46 p.

40156601    Delk, J. (1986) Di-Syston~Magnitude of Residue on Lettuce: Laboratory Project
             ID: 6012-168: Mobay Project ID: 1612, 1613. Unpublished study prepared by
             Hazleton Laboratories America, Inc. 92 p.

40156602    Calovich, C. (1987) Di-Syston-Magnitude of Residue on Cabbage: Laboratory
             Project ID: 86-421 and 86-466: Mobay Project ID: 1004. Unpublished study
             prepared by En-Cas Analytical Labs. 126 p.

40156603    Calovich, C. (1987) Di-Syston~Magnitude of Residue on Cauliflower: Laboratory
             Project ID: 86-286 and 86-466: Mobay Project ED: 1005. Unpublished study
             prepared by En-Cas Analytical Labs. 71 p.

40156604    Calovich, C. (1986) Di-Syston~Magnitude of Residue on Brussels Sprouts:
             Laboratory Project ID: 86-475 and 86-479: Mobay Project ID: 1003. Unpublished
             study prepared by En-Cas Analytical Labs. 30 p.

40156605    Calovich, C. (1987) Di-Syston—Magnitude of Residue on Broccoli: Laboratory
             Project ID: 86-158 and 86-429: Mobay Project ID: 1002. Unpublished study
             prepared by En-Cas Analytical Labs. 57 p.

40156607    Calovich, C. (1987) Di-Syston-Magnitude of Residue on Soybeans: Laboratory
             Project ID: 2344: Mobay Project ID: 3616. Unpublished study prepared by
             Chemonics Laboratories. 55 p.

40156610    Brown, M. (1986) Di-Syston—Magnitude of Residue on Potatoes: Laboratory
             Project ID: 40540, 41700. Unpublished study prepared by Morse Laboratory, Inc.
             29p.

40156612    Bailey, S. (1986) Di-Syston—Aerial Drift Evaluation: Chemonics Laboratory
             Project ID: 1890: Mobay Project ID: 8600. Unpublished study prepared by New
             Mexico State University and Chemonics Inc. in cooperation with Mobay Corp.  47
             P-

40204301    Bailey, S. (1987) Di-Syston~Magnitude of Residue on Barley: ADC No. 950:
             Morse 42347. Unpublished Mobay report 91478 prepared by Analytical
             Development Corp. in cooperation with Morse Laboratories. 56 p.

40204302    Bailey, S. (1987) Di-Syston-Magnitude of Residue on Coffee: Morse 42315:
             Di-Syston Objective No. 3900.  Unpublished Mobay report 91497 prepared by
             Morse Laboratories, Inc. 40 p.
                                         149

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40204303    Bailey, S. (1987) Di-Syston—Magnitude of Residue on Tobacco: Morse
             DI-3823-86: Di-Syston Objective No. 3823. Unpublished Mobay report 94426
             prepared by Morse Laboratories, Inc. 77 p.

40204304    Calovich, C. (1987) Di-Syston-Magnitude of Residue on Cotton: Laboratoiy
             Project ID: DI-3718-86: Di-Syston Objective No. 3718. Unpublished Mobay
             report 91487 prepared by Chemonics Laboratories. 85 p.

40204305    Bailey, S. (1987) Di-Syston-Magnitude of Residue on Alfalfa: Morse 40960:
             Chemonics Rl-211. Unpublished study prepared by Morse Laboratories, Inc. in
             cooperation with Chemonics Laboratories. 72 p.

40204309    Bailey, S. (1987) Di-Syston—Magnitude of Residue on Tomatoes: Hazleton
             612108A: Di-Syston Objective No. 1810. Unpublished Mobay report 91474
             prepared by Hazleton Laboratories. 35 p.

40204310    Bailey, S. (1987) Di-Syston-Magnitude of Residues on Tomatoes and Tomato
             Processing Products: Hazleton 612108A: Di-Syston Objective No. 1810.
             Unpublished study prepared by Hazleton Laboratories America, Inc. 47 p.

40204311    Calovich, C. (1987) Di-Syston-Magnitude of Residue on Peanuts: Laboratory
             Project ID: DI-3631-86: Di-Syston Objective No. 3631. Unpublished Mobay
             report 91492 prepared by Chemonics Laboratories. 58 p.

40471102    Kesterson, A.; Ruzo, L.; Lawrence, L. (1987) Photochemical Degradation of
             Di-Syston in Aqueous Solution Under Natural Sunlight: Report No. 1119: Project
             No. 180. Unpublished Mobay Corporation Report No. 95065 performed by
             Pharmacology and Toxicology Research Laboratory.  40 p.

40471103    Jackson, S.; Kesterson, A.; Ruzo, L.; et al. (1987) Soil Surface Photolysis of
             Di-Syston in Natural Sunlight: Report No. 1123: Project No. 202. Unpublished
             Mobay Corporation Study No. 95066 performed by Pharmacology and Toxicology
             Laboratory. 42 p.

40471105    Hamann, S.; Olson, G.; Howard, J.; et al. (1987) Volatility of Di-Syston Under
             Field Conditions: Report No. 1131: Project No. 193. Unpublished Mobay
             Corporation study no. 95068 performed by Pharmacology and Toxicology
             Laboratory. 42 p.
                                                          <
40471106    Forbes, A. (1987) Uptake, Depuration and Bioconcentration of [Carbon
             14]-Di-Syston to Bluegill Sunfish ...  Unpublished Mobay Corporation study no.
             95078 performed by Analytical Bio-chemistry Laboratories, Inc.  43 p.
                                         150

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40471107    Hanlon, C.; Cain, K. (1987) Identification of Residues from Bluegill Sunfish
             Exposed to [Carbon 14]-Di-Syston: Laboratory Project ID DI-03-A. Unpublished
             Mobay Corporation study no. 95076. 24 p.

40495001    Putman, D. (1987) Sister Chromatid Exchange Assay in Chinese Hamster Ovary
             (CHO) Cells: Di-syston: Study No. T5196.334. Unpublished study prepared by
             Microbiological Associates, Inc. 31 p.

40561201    Pither, K. (1988) Di-Syston~Magnitude of Residues on Wheat and Wheat
             Processed Commodities: Laboratory Project ID DI302987R02. Unpublished
             Mobay Study No. 94723 prepared by McKenzie Labs., Inc. 127 p.

40638401    Yang, L. (1988) CHO/HGPRT Mutation Assay: Di-syston Technical: Study No.
             T5196.332. Unpublished study prepared by Microbiological Associates Inc. 33 p.

40768901    Leslie, W. (1988) Di-Syston-Magnitude of Residue on Peanut and Peanut
             Processed Products: Project No. DI-363186RO1: DI-SYSTON Objective No.
             3631.  Unpublished study prepared by McKenzie Laboratories, Inc.  148 p.

40939001    Krautter, G.; Marsh, J.; Downs, J.; et al. (1988) Metabolism of [Carbon
             14]Di-Syston in the Lactating Goat: Report No. 1159: Project No. 216.
             Unpublished study prepared by Pharmacology and Toxicology Research
             Laboratory. 62 p.

40939002    Krautter, G.; Marsh, J.; Downs, J.; et al. (1987) Quantitative Characterization of
             Residues in Tissues and Eggs of Laying Hens treated Orally for Three Consecutive
             Days with [Carbon]DiSyston-ethylene: Report No. 1130: Project No. 225.
             Unpublished study prepared by Pharmacology and Toxicology Research
             Laboratory. 97 p.

41224301    Shiotsuka, R. (1989) Subchronic Inhalation Toxicity Study of Technical Grade
             Disulfoton (DI-SYSTON) in Rats: Study No. 88-141-AU. Unpublished study
             prepared by Mobay Corp.  1272 p.

41585100    Mobay Corp. (1990) Submission of Metabolism Data to Support the Reregistration
             of Disulfoton Products. Transmittal of 2 studies.

41585101    Olson, G.; Lawrence, L. (1990) Aerobic Metabolism of [Carbon 14]DiSyston in
             Sandy Loam Soil: PTRL Report No.: 1229; PTRL Project No. 320; Mobay Report
             No. 99737. Unpublished study prepared by Pharmacology and Toxicology
             Research Laboratory.  58 p.

41585102    Olson, G.; Lawrence, L.-(1989) Anaerobic Metabolism of [Carbon 14]Di-Syston in
             Sandy Loam Soil: Report No.: 1212; Project No.: 321; Mobay Report No.: 99738.
             Unpublished study prepared by Pharmacology and Research Laboratory. 46 p.
                                         151

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 41850000     Mobay Corp. (1991) Submission of Data To Support the Reregistration of
              Disulfoton (Di-Syston): Toxicology Studies. Transmittal of 2 studies.

 41850001     Hayes, R. (1991) Chronic Feeding/Oncogenicity Study of Technical Disulfoton
              (Di-Syston) with Rats: Supplement: Lab Project Number: 90111. Unpublished
              study prepared by Mobay Corp. 65 p.

 41850002     Hayes, R. (1991) Chronic Feeding/Oncogenicity Study of Technical Disulfoton
              (Di-Syston) with Rats: Supplement: Lab Project No: 90111.  Unpublished study
              prepared by Mobay Corp. 618 p.

 41935801     Rhodes, J.; Schrier, L.; McAllister, W. (1990) Early Life-Stage Toxicity of Di-
              Syston Technical to the Rainbow Trout (Oncorhyn-chus mykiss) Under Flow-
              through Conditions: Final Report: Lab Project Number: 33896: 100350.
              Unpublished study prepared by Analytical Bio-chemistry Laboratories, Inc. 89 p.

 41935802     Blakemoer, G. Forbis, A. (1991) Chronic Toxicity of Di-Syston  Technical to
              Daphnia magna Under Flow-through test Conditions.  Project No. 38398: 101211.
              Unpublished study prepared by Analytical Biochemistry Laboratories Inc. 45 p.

 42229401     Eberhart, D. (1992) Di-Syston Exposure Estimate for Mixer/Loader and
              Applicators: Lab Project Number: 95625. Unpublished study prepared by Miles
              Inc. 20 p.

 42565101     Lee, S.; Hanna, L.; Johnston, K.; et al. (1985) Excretion and Metabolism of
              DI-SYSTON in Rats: A Supplement: Lab Project Number: 90946. Unpublished
              study prepared by Mobay Corp. 67 p.

 42582901     Parrish, J.; Yeager B.; Klienfelter, J. (1992) Effect of DiSyston Sulfoxide on
              Honey Bee Mortality: Lab Project Number: D1772901:103932.  Unpublished
              study prepared by Bio/West, Inc. 31 p.

 42582902     Parrish, J.; Yeager, B.; Klienfelter, J. (1992) Effect of Disyston-Sulfone on Honey
              Bee Mortality: Lab Project Number: DI772902: 103931.  Unpublished study
              prepared by Bio/West, Inc. 30 p.

 42585101     Stafford, T. (1992) DI-SYSTON Sulfone: A Subacute Dietary LC50 with Mallard
              Ducks: Lab Project Number: DI720801. Unpublished study prepared by Miles
              Inc. 36 p.

42585102     Stafford, T.; Reynolds, M. (1992) DI-SYSTON Sulfoxide: An Acute Oral LD50
              with Bobwhite Quil: Lab Project Number: DI711702. Unpublished study
             prepared by Miles Inc. 33 p.
                                         152

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42585103     Stafford, T.; Reynolds, M. (1992) DI-SYSTON Sulfone: An Acute Oral LD50
             with Bobwhite Quil: Lab Project Number: DI711703. Unpublished study prepared
             by Miles Inc. 33 p.

42585104     Stafford, T. (1992) DI-SYSTON Sulfoxide: A Subacute Dietary LC50 with
             Mallard Ducks: Lab Project Number: DI720802.  Unpublished study prepared by
             Miles Inc.  36 p.

42585105     Stafford, T. (1992) DI-SYSTON Sulfoxide: A Subacute Dietary LC50 with
             Bobwhite Quail: Lab Project Number: DI721702. Unpublished study prepared by
             Miles Inc.  36 p.

42585106     Stafford, T. (1992) DI-SYSTON Sulfone: A Subacute Dietary LC50 with
             Bobwhite Quail: Lab Project Number: DI721701. Unpublished study prepared by
             Miles Inc.  36 p.

42585107     Gagliano, G.; Roney, D. (1992) Acute Toxicity of Disyston-Sulfoxide Technical
             to the Bluegill under Static Renewal Conditions: Lab Project Number: DI810302.
             Unpublished study prepared by Miles Inc. 40 p.

42585108     Gagliano, G.; Bowers, L. (1992) Acute Toxicity of DI-SYSTON Sulfone
             Technical to the Bluegill under Static Renewal Conditions: Lab Project Number:
             DI810303. Unpublished study prepared by Miles Inc. 39 p.

42585109     Gagliano, G.; Roney, D. (1992) Acute Toxicity of DI-SYSTON Sulfoxide
             Technical to the Waterflea under Static Renewal Conditions: Lab Project Number:
             DI820702. Unpublished study prepared by Miles Inc. 3 8 p.

42585110     Gagliano, G.; Roney, D. (1992) Acute Toxicity of DI-SYSTON Sulfoxide
             Technical to the Rainbow Trout under Static Renewal Conditions: Lab Project
             Number: DI812202. Unpublished study prepared by Miles Inc. 39 p.  .

42585111     Gagliano, G.; Bowers, L. (1992) Acute Toxicity of DI-SYSTON Sulfone
             Technical to the Rainbow Trout under Static Renewal Conditions: Lab Project
             Number: DI812201. Unpublished study prepared by Miles Inc. 40 p.

42585112     Gagliano, G.; Bowers, L. (1992) Acute Toxicity of DI-SYSTON Sulfone
             Technical to the Waterflea under Static Conditions: Lab Project Number:
             DI820703. Unpublished study prepared by Miles Inc. 3 9 p.

42585801     Fontaine, L. (1992) Product Chemistry of Di-Syston: Lab Project Number:
             102590: 103869: 103870.  Unpublished study prepared by Miles, Inc. 85 p.
                                       ,  153

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42585802    Schmidt, J.; Anderson, T.; Dyer, D. (1992) Laboratory Volatility of Disulfoton
             from Soil: Lab Project Number: 40259: DI152101: 103907. Unpublished study
             prepared by ABC Laboratories, Inc.  70 p.

42585803    Stafford, T. (1992) Technical Dl-Syston: An Acute Oral LD50 with Bobwhite
             Quail: Lab Project Number: DI711701: 103911. Unpublished study prepared by
             Miles Inc. 33 p.

42629000    Miles, Inc. (1993) Submission  of toxicity data in support of FIFRA 6(a)(2)
             requirements/data call-in for Disyston Technical. Transmittal of 1 study.

42629001    Lintott, D. (1993) Disyston Technical:  Toxicity to Embryos and Larvae of the
             Sheepshead Minnow (Cyprinodon variegatus) under Flow-through Test
             Conditions: Lab Project Number: J9202001: 105001. Unpublished study prepared
             by Toxikon Environmental Sciences. 78 p.

42755800    Miles Inc. (1993) Submission of toxicity data in support of the data call-in notice
             for disulfoton. Transmittal of 1 study.

42755801    Sheets, L.; Lake, S. (1993) An Acute Oral Neurotoxicity Screening Study with
             Technical Grade Disulfoton (Dl-Syston)  in Rats: Lab Project Number: 92-412-OB:
             103992.  Unpublished study prepared by Miles Inc.  400 p.

42808900    Miles Agriculture Division (1993) Submission of metabolism data in response to
             Data Call-in notice for DI-SYSTON (Disulfoton). Transmittal of 1 study.

42808901    Lee, S.; Hanna, L.; Johnston, K. et al. (1985) Excretion and Metabolism of
             DI-SYSTON in Rats: Lab Project Number: 90946. Unpublished study prepared by
             MobayCorp. 67 p.

42850200    Miles Inc. (1993) Submission of residue data in support of the Data Call-In for
             disulfoton. Transmittal of 1 study.

42850201    Mathew, A.; Sloan, N. (1993) Residues in Mature Green Tobacco Leaves: (carbon
             14) Disulfoton: Lab Project Number: DI171601: 105170. Unpublished study
             prepared by Miles Inc. 38 p.

42977400    Miles Inc. (1993) Submission of Toxicity Data for DI-SYSTON (disulfoton) in
             Support of Data Call-in Reregistration. Transmittal of 1 Study.

42977401    Sheets, L. (1993) A Subchronic Dietary Neurotoxicity Screening Study with
             Technical Grade Disulfoton (DI-SYSTON) in Fischer 344 Rats: Lab Project
             Number: 92-472-NS. Unpublished study prepared by Miles Inc., Agriculture
             Division.  471 p.
                                          154

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43032501    Hancock, G. (1993) Effect of Technical DI-SYSTON on Bobwhite Quail
             Reproduction: Lab Project Number: 106227: DI741701. Unpublished study
             prepared by Miles, Inc. 130 p.

43032502    Hancock, G. (1993) Effect of Technical DI-SYSTON on Mallard Duck
             Reproduction: Lab Project Number: 106228: DI740801. Unpublished study
             prepared by Miles, Inc. 126 p,

43042500    Miles, Inc. (1993) Submission of Environmental Fate and Toxicology Data in
             Support of Disulfoton Data Call-in. Transmittal of 3 Studies.

43042501    Graney, R. (1989) Supplemental Submission Containing Raw Data for: Uptake,
             Depuration and Bioconcentration of (carbon 14) DI-SYSTON to Bluegill Sunfish
             (Lepomis macrochirus): Lab Project Number: 95078-1: 035818: 95078.
             Unpublished study prepared by Analytical Biochemistry Labs, Inc. 17 p.

43042502    Grace, T.; Cain, K.; Delk, J. (1990) Dissipation of Disulfoton in California Soils:
             Lab Project Number: 100158: DI830089R01: ML022101. Unpublished study
             prepared by Plant Sciences, Inc.; Siemer and Associates, Inc.; and PTRL-West.
             1795 p.

43042503    Kasper, A.; Shadrick, B.; Cain, K.; et al. (1992) Anaerobic Aquatic Metabolism of
             (carbon  14)-Disulfoton: Lab Project Number: 103945: DI042401.  Unpublished
             study prepared by Miles, Inc. 3 8 p.

43058400    Miles Agriculture Division (1993) Submission of special subchronic toxicity data
             in response to DCI for registration standard for DI-SYSTON (disulfoton).
             Transmittal of 1 study.

43058401    Christenson, W.; Wahle, B. (1993) Technical Grade Disulfoton (DI-SYSTON): A
             Special 6-Month Feeding Study to Determine a Cholinesterase No Observed Effect
             Level in the Rat: Lab Project Number: 91/972/IR: 106336. Unpublished study
             prepared by Miles Inc. Agriculture Division Toxicology. 323 p.

43058600    Miles Inc. (1993) Submission of Product Chemistry Data for DI-SYSTON in
             Support of Data Call-in. Transmittal of 6 Studies.

43058601    Fontaine, L. (1993) Product Chemistry of DI-SYSTON Technical: Supplement to
             MRID 00150088: Lab Project Number: MCL0412: 011054:  101010. Unpublished
             study prepared by Miles Inc., Agriculture Division. 54 p.

43058602    Fontaine, L. (1993) Product Chemistry of DI-SYSTON Technical: Supplement to
             MRID 00150088: Lab Project Number: 86255:  106454: C-4.54. Unpublished
             study prepared by Miles Inc., Agriculture Division. 37 p.
                                         155

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43058603     Fontaine, L. (1993) Product Chemistry of DI-SYSTON 68% Concentrate:
             Supplement to MRJD 00148493 and 00150088: Lab Project Number: 501835:
             PC0533: BR 1862. Unpublished study prepared by Miles Inc., Agriculture
             Division.  19 p.

43058604     Fontaine, L. (1993) Product Chemistry of DI-SYSTON 68% Concentrate:
             Supplement to MRID 00148492 and 00150088: Lab Project Number: 86767: BR
             1863: PC0539. Unpublished study prepared by Miles Inc., Agriculture Division.
             12 p.

43058605     Fontaine, L. (1993) Product Chemistry of DI-SYSTON 2% Granular for
             Repackaging Use Only: Supplement to MRID 00148492 and 00150088: Lab
             Project Number: 401630: 301422: 301476. Unpublished study prepared by Miles
             Inc., Agriculture Division. 33 p.

43058606     Fontaine, L. (1993) Product Chemistry of DI-SYSTON 2% Granular for
             Repackaging Only: Supplement to MRID 00148493 and 00150088: Lab Project
             Number: 86766: PC0536: BR 1865. Unpublished study prepared by Miles Lac.,
             Agriculture Division. 12 p.

43060100     Miles Inc. (1993) Submission of Environmental Fate Data for DI-SYSTON in
             Support of Data Call-in Reregistration. Transmittal of 1 Study.

43060101     Hanlon, C.; Cain, K. (1987) Identification of Residues from Bluegill Sunfish
             Exposed to (carbon-14)-DI-SYSTON: Lab Project Number: DI-03-A: 95076.
             Unpublished study prepared by Mobay Corp., Agricultural Chemicals Div. 26 p.

43093600     Miles Inc. (1994) Submission of Product Chemistry Data for Disulfoton
             (DI-SYSTON) in Support of a Data Call-In Notice for Registration Standard.
             Transmittal of 1 Study.

43093601     Fontaine, L. (1993) Product Chemistry of DI-SYSTON Technical: Supplement to
             MRED 00148493 and 00150088: Lab Project Number: 91267: 95065: 95066,
             Unpublished study prepared by Miles Inc., Agriculture Division. 102 p.

43222402     Fought, L.; Smith, D.; King, L. (1994) Metabolism of Disulfoton in Soybeans: Lab
             Project Number: DI041603: 106414. Unpublished study prepared by Miles Inc.
             163 p.

43222403     Fought, L.; Smith, D.; King, L. (1994) Metabolism of Disulfoton in Lettuce:  Lab
             Project Number: DI041601: 106415. Unpublished study prepared by Miles lac.
             117 p.
                                        156

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43222404    Fought, L.; Smith, D.; King, L. (1994) Metabolism of Disulfoton in Potatoes: Lab
             Project Number: DI041602: 106416. Unpublished study prepared by Miles Inc.
             117 p.

43231600    Miles Agriculture Division (1994) Submittal of Volatility Data in Support of
             Reregistration of DI-SYSTON. Transmittal of 1 study.

43231601    Schmidt, J.; Anderson, T.; Dyer, D. (1994) Laboratory Volatility of Disulfoton
             from Soil: Amended Final Report #40259: Lab Project Number: DI152101:
             106441: 40259. Unpublished study prepared by ABC Laboratories, Inc. 70 p.

43360200    Miles, Inc. (1994)  Submission of Toxicity Data in Support of Disulfoton
             Registration Standard. Transmittal of 1 Study.

43360201    Warren, D. (1994) Dermal Absorption of (carbon 14)-Disulfoton from the
             Disystbn 8 Formulation (in Rats): Lab Project Number: 94-722-YP: 106368.
             Unpublished study prepared by Miles, Inc. 64 p.

43447700    Miles, Inc. (1994)  Submission of Environmental Fate and Residue Data in Support
             of Disulfoton Registration Standard. Transmittal of 5 Studies.

43447701    Pither, K.; Stevenson, T. (1989) Residues of (carbon 14) DI-SYSTON in
             Rotational Crops: Lab Project Numbers 94354: 94354-1.  Unpublished study
             prepared by Mobay Corp. 32 p.

43447702    Minor, R.; Stevenson, T. (1994) Residues of (carbon 14) DI-SYSTON in
             Rotational Crops: Addendum 2: Additional Data and Replies to EPA Review: Lab
             Project Number: 94354-2. Unpublished study prepared by Miles, Inc.  32 p.

43447703    Delk, J.; Johnson, T.; Olson, T. (1988) Field Rotational Crops: Residues of
             DI-SYSTON and its Metabolites: Lab Project Numbers: 8500: 94356-1: 21319.
             Unpublished study prepared by Mobay Corp.; Analytical Development Corp.; and
             Chemonics Labs, Inc. 416 p.

43447704    Minor, R. (1994) Field Rotational Crops: Residues of DI-SYSTON and its
             Metabolites: Addendum 2: Additional Data and Replies to EPA Review: Lab
             Project Numbers: 94356-2: STF-DI038-86R: STF-DI050-86R. Unpublished study
             prepared by Miles, Inc.; Analytical Development Corp.; and Chemonics Labs, Inc.
             203 p.

43447705    Wiedmann, J.; Koch, D. (1994) Freezer Storage Stability of Disulfoton and
             Metabolites in Crops and Crop Processed Commodities: Lab Project Numbers:
             106214: 92-0050: 5203-92-0050-CR-001. Unpublished study prepared by
             Ricerca, Inc.  746 p.
                                         157

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43512200    Miles, Inc. (1995) Submission of Metabolism Data in Support of the Disulfbton
             Registration Standard. Transmittal of 1 Study.

43512201    Lin, H.; Green, D.(1994) Anaerobic Aquatic Metabolism of (carbon
             14)-Disulfoton: (Identification and Characterization of the Minor Metabolites):
             (Addendum): Lab Project Numbers: DI042401: 103945-1. Unpublished study
             prepared by Miles, Inc. 51 p.

43568500    Miles, Inc. (1995) Submission of Aquatic Microcosm Data in Support of FIFRA
             6(a)(2) for Di-Syston Technical. Transmittal of 1 Study.

43568501    Cook, R.; Kennedy, J. (1994) Assessment of the Potential Ecological and
             Biological Effects of DI-SYSTON on Aquatic Ecosystems as Measured in a
             Concrete Tank System: Lab Project Number: 106902. Unpublished study prepared
             by University of North Texas. 434 p.

43610900    Bayer Corp. (1995) Submission of Hazard to Aquatic Organisms Data in Support
             of FIFRA 6(a)(2) for Di-Syston. Transmittal of 1 Study.

43610901    Davis, J. (1995) Chronic Toxicity of DISYSTON to the Mysid Shrimp
             (Mysidopsis bahia) Under Flow-Through Conditions: Lab Project Number:
             106924: J9408005: J9203005A.  Unpublished study prepared by Toxikon
             Environmental Sciences. 84 p.

43615700    Bayer Corp. (1995) Submission of toxicity data in support of registration standard
             for disulfoton. Transmittal of 1  study.

43615701    Herbold, B. (1995) S 276: Micronucleus Test on the Mouse: Lab Project Number:
             23887: T/2059008: S/276.  Unpublished study prepared by Bayer AG.  51 p.

43738000    Bayer Corp. (1995) Submission of Hazard to Aquatic Organisms Data in Support
             of FIFRA 6(a)(2) for Di-Syston (Sulfone and Sulfoxide). Transmittal of 2 Studies.

43738001    Bowers, L. (1995)  Chronic Toxicity of (carbon 14)-Di-Syston Sulfone to the
             Waterflea (Daphnia magna) Under Flow-Through Conditions: Lab Project
             Number: 106946: DI840701. Unpublished study prepared by Bayer Corp. 49 p.

43738002    Bowers, L. (1995)  Chronic Toxicity of (carbon 14)-Di-Syston Sulfoxide to the
             Waterflea (Daphnia magna) Under Flow-Through Conditions: Lab Project
             Number: 106947: DI840702. Unpublished study prepared by Bayer Corp. 49 p.

43800100    Bayer Corp. (1995) Submission of Environmental Fate Data in Support of the
             Disulfoton Registration Standard. Transmittal of 1 Study.
                                         158

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43800101     Blumhorst, M.; Yen, P. (1995) Aerobic Soil Metabolism of (Ethylene-1-(carbon
             14))-Disulfoton: Lab Project Number: 106944: 122S20: DI042103. Unpublished
             study prepared by EPL Bio-Analytical Labs, Inc. and Bayer Corp. 113 p.

43881100     Bayer Corp. (1995) Submission of Environmental Fate and Residue Data in
             Support of the Registration Standard for Disulfoton. Transmittal of 1 Study.

43881101     Erhardt-Zabik, S.; Ewing, A.; Johnson, T. et al. (1989) Validation of Mobay
             Method No. 94328--A Method for the Determination of DI-SYSTON and its
             Sulfoxide and Sulfone Metabolites in Soil: Lab Project Number: 99117: 146W.
             Unpublished study prepared by Pharmacology & Toxicology Research
             Laboratory-West. 43 p.

43957300     Bayer Corp. (1996) Submission of Residue Chemistry Data in Support of the
             Registration Standard for Disulfoton. Transmittal of 1 Study.

43957301     Lemke, V. (1996) Freezer Storage Stability of Disulfoton and Metabolites in Crops
             and Crop Processed Commodities: Data for 36 Months: Addendum 1: Lab Project
             Number: 5203-92-0050-CR-002: DI131601: 106214-1. Unpublished study
             prepared by Ricerca, Inc. 479 p.

43960500     Bayer Corp. (1996) Submission of Hazard to Wildlife and Aquatic Organisms
             Data in Support of FIFRA 6(a)(2) for Disulfoton. Transmittal of 1 Study.

43960501     Dionne, E. (1996) Di-Syston-The Chronic Toxicity to the Sheepshead Minnow
             (Cyprinodon variegatus) During a Full-Life Cycle Exposure: Lab Project Number:
             13507.0894.6110.592: 107119: DI852801. Unpublished study prepared by
             Springborn Labs, Inc. 527 p.

44146500     Bayer Corp. (1996) Submission of Metabolism Data in Support of the Registration
             Standard for Disulfoton. Transmittal of 3 Studies.

44146501     Hall, L.; Hartz, A. (1996) The Metabolism of Disulfoton in Soybeans: Addendum
             1: Additional Metabolite Identification: Lab Project Number: 106414-1:
             DI041605. Unpublished study prepared by Bayer Corp. 88 p.

44146502     Hall, L.; Hartz, A. (1996) The Metabolism of Disulfoton in Potatoes: Addendum 1:
             Additional Metabolite Identification: Lab Project Number: DI041606: 106416-1.
             Unpublished study prepared by Bayer Corp. 89 p.

44146503     Schepers, G. (1996) Recovery of Disulfoton and its Metabolites in Tobacco Smoke
             of Cigarettes Made from Tobacco Grown in Disulfoton-Treated Soil: Lab Project
             Number: DI171602: 107375:0197/1816.  Unpublished study prepared by INBIFO,
             Institue Fuer Biologische Forschung and Bayer Corp. 228 p.
                                         159

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44248001    Minor, R. (1997) Disulfoton: Replies to EPA's Review of Data Submitted in
             Response to the Data Call-in: (Nature and Magnitude of Residues in Plants): Lab
             Project Number: 107145. Unpublished study prepared by Bayer Corp. 110 p.

44248002    Jones, R.; Hastings, T. (1997) Technical Grade Disulfoton: A Chronic Toxicity
             Feeding Study in the Beagle Dog: Lab Project Number: 107499: 8097: 94-276-XZ.
             Unpublished study prepared by Bayer Corp. 991 p.

44248003    Duah, F. (1997) Di-Syston 8—Magnitude of the Residue in Head Lettuce and Leaf
             Lettuce: (Final Report): Lab Project Number: 107520: DI19LH01: DI19LL01.
             Unpublished study prepared by Bayer Corp. 163 p.

44248004    Lenz, C. (1997) Freezer Storage Stability of Disulfoton and Metabolites in Potato
             Processed Commodities: (Final Report): Lab Project Number: 107523: DI131601:
             5203-92-0050-CR-003. Unpublished study prepared by Ricerca, Inc.  485 p.

44248005    Harbin, A. (1996) Residues of Di-Syston in Field-Treated Potatoes and Processed
             Commodities: (Final Report): Lab Project Number: 107525: DI19PO01: PR94312.
             Unpublished study prepared by Bayer Corp. and The National Food Lab, Inc. 226
             P-

44248006    Freeseman, P. (1997) Di-Syston 8~Magnitude of the Residue in Cotton Processed
             Commodities: (Final Report): Lab Project Number: 107541: DI19CT03: PR95331.
             Unpublished study prepared by Bayer Corp. and Texas A&M University.  300 p.

44248007    Harbin, A. (1997) Di-Syston 15G and 8--Magnitude of the Residue in Sorghum
             Aspirated Grain Fractions: (Final Report): Lab Project Number: 107656:
             DI19SO01: PR95329. Unpublished study prepared by Bayer Corp. and Texas
             A&M University.  176 p.

44248008    Duah, F. (1997) Di-Syston ISO-Magnitude of the Residue in Coffee Processed
             Commodities: (Final Report): Lab Project Number: 107657: DI19CF01: PR94330.
             Unpublished study prepared by Bayer Corp. and The National Food Lab, Inc. 233.
             P-

44248009    Harbin, A. (1997) Di-Syston 8—Magnitude of the Residue in Corn Aspirated Grain
             Fractions and Processed Commodities: (Final Report): Lab Project Number:
             107691: DI19CO01: STF-DI001-96P. Unpublished study prepared by Bayer Corp.
             and Texas A&M University. 706 p.

44248010    Harbin, A. (1997) Di-Syston 15G and 8--Magnitude of the Residue in Wheat
             Aspirated Grain Fractions and Processed Commodities: (Final Report): Lab
             Project Number: 107692: DI19WH02:  PR95330. Unpublished study prepared by
             Bayer Corp. and Texas A&M University. 459 p.
                                         160

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44301900    Bayer Corp. (1997) Submission of Residue Data in Support of the Di-Syston
             (Disulfoton) Registration Standard. Transmittal of 1 Study.

44301901    Schepers, G. (1997) Recovery of Disulfoton and Its Metabolites in Tobacco
             Smoke of Cigarettes Made from Tobacco Grown in Disulfoton-Treated Soil:
             Addendum 1: Response to EPA Requests and Inquiries: Lab Project Number: P
             0197/1816: 107375-1: 107375.  Unpublished study prepared by INBIFO Institut
             fuer Biologische Forschung GmbH. 23 p.

44342100    Bayer Corp. (1997) Submission of Metabolism Data in Support of the Disulfoton
             Registration Standard. Transmittal of 1 Study.

44342101    Krolski, M.; Hall, L. (1997) Metabolism of Disulfoton in Crops: Replies to
             Comments and Questions from the EPA: Lab Project Number: 107834.
             Unpublished study prepared by  Bayer Corp. 24 p. {OPPTS 860.1300}

44369901    Lam, C.; Bowers, L. (1997) Acute Toxicity of Disulfoton Sulfone to the
             Sheepshead minnow (Cyprinodon variegatus) Under Static Conditions: Lab
             Project Number: DI832801: 107828. Unpublished study prepared by Bayer Corp.
             32 p

44369902    Lam, C.; Bowers, L. (1997) Acute Toxicity of Disulfoton Sulfoxide to the
             Sheepshead minnow (Cyprinodon variegatus) Under Static Conditions: Lab
             Project Number: DI832802: 107829. Unpublished study prepared by Bayer Corp.
             33 p.

44373102    Dobbs, M. (1997) Aquatic Effects Summary and Risk Assessment for Disulfoton:
             Lab Project Number: 107846. Unpublished study prepared by Bayer Corp.  34 p.

44373103    Leimkuehler, W.; Valadez, S. (1989) Soil Adsorption and Desorption of (carbon
             14) Di-Syston: Lab Project Number: 99721: DI182101.  Unpublished study
             prepared by Mobay Corp. 39 p.

44440800    Bayer Corp. (1997) Submission of Toxicology Data in Support of the FIFRA
             6(a)(2) Requirement for Di-Syston Technical. Transmittal of 1 Study.

44440801    Astroff, A. (1997) A Two Generation Reproductive Toxicity Study with
             Disulfoton Technical (DISYSTON) in the Sprague-Dawley Rat: Lab Project
             Number: 108002: 8368: 95-672-FZ. Unpublished  study prepared by Bayer Corp.
             1339p.

44688001    Willard, T. (1998) Dissipation of Dislodgeable Foliar Disulfoton Residues from
             Di-Syston 8 Treated Potatoes: Final Study Report: Lab Project Number:
             AA970771: 108561: TM E-3. 00-01. Unpublished study prepared by American
             Agricultural Services, Inc. 168  p.  {OPPTS 875.2100}
                                         161

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44821700    Bayer Corporation (1999) Submission of Risk Assessment and Exposure Data in
             Support of the Registration of Disulfoton. Transmittal of 2 Studies.

44821701    Fix, L. (1999) Disulfoton: A Chronic Dietary Exposure Analysis and Risk
             Assessment for Bayer Support Uses: Lab Project Number: 108784. Unpublished
             study prepared by Bayer Corporation. 203 p.

44821702    Fix, L. (1999) Disulfoton: An Acute Dietary Exposure Analysis and Risk
             Assessment for Bayer Support Uses: Lab Project Number: 108785. Unpublished
             study prepared by Bayer Corporation. 264 p.

44834000    Bayer Corporation (1999) Submission of Residue Chemistry Data in Support of
             the Reregistration of Disulfoton.  Transmittal of 3 Studies.

44834001    Thomburg, W. (1959) Di-Syston, Dylox, Systox, and Guthion: Thermal
             Destruction During Processing of Spinach, Apricots, and Tomato Leaves: Lab
             Project Number: 4882. Unpublished study prepared by California Packing
             Corporation.  37 p.

44870601    Polakoff, B.; Daniel, A.; Osborn, D. et al. (1999) Interim Report:
             Organophosphates Market Basket Survey: Lab Project Number: OPMBS-01:
             98-02:. Unpublished study prepared by Novigen Sciences, Inc.  333 p.

44904400    Bayer Corporation (1999) Submission of Product Chemistry Data in Support of the
             Registration of Di-Syston Technical Insecticide, Di-Syston 2% Granular Systemic
             Insecticide, and Di-Syston 68% Concentrate.  Transmittal of 3 Studies.

44904401    Fontaine, L. (1999) Product Chemistry of Di-Syston Technical: Lab Project
             Number: 109183: 109184: ANR-03900. Unpublished study prepared by Bayer
             Corporation.  809 p. {OPPTS 830.1550, 830.1600, 830.1620, 830.1700, 830.1750,
             830.7050}

44904403    Fontaine, L. (1999) Product Chemistry of Di-Syston 68% Concentrate: Lab Project
             Number: ANR-03899: C-4.54: BR2013. Unpublished study prepared by Bayer
             Corporation.  30 p. {OPPTS  830.1800}

44972201    Merricks, D. L. (1999) Exposure  of Professional Lawn Care Workers During the
             Mixing, Loading, and Application of Granular Turf Pesticides Utilizing a
             Surrogate Compound. Unpublished study prepared by Agrisearch Inc.(Frederick,
             MD) and Ricera Inc. (Painesville, OH)

44996401    Andrews, P.; Popp, A. (1999) Study for Delayed Neurotoxicity Following Acute
             Oral Administration to Hens: Disulfoton: Lab Project Number: PH-29253: T
             2068512: 9098. Unpublished study prepared by Bayer AG. 75 p.
                                         162

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45239601     Flucke, W. (1988) S 276 Technical (Common Name: Disulfoton, The Active
             Ingredient of DI-SYSTON): Study of Subacute Dermal Toxicity to Rabbits: Lab
             Project Number: 98347: 88-T-126:16342.  Unpublished study prepared by Bayer
             AG.  154 p.

 45239602    Croutch, C.; Sheets, L. (2000) Repeated-Exposure (3-Day) Dermal Toxicity Study
             with 1% G Di-Syston in Rats: Lab Project Number: 00-S22-BS: 109956.
             Unpublished study prepared by Bayer Corporation.  40 p.

45250702     Pontal. P.G. (2001) Worker Exposure Study During Application of Regent 20GR
             in Banana Plantation, (RP Study 94/136).  Rhone-Poulenc Agrochimie

45333400     Bayer Corporation (2001) Submission of Risk Assessment and Exposure Data in
             Support of the Registration of Disulfoton 1% G. Transmittal of 2 Studies.

45333401     Merricks, L. (2001) Determination of Dermal (Hand and Forearm) and Inhalation
             Exposure to Disulfoton Resulting from Residential Application of Bayer
             Advanced Garden 2-in-l Systematic Rose and Flower Care to Shrubs and Flower
             Beds: Lab Project Number: 4201.  Unpublished study prepared by Agrisearch Inc.
             178 p.
                                        163

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164

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                                   Appendix E

                            GENERIC DATA CALL-IN

       See the following table for a list of generic data requirements. Note that a complete Data
Call-In (DCI), with all pertinent instructions, is being sent to registrants under separate cover.
                                         165

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                                   Appendix F
                    PRODUCT SPECIFIC DATA CALL IN

       See attached table for a list of product-specific data requirements. Note that a complete
Data Call-IN (DCI), with all pertinent instructions, is being sent to registrants under a separate
cover.
                                        171

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                                     APPENDIX G

   EPA'S BATCHING OF DISULFOTON PRODUCTS FOR MEETING ACUTE TOXICITY
                    DATA REQUIREMENTS FOR REREGISTRATION

        In an effort to reduce the time, resources and number of animals needed to fulfill the
acute toxicity data requirements for reregistration of products containing disulfoton as the
primary active ingredient, the Agency has batched products which can be considered similar for
purposes of acute toxicity. Factors considered in the sorting process include each product's active
and inert ingredients (identity, percent composition and biological activity), type of formulation
(e.g., emulsifiable concentrate, aerosol, wettable powder, granular, etc.), and labeling (e.g., signal
word, use classification, precautionary labeling, etc.).  Note: the Agency is not describing
batched products as "substantially similar" since some products with in a batch may not be
considered chemically similar or have identical use patterns.

        Using available information, batching has been accomplished by the process described hi
the preceding paragraph. Notwithstanding the batching process, the Agency reserves the right to
require, at any time, acute toxicity data for an individual product should need arise.

        Registrants of products within a batch may choose to cooperatively generate, submit or
cite a single battery of six acute toxicological studies to represent all the products within that
batch. It is the registrants' option to participate in the process with all other registrants, only
some of the other registrants, or only their own products within in a batch, or to generate all the
required acute toxicological studies for each of their own products.  If the registrant chooses to
generate the data for a batch, he/she must use one of the products  within the batch as the test
material.  If the registrant chooses to rely upon previously submitted acute toxicity data, he/she
may do so provided that the data base is complete and valid by to-days standards (see acceptance
criteria attached), the formulation tested is considered by EPA to be similar for acute toxicity, and
the formulation has not been significantly altered since submission and acceptance of the acute
toxicity data.  Regardless of whether new data is generated or existing data is referenced, the
registrants must clearly identify the test material by EPA Registration Number. If more than one
confidential statement of formula (CSF) exists for a product, the registrant must indicate the
formulation actually tested by identifying the corresponding CSF.

        In deciding how to meet the product specific data requirements, registrants must follow
the directions given in the Data Call-In Notice and its attachments appended to the IRED.  The
DCI Notice contains two response forms which are to be completed and submitted to the Agency
within 90 days of receipt. The first form, "Data Call-in Response," asks whether the registrant
will meet the data requirements for each product. The second form, "Requirements Status and
Registrant's Response," lists the product specific data required for each product, including the
standard six acute toxicity tests. A registrant who wishes to participate in a batch must decide
whether he/she will provide the data or depend on someone else to do so.  If the registrant
supplies the data to support a batch of products, he/she must select the one of the following
options: Developing data (Option 1), Submitting an existing Study (Option 4), Upgrading an
existing Study (Option 5), or Citing an Existing Study (Option ). If a registrant depends on

                                          177

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another's data, he/she must choose among: Cost sharing (Option 2), Offers to Cost Share (Option
3) or Citing an Existing Study (Option 6). If a registrant does not want to participate in a batch,
the choices are Options 1,4, 5 or 6. However, a registrant should know that choosing not to
participate in a batch does not preclude other registrants in the batch from citing his/her studies
and offering to cost share (Option 3) those studies.

        Fifty eight products were found which contain disulfoton as the active ingredient. These
products have been placed into four batches and a "No batch" in accordance with the active and
inert ingredients and type of formulation.
Batch 1
EPA Reg. No.
3125-173
3125-183
Percent active ingredient
95.0
98.5
Formulation Type
Liquid
Liquid
Batch 2
EPA Reg. No.
70-236
3125-172
34704-586
Percent active ingredient
15.0
15.0
15.0
Formulation Type
Solid
Solid
Solid
Batch 3
EPA Reg. No.
192-74
192-119
11474-70
Percent active ingredient
2.0
2.0
2.0
Formulation Type
Solid
Solid
Solid
                                           178

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Batch 3a*
EPA Reg. No.
4-153
869-223
3125-83
3125-116
7401-26
7401-323
28293-277
33955-490
Percent active ingredient
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
Formulation Type
Solid
Solid
Solid
Solid
Solid
Solid
Solid
Solid
*Batch 3a acute data may be cited to support Batch 3  products.
Batch 4
EPA Reg. No.
192-126
192-164
239-2134
572-346
769-908
802-426
869-76
3125-152
3125-517
5887-61
5887-171
8660-191
9688-94
33955-489
34704-785
42057-51
49585-28
Percent active ingredient
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
Formulation Type
Solid
Solid
Solid
Solid
Solid
Solid
Solid
Solid
Solid
Solid
Solid
Solid
Solid
Solid
Solid
Solid
Solid
                                            179

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Batch 4af
EPA Reg. No.
4-253
4-420
16-171
769-850
7401-235
9404-3
46260-2
46260-12
46260-35
59144-23
Percent active ingredient
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
Formulation Type
Solid
Solid
Solid
Solid
Solid
Solid
Solid
Solid
Solid
Solid
fBatch 4a acute data may be cited to support for Batch 4 products,
No Batch
EPA Reg. No.
264-459
264-464
400-408
400-411
400-475
2935-362
5481-415
8660-125
7401-4
3125-158
3125-307
32802-32
34704-287
34704-475
46260-36
Percent active ingredient(s)
Ethoprop - 10.0
Disulfoton - 5.0
Ethoprop- 46.0
Disulfoton - 23.0
PCNB - 6.50
Terrazole- 1.63
Disulfoton - 6.50
PCNB - 6.50
Disulfoton- 6.50
PCNB - 17.5
Terrazole- 4.3
Disulfoton- 17.5
PCNB - 6.5
Disulfoton - 6.5
PCNB - 6.5
Disulfoton - 6.5
Disulfoton- 0.37
Disulfoton - 0.99
Disulfoton- 68.0
Disulfoton - 85.0
Disulfoton - 0.5
PCNB - 6.5
Disulfoton - 6.5
Disulfoton - 0.625
Disulfoton- 2.0
Formulation Type
Solid
Solid
Solid
Solid
Liquid
Solid
Solid
Solid
Solid
Liquid
Liquid
Solid
Solid
Solid
Solid
                                              180

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        APPENDIX H
LIST OF REGISTRANTS SENT DCI
            181

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                                    Appendix I

             LIST OF ELECTRONICALLY AVAILABLE FORMS

Pesticide Registration Forms are available at the following EPA internet site:

             http ://www.epa. gov/opprdOO 1 /forms/

Pesticide Registration. Forms (These forms are in PDF format and require the Acrobat reader)

Instructions

        1.    Print out and complete the forms. (Note: Form numbers that are bolded can be
             filled out on your computer then printed.)

        2.    The completed form(s) should be submitted in hardcopy in accord with the
             existing policy.

        3.    Mail the forms, along with any additional documents necessary to comply with
             EPA regulations covering your request, to the address below for the Document
             Processing Desk.

DO NOT fax or e-mail any form containing 'Confidential Business Information' or 'Sensitive
Information.'

If you have any problems accessing these forms, please contact Nicole Williams at (703)
308-5551orbye-mailatwilliams.nicole@epa.gov.

The following Agency Pesticide Registration Forms are currently available via the internet:
at the following locations:
8570-1
8570-4
8570-5
8570-17
8570-25
8570-27
8570-28
8570-30
Application for Pesticide
Registration/ Amendment
Confidential Statement of Formula
Notice of Supplemental Registration of
Distribution of a Registered Pesticide Product
Application for an Experimental Use Permit
Application for/Notification of State
Registration, of a Pesticide To Meet a Special
Local Need
Formulator's Exemption Statement
Certification of Compliance with Data Gap
Procedures
Pesticide Registration Maintenance Fee Filing.
http://www.ena.gov/oD0rd001/forms/8570-l.pdf

httD.Y/www.eDa.2OV/ODDrd001/forms/8570-4.Ddf
http://www.eDa.eov/ODtird001/forms/8570-5.pdf

htto://www.eDa.gov/ODr>rd001/forms/8570-17.Ddf
htto://w\vw.epa.eov/ODordOO l/forms/8570-25.Ddf

htto://www.epa.eov/opprd001/forms/8570-27.pdf
http://www.eua.gov/opprd001/forms/8570-28.odf

htto://www.epa. eov/opordOO 1 /forms/8570-30.pdf
                                          183

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8570-32
8570-34
8570-35
8570-36
8570-37
Certification of Attempt to Enter into an
Agreement with other Registrants for
Development of Data
Certification with Respect to Citations of Data
(PR Notice 98-5)
Data Matrix (PR Notice 98-5)
Summary of the Physical/Chemical Properties
(PR Notice 98-1)
Self-Certification Statement for the
Physical/Chemical Properties (PR Notice
98-1)
htto://www.eDa.20v/or)Drd001/forms/8570-32.pdf

http://www.eDa.sov/opppmsdl/PR Notices/pr98-5.pdf

http://www.epa.eov/ODpmnsdl/PR Notices/rjr98-5.pdf
httD://www.eDa.eov/opt>pmsdl/PR Notices/Dr98-l.pdf

httD://www.eDa.gov/ODDpmsdl/PR Notices/pr98-l .pdf

184

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Pesticide Registration Kit
www.epa.gov/pesticldes/registrationkit/
Dear Registrant:

       For your convenience, we have assembled an online registration kit which contains the
following pertinent forms and information needed to register a pesticide product with the U.S.
Environmental Protection Agency's Office of Pesticide Programs (OPP):


1.      The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Federal Food,
       Drug and Cosmetic Act (FFDCA) as Amended by the Food Quality Protection Act (FQPA)
       of 1996.

2.      Pesticide Registration (PR) Notices

       a.    83-3 Label Improvement Program—Storage and Disposal Statements
       b.    84-1 Clarification of Label Improvement Program
       c.    86-5 Standard Format for Data Submitted under FIFRA
       d.    87-1 Label Improvement Program for Pesticides Applied through Irrigation Systems
             (Chemigation)
       e.    87-6 Inert Ingredients in Pesticide Products Policy Statement
       f.     90-1 Inert Ingredients in Pesticide Products; Revised Policy Statement
      , g.    95-2 Notifications, Non-notifications, and Minor Formulation Amendments
       h.    98-1 Self Certification of Product Chemistry Data with Attachments (This document
             is in PDF format and requires the Acrobat reader.)

       Other PR Notices can be found at http://www.epa.gov/opppmsdl/PR_Notices

3.      Pesticide Product Registration Application Forms (These forms are in PDF format and will -
       require the Acrobat reader).

       a.    EPA Form No. 8570-1, Application for Pesticide Registration/Amendment
       b.    EPA Form No. 8570-4, Confidential Statement of Formula
       c.    EPA Form No. 8570-27, Formulator's Exemption Statement
       d.    EPA Form No. 8570-34, Certification with Respect to Citations of Data
       e.    EPA Form No. 8570-35, Data Matrix

4.      General Pesticide Information (Some of these forms are in PDF format and will require the
       Acrobat reader).

       a.    Registration Division Personnel Contact List
       b.    Biopesticides and Pollution Prevention Division (BPPD) Contacts
       c.    Antimicrobials Division Organizational Structure/Contact List
       d.    53 F.R. 15952, Pesticide Registration Procedures; Pesticide Data Requirements (PDF
             format)
       e.    40 CFR Part 156, Labeling Requirements for Pesticides and Devices (PDF format)
       f.     40 CFR Part 158, Data Requirements for Registration (PDF format)
       g.    50 F.R. 48833, Disclosure of Reviews of Pesticide Data (November 27, 1985)
                                          185

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        Before submitting your application for registration, you may wish to consult some
additional sources of information. These include:

1.      The Office of Pesticide Programs' website.

2.      The booklet "General Information on Applying for Registration of Pesticides in the United
        States", PB92-221811, available through the National Technical Information Service
        (NTIS) at the following address:

             National Technical Information Service (NTIS)
             5285 Port Royal Road
             Springfield, VA  22161

             The telephone number for NTIS is (703) 605-6000.

3.      The National Pesticide Information Retrieval System (NPIRS) of Purdue University's
        Center for Environmental and Regulatory Information Systems. This service does charge a
        fee for subscriptions and custom searches. You can contact NPIRS by telephone at (765)
        494-6614 or through their website.

4.      The National Pesticide Information Center (NPIC) can provide information on active
        ingredients, uses, toxicology, and chemistry of pesticides. You can contact NPIC by
        telephone at (800) 858-7378 or through their website: http://npic.orst.edu..

        The Agency will return a notice of receipt of an application for registration or amended
        registration, experimental use permit, or amendment to a petition if the applicant or
        petitioner encloses with his submission a stamped, self-addressed postcard.  The postcard
        must contain the following entries to be completed by OPP:

                   •      Date of receipt;
                   •      EPA identifying number; and
                   •      Product Manager assignment.

        Other identifying information may be included by the applicant to link the acknowledgment
        of receipt to the specific application submitted.  EPA will stamp the date of receipt and
        provide the EPA identifying file symbol or petition number for the new submission. The
        identifying number should be used whenever you contact the Agency concerning an
        application for registration, experimental use permit, or tolerance petition.

        To assist us hi ensuring  that all data you have submitted for the chemical are properly coded
        and assigned to your company, please include a list of all synonyms, common and trade
        names, company experimental codes, and other names which identify the chemical
        (including "blind" codes used when a sample was submitted for testing by commercial or
        academic facilities).  Please provide  a chemical abstract system (CAS) number if one has
       been assigned.
                                           186

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