United States         Prevention, Pesticides    EPA-HQ-OPP-2007-0973
Environmental Protection     and Toxic Substances    May 2008
Agency            (7508P)
vvEPA
          Reregistration
          Eligibility Decision
          for Siduron

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Reregistration Eligibility Decision (RED) for
                    Siduron

                     ListC

                 Case No. 3130
           Approved by:
            Steven Bradbury, Ph.D.
            Director, Special Review and Reregistration Division
           Date:
               ~~i    r

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Table of Contents


I.     Introduction	6

II.    Chemical Overview	7

   A.   Regulatory History	7
   B.   Chemical Identification	8
   C.   Use Profile	9

III.   Summary of Siduron Risk Assessments	10

   A.   Human Health Risk Assessment	10
      1.       Toxicity of Siduron	10
      2.       Selection of Endpoints	12
      3.       Exposure/Risk Pathway	13
   B.   Environmental Risk Assessment	16
      1.       Environmental Fate and Transport	16
      2.       Ecological Exposure and Risk	17
   B.   Aquatic Organisms	19

IV.   Risk Management and Reregistration Decision	23

   A.   Determination of Reregistration Eligibility	23
   B.   Requirements for Reregistration	23
      1.       Required Data	23
      2        Risk Mitigation	23
   C.   Regulatory Rationale	24
      1.       Human Health and Ecological Risk	24
      3.       Endocrine Screening	25

V    What Registrants Need to Do	26

   A.   Manufacturing Use Products	26
      1.       Additional Generic Data Requirements	26
      2.       Labeling for Technical and Manufacturing Use Products	26
   B.   End-Use Products	26
      1.       Additional Product-Specific Data Requirements	26
      2.       Labeling for End-Use Products	26
   C.   Labeling Changes Summary Table	27

Appendix A. Use Patterns Subject to Reregistration of Siduron (PC Code 035509)	34

Appendix B. Table of Generic Data Requirements and Studies Used to Make the Reregistration Decision	35

Appendix C. Technical Support Documents	38

Appendix D. Citations Considered to be Part of the Data Base Supporting the Reregistration Eligibility Decision. 39

Appendix E. List of Available Related Documents and Electronically Available Forms	47

Pesticide Registration Kit	48

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EPA Siduron Team

Ecological Fate and Effects Division
Carolyn Hammer
Ibrahim Abdel-Saheb
Dana Spatz

Health Effects Division
Yvonne Barnes
Judy Facey
Alan Nielsen
Deborah Smegal

Registration Division
Jim Tompkins

Special Review and Reregistration Division
Dana Friedman
Tom Myers

Biological Economics and Analysis Division
Jenna Carter
Sunil Ratnayake
Elisa JAim

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Glossary of Terms and Abbreviations

a.i.             Active Ingredient
CFR           Code of Federal Regulations
CSF           Confidential Statement of Formula
DCI           Data Call-In
DER           Data Evaluation Record
ESTAC        Endocrine Disrupter Screening and Testing Advisory Committee
EEC           Estimated Environmental Concentration
EPA           Environmental Protection Agency
ESA           Endangered Species Act
EUP           End-Use Product
FDA           Food and Drug Administration
FIFRA         Federal Insecticide, Fungicide, and Rodenticide Act
FFDCA        Federal Food, Drug, and Cosmetic Act
FQPA          Food Quality Protection Act
GENEEC       Tier I Surface Water Computer Model (Estimated Aquatic Environmental Concentrations)
GRAS          Generally Recognized As Safe
LC50           Median Lethal Concentration. A statistically derived concentration of a substance that can be
               expected to cause death in 50% of test animals. It is 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.  A statistically derived single dose that can be expected to cause death in
               50% of the test animals when administered by the route indicated (oral, dermal, inhalation). It is
               expressed as a weight of substance per unit weight of animal, e.g., mg/kg.
LOG           Level of Concern
LOAEL        Lowest Observed Adverse Effect Level
mg/kg/day      Milligram Per Kilogram Per Day
mg/L           Milligrams Per Liter
MRID          Master Record Identification (number). EPA's system of recording and tracking studies
               submitted.
MUP           Manufacturing-Use Product
N/A           Not Applicable
NOAEL        No Observed Adverse Effect Level
OPP           EPA Office of Pesticide Programs
ppb            Parts per Billion
PPE           Personal Protective Equipment
ppm           Parts per Million
RED           Reregistration Eligibility Decision
REI            Restricted Entry Interval
RQ            Risk Quotient
TGAI          Technical Grade Active Ingredient
UV            Ultraviolet
WP S           Worker Protection Standard

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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 risks 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 or not the pesticide meets the "no unreasonable adverse effects" criterion
of FIFRA.

       This document summarizes EPA's human health and ecological risk assessments and
reregistration eligibility decision (RED) for siduron. The document consists of six sections.
Section I contains the regulatory framework for reregistration; Section II provides an overview
of the chemical and a profile of its use and usage; Section III gives an overview of the human
health and environmental effects risk assessments; Section IV presents the Agency's decision on
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 list related information, supporting documents, and studies evaluated for the
reregistration decision. The risk assessments  for siduron and all other supporting documents are
available in the Office of Pesticide Programs (OPP) public docket at http://www.regulations.gov
under docket number EPA-HQ-OPP-2007-0973.

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II.     Chemical Overview

       A.     Regulatory History

       Siduron was originally registered as a pesticide active ingredient in the United States in
1964, and this registration was transferred from E.I. Dupont de Nemours and Company to
Gowan Company in 1994. Gowan Company holds the registrations for the sole technical grade
and sole manufacturing use products. There are 17 additional products containing siduron as an
active ingredient currently registered with the EPA.

       There is only one active ingredient in Case 3130. No tolerances exist for siduron as
siduron is not registered for use on food or feed crops. Table 1 presents the current active
siduron registrations, and siduron is the only active ingredient in the following products.
Table 1. Supported Registrations of Siduron
Registration #
4-146
4-179
538-60
769-840
961-297
961-309
961-319
7401-241
8378-63
8378-64
8660-23
8660-87
9198-50
9198-65
9198-181
10163-213
10163-214
10163-216
32802-28
Product Name
Crabgrass Preventer & Weed Killer
Crabgrass Preventer & Weed Killer
Scotts Starter Fertilizer with Crabgrass Preventer
Anderson's Proturf Starter Fertil w/ Preemergent WE
Miller Tupersan Granular
Greenfield Modern Trebl
Lebanon Crabgrass Control
Lebanon Spring Seeding Crabgrass Preventer with
Grass Food
Ferti lome Crabgrass Preventer Plus Lawn Food
Shaw's Starter Fertilizer with Crabgrass Control 350
Tupersan
Shaw's Tupersan 470 Granules
Vertagreen Crabgrass Preventer with Tupersan
Vertagreen Fertilizer for Professional Turf with
Tupersan
Anderson's Pre-emergent Crabgrass Killer Plus
Fertilizer
The Andersons Professional Turf Products Crabgrass
Preventer
Andersons Starter Fertilizer with Preemergent Weed
Control
Tupersan Herbicide (Formulation Intermediary)
Siduron Technical
Seed Safe - Turf Care
% Active Ingredient (A.I.)
2.75
7.65
3.1
4.7
2.4
4.6
3.71
2.54
3.5
4.7
6.4
3.71
3.5
4.7
3.1
50
70
98.5
3.71

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       A generic data call-in (DCI) was issued for siduron in 1992, and data requirements
included product chemistry, ecotoxicity, acute toxicity, plant toxicity, and environmental fate
studies. In 1995 a DCI was issued for outdoor, residential-use products requiring data for
products used on residential grass and turf. In 1995, a DCI was issued for products used on
commercial agricultural crops, tree crops and ornamental crops for agricultural reentry data.
       B.
Chemical Identification
       Siduron is a phenylurea herbicide registered for us on annual grassy weeds in newly
seeded or established plantings of cool season grasses. The chemical structure and properties of
siduron are presented in Table 2 and Table 3.
 Table 2, Test Compound Nomenclature- Siduron
 Chemical Structure
 Empirical Formula
 Common Name
                         Siduron
 OPP PC Code
                         035509
 IUPAC name
                         1 -(2-methylcyclohexyl)-3 -phenylurea
 Chemical Abstract Service (CAS) Name
                         jV-(2-methylcyclohexyl)-7V'- phenylurea
 CAS Registry Number
                         1982-49-6
Table 3 . Physiochemical Properties
Parameter
Molecular Weight
Water solubility (25°C )
Melting point/range
pH at 20 °C
Density (25°C)
Solubility (25°C )
Vapor pressure (25°C)
Dissociation constant, pKa (20 °C)
Octanol/water partition coefficient, Log(Kow)
UV/visible absorption spectrum
Value
232.36 g/mol
22.3 ppm
133 -141°C
5.7
1.08 g/mol
22.3
O.OOOSmmHg;
4 x 10'9 Ton-
Does not dissociate
0.431
—
Reference
http://www.ars.usda.gov
MRID41277101
MRID 43587001
USDA ARS Pesticide Properties
Database, May 1995
Material Safety Data Sheet
MRID 41277101
Material Safety Data Sheet
MRID 43587001
http://www.ars.usda.gov
Data Gap

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       C.     Use Profile
Type of Pesticide:

Target Pests:


Mode of Action:



Use Sites:

Formulation Type:

Application Methods:
Application Rates:
Application Timing:
Registrants:
Phenylurea herbicide

Registered for control of annual grasses, annual weeds,
barnyardgrass, bermudagrass, crabgrass, and foxtail.

Exact mode of action for target pests is unknown. It is believed to
inhibit some aspect of cell division. It is a root growth inhibitor,
perhaps acting by mitosis disruption.

Registered for use on golf courses, sod farms, and residential turf.

Granular formulations and wettable powder formulations only.

Granular formulations may be applied using belly grinders, push-
type fertilizer spreaders, and tractor-drawn spreaders. Wettable
powder formulations may be applied via chemigation, groundboom
sprayer, low-pressure handwand sprayer, handgun sprayer and
other hand-operated sprayers. The wettable powder formulation
may also be mixed with seed, fertilizer and mulch and applied with
a hydraulic seeder or hydroseeder. There are no prohibitions
against aerial applications on product labels.

End-use product rates range from 2 to 12 Ibs a.i./A/season, with the
exception of a specialty application for golf course greens
permitting /^ Ib of siduron per 1,000 square feet for band
(perimeter) applications.

Siduron is generally applied between March and May to
established grass, spring-seeded grass, and grass planted the
previous fall. A second treatment, to newly seeded areas, may be
made in the fall. Treatments for bermudagrass encroachment may
run into the summer. Spot treatment to overseeded areas in golf
courses is made at seeding.  The specialty application to golf
course greens is made initially in March or April with subsequent
applications at 4 - 5 week intervals, and the label does not specify
a maximum number of  applications.

The registrant for the sole technical grade and manufacturing use
product is Gowan Company. Gowan Company also holds a
registration for one end-use product. Other than Gowan Company,
there are nine primary formulating registrants.

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III.    Summary of Siduron Risk Assessments

       The purpose of this summary is to assist the reader by identifying the key features and
findings of the EPA's risk assessments, and to help the reader better understand the conclusions
reached in the assessments.  The human health and ecological risk assessments and supporting
documents referenced in Appendix C were used to formulate the regulatory decision for the
pesticidal uses of siduron.

       While the risk assessments and related addenda are not included in this document, they
are available in the OPP Public Docket, docket number EPA-HQ-OPP-2007-0973, and may be
accessed through http://www.regulations.gov/.  Hard copies of these documents may also be
found in the OPP public docket under this same docket number.

       A.      Human Health Risk Assessment
       The human health risk assessment addresses potential exposure and risks from all
registered uses of siduron. Siduron is registered for use on golf courses, sod farms, and for
residential use, thus, occupational handler, residential handler, and post-application exposure
were evaluated in the risk assessment. Siduron is not registered for use on any food
commodities, but due to this chemical's persistence in the environment, the Agency did conduct
a drinking water assessment.  For the complete human health risk assessment, please refer to
Siduron Revised Human Health Risk Assessment, May 2008, which is available in the public
docket.
              1.
Toxicity of Siduron
       The toxicological database is limited but sufficient for the risk assessment of siduron.
Siduron has low toxicity via oral and dermal routes of exposure (Category IV and Category III
respectively), is moderately irritating to the eye (Category III), and is not a dermal sensitizer.
The acute toxicity data submitted for this non-food use pesticide are summarized in Table 4.
Table 4. Acute Toxicity Profile of Siduron
Guideline
Number
870.1100
870.1200
870.1300
870.2400
870.2500
870.2600
Study Type
Acute oral - rat
Acute dermal - rabbit
Acute inhalation - rat
Primary eye irritation - rabbit
Primary dermal irritation - rabbit
Dermal sensitization - guinea pig
MRID(s)
41933402
41933403
41933404
41933405
41933406
43351501
Results
LD50 > 5000mg/kg
LD50 > 2.0 g/kg
LC50 could not be
determined, no mortality
Grade 2 erythema in
animals at 24 hours
Slight erythema at 4
hour evaluation
Not a dermal sensitizer
Toxicity
Category
IV
III
IV
III
IV
NA
                                           10

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       The toxicity database for repeat exposure to siduron includes two dermal toxicity studies
in New Zealand white rabbits. The first study, MRTD 41137201, was conducted in 1989, and
rabbits were dosed with siduron at eleven weeks of age, not at ten weeks as originally suggested
in the preliminary human health risk assessment. Testicular effects were noted by the study
authors and these included decreased testes weights, delayed germinal maturation in the testes,
and atrophy of the epididymides and prostate/proprostate. This 21-day dermal toxicity study was
used to establish the point of departure (PoD) for dermal exposure in the Agency's 2007
preliminary human health risk assessment for the registration eligibility decision on siduron.

       A follow-up study (MRTD 42107101) was conducted in 1991 to assess the  reproducibility
of the testicular effects noted in the 1989 dermal study.  The 1991 21-day dermal toxicity test
was conducted with the same species of rabbit and rabbits were dosed at the same  age (as the
1989 study (11 weeks) as well as upon maturation (20 weeks). No testicular, epididymal,
prostate, or serum testosterone effects were seen at any dose level in either age group.

       As a follow-up to the 1991 21-day dermal toxicity study, a study was conducted in 1993
in order to assess the normal course of testicular maturation in untreated New Zealand white
rabbits (MRID 42627001).  This study demonstrated that the progression of testicular maturation
was highly variable in sexually immature rabbits approaching puberty.  Results of these studies
indicate that the putative testicular effects in the 1989 study appear to be an age-related
phenomenon rather than a chemical-related effect.

       Within the past few months, the Agency has reexamined the pathology data from the
1989, 1991, and  1993 studies. The information presented in the 1991 and 1993 dermal studies
(MRID 42107101 and 42627001) support the contention that effects observed in the 1989 study
were due to the high degree of variability in testicular maturation in immature New Zealand
white rabbits as they approach maturity rather than a chemical-related effect.  Consequently, the
Agency has concluded that the effects and endpoint previously identified for dermal exposure in
the 2007 preliminary siduron human health risk assessment are not relevant for risk assessment
purposes.

       The Agency has also removed the 3x database uncertainty factor applied to the oral and
inhalation risk assessment for the lack of an oral study that evaluated the potential  testicular
effects observed in immature rabbits following repeated dermal exposures since the Agency has
concluded the effects observed in the 1989  study were not a chemical-related phenomenon.
Please see the following document, located in the OPP Public Docket, docket number EPA-HQ-
OPP-2007-0973, for further explanation:

       Siduron: Hazard Characterization and Endpoint Selection Reflecting the Review
       of the Testicular Maturation in Prepubertal New Zealand  White Rabbits Toxicity Study.
       Dated May 1, 2008.

       A metabolism study and carcinogenicity studies are not required for siduron because of
siduron's classification as a non-food use chemical.  It should, however, be  noted that there was
no evidence of mutagenicity in the in vivo and in vitro assays. Acute and subchronic
neurotoxicity studies are not available for siduron; however, there were no clinical signs of any
                                           11

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acute, subchronic, or developmental toxicity in the literature to suggest that siduron elicits a
neurotoxic effect.  The Agency is not requiring additional neurotoxicity studies at this time.

               2.      Selection of Endpoints

       Table 5 summarizes the toxicological doses and endpoints used in the human health risk
assessment of siduron. Uncertainty factors were applied in estimating the reference dose (RfD)
to account for extrapolation from animal to human, potential variation in sensitivity among
members of the human population, and use of a short-term study for long-term risk.
Table 5. Summary of Toxicological Doses and Endpoints for Siduron
Exposure/
Scenario
Acute Dietary
(All Populations)
Chronic Dietary
(All Populations)
Incidental Oral
Short- (1-30 days)
& Intermediate- (1-
6 month) Term
Dermal
Short- (1-30 days)
& Intermediate- (1-
6 month) Term
Dermal
Long-Term
(>6 months)
Inhalation
Short- (1-30 days)
& Intermediate- (1-
6 month) Term
Inhalation
Long-Term (>6
months)
Cancer (oral,
dermal, inhalation)
Point of
Departure
Uncertainty
Factors
RfD
Level of
Concern
Study and Toxicological Effects
An acute endpoint was not selected based on the absence of an appropriate endpoint attributable to a
single dose.
NOAEL=
150
mg/kg/day
NOAEL=
150
mg/kg/day
LTFA= 10X
LTFH=10X
LTFS=10X
LTFA= 10X
LTFH= 10X
cRfD =
0.15
mg/kg/day
Residential
LOG for
MOE = 100
Developmental toxicity study- rat (MRID 41390401)
Maternal LOAEL (mg/kg/day): 750
based on decreased body weight gain (63% GD 7-9)
and food consumption (19.3% GD 7-9). No
developmental toxicity was observed above the limit
dose.
Developmental toxicity study- rat (MRID 41390401)
Maternal LOAEL (mg/kg/day): 750
based on decreased body weight gain (63% GD 7-9)
and food consumption (19.3% GD 7-9). No
developmental toxicity was observed above the limit
dose.
A short- and intermediate-term dermal endpoint was not selected due to the lack of systemic toxicity at
1500 mg/kg/day.
Long- term dermal exposure is not expected for Siduron.
NOAEL=
150
mg/kg/day
100%
absorption
LTFA= 10X
LTFH= 10X
Occupational
and
Residential
LOG for
MOE = 100
Developmental toxicity study- rat (MRID 41390401)
Maternal LOAEL (mg/kg/day): 750
based on decreased body weight gain (63% GD 7-9)
and food consumption (19.3% GD 7-9). No
developmental toxicity was observed above the limit
dose.
Long- term inhalation exposure is not expected for Siduron.
Inadequate Information to Assess Carcinogenic Potential.
NOAEL = no observed adverse effect level. LOAEL = lowest observed adverse effect level. UF = uncertainty factor. UFA =
extrapolation from animal to human (interspecies).  UFH = potential variation in sensitivity among members of the human
population (intraspecies). UFS= use of a short-term study for long-term risk assessment. MOE = margin of exposure. LOC =
level of concern. N/A = not applicable.
                                               12

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              3.     Exposure Pathways and Risk Estimates

Dietary Exposure

       Siduron is a non-food use herbicide so there is no expectation of dietary exposures
through food consumption.  However, exposure to siduron in drinking water is anticipated
because of the environmental fate of this chemical: siduron is highly mobile and persistent in the
environment so movement to water is possible. A drinking water assessment was thus conducted
for this chemical. For additional information on the environmental fate of siduron, please refer
to section III Bl  in this document.

       Acute dietary risk was not assessed for siduron based on the absence on an appropriate
endpoint  attributable to a single dose of siduron. Chronic drinking water exposure was estimated
with the Dietary  Exposure Evaluation Model software with the Food Commodity Intake
Database (DEEM-FCID™, Version 2.03), which uses food consumption data from the USDA's
Continuing Surveys of food Intakes by Individuals (CSFII) from 1994-1996 and 1998. The risk
is expressed as a percentage of a maximum acceptable dose (i.e., the dose which the Agency has
concluded will result in no adverse health effects).  This dose is referred to as the reference dose
(RfD). The RfD is equivalent to the NOAEL divided by the appropriate uncertainty factors.

       The chronic exposure estimates for siduron in drinking water are not of concern as they
are below 100%  of the chronic RfD for the U.S. population and all subgroups in the two regional
scenarios selected. In the Florida (surface water) scenario, the Agency estimated infant exposure
to be 13% of the chronic RfD.  In the Pennsylvania (surface water) scenario, the Agency
estimated infant exposure to be 12% of the chronic RfD. In both of the regional (groundwater)
scenarios, the Agency estimated infant exposure to be 2% of the chronic RfD.

Residential (Non-Occupational) Exposure and Risk

       The anticipated use patterns and current labeling include two short-term (1-30 days)
residential handler exposure scenarios. Intermediate- (1-6 months) and long-term exposures are
not expected based on the sporadic nature  of siduron application by homeowners.  Residential
post-application  exposures are also  anticipated following applications at residential sites by
commercial pesticide handlers and residential handlers.

       Residential handler risk estimates were calculated using a margin of exposure (MOE)
approach for short- and intermediate-term  inhalation risks. MOE is determined by dividing the
toxicological endpoint of concern by the estimated exposure.  The MOE is typically compared to
the level of concern (LOG), usually the product of all of the appropriate uncertainty factors. In
this case, the Agency LOG for inhalation risk is 100, so there are no risk concerns from
inhalation for the residential handler scenarios because the MOEs for residential handlers are
well above the Agency's LOG (2,000,000  for loading/applying granulars with a push-type
spreader and 610,000 for loading/applying granulars with a belly grinder).

       Incidental oral risks were  estimated for toddler post-application exposure for three
scenarios (hand to mouth activity on turf, object to mouth activity on turf, and incidental  soil
                                           13

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ingestion).  The incidental oral MOEs for toddlers are all above the Agency's LOG of 100, and
thus, are not of risk concern (MOEs of 840, 3,330, and 250,000 respectively).  In addition, the
total combined incidental oral exposure risk for toddlers is not of concern for applications of
siduron at the maximum labeled residential application rate of 12 Ibs a.i./acre (MOE of 670).
Post-application incidental ingestion of siduron granules by toddlers from pesticide-treated
residential areas was not assessed because an acute dietary (oral) endpoint was not identified.

       Dermal risk was not quantified for residential or occupational handler or post-application
scenarios due to the lack of systemic toxicity  at 1500 mg/kg/day in the 1991 21-day dermal study
in rabbits (MRID 42107101).  Risk is not expected as siduron is not a dermal sensitizer and is
also classified as having low toxicity for the dermal pathway of exposure (Category IV).

Aggregate Exposure and Risk

       The Agency also considered the potential aggregate risks from drinking water and
residential routes of exposure. As mentioned earlier in the discussion of dietary exposure and
risk, chronic risk of exposure to siduron in drinking water is not of concern. Since the residential
risk assessments show ample margins of exposure, aggregate risk is not likely to be a concern.

Cumulative Risk Characterizing/Assessment

       EPA has not identified a common mechanism of toxicity for siduron and any other
substances.  Siduron does not appear to produce a toxic metabolite produced by other substances.

Occupational Exposure and Risk

       The occupational scenarios associated with siduron use were classified as having
potential short-term and intermediate-term exposures. Long-term exposures are not expected to
occur because of siduron's use pattern.

       Occupational handler risk estimates were calculated using a MOE approach for inhalation
risks. The Agency's LOG for inhalation risk  is 100, and there are risk concerns for two of the
scenarios involving mixing/loading/applying  the 50% wettable powder formulation without a
respirator. However, with the addition of a quarter-face dust/mist respirator, MOEs were above
the Agency's LOG.

       Table 6 summarizes the occupational handler short- and intermediate-term inhalation
risks for siduron.
                                           14

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Table 6: Occupational Handler Short- and Intermediate-term Dermal Inhalation Risks
Exposure Scenario
Mixing/loading wettable
powders for aerial
applications
Mixing/loading wettable
powders for chemigation
applications
Crop or Target
turf: grown for grass
seed and sod
turf: grown for grass
seed and sod
Application
Rate (Ib
a.i./acre)
12
12
Area
Treated
Daily
(acres)
350
350
MOEs (LOC= 100)
Baseline PPE
(single layer
with chemical
resistant gloves)
58
58
Baseline PPE
plus quarter-
face dust/mist
respirator
290
290
       The Agency assumes that inhalation exposures are minimal following outdoor
applications of an active ingredient with low vapor pressure. Since siduron is applied only in
outdoor settings and has a very low vapor pressure (< 0.0008 mm Hg; 4xlO"9 Torr), post-
application inhalation exposures and risks were not assessed

       Dermal exposure and risk was not quantified for occupational handler scenarios due to
the lack of systemic toxicity at the highest dose tested, 1500 mg/kg/day in the 1991 21-day
dermal study in rabbits. Once again, risk is not expected for this exposure pathway due to
siduron's low dermal toxicity and because this chemical is not a dermal sensitizer. Post-
application dermal  exposures and risks were not assessed, since no toxicological endpoint of
concern was identified for dermal exposures.

Endocrine Disruption

       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, 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.  When the appropriate screening and/or testing protocols being
considered under the Agency's Endocrine Disrupter Screening Program (EDSP) have been
developed and vetted, "siduron" may be subjected to additional screening and/or testing to better
characterize effects related to endocrine disruption.

Incident Reports

       There were  some reports of ill effects from exposure to siduron in the available incident
databases. The OPP Incident Data System (IDS) listed two reported incidents involving siduron
submitted to OPP since 1992.  One individual reported weakness, headache,  and dizziness two
hours after applying a siduron product, and this person was treated in an emergency room.  In the
second case, an individual inhaled the product and reported nausea, loss of hand coordination,
                                       15

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difficulty breathing, and slurred speech.  Several cases were reported to the National Poison
Control Centers (PCC) between 1993 and 2003: one case in the Occupational Class involving
moderate symptoms of abdominal pain and bronchospasm; nine cases in the Non-Occupational
Class were reported, but only one presented mild symptoms; and twenty-five cases were
suspected of exposure in the Children's Group, where nine were followed and presented no
symptoms.  One incident was reported to the California Department of Pesticide Regulation
since 1982, where a grower applied the product by sprinkler irrigation and reported a red and
painful left eye and blurred vision.

       Siduron is not on the list of the top 200 chemicals for which the National Pesticide
Information Center (NPIC) received calls from 1984 to 1991, and siduron was not reported to be
involved in human incidents. Out of 5,899 cases reported to the National Institute of
Occupational Safety and Health's Sentinel Event Notification System for Occupational Risks
(NIOSH SENSOR) from 1998 to 2003, none involved siduron.

       B.      Environmental Risk Assessment

       Environmental fate studies are available and acceptable  for the siduron risk assessment.
Ecotoxicity guideline studies are available for a number of the data requirements, but data gaps
exist for chronic toxicity for freshwater and marine/estuarine fish and aquatic invertebrates as
well as for toxicity to aquatic vascular plants. Toxicity data from other phenylurea compounds
similar to siduron were used to estimate chronic risk to fish and aquatic invertebrates and aquatic
vascular plants, so the Agency is not requiring any additional ecological data at this time.  No
acceptable 2-generation mammalian reproduction  studies were  available for estimating chronic
risk. Toxicity data from a rat developmental study was used to  estimate mammalian chronic risk
in the final  ecological risk assessment instead of using surrogate data from another chemical in
the phenylurea class of pesticides, which  had been used previously in the preliminary
assessment. The full assessment, Ecological Risk Assessment Chapter for the Reregistration
Eligibility Decision on Siduron, dated May 2008, is  available on the internet and in the public
docket at www.regulations.gov (EPA-HQ-OPP-2007-0973).

              1.     Environmental Fate and Transport

       Siduron is resistant to hydrolysis,  photolysis in water and on soil, and soil metabolism
under aerobic and anaerobic conditions.  The primary degradate was not identified but detected
at up to 8.1% of the applied radioactivity  of the two soils tested, and  2-methylcyclohexylamine,
a secondary degradate, accounted for 2.1% of the applied radioactivity. Siduron degrades slowly
under laboratory conditions across a range of degradation routes so degradates are not expected
to form in significant quantities. Siduron does however,  have the potential to accumulate in soil
over time because of its persistence in the environment.

       The major routes of siduron dissipation include movement in soils and sediments, and
dilution. Depending on the soil, site, and meteorological conditions, siduron may be transported
off-site via runoff, leaching, and drift. Terrestrial  field studies in California show siduron
leaching 6 to  12 inches in depth in a loamy sand site and 12 to 18 inches in depth in a sandy loam
                                           16

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site, both under bare soil conditions.  Given siduron's mobility and persistence, movement to
ground water is possible. A drinking water assessment was conducted for this chemical.

              2.      Ecological Exposure and Risk

       Ecological risk is characterized by types of effects a pesticide can potentially produce in
an animal or plant, and this characterization is typically based upon registrant-submitted studies
describing acute and chronic effects for different plant and wildlife species. Acceptable
ecotoxicity data are available for birds, mammals, terrestrial invertebrates, and terrestrial plants
for consideration in the siduron ecological risk assessment. Acute studies offish and aquatic
invertebrates are also available, but there are no studies available for chronic risk to these
organisms.

       The Risk  Quotient (RQ) approach is used to estimate the potential for adverse effects
associated with the use of siduron.  The basis of the RQ approach is a  comparison of the
exposure concentrations to toxicity endpoints. Specifically, estimated environmental
concentrations (EECs) are divided by acute and chronic toxicity values to calculate RQs. RQs
are then compared to the Agency's LOCs, and if the RQs exceed the LOCs, the Agency
presumes  there is a potential to affect species in that taxa.   Laboratory environmental fate,
laboratory ecological effects, and use data provide the basis for these risk quotients. Risk
characterization provides additional information on the likelihood of adverse effects by
considering the fate of the chemical in the environment, communities  and species potentially at
risk, their spatial and temporal distributions,  and the nature of the effects observed in studies.
Table 6 summarizes EPA's levels of concern and associated risk presumptions.
Table 6. EPA's Levels of Concern and Associated Risk Presumptions
Risk Presumption
Acute Risk - there is potential for acute risk
Acute Endangered Listed Species -
endangered species may be adversely affected
Chronic Risk - there is potential for chronic
risk
LOC
terrestrial
animals
0.5
0.1
1
LOC
aquatic animals
0.5
0.05
1
LOC
Plants
1
1
Not Assessed
       A.     Terrestrial Organisms

       Siduron is mobile and persistent in the environment in terrestrial systems, so it is
appropriate to model terrestrial dietary residues. Terrestrial exposure for animals was modeled
using TREX, which calculates the dietary and dose-based estimated environmental concentration
(EEC) for birds and mammals. TerrPlant was used to model terrestrial plant exposure.
                                            17

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Birds

       The acute oral toxicity of siduron to the Northern bobwhite quail (Colinus virginiand)
was assessed in a single-dose study with a 14-day observation period.  No mortalities were
observed in either the control or treatment groups. With the resulting LD50 >2250 mg a.i./kg-bw,
siduron can be classified as practically non-toxic to birds on an acute oral exposure basis.  Sub-
acute dietary toxicity studies of siduron on the mallard duck and the Northern bobwhite quail
were also considered for the risk assessment.  These studies yielded LD50 values of >2250 ppm
a.i. for the mallard duck study and >5620 ppm a.i. for the bobwhite quail study and mortality was
not observed at these highest doses tested, so siduron may be classified as practically non-toxic
to birds on an acute dietary basis.

       Avian LD50 values were adjusted to account for bird weight, and these adjusted values
were compared to the EECs for each siduron use scenario.  Most of the siduron use scenarios
yielded EECs below the weight adjusted avian LDso values, which indicates that acute risk is not
expected for these scenarios. The EECs for small birds feeding on short grass and broadleaf
plants/small insects for the 12  Ib a.i/acre scenario are above the adjusted LD50 values (>3280.03
mg/kg-bw and > 1845.02 mg/kg-bw respectively), and several of the EECs for the specialty golf-
course use (22 Ibs a.i./acre) are above the adjusted LDso values.  Although some siduron uses
result in values that exceed the Agency's LOG, this is not necessarily indicative of risk since
there were no mortalities at the highest level tested.

       A dietary reproduction study of the bobwhite quail was considered in order to assess the
risk associated with chronic avian exposure to siduron.  The study yielded a LOAEC of 6250
ppm a.i. and a NOEAC of 2800 ppm a.i, and when compared to the control, there were no
treatment related effects on any of the reproductive parameters measured. The RQ values exceed
the chronic LOG of 1.0 for specialty applications to golf course greens for species that consume
short grasses, tall grasses, or broadleaf plants/small insects (RQs of 4.09, 1.87, and 2.30
respectively) and the LOG  is minimally exceeded for the 12 Ib a.i./A application rates for birds
that consume short grass (RQ = 1.03). Although the RQ values suggest chronic risk  to birds may
exist for these scenarios, it is important to  note the RQ values only exceed the LOG by  a small
margin.

Mammals

       The acute LDso (>5000 mg a.i/kg-bw) for mammals is based on an acute oral toxicity
study (rat). There were no mortalities observed at this highest level which suggests siduron is
practically non-toxic to mammals on an acute oral basis.

       Mammalian LDso values were adjusted to account for mammal weight, and these adjusted
values were compared to the EECs for each siduron use scenario.  Most of the siduron uses
yielded EECs below the weight adjusted mammalian LD50 values, which indicates that acute risk
is not expected for these scenarios. The only acute LOG exceedences for mammals were for the
specialty application to golf course greens, where the RQs for mammals weighing 15g  and 35g
and consuming short grass slightly exceed the Agency's LOG of 0.5 (0.99 and 0.86
respectively). While this use presents values that exceed the Agency's LOG, this is not
necessarily indicative of risk since there were no mortalities at the highest level tested.
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       Since no two-generation reproduction study was submitted for siduron, the NOAEL value
for a two-generation study on another phenylurea chemical (linuron) was examined in the
preliminary ecological assessment from October 2007 for estimating chronic mammalian risk.
However, in registrant-submitted comments to the Agency, it was noted that toxicity data was
available for siduron from a developmental study. The data from the developmental study were
used in the final ecological risk assessment instead of the surrogate approach. Using the data
from the developmental study, the chronic LOG of 1 is still exceeded for all uses for species
consuming short grass, tall grass, and broadleaf plants/small insects with RQs values of 3.82,
1.75, and 2.15 respectively. Although the RQ values suggest chronic risk to mammals may exist
for these scenarios, it is important to note the RQ values only exceed the LOG by a small margin.

Non-Target Insects

       Acute contact honeybee studies indicate that siduron is practically non-toxic to honey
bees (LD50 =120 jig/bee).  However, due to the high application rates associated with some
siduron uses and use patterns, EECs are expected to be higher than the LDso.  Therefore, the risk
of direct adverse effects to terrestrial invertebrates is possible.

Terrestrial Plants

       Tier II seedling emergence studies demonstrate the potential for siduron to affect
terrestrial monocot and dicot plants. The NOAELs were 0.19 and  1.5 Ibs a.i./A for dicots (pea)
and monocots (onion) respectively, which is well below the typical, and labeled,  application rates
for siduron.  Risk is expected for non-target terrestrial plants based on the seedling emergence
studies and given siduron's likely mechanism of action and use pattern, as discussed earlier in
Section IIC.  Vegetative vigor studies have not been submitted for siduron, and the Agency is not
requiring these  studies because the Tier II studies provide adequate information for the risk
assessment of siduron at this time.

       B.    Aquatic Organisms

       Tier II modeling (PRZM/EXAMS) was used to generate estimated environmental
concentrations (EECs) for siduron in surface water reflecting actual use patterns. The Tier II
aquatic exposure modeling scenario assumptions for siduron are as follows: a 10-hectare field is
treated using the maximum application pattern, and that this area borders a 1 hectare pond that is
2 meters deep having no outlet.  While such assumptions adequately estimate typical use for
siduron on sod farms, they are highly conservative for residential/homeowner settings. Golf
course adjustment factors were used to account for the area of golf courses actually treated with
siduron.

       Limited monitoring data on the concentrations of siduron in surface water were available
for assessment.  The frequency and length of sampling, however, were not sufficient to represent
the temporal and special requirements for regulatory purposes.  The modeling for water
concentration was thus conducted with the purpose of supplementing the monitoring data.
                                           19

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       Data are limited but sufficient for the assessment of acute risk to aquatic organisms. No
aquatic chronic toxicity tests were submitted and none were found in the open literature, so
toxicity endpoints were extrapolated using acute-to-chronic ratios (ACRs) or from other
phenylurea compounds.  The Agency is thus not requiring the registrant to conduct chronic
studies on siduron since the extrapolated data is sufficient for the risk assessment at this time.

Freshwater Fish

       Acute toxicity of siduron to freshwater fish was assessed using 96-hour acute toxicity
studies on the rainbow trout (Oncorychus mykiss) and the bluegill sunfish (Lepomis
macrochirus).  The most sensitive 96-hr LCso reported was for rainbow trout, with a value of
8,100 ppb a.i, but the acute 96 hr no observed adverse effects concentration (NOAEC) for
freshwater fish was considered to be 2,590 ppb a.i. since no mortality or sub-lethal effects were
observed at or below this concentration. The RQ values for each of the siduron application
scenarios range between 0.05 and 0.1.  Based upon the slope of the dose-response curve and
since the Agency's LOG was only exceeded by a narrow margin, acute risk to freshwater fish is
not expected.

       Since no chronic toxicity data were submitted for siduron, a chronic study of diuron was
used for the assessment (MRID 00141636). Diuron is a phenylurea with a similar chemical
structure and mechanism of action as siduron, so the diuron ACR of 538 was used as a
conservative ACR factor for extrapolating a siduron early life stage NOAEC from the most
acutely sensitive siduron endpoint (rainbow trout). The NOAEC was established at 15 ppb a.i.,
and this was used to calculate the chronic RQ values for each siduron use scenario.  All uses of
siduron exceed the chronic LOG (RQ > 1) for freshwater fish with RQ values ranging from 5.1 to
55.6, so chronic risk to freshwater fish  is expected.

Freshwater Aquatic Invertebrates

       Acute toxicity of siduron to freshwater invertebrates was assessed using a study in the
waterflea (Daphnia magna\ which resulted in a 48-hour ECso > 13,700 ppb a.i., the highest
concentration tested in the study. The RQ values for each of the siduron application scenarios
range between 0.05 and 0.1. Based upon the slope of the dose-response curve and since the
Agency's LOG was only exceeded by a narrow margin, acute risk to  freshwater aquatic
invertebrates is not expected.

       There was no reproduction NOAEC for the waterflea, and a NOAEC could not be
extrapolated using another phenylurea because there was no definitive acute 48-hour ECso value.
However,  based on the sensitivity pattern of the waterflea to siduron  and other phenylureas and
the range in reproduction NOAEC values, the lowest phenylurea waterflea reproduction value of
6 ppb was used for siduron as a conservative estimate of its reproductive effects level and this
was used to calculate the chronic RQ values for each siduron use scenario.  All uses of siduron
exceed the chronic LOG (RQ > 1) for freshwater aquatic invertebrates, with RQs ranging from
15.1 to 139.7, so chronic risk to freshwater aquatic invertebrates is expected.
                                           20

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Marine/Estuarine Fish

       An acute toxicity study of the Sheepshead minnow (Cyprinodon variegates) resulted in a
96-hr LC50 of 12,300 ppb, indicating that siduron is slightly toxic to estuarine/marine fish upon
acute exposure. The 96-hr NOAEC was 6,300 ppb a.i since there was no mortality or sub-lethal
effects observed at or below this concentration. The RQ values for each of the siduron
application scenarios range between 0.05 and 0.1. Based upon the slope of the dose-response
curve and since the Agency's LOG was only exceeded by a narrow margin, acute risk to
marine/estuarine fish is not expected.

       Since no chronic toxicity data were submitted, the diuron ACR of 538 was used to
extrapolate a conservative early life stage Sheepshead minnow NOAEC using the siduron
Sheepshead minnow acute value. The NOAEC was established at 23 ppb a.i., and this was used
to calculate the chronic RQ values for each siduron use scenario. All uses of siduron exceed the
chronic LOG (RQ > 1) for marine/estuarine fish with RQ values ranging from 3.3 to 36.3, so
chronic risk to marine/estuarine fish is expected.

Marine/Estuarine Aquatic Invertebrates

       The acute study on the oyster resulted in a 48-hr EC50 estimated to be greater than 10,800
ppb a.i., which classifies siduron as no more than slightly toxic to Eastern oyster larvae.  The 48-
hr NOAEC was 10,800 ppb a.i.  The RQ values for each of the siduron application  scenarios
range between 0.06 and 0.13. Based upon the slope of the dose-response curve and since the
Agency's LOG was  only exceeded by a narrow margin,  acute risk acute risk to marine/estuarine
aquatic invertebrates is not expected.

       Since no chronic toxicity data were submitted, the NOAEC was extrapolated from the
marine/estuarine invertebrate M. bahia.  The NOAEC was established at 4.6 ppb a.i., and this
was used to calculate the chronic RQ values for each siduron use scenario. All uses  of siduron
exceed the chronic LOG (RQ > 1) for marine/estuarine aquatic invertebrates with RQ values
ranging from 16.9 to 115.9, so chronic risk to marine/estuarine aquatic invertebrates is expected.

Aquatic Plants

       A growth and reproduction study of non-vascular aquatic plants (green algae) resulted in
a 5 day ECso of 220  ppb a.i. with an associated NOAEC of 24 ppb a.i, .  There was no toxicity
data submitted for vascular aquatic plants, but by comparing siduron to chemicals with a similar
aquatic algae toxicity profile, the Agency determined that vascular plants may be up to 10 times
more sensitive to siduron than non-vascular plants.  The toxicity endpoint for freshwater aquatic
plants was extrapolated using this information, which yielded an ECso = 21.0 ppb.

       The RQs calculated for freshwater non-vascular plants (algae) slightly  exceed the
Agency's LOG for several application scenarios, and the RQ values above the Agency's LOG
range from 1.28 to 3.82. Based on the extrapolated toxicity value for freshwater vascular aquatic
plants,  the RQ values exceed the LOG for all of the use scenarios (RQs range from 3.74 to
40.01). Acute risk is expected for aquatic plants.
                                           21

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       Table 7 presents a summary of the most sensitive endpoints and RQ values used in the
siduron risk assessment.
Table 7: Most Sensitive Endpoints Used in the Siduron Risk Assessment and Highest RQ Values
Environment
Aquatic
Terrestrial
Taxa
Freshwater Fish
Freshwater
Invertebrates
Estuarine/Marine
Fish
Estuarine/Marine
Invertebrates
Plants
Avian
Mammalian
Plants
Type of
Risk
Acute
Chronic
Acute
Chronic
Acute
Chronic
Acute
Chronic
Acute
Acute
Chronic
Acute
Chronic
Acute
Listed
Type of
Endpoint
LC50
NOAEC
EC50
NOAEC
LC50
NOAEC
EC50
NOAEC
EC50
LD50
NOAEC
LD50
NOAEC
EC25
NOAEL
Endpoint
8,100
15
>13,700
6
12,300
23
6,500
4.6
21.0
> 2,250
2,800
>5,000
150
0.18
0.19
Units
ppb a.i.
ppb a.i.
ppb a.i.
ppb a.i.
ppb a.i.
ppb a.i.
ppb a.i.
ppb a.i.
ppb a.i.
mg a.i./kg-bw
mg a.i./kg-diet
mg a.i./kg-bw
mg a.i./kg-bw
Ib a.i./ A
Ib a.i./ A
RQ
0.10
55.63
0.06
139.72
0.07
36.28
0.13
182.24
40.01
8.05
4.09
0.99
3.82
15.4
24.32
Endangered Species

       The Agency's screening-level assessment indicates the possibility of direct effects to
listed aquatic plants, terrestrial and semi-aquatic monocot plants, semi-aquatic dicot plants, and
insects. In addition affects to birds and mammals are expected for chronic exposure. While the
RQ values for freshwater fish and marine/estuarine invertebrates exceed the listed-species LOG,
based on the slope of the dose response curve, acute exposure to siduron is not likely to
adversely affect these taxonomic groups. Potential indirect effects to any species dependent
upon a species that experiences effects from use of siduron cannot be precluded based on the
screening level ecological risk  assessment.  These findings are based solely on EPA's screening
level assessment and do not constitute "may affect" findings under the endangered species act.

Incident Reports

       There are no reports of ecological incidents for siduron in the Environmental Incident
Information System (EIIS) database.
                                           22

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IV.    Risk Management and Reregi strati on Decision

       A.     Determination of Reregi strati on Eligibility

       Section 4(g)(2)(A) of FIFRA calls for the Agency to determine, after submission of
relevant data concerning an active ingredient, whether or not products containing the active
ingredient are eligible for reregi strati on.  The Agency has previously identified and required the
submission of the generic (i.e., active ingredient-specific) data required to support reregi strati on of
products containing siduron as an active ingredient.  The Agency has completed its review of
these generic data, and has determined that the data are sufficient to support reregi strati on of all
products containing siduron.

       The Agency has completed its assessment of the human health and ecological risks
associated with the use of pesticide products containing siduron.  The Agency has determined that
siduron products are eligible for reregi strati on provided the risk mitigation measures outlined in
this document are adopted and label amendments are made to implement these mitigation
measures, as outlined in Chapter V. Appendix A summarizes the uses of siduron that are eligible
for reregistration.  Appendix B identifies the generic data that the Agency reviewed as part of its
determination of reregistration eligibility of siduron, and lists the submitted studies that the
Agency found acceptable. Data gaps are identified as generic data requirements that have not
been satisfied with acceptable data. Should a registrant fail to implement any of the reregistration
requirements identified in this document, the Agency may take regulatory action to address these
concerns.

       B.     Requirements for Reregistration

       Siduron products are eligible for  reregistration provided that registrants comply with the
requirements outlined in this document including the following:  (1) submit required data  and (2)
implement risk mitigation measures.

              1.      Required Data

Siduron products are eligible for reregistration provided that registrants submit data as required by
the product-specific data call-ins that EPA intends to issue as a result of this RED (see Section V).
The generic database supporting the reregistration of siduron uses has been reviewed and
determined to be adequate to support a reregistration eligibility decision.  However, the Agency is
now requiring a UV/visible absorption spectrum study for all pesticide chemicals as additional
characterization of the  active ingredient's properties.
              2      Risk Mitigation

       Products containing siduron are eligible for reregistration provided the specific labeling
requirements required in Table 7 are reflected on the siduron labels.
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C.     Regulatory Rationale

       The Agency has determined that siduron is eligible for reregi strati on provided that the
requirements for reregi strati on outlined in this document are implemented.  Provided that
registrants comply with the requirements of this RED, EPA believes that siduron will not present
risks inconsistent with FIFRA.
              1.     Human Health and Ecological Risk

       EPA has conducted human health and ecological risk assessments for siduron to support
the reregi strati on eligibility decision. In its assessments, EPA concluded that most risk estimates
are below the Agency's level of concern, but also identified some potential risks that, if left
unmitigated, may pose risks or adverse effects to humans or the environment.

       All human health risk estimates are below the Agency's level of concern with the
exception of inhalation risk from mixing/loading wettable powders for chemigation. To mitigate
this risk, the Agency is requiring a NIOSH-approved dust/mist filtering respirator with
MSHA/NIOSH approval number prefix TC-21C or a NIOSH-approved respirator with any N, R,
P, or HE filter.

       In EPA's ecological risk assessment, several exceedances were estimated from use of
siduron, specifically concerning acute risk to non-target plants and chronic risk to fish and aquatic
invertebrates. To mitigate these ecological risks, the Agency is requiring language to reduce spray
drift; requiring an environmental hazard statement addressing the toxicity of siduron to fish and
aquatic invertebrates; limiting band-treatments to golf courses to 6 applications per year; advising
users that non-target plants can be adversely affected by siduron; and prohibiting aerial
application of siduron.

       Although there are also some exceedances of the LOG for birds and mammals,  the RQs for
these taxonomic groups only slightly exceeded the Agency's LOG.  However, based on the slope
of the dose-response curves from the bird and mammal studies, unacceptable risk is not expected.
In addition, the potential for risk is based on the assumption that birds and mammals are feeding
exclusively within golf courses, sod farms, and residential properties that use siduron on turf. To
the extent that those birds and mammals do not reside exclusively and permanently within the
area, exposure will be less and risk is presumably less.

              2.     Endangered Species

       The Agency has developed the Endangered Species Protection Program to identify
pesticides whose use may cause adverse impacts on endangered and threatened species and to
implement mitigation measures that address these impacts. The Endangered Species Act (ESA)
requires federal agencies to ensure that their actions are not likely to jeopardize listed species or
adversely modify designated critical habitat. To analyze the potential  of registered pesticide uses
that may affect any particular species, EPA uses basic toxicity and exposure data and considers
                                       24

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ecological parameters, pesticide use information, geographic relationship between specific
pesticide uses and species locations, and biological requirements and behavioral aspects of the
particular species. When conducted, these analyses take into consideration any regulatory
changes recommended in this RED being implemented at that time.

       The ecological assessment that EPA conducted for this RED does not, in itself, constitute a
determination as to whether specific species or critical habitat may be harmed by the pesticide.
Rather, this assessment serves as a screen to determine the need for any species-specific
assessment that will evaluate whether exposure may be at levels that could cause harm to specific
listed species and their critical habitat. The species-specific assessment refines the screening-level
assessment to take into account information such as the geographic area of pesticide use in
relation to the listed species and the habits and habitat requirements of the listed species.  If the
Agency's specific assessments for the pesticidal use of siduron result in the need to modify use of
the pesticide, any geographically specific changes to the pesticide's registration will be
implemented through the process described in the Agency's Federal Register Notice (54 FR
27984) regarding implementation of the Endangered Species Protection Program.

       Risk findings are based solely on EPA's qualitative assessment for siduron and do not
constitute "may affect" findings under the ESA. A determination that there is a likelihood of
potential effects to a listed species may result in limitations on the use of the pesticide, other
measures to  mitigate any potential effects, and/or consultations with the Fish and Wildlife Service
or National Marine Fisheries Service, as necessary. If the Agency determines use of siduron "may
affect" listed species or their designated critical habitat, EPA will employ the provisions in the
Services  regulations (50 CFR Part 402).
              3.     Endocrine Screening
       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,
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.  When the appropriate screening and/or testing protocols being considered under the
Agency's Endocrine Disrupter Screening Program (EDSP) have been developed and vetted,
"siduron" may be subjected to additional screening and/or testing to better characterize effects
related to endocrine disruption.
                                            25

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V.     What Registrants Need to Do

       The Agency has determined that the products containing siduron are eligible for
reregi strati on provided that the mitigation measures and label changes identified in this RED are
implemented. Registrants will need to amend their product labeling to incorporate the label
statements set forth in the Label Changes Summary Table 8.  The Agency intends to issue a Data
Call-in (DCI) requiring product-specific data.  Generally, the registrant will have 90 days from
receipt of a DCI to complete and submit response forms or request time extensions and/or waivers
with a full written justification.  For product-specific data, the registrant will have eight months to
submit data and amended labels.

       A.    Manufacturing Use Products

              1.      Additional Generic Data Requirements

       The generic database supporting the reregi strati on of the pesticidal use of siduron has been
reviewed and determined to be substantially complete.  The human health risk assessment
identified a data gap for UV/Visible Light Absorption, guideline number 830.7050. This is a new
data requirement which is being required of all pesticide chemicals as additional
characterization of the active ingredient's properties.


             2.      Labeling for Technical and Manufacturing Use Products

       To ensure compliance with FIFRA, manufacturing-use product (MUP) labeling should be
revised to comply with all current EPA regulations, PR Notices, and applicable  policies. The
MUP labeling should bear the labeling contained in Table 8.

       B.    End-Use Products

              1.      Additional Product-Specific Data Requirements

       Section 4(g) (2) (B) of FIFRA calls for the Agency to obtain any needed product-specific
data regarding a pesticide after a determination of eligibility has been made. The registrant must
review previous data submissions to ensure 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
instructions in the Requirement  Status and Registrations Response Form provided for each
product.

       A product-specific data call-in, outlining specific data requirements will be issued in the
near future.

             2.      Labeling for End-Use Products
                                            26

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       To be eligible for reregi strati on, labeling changes are necessary to implement measures
outlined in Section IV.  Specific language to incorporate these changes is specified in Table 8.
Generally, conditions for the distribution and sale of products bearing old labels/labeling will be
established when the label changes are approved. However, specific 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.

       C.    Labeling Changes Summary Table

       In order to be eligible for reregi strati on, amend all product labels to comply with the
following table. Table 8 describes how language on the labels should be amended.
                                            27

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Table 8: Labeling Changes Summary Table
In order to be eligible for reregi strati on, amend all product labels to incorporate the risk mitigation measures outlined in Section IV.
The following table describes how language on the labels should be amended.
                                 Table 8: Summary of Labeling Changes for Siduron (PC 035509)
                                                 Manufacturing Use Products
      Description
                  Amended Labeling Language '
        Placement on Label
 For all Manufacturing
 Use Products
"Only for formulation into an herbicide for the following use(s) [fill
blank only with those uses that are being supported by MP registrant]."
Directions for Use
 One of these statements
 may be added to a label
 to allow reformulation
 of the product for a
 specific use or all
 additional uses
 supported by a
 formulator or user
"This product may be used to formulate products for specific use(s) not
listed on the MP label if the formulator, user group, or grower has
complied with U.S. EPA submission requirements regarding support of
such use(s)."

"This product may be used to formulate products for any additional
use(s) not listed on the MP label if the formulator,  user group, or grower
has complied with U.S. EPA submission requirements regarding support
of such use(s)."
Directions for Use
                                                              28

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Environmental Hazards
Statements Required
by the RED and
Agency Label Policies
"Do not discharge effluent containing this product into lakes, streams,
ponds, estuaries, oceans, or other waters unless in accordance with the
requirements of a National Pollution Discharge Elimination System
(NPDES) permit and the permitting authority has been notified in writing
prior to discharge. Do not discharge effluent containing this product to
sewer systems without previously notifying the local sewage treatment
plant authority.  For guidance contact your State Water Board or
Regional Office of the EPA."
Precautionary Statements
                                          End Use Products Intended &r Occupational"
PPE Requirements
Established by the
RED1
for Granular
Formulations
"Personal Protective Equipment (PPE)"

"All loaders, applicators and other handlers must wear:
 > Long-sleeve shirt and long pants,
 > Shoes plus socks."
Immediately following/below
Precautionary Statements: Hazards to
Humans and Domestic Animals
PPE Requirements
Established by the
RED1
for Wettable Powder
Formulations
"Personal Protective Equipment (PPE)"
"Some materials that are chemical-resistant to this product are"
(registrant inserts correct chemical-resistant material).  "If you want
more options, follow the instructions for category" [registrant inserts
A,B,C,D,E,F,G,or H] "on an EPA chemical-resistance category selection
chart."

"All mixers, loaders, applicators and other handlers must wear:
> Long-sleeve shirt and long pants,
> Chemical-resistant gloves,
> Shoes plus socks."

"In addition, for chemigation:
All mixers and loaders must wear:
> NIOSH-approved  dust/mist filtering respirator with MSHA/NIOSH
approval number prefix TC-21C or a NIOSH-approved respirator with
Immediately following/below
Precautionary Statements: Hazards to
Humans and Domestic Animals
                                                               29

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                        anyN, R, P, or HE filter."
User Safety
Requirements
"Follow manufacturer's instructions for cleaning/maintaining PPE.  If no
such instructions for washables exist, use detergent and hot water. Keep
and wash PPE separately from other laundry."

"Discard clothing and other absorbent materials that have been drenched
or heavily contaminated with this product's concentrate. Do not reuse
them."
Precautionary Statements: Hazards to
Humans and Domestic Animals
immediately following the PPE
requirements
User Safety
Recommendations
"User Safety Recommendations

Users should wash hands before eating, drinking, chewing gum, using
tobacco, or using the toilet.

Users should remove clothing/PPE immediately if pesticide gets inside.
Then wash thoroughly and put on clean clothing.

Users should remove PPE immediately after handling this product.  Wash
the outside of gloves before removing.*  As soon as possible, wash
thoroughly and change into clean  clothing."
Precautionary Statements under:
Hazards to Humans and Domestic
Animals immediately following
Engineering Controls

(Must be placed in a box.)
Environmental Hazards
 "This product is toxic to fish and aquatic invertebrates.  Do not apply
directly to water, or to areas where surface water is present or to intertidal
areas below the mean high water mark. Do not apply where runoff is
likely to occur. Do not contaminate water when disposing of equipment
washwaters or rinsate."
Precautionary Statements immediately
following the User Safety
Recommendations
Restricted-Entry
Interval for products
with directions for use
within scope of the
Worker Protection
Standard for
"Do not enter or allow worker entry into treated areas during the
restricted entry interval (REI) of 4 hours."
Directions for Use, Under Agricultural
Use Requirements Box
                                                               30

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Agricultural Pesticides
(WPS)
Entry Restrictions for
products having
occupational uses on
the label not subject to
the WPS
Entry Restriction for non-WPS uses applied as a liquid::
 "Do not enter or allow others to enter the treated area until sprays have
dried."

Entry Restriction for non-WPS uses applied as a solid):
 "Do not enter or allow others to enter the treated area until dusts have
settled."

Note to registrants-ifthe label requires watering in add this statement:
"If watering in is required after the application, do not enter or allow
others to enter the treated areas (except those involved in the watering)
until the watering-in is complete and the surface is dry."

Note to registrants-ifthe label requires soil incorporation add this
statement:
"If soil incorporation is required after the application, do not enter or
allow others to enter the treated area (except those persons involved in
the incorporation) until the incorporation is complete."
If no WPS uses on the product label,
place the appropriate statement in the
Directions for Use Under General
Precautions and Restrictions. If the
product also contains WPS uses, then
create a Non-Agricultural Use
Requirements box as directed in PR
Notice 93-7 and place the appropriate
statement inside that box.
Early Entry Personal
Protective Equipment
for products with
directions for use
within the scope of the
WPS
"PPE required for early entry to treated areas that is permitted under the
Worker Protection Standard and that involves contact with anything that
has been treated, such as plants, soil, or water, is:
> Coveralls
> Waterproof gloves
> Shoes plus socks
Direction for Use
Agricultural Use Requirements box
                                                                 31

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General Application
Restrictions
"Do not apply this product in a way that will contact workers or other
persons, either directly or through drift. Only protected handlers may be
in the area during application."
Place in the Direction for Use directly
above the Agricultural Use Box.
Other Application
Restrictions (Risk
Mitigation)
"Aerial application is prohibited."

"Non-target plants can be adversely affected by this product."

Golf Course Greens (band-treatment)
"For band-treatments: Do not make more than 6 applications of siduron
(of one product or combinations of products) to golf course greens per
year."
Directions for Use
Spray Drift (for
products applied as a
spray only)
"Spray Drift Requirements"

"Wind Direction and Speed"

"Do not apply when the wind speed exceeds 10 miles per hour at the
application site."

"Temperature Inversion"

 "Do not apply into a temperature inversion or under stable atmospheric
 conditions."

"Droplet Size"

"Apply as a medium or coarser spray (ASABE standard 572)."

 "Release Height"

 "Do not apply with a nozzle height of greater than 4 feet above the
 ground or crop canopy."	
Spray Drift
                                                               32

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      -. •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• -.End Use Products Intended for Residential Use  •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• ••
 Application
 Restrictions
"Do not apply this product in a way that will contact any person, pet,
either directly or through drift. Keep people and pets out of the area
during application."
Directions for Use under General
Precautions and Restrictions
 Entry Restrictions
                           Liquid:
                           "Do not allow people or pets to enter the treated area until sprays have
                           dried."
                           Solid:
                           "Do not allow people or pets to enter the treated area until dusts have
                           settled."
                           Note to registrants-ifthe label requires watering in add this statement:
                           "If watering in is required after the application, do not enter or allow
                           people or pets to enter the treated areas (except those involved in the
                           watering) until the watering-in is complete and the surface is  dry."

                           Note to registrants-ifthe label requires soil incorporation add this
                           statement:
                           "If soil incorporation is required after the application, do not  enter or
                           allow people or pets to enter the treated area (except those persons
                           involved in the incorporation) until the incorporation is complete."
 PPE that is established on the basis of Acute Toxicity of the end-use product must be compared to the active ingredient PPE in this document. The more protective PPE must be
placed in the product labeling.  For guidance on which PPE is considered more protective, see PR Notice 93-7.
                                                                     33

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Appendix A. Use Patterns Subject to Reregi strati on of Siduron (PC Code 035509)
Use Site
Application
Timing
Maximum
Application Rate
Formulation2
Maximum
Number of
Applications
per Year
Minimum
Application
Interval
Application Equipment /Type
TERRESTRIAL NON-FOOD & OUTDOOR RESIDENTIAL USES
sod farms,
golf
courses,
residential
areas,
parks, turf
golf course
greens
at seeding
at seeding
fall plantings/
established
turf
established
turf
6 Ib. a. i. /acre
6 Ib. a. i. /acre
followed 30 days
later by
3 Ib. a. i. /acre
12 Ib. a.i./acre
12 in. band
application of 1 Ib.
per 1,000 sq. ft.
granular
wettable
powder
granular
wettable
powder
granular
wettable
powder
wettable
powder
1
1
2
2
1
1
6
NA
NA
30 days
30 days
NA
NA
30 days
push-type spreader, tractor-drawn
spreader, belly grinder
groundboom, low pressure
handwand, handgun, chemigation
push-type spreader, tractor-drawn
spreader, belly grinder
groundboom, low pressure
handwand, handgun, chemigation
push-type spreader, tractor-drawn
spreader, belly grinder
groundboom, low pressure
handwand, handgun, chemigation
single nozzle sprayer
                                                          34

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Appendix B.  Table of Generic Data Requirements and Studies Used to Make the Reregi strati on
Decision

GUIDE TO APPENDIX B

       Appendix B contains a listing of data requirements which support the reregi strati on for
active ingredients within the siduron case covered by this RED. It contains generic data
requirements that apply siduron in all products, including data requirements for which a "typical
formulation" is the test substance.

The data table is organized in the following formats:

   1.  Data requirement (Column 1).  The data requirements are listed in the order in which they
       appear in 40 CFR 158. The reference numbers accompanying each test refer to the test
       protocols set in the Pesticide Assessment Guidance, which is available from the National
       Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161. (703)
       487-4650.

   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 is no MRTD number has been assigned.  Refer to
the Bibliography appendix for a complete citation of the study.
                                          35

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Appendix B. Table of Generic Data Requirements and Studies Used to Make the Reregi strati on
Decision
Data Supporting Guideline Requirements for the Reregistration of Siduron
New
Guideline
Number
Study Description
Use
Pattern
Citation(s)
TOXICOLOGY
PRODUCT CHEMISTRY
830.6302
830.6304
830.6313
830.6314
830.7000
830.7200
830.7300
830.7370
830.7550
830.7840
830.7950
Color
Physical state
Stability
Oxidation/reduction potential
pH
Melting Point
Density
Dissociation Constants in Water
Octanol Water Partition Coefficient
Solubility
Vapor Pressure
All
All
All
All
All
All
All
All
All
All
All
43587001
43587001
43587001
43587001
43587001
43587001
41933401
43587001
43587001
41277101
41620601
ECOLOGICAL EFFECTS
850.2100
850.2200
850.2200
850.2300
850.1010
850.1075
850.1075
850.1025
850.1035
850.4550
Avian Acute Oral Toxicity
Avian Dietary Toxicity - Quail
Avian Dietary Toxicity - Duck
Avian Reproduction - Quail
Freshwater Invertebrate Toxicity
Freshwater Fish Toxicity Rainbow
Trout
Estuarine/Marine Fish LC50
Estuarine/Marine Invertebrate -
Mollusk
Estuarine/Marine Invertebrate -
Mysid
Algal Plant Toxicity - Freshwater
alga
All
All
All
All
All
All
All
All
All
All
40991601
40991602
40991603
43883301
43327902
43324501
43327902
43385401
45868301
42111002
TOXICOLOGY
870.1100
870.1200
870.1300
870.2400
870.2500
870.3100
870.3200
Acute Oral Toxicity - Rat
Acute Dermal Toxicity - Rabbit/Rat
Acute Inhalation Toxicity - Rat
Primary Eye Irritation - Rabbit
Primary Dermal Irritation - Rabbit
Subchronic Oral Toxicity: 90-Day
Study Rodent
21 -Day Dermal - Rabbit/Rat
All
All
All
All
All
All
All
41933402
41933403
41933404
41933405
41933406
41623601
42627001, 41137201, 42107101
                                         36

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Data Supporting Guideline Requirements for the Reregistration of Siduron
New
Guideline
Number
870.3700A
870.5900
870.5550
870.5385
Study Description
Developmental Toxicity - Rat
Mammalian Cytogenetics
CHO/HPRT Assay
Unscheduled DNA Synthesis in
Mammalian Cells in Culture
Mammalian Chromosome
Aberration
Use
Pattern
All
All
All
All
Citation(s)
41390401
40991611
41050503
41126701
ENVIRONMENTAL FATE
835.1240
835.2120
835.2240
835.2410
835.4100
835.4200
835.6100
850.1730
Adsorption/Desorption
Hydrolysis
Photodegradation - Water
Photodegradation - Soil
Aerobic Soil Metabolism
Anaerobic Soil Metabolism
Terrestrial Field Dissipation
Accumulation in Fish
All
All
All
All
All
All
All
All
41811303
41050501
41811301
41811302
43846701
41618201
42535801
41811305
37

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Appendix C.  Technical Support Documents

       Additional documentation in support of this RED is maintained in the OPP docket EPA-
HQ-OPP-2007-1160. This docket may be accessed in the OPP docket room located at Room S-
4900, One Potomac Yard, 2777 S. Crystal Drive, Arlington, VA. It is open Monday through
Friday, excluding Federal holidays, from 8:30 a.m. to 4:00 p.m. All documents may be viewed
in the OPP docket room or downloaded or viewed via the Internet at the following site:
http://www.regulations.gov.

These documents include:

HEP Document:
Siduron Revised Human Health Risk Assessment for the Reregistration Eligibility Decision.
Dated July 1, 2008.

Siduron: Hazard Characterization andEndpoint Selection Reflecting the Review ofTesticular
Maturation in Prepubertal New Zealand White Rabbits Toxicity Study. May 1, 2008.

Siduron: Chronic Aggregate (Dietary Drinking Water Only) Exposure and Risk Assessment for
the Reregistration Eligibility Decision. Dated August 22, 2007.

EFED Documents:
Ecological Risk Assessment Chapter for the Reregistration Eligibility Decision on Siduron.
DatedMaylS, 2008.
                                          38

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Appendix D. Citations Considered to be Part of the Data Base Supporting the Reregi strati on
Eligibility Decision
 00020661    Todd, G.C.; Kehr, C.C.; West, H.C.; et al. (1972) The Acute Toxicity of EL-103
             in Mice, Rats, Rabbits, Cats, Dogs, Quail, Ducks, Chickens, and Fish.
             (Unpublished study received Mar 13, 1973 under 1471-97; prepared in
             cooperation with Bionomics, Inc.,  submitted by Blanco Products Co., Div. of Eli
             Lilly and Co., Indianapolis, Ind.; CDL:006422-F)

 00041685    Hamelink, J.L.; Kehr, C.C. (1976) The Acute Static Toxicity of Two
             Formulations of Compound 75503, EL-103, to Fathead Minnows (Studies 1012-
             6, 1013-6, 1014-6). (Unpublished study received Feb 18, 1977 under 1471-109;
             submitted by Elanco Products Co., Div. of Eli Lilly and Co., Indianapolis, Ind.;
             CDL:095855-I)

 00041694    Hamelink, J.L.; Todd, G.C.; Brannon, D.R.; et al. (1978) Acute Toxicity of
             Compound 75503  (EL-103) to Daphnia magna: Study 5058-77. (Unpublished
             study received Jun 1, 1978 under 1471- 109; submitted by Elanco Products Co.,
             Div. of Eli Lilly and Co., Indianapolis, Ind.; CDL:097102-C)

 00090083    Sauter, S.; Meyerhoff, R.D.; Todd, G.C.; et al. (1981) The Toxicity of
             Tebuthiuron (EL-103, Compound 75503) in Water to Rainbow Trout in a 45-day
             Embryo-larvae Study: Study F14580. Includes method AM-AA-CA-J024-AB-
             755 dated Jan 26,  1981. (Unpublished study received Dec 10, 1981 under 1471-
             109; submitted by Elanco Products Co., Div. of Eli Lilly and Co., Indianapolis,
             Ind.; CDL:246375-A)

 00090084    Sauter, S.; Meyerhoff, R.D.; Todd, G.C.; et al. (1981) The Toxicity of
             Tebuthiuron (EL-103, Compound 75503) in Water to Fat- head Minnows in a
             33-day Embryo-larvae Study: Study F08381. Includes method AM-AA-CA-
             JO24-AB-755 dated Jan 26, 1981.  (Unpublished study received Dec 10, 1981
             under 1471-109; submitted by Elanco Products Co., Div. of Eli Lilly and Co.,
             Indianapolis, Ind.; CDL:246375-B)

 00138700    Grothe, D.; Meyerhoff, R.; Todd, G.; et al. (1983) The Toxicity of Tebuthiuron
             (EL-103, Compound 75503) to Daphnia magna in a 21- day Static Renewal  Full
             Life-Cycle study: C02882. (unpublished study received Jan 19, 1984 under
             1471-109; submitted by Elanco Products Co., Div. of Eli Lilly and Co.,
             Indianapolis, IN.; CDL:252491-D)

 00141636    Call, D.; Brooke, L.; Kent, R. (1983) Toxicity, bioconcentration, and
             metabolism of five herbicides in freshwater fish. Prepared by Univ. of
             Wisconsin, Center for Lake Superior Environmental studies for the
             Environmental Protection Agency; available from the National Technical
             Information Service. 113 p.
                                         39

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00142932   Hall, C. (1985) 48-Hour EC50 to Daphia magna: [Linuron]: Haskell Laboratory
            Report No. 103-85. Unpublished study prepared by Haskell Laboratory for
            Toxicology and Industrial Medicine. 5 p.

40094602   Johnson, W.; Finley, M. (1980) Handbook of Acute Toxicity of Chemicals to
            Fish and Aquatic Invertebrates: Resource Publication 137. US Fish and Wildlife
            Service, Washington, D.C. 106 p.

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

40445501   Wetzel, J. (1986) Static Acute 96-hour LC50 of Linuron (INZ-326- 118) to
            Rainbow Trout (Salmo gairdneri): Rept. No. HLR 525-86. Unpublished study
            prepared by Dupont Haskell Laboratory. 12 p.

40991601   Grimes, J.; Jaber, M. (1988) Siduron (H # 17,409): An Acute Oral Toxicity
            Study with the Bobwhite: Final Report: Project No. 112-209. Unpublished study
            prepared by Wildlife International Ltd. 19 p.

40991602   Grimes, J.; Jaber, M. (1988) Siduron (H # 17409): A Dietary LC50 Study with
            the Bobwhite: Project No. 112-203; Dupont HLO No. 750-88. Unpublished
            study prepared by Wildlife International Ltd. 27 p.

40991603   Grimes, J.; Jaber, M. (1988) Siduron (H # 17409): A Dietary LC50 Study with
            the Mallard: Project No. 112-204. Unpublished study prepared by Wildlife
            International Ltd. 27 p.

40991611   Bentley, K. (1989) Mutagenicity Evaluation of IN Z1318-70 in the CHO/HRPT
            Assaya: Project ID: Haskell Laboratory Report No. 770-88. Unpublished study
            prepared by E.I.du Pont de Nemours and Co., Inc. 19 p.

40991612   Reynolds, V. (1989) Mutagenicity Testing of IN Z1318-70 in the Salmonella
            typhimurium Plate Incorporated Assay: Project ID: Haskell Laboratory Report
            No. 820-88. Unpublished study prepared by E.I. du Pont de Nemours and Co.,
            Inc. 27 p.

41050501   Chrzanowski, R. (1989) Hydrolysis of Carbon 14|-Siduron in ph 5,7, and 9
            Buffer Solutions: Proj. ID AMR-1280-88. Unpublished study prepared by E.I.
            du Pont de Nemours & Co., Inc. 31 p.

41050503    Bentley, K.  (1989) Assessment of IN Z1318-70 in the in vitro Unscheduled
            DNA Synthesis Assay in Primary Rat Hepatocytes: Proj. ID 53-89. Unpublished
            study prepared by Dupont Haskell Laboratory. 16 p.
                                         40

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41126701    Vlachos, D. (1989) In vitro Evaluation of IN Z1318-70 for Chromo- some
            Aberrations in Human Lymphocytes: Project ID: 175-89: Medical Research No.
            8532-001. Unpublished study prepared by E.I. du Pont de Nemours and Co., Inc.
            22 p.

41137201    Brock, W. (1989) Repeated Dose Dermal Toxicity: 21-Day Study with IN
            Z1318-70 in Rabbits: Project ID: Haskell Laboratory Report No.  165-89.
            Unpublished study prepared by E.I. du Pont de Nemours and Co., Inc. 214 p.

41277101    Hoffman, R. (1988) Determination of the Water Solubility of Siduron, Z1318:
            Lab Project Number: Z1318/C. Unpublished study prepared by E.I. du Pont de
            Nemours and Co., Inc. 15 p.

41390401    Rickard, L.  (1989) Teratogenicity Study  of IN Z1318-70 (Siduron) in the  Rat:
            Lab Project Number: 136-89: 8532-001.  Unpublished study prepared by E. I. du
            Pont de Nemours and Co. 179 p.

41390401    Rickard, L.  (1989) Teratogenicity Study  of IN Z1318-70 (Siduron) in the  Rat:
            Lab Project Number: 136-89: 8532-001.  Unpublished study prepared by E. I. du
            Pont de Nemours and Co. 179 p.

41418801    Boeri, R.  (1987) Static Acute Toxicity of Haskell Sample Number 16, 035 to the
            Mysid, Mysidopsis bahia: Lab Project Number: D1187: HLO 725-87.
            Unpublished study prepared by Enseco Inc. 16 p.

41418803    Drottar, K. (1986) Acute Toxicity of H-16,035 to the Sheepshead Minnow
            (Cyprinodon variegatus): Rev.: Project No. 86342-0400- 2130: HLO 43-87.
            Unpublished study prepared by Environmental Science and Engineering, Inc. 37
            P-

41618201    Rhodes, B. (1990) Anaerobic Soil Metabolism of ?Carbon 14|-Siduron: Lab
            Project Number: AMR-1520-89. Unpublished study prepared by E.I. du Pont de
            Nemours and Co. 51 p.

41620601    Barefoot, A. (1990) Vapor Pressure of Siduron: Lab Project Number: AMR-
            1850-90. Unpublished study prepared by E.I. du Pont de Nemours and Co. 18 p.

41632601    Sherman, H. (1964) Ninety-Day Feeding Study with 1-2-Methyl Cyclo- hexyl-3-
            Phenylurea  INZ-1318: Lab Project Number: 41/64. Unpublished  study prepared
            by E. I. du Pont de Nemours & Company, Inc. 29 p.

41811301    Estigoy, L.; Shepler, K. (1990) Sunlight Photodegradation of Carbon 14-
            Phenyl(U) Siduron in a Buffered Aqueous Solution at Ph 7 by Natural Sunlight:
            Lab Project Number: 217W-1: 217W: 612-90-100- 03-28B-01. Unpublished
            study prepared by Pharmacology and Toxicology Research Laboratory, Inc. 78
            P-
                                        41

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41811302    Estigoy, L.; Shepler, K. (1990) Photodegradation of Carbon 14-Phenyl(U)
            Siduron in/on Soil by Natural Sunlight: Lab Project Number : 218W-1: 218W:
            613-90-100-03-28J-02. Unpublished study prepared by Pharmacology and
            Toxicology Research Laboratory, Inc.  83 p.

41811303    Kesterson, A. (1990) Soil Adsorption/Desorption of Phenyl(U)-Carbon 14
            Siduron by the Batch Equilibrium Method: Lab Project Number: 430: 1290:
            AMR-1787-90. Unpublished study prepared by Pharmacology and Toxicology
            Research Laboratory. 63 p.

41811305    Fackler, P. (1990) Siduron-Bioconcentration and Elimination of Carbon 14-
            Residues by BlueGill (Lepomis macrochirus): Lab Project Number: 654-89-100-
            03-19G-10: 10934-0190-6121-140: 90-8-3415. Unpublished study prepared by
            Springborn Laboratories, Inc. 57 p.

41933401    Keeler, D. (1988) Siduron: Product Identity and Composition and Physical and
            Chemical Characteristics: Lab Project Number: Z1318 Unpublished study
            prepared by E. I. DuPont de Nemours and Co. Inc. 40 p.

41933402    Summers, J. (1990) Acute Oral Toxicity Study With INZ-1318-70 in Male and
            Female Rats: Lab Project Number: HLR 735-88. Unpublished study prepared by
            E. I. DuPont de Nemours and Co. 9 p.

41933402    Summers, J. (1990) Acute Oral Toxicity Study With INZ-1318-70 in Male and
            Female Rats: Lab Project Number: HLR 735-88. Unpublished study prepared by
            E. I. DuPont de Nemours and Co. 9 p.

41933403    Brock, W. (1988) Acute Dermal Toxicity Study of IN Z1318-70 in Rabbits: Lab
            Project Number: 8532-001: 638-88. Unpublished study prepared by E. I. Dupont
            de Nemours and Co., Inc. lip.

41933404    Malek, D. (1989) Acute  Inhalation Toxicity Study with IN Z1318-70 (Milled) in
            Rats: Lab Project Number: 8532-001: 135-89. Unpublished study prepared by E.
            I. DuPont de Nemours and Co., Inc. 4 p.

41933405    Brock, W. (1988) Primary Eye Irritation Study with IN Z1318-70 in Rabbits:
            Lab Project Number: 8532-001: 622-88. Unpublished study prepared by E. I. du
            Pont de Nemours and Co., Inc. 18 p.

41933406    Brock, W. (1988) Primary Dermal Irritation Study with IN Z1318-70 in Rabbits:
            Lab Project Number: 8532-001: 662-88. Unpublished study prepared by E. I. du
            Pont de Nemours and Co., Inc. 10 p.

41965020    Burgess, D. (1988) Chronic Toxicity of UMP-488 to Daphnia magna Under
            Flow-through Test Conditions: Final Report: Lab Project Number: 36737.
            Unpublished study prepared by Analytical Bio- Chemistry Labs., Inc. 336 p.
                                        42

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42046003    Baer, K. (1991) Static, Acute, 48-Hour EC50 of DPX-14740-165 (Karmex DF)
            to Daphnia magna: Lab Project Number: 508-91: MR-9145- 001. Unpublished
            study prepared by E. I. du Pont de Nemours and Co. 26 p.

42061801    Ward, T.; Boeri, R. (1991) Static Acute Toxicity of DPX-Z326-198 (Linuron) to
            the Sheepshead Minnow, Cyprinodon variegatus: Lab Project Number: MR-
            9118-001: 9127-DU: 567-91. Unpublished study prepared by Envirosystems,
            Inc. in coop, with Dupont Haskell Labs. 32 p.

42061803    Ward, T.; Boeri. R. (1991) Static Acute Toxicity of DPX-Z326-198 (Linuron) to
            the Mysid, Mysidopsis bahia: Lab Project Number: MR-9118-001: 9128-DU:
            515-91. Unpublished study prepared by EnviroSystems, Inc., in coop, with
            Dupont Haskell Labs. 31 p.

42061804    Pierson, K. (1991) Flow-Through, 80-Day Toxicity of DPX-Z326-198 to
            Embryo and Larval Rainbow Trout, Oncorhynchus mykiss: Lab Project
            Number: MR-9118-001: 538-91. Unpublished study prepared by Dupont Haskell
            Labs. 426 p.

42107101    Malek, D. (1991) Repeated Dose Dermal Toxicity: 21-Day  Study with IN
            Z1318-70 (Siduron) in Male Rabbits: Lab Project No: 108-91: 8816-001.
            Unpublished study prepared by E.I. du Pont de Nemours and Co., Haskell Lab.
            369 p.

42111001    McKelvey, R.; Kuratle, H. (1991) Influence of Siduron on Seed Germination,
            Seedling Emergence, and  Vegetative Vigor of Several Terrestrial Plants: Lab
            Project Number: AMR 2036-91. Unpublished study prepared by E.I. du Pont de
            Nemours and Co. 196 p.

42132002    Blakemore,  G. (1991) Chronic Toxicity of Thidiazuron to Daphnia magna Under
            Flow-through  Test Conditions: Final Report: Lab Project Number:  39114: 507-
            AW. Unpublished study prepared by ABC Labs, Inc.  106 p.

42153401    Baer, K. (1991) Chronic Toxicity of DPX-Z326-198 (Linuron) to Daphnia
            magna: Lab Project Number: MR-9118-001: 558-91. Unpublished  study
            prepared by E. I. du Pont de Nemours and Co. 429 p.

42159601    Atkins, R.; Kesterson, A. (1991) Aerobic Metabolism of Carbon 14-Siduron in
            Silt Loam Soil: Lab Project Number: AMR-1791-90:  1621-90-100-03-28D-4:
            1397. Unpublished study prepared by E.I. du Pont de Nemours and Co. 62 p.

42270301    Cohle, P.; Muckerman,  M. (1992) Early Life-Stage Toxicity of Thidiazuron to
            Fathead Minnows (Pimephales promelas) in a Flow-through System: Lab Project
            Number: 39113: 506/AW. Unpublished study prepared by ABC Laboratories,
            Inc. 86 p.
                                        43

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42312901    Ward, T.; Boeri, R. (1992) Early Life Stage Toxicity of DPX-14740-166
            (Diuron) to the Sheepshead Minnow, Cyprinodon variegatus: Lab Project
            Number: 866-91. Unpublished study prepared by Resource Analysts, Inc. 513 p.

42498006    Machado, M. (1992) Fluometuron: Acute Toxicity to Mysid Shrimp (Mysidopsis
            bahia) Under Flow-Through Conditions: Lab Project Number: 92-6-4301:
            1781.0292.6297.515. Unpublished study prepared by Springborn Laboratories
            Inc. 63 p.

42500600    Du Pont (1992) Submission of toxicity data to support DPX-14740-166
            registration. Transmittal of 1  study.

42535801    Silvoy, J. (1992) Terrestrial Field Dissipation of LX1100-03 (Siduron) Applied
            to Cool-Season Turf and Bare Ground in California and Wisconsin: Lab Project
            Number: 1792-90: 270W:  1641-89-100-03-24A-0. Unpublished study prepared
            by PTRL-WEST and Research for Hire.  169 p.

42568501    Lintott, D. (1992) Fluometuron: Acute Toxicity to the Mysid, Mysidopsis bahia,
            under Flow-through Test Conditions: Lab Project Number: J9201001C.
            Unpublished study prepared by Toxikon Environmental Sciences. 24 p.

42627001    Frame, S. (1993) Repeated Dose Dermal Toxicity: 21-day Study with IN Z1318-
            70 (Siduron) in Male Rabbits: Lab Project Number: 8816-001: 108-91  SUPP 1.
            Unpublished study prepared by Dupont's Haskell Laboratory for Toxicology and
            Industrial Medicine. 28 p.

43075201    Schupner, J. (1994) Thidiazuron:  Chronic Toxicity of Thidiazuron to Daphnia
            magna Under Flow-through Test Conditions: W-81 Addendum #1: Lab Project
            Number: 39114: 507-AW. Unpublished study prepared by Nor-Am Chemical
            Co. 33 p.

43324501    Davis, J.; Kernaghan, N. (1994) Siduron Technical:  Acute Toxicity to Rainbow
            Trout, Oncorhynchus mykiss, Under Static Test Conditions: Lab Project
            Number: J9403003E. Unpublished study prepared by Toxikon Environmental
            Sciences. 55 p.

43324502    Kernaghan, N.; Davis, J. (1994) Siduron Technical:  Acute Toxicity to the Water
            Flea, Daphnia magna, Under Static Test Conditions: Lab Project Number:
            J9403003F. Unpublished study prepared by Toxikon Environmental Sciences.
            54 p.

43327902    Davis, J.; Kernaghan, N. (1994) Siduron Technical:  Acute Toxicity to the
            Sheepshead Minnow, Cyprinodon variegatus, under Static Test Conditions: Lab
            Project Number: J9403003G. Unpublished study prepared by Toxikon
            Environmental Sciences. 49 p.
                                        44

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43351501    Glaza, S. (1994) Dermal Sensitization Study of Siduron Technical in Guinea
            Pigs: Closed Patch Technique: Final Report: Lab Project Number: 40501303:
            HWI/40501303. Unpublished study prepared by Hazleton Wisconsin, Inc. 31 p.

43385401    Davis, J.; Kernaghan, N. (1994) Siduron Technical: Acute Toxicity to Embryos
            and Larvae of the Eastern Oyster, Crassostrea virginica, Under Static Test
            Conditions: Lab Project Number: J9403003I. Unpublished study prepared by
            Toxikon Environmental Sciences. 55 p.

43385402    Schwab, D. (1994) Evaluating the Effects of Siduron on the Germination,
            Emergence, and Vegetative Vigor of Non-target Terrestrial Plants: Lab Project
            Number: 41542. Unpublished study prepared by ABC Labs, Inc. 123 p.

43587001    Clark, A. (1995) Product Chemistry for Siduron, Series 63: Physical and
            Chemical Characteristics: Lab Project Number: 3660-03. Unpublished study
            prepared by Midwest Research Institute. 40 p.

43846701    Atkins, R. (1995) Aerobic Soil Metabolism of Methylcyclohexyl- (carbon 14)-
            Siduron in Sandy Loam: Lab Project Number: 840: 1851. Unpublished study
            prepared by PTRL Esat, Inc. 105 p.
43883301    Rodgers, M. (1995) Siduron: Bobwhite Quail Dietary Reproduction and
            Tolerance Studies: Lab Project Number: GWN 1: GWN 1/951478. Unpublished
            study prepared by Huntingdon Life Sciences Ltd. 252 p.

43996501    Brown, M.  (1996) Static, Acute, 48-Hour EC50 of DPX-Z326-198 (Linuron) to
            Daphnia magna: Lab Project Number: 10496: HLR 141-96: HA-95-019.
            Unpublished study prepared by DuPont's Haskell Lab for Toxicology and
            Industrial Medicine. 39 p.

43996502    Boeri, R.; Magazu, J.; Ward, T. (1996) Early Life Stage Toxicity of DPX-Z326-
            198 (Linuron) To the Sheepshead Minnow, Cyprinodon variegatus: Lab Project
            Number: 113-96: 10373: 815-DU. Unpublished study prepared by T.R. Wilbury
            Lab, Inc. 1032 p.
43996503    Boeri, R.; Magazu, J.; Ward, T. (1996) Chronic Toxicity of DPX-Z326-198
            (Linuron) To The Mysid, Mysidopsis bahia: Lab Project Number: 114-96:
            10373: 814-DU. Unpublished study prepared by T.R. Wilbury Labs, Inc. 821 p.

45868301    Mahabir, S.; Glover, S. (2003) Siduron Technical: Acute Toxicity to the Mysid
            Shrimp, Mysidopsis bahia, Under Static Test Conditions: Lab Project Number:
            02J0050B:  0104. Unpublished study prepared by Toxikon Corporation. 38 p.
            (OPPTS 850.1035}

46203503    Blankinship, A.; Palmer, S.; Kendall, T.; et. al. (2003) Thidiazuron: A 48-Hour
            Static Acute Toxicity Test with the Cladoceran (Daphnia magna): Final Report.
            Project Number: 149A/151, C032042. Unpublished study prepared by Wildlife
            International, Ltd. 40 p.
                                        45

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47081601    Bans, R.; Cohen, S. (2007) A Summary of Water Quality Monitoring Studies;
            Detections of Siduron in Ground Water and Surface Water. Project Number:
            06/40, 474047, EHL/RF/261/00. Unpublished study prepared by Environmental
            & Turf Services, Inc. 25 p.
                                        46

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Appendix E. List of Available Related Documents and Electronically Available Forms
Pesticide Registration Forms are available via the Agency's website at
http://www.epa. gov/opprdOOl/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 hard copy 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) 308-5551 or by
e-mail at Williams.nicolefyepa.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
8570-32
8570-34
8570-35
8570-36
8570-37
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
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)
http://www.epa.zov/opprd001/forms/8570-l.pdf

http://www. epa.zov/opprdOOl/foms/85 70-4. pdf

http://www.epa.zov/opprd001/forms/8570-5.pdf

http://www.epa.zov/opprd001/forms/8570-17.pdf

http://www. epa.zov/opprdOOl/forms/85 70-25.pdf

http://www.epa.zov/opprd001/forms/8570-27.pdf

http://www.epa.zov/opprd001/forms/8570-28.pdf

http://www.epa.zov/opprd001/forms/8570-30.pdf

http://www.epa.zov/opprd001/forms/8570-32.pdf

http://www. epa.zov/opppmsdl/PR Notices/pr98-5.pdf

http://www. epa.zov/opppmsdl/PR Notices/pr98-5.pdf

http://www.epa.zov/opppmsdl/PR Notices/pr98-l.pdf

http://www.epa.zov/opppmsdl/PR Notices/pr98-l.pdf

                                              47

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Pesticide Registration Kit

 http ://www. epa. gov/pesticides/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 §156, Labeling Requirements for Pesticides and Devices (PDF format)
f.      40 CFR § 158, Data Requirements for Registration (PDF format)
g.      50 F.R. 48833, Disclosure of Reviews of Pesticide Data (November 27, 1985)
                                          48

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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 22161-0002

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 at http:/Avww.nets.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 in 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.
                                          49

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