United States Prevention, Pesticides EPA 738-R­ 04-012 Environmental Protection and Toxic Substances September 2005 Agency (7508C) 

# Reregistration Eligibility Decision for Thidiazuron

List D
Case No. 4092

Approved by: Date:______________ Debra Edwards, Ph. D

. Director Special Review and Reregistration Division

### Table of Contents

Executive Summary
.............................................................................................................. ..................... iv
I. Introduction
............................................................................................................... .......................... 1 II. Chemical Overview
......................................................................................................... .................... 2 A. Regulatory History
......................................................................................................... ............ 2 B. Chemical Identification
.................................................................................................... .......... 2 C. Use Profile
................................................................................................................ ................... 3 D. Estimated Usage of Pesticide
................................................................................................ ..... 4 III. Summary of Thidiaz u ron Risk Assessment
................................................................................... ... 4 A. Human Health Risk Assessment
............................................................................................... 5 1. Toxicity of Thidiaz u ron ................................................................................................... .... 5 a. Toxicity Profile
......................................................................................................... 5 b. FQPA Safety Factor
................................................................................................. 6 c. Endocrine Effects
..................................................................................................... 6 d. Toxicological Endpoints for Risk Assessment
...................................................... 7 e. Cancer Classification
............................................................................................... 7 2. Dietary Exposure and Risk from Food and Water
........................................................... 8 a. Exposure Assumptions and Data
............................................................................ 8 b. Population Adjusted Dose (PAD)
............................................................................ 9 3. Residential and Other Non-Occupational Exposure
......................................................... 9 4. Aggregate Risk
............................................................................................................ .......... 9 5. Occupational Risk
........................................................................................................ ........ 9 a. Occupational Toxicity
............................................................................................ 10 b. Occupational Handler Exposure
........................................................................... 10 c. Occupational Handler Risk Summary
................................................................. 11 d. Occupational Post-application Risk
..................................................................... 11 6. Cumulative Assessment
.................................................................................................... . 12 7. Human Incident Data
....................................................................................................... .. 12 B. Environmental Risk Assessment
............................................................................................. 1 3 1. Environmental Exposure
................................................................................................... 1 3 a. Environmental Fate and Transport
...................................................................... 13 b. Aquatic Organism Exposure
................................................................................. 13 c. Terrestrial Organism Exposure
............................................................................ 14

(1) Birds
.................................................................................................................. ....... 15 (2) Mammals
............................................................................................................... .. 15 d. Non-target Terrestrial Plant Exposure
................................................................ 15 2. Environmental Effects (Toxicity)
...................................................................................... 15 a. Toxicity to Aquatic Organisms
............................................................................. 15

(1) Freshw ater and Estuarine/Marine Fish
............................................................... 15 (2) Freshw ater and Estuarine Invertebrates
............................................................. 16 b. Toxicity to Aquatic Plants
..................................................................................... 16c. Toxicity to Terrestrial Organisms
........................................................................ 17 (1) Birds
.................................................................................................................. ....... 17 (2) Mammals
............................................................................................................... .. 17 d. Toxicity to Non-target Insects
............................................................................... 18 e. Toxicity to Terrestrial Plants
................................................................................ 19 3. Ecological Risk Estimation (RQs)
.................................................................................... 20 a. Risk to Aquatic Organisms
.................................................................................... 20

(1) Fish and Aquatic Invertebrates
............................................................................ 20 b. Risk to Aquatic Plants
............................................................................................ 21 c. Risk to Non-target Terrestrial Organisms
........................................................... 21

(1) Birds
.................................................................................................................. ....... 21 (2) Mammals
................................................................................................................ . 22 d. Risk to Non-target Insects
..................................................................................... 23 e. Risk to Non-ta rget Terrestrial Plants
................................................................... 23 4. Ecological Incidents
...................................................................................................... ...... 24 5. Endangered Species Concerns
.......................................................................................... 24 a. Risk to Endangered Species
.................................................................................. 24 6. Risk Characteriz a tion
..................................................................................................... ... 25 IV. Risk Management, Reregistration and Tolerance Reassessment Decision
.................................. 26 A. Determination of Reregistration Eligibility
........................................................................... 26 B. Public Comments and Responses
............................................................................................ 26 C. Regulatory Position
........................................................................................................ .......... 27 1. Food Quality Protection Act Findings
.............................................................................. 27 a. A Risk Cup @ Determination
..................................................................................... 27 b. Determination of Safety to the U.S. Population Including Infants and Children
........................................................................................................... 27 c. Endocrine Disruptor Effects
................................................................................. 28 d. Cumulative Risks
.................................................................................................... 28 2. Tolerance Reassessment Summary
................................................................................... 29 a. Tolerances Currently Listed Under 40 CFR ' 180.403
......................................... 29 b. Codex Harmoniz ation
.......................................................................................... .. 30 D. Regulatory Rationale
....................................................................................................... ........ 30 1. Labeling Requirements
..................................................................................................... . 30 2. Other Labeling Requirements
........................................................................................... 31 3. Endangered Species Considerations
................................................................................. 31 4. Spray Drift Management
................................................................................................... 32 V. What Registrants Need to Do
................................................................................................ ........... 32 A. Manufacturing Use Products
................................................................................................. . 32 1. Additional Generic Data Requirements
........................................................................... 32 2. Labeling for Manufacturing-Use Products
...................................................................... 33 B. End-Use Products
........................................................................................................... .......... 33 1. Additional Product-Specific Data Requirements
............................................................ 33 2. Labeling for End-Use Products
......................................................................................... 33 C. Labeling Changes Summary Table
......................................................................................... 33
VI. Appendices
................................................................................................................ ......................... 39A. Use Patterns Subject to Reregistration for Thidiaz u ron (Case 4092)
..................................... 40 B. Table of Generic Data Requirements and Studies Used to Make the Reregistration Decision
................................................................................................................. ......................... 41 C. Technical Support Documents
................................................................................................ .... 49 D. Citations Considered to be Part of the Data Base Supporting the Reregistration Eligibility Decision (Bibliography) for Thidiaz u ron ................................................................. 51 E. Generic Data Call-In
........................................................................................................ ............ 62 F. Product Specific Data Call-In
............................................................................................... ....... 64 G. Batching
.................................................................................................................... ..................... 66 H. List of Registrants Sent this Data Call-In
.................................................................................. 68 I. List of Available Related Docume nts and Electronically Available Forms
............................ 70

### Thidiaz u ron Reregistration Eligibility Decision Team

Office of Pesticide Programs: Biological and Econom ic Analysis Assessm ent Mojm ir Mazur Sharlita Harris Nicole Zinn
Environm ental Fate and Effects Risk Assessm ent
W illiam Evans Alex Clem Jam e s Hetrick Edward Odenkirchen
Health Effects Risk Assessm ent
Paul Chin Jeff Dawson Toiya Goodlow Registration Support
Joanne Miller Risk Managem e nt
John W

. Pates, Jr. Tom Brennan Barbara Briscoe

i

### Glossary of Terms and Abbreviations

AGDCI Agricultural Data Call-In ai Active Ingredient aPAD Acute Population Adjusted Dose AR Anticipated Residue BCF Bioconcentration Factor CARES

------- CCA Com p arative Cholinesterase Assay CFR Code of Federal Regulations cPAD Chronic Population Adjusted Dose CSF Confidential Statem ent of Form ula CSFII USDA Continuing Surveys for Food Intake by Individuals DCI Data Call-In DEEM Dietary Exposure Evaluation Model DFR Dislodgeable Foliar Residue DNT Developm ental Neurotoxicity DW LOC Drinking W a ter Level of Com p arison. EC Em ulsifiable Concentrate Form ulation EC Engineering Control EDW C Estim ated Drinking W a ter Concentration EEC Estim ated Environm ental Concentration EPA Environm ental Protection Agency EUP End-Use Product FATE5

------- FDA Food and Drug Adm i nistration FIFRA Federal Insecticide, F ungicide, and Rodenticide Act FFDCA Federal Food, Drug, and Cosm etic Act FQPA Food Quality Protection Act FOB Functional Observation Battery G Granular Form ulation GENEEC Tier I Surface W a ter Com puter Model GLN Guideline Num b er HAFT Highest Average Field Trial IR Index Reservoir LC 50 Median Lethal Concentration. A statistically derived c oncentration of a substance that can be expected to cause death in 50% of test anim als. It is usually expressed as the weight of substance per weight or volum e of water, air or feed, e.g., m g /l, m g /kg or ppm

. LD 50 Median Lethal Dose. A statistically derived single dose that can be expected to cause death in 50% of the test anim als when adm i nistered by the route indicated (oral, derm al, inhalation). It is expressed as a weight of substance per unit weight of anim al, e.g., m g /kg. Lifeline

------ LOC Level of Concern LOD Lim it of Detection LOAEL Lowest Observed Adverse Effect Level MATC Maxim u m Acceptable Toxicant Concentration F g/g Microgram s Per Gram F g/L Microgram s Per Liter
m g /kg/day Milligram Per Kilogram Per Day
m g /L Milligram s Per Liter MOE Margin of Exposure MRID Master Record Identification (num ber). EPA' s system of recording and tracking studies subm itted.

iiMUP Manufacturing-Use Product NA Not Applicable NAW QA USGS National W a ter Quality Assessm ent NPDES National Pollutant Discharge Elim ination System NR Not Required NOAEL No Observed Adverse Effect Level OP Organophosphate OPP EPA Office of Pesticide Program s OPPTS EPA Office of Prevention, Pesticides and Toxic Substances PAD Population Adjusted Dose PCA Percent Crop Area PDP USDA Pesticide Data Program PHED Pesticide Handler' s Exposure Data PHI Preharvest Interval ppb Parts Per Billion PPE Personal Protective Equipm ent ppm Parts Per Million PRZM/ Tier II Surface W a ter Com puter Model EXAMS Q 1 * The Carcinogenic Potential of a Com pound, Quantified by the EPA' s Cancer Risk Model RAC Raw Agriculture Com m odity RED Reregistration Eligibility Decision REI Restricted Entry Interval RfD Reference Dose RQ Risk Quotient SCI-GROW Tier I Ground W a ter Com puter Model SAP Science Advisory Panel SF Safety Factor SLC Single Layer Clothing SLN Special Local Need (Registrations Under Section 24 8 ) of FIFRA) TCPSA 2,3,3-trichloroprop-2-ene sulfoni c acid ([chem ical nam e ] Metabolite) TGAI Technical Grade Active Ingredient TRR Total Radioactive Residue USDA United States Departm e nt of Agriculture USGS United States Geological Survey UF Uncertainty Factor UF db Database Uncertainty Factor UV Ultraviolet W PS W o rker Protection Standard

iiiExecutive Summary
This docum ent presents the Environm ental Protection Agency’s (hereafter the Agency or EPA) decision regarding the reregistration eligibility of the registered uses of thidiazuron [ 1

­ phenyl-3-(1,2,3-thidiazol-5-yl)urea]. The Agency m a de its reregistration eligibility determ ination based on its review of the required data and current guidelines for conducting acceptable studies to generate such data. The Agency has found that currently registered uses of thidiazuron are eligible for reregistration, provided that the changes specified in this docum ent are m a de to the label.
Thidiazuron is a m e m b er of the phenylurea class of herbicides and is used as a growth regulator only on cotton. The first registration was in 1982. Currently, there are 22 tolerances for thidiazuron. Dietary Risk from Food and W a ter An acute dietary assessm ent was not perform e d on thidiazuron because there were no effects observed in the available toxicology studies that could be attributable to a single exposure (dose). Chronic dietary risk estim ates for food and water are below the Agency’s level of
concern. The highest chronic exposure and risk estim ates were for children 1 to 2 years old. The chronic dietary risks are less than 100% of the chronic Population Adjusted Dose (cPAD) for all population subgroups. Therefore, no m itigation is warranted at this tim e for dietary exposure to thidiazuron. Occupational Risk To address occupational exposure, short-term inhalation, and interm ediate-term inhalation risks were assessed. MOEs were not calculated for derm al exposures, since no hazard concern was identified for exposures via the derm al route. For handlers, in all scenarios considered, risks were not of concern (MOEs ranged from 150 to 1,300,000 at baseline protection). Therefore, no
m itigation is warranted at this tim e for occupational risk to thidiazuron.
Residential Risk
There are no residential uses of thidiazuron. Therefore, residential exposures are not expected and a residential exposure assessm ent was not conducted. Aggregate Risk An acute dietary assessm ent was not perform e d on thidiazuron because there were no effects observed in the available toxicology studies that could be attributable to a single exposure (dose). Therefore, no m itigation is warranted at this tim e for acute aggregate risk to thidiazuron. A chronic aggregate risk assessm ent was conducted for thidiazuron. The chronic aggregate risk looked at the com b ined risk from dietary e xposure (food and drinking water pathways), since

ivthere are no residential uses. Chronic risks from food exposures were below the Agency' s level of concern. Therefore, no m itigation is warranted at this tim e for aggregate risk to thidiazuron. Ecological Risk Non-target terrestrial and sem i -aquatic plants are at potential direct risk from thidiazuron
use. Dicots are sensitive to thidiazuron, but m onocots do not appear to be affected at expected environm ental concentrations. Aquatic plants do not appear to be at risk. However, if terrestrial non-target plants com e in contact with thidiazuron, these plants m a y be killed or dam a ged enough to prevent the plant from reproducing or successfully com p eting with other plants for
resources. For m a m m a ls, acute risks did not exceed levels of concern, but there is a potential for chronic risk when m a xim u m (high-end) EECs are assum e d. For birds, acute risk quotients did not exceed levels of concern. Chronic risks to birds cannot be estim ated due to absence of data; however such data will be required as a f o llow-up to this RED. To help m itigate environm ental risks, specific language clarifying allowable use rates and conditions shall be required. Endangered Species The Agency’s screening level risk assessm ent for listed species indicates that thidiazuron exceeds the endangered species levels of concern for endangered and threatened terrestrial and
sem i -aquatic dicots, and exceeds chronic levels of concern for certain m a m m a ls. Next Steps The Agency is issuing this RED docum ent f o r thidiazuron as announced in a Notice of Availability published in the Federal Register. In the near future, EPA will issue a generic DCI for additional data necessary to confirm the conclusions of this RED for the active ingredient thidiazuron. EPA will also issue a product specific DCI for data necessary to com p lete product reregistration for products containing thidiazuron.

vI. Introduction The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) was am ended in 1988 to accelerate the reregistration of products with active ingredients registered prior to Novem b er 1, 1984. The am ended Act calls for the developm ent and subm ission of data to support the reregistration of an active ingredient, as well as a review of all subm itted data by the U.S. Environm ental 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 determ ine the need for additional data on health and environm ental effects; and to determ ine whether or not the pesticide m eets the "no unreasonable adverse effects" criteria of FIFRA. On August 3, 1996, the Food Quality Protection Act of 1996 (FQPA) was signed into law. This Act am ends FIFRA and the Federal Food Drug and Cosm etic Act (FFDCA) to require
reassessm ent of all existing tolerances for pesticid es in food. FQPA also requires EPA to review all tolerances in effect on August 2, 1996, by August 3, 2006. In reassessing these tolerances, the Agency m u st consider, am ong other things, aggregate risks from non-occupational sources of pesticide exposure, whether there is increased susceptibility to infants and children, and the
cum u lative effects of pesticides with a com m on m echanism of toxicity. W h en a safety finding has been m a de that aggregate risks are not of concern and the Agency concludes that there is a reasonable certainty of no harm from aggregate exposure, the tolerances are considered reassessed. EPA decided that, for those chem i cals that have tolerances and are undergoing reregistration, tolerance reassessm ent will be accom p lished through the reregistration process.
As m e ntioned above, FQPA requires EPA to consider "available inform ation" concerning the cum u lative effects of a particular pesticide' s residues and "other substances that have a
com m on m echanism of toxicity" when considering whether to establish, m odify, or revoke a tolerance. Potential cum u lative ef f ects of chem icals with a com m on m echanism of toxicity are considered because low-level exposures to m u ltiple chem icals causing a com m on toxic effect by
a com m on m echanism could lead to the sam e adverse health effect as would a higher level of exposure to any one of these individual chem icals. For inform ation regarding EPA = s efforts to determ ine which chem icals have a com m on m echanism of toxicity and to evaluate the
cum u lative effects of such chem icals, see the policy statem ents released by the EPA = s Offi ce of Pesticide Program s concerning com m on m echanism determ inations and procedures for
cum u lating effects from substances found to have a com m on m e chanism on EPA = s website at http://epa.gov/pesticides/cum ulative/ .] Unlike other pesticides for which EPA has considered cum u lative risk based on a com m on m echanism of toxicity, EPA has not m a de a com m on m echanism of toxicity finding for thidiazuron. The Agency has found no inform ation indicating thidiazuron shares a com m on m echanism of toxicity with other substances. Thidiazuron does not appear to produce a toxic
m e tabolite produced by other substances. Therefore, for the purposes of tolerance reassessm ent and a decision on reregistration eligibility, EPA has assum e d that thidiazuron does not share a

1com m on m echanism of toxicity with other com pounds. In the future, if additional inform ation suggests thidiazuron shares a com m on m echanism of toxicity with other com pounds, additional testing m a y be required and a cum u lative assessm ent m a y be necessary.
This docum ent presents EPA = s revised hum an health and ecological risk assessm ents and the reregistration eligibility decision for thidiazuron. The docum ent consists of six sections. Section I contains the regulatory fram ework for reregistration/tolerance reassessm ent. Section II provides a profile of the use and usage of the chem ical. Section III gives an overview of the revised hum an health and environm ental effects risk assessm ents based on data, public
com m e nts, and other inform ation received in response to the prelim inary risk assessm ents. Section IV presents the Agency = s reregistration eligibility and risk m a nagem e nt decisions. Section V sum m a rizes label changes necessary to im plem ent the risk m itigation m easures outlined in Section IV. Finally, the Appendices list related inform ation and supporting docum ents. The prelim inary and revised risk assessm ents for thidiazuron are available in the Public Docket, under docket num ber(s) OPP-2004-0382 and on the Agency = s web page, http://www.epa.gov/edockets.

II. Chemical Overview
A. Regulatory History Thidiazuron has been registered for use as a pre-harvest cotton defoliant or growth regulator. It rem oves green leaves and im m a ture fruiting structures, which contribute to cotton staining. Currently, there are eighteen active pr oducts containing thidiazuron (one technical product) registered under Section 3 of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).

B. Chemical Identification
Technical Thidiaz u ron
O S H H N C N N

N
Com m on Nam e : Thidiazuron
Trade Nam e : Dropp 7
Chem ical Nam e : 1-phenyl-3-(1,2,3-thidiazol-5-yl)urea
Chem ical Fam ily: Phenylurea herbicide

2Case Num b er: 4092 CAS Registry Num b er: 51707-55-2
OPP Chem ical Code: 120301 Moleculer weight: 220.25

Em pirical Form ula: C 9 H 8 N 4 OS
Basic Manufacturers: Bayer CropScience LP
C. Use Profile The following is inform ation on the currently registered uses including an overview of use sites and application m e thods. A detailed table of the uses of thidiazuron eligible for reregistration is contained in Appendix A. Type of Pesticide: Herbicide Target organism (s): N/A
Mode of action: Used as a defoliant or growth regulator by rem oving green leaves and im m a ture fruiting structures, which contribute to cotton staining.
Use Sites: Cotton (only)
Food uses: Tolerances have been established for cottonseed, m ilk, eggs, m e at and m eat by-products of cattle, goat, hog, horse, and sheep because livestock and poultry feed on cottonseed and other by-products that m a y be treated with thidiazuron.
Non-Food & Residential Uses: N/A
Public Health Uses: N/A
Use Classification: General Use
Form ulation Types: Thidiazuron registered form ulations include wettable powders (W P) (50 percent active ingredient), soluble concentrates (SC) (12 percent active ingredient), and em ulsifiable concentrates (EC) (8.4-50 percent active ingredient).

3Application Methods: Thidiazuron can be applied with aerial or ground equipm ent, such as groundboom sprayers. Application Rates: The m a xim u m single application rate on labels when thidiazuron is the sole active ingredient is 0.2 lb. a.i. (active ingredient)/A on cotton. The m a xim u m seasonal rate is 0.3 lb. a.i./A. (A m a xim u m of two 0.1-0.2 lb. a.i./acre applications m a y be applied to m a ture cotton plants, not exceeding a total rate of 0.3 lb. a.i./A/season (0.337 kg a.i./ha/season)). Application Tim i ng: Applications of thidiazuron to cotton are m a de prior to harvesting. The m i nim u m pre-harvest interval (PHI) is 5 days and the Re-entry interval (REI) is 24 hours.

D. Estimated Usage of Pesticide The predom inant usage is in the m a jor cotton producing areas of the Mid-South, Southeast, and W e stern United States. Approxim a tely 30% of the annual U.S. cotton crop is treated with thidiazuron.

III. Summary of Thidiaz u ron Risk Assessment The following is a sum m a ry of EPA = s hum an health and ecological risk findings and conclusions for thidiazuron as presented fully in the docum ents “Thidiazuron: Revised HED Chapter of the Reregistration Eligibility Decisi on Docum e nt (RED)” written by T. Goodlow, B. Chin, and J. Dawson and “Environm ental Fate and Effects Division Revised Risk Assessm ent f o r the Reregistration Eligibility Decision of Thidiazuron” written by W

. Evans, A. Clem , J. Hetrick and E. Odenkirchen. The purpose of this section is to sum m a rize the key features and findings of the risk
assessm ent in order to help the reader better understand the risk m a nagem e nt decisions reached by the Agency. W h ile the risk assessm ents and related addenda are not included in the docum ent, they are available in the public docket (docket num ber OPP-2004-0382) and m a y also be accessed on the Agency’s website at http://www.epa.gov/pesticides/reregistration/status.htm

.

4A. Human Health Risk Assessment EPA released its prelim inary risk assessm ents for thidiazuron for public com m e nt on May 11, 2005 (Phase 3 of the public participation process). In response to com m e nts received, the risk assessm ents were updated and refined.
1. Toxicity of Thidiaz u ron Further details on the toxicity of thidiazuron can be found in the revised hum an health risk assessm ent, dated August 31, 2005, as listed in the technical support docum ents cited in Appendix C.

a. Toxicity Profile The available toxicity data indicate the acute oral, derm al, inhalation, and prim ary eye and derm al irritation toxicity of thidiazuron to be in toxicity categories III and IV. Thidiazuron is not a derm al sensitizer or a skin irritant. The acute toxicity of thidiazuron is listed in Table 1. Both subchronic and chronic toxicity studies in rats show that thidiazuron causes decreased body weight gains and food consum pti on. In addition, chronic toxicity studies showed bilateral vesicle atrophy in rats, and dilated tubules of epididym is in m i ce. In the subchronic toxicity study, sm all sem i nal vesicles a nd prostate were also reported. The data from the developm ental toxicity studies in rats and rabbits and of the 2-generation reproduction study indicated no increase in susceptibility of fetuses and pups to the in utero and/or postnatal exposure to thidiazuron. No neurotoxicity was reported in any of the st udies. Carcinogenicity studies in both rats and m i ce produced no treatm e nt-related increase in tum o r incidence. The standard battery of genotoxicity tests was negative. Therefore, thidi azuron has been classified as “not likely to be carcinogenic to hum ans.”

5Table 1. Acute Toxicity Data for Thidiaz u ron Guideline No./ Study Type MRID Number Results Toxicity Category
(870.1100) Acute Oral Toxicity- Rat 46121501 LD 50 > 2 g/kg III

(870.1200) Acute Derm al Toxicity- Rat 46121502 LD 50 > 5 g/kg 2000m g/kg IV
(870.1300) Acute Inhalation Toxicity- Rat 46121503 LC 50 > 3.48 m g /L IV

(870.2400) Acute Eye Irritation- Rabbit 42099601 Irritation clearing in 48 hours IV
(870.2500) Acute Derm al Irritation- Rabbit 42099602 No derm al effects IV (870.2600) Skin Sensitization- Guinea Pig 46121504 Not a skin sensitizer N/A

b. FQPA Safety Factor The Federal Food Drug and Cosm etic Act (FFDCA) as am ended by the Food Quality Protection Act (FQPA) directs the Agency to use an additional tenfold (10X) safety factor to take into account potential pre- and post-natal toxicity and com p leteness of the data with respect to exposure and toxicity to infants and children. FFDCA authorizes the Agency to m odify the tenfold safety factor only if reliable data dem onstrate that the resulting level of exposure would be safe for infants and children. FQPA Special Safety Factor After evaluating hazard and exposure data for thidiazuron, EPA reduced the default 10X FQPA special safety factor to 1X. The toxicity database for thidiazuron includes acceptable developm ental and reproductive toxicity studies, and there is no evidence in the developm ental toxicity study of susceptibility following in utero exposure. Also, the Agency has a low level of concern and no residual uncertainties f o r the ef f ects seen in the developm ental toxicity studies after establishing toxicity endpoints and traditional uncertainty factors to be used in the risk
assessm ent. Therefore, the 10X FQPA special safety factor was reduced to 1X.

c. Endocrine Effects
W h en the appropriate screening and/or testing protocols being considered under the Agency’s EDSP have been developed, thidiazuron m a y be subject to additional screening and/or testing to better characterize effects related to possible endocrine disruption.

d. Toxicological Endpoints for Risk Assessment
6The toxicological doses and endpoints used in the hum an health risk assessm ent for thidiazuron are sum m a rized below in Table 2.
Table 2. Toxicity Endpoints for Human Health Risk Assessment for Thidiaz u ron Exposure Scenario Dose used in Risk Assessment

(mg/kg/day); Uncertainty Factors FQPA Safety Factor; Level of Concern for

Risk Assessment Study and Toxicological Effects (MRID)

Acute Dietary NOT APPLICABLE. A dose and endpoint were not identified for this population group because there were no effects observed in the available toxicology studies which could be attributable to a single exposure (dose). Chronic Dietary (All populations) NOAEL= 3.93
m g /kg/day UF =100 Chronic RfD = 0.0393
m g /kg/day FQPA SF = 1X cPAD = chronic RfD FQPA SF
= 0.0393 m g /kg/day Dog chronic toxicity study LOAEL =11.1 m g /kg/day based on increased incidence of anem ia, changes in hem a tological param e ters and m a rked hem o siderosis in liver and spleen. (MRID No. 00159344) Dermal, Short,

Intermediate and Long-Term Quantitation of derm al exposure to thidiazuron is not necessary because derm al absorption in rats was low (MRID 46261502) and no derm al or system ic toxicity is expected, based on studies with both rats and rabbits. Inhalation, Short-Term a (1-30 days) NOAEL= 25
m g /kg/day UF: 100 0.25 m g /kg/day (target MOE of 100) Developm ental Toxicity - Rabbit LOAEL = 125 m g /kg/day based on decreased body weight gains (decreased. 70% during GD 6-29) and food consum ption (decreased 19 during GD 6-8; 44% during GD 14­ 18). (MRID No. 46121507)
Cancer Thidiazuron is classified as “not likely to be carcinogenic to hum ans".

a Since an oral NOAEL was selected, an inhalation absorpti on factor of 100% (default valu e) was used in route-toroute extrapolation to correct for differences in exposure routes.

e. Cancer Classification Based on the weight of evidence and lack of evidence of carcinogenicity in both rats and
m i ce (no treatm e nt-related increase in tum o r incidences), thidiazuron is classified as “not likely to be carcinogenic to hum ans".

72. Dietary Exposure and Risk from Food and Water

a. Exposure Assumptions and Data The tier 1 unrefined chronic dietary exposure assum p tions and risk analysis for thidiazuron was conducted using the Dietary Exposure Evaluation Model (DEEM-FCID J , Version 2.02) and the Lifeline J Model Version 2.0, both of which use food consum ption data from the United States Departm e nt of Agriculture = s (USDA = s) Continuing Surveys of Food Intakes by Individuals (CSFII) from 1994-1996 and 1998. The assum p tions of these dietary exposure assessm ents were tolerance level residues and 100% crop treated, with the exception of
m eat, m eat byproducts, and fat tolerances. Existing m eat, m eat byproduct, and fat tolerance levels for rum i nant livestock were not used in the aggregate assessm ent because the m a gnitude of the residue study suggests higher residue values than the current tolerance level. Therefore, the Agency extrapolated from the existing m a gn itude of residue study to obtain reasonable high end estim ates of total thidiazuron residues in livestock com m odities. In order to account for possible degradates of concern for the drinking water pathway, the Agency m odeled four different scenarios us ing FIRST, Version 1.0 (surface water) and SCIGROW (groundwater), Version 2.3. Estim ated Environm ental Concentrations (EECs) from
m odeling showed negligible dif f e rences regardless of application tim ing (all at once or split in two) based on lack of thidiazuron degradation in soil. The estim ated annual average (chronic) surface water concentration for the parent and both photoproducts, photo-thidiazuron and 1­ cyano-3-phenylurea, was 1.0 ppb.
Estim ated ground water concentrations are based on the Screening Concentration in Ground W a ter (SCI-GROW ) (Ver. 2.3; Nov. 4, 2003) m odel, which is a Tier 1 assessm ent that provides a high-end estim ate. The SCI-GROW m odel generates a single EDW C value of pesticide concentration in ground water used for drinking water and provides a ground water screening concentration for use in determ ining potential risk to hum an health from drinking water contam inated with a pesticide. Further, this EDW C is used in assessm ents of both acute and chronic dietary risk. It is not unusual for the ground water EDW C to be significantly lower than that for the surface water. The value for the chronic groundwater concentration was estim ated to be 0.066 ppb. The m o st conservative estim ate was used to assess chronic risk and included thidiazuron and both photoproducts, photo- thidiazuron and 1-cyano-3-phenylurea. The water concentration estim ate used was 1.0 ppb. The dietary exposure analyses in this assessm ent for thidiazuron result in dietary risk estim ates for food and water that are below the Agency’s level of concern for chronic dietary exposure. For the chronic analyses, the highest exposure and risk estim ates were for children 1 to 2 years old. Using DEEM-FCIDTM, the chronic exposure for children 1 to 2 years old was 0.002867 m g /kg/day, which utilizes 7.3% of the chr onic Population-Adjusted Dose (cPAD) for thidiazuron. Using the Lifeline Model, the chronic exposure for children 1 to 2 years old was 0.00254 m g /kg/day, which also utilizes 6.5% of the cPAD for thidiazuron. The results of the

8chronic dietary analysis for food and water are below the Agency’s level of concern and are
sum m a rized below in Table 3.

Table 3. Result of Chronic Dietary Exposure and Risk Estimates for Thidiaz u ron- Food and Water

Population Subgroup PAD, mg/kg/day DEEM-FCID Lifeline Water Concentration Estimates (ppb) Exposure, mg/kg/day % PAD Exposure, mg/kg/day % P AD

Chronic Dietary Estimates U.S. Population 0.0393 0.000899 2.3 0.000832 2.1 1.0 Children 1-2 yrs 0.0393 0.002867 7.3 0.00254 6.5 1.0

b. Population Adjusted Dose (PAD) A population adjusted dose, or PAD, is the reference dose (RfD) adjusted for the FQPA safety factor. A risk estim ate that is less than 100% of the chronic PAD, the dose at which an individual could be exposed over the course of a lifetim e and no adverse health effects would be expected, does not exceed EPA = s level of concern.
3. Residential and Other Non-Occupational Exposure Thidiazuron is not registered for residential (hom e/garden) use, nor is it used in or around public buildings, schools or recreational areas where children m i ght be exposed. Thus, there was no residential assessm ent developed for thidiazuron.
4. Aggregate Risk Since there are no residential uses registered, the aggregate exposure assessm ent for thidiazuron considered exposures from food and drinking water only. A Tier 1 chronic dietary risk assessm ent was conducted, which resulted in risk estim ates for food and water that are below the Agency’s level of concern for all population subgroups (<8% of the cPAD).

5. Occupational Risk
W o rkers can be exposed to a pesticide through m i xing, loading, and/or applying a pesticide, or re-entering treated sites. Occupational risk is m easured by a Margin of Exposure (MOE) which determ ines how close the occupational exposure com e s to a No Observed Adverse Effect Level (NOAEL). In the case of thidiazuron, MOEs greater than 100 do not exceed the Agency = s level of concern. This MOE level of concern is derived from the standard safety f actors of 10X f o r intraspecies variability and 10X f o r interspecies variability. Occupational risk is assessed for exposure at the tim e of application (term e d A handler @ exposure) and for exposure following application, or post-application exposure. Application
9param e ters are generally defined by the physical nature of the form ulation (e.g., form ula and packaging), by the equipm ent required to deliver the chem ical to the use site, and by the application rate required to achieve an efficacious dose.
For m o re inform ation on the assum p tions and calculations of potential risk of thidiazuron to workers, see the Section 9.0 of, “Thidiazur on: Revised HED Chapter of the Reregistration Eligibility Decision Docum e nt (RED)” dated August 31, 2005.

a. Occupational Toxicity The toxicity endpoint used in the occupational risk assessm ent for thidiazuron was from an oral developm ental toxicity study in rabbits (MRID 46121507). The dose used in the risk
assessm ent was a NOAEL of 25 m g /kg/day for m a ternal toxicity based on abortions and decreased body weight gain and food consum pti on at the LOAEL of 125 m g /kg/day. Inhalation absorption was assum e d to be equivalent to oral absorption.

b. Occupational Handler Exposure Occupational handler risks from inhala tion were assessed for both short- and interm ediate-term durations of exposure. Occ upational handler risk from derm al exposure was not assessed because derm al absorption is low, and no derm al or system ic toxicity is expected from the derm al route. Chronic occupational risks were not assessed because exposure for m o re than 6 m onths is unlikely, since the cultivation and harvesting of cotton is a predom inately
m echanized process. The assessm ent of interm ediate-term risks provides an upper-bound
assessm ent of the potential risks. Occupational handler assessm ents are conducted using increasing levels of personal protective m easures. The Agency typically evaluates all exposures with m i nim a l protection and then considers additional protective m easures using a tiered approach (going from m i nim a l to
m a xim u m levels of protection) until risks f a ll below EPA’s level of concern. The lowest tier is represented by the baseline clothing scenario (i.e., single layer clothing, socks, shoes, and no respirator), f o llowed by increasing levels of risk m itigation such as personal protective equipm ent (PPE) and engineering controls (EC) if the MOEs indicate a potential risk concern at the baseline scenario. In the case of thidiazuron, MOEs for every occupational exposure scenario are above 100 at baseline PPE (long-sleeved shirt, long pants, socks, shoes, and no respirator) and therefore do not exceed the Agency’s level of concern. The assessm ent for thidiazuron as an active ingredient does not indicate a need for additional PPE, but the need for end-use product PPE will be assessed on a product-by-product basis.

c. Occupational Handler Risk Summary

10Based on the use patterns, 5 m a jor occupational handler exposure scenarios were identif ied as f o llows: Mixing/Loading: (1a) Liquids for Aerial; (1b) Liquids for Groundboom /Com m e rcial Applications; (1c) Liquids for Groundboom /Grower Applications; (2a) W e ttable Powders for Aerial; (2b) W e ttable Powders for Groundboom /Com m e rcial Applications; (2c) W e ttable Powders for Groundboom /Grower Applications; Applicator: (3) Aerial/Liquid Application; (4a) Groundboom Application/Com m e rcial; (4b) Groundboom Application/Grower; and Flaggers: (5) Flagging for Liquid Sprays.

Sum m a ry of Risk Estim ates for Handlers
Short- and interm ediate-term inhalation MOEs for occupational handler scenarios are greater than 100 at the baseline level of protection (i.e., long-sleeved shirt, long pants, shoes plus socks, and no respirator). MOEs range from 150 for m i xer/loaders (aerial) to >1 m illion for applying with groundboom

. Therefore, short- and interm ediate-term occupational risk is below EPA’s level of concern.
For m o re inform ation, see the Occupational Exposure/Risk Pathway (Section 9.0) in the Thidiazuron: Revised HED Chapter of the Reregistration Eligibility Decision Docum e nt (RED) dated August 31, 2005.

d. Occupational Post-application Risk EPA did not quantify occupational post-application risks to agricultural workers following application to cotton, because there were no derm al toxicological endpoints of concern identified, and because post-application inhalation exposure is expected to be negligible once sprays have dried. 6. Cumulative Assessment
Risks sum m a rized in this docum ent are those that result only from the use of thidiazuron.

11The Food Quality Protection Act (FQPA) requires that the Agency consider available inform ation concerning the cum u lative effects of a particular pesticide’s residues and other substances that have a com m on m echanism of toxicity. The reason for consideration of other substances is due to the possibility that low-level exposures to m u ltiple chem ical substances that
cause a com m on toxic effect by a com m on toxic m echanism could lead to the sam e adverse health effect as would a higher level of exposure to any of the substances individually. Unlike other pesticides for which EPA has followed a cum u lative risk approach based on a com m on m echanism of toxicity, EPA has not m a de a com m on m echanism of toxicity finding for thidiazuron and any other substances. Therefore, for the purposes of this action, EPA has
assum e d that thidiazuron does not share a com m on m echanism of toxicity with other
com pounds. For inform ation regarding EPA = s efforts to determ ine which chem icals have a
com m on m echanism of toxicity and to evaluate the cum u lative effects of such chem icals, see the policy statem ents released by EPA = s Office of Pesticide Program s concerning com m on m echanism determ inations and procedures for cum u lating effects from substances found to have
a com m on m echanism on EPA = s website at http://www.epa.gov/pesticides/cum ulative/

. 7. Human Incident Data In evaluating incidents to hum ans, the Agency reviewed reports from the National Poison Control Centers (PCC), the Agency = s Office of Pesticide Program = s Incident Data System (IDS), and the Calif ornia Pesticide Illness Surveillance Program

. The f o llowing databases have been consulted for the poisoning incident data on the active ingredient thidiazuron. Relatively few incidents of illness have been reported due to thidiazuron. Since 1992, OPP IDS has only reported 5 incidents as a result of thidiazuron exposure, which all show sim ilar sym p tom s such as skin rash, nausea, and weakness. However, no m e dical treatm e nt was required. The PCC database reported no incidents from 1993-1998; from 1999-2001, there was one report of a child exposed. However, there were no sym p tom s reported and the child was not seen at a health care facility. NIOSH SENSOR data from 1998-2002 reported a single thidiazuron exposure incident due to drift from an aerial application in 1998. There were no poisoning reports due to thidiazuron in Calif ornia from 1982- 2002, according to the California Departm e nt of Pesticide Regulation (CDPR). A dditionally, there were no incidents of poisoning or other hum an health effects related to thidiazuron found in scientific literature. Relatively few incidents of illness have been reported due to thidiazuron; as a result, no recom m e ndations based on incident occurrence are warranted.

12B. Environmental Risk Assessment
A sum m a ry of the Agency = s environm ental risk assessm ent f o r thidiazuron is presented below. Thidiazuron’s use as a cotton defoliant resulted in potential environm ental risks to nontarget plants (both terrestrial and sem i -aquatic dicots) and m a m m a ls (herbivores and insectivores) foraging on short grass and broadleaf forage, as well as foraging on sm all insects, when m a xim u m (high-end) EECs are assum e d. More detailed inform ation associated with the environm ental risk from the use of thidiazuron can be found in the Environm ental Fate and Ef f ects Division’s Revised Risk Assessm ent f o r the Reregistration Eligibility Decision of Thidiazuron for Use on Cotton, dated Septem ber 15, 2005. The com p lete environm ental risk
assessm ent is not included in this RED, but m a y be accessed in the OPP Public Docket (docket
num ber OPP-2004-0382) and on the Agency’s website at http://www.epa.gov/pesticides/reregistration/status.htm

. 1. Environmental Exposure

a. Environmental Fate and Transport
The environm ental fate database is sufficient to characterize the environm ental exposure associated with thidiazuron use. However, EPA intends to issue a data call-in (DCI) f o llowing the issuance of this RED to require subm ission of additional data for the parent com pound and potential degradates (photodegradates) as well as spray drift data to address areas of uncertainty. These data are expected to confirm the conclusions of this environm ental risk assessm ent. In soil, thidiazuron is persistent, as evidenced by laboratory and field half-lives of approxim a tely one year. It has interm ediate soil adsorption coefficients. Such persistence and interm ediate m obility would allow som e year-to-year accum u lation and the potential for runoff f r om application sites to occur. Based on its solubility, vapor pressure, and other laboratory evidence, thidiazuron is non-volatile. In addition, based on its relatively low octanol/water partitioning coef f i cient, thidiazuron is not expected to bioconcentrate.
W h en thidiazuron reaches surface water, photolysis is expected to be the m a jor route of transform a tion; other degradative processes are essentially negligible by com p arison. Aqueous photolysis rapidly yields two photoproducts. One of the photodegradates (photothidiazuron) is a structural isom er of the parent, while the other has a substantially altered chem ical structure (1­ cyano-3-phenylurea). Only photothidiazuron was in cluded in the risk assessm ent. Ground water is not im pacted by these degradates because all field studies show that the parent is long-lived in soil (half-lives of the order of one yea r) with only m i nim a l evidence of photolysis.

b. Aquatic Organism Exposure For exposure to aquatic fish and invertebrates, EPA considers surface water only, since
m o st aquatic organism s are not found in ground water. Surface water m odels are used to estim ate exposure to freshwater aquatic anim als. Available m onitoring data are generally not

13from studies targeted on sm all water bodies and prim ary stream s, where m a ny aquatic anim als are found. The Agency used m odeling to derive estim ated environm ental concentrations (EECs) for thidiazuron and its degradate, photothidiazuron. The m odeling results used in risk calculations f o r thidiazuron are detailed in the EFED chapter. Unlike the drinking water assessm ent described in the hum an health risk assessm ent section of this docum ent, the ecological water resource assessm ent does not include the Index Reservoir (IR) and Percent-Crop Area (PCA) fact or refinem e nts. The IR and PCA factors represent a drinking water reservoir, not the variety of aquatic habitats, such as ponds adjacent to treated fields, relevant to a risk assessm ent for aquatic anim als. Therefore, the EEC values used to assess exposure to aquatic anim als are not the sam e as the values used to assess hum an dietary exposure from drinking water sources.
Thidiazuron is assum e d to be introduced to surface waters via runoff and spray drift. The Estim ated Environm ental Concentrations (EECs) used to determ ine the risk quotients (RQs) were estim ated by m odeling for surface water in a farm pond scenario. Based on the interm ediate range of its adsorption coefficients and the supplem ental field evidence, leaching should not be a m a jor route of dissipation. Resulting concentrations for the parent com pound plus photothidiazuron are below in Table 4.
Table 4. Estimated Environmental Concentrations (EECs) of Thidiaz u ron and Photothidiaz uron in Surface Water (ppb)

Peak 96-hour Average 21-day Average 60-day Average 90-Day Average

11 11 9.7 8.6 8.2

c. Terrestrial Organism Exposure The Agency assessed exposure to terrestrial organism s by first predicting the am ount of thidiazuron residues found on anim al food item s and then determ ining the am ount of pesticide
consum ed based on typical food consum ption by various species of birds and m a m m a ls. The
am ount of residues on anim al feed item s is based on the Fletcher nom ogram and the current
m a xim u m application rate for thidiazuron. Residues m a y be com p ared directly with dietary toxicity data or converted to an oral dose, as is the case for sm all m a m m a ls. Current labels allow
a m a xim u m single application of 0.2 lbs a.i./A (active ingredient/Acre) and up to 0.3 lbs a.i./A applications per season for a total seasonal m a xim u m rate of 0.3 lbs a.i./A. Accordingly, all thidiazuron labels allow two applications. The sum of these is a m a xim u m of 0.3 lbs a.i./A/yr (0.2 lb a.i./A for the first application and up to 0.1 lb a.i./A for the second application).

14(1) Birds For birds, toxicant concentrations (EECs) on food item s following m u ltiple applications were predicted based on Agency m odels. (2) Mammals The exposure route em phasis for m a m m a ls is on uptake through the diet via food item s
. The residue estim ates are based on a nom ogram that relates food item residues to a pesticide’s application rate. Residues m a y be com p ared directly with dietary toxicity data or converted to an oral dose, as is the case for sm all m a m m a ls. For m a m m a ls, the residue concentration is converted to daily oral dose based on fractions of body weight consum ed daily, as estim ated through m a m m a lian allom e tric relationships.

d. Non-target Terrestrial Plant Exposure Terrestrial plants inhabiting dry and sem i -aquatic areas m a y be exposed to pesticides from runoff, spray drift, or volatilization. Volatilization was not included in the assessm ent. Sem i

aquatic areas are those low-lying wet areas that m a y be dry at certain tim es of the year. The Agency’s runoff exposure estim ate is characterized as "sheet runoff" (one treated acre to an adjacent acre) for dry areas, or as "channelized runoff".
2. Environmental Effects (Toxicity)

a. Toxicity to Aquatic Organisms (1) Freshw ater and Estuarine/Marine Fish An acute freshwater fish toxicity classi fication for thidiazuron cannot be definitively established because no m o rtality or signs of intoxication were observed at the highest concentration tested 19 and 32 m g /L. Thidiazuron can be considered practically non-toxic for risk assessm ent purposes. A chronic toxicity study was subm itted for fr eshwater fish early life-stage (fathead
m i nnow) for parent thidiazuron. The NOAEC of the parent was 5,700 F g/L based on hatchability, fry survival, and total survival (MRID 421320-02). A chronic full life cycle test was not subm itted f o r f r eshwater f i sh or m a rine/estuarine f i sh.

15(2) Freshw ater and Estuarine/Marine Invertebrates Acute freshwater invertebrate data for the parent thidiazuron resulted in an LC50 of 5,700 F g/L and a NOAEC of 1200 ug/L. Therefore, this LC50 value classifies the parent com pound as
m oderately toxic to freshwater invertebrates. Acute freshwater invertebrate studies on the m a jor degradates were also subm itted and showed LC50 > 12,000 ug/L.
Acute m a rine invertebrate studies show that the m y sid shrim p and the eastern oyster
em bryo/larvae LC50s are 3,240 and 5,384 F g/L, and NOAECs are 1400 and 1.06 ug/L, respectively. This classifies thidiazuron as m oderately toxic to m a rine acute invertebrates. No studies were subm itted for any of the m e tabolites. In addition, no invertebrate full-life-cycle toxicity studies were subm itted to the Agency. A chronic daphnid toxicity study showed a LOAEC of <100 F g/L based on length. Even though a definitive NOAEC could not be obtained, the 21-day EC10 was found to be 720 F g/L. No chronic data were subm itted f o r m a rine invertebrates.
b. Toxicity to Aquatic Plants Aquatic plant testing was conducted on the parent com pound thidiazuron. The EC50 was determ ined to be >24,000 F g/L for the vascular plant ( Lemna gibba ) based on frond count as the
m o st sensitive param e ter. The NOAEC and EC05 were determ ined to be 8,600 and 570 F g/L, respectively. Non-vascular plant data were subm itted f o r the green alga, blue-green algae, and the m a rine diatom

. The m o st sensitive of these non-vascular plants was the m a rine diatom with an EC50 of 850 F g/L, a NOAEC of 110 F g/L, and EC05 of 56 F g/L. No data are currently available for the freshwater diatom

. Additional non-vascular plant data (green alga) was subm itted for three degradates and
m e tabolite. All these studies were considered as Tier 1 studies and classified as supplem ental because they were conducted for 3 days instead of 5 days as required by the Agency. Acute toxicity values for aquatic plants are shown in Table 5.

Table 5. Acute Toxicity of Thidiaz u ron to Aquatic Plants Species % a.i. EC50, ( F g/L) NOAEC/EC05 ( F g/L) a.i. MRID, Author, Year

Vascular Plant Duckweed ( L emna gibba) 99.5 >24,000 8600 / 570 46203506 Desjardins, D. et.al., 2003.

16Table 5. Acute Toxicity of Thidiaz u ron to Aquatic Plants (continued) Species % a.i. EC50, ( F g/L) NOAEC/EC05 ( F g/L) a.i. MRID, Author, Year

Nonvascular Plants Green algae ( S

elenastrum capricornutum) 99.3 >150 150 45638221, Jenkins, 1998. a
Blue-green algae ( A nabaena flos-aquae) 99.5 6000 2800 / 1800 46203504, Desjardins, D. et.al., 2003. a
Marine diatom ( S

keletonema costatum) 99.5 860 110/56 46203505, Desjardins, D. et.al., 2003. Thidiazuron Photometabolite (AE F132347)
Nonvascular Plants Greeen Algae ( S

cenedesmus subspicatus) 97.4 980 220 / 310 46203510, Desjardins, D. et.al., 2003. a Thidiazuron Urea Metabolite (AE F132345)
Nonvascular Plants Greeen Algae ( S

cenedesmus subspicatus) 91 w/w ai 3400 1300 / 1200 46203517, Desjardins, D. et.al., 2003. a Thidiazuron Photodegradate (AE C421200)
Nonvascular Plants Green Algae ( S

cenedesmus subspicatus) 98.4 70000 49,000 / 53,000 46203513, Desjardins, D. et.al., 2003. a

a Since the study duration was for 3 days instead of 5, the study can only be classified as a Tier 1 study.

c. Toxicity to Terrestrial Organisms (1) Birds Thidiazuron is classified as practically non- toxic to birds and no sub-lethal effects or other treatm e nt related effects were observed in a ny of the studies. No avian chronic testing data was subm itted to the Agency for thidiazuron. (2) Mammals Thidiazuron is classified as a category III com pound (m oderately toxic) for m a m m a ls based on an acute oral LD 50 value of 2000 m g /kg-body weight. However, m i nim a l adverse effects (anem i a, blood related effects and decreased body weight) were dem onstrated in the

17m a m m a lian subchronic toxicity and pre-natal developm ental toxcicity studies. See Table 6 for endpoints.
Table 6. Summary of Subchronic and Chronic Toxicity Endpoints for Mammals Toxicity

Study Test Species % a.i. NOAEL/LOAEL (mg/kg-bw t) MRID
Subchronic 52-week Oral Toxicity Dog 98.8 3.93/11.1 00159344 Chronic (reproductive) Prenatal Developm ental Toxicity Rat 99.4 100/300 00077127
Prenatal Developm ental Toxicity Rabbit 99.5 25/125 46121507 2-generation Reproductive Rat 99.5 Parental = 35.4/108.5 Repro = 108.5/ND* Offspring = 35.4/108.5 46209601

*ND= Not Determined
The results from a 2-generation rat study were used to assess chronic risks to m a m m a ls. The NOAEL for both parental and offspring toxi city in this study was 400 ppm diet and the LOAEL for these endpoints was 1200 ppm diet. Table 7 discusses the data that support the chronic toxicity data used in assessing the risks to m a m m a ls. Table 7: Mammalian Developmental and Chronic Toxicity to Thidiaz u ron
Test Type % a.i. NOAEC (m g ai/kg-diet) LOAEC (m g ai/kg-diet) Effects MRID #, Author, Year

EPA PC Code: 120301 - Thidiazuron Technical SN 49537 2-generation reproductive (rat) 400 ppm (35.4/39.8 m g /kg/day [ M /F]) 1200 ppm (108.5/121.1
m g /kg/day [M/F]) Delayed sexual
m a turity, disrupted

estrous cycling 46209601

3-generation reproductive (rats) 100 200 ppm (10 m g /kg bw/da) 600 (30 m g /kbw/da) a Decreased F3 litter size at 200 ppm

. 429589-01, Rees, S.J., 1992. (Core-Supplem entary)

a Based on decrease epidermal sperm counts.
d. Toxicity to Non-Target Insects Acute contact toxicity studies to honeybees revealed contact LD 50 s of greater than 100 F g ai /bee for thidiazuron technical and greater than 98.1 F g ai /bee f o r the SC42 water m i scible suspension concentrate 500 g/L. In addition, a 72- hour acute oral toxicity test was conducted for the SC42 water m i scible suspension concentrate 500 g/L in accordance with OECD guidelines.
18This study resulted in an oral contact LD 50 greater than 197.8 F g ai/bee. These results classify thidiazuron as practically non-toxic to non-target insects. Based on thidiazuron’s use pattern,
m i nim a l risk is expected to non-target insects.

e. Toxicity to Terrestrial Plants Since thidiazuron is used as a defoliant on cotton to inhibit regrowth and rem oval of both
m a ture and juvenile leaves in cotton, non-target terrestrial plant data are required. Several nonguideline studies evaluating thidiazuron phytotoxicity were subm itted and two are sum m a rized below.
Com b ined tier I and II testing for seedling em ergence and vegetative vigor (MRID #s 459085-01 and 459215-01) for the SC42 form ulated product have been subm itted. The seedling
em ergence tests indicated negative growth responses to plant em ergence for onion and oat by
m o re than 25% at the m a xim u m single application label rate of 0.2 lb a.i./A. This would indicate that a need exists for tier II testing for these two m onocot species. All other tested species showed an EC 25 above the m a xim u m single application rate which m ean no further data are required for seedling em ergence for those species.
Sim ilar results were shown in vegetative vigor tests. Negative growth responses below the EC 25 level were indicated for all the m onocots at the m a xim u m single application rate. This indicates that tier II testing will need to be perf orm e d for these m onocot species. All of the dicot plants were tested at the tier II level with the exception of turnip and cabbage and since these plants are not am ong the m o st sensitive dicots tested, further testing will not be required. The results from these tests are shown in Table 8.
Table 8: Terrestrial Plant Toxicity Summary for Thidiaz u ron SC 42 Study Type Most sensitive Crop EC25 / NOEC or EC05 (lb ai/A) Least sensitive Crop / Active Ingredient EC25 / NOEC or EC05 (lb ai/A) Seedling Em ergence Monocot Onion & oat <0.1783 / <0.1783 Corn & wheat >0.1783 / 0.1783

Dicot Turnip 0.0152 / 0.0031 Tom a to >0.1783 / >0.1783 Vegetative Vigor Monocot Onion, corn, & oat >0.1783 / <0.1783 W h eat > 0.1783 / 0.1783

Dicot Lettuce 0.0011 / 0.00005 Turnip & cabbage >0.1783 / <0.1783

193. Ecological Risk Estimation (RQs) The Agency’s ecological risk assessm ent com p ares toxicity endpoints from ecological toxicity studies to EECs based on environm ental fate characteristics and pesticide use data. To evaluate the potential risk to non-target organism s from the use of thidiazuron products, the Agency calculates an RQ, which is the ratio of the EEC to the m o st sensitive toxicity endpoint values, such as the m e dian lethal dose (LD50) or the m e dian lethal concentration (LC50). These RQ values are then com p ared to the Agency’s levels of concern (LOCs), given in Table 9 , which indicate whether a pesticide, when used as directed, m a y have the potential to cause adverse effects on non-target organism s. W h en the RQ exceeds the LOC for a particular category (e.g., endangered species), the Agency presum es a potential risk of concern to that category. These potential risks of concern m a y be addressed by further refinem e nts of the risk
assessm ent or m itigation. Use, toxicity, fate, and exposure are considered when characterizing the risk, as well as the levels of certainty and uncertainty in the assessm ent. EPA f u rther characterizes ecological risk based on any reported incidents to non-target terrestrial or aquatic organism s in the field (e.g., fish or bird kills).
Table 9. EPA’s Levels of Concern and Associated Risk Presumptions.

Risk Presumption LOC Terrestrial

Animals LOC Aquatic Animals LOC Plants

Acute Risk - there is potential for acute risk; regulatory action
m a y be warranted in addition to restricted use classification. 0.5 0.5 1

Acute Restricted Use - there is potential for acute risk, but m a y be m itigated through restricted use classification. 0.2 0.1 N/A

Acute Endangered Species - endangered species m a y be adversely affected; regulatory action m a y be warranted. 0.1 0.05 1

Chronic Risk - there is potential for chronic risk; regulatory action m a y be warranted. 1 1 N/A

For a m o re detailed explanation of the ecological risks posed by the use of thidiazuron, refer to the “Environm ental Fate and Effects Division’s Revised Risk Assessm ent for the Reregistration Eligibility Decision of Thidiazuron for Use on Cotton”, dated Septem ber 15, 2005.

a. Risk to Aquatic Organisms (1) Fish and Aquatic Invertebrates
Acute risks to all freshwater and m a rine fish and invertebrates are below all levels of concern established by the Agency’s screening level assessm ent for thidiazuron. The acute risk quotients ranged from <0.0003 (m arine fish) to 0.002 (freshwater fish and estuarine

20invertebrates).
Chronic risks to all freshwater and m a rine fish and invertebrates are below all levels of concern established by the Agency’s screening level assessm ent for thidiazuron. Chronic risk quotients ranged from 0.002 (freshwater fish) to >0.1 (freshwater invertebrates). Although there
m a y be som e uncertainty with respect to chronic risk to freshwater and m a rine invertebrates because a definitive NOAEC value could not be obtained, it is possible to estim ate chronic risk based on a 21-day EC 10 value which was obtained in the chronic freshwater invertebrate study. The 21-day EC 10 value was 720 F g/L based on the length of the test organism s. Using this generated EC 10 value, the definitive 21-day RQ value of 0.015 is well below the chronic level of
concern.
b. Risk to Aquatic Plants An aquatic plant risk assessm ent for acute risk to non-target plants (non-endangered and endangered) was conducted with endpoints from the m o st sensitive aquatic plant. The acute risk quotient for non-target plants was determ ined by dividing the peak concentration of thidiazuron in surface water by the EC50 value for the m o st sensitive aquatic plant species. The acute endangered species risk quotient was determ ined by dividing the peak concentration of thidiazuron in surface water by the NOAEC. As a result, the acute risk quotients for the nonendangered and endangered species were well below all established levels of concern for aquatic plants. Aquatic plants do not appear to be at risk; however, sem i -aquatic dicots, not m onocots, are at potential direct and indirect risk. The Agency does not conduct chronic risk assessm ents for plants. Prelim inary data indicate that there m a y be potential aquatic plant risks from the photoproducts of thidiazuron. The Agency intends to call in additional data in order to assess the risk.

c. Risk to Non-target Terrestrial Organisms (1) Birds There are no exceedences for any acute, acute restricted use, endangered species, or chronic LOCs for birds. Acute RQs from two applications of thidiazuron (for a seasonal
m a xim u m of 0.3 lb a.i./A) range from less than 0.013 to 0.001. Avian chronic risks cannot be quantitatively evaluated at this tim e because chronic data were not subm itted. However, available data showing that chronic levels of concern for m a m m a ls are exceeded and that thidiazuron is persistent in the field suggest that there is also potential for chronic risk to birds should they be of equal or greater sensitivity than m a m m a ls.

21(2) Mammals Acute RQs are calculated for three separate weight classes of m a m m a ls (15, 35, and 1000 g), each presum ed to consum e four different kinds of food (grass, forage, insects, and seeds). Chronic
m a m m a lian RQs are calculated using the m o st sensitive NOAEC from the 2-generation rat study and the residue concentration expected on food item s from Hoerger and Kenaga (1972) as m odified by Fletcher et al. (1994) listed in the ecological risk assessm ent. There are no exceedences of any acute LOCs for m a m m a ls as all RQs were <0.03. Chronic RQs for m a m m a ls did exceed LOCs, with RQs ranging from 1.8 (15-g m a m m a l feeding on short grass) to 0.01 (1000-g m a m m a l feeding on large insects). Potential effects at predicted m a xim u m and m ean residues for single applications were also evaluated. No RQ exceeds the chronic level of concern when considering m ean predicted residues (See Table 10). Table 10. Mammalian Chronic Risk Quotient Calculations for Spray Applications (NOAEL = 35.4 m g /kg-bw/da)

Animal

Body Weight (g) % Body Weight Consumed Scenario Predicted Ma x i mum Residue Levels Predicted Mean Residue Levels
EEC (mg/kg-diet) Chronic RQ EEC (mg/kg-diet) Chronic RQ

15 95 Short grass 67 1.8 * 23.73 0.64 Broadleaf forage, sm all insects 37 1.0 * 12.33 0.33

Large insects 4.2 0.1 1.96 0.05
35 66 Short grass 67 1.2 * 23.73 0.44 Broadleaf forage, sm all insects 37 0.7 12.33 0.23

Large insects 4.2 0.08 1.96 0.04
1000 15 Short grass 67 0.3 23.73 0.10 Broadleaf forage, small ins ects 37 0.2 12.33 0.05

Large ins ects 4.2 0.02 1.96 0.01

* indicates an exceedence of Chronic Level of Concern (LOC).

22d. Risk to Non-Target Insects
Available data from a honeybee acute contact toxicity study indicated that technical thidiazuron and form ulated product are practically nontoxic to the honeybee. The two other nontarget insect OECD studies showed no significant effects at the highest m a xim u m single rate (0.2 lb ai/A); therefore there is little concern for non-target insects. Thidiazuron use on cotton is predicted to pose m i nim a l risk to non-target insects.

e. Risk to Non-target Terrestrial PlantsThidiazuron poses potential risks to terrestrial plants based on the results of a screeninglevel assessm ent. The risk quotients exceed the levels of concern for non-endangered and endangered plants adjacent to treated sites as well as plants inhabiting sem i –aquatic sites. This is especially true f o r dicots f o r both single and m u ltiple applications. The RQs resulting f r om single applications at the m a xim u m label rates range from 0.39 to 9.09 for non-endangered plants (Table 11) and up to as high as 52.63 for endangered plants (See Table 12). Tier I testing data for vegetative vigor indicated negative growth response (<25%) in one of the four m onocots (onion) and five of the six sp ecies of dicots that were tested. Accordingly, Tier II studies are required for all low dose herbicides with m a xim u m use rates of 0.5 lbs ai/A or less and any pesticide showing a negative response equal to or greater than 25% in Tier I tests. Recently subm itted data com b ined Tier I and II testing for seedling em ergence and vegetative vigor (MRID #s 45908501 and 45921501) for the SC42 form ulated product, which have indicated that a need exists for Tier II testing for both onion and oat. Currently, EPA does not perform chronic risk assessm ents for terrestrial and sem i -aquatic plants. Adverse effects in terrestrial plants from thidiazuron applied at current labeled rates are expected, particularly in dicots (not m onocots). As a result, if non-target plants com e in contact with thidiazuron, they m a y be killed or dam a ged enough to prevent the plant from reproducing or successfully com p eting with other plants for resources.
Table 11. Terrestrial Plant Risk Quotients for Single Applications

Plant Group(nonEndangered / Endangered) Type of Plant Study Type of Plant (m onocot / dicot) Most Sensitive EC 25 (Non-Endangered) or NOAEC / EC 05

(Endangered) Risk Quotient Range (Plants

Adjacent to Treated Sites) Risk Quotient Range (Plants in

Semi-Aquatic Areas) Non-endangered Seedling Em ergence Monocot <0.1783 >0.03 - >0.07 >0.17 - > 0.22 Dicot 0.0152 0.39 - 0.79 1.97 - 2.63* Vegetative Vigor Monocot >0.1783 <0.01 - <0.06 <0.01 - <0.06
Dicot 0.0011 1.82 - 9.09* 1.82 - 9.09*

* Exceeds terrestrial plant Levels of Concern (LOC) 4. Ecological Incidents

23There are no reports or incidents of wildlife poisonings associated with thidiazuron in the Ecological Incident Inform ation System (EIIS) data base.

5. Endangered Species Concerns The screening level ecological risk assessm ent results in a determ ination that use of thidiazuron will have no direct acute ef f ects on f r esh water or m a rine/estuarine f i sh and invertebrates, insects, aquatic plants, terrestrial and sem i -aquatic m onocots, avian species, and
m a m m a ls. However, the Agency’s level of concern for direct effects to endangered and threatened terrestrial and sem i -aquatic plants, and for direct chronic effects to m a m m a ls is exceeded for the use of thidiazuron on cotton. In addition, the Agency can not quantitatively predict potential chronic risks to birds; however, if avian species are as sensitive, or m o re sensitive than m a m m a ls, a potential ef f ect could be of concern f o r avian species. Further, potential indirect effects to any species depende nt upon a species that experiences effects from use of thidiazuron, can not be precluded based on the screening level ecological risk assessm ent.

a. Risk to Endangered Species The screening level risk assessm ent for listed species indicates that thidiazuron exceeds the endangered species LOCs for the following com b inations of analyzed uses and species: (1) use of thidiazuron on cotton indicates that the chronic LOC of 1.0 is exceeded for 15 g m a m m a ls foraging on short grass and broadleaf forage and sm all insects. Chronic m a m m a lian RQs range up to 1.8; and (2) use of thidiazuron on cotton resu lts in an exceedence of the LOC for terrestrial and sem i -aquatic plants. County-level location data for listed species (terrestrial plants and m a m m a ls) were
com p ared with county-level inform ation on crop production to identify coarse overlaps of listed species with the proposed labeled use areas of thidaizuron. More inform ation on the num ber of species at potential risk can be found in the E nvironm ental Fate and Effects Division Revised Risk Assessm ent for the Reregistration Eligibility Decision of Thidiazuron for Use on Cotton, dated Septem ber 15, 2005. In addition to these potential direct effects, there m a y be potential for indirect effects to taxa of listed that are dependent upon a taxa that m a y experience effects from the use of this pesticide. Potential risks to endangered species identif ied in the Environm ental Fate and Ecological Risk Assessm ent and reflected in this RED for thidiazuron are based solely on EPA' s screening level ecological risk assessm ent and do not constitute "m ay effect" findings under the Endangered Species Act.

Table 12: Acute Endangered Terrestrial Plant Risk Quotient Calculations For Single Spray Applications of thidiaz u ron

24Scenario Toxicity Threshold, NOEC or EC05 (lb ai/ac) Plants Adjacent to Treated Sites Plants in Semi-aquatic Areas
Total Drift

(lb ai/ac) Total Loading (Sheet runoff + Drift) (lb ai/ac) RQ a Total Drift (lb ai/ac) Total Loading (Channel runof f + Drift) (lb ai/ac) RQ a

Cotton - Ground Applications (0.2 lbs ai/ac/app)

Seed Em ergence Monocot 0.1783 N/A 0.006 0.03 N/A 0.04 0.22
Dicot 0.0111 N/A 0.006 0.54 N/A 0.04 3.60*
Vegetative Vigor Monocot 0.1783 0.002 N/A 0.01 0.002 N/A 0.01
Dicot 0.00019 0.002 N/A 10.53* 0.002 N/A 10.53* Cotton - Aerial Applications (0.2 lbs ai/ac/app)

Seed Em ergence Monocot 0.1783 N/A 0.012 0.07 N/A 0.03 0.17
Dicot 0.0111 N/A 0.012 1.08* N/A 0.03 2.70*
Vegetative Vigor Monocot 0.1783 0.01 N/A 0.06 0.01 N/A 0.06
Dicot 0.00019 0.01 N/A 52.63* 0.01 N/A 52.63*

a Indicates acute risk to endangered plants.
6. Risk Characteriz a tion
Thidiazuron has a lim ited use pattern. It is used exclusively as a cotton defoliant to facilitate the uniform rem oval of both m a ture and juvenile leaves prior to m achine harvesting. Thidiazuron is only applied during the cotton harvesting period, which is typically in late August and early Septem ber. All labels indicate that citrus trees are particularly sensitive to thidiazuron. Product labels indicate that the areas potentially at di rect and/or indirect risk from the application of thidiazuron are the cotton agronom ic environm ents. In the case of m i xed products, the risk
assessm ent was conducted to focus on the fraction of the application rate contributed by thidiazuron (only) instead of the sum s of both active ingredients.
The m a in ecological risk concerns, based on toxicity testing with typical end-use products containing thidiazuron as the only active ingredient and the sm all am ount of data on three transform a tion products, are the following: (1) Non-target terrestrial and sem i -aquatic dicots (not m onocots) are at potential direct risks, whereas aquatic plants do not appear to be at risk. If non-target plants com e into contact with thidiazuron, these plants m a y be killed or dam a ged enough to prevent the plant from reproducing or successfully com p eting with other plants for resources. (2) Mam m a ls are at potential chronic risk, but not acute risk. (3) Potential acute risks to birds are below all levels of concern. However, potential chronic risk to birds cannot be determ ined, due to the absence of chronic data.

25The risk assessm ent for terrestrial plants was based on RQs calculated from toxicity studies using a typically form ulated end-use product (TEP) Thidiazuron SC42. However, it appears that no surfactants or other adjuvants were added to the product during the studies and all labels clearly state the addition of adjuvants has been shown to im prove the perform a nce. Therefore, the risk to terrestrial non-target plan ts m a y be greater than thidiazuron RQs indicate. Acute risk quotients for m a m m a ls did not exceed levels of concern (LOCs). However, chronic risk quotients for m a m m a ls did exceed LOCs for 15g m a m m a ls foraging in short grass, broadleaf forage, and on sm all and large insects when m a xim u m (high-end) EECs are assum e d. Potential effects at predicted m a xim u m and m ean residues for single applications were also evaluated. No RQ exceeds the chronic level of concern when considering m ean predicted residues.

IV. Risk Management, Reregistration, and Tolerance Reassessment Decision
A. Determination of Reregistration Eligibility Section 4(g)(2)(A) of FIFRA calls for the Ag ency to determ ine, after subm ission of relevant data concerning an active ingredient, whether or not products containing the active ingredient are eligible for reregistration. The Agency has previously identified and required the subm ission of the generic (i.e., active ingredient -specific) data to support reregistration of products containing thidiazuron as an active ingredient. The Agency has com p leted its review of these generic data, and has determ ined that the data are sufficient to support reregistration of all uses of thidiazuron. The Agency has com p leted its assessm ent of the dietary, occupational, and ecological risk associated with the use of pesticide products containing the active ingredient thidiazuron. Based on a review of these data and on public com m e nts on the Agency = s assessm ents for the active ingredient thidiazuron, the Agency has sufficient inform ation on the hum an health and ecological effects of thidiazuron to m a ke decisions as part of the tolerance reassessm ent process under FFDCA and reregistration process under FIFRA, as am ended by FQPA. The Agency has determ ined that thidiazuron containing products are eligible for reregistration provided that: (i) the risk m itigation m easures outlined in this docum ent are adopted; and (ii) label am endm ents are m a de to reflect these m easures.
B. Public Comments and Responses Through the Agency = s public participation process, EPA worked extensively with stakeholders and the public to reach the regulatory decisions for thidiazuron. During the public
com m e nt period on the risk assessm ents, which closed on July 11, 2005, the Agency received
com m e nts from four com m e ntors, Bayer CropScien ce, Siem er and Associates, and two private citizens. The com m e nts pertained to the im portance of particular uses and urged the Agency to consider how it regulated these com m odities. These com m e nts in their entirety are available in

26the public docket (OPP-2004-0382) at http://www.epa.gov/edockets. An individual response to these com m e nts is being prepared by EPA and will be m a de available in the public docket (OPP2004-0382). The RED and technical supporting docum ents for thidiazuron are available to the public through EPA = s electronic public docket and com m e nt system , EPA Dockets, under docket identification (ID) num ber OPP-2004-0382. The public m a y access EPA Dockets at http://www.epa.gov/edockets. In addition, the thidiazuron RED m a y be downloaded or viewed through the Agency = s website at http://www.epa.gov/pesticides/reregistration/status.htm

. C. Regulatory Position
1. Food Quality Protection Act Findings

a. A Risk Cup @ Determination As part of the FQPA tolerance reassessm ent process, EPA assessed the risks associated with this pesticide. EPA has determ ined that risk from dietary (food sources only) exposure to thidiazuron is within its own A risk cup. @ An aggregate assessm ent was conducted for exposures through food and drinking water. The Agency has determ ined that the hum an health risks from these com b ined exposures are within acceptable levels. In other words, EPA has concluded that the tolerances f o r thidiazuron m eet FQPA safety standards.

b. Determination of Safety to the U.S. Population Including Infants and Children The Agency has determ ined that the established tolerances for thidiazuron, with
am endm ents and changes as specified in this docum ent, m eet the safety standards under the FQPA am endm ents to section 408(b)(2)(D) of the FFDCA, and that there is a reasonable certainty no harm will result to the general population, infants and children or any subgroup from the use of thidiazuron. In reaching this conclusion, the Agency has considered all available inform ation on the toxicity, use practices and exposure scenarios, and the environm ental behavior of thidiazuron. As discussed in Chapter 3, the total acute dietary (food alone) risk was not assessed, since no appropriate acute endpoint wa s identified. Also, the chronic dietary risk estim ates for food (only) as well as food and water are both below the Agency’s level of
concern.
In determ ining whether or not infants and children are particularly susceptible to toxic effects from exposure to residues of thidiazuron, the Agency considered the com p leteness of the hazard database for developm ental and reproductive effects, the nature of the effects observed, and the possibility of increased dietary exposure due to the specific consum ption patterns of infants and children. The FQPA Safety Factor has been reduced to 1X for thidiazuron because: (1) there are no concerns and no indication of quantitative or qualitative increased susceptibility

27of rats or rabbits to in utero or postnatal exposure; and 2) the dietary (food and drinking water) exposure assessm ents will not underestim ate the potential exposures to infants and children.

c. Endocrine Disruptor Effects EPA is required under the FFDCA, as am ended by FQPA, to develop a screening program to determ ine whether certain substances (including all pesticide active and other ingredients)

A m a y have an effect in hum ans that is sim ilar to an effect produced by a naturally occurring estrogen, or other endocrine effects as the Adm i nistrator m a y designate. @ Following
recom m e ndations of its Endocrine Disruptor Screening and Testing Advisory Com m ittee (EDSTAC), EPA determ ined that there was a scientific basis for including, as part of the program , the androgen and thyroid horm one system s, in addition to the estrogen horm one system

. EPA also adopted EDSTAC = s recom m e ndation that EPA include evaluations of potential effects in wildlife. For pesticides, EPA will use FIFRA and, to the extent that effects in wildlife m a y help determ ine whether a substance m a y have an effect in hum ans, FFDCA authority to require the wildlife evaluations. As the science develops and resources allow, screening of additional horm one system s m a y be added to the Endocrine Disruptor Screening Program (EDSP). The available data on thidiazu ron indicated that there was no toxicologically significant evidence of endocrine disruption effects.

d. Cumulative Risks
Risks sum m a rized in this docum ent are those that result only from the use of thidiazuron. The Food Quality Protection Act (FQPA) requires that the Agency consider “available inform ation” concerning the cum u lative effects of a particular pesticide’s residues and “other substances that have a com m on m echanism of toxicity.” The reason for consideration of other substances is due to the possibility that low-level exposures to m u ltiple chem ical substances that
cause a com m on toxic effect by a com m on toxic m echanism could lead to the sam e adverse health effect as would a higher level of exposure to any of the substances individually. Unlike other pesticides for which EPA has followed a cum u lative risk approach based on a com m on m echanism of toxicity, EPA has not assum e d that thidiazuron shares a com m on m echanism of toxicity with other com pounds. For inform ation regarding EPA’s efforts to determ ine which chem icals have a com m on m echanism of toxicity and to evaluate the cum u lative effects of such chem icals, see the policy statem ents released by EPA’s Office of Pesticide Program s concerning
com m on m echanism determ inations and effects from substances found to have a com m on m echanism on EPA’s website at http://www.epa.gov/pesticides/cum ulative/.

282. Tolerance Reassessment Summary

a. Tolerances Currently Listed Under 40 CFR ' 180.403 The existing tolerances for residues of thidiazuron [1-phenyl-3-(1,2,3-thidiazol-5-yl)urea] are established under 40 CFR ' 180.403. Although additional data are required to confirm the existing tolerances in/on the f o llowing com m odities, the Agency has no dietary or drinking water risk concerns associated with these tolerances and considers them reassessed (see Table 13).
Table 13. Tolerance Reassessment Summary for Thidiaz u ron. Co mmo dity Current Tolerance

(ppm) Tolerance Reassessment (ppm) Co mment

Tolerances Listed Under 40 CFR ' 180.403(a) Cattle, fat 0.2 0.4 Proposed tolerances are considered reassessed and will be confirm e d upon the subm ission of additional data (see Regulatory Rationale). Cattle, m eat 0.2 0.4 Cattle, m eat byproducts 0.2 0.4
Cotton, undelinted seed 0.4 0.3 Available residue data from crop field trials provide sufficient inform ation to reduce the tolerance. Cotton, hulls 0.8 Revoke A processing study was perform ed for cottonseed m eal, oil, and hulls. Cottonseed hull residues are not expected to exceed the current
recom m e nded RAC tolerance of 0.3 ppm for cottonseed. Therefore, it is recom m e nded that the current 0.8 ppm tolerance for cottonseed hulls be revoked. Egg 0.1 Revoke Cottonseed m eal is a com m on feeding source for poultry. Thidiazuron residues in a cottonseed m eal processing study dem onstrated that tolerances are no longer required on eggs as there is no reasonable expectation of finite residues. Goat, fat 0.2 0.4 Proposed tolerances are considered reassessed and will be confirm e d upon the subm ission of additional data (see Regulatory Rationale). Goat, m eat 0.2 0.4 Goat, m eat byproducts 0.2 0.4
Hog, fat 0.2 0.4 Hog, m eat 0.2 0.4 Hog, m eat byproducts 0.2 0.4
Horse, fat 0.2 0.4 Horse, m eat 0.2 0.4

29Co mmo dity Current Tolerance

(ppm) Tolerance Reassessment (ppm) Co mment

Horse, m eat byproducts 0.2 0.4

Milk 0.05 0.05 Poultry, fat 0.2 Revoke Cottonseed m eal is a com m on feeding source for poultry. Thidiazuron residues in a cottonseed m eal processing study dem onstrated that tolerances are no longer required on poultry as there is no reasonable expectation of finite residues. Poultry, m eat 0.2 Revoke Poultry, m eat byproducts 0.2 Revoke

Sheep, fat 0.2 0.4 Proposed tolerances are considered reassessed and will be confirm e d upon the subm ission of additional data (see Regulatory Rationale). Sheep, m eat 0.2 0.4 Sheep, m eat byproducts 0.2 0.4
Tolerances To Be Proposed Under 40 CFR ' 180.403(a)(2) Cotton, gin byproduct Not established 24 Available residue data from crop field suggest that a tolerance of 24 ppm be established for cotton gin byproducts.
b. Codex Harmoniz ation
No CODEX m a xim u m residue levels (MRLs) have been established or proposed for thidiazuron. Therefore, issues of com p atibility between CODEX MRLs and U.S. tolerances do not exist.
D. Regulatory Rationale The Agency has determ ined that thidiazuron is eligible for reregistration, in com p liance with FIFRA, provided that: the risk m itigation m easures outlined in this docum ent are adopted and label am endm ents are m a de to reflect these m easures. Once an Endangered Species
assessm ent is com p leted, further changes to these registrations m a y be necessary as explained in section 3 below.
1. Labeling Requirements
The environm ental risks for thidiazuron were based on a screening-level assessm ent for both terrestrial and aquatic environm ents. The assessm ent was perform e d for geographic areas where the highest use rates and expected exposures are likely to occur. Results show som e concerns for acute risks to aquatic plants, terrestrial and wetland/riparian plants (which are not unexpected due to the herbicidal nature of the com pound), as well as som e chronic risks to
m a m m a ls when m a xim u m EECs are assum e d. In order to address the risks identified in this screening-level assessm ent, registrants will be required to decrease the m a xim u m labeled use

30rate from 0.2 lbs ai/acre to 0.125 lbs ai/acre under norm a l conditions of use, with an annual
m a xim u m application of 0.3 lbs ai/acre. However, under certain circum stances such as during periods of rank growth/high fertilizer conditions, extrem e weather conditions (such as extended periods of rain and/or low tem p eratures - 60 o to 65 o degree Fahrenheit), as well as on full-season cotton varieties, the higher rate (0.2 lbs ai/acre) m a y be used but total seasonal use m a y not exceed 0.3 lbs ai/acre.
2. Other Labeling Requirements In order to be eligible for reregistration, various use and safety inform ation will be included in the labeling of all end-use products containing thidiazuron. For the specific labeling statem ents and a list of outstanding data, refer to Section V of this RED docum ent.
3. Endangered Species Considerations The Agency has developed the Endangered Species Protection Program to identify pesticides whose use m a y cause adverse im pacts on endangered and threatened species, and to im plem ent m itigation m easures that address these im pacts. The Endangered Species Act requires federal agencies to ensure that their actions are not likely to jeopardize listed species or adversely m odify designated critical habitat. To analyze the potential of registered pesticide uses that m a y affect any particular species, EPA uses basic toxicity and exposure data developed for the REDs and considers ecological param e ters, pesticide use inform ation, geographic relationship between specific pesticide uses and species locations, and biological requirem e nts and behavioral aspects of the particular species. W h en conducted, this species-specific analysis will take into consideration any regulatory changes recom m e nded in this RED that are being im plem ented at that tim e.
A determ ination that there is a likelihood of potential im pact to a listed species m a y result in lim itations on use of the pesticide, other m easures to m itigate any potential im pact, or consultations with the Fish and W ildlif e Service and/or the National Marine Fisheries Service as necessary. If the Agency determ ines use of th idiazuron “m ay affect” listed species or their designated critical habitat, EPA will em ploy the pr ovisions in the Services regulations (50 CFR Part 402). Until that species specific analysis is com p leted, the risk m itigation m easures being im plem ented through this RED will reduce the likelihood that endangered and threatened species
m a y be exposed to thidiazuron at levels of concern. EPA is not requiring specific label language at the present tim e relative to threatened and endangered species. If in the future specific m easures are necessary for the protection of listed species, the Agency will im plem ent them through the Endangered Species Protection Program

.

314. Spray Drift Management The Agency has been working closely with stakeholders to develop im proved approaches f o r m itigating risks to hum an health and the environm ent f r om pesticide spray and dust drif t. As part of the reregistration process, we will continue to work with all interested parties on this im portant issue.
From its assessm ent of thidiazuron as sum m a rized in this docum ent, the Agency concludes that no drift m itigation m easures are needed for thidiazuron. In the future, thidiazuron product labels m a y need to be revised to include additional or different drift label statem ents.
V. What Registrants Need to Do The Agency has determ ined that thidiazuron is eligible f o r reregistration provided that: (i) label changes outlined in this docum ent are adopted as outlined in the Label Sum m a ry Table in Section C (Table 15) below. In the near future, the Agency intends to issue Data Call-In Notices (DCIs) requiring label am endm ents, product specific data and additional generic confirm a tory (technical grade) data. Generally, registrants will have 90 days from receipt of a DCI to com p lete and subm it response form s or request tim e extension and/or waiver requests with a full written justification. For product specific data, the registrant will have eight m onths to subm it data and am ended labels. For generic data, due dates can vary depending on the specific studies being required. Below are tables of additional generic data and label
am endm ents that the Agency intends to require.
A. Manufacturing Use Products
1. Additional Generic Data Requirements The generic data base supporting the reregistration of thidiazuron for the above eligible uses has been reviewed and determ ined to be substantially com p lete. However, the data listed below (Table 14) are necessary to conf irm the reregistration eligibility decision docum ented in this RED.
Table 14. Data Requirements for the Reregistr ation Eligibility Decision on Thidiaz u ron

Guideline Study Name New OPPTS Guideline No. Old Guideline No. Avian Chronic Tests on the Mallard Duck and Bobwhite Quail 850.2300 71-4A Tier 2 Terrestrial Plant Toxicity (seedling em ergence) on Onion and Oat 850.4225 123-1A Residue Analytical Method – Livestock 860.1340 171-4D Storage Stability Data – Plant and Livestock 860.1380 171-4E

32Guideline Study Name New OPPTS Guideline No. Old Guideline No. Meat, Milk, Poultry, and Eggs – (Additional data for the rum i nant feeding study are required). 860.1480 171-4J

2. Labeling for Manufacturing-Use Products
To ensure com p liance with FIFRA and to be eligible for reregistration, m a nufacturing use product (MUP) labeling m u st be revised to com p ly with all current EPA regulations, PR Notices, and applicable policies. Currently, there are only a few label language statem ents needed for reregistration eligibility for thidiazuron. Therefore, the labeling m u st bear the following statem ents contained in Table 15.

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 the pesticide af ter a determ ination of eligibility has been m a de. The Registrant
m

u st review previous data subm issions to ensure that they m eet current EPA acceptance criteria and if not, com m it to conduct new studies. If a registrant believes that previously subm itted data
m eet current testing standards, then the study MRID num bers should be cited according to the instructions in the Requirem e nt Status a nd Registrants Response Form provided for each product. The Agency intends to issue a separate product-specific data call-in (PDCI), outlining specific data requirem e nts.
2. Labeling for End-Use Products In order to be eligible for reregistration, all thidiazuron product labels m u st be am ended to incorporate the risk m itigation m easures outlined in Section IV of this docum ent. (See Table 15).
C. Labeling Changes Summary Table

In order to be eligible for reregistration, am end all product labels to incorporate the required language outlined in Section IV and V of this docum ent. The following table (Table 15) describes how language on the labels should be am ended.

33Table 15:Summary of Labeling Changes for ThidiazuronDescriptionAmended Labeling LanguagePlacement on LabelManufacturing Use ProductsFor allManufacturing UseProducts“Only for formulation into an herbicide for the following uses(s) [fill blank only with those uses that arebeing supported by MP registrant.]”Directions for UseOne of thesestatements may beadded to a label toallow reformulationof the product for aspecific use or alladditional usessupported by aformulator or usergroup“This product may be used to formulate products forspecific use(s) not listed on the MP label if theformulator, user group, or grower has complied withU.S. EPA submission requirements regarding supportofsuchuse(s).”“This product may be used to formulate products for any additional use(s) not listed on the MP label if theformulator, user group, or grower has complied withU.S. EPA submission requirements regarding supportof such use.”Directions for UseEnvironmental HazardsStatements Required by theRED and Agency LabelPolicies"Do not discharge effluent containing this product into lakes,streams, ponds, estuaries, oceans, or other waters unless inaccordance with the requirements of a National Pollution DischargeElimination System (NPDES) permit and the permitting authority hasbeen notified in writing prior to discharge.Do not dischargeeffluent containing this product to sewer systems withoutpreviously notifying the local sewage treatment plant authority.For guidance contact your State Water Board or Regional Office ofthe EPA."Directions for UseEnd Use Products Intended for Occupational UsePPE RequirementsEstablished by the RED forall Formulations“Personal Protective Equipment (PPE)All mixers, loaders and applicators must wear:-Long sleeved shirt,-Long pants, and-Shoes and socks.”PrecautionaryStatements –Immediately followingHazards to Humansand Domestic Animals34DescriptionAmended Labeling LanguagePlacement on LabelSee Engineering Controls for Requirements.”Engineering Controls forAerial ApplicationEnclosed Cockpits“Engineering Controls:Pilots must use an enclosed cockpit that meets the requirements listed in the WPS for agriculturalpesticides [40 CFR 170.240(d)(6)].”PrecautionaryStatements ­Immediately followingPPE and User SafetyRequirementsUser Safety Requirements“Follow manufacturer’s instructionsfor cleaning/maintaining PPE.If no such instructions forwashables exist, use detergent and hot water.Keep and wash PPE separately fromother laundry.”PrecautionaryStatements –Immediately followingthe PPE RequirementsUser SafetyRecommendations“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 puton clean clothing.”“Users should remove PPE immediately after handlingthis product.Wash the outside of gloves beforeremoving.As soon as possible, wash thoroughly and change into clean clothing.”[Note: Glove statements can be removed if the acutetoxicity testing of the end use product does not requiregloves]PrecautionaryStatements –Immediately followingEngineering Controls35DescriptionAmended Labeling LanguagePlacement on LabelEnvironmental Hazards“Do not apply directly to water, or toareas where surface water is present or to intertidal areasbelow the mean high water mark.Do not contaminate water when disposing of equipmentwashwater or rinsate.”“This product may contaminate water through driftof spray in wind.This product has a highpotential for runoff for several months or more after application.Poorly draining soils and soilswith shallow water tables are more prone to produce runoff that contains this product.A level,well-maintained vegetative buffer strip between areas to which this product is applied and surfacewater features such as ponds, streams, and springs will reduce the potential for contamination ofwater fromrunoff.Runoff of this product will bereduced by avoiding applications when rainfall isforecasted to occur within 48 hours.Sound erosion control practices will reduce this product’scontribution to surface water contamination.”“This chemical has properties and characteristicsassociated with chemicals detected in groundwater.Use of this chemical in areas where soilsare permeable, particularly where the water table isshallow, may result in groundwater contamination.”PrecautionaryStatements immediatelyfollowing the UserSafetyRecommendationsRestricted Entry Interval“Do not enter or allow worker entry into treated areas during the restricted entry interval of 24hours.”Directions for Use –Agricultural UseRequirements boxEarly Reentry PersonalProtective Equipment forProducts subject to WPS asrequired by Supplement Threeof PR Notice of 93-7“PPE required for early entry to treated areas thatis permitted under the Worker Protection Standard andthat involves contact with anything that hasbeen treated, such as soil or water, is:For all end-use products:-coveralls,-chemical-resistant gloves made of any waterproof material,- shoes plus socks.”Directions for Use,Agricultural UseRequirements BoxApplication RestrictionsThe following label recommendationsmust be reflected in the directions for use:36General Use Rate Information (under normal conditions) for Cotton:0.125lbs ai/AMaximumapplication rate of0.3 lbs ai/A/yearMaximumof 2 applications, but not to exceed 0.3 lbs ai/A/year.General Use Rate Information (under variable conditions) for Cotton:(See section IV- A for more detailed information)Maximumapplication rate of0.2 lbs ai/AMaximumapplication rate of0.3 lbs ai/A/yearMaximumof 2 applications, but not to exceed 0.3 lbs ai/A/year.Additional language and application rates(in bold)to be added to existing end-use product labelscontaining only the active ingredient Thidiazuron:For cutout and mature cotton under normal weather patterns, use (insert product name) at0.05to 0.10 lb. active ingredient per acre.The0.05 lb. rate is most effective when used in atankmix with other cotton defoliant products.Increased rates of (insert product name) above 0.10 lb. of active ingredient per acre may beneeded to defoliate and control regrowth during periods of rankgrowth/high fertilizerconditions, extreme weather conditions, such as extended periods of rain and/or lowtemperatures (60°–65°F), and onfull-season cotton varieties.37Additional language(in bold)to be added to existing products that contain a mixture ofThidiazuron and Diuron:TANK MIXOF (insert product name) plus other cotton defoliant products.The tankmix of (insert product name) plus other cotton defoliant products is recommended toimprove overall defoliation, and as an aid inaccelerating the opening of mature, unopenedcotton bolls. Best activity will be obtained where the tankmix is applied to mature cottonplants.Do not apply tankmix before sufficient unopened bolls have matured to produce thedesired cotton yield.For cotton produced in non-arid conditions, apply (insert product name) at a rate of 3.2 to 6.4fluid ounces per acre plus other cotton defoliant products at a rate of 21 to 42 fluid ounces peracre.For cotton produced in arid conditions, apply (insert product name) at a rate of 6.4 to 16 fluidounces per acre plus other cotton defoliant products at a rate of 21 to 42 fluid ounces peracre.To Achieve an ApplicationRate of:Use This Amount of ProductAt the Indicated Rate, OneGallon of Product Will Treat:0.07 lbs. ai/Acre2.3 fluid oz/A56 Acres0.17 lbs. ai/Acre5.4 fluid oz/A23.5 AcresApplication Restrictions forDriftThidiazuron products can not be applied by air within 1⁄2 mile of lettuce or 5 miles downwind of thepoint of application when citrus is in flush (burst of new growth, as in springtime) in the RioGrande valley of Texas.Ground applications are restricted to 100 feet away fromlettuce and 1⁄2mile downwind fromthe point of application for citrus.(In general, a decrease in droplet size or increasein wind speed at the time of application will resultin risk to non-target organisms.Alternatively,if droplet size is coarseror wind speeds are lower,exposures due to drift would be reduced).Directions for Use,Agricultural UseRequirements BoxInstructions in theLabelingsection appearing in quotations represent theexact language that should appear on the label.Instructions in theLabelingsection not in quotes represents actions that the registrant should take to amend their labels or product registrations.38

## VI. Appendices

39Appendix A:Use Patterns Subject to Reregistration for Thidiazuron (Case 4092)Use SiteFormulationMax. SingleApp. RateUnitMax # App.Per CropCycle/YrMax App.Rate PerCropCycle/YrMin.RestrictionInterval(Days)ReentryInterval(REI)PreharvestInterval(PHI)RestrictionCommentsCottonWettablePowder(WP)[50% a.i.]SolubleConcentrate(SC)[12% a.i.]EmulsifiableConcentrate(EC)[8.4 - 50% a.i.]0.125*[for end-useproducts undernormalconditions]0.2*[for end-useproducts undervariableconditions]Lbs ai/acre2 per season0.3 lbs ai/acreN/A24 hoursMinimumPHI= 5 days*Refer toLabelChangesSummaryTable in theThidiazuronRED.40Appendix B. Table of Generic Data Requirements and Studies Used to Make the Reregistration Decision
GUIDE TO APPENDIX B Appendix B contains listing of data requirem e nts which support the reregistration for active ingredients within the case 0153 covered by this IRED. It contains generic data requirem e nts that apply to m e thyl parathion in all products, including data requirem e nts for which a "typical form ulation" is the test substance. The data table is organized in the following form ats:
1. Data Requirem e nt (Colum n 1). The data requirem e nts are listed in the order in which they appear in 40 CFR part 158. The reference num bers accom p anying each test refer to the test protocols set in the Pesticide Assessm ent Guidance, which are available from the National technical Inform ation Service, 5285 Port Royal Road, Springfield, VA 22161 (703) 487-4650.
2. Use Pattern (Colum n 2). This colum n indicates the use patterns for which the data requirem e nts 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 m e dical O. Indoor residential
3. Bibliographic Citation (Colum n 3). If the Agency has acceptable data in its files, this colum n list the identify num ber of each study. This norm a lly is the Master Record Identification (MIRD) num ber, but m a y be a "GS" num ber if no MRID
num ber has been assigned. Refer to the Bibliography appendix for a com p lete citation of the study.

41

# APPENDIX B Data Supporting Guideline Requirements for the Reregistration of Thiabendaz ole

REQUIREMENT USE PATTERN CITATION(S)

PRODUCT CHEMISTRY
New Guideline Number Old Guideline Number 830.1550 61-1 Product Identity and Com position All 45915701 830.1600 61-2A Start. Mat. & Mnfg. Process All 45915701
830.1620 61-2B Description of Production Process All 45915701
830.1670 61-2B Form ation of Im purities All 45915701 830.1700 62-1 Prelim inary Analysis All 45915701 830.1750 62-2 Certification of lim its All 45915701 830.1800 62-3 Enforcem ent Analytical Method All 45915701
830.6302 63-2 Color All 45934001 830.6303 63-3 Physical State All 45934001 830.6304 63-4 Odor All 45934001 830.6313 63-13 Stability to Norm al and Elevated Tem p eratures, Metals and Metal Ions All 45934001

830.6314 63-14 Oxidation/Reduction: Chem ical Incom p atibility All 45934001

830.6315 63-15 Flam m a bility All N/A 830.6316 63-16 Explodability All 45934001 830.6317 63-17 Storage Stability All 45934001; Study (1 year) in progress and m u st be subm itted to the Agency upon com p letion. 830.6319 63-19 Miscibility All N/A 830.6320 63-20 Corrosion Characteristics All 45934001; Study (1 year) in progress and m u st be subm itted to the Agency upon com p letion. 830.7000 63-12 pH All 45934001

42���� �� ����������������������������� ���� ��� ����������������������������������� ������������������������������ ���� �� ����������������������������� ���� ��� ����������������������������������� ������������������������������

���� �� ����������������������������� ���� ��� ����������������������������������� ������������������������������
���� ��� ����������������������������������� ������������������������������
���� �� ����������������������������� ���� �� ����������������������������� ���� ��� ����������������������������������� ������������������������������
���� �� ����������������������������� Data Supporting Guideline Requirements for the Reregistration of Thiabendaz ole

REQUIREMENT USE PATTERN CITATION(S)

830.7050 None UV/Visable Absorption All 45934001
830.7100 63-18 Viscosity All N/A
830.7200 63-5 Melting Point All 45934001 830.7220 63-6 Boiling Point All N/A 830.7300 63-7 Relative Density All 45934001 830.7370 63-10 Dissociation Constants in W a ter All 41364901 830.7550 63-11 Octanol/W ater Partition Coefficient All 41364906 830.7840 63-8 W a ter solubility: colum n elution
m e thod; shake flask m e thod All 41364906 and 41786202

830.7950 63-9 Vapor Pressure All 94246001 ECOLOGICAL EFFECTS 850.2100 71-1 Avian Acute Oral Toxicity ���� ���� ��� ��� � ������������������������ ����� ������������������������������ 099189 850.2200 71-2A Avian Dietary Toxicity - Quail ���� ��� ����������������������������������� ������������������������������ 0081629, 46203502
850.2200 71-2B Avian Dietary Toxicity - Duck ���� ����������������������������� �� 00066169 850.2300 71-4 Avian Reproduction –Avian chronic tests on the Mallard Duck and Bobwhite Quail ���� ��� � ����������������������������� ����� � ����������������������������� ����� ����������������������������������� ������������������������������

� ������������������������ ����� Data Gap; Avian Chronic Tests (Mallard Duck and Bobwhite Quail) are required. 850.1075 72-1A Fish Toxicity- Bluegill ���� ���� ��� ��� ������������������������������ 42069201 850.1075 72-1C Fish Toxicity- Rainbow Trout ���� ��� ����������������������������������� ������������������������������ 42069202, 46203511, 46203515 850.1010 72-2A Invertebrate Toxicity ���� ��� � ����������������������������� ����� ����������������������������������� ������������������������������
� ������������������������ ����� 099189, 00066167, 46203509, 46203503, 46203516 850.1075 72-3A Estuarine/Marine Toxicity - Fish ���� ���� ��� ��� ������������������������������ 41846101 850.1025 72-3B Estuarine/Marine Toxicity - Mollusk ���� ����������������������������� �� 42132001 850.1035 850.1045 72-3C Estuarine/Marine Toxicity - Shrim p ���� ��� � ����������������������������� ����� ����������������������������������� ������������������������������ 41846101

850.1300 72-4A Freshwater Fish- Early Life Stage ���� ����������������������������� �� 42270301

43���� ��� ����������������������������������� ������������������������������ ���� �� ����������������������������� ���� ��� ����������������������������������� ������������������������������
���� ��� ����������������������������������� ������������������������������ ���� �� ����������������������������� ���� ��� ����������������������������������� ������������������������������
���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� �����������������������������
���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� ��� ����������������������������������� ������������������������������
���� �� ����������������������������� ���� ��� ����������������������������������� ������������������������������ Data Supporting Guideline Requirements for the Reregistration of Thiabendaz ole

REQUIREMENT USE PATTERN CITATION(S)

850.1350 72-4B Estuarine/Marine Invertebrate Life Cycle ���� ��� ����������������������������������� ������������������������������ � ������������������������ ����� 42132002

850.1500 72-5 Life Cycle Fish ���� ���� ��� �� ������������������������������ N/A 850.4100 122-1A Terrestrial Toxicity; Seedling Em ergence ���� ��� ����������������������������������� ������������������������������ 41821301

850.4150 122-1B Terrestrial Plant Toxicity; Vegetative Vigor ���� ��� ����������������������������������� ������������������������������ � ������������������������ ����� 41819101

850.5400 122-2 Aquatic Plant Growth ���� ���� ��� �� ������������������������������ N/A 850.4225 123-1A Seed Germ ination and Seedling Em ergence (Tier 2) ���� ��� � ����������������������������� ����� ����������������������������������� ������������������������������ 45908501; Data Gap- (onion and oat) 850.4250 123-1B Vegetative Vigor (Tier 2) ���� ����������������������������� �� � ������������������������ ����� 45921501 850.4400 123-2 Aquatic Plant Growth (Tier2) ���� ���� ��� ��� ������������������������������ 46203504 850.3020 141-1 Honey Bee Acute Contact ���� ���� ��� ��� � ������������������������ ����� ������������������������������ 46203501, 46203518 850.3030 141-2 Honey Bee Residue on Foliage ���� ����������������������������� �� N/A TOX I COLOGY 81-1 Acute Oral Toxicity ���� ���� ��� ��� � ������������������������ ����� ������������������������������ 46121501 870.1200 81-2 Acute Derm al Toxicity-Rat ���� ����������������������������� �� � ������������������������ ����� 46121502 870.1300 81-3 Acute Inhalation Toxicity-Rat ���� ���� ��� ��� ������������������������������ 46121503 870.2400 81-4 Prim ary Eye Irritation-Rabbit ���� ���� ��� ��� � ������������������������ ����� ������������������������������ 42099601 870.2500 81-5 Prim ary Skin Irritation- Rabbit ���� ����������������������������� �� � ������������������������ ����� 42099602 870.2600 81-6 Derm al Sensitization- Guinea pig ���� ���� ��� ��� ������������������������������ 46121504 870.6100 81-7 Acute Delayed Neurotoxicity - Hen ���� ���� ��� ��� � ������������������������ ����� ������������������������������ N/A 870.6100 82-5A 90-Day Neurotoxicity- Hen ���� ����������������������������� �� � ������������������������ ����� N/A 870.6200 81-8 Acute Neurotox. Screening Battery-Rat ���� ���� ��� �� ������������������������������ N/A 870.6200 82-7 90-Day Neurotox. Screening BatteryRat ���� ���� ��� ��� ����������������������������������� � ������������������������ ����� ������������������������������ N/A

870.6300 83-6 Developm ental Neurotoxicity Study ���� ����������������������������� �� � ������������������������ ����� N/A 870.3100 82-1A 90-Day Feeding - Rodent ���� ���� ��� ��� ����������������������������������� ������������������������������ 46121505, 46121506, 46121509

44���� ��� ����������������������������������� ������������������������������

���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� ��� ����������������������������������� ������������������������������
���� �� ����������������������������� ���� �� ����������������������������� ���� ��� ����������������������������������� ������������������������������
���� �� ����������������������������� ���� ��� ����������������������������������� ������������������������������ ���� �� ����������������������������� ���� �� ����������������������������� ���� ��� ����������������������������������� ������������������������������ ���� ��� ����������������������������������� ������������������������������
���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� �����������������������������
���� �� ����������������������������� Data Supporting Guideline Requirements for the Reregistration of Thiabendaz ole

REQUIREMENT USE PATTERN CITATION(S)

870.3150 82-1B 90-Day Feeding - Non-rodent ���� ��� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� ����������������������������������� ������������������������������

� ������������������������ ����� No subchronic oral study is required at this tim e, since the toxicological data requirem e nts for 90-day feeding study in non-rodents are satisfied by the 1-yr. feeding study in dogs. 870.3200 82-2 28-Day Derm al Toxicity- Rat ���� ���� ��� ��� ������������������������������ 46261501 870.3250 82-3 90-Day Derm al ���� ����������������������������� �� N/A 870.3465 82-4 90-Day Inhalation-Rat ���� ����������������������������� �� � ������������������������ ����� N/A 870.4100 83-1B Chronic Feeding Toxicity - NonRodent (Dog) ���� ���� ��� ��� ����������������������������������� ������������������������������ 00159344

870.4200 83-2B Oncogenicity - Mouse ���� �� ������������������������ ����� 46346001 870.3700 83-3A Developm ental Toxicity - Rat ���� ����������������������������� �� � ������������������������ ����� 00077126, 00077127 870.3700 83-3B Developm ental Toxicity - Rabbit ���� ���� ��� ��� ����������������������������������� ������������������������������ 46121507, 46252001, 46241001 870.3800 83-4 2-Generation Reproduction - Rat ���� ���� ��� ��� � ������������������������ ����� ������������������������������ 46209601 870.4300 83-5 2-year Com b ined Chronic/Oncogenicty- Rat ���� ��� ����������������������������������� ������������������������������ � ������������������������ ����� 00159346, 46345201

870.5100 84-2 Mutagenicity-Gene Mutation- bacterial ���� ���� ��� ��� ������������������������������ 46121508 870.5265 None Reverse Gene Mutation Assay ���� ���� ��� ��� � ������������������������ ����� ������������������������������ 46121508 870.5300 84-2 Mutagenicity-Gene Mutationma mma l i a n ���� ��� ����������������������������������� ������������������������������ � ������������������������ ����� 41761102

870.5375 84-2B Mutagenicity- Structural Chrom o som a l Abberations ���� ���� ��� ��� ����������������������������������� ������������������������������ 46121510

870.5385 84-2 Micronuleus Assay ���� ���� ��� ��� � ������������������������ ����� ������������������������������ 070129 870.5550 84-2 Unscheduled DNA Synthesis Assay ���� ����������������������������� �� � ������������������������ ����� 41761103 None 84-4 Other Genotoxic Effects ���� ���� ��� �� ������������������������������ N/A 870.7485 85-1 General Metabolism

- Rat ���� ���� ��� ��� � ������������������������ ����� ������������������������������ 42529001 870.7600 85-2 Derm al Penetration ���� ����������������������������� ��

46261502 OCCUPATIONAL/RESIDENTIAL EX POSURE 875.1500 235 Biological Monitoring ���� ���� ��� ��� � ������������������������ ����� ������������������������������ N/A; No residential uses

45���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� ��� ����������������������������������� ������������������������������
���� ��� ����������������������������������� ������������������������������

���� �� ����������������������������� ���� �� ����������������������������� ���� ��� ����������������������������������� ������������������������������ ���� ��� ����������������������������������� ������������������������������
���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� �� ����������������������������� ���� ��� ����������������������������������� ������������������������������ Data Supporting Guideline Requirements for the Reregistration of Thiabendaz ole

REQUIREMENT USE PATTERN CITATION(S)

875.2100 132-1A Foliar Residue Dissipation ���� ����������������������������� �� � ������������������������ ����� N/A; No residential uses

875.2200 132-1B Soil Residue Dissipation ���� ���� ��� �� ������������������������������ N/A; No residential uses

875.2400 133-3 Derm al Passive Dosim e try Exposure ���� ����������������������������� �� N/A; No residential uses

875.2500 133-4 Inhalation Passive Dosim e try Exposure ���� ����������������������������� �� � ������������������������ ����� N/A; No residential uses

None 231 Estim ation of Derm al Exposure at Outdoor Sites ���� ���� ��� ��� ����������������������������������� ������������������������������ N/A; No residential uses

None 232 Estim ation of Inhalation Exposure at Outdoor Sites ���� ��� ����������������������������������� ������������������������������ N/A; No residential uses

ENVIRONMENTAL FATE � ������������������������ ����� None 160-5 Chem ical Identity ���� ���� ��� �� ������������������������������ N/A 835.2120 161-1 Hydrolysis ���� �� ������������������������ ����� 42069203 835.2240 161-2 Photodegradation - W a ter ���� ��� ����������������������������������� ������������������������������ � ������������������������ ����� 41188201, 41364910, 43075202, 44436901 835.2410 161-3 Photodegradation - Soil ���� ���� ��� ��� ����������������������������������� ������������������������������ 00156241, 41364902, 44436901 835.2370 161-4 Photodegradation - Air ���� ���� ��� ��� � ������������������������ ����� ������������������������������ N/A 835.4100 162-1 Aerobic Soil Metabolism ���� ����������������������������� �� � ������������������������ ����� 41950101, 46119601 835.4200 162-2 Anaerobic Soil Metabolism ���� ���� ��� ��� ������������������������������ 41945201 835.4400 162-3 Anaerobic Aquatic Metabolism ���� ���� ��� ��� � ������������������������ ����� ������������������������������ 42666101 835.4300 162-4 Aerobic Aquatic Metabolism ���� ����������������������������� �� � ������������������������ ����� N/A 835.1240 163-1 Leaching/Adsorption/Desorption ���� ���� ��� ��� ������������������������������ 41364909 835.1410 163-2 Laboratory Volatilization ���� ���� ��� ��� � ������������������������ ����� ������������������������������ N/A 835.8100 163-3 Volatility- Field ���� ����������������������������� �� � ������������������������ ����� N/A 835.6100 164-1 Terrestrial Field Dissipation ���� ���� ��� �� ������������������������������ 41761105, 44454001 835.6200 164-2 Aquatic Field Dissipation ���� ���� ��� ��� � ������������������������ ����� ������������������������������ N/A 835.6300 164-3 Forestry Dissipation ���� ����������������������������� �� � ������������������������ ����� N/A 860.1950 165-4 Bioaccum u lation in Fish ���� ���� ��� �� ������������������������������ N/A
None 165-5 Bioaccum u lation- Aquatic Nontarget ���� ���� ��� ��� � ������������������������ ����� ������������������������������ N/A 835-7100 166-1 Ground W a ter- Sm all Scale Prospective ���� ��� ����������������������������������� ������������������������������ N/A

46���� �� ����������������������������� ���� ��� ����������������������������������� ������������������������������
���� ��� ����������������������������������� ������������������������������

���� �� ����������������������������� ���� ��� ����������������������������������� ������������������������������

���� ��� ����������������������������������� ������������������������������
���� ��� ����������������������������������� � �����

����

��� ����������������������������������� ������������������������������

���� ��� ����������������������������������� ������������������������������ Data Supporting Guideline Requirements for the Reregistration of Thiabendaz ole

REQUIREMENT USE PATTERN CITATION(S)

840.1100 201-1 Spray Droplet Size Spectrum ���� ����������������������������� �� � ������������������������ ����� SDTF data 840.1000 201-4 Background for Pesticide Aerial Drift (Evaluation) ���� ���� ��� ��� ����������������������������������� ������������������������������ N/A

840.1200 202-1 Spray Drift Field Deposition (Evaluation) ���� ��� � ����������������������������� ����� ����������������������������������� ������������������������������ SDTF data

RESIDUE CHEMISTRY � ������������������������ ����� 860.1100 171-2 Chem ical Identity ���� ���� ��� �� ������������������������������ N/A 860.1300 171-4A Nature of Residue - Plants ���� ���� ��� ��� � ����������������������������� ����� ����������������������������������� ������������������������������ � ������������������������ ����� 94246026, 94246037, 94246027, 94246038, 94246028, 94246039 860.1300 171-4B Nature of Residue - Livestock ���� ��� ����������������������������������� ������������������������������ ������������������������ 42529002, 42529003, 42778001, 42778002 860.1340 171-4C Residue Analytical Method - Plants ���� ��� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� ����������������������������������� ������������������������������

� ������������������������ ����� 94246030, 94246029, 94246040, 41950102 [Pending m e thods for MRIDs 44558701 and 44143601]. 860.1340 171-4D Residue Analytical Method - Livestock ���� ���� ��� ��� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� ����������������������������������� ������������������������������ Data Gap; Anim al analytical m e thods have been unsuccessful in sim u ltaneously quantifying thidiazuron, 4-hydroxy thidiazuron, and phenylurea; unacceptable MRID 43869001. 860.1380 171-4E Storage Stability Data- Plant and Livestock ���� ��� � ����������������������������� ����� ����������������������������������� ������������������������������ Data Gap; UnacceptableMRID 46298404 and 42847601.

47���� ��� ����������������������������������� ������������������������������

���� ��� ����������������������������������� ������������������������������

���� ��� ����������������������������������� ������������������������������ ���� ��� ����������������������������������� ������������������������������
���� ��� ����������������������������������� ������������������������������ Data Supporting Guideline Requirements for the Reregistration of Thiabendaz ole

REQUIREMENT USE PATTERN CITATION(S)

860.1480 171-4J Magnitude of Residues ­ Meat/Milk/Poultry /Egg ���� ��� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� � ����������������������������� ����� ����������������������������������� ������������������������������ Data Gap; 43781901 (upgradable). Additional data for the rum i nant feeding study are required: storage stability data, raw data to support findings in the study, and an analytical enforcem ent m e thod that sim u ltaneously quantifies residues of thidiazuron and its two livestock
m e tabolites. Also, the poultry feeding study requirem e nt has been waived; 43940701. 860.1500 171-4K Crop Field Trials ���� ��� � ����������������������������� ����� ����������������������������������� ������������������������������ 94246031, 94246041, 94246033, 94246042, 46341001 860.1520 171-4L Magnitude of Residue in Processed Food/Feed ���� ��� ����������������������������������� ������������������������������ � ������������������������ ����� 43940701, 44143601

860.1850 165-1 Confined Accum u lation in Rotational Crops Study ���� ���� ��� ��� ����������������������������������� ������������������������������ 44415501

860.1900 165-2 Field Accum u lation in Rotational Crops Study ���� ��� ����������������������������������� ������������������������������ 46298401

48Appendix C. Technical Support Documents
Additional docum entation in support of this RED is m a intained in the OPP docket, located in Room 119, Crystal Mall #2, 1801 South Bell Street, Arlington, VA. It is open Monday through Friday, excluding Federal Holidays, from 8:30 am to 4 pm

. The docket contains the risk assessm ents and related docum ents as of October 31, 2005. The availability announcem ent will be published in the Federal Register. All docum ents, in hard copy form , m a y be viewed in the OPP docket room or downloaded or viewed via the internet at the f o llowing site: www.epa.gov/pesticides/reregistration

. The f o llowing list details all docum ents related to the Thidiazuron RED.
Health Effects Docum e nts:
1. DP Barcode D244574. Alex Clem . Septem ber 24, 2004. Drinking W a ter Assessm ent.
2. Felicia A. Fort. Septem ber 29, 1995. HED Metabolism Com m ittee Decision following the 9/18/95 m eeting.
3. MRID 43781901. DP Barcode D220968. Stephen Funk. February 15, 1996. Thidiazuron: Response to the Phase 4 Review Magnitude of the Residue in Rum i nants.
4. DP Barcode D319302. Toiya Goodlow. August 31, 2005. Thidiazuron: Revised HED Chapter of the Reregistration Eligibility Decision Docum e nt (RED), Phase 3- Public Com m e nts.
5. Felecia A. Fort. Septem ber 29, 1995. HED Metabolism Com m ittee Decision following the 9/18/95 m eeting.
6. DP Barcode D295368. Shyam B. Mathur. March 1, 2004. Product Chem istry Review of Thidiazuron Technical.
7. Felecia A. Fort. Septem ber 8, 1995. Thidiazuron Metabolism

. 8. MRID No. 44415501. DP Barcode D241202. Toiya Jim e rson. October 26, 2004. Thidiazuron: Registrant’s Response to Residue Chem istry Data Requirem e nts.
9. MRID No. 46298401. DP Barcode D294543. Toiya Jim e rson. Novem b er 8, 2004. Magnitude of Residue in Rotational Crops Following Cotton Treated with DROPP ® SC.
10. MRID No. 42529001. DP Barcode D294560. Byong-Han Chin. Rat Metabolism

.
4911. MRID No. 44558701. DP Barcode D246804. Sherrie L. Mason. January 21, 1999. Independent Laboratory Validation of Analytical Method AW /02/96 for the Analysis of Thidiazuron and Photo-thidiazuron in/on Cottonseed Com m odities.
12. MRID 43781901. DP Barcode D220968. Stephen Funk. February 15, 1996. Thidiazuron: Response to the Phase 4 Review Magnitude of the Residue in Rum i nants.
13. DP Barcode D244574. Alex Clem . Septem ber 24, 2004. Drinking W a ter Assessm ent
14. DP Barcode D316043. Toiya Jim e rson. May 2, 2005. Thidiazuron: Chronic Dietary Exposure Assessm ent for the Reregistration Eligibility Decision- Revised.
15. DP Barcode D311489. Jerry Blondell. Decem ber 21, 2004. Review of Thidiazuron Incident Reports. Ecological Fate and Effects Docum e nts:
1. DP Barcode D244574. Alex Clem . August 24, 2004. Thidiazuron (PC120301): Drinking W a ter Assessm ent

50Appendix D. Citations Considered to be Part of the Data Base Supporting the Reregistration Eligibility Decision (Bibliography) for Thidiaz u ron


## Bibliography
Citation Reference MRID
66167 Vilkas, A.G.; Browne, A.M. (1979) The Acute Toxicity of Thidiazuron Technical to the W a ter Flea Daphnia m a gna: UCES Project No. 11506-74-04. (Unpublished study received Dec. 18, 1980 under 2139-EX-23; prepared by Union Carbide Corp., subm itted by Nor-Am Agricultural Products, Inc., Naperville, Ill.; CDL:099819-C) 66169 Fletcher, D.W

. (1979) Report to..:8-da y Dietary LC50 Study with Thidiazuron, Technical, in Mallard Ducklings:BLAL No. 79 DC 1. (Unpublished study received Dec 18, 1980 under 2139-EX-23; prepared by Bio-Life Associates, Ltd., subm itted by Nor-Am Agricultural Products, Inc., Naperville, Ill.; CDL:099819-F) 77126 Reprotox Gm bH (1981) Thidiazuron (SN 49 537): Teratology Study in the Rat: Reprotox Order No. 413/A. Rev. final re pt. (Unpub- lished study received May 29, 1981 under 2139-122; subm itted by Nor-Am Agricultural Products, Inc., Naperville, Ill.; CDL: 070129-B) 77127 Reprotox Gm bH (1981) Thidiazuron (SN 49 537): Teratology Study in the Rat: Reprotox Order No. 536/A. Rev. final re pt. (Unpub- lished study received May 29, 1981 under 2139-122; subm itted by Nor-Am Agricultural Products, Inc., Naperville, Ill.; CDL: 070129-C) 81629 Fletcher, D.W

. (1981) Report to Nor-Am Agricultural Products, Inc.: 8-day Dietary LC50 Study with Thiazuron, Technical in Bob- white Quail: P.O. #R 818; BLAL No.81 QC 7. (Unpublished study received Sep 3, 1981 under 2939-122; prepared by BioLife Asso- ciates, Ltd., subm itted by Farm er Seed & Nursery, Faribault, Minn.; CDL:245834-A) 099189 Fletcher, Dale 1979. The Acute Oral Toxi city of Thiadiazuron Technical to the Bobwhite Quail. Received January 5, 1981. An unpublished report prepared by BioLife Associates, LTD for NOR-AM Agricultural Products, Inc. 156241 Riem ann, J. (1981) Photodegradation of Thidiazuron (SN 49537) on Soil Surfaces: Report No. APC 07/81. Unpublished study prepared by Schering AG. 37 p. 159344 Khater, A. (1985) SN 49 537: System ic Tolerance Study in Dogs following Daily Adm i nistration via the Feed over a Period of One Year: Report No. PF 55/84: Study No. TX 83.003. Unpublished study prepared by Schering AG and Tierarztlichen Hochschule Hannover. 463 p.

51159346 Sachsse, K. (1986) 104-W eek Chronic Toxicity and Oncogenicity Study with Thidiazuron Technical in the Rat: RCC Project No. 011924. Unpublished study prepared by Research & Consulting Co., AG and Experim e ntal Pathology Consulting AG. 1498 p. 41188201 Brehm , M. (1989) W 63-Thidiazuron: Th e Photodegradation of Thidiazu- ron in Aqueous Solution: Project ID APC 34/09. Unpublished stu- dy prepared by Schering Ag. 101 p. 41364901 Ottnad, M. (1976) C5-Thidiazuron: Determ ination of the Dissociation Constant of SN 49 537h: Lab Project Num b er: PA 49 537.11/5. Unpublished study prepared by Schering AG. 6 p. 41364906 Brehm , M.; Miklautz, H. (1987) C40 Thidiazuron: W a ter Solubility and NOctanol/W ater Partition Coefficient of Th idiazuron (Schering Code No. ZK 49 537): Lab Project No. APC 50/87; Study No. 87/169; 603.30. Unpublished study prepared by Schering AG. 27 p. 41364909 Bruehl, R. (1988) W 61 Thidiazuron: Ab sorption to and Desorption from Soil: Lab Project ID: UPSR 17/88 - PA 49537.7/6; PF-S 87 057; 05.14. Unpublished study prepared by Schering AG Pflanzen- schut z Um welt, Produktsicherheit Registrierung. 46 p. 41364910 Brehm , M. (1989) W 63 Supplem ent Thidiazuron: The Photodegradation of Thidiazuron in Aqueous Solution (Schering Code No. ZK 49537): Lab Project ID: APC 55/89; 87/217; 31.08. Unpublished study prepared by Schering AG. 25 p. 41761102 Heidem ann, A. (1990) T59 Thidiazuron: Gene Mutation Assay in Chinese Ham s ter V79 Cells in Vitro with Thidiazuron Technical (SN 49537): Lab Project Num b er: TB 89 083. Unpublished study prepared by Cytotest Cell Research Gm bh & Co. KG. 30 p. 41761103 Fautz, R. (1990) T58 Thidiazuron: Unscheduled DNA Synthesis in Prim ary Hepatocytes of Male Rats in Vitro with Thidiazuron (SN 49537): Lab Project Num b er: TB 89 084. Unpublished study prepared by Cytotest Cell Research Gm bh & Co. KG. 36 p. 41761104 Hughes, J.S. 1990. The Toxicity of Thiadiazuron Technical to Selenastrum capricornatum. Laboratory Project N. B643-01-3. Conducted by Malcom Pirnie, Inc., Pikeville, NC. 41761105 Rucker, W

. (1990) W 67 Thidiazuron: Di ssipation of Thidiazuron in Soil Following Application of Dropp 50W P to Bare Ground: Lab Project Num b er: 65/90. Unpublished study prepared by Schering AG. 76 p. 41786202 Muller, T. (1991) Thidiazuron Product Chem istry/Solubility in Organic Solvents: Lab Project Num b er: C53, C54, C58. Unpublished prepared by Schering Ag. 70 p. 41819101 Downey, S. (1990) Investigation into th e Phytotoxic Effects of Thi- diazuron on

52Vegetative Vigor (Tier 1): Lab Project Num b er: 502 AW . Unpublished study prepared by Nor-Am Chem ical Co. 132 p. 41821301 Downey, S. (1991) Investigation into th e Phytotoxic Effects of Thi- diazuron on Seedling Em ergence (Tier 1): Lab Project Num b er: 501 AW . Unpublished study prepared by Nor-Am Chem ical Co. 63 p. 41846101 Schupner, J.; Stachura, B. (1991) The Static Acute Toxicity of Thidiazuron to the Sheepshead m i nnow, Cyprinodon variegatus: Lab Project Num b er: 504AW

. Unpublished study prepared by NOR-AM Chem ical Co. 42 p. 41945201 Feyerabend, M. (1991) W 74 Thidiazuron: Anaerobic Degradation of ? U L-? carbon 14||-Phenyl-Thidiazuron in a Sandy Loam Soil at 21 (degree) C: Lab Project Num b er: UPSR 20/91. Unpublished study prepared by Schering Ag. 47 p. 41950101 Feyerabend, M. (1991) W 75 Thidiazuron: Aerobic Degradation of ? U L- carbon 14| Phenyl-Thidiazuron in a Sandy Loam Soil at 21 C: Lab Project Num b er: UPSR 21/91. Unpublished study prepared by Sche- ring AG. 49 p. 41950102 Bowm an, M. (1991) Testing of Thidiazu ron through US FDA Multiresidue Methods: Lab Project Num b er: MCB-NOR-Am / MR-2. Unpublished study prepared by M.C. Bowm an & Associates. 30 p. 42069201 Schupner, J.; Stachura, B. (1991) The Acute Toxicity of Thidiazuron Technical to the Bluegill Sunf ish, Lepom is m acrochirus in a Static System : Lab Project Num b er: 511AW

. Unpublished study prepared by NOR-AM Chem ical Co. 42 p. 42069202 Schupner, J.; Stachura, B. (1991) The Acute Toxicity of Thidiazuron Technical to the Rainbow Trout, Oncorhynchus m ykiss in a Static System : Lab Project Num b er: 512AW

. Unpublished study prepared by NOR-AM Chem ical Co. 42 p. 42069203 Tscham pel, M. (1991) W 78 Thidiazuron: The Determ ination of the Rate of Hydrolysis of Thidiazuron (Schering Code No. ZK 49537): Lab Project Num b er: APC/71/91. Unpublished study prepared by Schering Ag. 28 p. 42099601 Liggett, M.; McRae, L. (1991) Thidiazuron (T-61): Rabbit Eye Irri- tancy Study: Lab Project Num b er: 91703D/SMS 340/SE: TOX 91116. Unpublished study prepared by Huntingdon Research Center, Ltd. 16 p. 42099602 Liggett, M.; McRae, L. (1991) Thidiazuron (T-62): Rabbit Skin Irri- tancy Study: Lab Project Num b er: 91702D/SMS 339/SE: TOX 91115. Unpublished study prepared by Huntingdon Research Centre, Ltd. 15 p. 42132001 W a rd, S. (1991) Thidiazuron Technical: Ac ute Effect on New Shell Growth of, the Eastern Oyster, Crassostrea virginica: Lab Project Num b er: J9101006B. Unpublished study prepared by Toxi- kon Environm ental Sciences. 54 p. 42132002 Blakem ore, G. (1991) Chronic Toxicity of Thidiazuron to Daphnia m a gna Under Flow-through Test Conditions: Final Repor t: Lab Pro- ject Num b er: 39114: 507-AW

.

53Unpublished study prepared by ABC Labs, Inc. 106 p. 42270301 Cohle, P.; Muckerm a n, M. (1992) Early Life-Stage Toxicity of Thidiazuron to Fathead Minnows (Pim ephales prom elas) in a Flow-through System : Lab Project Num b er: 39113: 506/AW . Unpublished study prepared by ABC Laboratories, Inc. 86 p. 42529001 Hawkins, D.; Mayo, B.; McEwen, A.; et al. (1992) M13 Thidiazuron: The Metabolism of ? C arbon 14|-Thidiazuron in Rats: Lab Project Num b er: HRC/SMS/254/920450. Unpublished study prepar ed by Hundington Research Centre Ltd. 77 p. 42529002 Hawkins, D.; Mayo, B.; Pollard, A.; et al. (1992) M13 Thidiazuron: The Metabolism of carbon 14- Thidiazuron in the Cow Part I: Lab Project Num b er: HRC/SMS/255/920556. Unpublished study prepar ed by Hundington Research Centre Ltd. 103 p. 42529003 Hawkins, D.; Mayo, B.; Pollard, A.; et al. (1992) M13 Thidiazuron: The Metabolism of carbon 14- Thidiazuron in the Laying Hens Part I: Lab Project Num b er: HRC/SMS/253/921246. Unpublished study prepar ed by Hundington Research Centre Ltd. 89 p. 42666101 Leake, C.; Allan, J. (1993) The Degradation of (carbon 14)-Thidiazuron under Laboratory Anaerobic Aquatic Conditions: Lab Project Num b er: 508AW

. Unpublished study prepared by Nor-Am Chem ical Co. 64 p. 42778001 Hawkins, D.; Mayo, B.; Pollard, A.; et al. (1993) M-11 Thidiazuron: The Metabolism of (carbon 14)- Thidiazuron in the Laying Hens, Part II—Investigations into Tissue Metabolites: Addendum : Lab Project Num b er: HRC/SMS/253/921246: HRC/SMS 253A/930518: TOX 90461. Unpublished study prepared by Huntingdon Research Centre Ltd. 28 p. 42778002 Hawkins, D.; Mayo, B.; Pollard, A.; et al. (1993) M-12 Thidiazuron: The Metabolism of (carbon 14)- Thidiazuron in the Cow, Part II—Investigations into Tissue Metabolites: Addendum : Lab Project Num b er: HRC/SMS/255/920556: HRC/SMS 255A/930527: TOX 90462. Unpublished study prepared by Huntingdon Research Centre Ltd. 36 p. 42847601 Brady, S. (1993) Stability of Thidiazuron Residues in Cottonseed Analytical Sam p les Freezer-Stored for Four Years, USA, 1989: Lab Project Num b er: E332.02.89. Unpublished study prepared by Nor-Am Chem ical Co. 38 p. 43075202 Brehm , M. (1993) Thidiazuron: The Phot odegredation of Thidiazuron in Aqueous Solution: W 63, Addendum #1: Lab Project Num b er: APC 34/89. Unpublished study prepared by Schering AG. 19 p. 43781901 Castro, L. (1995) Thidiazuron-Derived Resi dues in the Meat and Milk of Dairy Cows Resulting from Oral Ingestion of Thidi azuron (Second Edition): Lab Project Num b er:

54AW -93R-01/02: 139-005-10. Unpublished study prepared by AgrEvo USA Co. 141 p. 43869001 Arguello, A. (1995) Independent Labor atory Validation of the Method of Determ ination of Thidiazuron and Its Metabolites, 4-Hydroxy Thidiazuron and Phenylurea, in Beef Tissues and Milk: Revised Report: Lab Project Num b er: 1435: 1435-1. Unpublished study prepared by Analytical Developm ent Corp. 140 p. 43940701 W illiam s , L. (1996) At-Harvest Thidiazuron Residues In or On Processed Cottonseeds Following Two treatm e nts with DROPP 50W P At Exaggerated Rates, 7 Days PHI, USA, 1994: Lab Project Num b er: AW -94R-08: A55693. Unpublished study prepared by AgrEvo USA Co. 56 p. 44143601 W illiam s , L. (1996) Supplem ent 1 to: At-Harvest Thidiazuron Derived Residues In or On Processed Cottonseeds Following Two treatm e nts with DROPP 50W P At Exaggerated Rates, 7 Days PHI, USA, 1994: Lab Project Num b er: A61009: AW

94R-08: A55693. Unpublished study prepared by AgrEvo USA Co. 59 p. 44415501 Meyer, B.; Tull, P. (1997) Uptake of (5-(carbon 14)-Thiadazol)-Thidiazuron Residues in Soil by Rotational Crops under Confined Conditions: Lab Project Num b er: 524AW : A61011: THIDIAZURON/W 89. Unpublished study prepared by AgrEvo USA Co. 115 p. 44436901 Kelly, I. (1997) Thidiazuron Reregistra tion in the USA: Environm ental Fate Overview, 1997: Lab Project Num b er: 526AW : AW 97E526. Unpublished study prepared by AgrEvo USA Co. 34 p. 44454001 Cam pbell, J.; Singer, S. (1997) Dissipation of Thidiazuron in Soil Following Application of Dropp 50 W P to Bare Soil USA, 1991 (Am e nded Report): Lab Project Num b er: AW -91R-03: A61018: THIDIAZURON/W 88-AMEND. Unpublished study prepared by AgrEvo USA Co. 553 p. 44558701 Koch, D.; Schrier, L. (1998) Independent Laboratory Confirm a tion of Determ ination of Thidiazuron and Photo-Thidiazuron in Cottonseed and Gin Trash by HPLC According to PR Notice 96-1 Guidelines: Lab Project Num b er: 43653: ACFS-43653: AW -96R-03. Unpublished study prepared by ABC Laboratories, Inc. 77 p. 45915701 Sm ith, P. (2002) Analysis of Product Ingred ients in Five Batches of Technical Grade Thidiazuron: Lab Project Num b er: 1136W . Unpublished study prepared by PTRL W e st, Inc. 87 p. {OPPTS 830.1550, 830.1600, 830.1620, 830.1670, 830.1700, 830.1750, 830.1800, 830.1900} 45921501 Teixeira, D. (2003) Thidiazuron SC42 --Determ i nation of Effects on Vegetative Vigor of Ten Plant Species: Lab Project Num b er: B004268: 13798.6114: 02AW 38345A. Unpublished study prepared by Springborn Sm ithers Laboratories. 157 p. {OPPTS 850.4150 and 850.4250} 45934001 Sm ith, P.; Cunningham , M. (2003) Physical/Chem i cal Characteristics of Thidiazuron

55Tech: Lab Project Num b er: 1152W : KRR-071-02. Unpublished study prepared by PTRL W e st, Inc. and Kinetica, Inc. 55 p. {OPPTS 830.6302, 830.6303, 830.6304, 830. 6313, 830.6314, 830.6316, 830.7000, 830.7050, 830.7200, 830.7300} 46119601 Allan, J. (2003) The Kinetics of Degradation of ((Carbon 14)-Thiadiazol)- Thidiazuron in Three Soils at 20 Degrees C Under Laboratory Aerobic Conditions. Project Num b er: B004299, 601AW , 601AW / F/218/221. Unpublished study prepared by Bayer CropScience LP. 78 p. 46121501 Colem a n, D. (2001) Rat Acute Oral T oxicity: Thidiazuron. Project Num b er: AES/026/004785/AC, TOX/201338. Unpublished study prepared by Huntingdon Life Sciences, Ltd. 22 p. 46121502 Colem a n, D. (2001) Rat Acute Derm al Toxicity: Thidiazuron. Project Num b er: AES/027/004628/AC, TOX/20139. Unpublished st udy prepared by Huntingdon Life Sciences, Ltd. 18 p. 46121503 W e sson, C. (2001) Acute Inhalation Toxicity (Nose Only) Study in the Rat: Thidiazuron (AE B049537). Project Num b er: 374/096, TOX/20142. Unpublished study prepared by Safepharm Laboratories, Ltd. 46 p. 46121504 Colem a n, D. (2001) Guinea-Pig Skin Sensitization Study (Magnusson & Kligm a n Method): Thidiazuron. Project Num b er: AES/028/012112/SS, TOX/20140. Unpublished study prepared by Huntingdon Life Sciences, Ltd. 31 p. 46121505 Foulon, O. (2001) Thidiazuron: 90-Day Toxicity Study in the Mouse by Dietary Adm i nstration: (Final Report). Proj ect Num b er: SA/00593, K01/013, RTI/806/AN. Unpublished study prepared by Aventis Cropscience. 304 p. 46121506 Foulon, O. (2001) Thidiazuron: 90-Day Toxicity Study in the Rat by Dietary Adm i nstration: (Final Report). Proj ect Num b er: SA/00491, K01/003. Unpublished study prepared by Aventis Cropscience. 508 p. 46121507 W a son, S. (2003) Thidiazuron: Developm ental Toxicity Study in the Rabbit by Gavage. Project Num b er: SA/02046. Unpublished study prepared by Bayer Cropscience. 237 p. 46121508 Kitching, J. (2001) Bacterial Mutation Assay: Thidiazuron. Project Num b er: AES/036, AES/036/004461, TOX/20144. Unpublished study prepared by Huntingdon Life Sciences, Ltd. 29 p. 46121509 Steiblen, G. (2003) Thidiazuron: 28-Da y Toxicity Study in the Rat by Dietary Adm i nstration (Investigation of Rena l Function). Project Num b er: SA/01245. Unpublished study prepared by Bayer Cropscience. 179 p. 46121510 Gudi, R.; Brown, C. (2001) In Vitro Mam m a lian Chrom o som e Aberration Test: Final Report. Project Num b er: AA39KC/341/B TL, SPGT341. Unpublished study prepared by Bioreliance. 37 p.

5646203501 King, A. (2003) Assessm ent of Side Effects of AE B049537 00 1D99 0003 (Thidiazuron, techn.) to the Honey Bee, Apis m e llifera L. in the Laboratory: (Final Report). Project Num b er: 20021341/01/BLEU, C029693. Unpublished study prepared by GAB Biotechnologie Gm bh. 26 p. 46203502 Bowers, L. (2003) Technical Thidiazuron: A Subacute Dietary LC50 with Northern Bobwhite. Project Num b er: TN721701, 200522, B004266. Unpublished study prepared by Bayer CropScience. 39 p. 46203503 Blankinship, A.; Palm er, S.; Kendall, T.; et . al. (2003) Thidiazuron: A 48-Hour Static Acute Toxicity Test with the Cladoceran (Daphnia m a gna): Final Report. Project Num b er: 149A/151, C032042. Unpublished study prepared by W ildlife International, Ltd. 40 p. 46203504 Desjardins, D., Kendall, T., and Krueger, H. 2003. Thidiazuron: A 72-Hour Toxicity Test with the Freshwater Alga ( Anabaena flos-aquae ). Unpublished study perform e d by W ildlife International, Ltd., Easton, Maryland. Laboratory Study No. 149A-152. Study sponsored by Bayer CropScience, Frankfurt am Main, Germ any. Experim e ntal start date April 7, 2003 and experim e ntal term ination date April 10, 2003. The final report issued April 25, 2003. 46203505 Desjardins, D., Kendall, T., and Krueger, H. 2003. Thidiazuron: A 96-Hour Toxicity Test with the Marine Diatom ( Skeletonema costatum ). Unpublished study perform e d by W ildlife International, Ltd., Easton, Maryland. Laboratory Study No. 149A-153. Study sponsored by Bayer CropScience, Frankfurt am Main, Germ any. Experim e ntal start date April 21, 2003 and experim e ntal term ination date April 25, 2003. The final report issued June 5, 2003. 46203506 Desjardins, D., Kendall, T., and Krueger, H. 2003. Thidiazuron: A 7-Day StaticRenewal Toxicity Test with Duckweed ( Lemna gibba ). Unpublished study perform e d by W ildlife International, Ltd., Easton, Maryland. Laboratory Study No. 149A-154. Study sponsored by Bayer CropScience, Frankfurt am Main, Germ any. Experim e ntal start date April 1, 2003 and experim e ntal term ination date April 8, 2003. The final report issued May 6, 2003. 46203509 Blankinship, A.; Palm er, S.; Kendall, T.; et al. (2003) AE F132347: A 48-Hour Acute Toxicity Test with the Cladoceran (Daphnia m a gna): Final Report. Project Num b er: C032043, 149A/155. Unpublished study prepared by W ildlife International, Ltd. 41 p. 46203510 Desjardins, D., Kendall, T., and Kr ueger, H. 2003. AE F132347: A 72-Hour Toxicity Test with the Freshwater Alga ( Scenedesmus subspicatus ). Unpublished study perform e d by W ildlife International, Ltd., Easton, Maryland. Laboratory Study No. 149A-157. Study sponsored by Bayer CropScience, Frankfurt am Main, Germ any. Experim e ntal start date May 12, 2003 and experim e ntal term ination date May 15, 2003. The final report issued June 19, 2003.

5746203511 Palm er, S.J., et al. 2003. AE C421200: A 96-Hour Static Acute Toxicity Test with the Rainbow Trout ( Oncorhynchus mykiss ). Unpublished study perform e d by W ildlife International, Ltd., Easton, MD. Laboratory Project No. 149A-159. Study sponsored by Bayer CropScience, Frankfurt am Main, Germ any. Study initiated April 8, 2003 and com p leted June 30, 2003. 46203513 Desjardins, D., Kendall, T., and Kr ueger, H. 2003. AE C421200: A 72-Hour Toxicity Test with the Freshwater Alga ( Scenedesmus subspicatus ). Unpublished study perform e d by W ildlife International, Ltd., Easton, Maryland. Laboratory Study No. 149A-160. Study sponsored by Bayer CropScience, Frankfurt am Main, Germ any. Experim e ntal start date May 9, 2003 and experim e ntal term ination date May 12, 2003. The final report issued June 5, 2003. 46203515 Palm er, S.; Kendall, T.; Krueger, H. (2003) AE F132345: A 96-Hour Static Acute Toxicity Test with the Rainbow Trout (O ncorhynchus m ykiss): Final Report. Project Num b er: C032041, 149A/161. Unpublished study prepared by W ildlife International, Ltd. 41 p. 46203516 Palm er, S.; Kendall, T.; Krueger, H. (2003) AE F132345: A 48-Hour Static Acute Toxicity Test with the Cladoceran (Daphnia m a gna). Project Num b er: C032045, 149A/149. Unpublished study prepared by W ildlife International, Ltd. 41 p. 46203517 Desjardins, D., Kendall, T., and Krue ger, H. 2003. AE F132345: A 72-Hour Toxicity Test with the Freshwater Alga ( Scenedesmus subspicatus ). Unpublished study perform e d by W ildlife International, Ltd., Easton, Maryland. Laboratory Study No. 149A-150. Study sponsored by Bayer CropScience, Frankfurt am Main, Germ any. Experim e ntal start date July 28, 2003 and experim e ntal term ination date July 31, 2003. The final report issued August 13, 2003. 46203518 W a ltersdorfer, A. (2002) Contact Toxicity (LD50) to Honey Bees (Apis m e llifera L.) Thidiazuron W a ter Miscible Suspension Concentrate 500 g/l. Project Num b er: C027323, CW 02/046. Unpublished study prepared by Bayer Cropscience Gm bh. 21 p. 46203522 Nienstedt, K. (2003) Thidiazuron, SC 500 G/L: A 14-Day Acute Toxicity Test with the Earthworm Eisenia Fetida. Project Num b er: C031948. Unpublished study prepared by Springborn Laboratories (Europe) Ag. 38 p. 46209601 Myers, D. (2003) AE B049537 (Thidiazur on) Study of Reproductive Perform a nce in Han W i star Rats Treated Continuously Through Two Successive Generations by Dietary Adm i nistration. Project Nu m b er: AES/089, AES/089/024162. Unpublished study prepared by Huntingdon Life Sciences, Ltd. 930 p. 46241001 Kennel, P. (2004) Range-Finding Study for Developm ental Toxicity in the Rabbit by Gavage: (Thidiazuron). Project Num b er: SA/01070, C017597. Unpublished study prepared by Aventis CropScience. 114 p. 46252001 W a son, S. (2004) Historical Control Data: Supplem ent to MRID 46121507:

58Thidiazuron- Developm ental Toxicity Study in the Rabbit by Gavage; Study No. SA 02046. Project Num b er: DAL028/04, SA/02046, B004627. Unpublished study prepared by Bayer CropScience. 25 p. 46261501 Krotlinger, F.; Rosenbruch, M. (2004) Thid iazuron: Subacute Derm al Toxicity Study in Rats (Four W eek Derm al Adm i nistration). Project Num b er: AT01114, T8073134. Unpublished study prepared by Bayer Cropscience LP. 226 p. 46261502 Artus-Jacenko, L. (2004) Thidiazuron: In Vivo Derm al Absorption Study in the Male Rat. Project Num b er: C040234, SA/02427. Unpublished study prepared by Bayer Cropscience. 156 p. 46298401 Norris, F. (2002) Thidiazuron: Magnitude of Residues in Rotational Crops Following Cotton Treated with Dropp. Project Num b er: 00AW 25819, B003793, 25819/02. Unpublished study prepared by Aventis CropScience and South Texas Ag. Research. 248 p. 46298404 W illiam s , L. (2002) Stability of Thidiazuron and its Metabolites 4-Hydroxy Thidiazuron and Phenyl Urea in Milk and Beef Tissues During Frozen Storage, USA, 1995. Project Num b er: AW 95R003, B03987, AW /95R/03. Unpublished study prepared by Bayer CropScience LP. 90 p. 46341001 Mackie, S. (2001) DROPP SC: Magnitude of Residues in Cottonseed and Gin Trash Resulting from Foliar Applications of DROPP SC Under Maxim u m Proposed Label Specifications (2000): Final Study Re port. Project Num b er: 00AW 25588, B003303, AVENTIS/1373. Unpublished study prepared by Pyxant Labs Inc. and Mid South Agric. Research and Stoneville Associates. 336 p. 46345201 Steiblen, G. (2004) Chronic Toxicity a nd Carcinogenicity Study of Thidiazuron in the W i star Rat by Dietary Adm i nistra tion. Project Num b er: SA/01269. Unpublished study prepared by Bayer Cropscience. 2977 p. 46346001 W a son, S. (2004) Carcinogenicity Study of Thidiazuron in the C57BL/6 Mouse by Dietary Adm i nistration. Project Num b er : SA/01333. Unpublished study prepared by Bayer Cropscience. 1687 p. 94246001 Chow, N; Stevens, R. (1990) Nor-Am Chem ical Com p any Phase 3 Sum m a ry of MRID 41364906 and Related MRIDs 00066172, 00066173, 41364901. Physical and Chem ical Characteristics of Thidiazuron. 15 p. 94246026 Guininvan, P.; Stevens, R. (1990) Nor-Am Chem ical Com p any Phase 3 Sum m a ry of MRID 00039332. Determ ination of UL-[ carbon 14]-phenyl-SN49537 Residues in Cotton Plants: Lab. ID NO. PA49537.61/2; M6/2. Prepared by Schering AG. 9 p. 94246027 Guininvan, P.; Stevens, R. (1990) Nor-Am Chem ical Com p any Phase 3 Sum m a ry of MRID 00064749. Residues of SN49537 in Cotton By-Products: Lab. ID No. PA49537.81/6; M8/2. Prepared by Schering AG. 9 p. 94246028 Guininvan, P.; Stevens, R. (1990) Nor-Am Chem ical Com p any Phase 3 Sum m a ry of

59MRID 00064751. Metabolism of Thidiazuron in and on Cotton Plants: Lab. ID No. 49537.81/6; M9/2. Prepared by Schering AG. 8 p. 94246029 Guininvan, P.; Stevens, R. (1990) Nor-Am Chem ical Com p any Phase 3 Sum m a ry of MRID 00039324. Residue Determ ination of SN 49537 in Cottonseed and Cotton Fiber (Prelim . Method) (49537/1): Lab. I.D. No. PA 49537.51/5. Prepared by Schering AG. 13 p. 94246030 Chow, N.; Stevens, R. (1990) Nor-Am Chem ical Com p any Phase 3 Sum m a ry of MRID 40178306. Analytical Method for the Determ ination of Residues of Thidiazuron and Diuron in Cottonseed by Gas Chrom a tography with Electron Capture Detection: Lab. I.D. No. 33001/ A; R47. Prepared by NOR-AM Chem ical Co. 20 p. 94246031 Kelly, U.; Brown, R.; Stevens, R. (1990) Nor-Am Chem ical Com p any Phase 3 Sum m a ry of MRID 00136323 and Related MRIDs 00064747. Residues of Cotton Seed following the Application of DRO PP; R23-R35. Prepared by Agricultural Products, Inc.12 p. 94246033 Guininvan, P.; Stevens, R. (1990) Nor-Am Chem ical Com p any Phase 3 Sum m a ry of MRID 00136323. Residues of Thidiazuron in Cotton By-products following the Application of DROPP: R24, R26-R30, R 32, R33. Prepared by Nor-Am Agricultural Products. 34 p. 94246037 Iwan, J. (1990) Nor-Am Chem ical Com p any Phase 3 Reform at of MRID 00039332. M6/2 Thidiazuron: Determ ination of UL-[carbon 14]-phenyl-SN 49 537 Residues in Cotton Plants: Lab. Project ID: PA 49 537.61/ 2; M6/2. Prepared by Schering AG. 17 p. 94246038 Bruhl, R. (1990) Nor-Am Chem ical Com p any Phase 3 Reform at of MRID 00064749. Thidiazuron: Residues of SN 49 537 in Cotton By-Products: Lab. Project ID: PA 49 537.61/2; M8/2. Prepared by Schering AG. 20 p. 94246039 Bruhl, R. (1990) Nor-Am Chem ical Com p any Phase 3 Reform at of MRID 00064751. Thidiazuron: Metabolism of Thidiazuron in and on Cotton Plants: Lab Project ID: PA 49 537.61/2; M9/2. Prepared by Schering AG. 17 p. 94246040 Scheuerm ann, H. (1990) Nor-Am Chem ical Com p any Phase 3 Reform at of MRID 00039324. Residue Determ ination of SN 49 537 in Cotton Seed and Cotton Fiber (49537/1): Lab. Project ID: PA 49537.51/5; R1/2. Prepared by Schering AG. 19 p. 94246041 Jenny, N. (1990) Nor-Am Chem ical Com p any Phase 3 Reform at of MRID 00136323 and Related MRIDs 00064747. Residues of Thidiazuron in Cotton Seed Following the Application of DROPP: R23-R35. Pr epared by Nor-Am Agricultural Products, Inc. 113 p. 94246042 Jenny, N. (1990) Nor-Am Chem ical Com p any Phase 3 Reform at of MRID 00136323. Residues of Thidiazuron in Cotton By-Products Following the Application of

60DROPP. Prepared by Nor-Am Agricultural Products, Inc. 111 p.

61Appendix E. Generic Data Call-In

62Appendix E. The generic data call-in will be posted at a later date.

63Appendix F. Product Specific Data Call-In

64Appendix F. The product specific data call-in will be posted at a later date.

65Appendix G: Batching
EPA'S BATCHING OF THIDIAZURON PRODUCTS FOR MEETING ACUTE TOXICITY DATA REQUIREMENTS FOR REREGISTRATION
In an ef f o rt to reduce the tim e, resources and num ber of anim als needed to f u lf ill the acute toxicity data requirem e nts for reregistration of products containing Thidiazuron as the active ingredient, the Agency has batched products which can be considered sim ilar for purposes of acute toxicity. Factors considered in the sorting process include each product' s active and inert ingredients (identity, percent com position and bi ological activity), type of form ulation (e.g.,
em ulsifiable concentrate, aerosol, wettable pow der, granular, etc.), and labeling (e.g., signal word, use classification, precautionary labeling, etc. ). Note that the Agency is not describing batched products as "substantially sim ilar" since som e products within a batch m a y not be considered chem ically sim ilar or have identical use patterns. Using available inform ation, batching has been accom p lished by the process described in the preceding paragraph. Notwithstanding the batching process, the Agency reserves the right to require, at any tim e, acute toxicity data for an individual product should the need arise. Registrants of products within a batch m a y choose to cooperatively generate, subm it or cite a single battery of six acute toxicological studies to represent all the products within that batch. It is the registrants' option to participate in the process with all other registrants, only
som e of the other registrants, or only their own products within a batch, or to generate all the required acute toxicological studies for each of th eir own products. If a registrant chooses to generate the data for a batch, he/she m u st use one of the products within the batch as the test
m a terial. If a registrant chooses to rely upon previously subm itted acute toxicity data, he/she
m a y do so provided that the data base is com p lete and valid by today' s standards (see acceptance criteria attached), the form ulation tested is considered by EPA to be sim ilar for acute toxicity, and the form ulation has not been significantly altered since subm ission and acceptance of the acute toxicity data. Regardless of whether new data is generated or existing data is referenced, registrants m u st clearly identif y the test m a teri al by EPA Registration Num b er. If m o re than one confidential statem ent of form ula (CSF) exists for a product, the registrant m u st indicate the form ulation actually tested by identifying the corresponding CSF. In deciding how to m eet the product specific data requirem e nts, registrants m u st follow the directions given in the Data Call-In Notice and its attachm e nts appended to the RED. The DCI Notice contains two response form s which are to be com p leted and subm itted to the Agency within 90 days of receipt. The first form , "Data Call-In Response," asks whether the registrant will m eet the data requirem e nts for each product. The second form , "Requirem e nts Status and Registrant' s Response," lists the product specific data required for each product, including the standard six acute toxicity tests. A registrant who wishes to participate in a batch m u st decide whether he/she will provide the data or depend on som e one else to do so. If a registrant supplies the data to support a batch of products, he/she m u st select one of the following options: Developing Data (Option 1), Subm itting an Exis ting Study (Option 4), Upgrading an Existing

66Study (Option 5) or Citing an Existing Study (Op tion 6). If a registrant depends on another' s data, he/she m u st choose am ong: Cost Sharing (Op tion 2), Offers to Cost Share (Option 3) or Citing an Existing Study (Option 6). If a registrant does not want to participate in a batch, the choices are Options 1, 4, 5 or 6. However, a registrant should know that choosing not to participate in a batch does not preclude other registrants in the batch from citing his/her studies and offering to cost share (Option 3) those studies. Eighteen products were found which contain Thid iazuron as an active ingredient. These products have been placed into four batches and a no batch group in accordance with the active and inert ingredients and type of form ulati on. Furtherm ore, recent decisions by the OPP Registration Division were used to develop this batching approach.

Batch # EPA Reg. No. Percent Active Ingredient
1 51036-402 98.3 72167-28 98.0 73631-4 97.0 2 264-622 50.0 34704-859 50.0 51036-401 50.0 72167-30 50.0 73631-3 50.0 3 264-700 41.0 34704-871 42.4 51036-430 42.4 4 264-634 12.0 34704-872 12.0 51036-429 12.0 72167-47 12.0 No Batch 400-505 8.4 264-821 30.3 264-661 50.0 Appendix H. List of Registrants Sent This Data Call-In

67United States Environmental Protection AgencyWashington, D.C.20460LIST OF ALL REGISTRANTS SENT THIS DATA CALL-IN NOTICECase # and Name:4092,ThidiazuronCo.NumberCompany NameAgent forAddressCity and StateZip264BAYERCROPSCIECNCECROMPTONMANUFACTURINGCOMPANY, INC.LOVELANDPRODUCTS, INC.MICRO-FLOCOMPANY LLCNATIONS AG II,LLCSRM CHEMICAL,LTD. CO.2 T.W.Alexander Drive74 Amity RoadP.O. Box 1286530 Oak Court Drive4680 Monticello Avenue, 181-1741436 Second Street, Suite 331Research Triangle ParkBethanyGreeleyMemphisWilliamsburgNAPANC 27709CT 065243402CO 80632TN 38117VA 23188CA 945584003470451036721677363168Appendix I. List of Available Related Do cuments and Electronically Available Forms Pesticide Registration Forms are available at the follow i ng EPA internet site: http://www.epa.gov/opprd001/form s/. Pesticide Registration Form s (These form s are in PDF form at and require the Acrobat reader)
Instructions
1. Print out and com p lete the form s. (Note: Form num bers that are bolded can be filled out on your com puter then printed.)
2. The com p leted form (s) should be subm itted in hardcopy in accord with the existing policy.
3. Mail the form s, along with any additional docum ents necessary to com p ly with EPA regulations covering your request, to the address below for the Docum e nt Processing Desk.
DO NOT f a x or e-m a il any f o rm containing ' C onf idential Business Inf o rm ation' or ' S ensitive Inform ation.' If you have any problem s accessing these form s, please contact Nicole W illiam s at (703) 308­ 5551 or by e-m a il at william s .nicole@epam a il.epa.gov.
The f o llowing Agency Pesticide Registration Form s are currently available via the internet: at the f o llowing locations:

8570-1 Application for Pesticide Registration/Am endm ent http://www.epa.gov/opprd001/form s/8570-1.pdf.

8570-4 Confidential Statem ent of Form ula http://www.epa.gov/opprd001/form s/8570-4.pdf. 8570-5 Notice of Supplem ental Registration of Distribution of a Registered Pesticide Product http://www.epa.gov/opprd001/form s/8570-5.pdf.

8570-17 Application for an Experim e ntal Use Perm it http://www.epa.gov/opprd001/form s/8570-17.pdf. 8570-25 Application for/Notification of State Registration of a Pesticide To Meet a Special Local Need http://www.epa.gov/opprd001/form s/8570-25.pdf.

8570-27 Form ulator' s Exem ption Statem ent http://www.epa.gov/opprd001/form s/8570-27.pdf. 8570-28 Certification of Com p liance with Data Gap Procedures http://www.epa.gov/opprd001/form s/8570-28.pdf.

8570-30 Pesticide Registration Maintenance Fee Filing http://www.epa.gov/opprd001/form s/8570-30.pdf.

8570-32 Certification of Attem p t to Enter into an Agreem ent with other Registrants for Developm ent of Data http://www.epa.gov/opprd001/form s/8570-32.pdf.

698570-34 Certification with Respect to Citations of Data (in PR Notice 98-5) http://www.epa.gov/opppm sd1/PR_Notices/pr98-5.pdf.

8570-35 Data Matrix (in PR Notice 98-5) h ttp://www.epa.gov/opppm sd1/PR_Notices/pr98-5.pdf. 8570-36 Sum m a ry of the Physical/Chem i cal Properties (in PR Notice 98-1) http://www.epa.gov/opppm sd1/PR_Notices/pr98-1.pdf.

8570-37 Self-Certification Statem ent for the Physical/Chem i cal Properties (in PR Notice 98-1) http://www.epa.gov/opppm sd1/PR_Notices/pr98-1.pdf.

Pesticide Registration Kit www.epa.gov/pesticides/registrationkit/. Dear Registrant: For your convenience, we have assem b led an online registration kit which contains the following pertinent form s and inform ation needed to register a pesticide product with the U.S. Environm ental Protection Agency' s Office of Pesticide Program s (OPP):
1. The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Federal Food, Drug and Cosm etic Act (FFDCA) as Am ended by the Food Quality Protection Act (FQPA) of 1996.
2. Pesticide Registration (PR) Notices

a. 83-3 Label Im provem e nt Program --Storage and Disposal Statem ents b. 84-1 Clarification of Label Im provem e nt Program

c. 86-5 Standard Form at for Data Subm itted under FIFRA d. 87-1 Label Im provem e nt Program for Pesticides Applied through Irrigation System s (Chem i gation)

e. 87-6 Inert Ingredients in Pesticide Products Policy Statem ent f. 90-1 Inert Ingredients in Pesticide Products; Revised Policy Statem ent
g. 95-2 Notifications, Non-notifications, and Minor Form ulation Am endm ents h. 98-1 Self Certification of Product Chem istry Data with Attachm e nts (This docum ent is in PDF form at and requires the Acrobat reader.) Other PR Notices can be found at http://www.epa.gov/opppm sd1/PR_Notices.
3. Pesticide Product Registration Application Form s (These form s are in PDF form at and will require the Acrobat reader.)

a. EPA Form No. 8570-1, Application for Pesticide Registration/Am endm ent

70b. EPA Form No. 8570-4, Confidential Statem ent of Form ula

c. EPA Form No. 8570-27, Form ulator' s Exem ption Statem ent d. EPA Form No. 8570-34, Certification with Respect to Citations of Data

e. EPA Form No. 8570-35, Data Matrix
4. General Pesticide Inf o rm ation (Som e of these f o rm s are in PDF f o rm at and will require the Acrobat reader.)

a. Registration Division Personnel Contact List I. b. Biopesticides and Pollution Prevention Division (BPPD) Contacts

c. Antim icrobials Division Organi zational Structure/Contact List d. 53 F.R. 15952, Pesticide Registration Procedures; Pesticide Data Requirem e nts (PDF form at)

e. 40 CFR Part 156, Labeling Requirem e nts for Pesticides and Devices (PDF form at) f.. 40 CFR Part 158, Data Requirem e nts for Registration (PDF form at)
g.. 50 F.R. 48833, Disclosure of Reviews of Pesticide Data (Novem b er 27, 1985)
Before subm itting your application for registration, you m a y wish to consult som e additional sources of inform ation. These include:
1. The Office of Pesticide Program s' W e b Site
2. The booklet "General Inform ation on Applying for Registration of Pesticides in the United States", PB92-221811, available through the National Technical Inform ation Service (NTIS) at the following address:
National Technical Inform ation Service (NTIS) 5285 Port Royal Road Springfield, VA 22161 The telephone num ber for NTIS is (703) 605-6000.
3. The National Pesticide Inform ation Retrieval System (NPIRS) of Purdue University' s Center for Environm ental and Regulatory Inform ation System s. This service does charge a fee for subscriptions and custom searches. You can contact NPIRS by telephone at (765) 494-6614 or through their W e b site.
4. The National Pesticide Telecom m unications Network (NPTN) can provide inform ation on active ingredients, uses, toxicology, and chem istry of pesticides.

71You can contact NPTN by telephone at (800) 858-7378 or through their W e b site: ace.orst.edu/info/nptn. The Agency will return a notice of receipt of an application for registration or am ended registration, experim e ntal use perm it, or am endm ent to a petition if the applicant or petitioner encloses with his subm ission a stam ped, self -addressed postcard. The postcard m u st contain the following entries to be com p leted by OPP:

• Date of receipt;

• EPA identifying num ber; and

• Product Manager assignm ent. Other identifying inform ation m a y be included by the applicant to link the acknowledgm ent of receipt to the specific application subm itted. EPA will stam p the date of receipt and provide the EPA identifying File Sym bol or petition num ber for the new subm ission. The identifying num ber should be used whenever you contact the Agency concerning an application for registration, experim e ntal use perm it, or tolerance petition. To assist us in ensuring that all data you have subm itted for the chem ical are properly coded and assigned to your com p any, please include a list of all synonym s, com m on and trade nam e s, com p any experim e ntal codes, and other
nam e s which identify the chem ical (including "blind" codes used when a sam p le was subm itted for testing by com m e rcial or academ ic facilities). Please provide a chem ical abstract system (CAS) num ber if one has been assigned.
Documents Associated with this RED The following docum ents are part of the Adm i nistrative Record for this RED docum ent and m a y be included in the EPA' s Office of Pesticide Program s Public Docket. Copies of these docum ents are not available electronically, but m a y be obtained by contacting the person listed on the respective Chem ical Status Sheet.
1. Health Effects Division and Environm ental Fate and Effects Division Science Chapters, which include the com p lete risk assessm ents and supporting docum ents.
2. Detailed Label Usage Inform ation System (LUIS) Report.

72