UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460 

 OFFICE OF 

PREVENTION, PESTICIDES 

AND TOXIC SUBSTANCES 

Date: 13 August 2009

MEMORANDUM

SUBJECT: Clothianidin: Human Health Risk Assessment for Proposed Uses on Berries 

(Group 13-07H), Brassica Vegetables (Group 5), Cotton, Cucurbit Vegetables 

(Group 9), Fig, Fruiting Vegetables (Group 8), Leafy Green Vegetables (Group 

4A), Peach, Pomegranate, Soybean, Tree Nuts (Group 14), and Tuberous and 

Corm Vegetables (Group 1C). 

PC Code: 044309 DP Barcodes: D355373, D362354 

MRID Nos.: See Below Registration Nos.: 59639-150, 59639-151, 

59639-152 

Petition Nos.: 8F7395, 8E7460, 9F7530 Regulatory Action: Section 3 

Assessment Type: Single Chemical Aggregate Registration Case No.: None 

TXR No.: None CAS No.: 210880-92-5 

40 CFR 180.586 Decision Nos.: 397135, 405608 

FROM: Michael A. Doherty, Ph.D., Chemist 

 Alan Levy, Ph.D., Toxicologist 

 Shih-Chi Wang, Ph.D., Biologist 

 Risk Assessment Branch II 

 Health Effects Division (7509P) 

THROUGH: Dennis McNeilly, Chemist 

 Suku Oonnithan, Biologist 

 Linnea Hansen, Ph.D., Toxicologist 

 Richard A. Loranger, Ph.D., Senior Scientist 

 Christina Swartz, Branch Chief 

Risk Assessment Branch II 

Health Effects Division (7509P) 

TO: Kable Davis/Venus Eagle (Team 01) 

 Insecticide/Rodenticide Branch 

 Registration Division (7505P) 

 Barbara Madden 

 Risk Integration, Minor Use & Emergency Response Branch 

 Registration Division (7505P) 

Page 1 of 61 
MRID No. Study Type 

47471601 860.1500 Almond 

47471602 860.1500 Peppers 

47471603 860.1500 Cabbage 

47471604 860.1500 Cantaloupe 

47471605 860.1500 Cauliflower 

47471606 860.1500 Celery 

47471607 860.1500/1520 Cotton 

47471608 860.1500 Cucumber 

47471609 860.1500 Head Lettuce 

47471610 860.1500 Leaf Lettuce 

47471611 860.1500 Mustard Greens 

47471612 860.1500 Pecans 

47471613 860.1500/1520 Soybean 

47471614 860.1500 Spinach 

47471615 860.1500 Summer Squash 

47471616 860.1500/1520 Tomato 

47578101 860.1500 Peach 

47578102 860.1500 Peach 

47578103 860.1500 Cranberry 

47666901 860.1500 Fig 

47666902 860.1500 Pomegranate 

46339001 870.5300 

46339002 870.5300 

46339003 870.5395 

46339004 Non-guideline (Unscheduled DNA Synthesis) 

47506501 Non-guideline (Rat Developmental Immunotoxicity) 

Page 2 of 61 
Table of Contents

1.0 Executive Summary.......................................................................................................... 5 

2.0 Ingredient Profile.............................................................................................................. 7 

2.1 Summary of Registered/Proposed Uses.................................................................. 7 

2.2 Structure and Nomenclature ................................................................................. 10 

2.3 Physical and Chemical Properties......................................................................... 11 

3.0 Hazard Characterization/Assessment........................................................................... 11 

3.1 Hazard and Dose-Response Characterization....................................................... 11 

3.1.1 Database Summary ................................................................................... 11 

3.1.1.1 Studies available and considered (animal, human, general 

literature)................................................................................................... 11 

3.1.1.2 Mode of action, metabolism, toxicokinetic data........................ 11 

3.1.1.3 Sufficiency of studies/data......................................................... 12 

3.1.2 Toxicological Effects................................................................................ 12 

3.1.3 Dose-response........................................................................................... 15 

3.1.4 FQPA ........................................................................................................ 15 

3.2 Absorption, Distribution, Metabolism, Excretion (ADME) ................................. 15 

3.3 FQPA Considerations ........................................................................................... 16 

3.3.1 Adequacy of the Toxicity Database.......................................................... 16 

3.3.2 Evidence of Neurotoxicity ........................................................................ 16 

3.3.3 Developmental Toxicity Studies............................................................... 16 

3.3.4 Reproductive Toxicity Study .................................................................... 17 

3.3.5 Additional Information from Literature Sources ...................................... 17 

3.3.6 Pre-and/or Postnatal Toxicity ................................................................... 17 

3.3.6.1 Determination of Susceptibility ................................................. 17 

3.3.6.2 Degree of Concern Analysis and Residual Uncertainties for Preand/or Postnatal Susceptibility.................................................................. 17 

3.3.7 Recommendation for a Developmental Neurotoxicity Study................... 18 

3.3.8 Rationale for the UFDB.............................................................................. 18 

3.4 Safety Factor for Infants and Children.................................................................. 18 

3.5 Hazard Identification and Toxicity Endpoint Selection........................................ 19 

3.5.1 Acute Reference Dose (aRfD) - Females age 13-49................................. 19 

3.5.2 Acute Reference Dose (aRfD) - General Population................................ 19 

3.5.3 Chronic Reference Dose (cRfD)............................................................... 20 

3.5.4 Incidental Oral Exposure (Short- and Intermediate-Term)....................... 20 

3.5.5 Dermal Absorption.................................................................................... 21 

3.5.6 Dermal Exposure (Short-, Intermediate- and Long-Term)....................... 21 

3.5.7 Inhalation Exposure (Short-, Intermediate- and Long-Term)................... 22 

3.5.8 Level of Concern for Margin of Exposure................................................ 22 

3.5.9 Recommendation for Aggregate Exposure Risk Assessments ................. 22 

3.5.10 Classification of Carcinogenic Potential................................................. 22 

3.5.11 Summary of Toxicological Doses and Endpoints for Use in Human Risk 

Assessments .......................................................................................................... 23 

3.6 Endocrine disruption............................................................................................. 24 

4.0 Public Health and Pesticide Epidemiology Data.......................................................... 25 

5.0 Dietary Exposure/Risk Characterization ..................................................................... 25 

Page 3 of 61 
5.1 Pesticide Metabolism and Environmental Degradation........................................ 25 

5.1.1 Metabolism in Primary Crops................................................................... 25 

5.1.2 Metabolism in Rotational Crops ............................................................... 26 

5.1.3 Metabolism in Livestock........................................................................... 26 

5.1.3 Metabolism in Livestock........................................................................... 26 

5.1.4 Environmental Degradation...................................................................... 26 

5.1.5 Comparative Metabolic Profile................................................................. 26 

5.1.6 Toxicity Profile of Major Metabolites and Degradates ............................ 27 

5.1.7 Pesticide Metabolites and Degradates of Concern.................................... 27 

5.1.8 Analytical Methodology ........................................................................... 28 

5.1.9 Drinking Water Residue Profile................................................................ 28 

5.1.10 Food Residue Profile............................................................................... 29 

5.1.11 International Residue Limits................................................................... 31 

5.2 Dietary Exposure and Risk ................................................................................... 33 

6.0 Residential (Non-Occupational) Exposure/Risk Characterization ............................ 34 

7.0 Aggregate Risk Assessments and Risk Characterization............................................ 35 

7.1 Acute Aggregate Risk........................................................................................... 35 

7.2 Short- and Intermediate-Term Aggregate Risk..................................................... 35 

7.3 Long-Term Aggregate Risk .................................................................................. 35 

7.4 Cancer Risk........................................................................................................... 35 

8.0 Cumulative Risk Characterization/Assessment........................................................... 35 

9.0 Occupational Exposure/Risk Pathway.......................................................................... 36 

9.1 Short- and Intermediate-Term Handler Risk ........................................................ 36 

9.2 Short- and Intermediate-Term Post-Application Risk .......................................... 40 

10.0 Data Needs and Label Recommendations .................................................................... 41 

10.1 Toxicology ............................................................................................................ 41 

10.2 Residue Chemistry................................................................................................ 41 

10.3 Occupational and Residential Exposure ............................................................... 42 

References:................................................................................................................................... 44 

Appendix A: Toxicology Assessment ........................................................................... 45 

A1. Toxicology Data Requirements ............................................................................ 45 

A2. Toxicity Profiles.................................................................................................... 46 

A3. Toxicology Executive Summaries ........................................................................ 55 

Page 4 of 61 
1.0 Executive Summary

Clothianidin, (E)-N-[(2-Chloro-5-thiazolyl)methyl]-N’-methyl-N”-nitroguanidine, is a broad 

spectrum, systemic neonicotinoid insecticide (Group 4A insecticide) and is identical to the major 

metabolite (CGA-322704) of the active ingredient thiamethoxam. Permanent tolerances are 

established for residues of clothianidin in/on various plant and livestock commodities [40 CFR 

§180.586]. Valent has submitted petitions (PP#s 8F7395 and 9F7530) proposing new uses for 

clothianidin formulated as a 50% water-dispersible granule (WDG; Arena® 50 WDG, EPA Reg. 

No. 59639-152) and a 2.13 lb/gal flowable concentrate (FlC; V-1070 2.13 SC, EPA Reg. No 

59639-150) for the control of various insects on the following crops/crop groups: Brassica leafy 

vegetables, cotton, cucurbit vegetables, figs, fruiting vegetables, leafy vegetables, pomegranates, 

soybeans and tree nuts. In addition, Interregional Research Project No. 4 (IR-4) has submitted a 

separate petition (PP#8E7460) proposing new uses for Valent’s 50% WDG and 2.13 lb/gal FlC 

formulations on peaches and members of the low-growing berry (except strawberry) Subgroup 

13-07H. HED has sufficient information to complete a human health risk assessment for these 

requested uses. 

The toxicological database for clothianidin is complete. The available data indicate that there are 

no consistent specific target organs in mammals. The majority of studies show decreases in body 

weights and body weight gains. More severe developmental (missing lobe of the lung in the 

rabbit) and neurological effects in rats and mice are attributable to exposure to clothianidin; these 

effects serve as the basis for acute risk assessments. Effects on body weight gain, delayed sexual 

maturation, decreased thymus weights, and an increase in stillbirths are the basis for assessing 

short-, intermediate-, and/or long-term (chronic) exposures. Based on the completeness of the 

database, the observed effects, and the endpoints used for risk assessment, the FQPA Safety 

Factor has been reduced to 1X, leaving the 100X safety factor to account for within-species 

(10X) and across-species (10X) variability. Clothianidin has been classified as not likely to be 

carcinogenic to humans. 

The submitted residue chemistry data are relatively complete; nevertheless, more data are needed 

in order to recommend for the full suite of requested uses. In spite of the lack of certain data, 

HED is recommending for the establishment of permanent tolerances for all of the requested 

crops; however, label revisions are needed prior to registration and HED is requesting residue 

data comparing soil and foliar applications as a condition of registration. Bridging studies 

examining the effects of adjuvants and different formulations are also being requested. Suitable 

analytical methods are available to enforce tolerances for residues of clothianidin. 

No chemical-specific data for assessing human exposures during pesticide handling or postapplication activities were submitted to the Agency in support of the requested registrations of 

clothianidin. HED used surrogate data from the Pesticide Handler’s Exposure Database (PHED), 

in combination with HED-standard assumptions to assess exposures for crop protection uses. 

The available data are adequate for assessment of exposure to clothianidin, and HED has 

evaluated dietary, non-dietary (i.e., residential/recreational), and occupational risks associated 

with the registered and requested uses of thiamethoxam. For the dietary pathway, thiamethoxam 

has been included as a source of exposure to clothianidin. All of the dietary, non-dietary, and 

Page 5 of 61 
occupational exposure estimates are based on conservative, health-protective assumptions. The 

exposure estimates, especially when combined to take into account aggregate (dietary + nondietary) exposure, may over-estimate actual exposures that are likely to occur. Despite this, all 

risk estimates for clothianidin, including aggregate risk estimates, for all population groups are 

below HED’s level of concern. There are no human health risk issues that preclude establishing 

tolerances and granting the requested registrations for clothianidin for which sufficient data have 

been submitted (see below). 

Summary of Requested Uses Supported by Available Data for Clothianidin 

Supported by Available Data 

Application Formulation 

Requested Use Foliar Soil WDG FlC 

Tank Mix 

Adjuvant 

Berries (Group 13-07H) Yes No Yes No No 

Brassica Vegetables (Group 5) Yes No Yes No No 

Cotton Yes No Yes No No 

Cucurbit Vegetables (Group 9) Yes No Yes No No 

Fruiting Vegetables (Group 8) Yes No Yes No No 

Leafy Green Vegetables (Group 4A) Yes No Yes No No 

Peach Yes No Yes No No 

Soybean Yes No Yes No Yes 

Tree Nuts (Group 14) Yes No Yes No Yes (except almond) 

Tuberous and Corm Vegetables (Group 1C) Yes No Yes No No 

Fig Yes No No Yes Yes 

Pomegranate Yes No No Yes Yes 

Soybean Seed Treatment Yes Yes Not Applicable 

Potato Seed Pieces Seed Treatment Yes Yes Not Applicable 

Human Studies. This risk assessment relies in part on data from studies in which adult human 

subjects were intentionally exposed to a pesticide or other chemical. These studies, which 

comprise the Pesticide Handlers Exposure Database (PHED) & Agricultural Re-Entry Task 

Force (ARTF), have been determined to require a review of their ethical conduct, and have 

received that review. The studies in PHED and ARTF were considered appropriate (or ethically 

conducted) for use in risk assessments. 

Environmental Justice Considerations. Potential areas of environmental justice concerns, to the 

extent possible, were considered in this human health risk assessment, in accordance with U.S. 

Executive Order 12898, "Federal Actions to Address Environmental Justice in Minority 

Populations and Low-Income Populations," 

(http://www.eh.doe.gov/oepa/guidance/justice/eo12898.pdf). 

As a part of every pesticide risk assessment, OPP considers a large variety of consumer 

subgroups according to well-established procedures. In line with OPP policy, HED estimates 

risks to population subgroups from pesticide exposures that are based on patterns of that 

subgroup’s food and water consumption, and activities in and around the home that involve 

pesticide use in a residential setting. Extensive data on food consumption patterns are compiled 

by the USDA under the Continuing Survey of Food Intake by Individuals (CSFII) and are used 

in pesticide risk assessments for all registered food uses of a pesticide. These data are analyzed 

and categorized by subgroups based on age, season of the year, ethnic group, and region of the 

country. Additionally, OPP is able to assess dietary exposure to smaller, specialized subgroups 

Page 6 of 61 
and exposure assessments are performed when conditions or circumstances warrant. Whenever 

appropriate, non-dietary exposures based on home use of pesticide products and associated risks 

for adult applicators and for toddlers, youths, and adults entering or playing on treated areas 

postapplication are evaluated. Further considerations are currently in development as OPP has 

committed resources and expertise to the development of specialized software and models that 

consider exposure to bystanders and farm workers as well as lifestyle and traditional dietary 

patterns among specific subgroups. 

Provided the label revisions and revised Section F detailed in Section 10.2 are submitted, HED 

recommends for the requested soybean and potato seed treatments, for foliar uses as detailed in 

the preceding table, and for the tolerances detailed in Table 10. 

2.0 Ingredient Profile

Clothianidin is a broad spectrum, systemic insecticide belonging to both the chloronicotinyl 

(neonicotinoid) and nitroguanidine classes of chemicals. It is also a major metabolite of 

thiamethoxam. Clothianidin acts by binding with the nicotinic acetylcholine receptor sites in 

insects (Group 4A insecticide), interfering with neural transmission of stimuli and eventually 

inhibiting reproduction of the insect. Clothianidin Technical Insecticide was first registered in 

the U.S. during 2003 by Takeda, with Bayer CropScience (Bayer) acting as their Agent. Bayer 

currently has six end-use products containing clothianidin that are registered only for seed 

treatment uses on corn, canola, cotton, rapeseed, and sorghum. Clothianidin end-use products 

with direct foliar and/or soil uses on grapes, pome fruits, potatoes and tobacco were originally 

registered to Arvesta (now known as Arysta). However, these products/uses have been 

transferred to Valent, which is now the Agent for Sumitomo Chemical Co. which owns the 

current registration for Technical Clothianidin. The chemical structure and nomenclature of 

clothianidin and its metabolite, TMG, are listed in Table 2.2, and the physicochemical properties 

of technical grade clothianidin are listed in Table 2.3. 

2.1 Summary of Registered/Proposed Uses

Permanent tolerances are established for residues of clothianidin in/on a variety of plant 

commodities at levels ranging from 0.01 ppm in/on a number of crops to 1.0 ppm in/on pome 

fruits [40 CFR §180.586(a)]. Tolerances for clothianidin have also been established in milk at 

0.01 ppm. Time-limited tolerances have been established at 0.02 ppm in/on sugar beet roots and 

tops [40 CFR §180.586(b)]; these tolerances are set to expire on 12/31/09. In addition, 

tolerances for indirect or inadvertent residues have been established for clothianidin at 0.02 ppm 

in/on non-grass animal feeds, the forage, fodder and straw of cereal grains, grass forage, fodder 

and hay, and soybean forage and hay [40 CFR §180.586(d)]. 

Valent has submitted petitions (PP#s 8F7395 and 9F7530) proposing new uses for its 50% WDG 

and 2.13 lb/gal FlC formulations on Brassica leafy vegetables, cotton, cucurbit vegetables, figs, 

fruiting vegetables, leafy vegetables, pomegranates, soybeans and tree nuts. Valent is also 

proposing to amend the use directions for its 5 lb/gal FlC formulation to include a seed treatment 

use on potato seed pieces and soybean seeds. In addition, IR-4 has submitted a separate petition 

(PP#8E7460) proposing new uses for Valent’s 50% WDG and 2.13 lb/gal FlC formulations on 

Page 7 of 61 
peaches and members of the low-growing berries subgroup, except strawberry (Subgroup 13-

07H). IR-4 is also proposing that the current use directions for potatoes on the labels for the 

50% WDG and 2.13 lb/gal FlC be amended to cover all tuberous and corm vegetables (Subgroup 

1C). The use patterns associated with the requested uses are summarized in Table 2.1. 

Table 2.1. Summary of Proposed Directions for Use of Clothianidin. 

Applic. Timing, Type, and 

Equip.1 

Formulation 

[EPA Reg. No.] 

Applic. Rate 

(lb ai/A) 

Max. No. 

Applic. 

per 

Season 

Max. 

Seasonal 

Applic. Rate 

(lb ai/A) 

PHI 

(days) Use Directions and Limitations 2 

Brassica Vegetables, Leafy Vegetables, Cucurbit Vegetables, and Fruiting Vegetables 

Soil application at planting or 

post-planting 3

; ground 

equipment 

0.2 1 0.2 7 

Broadcast foliar applications as 

pest populations begin to build; 

ground equipment 

50% WDG 

[59639-152] 

2.13 lb/gal FlC 

[59639-150] 0.05-0.067 NS 0.2 7 

The minimum RTI for foliar 

applications is 10 days. 

A minimum application volume is 

not specified. 

Cotton 

Broadcast foliar applications as 

pest populations reach 

threshold levels; ground 

equipment 

50% WDG 

[59639-152] 

2.13 lbs/gal FlC 

[59639-150] 

0.05-0.067 NS 0.2 21 

The minimum RTI is 7 days. 

A minimum application volume is 

not specified. 

Low Growing Berries, except Strawberry (Subgroup 13-07H) 

Single post-bloom soil 

application as pest populations 

reach threshold levels; ground 

equipment 

0.2 1 21 

Post-bloom broadcast foliar 

applications as pest populations 

reach threshold levels; ground 

equipment 

50% WDG 

[59639-152] 

2.13 lbs/gal FlC 

[59639-150] 

0.066 NS 

0.2 

21 

The minimum RTI is 7 days for 

foliar applications. 

A minimum application volume is 

not specified. 

Fig 

Post-bloom broadcast foliar 

applications as pest populations 

reach threshold levels; ground 

equipment 

50% WDG 

[59639-152] 

2.13 lbs/gal FlC 

[59639-150] 

0.06-0.09 2 0.2 7 

The minimum RTI is 14 days. 

Apply in a minimum of 100 gal/A. 

Do not allow livestock to graze on 

cover crops from treated orchards. 

Pomegranate 

Post-bloom broadcast foliar 

applications as pest populations 

reach threshold levels; ground 

equipment 

50% WDG 

[59639-152] 

2.13 lbs/gal FlC 

[59639-150] 

0.06-0.09 2 0.2 7 

The minimum RTI is 14 days. 

Apply in a minimum of 100 gal/A. 

Do not allow livestock to graze on 

cover crops from treated orchards. 

Peach

Post-bloom broadcast foliar 

applications as pest populations 

reach threshold levels; ground 

equipment 

50% WDG 

[59639-152] 

2.13 lbs/gal FlC 

[59639-150] 

0.05-0.1 NS 0.2 7 

The minimum RTI is 10 days. 

A minimum application volume is 

not specified. 

Do not allow livestock to graze on 

cover crops from treated orchards. 

Page 8 of 61 
Table 2.1. Summary of Proposed Directions for Use of Clothianidin. 

Applic. Timing, Type, and 

Equip.1 

Formulation 

[EPA Reg. No.] 

Applic. Rate 

(lb ai/A) 

Max. No. 

Applic. 

per 

Season 

Max. 

Seasonal 

Applic. Rate 

(lb ai/A) 

PHI 

(days) Use Directions and Limitations 2 

Potato/ Tuber and Corm Vegetables, Subgroup 1C 4

Seed-piece treatment; spray 5 lb/gal FlC 

[59639-151] 

2.13 lb/gal FlC 

[59639-150] 

0.01 lb ai/ 100 

lb seed pieces 

(0.2 lb ai/A) 5 

1 0.2 NA 

Do not use treated seed pieces for 

food, feed, or fodder. 

Do not apply any subsequent 

application of clothianidin 

following seed piece treatment. 

In-furrow soil application at 

planting, or side-dress or 

broadcast soil application at 

ground-crack during hilling; 

ground equipment 

0.12-0.19 1 0.2 NA 

Broadcast foliar applications as 

pest populations reach 

threshold levels; ground 

equipment 

50% WDG 

[59639-152] 

2.13 lbs/gal FlC 

[59639-150] 

0.03-0.05 3 0.2 14 

The minimum RTI for foliar 

applications is 7 days. 

A minimum application volume is 

not specified. 

Soybean 

Seed Treatment, commercial 

seed treatment equipment 5 lb/gal FlC 

[59639-151] 

0.05 lb ai/ 

100 lb seed 

(0.05 lb ai/A) 6 

1 0.05 NA 

Do not use treated seed for feed, 

food or oil processing. 

Broadcast foliar applications as 

pest populations reach 

threshold levels; ground 

equipment 

50% WDG 

[59639-152] 

2.13 lb/gal FlC 

[59639-150] 

0.05-0.067 NS 0.2 21 

The minimum RTI for foliar 

applications is 7 days. 

A minimum application volume is 

not specified. 

Do not apply foliar applications 

following a seed treatment with 

clothianidin 

Tree Nuts 

Broadcast foliar or chemigation 

applications at post bloom; 

ground equipment 

50% WDG 

[59639-152] 

2.13 lb/gal FlC 

[59639-150] 

0.05-0.10 NS 0.2 21 

The minimum RTI is 10 days. 

A minimum application volume is 

not specified. 

Do not allow livestock to graze on 

cover crops from treated orchards. 1

 Do not apply by air. Applications are allowed through the following types of irrigations systems: micro (spaghetti tubes), 

drip, and overhead sprinklers (center pivot, solid set, hand move or moving wheel systems). Do not apply through any 

irrigation system connected to the public water system. Applications may include use of a spray adjuvant. 2 A 12-hour restricted entry interval is specified. Do not apply to vegetable, fruit or tree nut crops during pre-bloom, bloom or 

when bees are actively foraging. For all crops, do not apply a foliar application of clothianidin following a soil application; 

and do not apply more than 0.2 lb ai/A of clothianidin per season. 3 Soil applications can be made as either a narrow band centered on the plant row, an in-furrow spray at planting on or below the

seed, a side-dress application to both sides of the row, a post-seeding drench or transplant water drench, or by chemigation into 

the root zone through drip, trickle, or micro-sprinkler systems. 4

 The uses of the 50% WDG and 2.13 lb/gal FlC formulations on potatoes were previously approved under PP#4F6869 (DP# 

D303164, W. Drew, 2/1/06). 5

 The use rate per acre for the potato seed piece treatment is based on a planting rate of 2,000 lb of seed pieces/acre. 6

 The worst-case use rate per acre for the soybean seed treatment assumes a high planting density (200,000 plants/A) and use of 

larger seeds (2,000 seed/lb), which would require 100 lb of seed/A. A more typical planting density of 160,000 seed/A using 

average sized seed (3,000 seed/lb) would result in a use rate of 0.026 lb ai/A. 

NA = Not applicable. 

NS = not specified. 

Page 9 of 61 
2.2 Structure and Nomenclature

The chemical structure and nomenclature of clothianidin and its TMG metabolite are 

summarized in Table 2.2. Physical/chemical properties for clothianidin are summarized in Table 

2.3. Based on the available data, clothianidin has a very low vapor pressure and exposure to this 

chemical in the vapor phase is not expected. The octanol/water partitioning coefficient is also 

quite low, indicating that clothianidin is unlikely to accumulate in fatty tissues. 

Table 2.2. Clothianidin Nomenclature.

Parent Compound 

S

N

N

H

N

NH

Cl

3CH

NO2

Common name Clothianidin 

Company experimental name TI-435, V-10066 

IUPAC name (E)-1-(2-Chloro-1,3-thiazol-5-ylmethyl)-3-methyl-2-nitroguanidine 

CAS name (E)-N-[(2-Chloro-5-thiazolyl)methyl]-N’-methyl-N”-nitroguanidine 

CAS registry number 210880-92-5 (formerly 205510-53-8) 

Molecular wt. 249.68 

End-use product (EP) 50% WDG (Arena® 50 WDG; EPA Reg. No. 59639-152) 

2.13 lb/gal FlC (V-10170 2.13 SC; EPA Reg. No. 59639-150) 

5 lb/gal FlC (V-10170 5 FS; EPA Reg. No. 59639-151) 

Metabolite 

S

N

N

H

NH

NH

Cl

3

CH

Common name Thiazolylmethylguanidine 

Company experimental name TMG 

IUPAC name N-(2-chlorothiazol-5-yl)-N ́-methylguanidine 

CAS Name N-(2-chlorothiazol-5-yl)-N ́-methylguanidine 

CAS registry number 635283-91-9 

Molecular wt. 204.68 

Page 10 of 61 
2.3 Physical and Chemical Properties

Table 2.3. Physicochemical Properties of Clothianidin.

Parameter Value Reference 

Melting point (oC) 176.8 

pH at 23oC 6.24 (1% solution/suspension) 

Density (g/cm3) 1.61 (PAI)*, 1.59 (TGAI) 

Water solubility (g/L at 20oC) 0.327 

Solvent solubility (g/L at 25oC) Acetone 15.2 Dichloromethane 1.32 

Ethyl acetate 2.03 Heptane <0.00104 

Methanol 6.26 Octanol 0.938 

Xylene 0.0128 

Vapor pressure (Pa at 20oC) 1.3 x 10 -10

Dissociation constant, pKa at 20oC 11.09 

Octanol/water partition 

coefficient, Log(KOW) at 25oC 

0.7 

UV/visible absorption spectrum 

(Maximum, nm) 

265.5 (acidic or neutral) 

246.0 (basic) 

D335355, W. Drew, 

10/16/07

*PAI = Purified Active Ingredient; TGAI = technical grade active ingredient. 

3.0 Hazard Characterization/Assessment

3.1 Hazard and Dose-Response Characterization

3.1.1 Database Summary

The toxicological database for clothianidin is complete. The scientific quality is relatively high 

and the toxicity profile of clothianidin can be characterized for most effects, including potential 

carcinogenic, mutagenic, developmental and reproductive, neurotoxic and immunotoxic effects. 

Since the last risk assessment for clothianidin, the Agency has received and reviewed a 

developmental immunotoxicity study and four mutagenicity studies (see Appendix A3). 

3.1.1.1 Studies available and considered (animal, human, general literature) 

The following studies were submitted: acute and subchronic neurotoxicity; subchronic in rats, 

mice and dogs; subchronic dermal, chronic/carcinogenicity in rats; carcinogenicity in mice; 

chronic in dogs; developmental in rats and rabbits; developmental neurotoxicity; reproduction; 

mutagenicity battery; metabolism (rats and mice); dermal penetration (monkeys) and 

immunotoxicity as well as developmental immunotoxicity. 

3.1.1.2 Mode of action, metabolism, toxicokinetic data

Clothianidin is a major metabolite of the active ingredient thiamethoxam and is a systemic 

insecticide that belongs to the nitroguanidine sub-class of neonicotinoid compounds, which have 

agonistic activity on nicotinergic acetylcholine receptors (nAChR). It enters through the roots 

and cotyledons of newly germinating seedlings and protects below- and above-ground plant parts 

from insect damage. 

Page 11 of 61 
In rats, clothianidin was readily absorbed and excreted within 96 hours following a single or 

repeated low doses, but at a high dose, absorption became biphasic and was saturated. The 

studies suggest that a multiple exposure regimen did not affect the absorption/excretion 

processes. There was rapid absorption and distribution of administered radioactivity to all 

organs and tissues followed by rapid excretion primarily via the urine (>89% of dose) and to a 

lesser extent, the feces, with reduction to background levels in most tissues and organs within 24 

hours. There was a somewhat greater rate of absorption and elimination in females. Excretory 

patterns did not exhibit gender-related variability but reflected the delayed absorption in the 

high-dose group. The metabolites identified (primarily oxidative demethylation products and 

cleavage products of the nitrogen-carbon bond between the nitroimino and thiazolyl moieties) 

were consistent with Phase I processes of oxidation, reduction and hydrolysis. 

 

In mice, clothianidin was readily absorbed and excreted within 168 hours following a single low 

dose. Urine was the major route of excretion. Neither clothianidin nor its metabolites appeared 

to exhibit potential for bioaccumulation. Excretory patterns did not exhibit gender-related 

variability. The major metabolites in both urine and feces were the parent compound 

(clothianidin) and TZNG [N-(2-chlorothiazol-5-ylmethyl)-N’-nitroguanidine], which resulted 

from N-demethylation of clothianidin. 

3.1.1.3 Sufficiency of studies/data

Data are sufficient for FQPA evaluation, toxicity endpoint selection and dose-response 

evaluation. 

3.1.2 Toxicological Effects

Clothianidin and its metabolites have relatively low (Category III or IV) acute toxicity via oral, 

inhalation and dermal routes of exposure in the rat and there is no evidence of dermal 

sensitization or eye irritation with the exception of the clothianidin-triazan intermediate, which is 

a dermal sensitizer. The other exceptions were for technical clothianidin and the TMG 

metabolite via the oral route in the rat both of which were toxicity Category II. 

Clothianidin induces some effects that are similar to other neonicotinoid insecticides, particularly 

on the liver, hematopoietic system and kidneys. 

Acute neurotoxicity studies were conducted in rats and mice following exposure by gavage. 

Comparing these two studies, mice appear to be more sensitive than rats. In the acute 

neurotoxicity rat study, FOB effects, including decreased arousal as well as decreased motor and 

locomotor activity, were seen at the LOAEL on Day 0 in males. Effects at dose levels above the 

LOAEL in the rat study included tremors, slightly uncoordinated gait, effects on pupil response 

and righting reflex, and decreases in both temperature and ataxia. In the acute neurotoxicity 

study in mice, effects were also observed on Day 0 in males (no female mice were tested), but 

they occurred at lower doses than those that produced neurotoxic effects in rats. Effects seen at 

the LOAEL in this mouse study included transient signs of decreased spontaneous motor 

activity, tremors and deep respirations. At higher dose levels, the following were observed: 

Page 12 of 61 
decreases in reactivity, grooming and muscle tone; prone position; staggering gait; mydriasis; 

and hypothermia. 

In rats only, a subchronic neurotoxicity study was conducted following dietary exposure. In 

contrast to the acute neurotoxicity study described previously, no indications of neurotoxicity 

were noted in the subchronic study. Slightly decreased food consumption, body weights and 

body weight gains were the only observed effects. 

In subchronic oral studies in rats and dogs, decreases in body weight and body weight gain were 

observed. In addition, dogs also displayed decreased white blood cells, albumin and total 

protein, as well as some anemia, and they appeared to be more sensitive than rats. Male dogs 

were more sensitive than females. No effects were observed up to the limit dose in the 28-day 

dermal study in rats. 

Chronic feeding studies were conducted in the dog, rat and mouse. Anemia was observed in the 

dog. In the rat, decreased body weight and food consumption, interstitial gland hyperplasia in 

the ovary, increased lymphohistiocytic infiltrate and altered hepatocellular eosinophilic foci of 

the liver were observed in females; decreased body weight and food consumption, slightly 

increased incidences of pelvic mineralization, and transitional cell hyperplasia in the kidney, 

mottled livers, and altered hepatocellular eosinophilic foci in the liver were observed in male 

rats. In the mouse, decreases in body weight and body weight gain in females and increases in 

vocalization in both sexes were the only observed effects. Anemia, only in females, was 

observed at the highest dose tested in dogs. 

A comparison of the subchronic and chronic feeding studies in rats showed that a wider spectrum 

of effects was observed in the chronic study, even though the NOAELs and LOAELs in these 

two studies were similar. Thus, it appears that there may be more toxicity in rats when exposure 

is over a longer period of time. In contrast, administration to the dog for a longer period of time 

does not appear to result in any additional effects or effects at lower doses. 

There was an increase in quantitative susceptibility in the developmental neurotoxicity study. 

Effects in the offspring were observed at a lower dose than the dose which caused toxicity in the 

maternal animals. However, this increased susceptibility does not require an additional 10X 

uncertainty factor because endpoints selected for assessment of risks to infants and children are 

at doses below the offspring NOAEL observed in this study and thus are protective of these 

effects. Maternal effects included decreased body weights, body weight gains and food 

consumption. Effects seen in the offspring included decreased body weights, body weight gains, 

motor activity and acoustic startle response in females. 

No increased quantitative or qualitative susceptibility was observed in the developmental rat or 

rabbit studies. In the rat, no developmental toxicity was observed at the highest dose tested, 

although this dose induced decreases in body weight gain and food consumption in the dams. In 

the rabbit, premature deliveries, decreased gravid uterine weights, an increase in litter incidence 

of a missing lobe of the lung and a decrease in the litter average for ossified sternal centra per 

fetus were noted at a dose level at which maternal death, a decrease in food consumption and 

clinical signs (scant feces and orange urine) were observed. The developmental effects in this 

Page 13 of 61 
study are not considered to be quantitatively more severe than the maternal effects because they 

occurred at the same dose and they are not considered to be qualitatively more severe because 

death occurred in the dams. 

Increased quantitative susceptibility was observed in the two-generation reproduction study since 

the offspring NOAEL was lower than the parental NOAEL. The LOAEL for offspring toxicity 

is based on decreased body weight gains, delayed sexual maturation (males), decreased absolute 

thymus weights in F1 pups of both sexes, and an increase in stillbirths in both generations. The 

parental systemic LOAEL is based on decreased absolute body weights and body weight gains 

with decreased absolute and relative thymus weights in both sexes. 

In the rat chronic carcinogenicity study, an apparent increase in thyroid c-cell tumors was 

observed in females. A statistical analysis revealed that the increase in these tumors did not 

appear to be significant, especially when carcinomas and adenomas were combined. An 

increased incidence of hepatocellular carcinomas at the low and high doses were just outside 

historical control incidences for the same testing laboratory (only 2 studies) but were within the 

historical control range for the animal supplier. In addition, there was no dose-response. Also, 

there was no continuum (i.e., no preneoplastic lesions and no adenomas). There was no evidence 

of an increase of tumors in mice. Therefore, clothianidin is classified as not likely to be 

carcinogenic to humans. 

 

In the mutagenicity studies, none of the intermediates or metabolites appeared to have genotoxic 

potential under the conditions of the studies, but the studies for the technical material gave mixed 

results. Some of the batches of test material were positive and some were negative. HED had 

requested that the composition of the test materials used in the mutagenicity studies be 

investigated to determine whether or not the differences in composition may have affected the 

results from the studies. To address the request, additional mutagenicity studies were performed 

and it was determined that there was no concern because clothianidin was neither clastogenic nor 

aneugenic in the mouse bone marrow micronucleus assay up to a toxic oral dose (100 mg/kg); 

also, there was no induction of unscheduled DNA synthesis (UDS) in the livers of Wistar male 

mice when administered at the limit dose of 2000 mg/kg. 

In some of the toxicity studies, there was evidence of possible effects on the immune system. 

Decreased absolute and relative thymus and spleen weights were observed in multiple studies. 

In addition, juvenile rats in the two-generation reproduction study appeared to be more 

susceptible to these effects. The thymus is involved in the production of T cells, whose function 

is to recognize and respond to foreign antigens. The spleen serves an important function in 

clearing the blood of infectious organisms. A guideline immunotoxicity study showed no 

evidence of clothianidin-mediated immunotoxicity in adult rats, in the form of a T-cell dependent 

anti-Sheep Red Blood Cell (SRBC) forming cell response, at doses lower than those resulting in 

generalized signs of toxicity (e.g., decreases in body weight). However, since effect in the 

offspring occurred at lower doses in the two-generation study, HED concluded that the lack of 

effects on immunotoxicity in adults did not alleviate concerns for immunotoxicity in the 

offspring. A developmental immunotoxicity study was required and demonstrated no 

susceptibility with respect to immunotoxicity. 

Page 14 of 61 
In a dermal absorption study in monkeys, absorption was calculated as 0.24% (±0.11%). This 

value was determined by adding the radioactivity recovered from urinary excretion, fecal 

excretion and from cage/pan/chair wash debris. Adjustment of the direct absorption 

determination was not necessary because recovery from the dermal dose was >90%. A value of 

1% dermal absorption has been recommended as appropriate for use in risk assessment. This 

estimation takes into account any variability that would have likely occurred with testing several 

dose levels. The mouse single dose and rat single and multiple dose metabolism studies 

indicated that oral absorption was in the range of 90% or greater. Therefore, any extrapolation 

from the oral to the dermal route using the dermal absorption factor is not likely to underestimate 

anticipated adverse effects. 

3.1.3 Dose-response

The database on clothianidin indicates no consistent specific target organs at the doses tested. 

Decreases in body weights and body weight gains were consistently observed among species and 

at different dosing durations. Clinical signs of neurotoxicity were exhibited in both rats and mice 

in the single dose (gavage) studies; however, no indications of neurotoxicity were observed in 

the subchronic (dietary) rat study. In a developmental neurotoxicity study in rats, decreased 

body weights, body weight gains, motor activity and acoustic startle response amplitude 

(females) were seen in offspring at doses lower than those resulting in maternal toxicity. 

Although the NOAELs were similar for the subchronic and chronic feeding studies in the rat, a 

greater spectrum of effects was observed in the chronic study. Dogs dosed for 3 months or 1 

year exhibited clinical signs of anemia. The only observed effects in mice following chronic 

dietary administration were increases in vocalization and decreases in body weight and body 

weight gains. There was no evidence of increased quantitative or qualitative susceptibility of rat 

or rabbit fetuses in developmental studies; however, increased quantitative susceptibility of rat 

pups was seen in both the reproduction and developmental neurotoxicity studies. The degree of 

concern for both of these studies is low because the observed effects are well characterized and 

there are clear NOAELs. 

3.1.4 FQPA 

See Sections 3.3 and 3.4. 

3.2 Absorption, Distribution, Metabolism, Excretion (ADME)

In rats, clothianidin was readily absorbed and excreted within 96 hours. Females showed a 

greater rate of absorption. Metabolites were primarily oxidative demethylation and cleavage 

products. 

In mice, absorption and excretion were complete within 168 hours with urine as the major 

excretory route. No bioaccumulation was apparent. Parent and TZNG metabolite were noted in 

urine and feces. 

A dermal absorption study in the monkey indicated that absorption was 0.24%. 

Page 15 of 61 
3.3 FQPA Considerations

3.3.1 Adequacy of the Toxicity Database

The database for evaluating in utero or postnatal susceptibility is adequate for evaluation of the 

FQPA safety factor. The following acceptable studies are available: 

 Developmental toxicity studies in rats and rabbits 

 Two-generation reproduction study in rats 

 Developmental neurotoxicity study in rats 

 Developmental immunotoxicity study in rats 

3.3.2 Evidence of Neurotoxicity

Clothianidin was tested in the following three rat neurotoxicity studies: acute, 90-day and 

developmental. In addition, a neurotoxicity/pharmacology single dose study was performed in 

mice. 

In the acute neurotoxicity study, decreased arousal, motor activity and locomotor activity were 

observed; however, in the subchronic study, the LOAEL was based on decreased body weights, 

body weight gains and food consumption with no evidence of neurotoxicity. 

In the developmental neurotoxicity study, the maternal effects included decreased body weights, 

body weight gains and food consumption; whereas, in the offspring, decreased body weights, 

body weight gains, motor activity and acoustic startle response in females were observed at a 

lower dose than the dose required to induce effects in the dams. 

In the single dose mouse study, transient signs of decreased spontaneous motor activity, tremors 

and deep respirations were observed. 

No signs of neurotoxicity were observed in the remainder of the toxicity studies. 

3.3.3 Developmental Toxicity Studies

In the gavage developmental studies, there is no evidence of increased quantitative or qualitative 

susceptibility of rat or rabbit fetuses to in utero exposure to clothianidin. The developmental 

NOAELs are either higher than or equal to the maternal NOAELs. The toxicological effects in 

fetuses are not considered to be more severe than those in the dams or does. 

In the rat developmental neurotoxicity study, there was evidence of increased quantitative 

susceptibility, because offspring effects were observed at lower doses than doses at which 

maternal effects were observed; however, the effects were not considered to be more severe. 

The maternal NOAEL was 43 mg/kg/day with the LOAEL being 142 mg/kg/day based on 

decreased body weight, body weight gain and food consumption. For offspring, the NOAEL 

was 13 mg/kg/day and the LOAEL was 43 mg/kg/day based on decreases in body weights, body 

Page 16 of 61 
weight gains, motor activity and acoustic startle response in females. Nonetheless, HED 

considers the degree of concern for the developmental neurotoxicity study to be low and there 

are no residual uncertainties for pre- and/or postnatal toxicity because the observed effects are 

well characterized and there are clear NOAELs/LOAELs. 

3.3.4 Reproductive Toxicity Study

Increased quantitative susceptibility was observed in the two-generation reproduction study, in 

which offspring toxicity (decreased body weight gains, delayed sexual maturation in males, 

decreased absolute thymus weights in F1 pups of both sexes and an increase in stillbirths in both 

generations) was seen at a dose lower than that which caused parental toxicity consisting of 

decreased body weight gains as well as decreased thymus weights (absolute and relative). 

3.3.5 Additional Information from Literature Sources

None. 

3.3.6 Pre-and/or Postnatal Toxicity

3.3.6.1 Determination of Susceptibility

While no increased quantitative or qualitative susceptibility was observed in either of the 

developmental rat or rabbit studies, increased quantitative susceptibility was observed in both the 

developmental neurotoxicity and rat reproduction studies. In the developmental neurotoxicity 

study, offspring toxicity (decreased body weight gains, motor activity and acoustic startle 

response) was seen at a lower dose than the dose what caused maternal toxicity. However, HED 

determined that the degree of concern for the developmental neurotoxicity study is low and there 

are no residual uncertainties for pre- and/or postnatal toxicity because the observed effects are 

well characterized and there are clear NOAELs/LOAELs. 

In the two-generation reproduction study, offspring toxicity (decreased body weight gains, 

delayed sexual maturation in males, decreased absolute thymus weights in F1 pups of both sexes 

and an increase in stillbirths in both generations) was seen at a dose lower than that which caused 

parental toxicity. 

Immunotoxicity and developmental immunotoxicity studies were performed and neither showed 

any changes in the immune system parameters examined. 

3.3.6.2 Degree of Concern Analysis and Residual Uncertainties for Pre- and/or Postnatal 

Susceptibility 

There is low concern for an increase in quantitative or qualitative susceptibility in rats or rabbits 

in the developmental studies. In the rat study, no developmental effects were noted in the 

highest dose tested; whereas, there was a decrease in maternal body weights and body weight 

gains as well as food consumption. In the rabbit developmental study, maternal death occurred 

as the same dose as the fetal findings. In the rat developmental neurotoxicity study, although 

Page 17 of 61 
there were neurotoxic signs in the offspring (decreased motor activity and acoustic startle 

response in females) at a dose lower than the maternal effects, the degree of these findings was 

considered to be minor and there would be little or no concern because the doses selected for risk 

assessment are protective of the effects observed in the developmental neurotoxicity study. 

In the two-generation reproduction study, the offspring NOAEL (based on LOAEL findings of 

delayed sexual maturation in F1 males and an increase in stillbirth in both generations) was at a 

dose lower than the parental NOAEL (based on decreased body weights, body weight gains and 

thymus weights). There was an increased quantitative susceptibility in this study, but the degree 

of concern is low because the study NOAEL and LOAEL have been selected for risk assessment 

purposes for relevant exposure routes and durations. In addition, the potential immunotoxic 

effects observed in the study have been further characterized with the submission of a 

developmental immunotoxicity study, which showed no evidence of susceptibility. 

3.3.7 Recommendation for a Developmental Neurotoxicity Study

A developmental neurotoxicity study was submitted and reviewed by the Agency (see Section 

3.3.2). 

3.3.8 Rationale for the UFDB (when a DNT is recommended)

No database uncertainty factor is required (see Section 3.3.2) 

3.4 FQPA Safety Factor for Infants and Children 

It is recommended that the 10X FQPA safety factor for the protection of infants and children be 

reduced to 1X. There is no increased qualitative or quantitative susceptibility in the rat or rabbit 

developmental toxicity studies. In the rat developmental neurotoxicity study, there was evidence 

of quantitative susceptibility, but the NOAEL and LOAEL were well characterized and the doses 

and endpoints selected for risk assessment are protective of the observed susceptibility. 

In the two-generation reproduction study, there was increased quantitative susceptibility as the 

offspring NOAEL was below the parental NOAEL. There was a clear difference between the 

NOAEL and the LOAEL. The observed susceptibility in the reproduction study and the 

potential immunotoxicity observed in the study was the basis for the retention of a 10X database 

uncertainty factor (UFDB) for the lack of the developmental immunotoxicity study in previous 

risk assessments. However, the submitted developmental immunotoxicity study demonstrated no 

treatment-related effects. 

With the submission of an acceptable immunotoxicity study, HED has concluded the 10X FQPA 

safety factor can be removed (reduced to 1X). The toxicity database is complete; despite 

evidence of quantitative susceptibility in several studies, the degree of concern for the 

susceptibility is low because: 

• Doses and endpoints selected for risk assessment are protective of the observed effects. 

• The dietary food exposure assessment is not likely to underestimate exposure/risk. 

Page 18 of 61 
• The dietary drinking water assessment utilizes water concentration values generated by 

models and associated modeling parameters that are designed to provide conservative, 

health protective, high-end estimates of concentrations in water that are not likely to be 

exceeded. 

• The residential exposure assessment was conducted using standard, health-protective 

assumptions. 

3.5 Hazard Identification and Toxicity Endpoint Selection

3.5.1 Acute Reference Dose (aRfD) - Females age 13-49

Study Selected: Developmental Toxicity Study – rabbit (OPPTS 870.3700) 

MRID No.: 45422713, 45422712 

Dose and Endpoint for Establishing aRfD: Developmental NOAEL = 25 mg/kg/day based on an 

increased litter incidence of a missing lobe of the lung observed at the LOAEL of 75 mg/kg/day. 

Uncertainty Factor(s): An UF of 100 was applied to account for inter-species extrapolation (10X) 

and intra-species variation (10X). 

Comments on Study/Endpint/Uncertainty Factors:

The acute dietary endpoint for females in the 13 to 49 year age group is based on an increased 

litter incidence of a missing lobe of the lung. This developmental effect is presumed to occur 

following a single oral dose and is considered an appropriate endpoint for this population 

subgroup (i.e., women who could potentially be pregnant). Other effects observed at 75 

mg/kg/day were premature deliveries, decreased gravid uterine weights and decreased litter 

average for ossified sternal centra per fetus; however, these are not considered to be single-dose 

effects. 

 Acute RfD = 25 mg/kg/day (NOAEL) = 0.25 mg/kg/day 

 100 (UF) 

3.5.2 Acute Reference Dose (aRfD) - General Population

Study Selected: Special neurotoxicity/pharmacology study in mice (Non-guideline) 

MRID No.: 45422823 

Dose and Endpoint for Establishing aRfD: NOAEL = 25 mg/kg/day based on transient signs of 

decreased spontaneous motor activity, tremors and deep respirations observed at the LOAEL of 

50 mg/kg/day. 

Page 19 of 61 
Uncertainty Factor(s): An UF of 100 was applied to account for inter-species extrapolation (10X) 

and intra-species variation (10X). 

Comments on Study/Endpoint/Uncertainty Factors: The acute dietary endpoint for the general 

population is based on transient signs of decreased spontaneous motor activity, tremors and deep 

respirations in the mouse following a single oral dose. This endpoint is considered appropriate 

for the general population (including infants and children) because the effects were observed 

following a single dose and the route of administration (oral) is appropriate for dietary 

considerations. 

 Acute RfD = 25 mg/kg/day (NOAEL) = 0.25 mg/kg/day 

 100 (UF) 

3.5.3 Chronic Reference Dose (cRfD)

Study Selected: 2-Generation Reproduction Toxicity Studies—rat (OPPTS 870.3800) 

MRID No.: 45422714; 45422715 and 45422716 

Dose and Endpoint for Establishing cRfD: NOAEL = 9.8 mg/kg/day based on decreased body 

weight gains and delayed sexual maturation, decreased absolute thymus weights in F1 pups and 

an increase in stillbirths in both generations observed at the LOAEL of 31.2 mg/kg/day. 

Uncertainty Factor(s): An UF of 100 was applied to account for inter-species extrapolation 

(10X) and intra-species variation (10X). 

Comments on Study/Endpoint/Uncertainty Factors: 

The chronic dietary endpoint is based on offspring effects in the two-generation reproduction 

study: decreased body weight gains and delayed sexual maturation, decreased absolute thymus 

weights in F1 pups and an increase in stillbirths in both generations. This endpoint is considered 

applicable for chronic dietary exposure because the route of administration (oral) is appropriate 

for dietary considerations. The study and endpoint were selected because they are protective of 

effects observed in all the other available studies that could be selected for chronic dietary 

exposure assessment. 

 Chronic RfD = 9.8 mg/kg/day (NOAEL) = 0.098 mg/kg/day 

 100 (UF) 

3.5.4 Incidental Oral Exposure (Short- and Intermediate-Term) 

Study Selected: 2-Generation Reproduction Study - rat (OPPTS 870.3800) 

MRID No.: 45422714, 45422715 and 45422716 

Page 20 of 61 
Dose and Endpoint for Risk Assessment: NOAEL = 9.8 mg/kg/day based on decreased body 

weight gains and delayed sexual maturation and decreased absolute thymus weights in F1 pups 

in both generations at the LOAEL of 31.2 mg/kg/day. 

Uncertainty Factor(s): An UF of 100 was applied to account for inter-species extrapolation (10X) 

and intra-species variation (10X). 

Comments on Study/Endpoint: 

This endpoint is based on an oral study, which is the route of interest for an incidental oral risk 

estimate. The study and endpoint were selected because they are protective of effects observed 

in all the other available studies. The endpoint is appropriate for all durations, as the effect may 

be a result of either short- and/or longer-term exposure. In addition, it is appropriate for 

incidental oral exposure because it is based on offspring effects from the reproduction study. 

3.5.5 Dermal Absorption

Dermal Absorption Factor: 1%. 

In a dermal penetration study (MRID 45868001), TI-435 [Clothianidin] as the FS 600 

formulation (10% a.i.) [nitroimino-14C] TI- 435), was administered to five male Rhesus 

monkeys. Test material was applied to a shaved area (4 cmX 6 cm) of the skin on the back of 

each animal. The total dose was contained in 100 ml of test substance and was applied at a dose 

of 6.13 ug/cm2. Animals were exposed for 8 hours, and then the application sites were washed. 

Subjects were monitored for 120 hours. Urine and feces were collected for the exposure and the 

subsequent monitoring periods. 

3.5.6 Dermal Exposure (Short-, Intermediate- and Long-Term)

Study Selected: 2-Generation Reproduction Toxicity Studies - rat (OPPTS 870.3800) 

MRID No.: 45422714, 45422715 and 45422716 

Dose and Endpoint for Risk Assessment: The NOAEL = 9.8 mg/kg/day based on decreased body 

weight gains and delayed sexual maturation, decreased absolute thymus weights in F1 pups and 

an increase in stillbirths in both generations observed at the LOAEL of 31.2 mg/kg/day 

Comments on Study/Endpoint: This endpoint is based on an oral study. No dermal studies are 

available. Therefore, an oral study is selected to estimate risk using a route-to-route 

extrapolation. The study and endpoint were selected because it is protective of effects observed 

in all the available studies. The endpoint is appropriate for all durations as the effect may be a 

result of either short- and/or longer-term exposure. Because an oral study was selected, the 

dermal absorption factor of 1% should be used for dermal risk assessment. 

Page 21 of 61 
3.5.7 Inhalation Exposure (Short-, Intermediate- and Long-Term)

Study Selected: 2-Generation Reproduction Toxicity Study - rat (OPPTS 870.3800) 

MRID No.: 45422714, 45422715 and 45422716 

Dose and Endpoint for Risk Assessment: The NOAEL = 9.82 mg/kg/day based on 

Decreased body weight gains and delayed sexual maturation, decreased absolute thymus weights 

in F1 pups and an increase in stillbirths in both generations observed at the LOAEL of 31.2 

mg/kg/day. 

Uncertainty Factor(s): An UF of 100 was applied to account for inter-species extrapolation (10X) 

and intra-species variation (10X). 

Comments about the Study/Endpoint: This endpoint is based on an oral study. No inhalation 

studies are available. Therefore, an oral study is selected to estimate risk using a route-to-route 

extrapolation. The study and endpoint were selected because they are protective of effects 

observed in all the available studies. The endpoint is appropriate for all durations as the effect 

may be a result of either short- and/or longer-term exposure. Absorption via inhalation is 

assumed to be equivalent to absorption via the oral route, i.e., 100% dermal absorption is 

assumed in risk assessment. 

3.5.8 Level of Concern for Margin of Exposure

Table 3.5.8. Summary of Levels of Concern for Risk Assessment. 

Route Short-Term 

(1 - 30 Days) 

Intermediate-Term 

(1 - 6 Months) 

Long-Term 

(> 6 Months) 

Occupational (Worker) Exposure 

Dermal 100 100 100 

Inhalation 100 100 100 

Residential Exposure 

Dermal 100 100 N/A 

Inhalation 100 100 N/A 

Incidental Oral 100 100 N/A 

3.5.9 Recommendation for Aggregate Exposure Risk Assessments

According to FQPA (1996), when there are potential residual exposures to a pesticide, an 

aggregate risk assessment must consider exposures from 3 major routes: oral, dermal, and 

inhalation. 

For all durations, oral, dermal, and inhalation exposures may be aggregated because of the 

selection of a common endpoint for these routes of exposure. 

3.5.10 Classification of Carcinogenic Potential

In accordance with the EPA’s Final Guidelines for Carcinogen Risk Assessment (March, 2005), 

the clothianidin is classified as “Not Likely to be Carcinogenic to Humans.” 

Page 22 of 61 
A statistical analysis showed that the increase in thyroid c-cell tumors in female rats was not 

significant, especially when carcinomas and adenomas were combined. The increased incidence 

of hepatocellular carcinomas in male rats at the low and high doses are just outside historical 

control incidences for the same testing laboratory (only 2 studies) but are within the historical 

control range for the animal supplier. In addition, there was no dose-response and there is no 

continuum (i.e. no preneoplastic lesions and no adenomas). Based on these factors, it was 

determined that there was no evidence of carcinogenicity in rats. There was no evidence of 

carcinogenicity in mice. 

3.5.11 Summary of Toxicological Doses and Endpoints for Use in Human Risk 

Assessments

Table 3.5.1a. Summary of Toxicological Doses and Endpoints for Clothianidin for Use in Dietary and NonOccupational Human Health Risk Assessments. 

Exposure/ 

Scenario 

Point of 

Departure 

Uncertainty/ 

FQPA Safety 

Factors 

Level of Concern 

for Risk 

Assessment 

Study and Toxicological Effects 

Acute Dietary 

Females age 

13-49 

NOAEL = 

25 mg/kg/day 

UFA = 10X 

UFH = 10X 

SFFQPA =1 

 

aRfD=0.25 

mg/kg/day 

aPAD=0.25 

mg/kg/day 

Rabbit developmental study 

LOAEL = 75 mg/kg/day based on increased 

litter incidence of a missing lobe of the lung 

Acute Dietary 

General population

NOAEL = 

25 mg/kg/day 

UFA = 10X 

UFH = 10X 

SFFQPA = 1 

aRfD = 0.25 

mg/kg/day 

aPAD 0.25 

mg/kg/day 

Special neurotoxicity/pharmacol 

study in mice 

LOAEL = 50 mg/kg/day based on transient 

signs of decreased spontaneous motor 

activity, tremors and deep respirations 

Chronic Dietary 

All populations

including infants 

and children 

NOAEL= 

9.8 mg/kg/day 

UFA = 10X 

UFH = 10X 

SFFQPA =1 

cRfD=0.098 

mg/kg/day 

cPAD=0.098 

mg/kg/day 

2-Generation reproduction study 

LOAEL = 31.2 mg/kg/day based on 

decreased body weight gains and delayed 

sexual maturation, decreased absolute thymus 

weights in F1 pups and increased stillbirths in 

both generations 

Incidental Oral 

(short and 

intermediate term) 

NOAEL= 

9.8 mg/kg/day 

UFA= 10X 

UFH= 10X 

SFFQPA=1 

MOE= 100 

(residential and 

occupational) 

2-Generation reproduction study 

LOAEL= 31.2 mg/kg/day based on 

decreased body weight gains and delayed 

sexual maturation, decreased absolute thymus 

weights in F1 pups 

Dermal (all 

durations) 

Oral study 

NOAEL= 

9.8 mg/kg/day 

(dermal 

absorption = 1%) 

UFA= 10X 

UFH= 10X 

SFFQPA=1 

MOE= 100 

(residential and 

occupational) 

2-Generation reproduction study 

LOAEL = 31.2 mg/kg/day based on 

decreased body weight gains and delayed 

sexual maturation, decreased absolute thymus 

weights in F1 pups and increased stillbirths in 

both generations 

Inhalation (all 

durations) 

Oral study 

NOAEL= 

9.8 mg/kg/day 

(inhalation 

absorption = 

100% of oral 

absorption) 

UFA= 10X 

UFH= 10X 

SFFQPA=1 

MOE= 100 

(residential and 

occupational) 

2-Generation reproduction study 

LOAEL = 31.2 mg/kg/day based on 

decreased body weight gains and delayed 

sexual maturation, decreased absolute thymus 

weights in F1 pups and increased stillbirths in 

both generations 

Cancer (oral, 

dermal, inhalation) 

“Not Likely to be Carcinogenic to Humans” 

Page 23 of 61 
Point of Departure (POD) = A data point or an estimated point that is derived from observed dose-response data and 

used to mark the beginning of extrapolation to determine risk associated with lower environmentally relevant human 

exposures. NOAEL = no observed adverse effect level. LOAEL = lowest observed adverse effect level. UF = 

uncertainty factor. UFA = extrapolation from animal to human (interspecies). UFH = potential variation in 

sensitivity among members of the human population (intraspecies). UFL = use of a LOAEL to extrapolate a 

NOAEL. UFS = use of a short-term study for long-term risk assessment. UFDB = to account for the absence of key 

date (i.e., lack of a critical study). FQPA SF = FQPA Safety Factor. PAD = population adjusted dose (a = acute, c 

= chronic). RfD = reference dose. MOE = margin of exposure. LOC = level of concern. N/A = not applicable. 

Table 3.5.1a. Summary of Toxicological Doses and Endpoints for Clothianidin for Use in Occupational 

Human Health Risk Assessments.

Exposure/ 

Scenario 

Point of 

Departure 

Uncertainty/FQPA 

Safety Factors 

Level of Concern 

for Risk Assessment

Study and Toxicological Effects 

Dermal (all 

durations) 

(Adults) 

Oral study 

NOAEL= 

9.8 mg/kg/day 

(dermal 

absorption = 

1%) 

UFA= 10X 

UFH= 10X 

SFFQPA=1 

MOE= 100 

(residential and 

occupational) 

2-Generation reproduction study 

LOAEL = 31.2 mg/kg/day based on 

decreased body weight gains and 

delayed sexual maturation, decreased 

absolute thymus weights in F1 pups 

and increased stillbirths in both 

generations 

Inhalation (all 

durations) 

Oral study 

NOAEL= 

9.8 mg/kg/day 

(inhalation 

absorption = 

100% of oral 

absorption) 

UFA= 10X 

UFH= 10X 

SFFQPA=1 

MOE= 100 

(residential and 

occupational) 

2-Generation reproduction study 

LOAEL = 31.2 mg/kg/day based on 

decreased body weight gains and 

delayed sexual maturation, decreased 

absolute thymus weights in F1 pups 

and increased stillbirths in both 

generations 

Cancer (oral, 

dermal, 

inhalation) 

“Not Likely to be Carcinogenic to Humans” 

Point of Departure (POD) = A data point or an estimated point that is derived from observed dose-response data and 

used to mark the beginning of extrapolation to determine risk associated with lower environmentally relevant human 

exposures. NOAEL = no observed adverse effect level. LOAEL = lowest observed adverse effect level. UF = 

uncertainty factor. UFA = extrapolation from animal to human (interspecies). UFH = potential variation in 

sensitivity among members of the human population (intraspecies). UFL = use of a LOAEL to extrapolate a 

NOAEL. UFS = use of a short-term study for long-term risk assessment. UFDB = to account for the absence of key 

date (i.e., lack of a critical study). FQPA SF = FQPA Safety Factor. PAD = population adjusted dose (a = acute, c 

= chronic). RfD = reference dose. MOE = margin of exposure. LOC = level of concern. N/A = not applicable. 

3.6 Endocrine disruption 

EPA is required under the FFDCA, as amended by FQPA, to develop a screening program to 

determine whether certain substances (including all pesticide active and other ingredients) may 

have an effect in humans that is similar to an effect produced by a naturally occurring estrogen, 

or other such endocrine effects as the Administrator may designate. Following the 

recommendations of its Endocrine Disruptor Screening and Testing Advisory Committee 

(EDSTAC), EPA determined that there was scientific basis for including, as part of the program, 

the androgen and thyroid hormone systems, in addition to the estrogen hormone system. EPA 

also adopted EDSTAC’s recommendation that the Program include evaluations of potential 

effects in wildlife. For pesticide chemicals, EPA will use FIFRA and, to the extent that effects in 

wildlife may help determine whether a substance may have an effect in humans, FFDCA 

Page 24 of 61 
authority to require the wildlife evaluations. As the science develops and resources allow, 

screening of additional hormone systems may be added to the Endocrine Disruptor Screening 

Program (EDSP). 

When the appropriate screening and/or testing protocols being considered under the Agency’s 

EDSP have been developed, clothianidin may be subjected to additional screening and/or testing 

to better characterize effects related to possible endocrine disruption. 

Although there are possible endocrine effects associated with clothianidin, there are no specific 

studies being requested at this time because the effects have been characterized in an acceptable 

2-generation reproduction study with a clear NOAEL and LOAEL as well as in developmental 

studies, and the chronic reference dose (cRfD) selected for clothianidin risk assessments is 

considered protective of the observed possible endocrine effects. To the extent that new or 

revised tests are developed in connection with the EDSP that can provide more information on 

endocrine effects, EPA will consider whether further testing of clothianidin is appropriate. 

4.0 Public Health and Pesticide Epidemiology Data

No public health or epidemiological data were used for this risk assessment. 

5.0 Dietary Exposure/Risk Characterization 

5.1 Pesticide Metabolism and Environmental Degradation

The metabolism of clothainidin in primary crops, rotational crops, livestock, and rats was 

evaluated by the Metabolism Assessment Review Committee (MARC) in 2003. The 

clothianidin risk assessment team concurs with the findings of the MARC regarding the residues 

of concern for risk assessment and tolerance enforcement (Table 5.1.7). 

5.1.1 Metabolism in Primary Crops

Adequate plant metabolism studies are available reflecting the application of [14C]-clothianidin 

as a seed treatment to corn and sugar beets, as foliar applications to apples, and as soil and foliar 

applications to tomatoes. The metabolic profiles in the tested primary crops were similar, in that 

the highest level residue was the parent, clothianidin, with the exception of mature sugar beet 

tops. The metabolic profile from the study with apple is indicative of the metabolic profile in 

other plants and is believed to proceed as follows: (i) hydrolysis of clothianidin to form TZMU1

; 

 

1

 TZMU = N-(2-Chlorothiazol-5-ylmethyl)-N’-methylurea 

TZNG = N-(2-Chloro-5-thiazolylmethyl)-N’-nitroguanidine 

THMN = Thiazolyl hydroxy methyl nitroguanidine 

TZU = N-(2-Chlorothiazol-5-ylmethyl) urea 

TMG = N-(2-Chloro-5-thiazolylmethyl)-N’-methylguanidine 

MNG = N-Methyl-N’-nitroguanidine 

MG = Methyl guanidine 

NTG = Nitroguanidine 

ATMG-Pyruvate = N’-[(2-chlorothiazol-5-ylmethylamino)(methylamino)methylene]-2-oxopropano hydrazide 

ATG-Acetate = N’-[amino(2-chlorothiazol-5-ylmethylamino)methylene] acetohydrazide 

Page 25 of 61 
(ii) N-demethylation of clothianidin to form TZNG; (iii) hydroxylation of clothianidin to form 

THMN and subsequent glucosylation to form THMN-Glc; (iv) N-demethylation of TZMU to 

form TZU; (v) denitrification of clothianidin to form TMG; (vi) loss of the thiazolyl-methyl 

moiety (C-N bond cleavage) from clothianidin to form MNG and reduction of MNG (vii) 

denitrification of MNG to form MG; and (viii) N-demethylation of MNG to form NTG. See 

D260059 (L. Croteau and Y. Donovan, 25 April 2003) for the chemical structures of the various 

clothianidin metabolites. 

5.1.2 Metabolism in Rotational Crops

Adequate confined and limited field rotational crop studies are available. The metabolism of 

clothianidin in primary and rotational crops is similar. Clothianidin, TZNG, and MNG are the 

ROCs in rotational crops for risk assessment. Clothianidin is the ROC for the tolerance 

expression. 

5.1.3 Metabolism in Livestock 

The nature of clothianidin residues in livestock is adequately understood based on acceptable 

goat and hen metabolism studies. Metabolism in livestock involves numerous demethylation and 

denitrification reactions. The ROCs for risk assessment are parent and the metabolites TZU, 

TZG, TZNG, ATMG-pyruvate (ruminants), and ATG-acetate (poultry). For tolerance 

enforcement, clothianidin is the only ROC. 

5.1.4 Environmental Degradation 

The fate and disposition of clothianidin in the environment suggest that it is persistent and 

mobile, stable to hydrolysis, and has potential to leach to ground water, as well as runoff to 

surface waters. The high persistence of clothianidin (aerobic soil metabolism and terrestrial field 

dissipation half-lives ranging from half a year to several years) may cause accumulation of the 

chemical in soils following repeated uses. 

5.1.5 Comparative Metabolic Profile 

The metabolism of clothianidin is complex, with a few major (> 10% of the total radioactive 

residues) and numerous minor metabolites. The list of terminal residues is fairly consistent 

across plants, goats, hens, and rats, although the designation of major vs. minor metabolites 

varies depending on the test species. 

Table 5.1.5. Overview of clothianidin metabolic profile in plant and animal matrices. 

Residue Rat Hen Goat Corn Sugar 

Beet 

Rotational 

Crops Apple Tomato 

Clothianidin 9 9 9 9 9 9 9 9

ACT** 9

ATG-Ac 9* 

ATG-Pyr 9

ATMG-Pyr 9* 

ATMT 9

CTCA** 9 9

Page 26 of 61 
MG 9 9 9 9 9 9

MNG 9 9 9 9 9 9* 9 9

MTCA** 9

NTG 9 9 9 9 9 9 9

THMN 9 9

THMN-Glc 9

TMG 9 9 9 9 9* (tops) 9 9

TMHG 9

TMT 9

TZG 9 9* 9* 

TZMU 9 9 9 9 9 9

TZNG 9 9* 9* 9 9 9* 9 9

TZU 9 9* 9* 9 9 9 9

UREA 9 9 9

* major metabolites 

** ACT, MTCA, CTCA did not show up in hen and goat because only the nitroimino label 

was used. There are also no acute studies with these metabolites. 

5.1.6 Toxicity Profile of Major Metabolites and Degradates 

Acute toxicity and genotoxicity data are available for ATG-acetate, ATMG-pyruvate, TMG, 

TZMU, TZNG, and MNG. The toxicity of ATG-acetate and ATMG-pyruvate appears to be 

similar to that of clothianidin. Acute toxicity tests using LD50 levels indicate that TMG, TZMU, 

and TZNG may be somewhat more toxic than clothianidin. Structurally, these three metabolites 

are nearly identical to clothianidin, differing only in the loss of a nitro and/or methyl group. The 

points of departure used for risk assessment are well below the LD50 levels observed in the acute 

toxicology studies. Given that and the structural similarity between these metabolites and 

clothianidin, HED is assuming that these compounds are toxicologically equivalent to 

clothianidin with respect to the endpoints being used for risk assessment. 

5.1.7 Pesticide Metabolites and Degradates of Concern 

Table 5.1.7. Summary of Metabolites and Degradates to be included in the Risk Assessment and Tolerance 

Expression.

Matrix Residues included in Risk Assessment Residues included in 

Tolerance Expression 

Primary Crop Leafy and Root/Tuber Vegetables: 

Parent + TMG 

Other crops: Parent 

Plants Parent 

Rotational 

Crop 

Parent, TZNG, MNG Parent 

Livestock Ruminant Parent, TZU, TZG, TZNG, ATMG-Pyr Parent 

Poultry Parent, TZU, TZG, TZNG, ATG-Ac Parent 

Drinking Water Parent Not Applicable 

Based on the available metabolism studies, HED concluded that the nature of the residue has 

been adequately delineated, and that parent only is the residue of concern (ROC) to be used for 

the tolerance expression for primary crops. HED had previously determined that future new uses 

on root crops and/or leafy vegetables will require analysis for residues of TMG along with parent 

Page 27 of 61 
in field trial samples and that TMG should be included as a ROC for risk assessment if 

significant levels of TMG were observed. In the current submission, residues of TMG were 

shown to occur in leafy vegetables at levels approximately 10-fold below those of clothianidin. 

5.1.8 Analytical Methodology 

Adequate LC/MS/MS methods are available for both collecting residue chemistry data and 

enforcing tolerances for clothianidin residues in plant (Bayer Methods 00552 and 109240-1) and 

animal (Bayer Method 00624) commodities. The validated limit of quantitation (LOQ) for 

clothianidin in plant commodities is 0.010 ppm, except for wheat straw (0.020 ppm), and the 

validated LOQs are 0.010 ppm in milk and 0.020 ppm in animal tissues. All three of these 

methods have been reviewed by BEAD’s Analytical Chemistry Laboratory (ACL), approved for 

tolerance enforcement, and forwarded to FDA for inclusion in PAM Volume II. More recently, 

another LC/MS/MS method (Morse Method #Meth-164) was proposed for enforcing tolerances 

and collecting data on residues of clothianidin and TMG in grape and potato commodities. This 

method is similar to Method 00552 and involves extraction of residues with acetonitrile/water, 

cleanup using solid phase extraction (SPE) cartridges, and the separate analysis of clothianidin 

and TMG by LC/MS/MS. The validated LOQ for each analyte is 0.02 ppm in all grape and 

potato matrices, except for potato chips and raisins (with LOQs of 0.04 ppm). The method was 

adequately validated in conjunction with the field trials and processing studies and has 

undergone a successful independent laboratory validation (ILV) trial. 

5.1.9 Drinking Water Residue Profile

The Environmental Fate and Effects Division (EFED) provided Tier I Estimated Drinking Water 

Concentrations (EDWCs) for clothianidin in surface water and in ground water for use in human 

health risk assessments (J. Meléndez, D360266, 4 August 2009). The simulation model FIRST 

was used to calculate the surface water EDWCs, and the SCI-GROW model was used to 

calculate the groundwater EDWC. No clothianidin monitoring data were available. Although 

clothianidin is a major metabolite of thiamethoxam in plants and in animals, it was not found in 

thiamethoxam environmental fate studies. Therefore, exposure to clothianidin in drinking water 

due to thiamethoxam uses is not expected. For the simulation models, the application rate of 0.4 

lbs a.i./A for turfgrass was used. This rate is the highest of all the proposed and existing uses. 

The EDWCs for clothianidin in surface waters are 7.29 ppb for acute risk scenarios and 1.35 ppb 

for chronic risk. Clothianidin EDWCs in groundwater are not expected to exceed 5.88 ppb. 

Typically, HED uses the higher of the surface or groundwater estimates for each duration when 

assessing dietary risk (e.g., 7.29 ppb from surface water for acute exposures and 5.88 ppb from 

groundwater for chronic exposures). 

Table 5.1.9 Summary of Estimated Surface Water and Groundwater Concentrations for Clothianidin.

Scenario Surface Water Conc., ppb a Groundwater Conc., ppb b

Acute 7.29 5.88 

Chronic (non-cancer) 1.35 5.88 

a

 From the Tier I FIRST model. Input parameters are based on use of clothianidin on turf grass. 

b

 From the SCI-GROW model assuming a maximum seasonal use rate of 0.4 lb ai/A, a Koc of 84, and a half-life of 

744 days. 

Page 28 of 61 
5.1.10 Food Residue Profile

Valent has submitted field trial data on celery, lettuce (head and leaf), spinach, cauliflower, 

cabbage, mustard greens, tomatoes, peppers, cucumbers, cantaloupes, squash, pecans, almonds, 

figs, pomegranates, cotton and soybeans supporting the proposed uses of clothianidin (50% 

WDG and 2.13 lb/gal FlC) on leafy vegetables, Brassica vegetables, fruiting vegetables, cucurbit 

vegetables, tree nuts, figs, pomegranates, cotton and soybeans. In addition, IR-4 has submitted 

field trial data on cranberries and peach supporting the proposed uses of clothianidin (50% WDG 

and 2.13 lb/gal FlC) on the low-growing berries, except strawberry, Subgroup (13-07H) and 

peaches. 

The field trial data submitted by Valent supporting repeated foliar applications of the 50% WDG 

or 2.13 lb/gal FlC formulations of clothianidin are adequate, although the maximum single

application rate used in the field trials was higher (1.5X) than the proposed rate, with the 

exceptions of the tree nut, fig and pomegranate field trials. For both the 50% WDG and 2.13 

lb/gal FlC formulations, the maximum proposed single foliar application rate is 0.05-0.067 lb 

ai/A for all crops except tree nuts (0.1 lb ai/A), figs (0.09 lb ai/A) and pomegranates (0.09 lb 

ai/A), and the maximum seasonal application rate is 0.2 lb ai/A for all proposed crops. However, 

in each trial, the WDG or FLC formulation was applied twice at a rate of 0.1 lb ai/A (1.5X 

proposed single rate for most crops) for a total of 0.2 lb ai/A (1X proposed seasonal rate). With 

the exceptions of the field trial data on tree nuts, figs and pomegranates, the residue data from 

Valent’s current field trials are likely to slightly over estimate clothianidin residues. 

For the proposed foliar applications, an adequate number of tests were conducted using the 50% 

WDG or 2.13 lb/gal FlC formulation on the required representative crops in the appropriate 

geographic regions at ~1X the proposed maximum seasonal rate, and the appropriate 

commodities were collected from each test around the proposed PHIs. Samples from all the field 

trials were analyzed using adequate LC/MS/MS methods, and the available storage stability data 

support the sample storage durations and conditions. As the proposed use directions are identical 

for the 50% WDG and 2.13 lb/gal formulations, and the PHIs for the foliar applications are >7 

days, the residue data for the WDG or FlC formulations will also support the use of either the 

FlC or WDG formulations (per pending OECD residue chemistry guidelines) on low-growing 

berries, tree nuts, cotton, and soybean. For foliar applications, HED will generally allow for 

translation of residue data between water-diluted formulations (other than ECs, Mcap, and oildispersion formulations) when the proposed PHI is >7 days and residues are shown to decline at 

longer post-treatment intervals (per draft, pending OECD guidelines). Therefore, HED has no 

objections to the translation of formulation-specific residue data for the proposed uses on 

tuberous and corm vegetables, cotton, berries, soybeans, and tree nuts. However, for the other 

crops HED is requesting that bridging trials be completed and submitted in order to evaluate the 

residue levels resulting from these two formulations for uses with a 7-day PHI. Adequate 

residue data were provided for TMG in/on leafy and Brassica vegetables commodities as 

required. 

In addition to the formulation issue, several other deficiencies were noted in Valent’s field trial 

data. First, with the exceptions of the fig and pomegranate field trials, none of the other field 

trials included the use of any adjuvants in the spray mix, although the proposed labels allow for 

Page 29 of 61 
the use of spray adjuvants. The foliar applications were applied at a slightly exaggerated single 

rate (1.5X). HED has evidence that adjuvants can have a significant impact on residue levels, 

potentially increasing them by 4- to 5-fold relative to residues resulting from the same use 

without adjuvants. Therefore, the 1.5X application rate is not sufficient to address the impact of 

adjuvants on residue levels. HED requests that bridging trials be conducted to show the impact 

of adjuvants on residue levels (three trials per representative crop) and that in the mean time, the 

proposed label be revised to disallow the use of spray adjuvants with clothianidin foliar 

treatments, with the exception of applications to figs, pomegranates, and tree nuts except 

almonds (due to residues in/on almond hulls). 

Second, no residue data were submitted on soybean forage and hay following the proposed foliar 

applications. The label should be revised to prohibit the feeding of soybean forage and hay to 

livestock. 

Third, only limited residue data were provided for the WDG formulation comparing the 

proposed single soil application on vegetable crops with repeated foliar applications. Only 1 or 2 

soil application tests were conducted on each vegetable crop, and none of the soil applications 

were applied at the proposed minimum PHI (7 days). Of the 13 soil application tests, the soil 

application was made at planting in 8 tests, at 21 days prior to harvest in 4 tests, and at 1 month 

prior to harvest in 1 test. Although the soil treatment tests do suggest that clothianidin residues 

at ≥21 days following a single soil application at 0.2 lb ai/A are likely to be less than or equal to 

the residues resulting from repeated foliar applications totaling 0.2 lb ai/A, insufficient data are 

available to make this determination. Based on the submitted soil application data, HED also 

assumes that the desired PHI for soil applications is 21 days, as in the studies, rather than the 

currently specified 7-day PHI. 

Data are insufficient to support the soil application use patterns requested. In order to support 

this use pattern, HED recommends bridging studies be conducted to examine the effects of 

application mode (soil vs. foliar) on residue levels. Given the number of variables involved with 

the requested uses (adjuvant use, formulation effects, and soil vs. foliar application), HED 

further recommends that the design of these trials be discussed with HED prior to their initiation. 

Although no field trial data were submitted by Valent supporting the use of the 5 lb/gal FlC 

formulation as a seed (soybean) or seed-piece treatment (potatoes), no new residue data are 

required as the existing residue data on soybeans and potatoes will support the proposed uses. 

For potatoes, adequate field trial data are available supporting an identical use for the 2.13 lb/gal 

FlC formulation (DP# 303164, W. Drew, 2/1/06); these data will support the same use for the 5 

lb/gal FlC formulation. 

For soybeans, the submitted field trial data reflecting foliar applications at up to 0.2 lb 

ai/A/season will cover the proposed seed treatment use, as the proposed use rate from the seed 

treatment would result in a worst-case field rate of 0.05 lb ai/A. Given the longer harvest 

interval and lower use rate for the seed treatment, and the fact that residues in/on soybean seeds 

were detectable in only one soybean seed sample (0.016 ppm) at 21 days following the foliar 

applications, HED concludes that the proposed seed treatment is unlikely to result in residues 

greater than those resulting from the foliar use. 

Page 30 of 61 
Although additional field trial data are being requested from Valent, the available data support 

tolerances of clothianidin at 3.0 ppm on leafy vegetables, 1.9 ppm on Brassica vegetables, 0.2 

ppm on fruiting vegetables, undelinted cottonseed, and pomegranates, 0.06 ppm on cucurbit 

vegetables, 0.05 ppm on figs, 0.01 ppm on tree nuts and pistachios, 1.5 ppm on almond hulls, 4.5 

ppm on cotton gin byproducts, and 0.02 ppm on soybean seed. (Note: although TMG residue 

data will be used for risk assessment, the tolerance for primary crop uses will continue to include 

only the parent compound for enforcement purposes) 

The submitted residue data for TMG in/on leafy and Brassica vegetables and cotton gin 

byproducts are adequate, and the ratio of clothianidin residues to TMG residues was relatively 

consistent for a given crop, generally showing that residues of clothianidin are 10X higher than 

TMG residues.

The field trial data submitted by IR-4 supporting the use of clothianidin (WDG) on peaches and 

low-growing berries (except strawberry) are also adequate, although the peach field trials used an 

exaggerated single application rate (2X). An adequate number of tests were conducted on 

peaches and cranberries using the WDG formulation in the appropriate geographic regions at 

~1X the proposed maximum seasonal rate. The appropriate commodities were collected from 

each test at the proposed PHIs. Samples from all the field trials were analyzed using an adequate 

LC/MS/MS method, and the analyses are supported by the available storage stability data. 

Although no field trial data were submitted supporting the use of the FlC formulation on berries, 

the available residue data for the WDG formulation will be translated to support the FlC 

formulation as the proposed PHI for the foliar applications is 21 days for these crops. However, 

bridging data are required for use of the FlC product on peaches. 

The available peach and cranberry field trial data support the proposed tolerances of 0.70 ppm 

for peaches and 0.01 ppm for low-growing berries, except strawberry (Subgroup 13-07H). 

However, for purposes of international harmonization, HED is recommending a tolerance level 

of 0.80 ppm for residues of clothianidin in/on peaches. 

5.1.11 International Residue Limits

Except for potatoes and peach/stone fruit there are currently no established or proposed Codex, 

Canadian, or Mexican maximum residue limits (MRLs) for clothianidin on the requested 

crops/crop groups. For potato and peach/stone fruit commodities, HED’s recommended 

tolerances are in accord with established/recommended Canadian MRLs. Therefore, 

harmonization with international MRLs is not an issue with this petition. An International 

Residue Limit Status Sheet follows. 

Page 31 of 61 
INTERNATIONAL RESIDUE LIMIT STATUS

Chemical Name: (E)-N-[(2-

Chloro-5-thiazolyl)methyl]-

N’-methyl-N”-nitroguanidine

Common Name: 

Clothianidin 

X Proposed tolerances 

 Reevaluated tolerance 

 Other 

Date: 2/16/09 

Codex Status (Maximum Residue Limits) U. S. Tolerances

X No Codex proposal step 6 or above 

 No Codex proposal step 6 or above for the crops 

requested 

Petition Numbers: 8F7395, 8E7460, and 9F7530 

DP Numbers: 355896, 360842, and 362499 

Other Identifier: PC Code 044309 

Residue definition (step 8/CXL): NA Reviewer/Branch: M. Doherty/RAB II 

Residue definition: Clothianidin 

Crop (s) MRL (mg/kg) Crop(s) Recommended 

Tolerance (ppm) 

Vegetable, leafy, except 

brassica, Group 4 

3.0 

Vegetable, brassica, leafy, 

Group 5 

1.9 

Vegetable, fruiting, Group 8 0.2 

Vegetable, cucurbits, Group 9 0.06 

Fig 0.05 

Nut, tree nuts, Group 14 0.01 

Pistachio 0.01 

Pomegranate 0.20 

Almond, hulls 1.5 

Cotton, undelinted seed 0.20 

Cotton, gin byproducts 4.5 

Soybean, seed 0.02 

Peach 0.70 

Berry, low-growing, except 

strawberry, Subgroup 13-07H 0.01 

Limits for Canada Limits for Mexico 

9 No Limits 

X No Limits for the crops requested 

X No Limits 

9 No Limits for the crops requested 

Residue definition: Clothianidin Residue definition: NA 

Crop(s) MRL (mg/kg) Crop(s) MRL (mg/kg) 

Field corn grain 0.01 

Popcorn grain 0.01 

Rapeseed (canola) 0.01 

Sweet corn kernel plus cob 

with husk removed 

0.01 

Milk 0.01 

Notes/Special Instructions: Potato commodities were recently given MRLs by Canada, as follows: Tubers (0.3 

ppm), chips (0.6 ppm), and granules/flakes (1.5 ppm). PMRA (Canada) is currently reviewing a petition to 

establish tolerances on stone fruit, which includes peaches. HED’s recommended tolerance of 0.7 ppm is 

harmonized with PMRA’s recommended MRL for stone fruit. 

Page 32 of 61 
5.2 Dietary Exposure and Risk

Acute and chronic aggregate dietary (food and drinking water) exposure and risk assessments 

were conducted (M. Doherty, D364363, 11 August 2009) using the Dietary Exposure Evaluation 

Model DEEM-FCIDTM, Version 2.03 which uses food consumption data from the U.S. 

Department of Agriculture’s Continuing Surveys of Food Intakes by Individuals (CSFII) from 

1994-1996 and 1998. The analyses were performed to support Section 3 registration requests for 

clothianidin and thiamethoxam. 

Both the acute and chronic assessments are based on tolerance-level residues, assume 100% crop 

treated, and include estimates for residues of clothianidin in drinking water. Clothianidin is a 

major metabolite of thiamethoxam, and these analyses include thiamethoxam as a source of 

clothianidin exposure. These assessments address requests for new uses of clothianidin as foliar 

treatments on berries (Subgroup 13-07H), Brassica vegetables (Group 5), cotton, cucurbit 

vegetables (Group 9), figs, fruiting vegetables (Group 8), leafy vegetables (Group 4), peaches, 

pomegranates, soybeans, tuberous and corm vegetables (Subgroup 1C), tree nuts (Group 14); as 

seed treatments on root and tuber vegetables (Group 1), bulb vegetables (Group 3), leafy greens 

(Subgroup 4A), Brassica leafy vegetables (Subgroup 5B), fruiting vegetables (Group 8), cucurbit 

vegetables (Group 9), and cereal grains (except rice; Group 15); and new uses of thiamethoxam 

on rice, sugar beets, and tropical fruits. 

 

Based on highly conservative, health-protective assumptions, the aggregate dietary risk estimates 

are below HED’s level of concern (100% of the population-adjusted dose, PAD) for all durations 

and population subgroups. For the acute assessment, the maximum estimated risk is for 23% of 

the acute PAD (aPAD). Similarly, the maximum estimated risk for the chronic assessment is for 

children 1-2 years of age at 19% of the chronic PAD (cPAD). Clothianidin is not a human 

carcinogen; therefore, cancer risk is not an issue for this chemical. Dietary exposure and risk 

estimates are summarized in Table 5.2, below.

Table 5.2. Summary of Dietary Exposure and Risk Estimates for Clothianidin. 

Acute (95th Pecentile of Exposure) Chronic Population Subgroup Exposure, mg/day Risk, % aPAD Exposure, mg/day Risk, % cPAD 

U.S. Population (total) 0.015348 6 0.004582 5 

All infants (< 1 year) 0.048192 19 0.012680 13 

Children 1-2 yrs 0.057589 23 0.018429 19 

Children 3-5 yrs 0.039621 16 0.012188 12 

Children 6-12 yrs 0.018222 7 0.005801 6 

Youth 13-19 yrs 0.011109 4 0.003194 3 

Adults 20-49 yrs 0.010491 4 0.003229 3 

Adults 50+ yrs 0.010650 4 0.003438 4 

Females 13-49 yrs 0.010991 4 0.003325 3 

The population subgroup(s) with the highest exposure/risk estimates are shown in bold. 

Page 33 of 61 
6.0 Residential (Non-Occupational) Exposure/Risk Characterization

The non-occupational/residential exposure/risk assessment is based on the HED’s previous 

assessment (M. Dow, D296176, 24 February 2004). The results of this assessment are 

summarized as follow: 

There is a registered use for clothianidin on turf and, therefore, residential and recreational postapplication exposures are possible. 

Although residential handler exposure is not expected from the currently registered or proposed 

uses of clothianidin, owing to the absence of products registered or proposed for homeowner use, 

the exposure estimates in Table 6 (below) do include adult exposure from commercial 

application to turfgrass via granular push-type spreader. Therefore, this represents an 

overestimate of total exposure. 

The MOEs for the residential post-application exposures/risks range from 1,300 to 490,000 

(Table 6.0). MOE values greater than 100 are considered adequate to protect adults and children 

from residential non-dietary post-application exposures to clothianidin. The estimated MOE’s 

are based upon conservative assumptions and are >1000; therefore, the estimated risks from 

residential non-dietary post-application exposures do not exceed HED’s level of concern. 

Table 6.0. Summary of Residential Post-Application Exposure and Risk Estimates. 

Activity Exposure (Dose) 

mg a.i./kg bw/day MOE 

Adult dermal application 0.000026 370000 

Adult dermal post-application turf contact 0.00108 9100 

Adult golfer post-application turf contact 0.000075 130000 

Adult combined 0.001181 8300 

Toddler oral hand to mouth from contacting treated turf 0.0059 1700 

Toddler incidental oral ingestion of treated soil 0.00002 490000 

Toddler dermal post-application turf contact 0.00155 6300 

Toddler combined 0.00747 1300 

Spray drift is always a potential source of exposure to residents nearby spraying operations. This 

is particularly the case with aerial application but, to a lesser extent, could also be a potential 

source of exposure from the ground application method employed for clothianidin. The Agency 

has been working with the Spray Drift Task Force, EPA Regional Offices and State Lead 

Agencies for pesticide regulation and other parties to develop the best spray drift management 

practices. The Agency is now requiring interim mitigation measures for aerial applications that 

must be placed on product labels/labeling. The Agency has completed its evaluation of the new 

data base submitted by the Spray Drift Task Force, a membership of U.S. pesticide registrants, 

and is developing a policy on how to appropriately apply the data and the AgDRIFT computer 

model to its risk assessments for pesticides applied by air, orchard airblast and ground hydraulic 

methods. After the policy is in place, the Agency may impose further refinements in spray drift 

management practices to reduce off-target drift and risks associated with aerial as well as other 

application types where appropriate. 

Page 34 of 61 
7.0 Aggregate Risk Assessments and Risk Characterization

7.1 Acute Aggregate Risk

Other than dietary exposure, there are no other sources of exposure that constitute an acute 

exposure scenario; therefore, acute aggregate exposure and risk estimates are equivalent to the 

acute dietary exposure and risk estimates summarized in Table 5.2 and are below HED’s level of 

concern. 

7.2 Short- and Intermediate-Term Aggregate Risk

All of the short- and intermediate-term aggregate MOEs are greater than 100 (Table 7.2) and, 

therefore, represent risks that are below HED’s level of concern. 

Table 7.2. Summary of the Short- and Intermediate-Term Aggregate Exposure and Risk Estimates for 

Clothianidin. 

Population Subgroup Total Residential 

Exposure, mg/kg/day 

Chronic Dietary 

Exposure, 

mg/kg/day 

Aggregate 

Exposure1

, 

mg/kg/day 

MOE2 

U.S. Population (total) 0.001181 0.004582 0.005763 1700 

All infants (< 1 year) 0.00747 0.012680 0.020150 480 

Children 1-2 yrs 0.00747 0.018429 0.025899 380 

Children 3-5 yrs 0.00747 0.012188 0.019658 500 

Children 6-12 yrs 0.001181 0.005801 0.006982 1400 

Youth 13-19 yrs 0.001181 0.003194 0.004375 2200 

Adults 20-49 yrs 0.001181 0.003229 0.004410 2200 

Adults 50+ yrs 0.001181 0.003438 0.004619 2100 

Females 13-49 yrs 0.001181 0.003325 0.004506 2200 

The population subgroup with the highest estimated exposure/risk is bolded. 1 Aggregate Exposure = Residential Exposure + Chronic Dietary Exposure 2 Aggregate MOE = NOAEL (9.8 mg/kg/day) ÷ Aggregate Exposure (mg/kg/day) 

7.3 Long-Term Aggregate Risk

Other than dietary exposure, there are no other sources of exposure that constitute a long-term 

exposure scenario; therefore, long-term aggregate exposure and risk estimates are equivalent to 

the chronic dietary exposure and risk estimates summarized in Table 5.2 and are below HED’s 

level of concern. 

7.4 Cancer Risk

Clothianidin has been classified as “not likely to be carcinogenic to humans.” Therefore, cancer 

risk is not a concern for this chemical. 

8.0 Cumulative Risk Characterization/Assessment

Clothianidin is a member of the neonicotinoid class of pesticides and is a major metabolite of 

another neonicotinoid, thiamethoxam. Structural similarities or common effects do not 

Page 35 of 61 
constitute a common mechanism of toxicity. Evidence is needed to establish that the chemicals 

operate by the same, or essentially the same, sequence of major biochemical events (EPA, 2002). 

Although clothianidin and thiamethoxam bind selectively to insect nicotinic acetylcholine 

receptors (nAChR), the specific binding site(s)/receptor(s) for clothianidin, thiamethoxam and 

the other neonicotinoids are unknown at this time. Additionally, the commonality of the binding 

activity itself is uncertain, as preliminary evidence suggests that clothianidin operates by direct 

competitive inhibition, while thiamethoxam is a non-competitive inhibitor. Furthermore, even if 

future research shows that neonicotinoids share a common binding activity to a specific site on 

insect nAChRs, there is not necessarily a relationship between this pesticidal action and a 

mechanism of toxicity in mammals. Structural variations between the insect and mammalian 

nAChRs produce quantitative differences in the binding affinity of the neonicotinoids towards 

these receptors which, in turn, confers the notably greater selective toxicity of this class towards 

insects, including aphids and leafhoppers, compared to mammals. While the insecticidal action 

of the neonicotinoids is neurotoxic, the most sensitive regulatory endpoint for clothianidin is 

based on unrelated effects in mammals, including changes in body and thymus weights, delays in 

sexual maturation, and still births. Additionally, the most sensitive toxicological effect in 

mammals differs across the neonicotinoids (such as testicular tubular atrophy with 

thiamethoxam, and mineralized particles in thyroid colloid with imidacloprid). Thus, there is 

currently no evidence to indicate that neonicotinoids share common mechanisms of toxicity, and 

EPA is not following a cumulative risk approach based on a common mechanism of toxicity for 

the neonicotinoids. For information regarding EPA’s efforts to determine which chemicals have 

a common mechanism of toxicity, and to evaluate the cumulative effects of such chemicals, see 

the policy statements concerning common mechanism determinations, and procedures for 

cumulating effects from substances found to have a common mechanism, released by OPP on 

EPA’s website at http://www.epa.gov/pesticides/cumulative/. 

Note that because clothianidin is a major metabolite of thiamethoxam, EPA has combined 

exposure to clothianidin resulting both from thiamethoxam use, and from use of clothianidin as 

an active ingredient, and has compared this aggregate exposure estimate to relevant endpoints for 

clothianidin. Labeling for formulations containing either of these compounds specifies that other 

neonicotinoid insecticides are not to be applied during the growing season (i.e., a crop treated 

with clothianidin will not be treated with thiamethoxam). Given that, in combination with the 

assumption of 100% crop treated for both the acute and chronic dietary assessments, obviates the 

need to do a combined assessment for crops with approved uses of both clothianidin and 

thiamethoxam. 

9.0 Occupational Exposure/Risk Pathway

Based on the proposed use patterns, handler and post-application exposures to clothianidin may 

occur. In terms of duration, exposures are expected to be of short- or intermediate-term duration; 

long-term (> 6 months) exposures are not expected to occur. 

9.1 Short- and Intermediate-Term Handler Risk

Handler exposures may occur during foliar and seed-treatment uses. Exposure and risk estimates 

for handlers are based on SOPs developed by HED’s Exposure Science Advisory Council and on 

Page 36 of 61 
Page 37 of 61 

data in the Pesticide Handler’s Exposure Database (PHED). Handler exposure and risk estimates 

are summarized in Table 9.1.1 and 9.1.2, below, for the foliar and seed treatment uses, 

respectively. For a complete description of the handler exposure analysis, see D363340 (S. 

Wang, 17 June 2009). 

There are 12 handler scenarios that are expected to result in the highest exposure for the 

proposed foliar and seed-treatment uses: 

• Mixing/Loading Dry Flowable for Ground-boom Applications (Scenario 1) 

• Mixing/Loading Dry Flowable for Airblast Applications (Scenario 2) 

• Mixing/Loading Dry Flowable for Chemigation (Scenario 3) 

• Mixing/Loading Liquid for Ground-boom Applications (Scenario 4) 

• Mixing/Loading Liquid for Airblast Applications (Scenario 5) 

• Mixing/Loading Liquid for Chemigation (Scenario 6) 

• Applying Sprays with Ground-boom Equipment (Scenario 7) 

• Applying Sprays with Airblast Equipment (Scenario 8) 

• Loading (Open)/Applying Liquid for Seed Treatment (Scenario 9) 

• Sewing Seeds after Seed Treatment (Scenario 10) 

• Bagging Seeds after Seed Treatment (Scenario 11) 

• Multiple Activities Worker for Seed Treatment (Scenario 12) 

All of the resulting occupational handler MOEs are greater than 100, indicating that risks 

associated with the above exposure scenarios are below HED’s level of concern.
Table 9.1. Occupational Handler Risk Estimates for the Requested Foliar Uses of Clothianidin. 

Exposure Scenario (Scenario #) 

Personal Protective Equip.a

Dermal Unit Exposureb

(mg/lb ai) 

Inhalation Unit Exposurec

(ug/lb ai) 

Crop Application 

Rate (lb ai/A) 

Amount Treatedd

(A/day) 

Daily Dermal Dosee

(mg/kg/day) 

Daily Inhalation Dosef

(mg/kg/day) 

CombDaily 

(mg/k

Mixer/Loader 

Dry Flowables for ground-boom (1) 

Baseline 0.066 0.77 Vegetables, 

Cott/Soybn, Cranberry i

0.06 80 

200 80 

4.53 E-5 0.000113 4.53 E-5 

5.28 E-5 0.000132 5.28 E-5 

9.81 E0.0009.81 E

Dry Flowables for airblast (2) Baseline 

0.066 0.77 Tree nuts, 

Figs/Pomgnt Peach i

0.1 40 3.77 E-5 0.000044 0.000

Dry Flowables for chemigation (3) 

Baseline 0.066 0.77 Vegetables, 

Cranberry 

0.2 350 0.00066 0.00077 0.001

Liquid for ground-boom (4) 

Baseline 2.9 1.2 Vegetables, 

Cott/Soybn, Cranberry i

0.06 80 

200 80 

0.001989 0.004971 0.001989 

8.23 E-5 0.000206 8.23 E-5 

0.0020.0050.002

Liquid for airblast (5) 

Baseline 2.9 1.2 Tree nuts, 

Figs/Pomgnt Peach i

0.1 40 0.001657 6.86 E-5 0.001

Liquid for chemigation (6) 

Baseline 2.9 1.2 Vegetables, 

Cranberry 

0.2 350 0.029 0.0012 0.030 

Applicator 

Sprays with ground-boom (7) 

Baseline 0.014 0.74 Vegetables, 

Cott/Soybn, Cranberry i

0.06 80 

200 80 

9.6 E-6 0.000024 9.6 E-6 

5.07 E-5 0.000127 5.07 E-5 

0.0000.0000.000

Sprays with airblast (8) 

Baseline 0.36 4.5 Tree nuts, 

Figs/Pomgnt Peach i

0.1 40 0.000206 0.000257 0.000

a Baseline consists of long-sleeve shirt, long pants, shoes, and socks and no respirator. PPE consists of long-sleeve shirt, long pants, shoes, socks, chemical-res

b Baseline Dermal Unit Exposure represents long pants, long sleeved shirt, no gloves, open mixing/loading, and open cab tractors, as appropriate. c Baseline Inhalation Exposure represents no respiratory protection, open mixing/loading, and open cab tractors, as appropriate. 

d Daily acres treated values are from EPA estimates of acreage that could be treated or volume handled in a single day for each exposure scenario of concern, b

and formulation/packaging type.

e Daily dermal dose (mg/kg/d) = [unit dermal exposure (mg/lb ai) * dermal absorption (0.01) * application rate (lb ai/acre) * daily acres treated / body weight f Daily inhalation dose (mg/kg/d) = (unit exposure (μg/lb ai) * (1mg/1000 μg) conversion * application rate (lb ai/acre) * daily acres treated / body weight (70 k

g Combined daily dose = daily dermal dose + daily inhalation dose. h MOE = NOAEL (9.8 mg/kg/d) / combined daily dose. UF = 100. i Vegetables=brassica veg+cucurbit veg+fruiting veg+leafy veg; Cott=cotton; Soybn=soybean; Pomgnt=pomegranate. 

Page 38 of 61 
Page 39 of 61 

Table 9.2. Occupational Handler Risk Estimates for the Requested Soybean Seed-Treatment Use of Clothianidin.Exposure Scenario (Scenario #) 

Personal Protective Equipment 

Dermal Unit Exposure (mg/lb ai) 

Inhalation Unit Exposure (mg/lb ai) 

Seed Species Application 

Rate (lb ai per lb seed) 

Amount Treateda

(lb seed trt per day) 

Daily Dermal Dose b

(mg/kg/day) 

Daily Inhalation Dosec

(mg/kg/day) 

ComDai

(mg

Loader/Applicator 

Loading/Applying Liquids for Seed Treatment (9) 

Single Layer, Gloves 

0.023 0.00034 Soybean 0.0005 718,000 0.0012 0.0017 0.00

Sewer 

Sewing Seeds after Seed treatment (10) 

Single Layer, No Gloves 

0.0062 0.00023 Soybean 0.0005 718,000 0.00032 0.0012 0.00

Bagger 

Bagging Seeds after Seed treatment (11) 

Single Layer, No Gloves 

0.0091 0.00016 Soybean 0.0005 718,000 0.00047 0.00082 0.00

Multiple Activities Worker 

Multiple Activities for Seed treatment (12) 

Single Layer, Gloves 

0.042 0.0016 Soybean 0.0005 718,000 0.0022 0.0082 0.01

a Daily amounts treated values are based on the information provided by the Registrant through Registration Division. b Daily dermal dose (mg/kg/d) = [unit dermal exposure (mg/lb ai) * dermal absorption (0.01) * application rate (lb ai/lb seed) * daily amounts treated / body w

c Daily inhalation dose (mg/kg/d) = (unit exposure (mg/lb ai) * application. rate (lb ai/lb seed) * daily amounts treated / body weight (70 kg). d Combined daily dose (mg/kg/d) = Daily dermal dose (mg/kg/d) + Daily inhalation dose (mg/kg/d). e MOE = NOAEL (9.8 mg/kg/d) / combined daily dose. UF = 100. 
9.2 Short- and Intermediate-Term Post-Application Risk

Post-application exposures may occur during farming activities in treated fields as well as from 

the handling of treated seeds (secondary seed handling). As with the handler occupational 

exposure and risk estimates, the post-application risk estimates are detailed in the assessment by 

S. Wang (D 363340, 17 June 2009). All post-application MOEs are greater than 100 and reflect 

risk estimates that are below HED’s level of concern. The post-application MOEs are 

summarized in Tables 9.2.1 and 9.2.2. 

Table 9.2.1. Post-Application Risk Estimates Associated with the Requested Foliar Uses of Clothianidin at 

Zero Days after Treatment. 

Crop 

Application 

Rate 

(lb ai/A) Work Activity 

Transfer 

Coefficientsa

(cm2

/hr) 

DFRc

(μg/cm2

) 

Daily Dosed

(mg/kg/day) MOE e

 

irrigation, scouting, 

thinning, weeding 

immature plants 

Cotton, 100 0.135 0.000015 640,000 

Soybean 

0.06 

irrigation, scouting, 

weeding mature 

plants 

1500 0.135 0.00023 42,000 

irrigation, scouting, 

weeding, pruning, 

thinning 

Cranberry 0.06 400 0.135 0.000062 160,000 

harvesting, hand 

pruning, pinching, 

training 

1500 0.135 0.00023 42,000 

irrigation, scouting, 

thinning, weeding 

immature plants 

500 0.135 0.000077 130,000 

irrigation, and 

scouting mature 

plants 

1500 0.135 0.00023 42,000 

Brassica Veg. 

Cucurbit Veg. 

Leafy Veg. 

0.06 

hand harvesting, 

pruning, and thinning 

mature plants 

2500 0.135 0.00038 25,000 

irrigation, scouting, 

thinning, weeding 

immature plants 

500 0.135 0.000077 130,000 

irrigation, and 

scouting mature 

plants 

700 0.135 0.00011 91,000 

Fruiting Veg. 0.06 

hand harvesting, 

pruning, staking, 

tying 

1000 0.135 0.00015 64,000 

propping 100 0.224 0.000026 380,000 

irrigation, scouting, 

weeding 

1000 0.224 0.00026 38,000 

Figs, 

Peach 

0.1 

Harvesting, pruning, 

training, tying 

1500 0.224 0.00038 25,000 

Pomegranate 0.1 propping 100 0.224 0.000026 380,000 

irrigation, scouting, 

hand weeding, 

1500 0.224 0.00038 25,000 

Page 40 of 61 
harvesting, pruning, 

training 

Thinning, tying 3000 0.224 0.00077 13,000 

irrigation, scouting, 

thinning, weeding 

Tree Nuts 0.1 500 0.224 0.00013 76,000 

harvesting/poling, 

pruning, thinning 

2500 0.224 0.00064 15,000 

a Transfer coefficient from Science Advisory Council for Exposure: Policy Memo #003 "Agricultural Transfer Coefficients," 05/07/98. 

b Day after treatment represents approximately 12 hours following application when sprays have dried. 

c DFR = Application Rate (lb ai/acre)X Fraction of active ingredient that remains on the foliage when sprays have dried X 4.54E8 

μg/lbX 24.7E-9 acre/cm2

. 

d Daily dose = DFR (μg/cm2

)X TC (cm2/hr)X conversion factor (1 mg/1,000 μg)X exposure time (8 hrs/day)X dermal absorption (0.01) 

/ body weight (70 kg). 

e MOE = NOAEL (9.8 mg/kg/day) / daily dose (mg/kg/day). 

Table 9.2.2. Risk Estimate for Secondary Seed Handlers of Treated Soybean Seed. 

Mitigation 

Level 

Dermal 

Unit 

Exposure 

(mg/lb ai) 

Inhalation 

Unit 

Exposure 

(mg/lb ai) 

Application 

Rate 

(lb ai per 

lb seed) 

Amount 

Planteda

(lb seed 

pnted/day)

Daily 

Dermal 

Dose b

(mg/kg/day) 

Daily 

Inhalation 

Dosec

(mg/kg/day) 

Combined 

Daily Dosed

(mg/kg/day) 

MOEe

 

Single 

Layer, 

Gloves 

0.25 0.0034 0.0005 12,000 0.00021 0.00029 0.0005 20,000 

a Daily amounts planted values are based on the information provided by the Registrant through Registration Division. 

b Daily dermal dose (mg/kg/d) = [unit dermal exposure (mg/lb ai) * dermal absorption (0.01) * application rate (lb ai/lb seed) * daily 

amounts treated / body weight (70 kg). 

c Daily inhalation dose (mg/kg/d) = (unit exposure (mg/lb ai) * application. rate (lb ai/lb seed) * daily amounts treated / body weight (70 

kg). 

d Combined daily dose (mg/kg/d) = Daily dermal dose (mg/kg/d) + Daily inhalation dose (mg/kg/d). 

e MOE = NOAEL (9.8 mg/kg/d) / combined daily dose. UF = 100. 

10.0 Data Needs and Label Recommendations

10.1 Toxicology

None. 

10.2 Residue Chemistry

 • Label directions for Valent’s 50% WDG and 2.13 lb/gal FlC formulations should be 

amended to include rotational crop restrictions. 

 

 • Label directions for Valent’s 50% WDG and 2.13 lb/gal FlC formulations should be 

revised to remove the soil application for vegetable crops. 

 • Label directions for both the seed treatment and foliar application uses on soybeans 

should be amended to prohibit the grazing or feeding for soybean forage and hay to 

livestock. 

 • Label directions for all crops except fig, pomegranate, soybeans and tree nuts (excluding 

almonds) should be revised to prohibit the use of adjuvants. If the petitioner wants to 

Page 41 of 61 
allow the use of adjuvants, side-by-side trials should be conducted. HED recommends 

that the petitioner consult with the Agency prior to conducting any such trials. 

 • To support the use of clothianidin (WDG or FlC) as a soil application on vegetable crops, 

bridging studies are required on selected vegetable crops to compare residues resulting 

from soil vs. foliar applications. Additional field trials are required on leaf lettuce, 

mustard greens, peppers, and cucumbers (3 tests for each crop). In each test, clothianidin 

(WDG or FlC) should be applied separately to side-by-side plots as either a single soil 

application at 0.2 lb ai/A, or as three foliar applications at 0.067 lb ai/A/application at a 

RTI of 7 days, for a total of 0.2 lb ai/A/season. Samples of each commodity should be 

harvested at 21 DAT for the soil application and at 7 DAT for the foliar applications. 

The foliar applications should also include the use of spray adjuvants in each test. If 

residues resulting from the soil application are greater than those coming from the foliar 

use, a full set of trials reflecting residues from soil applications will be required. 

 • The available field trial data reflect the use of the WDG formulation on leafy vegetables, 

Brassica vegetables, fruiting vegetables, cucurbit vegetables, peaches, low-growing 

berries (except strawberry), tree nuts, cotton, and soybeans; and of the FlC formulation 

on figs and pomegranates. Of these, translation between formulations for the foliar uses 

on cotton, berries, legume vegetables, and tree nuts is appropriate since the PHI for these 

uses is greater than one week. For the other uses, side-by-side trials should be conducted 

to demonstrate equivalency of formulations, with respect to residue levels, if registrations 

for both formulations are desired. Due to these formulation issues and the adjuvant 

issues noted above, HED recommends that the petitioner consult with the Agency prior to 

initiating any side-by-side residue trials. 

 • A revised Section F should be submitted amending the proposed tolerances to reflect the 

recommendations made by HED in Table 10. Additionally, the tolerance expression 

should be revised to read as follows: 

 Tolerances are established for residues of the insecticide clothianidin, including its 

metabolites and degradates, in or on the commodities in the table below as a result of 

the application of clothianidin. Compliance with the tolerance levels specified below 

is to be determined by measuring only clothianidin [(E)-N-[(2-Chloro-5-

thiazolyl)methyl]-N’-methyl-N”-nitroguanidine] in or on the commodity. 

Although additional field trial data are being requested, sufficient data are available to support 

permanent tolerances on the requested commodities. HED recommends establishing permanent 

tolerances for residues of clothianidin as detailed in Table 10. Note that HED is currently 

evaluating other petitions for clothianidin requesting registration of seed-treatment uses. 

10.3 Occupational and Residential Exposure

None. 

Page 42 of 61 
Table 10. Tolerance Summary for Clothianidin 

Commodity Proposed/Existing 

Tolerance (ppm) 

Recommended 

Tolerance (ppm)

Comments; 

Correct Commodity Definition

Leafy vegetables, Crop 

Group 4 

3.5 3.0 Adequate data from the foliar application use 

are available on lettuce (head and leaf), celery 

and spinach. 

Vegetable, leafy, except brassica, Group 4 

Brassica (Cole) vegetables, 

Crop Group 5 

3.0 1.9 Adequate data from the foliar application use 

are available on cabbage, cauliflower and 

mustard greens. 

Vegetable, brassica, leafy, Group 4 

Fruiting vegetables, Crop 

Group 8 

0.25 0.20 Adequate data from the foliar application use 

are available on tomatoes and peppers (Bell 

and non-Bell). 

Vegetable, fruiting, Group 8

Cucurbits vegetables, Crop 

Group 9 

0.05 0.06 Adequate data from the foliar application use 

are available on cucumbers, cantaloupes and 

summer squash. 

Vegetable, cucurbits, Group 9

Crop Sub-Group 13-07H 0.01 0.01 Adequate data are available on cranberries. 

Berry, low-growing, except strawberry, 

Subgroup 13-07H 

Tree nuts, Crop Group 14 0.01 0.01 

Pistachio None 0.01 

Adequate data are available on almonds and 

pecans. Nut, tree, Group 14. 

A separate tolerance is also required for 

Pistachio.

Almond, hulls 1.5 1.5 Adequate data are available on almonds. 

Fig 0.05 0.05 Adequate data are available on figs. 

Pomegranate 0.20 0.20 Adequate data are available on pomegranates. 

Peach 

0.70 0.80 

Adequate data are available on peaches. 0.8 

ppm is being recommended for harmonization 

purposes. 

Cotton, seed 0.25 0.20 

Cotton, gin byproducts 4.5 4.5 

Adequate data are available on cotton. 

Cotton, undelinted seed 

Cotton, gin byproducts 

Cotton, meal 0.25 None 

Cotton, hulls 0.25 None 

Cotton, refined oil 0.01 None 

Adequate cotton seed processing data are 

available. As residues were reduced in meal, 

hulls and oil, separate tolerances are not 

required. 

Soybean, seed 0.03 0.02 Adequate data are available 

Soybean, hulls 0.35 None 

Soybean, meal 0.07 None 

Soybean, oil 0.01 None 

Adequate soybean processing data are 

available indicating that quantifiable residues 

are unlikely to occur in soybean processed 

fractions 

Tomato, paste 0.08 None 

Tomato, puree 0.07 None 

Adequate processing data are available on 

tomato indicating that separate tolerances are 

not required for tomato puree and paste. 

Vegetable, tuberous and 

corm, Subgroup 1C 

0.05 0.3 

Potato 0.05 delete 

Adequate residue data are available on 

potatoes to support a subgroup tolerance on 

tuberous and corm vegetables. 

Page 43 of 61 
Table 10. Tolerance Summary for Clothianidin 

Commodity Proposed/Existing 

Tolerance (ppm) 

Recommended 

Tolerance (ppm)

Comments; 

Correct Commodity Definition

Potato, chips None 0.6 

Potato, granules/flakes None 1.5 

Once the subgroup tolerance is established the 

separate tolerance on potatoes can be deleted. 

The recommended tolerances are harmonized 

with current and/or pending MRLs in Canada, 

and are based on seed piece treatments. That 

use produces the highest residue. 

References:

D260059. Clothianidin- Briefing Memorandum for Meeting of Metabolism Assessment 

Review Committee. Y. Donovan, et al. 25 April 2003 

D296176. Clothianidin - Exposure/Risk Assessment for the Proposed New Uses of 

Clothianidin on Turfgrass, Landscape Ornamentals and Tobacco. M. Dow. 24 

February 2004. 

D303164. Clothianidin. Tolerance Petition Requesting Food Use of the Insecticide Clothianidin 

on Grapes, Potatoes, Sorghum, and Cotton (Section 3 Registration). Summary of 

Analytical Chemistry and Residue Data. W. Drew. 1 February 2006. 

D335355. Clothianidin. Tolerance Petition Requesting the Establishment of Permanent 

Tolerances (Associated with Section 3 Registration) for Food/Feed Use of the 

Insecticide as a Seed Treatment on Sugar Beets. Resolution of Rotational Crop Data 

Deficiency. Summary of Analytical Chemistry and Residue Data. W. Drew. 16 

October 2007. 

D355896. Clothianidin; Petitions for Tolerances and Uses on Berries Subgroup 13-07H, 

Brassica Vegetables, Cotton, Cucurbit Vegetables, Figs, Fruiting Vegetables, Leafy 

Vegetables, Peaches, Pomegranates, Soybeans, Tuberous and Corm Vegetables, and 

Tree Nuts. Summary of Analytical Chemistry and Residue Data. M. Doherty. 30 

July 2009 

D363340. Clothianidin: Occupational and Residential Exposure/Risk Assessment of 

Clothianidin for Section 3 Registration of New Uses on Vegetables, Cotton, 

Soybean, Tree Nuts, Figs, Pomegranate, Cranberry and Peach. S. Wang. 17 June 

2009. 

D364363. Clothianidin Acute and Chronic Aggregate Dietary (Food and Drinking Water) 

Exposure and Risk Assessments. M. Doherty. 11 August 2009. 

Page 44 of 61 
Appendix A: Toxicology Assessment

A1. Toxicology Data Requirements

The requirements (40 CFR 158.340) for food uses for clothianidin are in Table 1. Use of the new guideline numbers 

does not imply that the new (1998) guideline protocols were used. 

Test Technical

Required Satisfied

870.1100 Acute Oral Toxicity....................................................... 

870.1200 Acute Dermal Toxicity .................................................. 

870.1300 Acute Inhalation Toxicity.............................................. 

870.2400 Primary Eye Irritation.................................................... 

870.2500 Primary Dermal Irritation .............................................. 

870.2600 Dermal Sensitization...................................................... 

yes 

yes 

yes 

yes 

yes 

yes 

yes 

yes 

yes 

yes 

yes 

yes 

870.3100 Oral Subchronic (rodent) ............................................... 

870.3150 Oral Subchronic (nonrodent) ......................................... 

870.3200 21-Day Dermal .............................................................. 

870.3250 90-Day Dermal .............................................................. 

870.3465 90-Day Inhalation.......................................................... 

yes 

yes 

yes 

no 

no 

yes 

yes 

yes 

- 

- 

870.3700a Developmental Toxicity (rodent)................................... 

870.3700b Developmental Toxicity (nonrodent)............................. 

870.3800 Reproduction ................................................................. 

yes 

yes 

yes 

yes 

yes 

yes 

870.4100a Chronic Toxicity (rodent) .............................................. 

870.4100b Chronic Toxicity (nonrodent)........................................ 

870.4200a Oncogenicity (rat).......................................................... 

870.4200b Oncogenicity (mouse).................................................... 

870.4300 Chronic/Oncogenicity.................................................... 

yes 

yes 

yes 

yes 

yes 

yes 

yes 

yes 

yes 

yes 

870.5100 Mutagenicity—Gene Mutation - bacterial..................... 

870.5300 Mutagenicity—Gene Mutation - mammalian................ 

870.5xxx Mutagenicity—Structural Chromosomal Aberrations... 

870.5xxx Mutagenicity—Other Genotoxic Effects....................... 

yes 

yes 

yes 

yes 

yes 

yes 

yes 

yes 

870.6100a Acute Delayed Neurotox. (hen) ..................................... 

870.6100b 90-Day Neurotoxicity (hen)........................................... 

870.6200a Acute Neurotox. Screening Battery (rat) ....................... 

870.6200b 90-Day Neuro. Screening Battery (rat).......................... 

870.6300 Develop. Neuro.............................................................. 

no 

no 

yes 

yes 

yes 

- 

- 

yes 

yes 

yes 

870.7485 General Metabolism ...................................................... 

870.7600 Dermal Penetration........................................................ 

870.7800 Immunotoxicity.............................................................. 

yes 

yes 

yes 

yes 

yes 

yes 

Special Studies 

Developmental Immunotoxicity.................................. yes yes 

Page 45 of 61 
A2. Toxicity Profiles

Table A.2.1 Acute Toxicity Profile - Clothianidin Technical, Intermediates, and Metabolites

Test Material Guideline 

No. Study Type MRID(s) Results Toxicity Category

Technical 870.1100 Acute oral - rat 45422621 LD50 > 5000 mg/kg IV 

BN0230M 

Metabolite

870.1100 Acute oral - rat 45422628 LD50 > 2000 mg/kg (♂+♀) III 

BN0335E2 

Metabolite

870.1100 Acute oral - rat 45422623 LD50 > 2000 mg/kg (♂+♀) III 

MAI 

Metabolite 

870.1100 Acute oral - rat 45422629 LD50 = 758 mg/kg (♀) 

Males not more susceptible

III 

Clothianidin-CCMTAdduct Intermediate870.1100 Acute oral - rat 45422630 LD50 > 2000 mg/kg (♂+♀) III 

ClothianidinHexahydropyrimidine 

Intermediate

870.1100 Acute oral - rat 45422631 LD50 > 2000 mg/kg (♂+♀) III 

Clothianidin-Triazan 

Intermediate

870.1100 Acute oral - rat 45422632 LD50 > 2000 mg/kg (♂+♀) III 

TMG Metabolite 870.1100 Acute oral - rat 45422625 LD50 < 550 mg/kg (♂) 

LD50 = 567 mg/kg (♀)

II 

TZMU Metabolite 870.1100 Acute oral - rat 45422624 LD50 = 1424 mg/kg (♂) 

LD50 = 1282 mg/kg (♀)

III 

TZNG Metabolite 870.1100 Acute oral - rat 45422626 LD50 > 1450 mg/kg (♂) 

LD50 = 1481mg/kg (♀)

III 

Technical 870.1100 Acute oral - mouse 45422622 LD50 = 389 mg/kg (♂; 

95% C.I. = 380-475) 

LD50 = 465 mg/kg (♀; 

95% C.I. = 384-561) 

LD50 = 425 mg/kg (♂+♀; 

95% C.I. = 380-475)

II 

Technical 870.1200 Acute dermal - rat 45422634 LD50 > 2000 mg/kg III 

Technical 870.1300 Acute inhalation 45422636 LC50 > 5.538 mg/L (♂+♀) IV 

Technical 870.2400 Acute eye irritation 45422701 Slightly irritating to the eye IV 

Clothianidin-CCMTAdduct Intermediate870.2400 Acute eye irritation 45422814 Not irritating to the eye IV 

Clothianidin-Triazan 

Intermediate

870.2400 Acute eye irritation 45422819 Not irritating to the eye IV 

Technical 870.2500 Acute dermal 

irritation 

45422703 Not irritating to the skin IV 

Clothianidin-CCMTAdduct Intermediate870.2500 Acute dermal 

irritation 

45422813 Not irritating to the skin IV 

Clothianidin-Triazan 

Intermediate

870.2500 Acute dermal 

irritation 

45422820 Not irritating to the skin IV 

Technical 870.2600 Skin sensitization 45422705 Is not a sensitizer under 

conditions of study

N/A 

Clothianidin-CCMTAdduct Intermediate870.2600 Skin sensitization 45422815 Is not a sensitizer under 

conditions of study

N/A 

Clothianidin-Triazan 

Intermediate

870.2600 Skin sensitization 45422821 Is a sensitizer under 

conditions of study

N/A 

Page 46 of 61 
Table A.2.2. Subchronic, Chronic and Other Toxicity Profile for Clothianidin

Guide line Study Title MRID Results 

870.3100 90-Day Oral 

Toxicity - rat 

(diet) 

45422809 

(2000) 

45422708 

(4-week) 

Acceptable/ 

guideline 

ppm=0, 150, 500 & 3000 

mg/kg/day (M/F)=0/0, 9.0/10.9, 

27.9/34.0, 202.0/254.2 

NOAEL = 27.9/34.0 mg/kg/day (M/F) 

LOAEL = 202.0/254.2 mg/kg/day (M/F) 

based on decreased BW and BW gain.

870.3150 13-Week Oral 

Toxicity- dog 

(diet) 

45422810 

2000 

45422808 

2000 

4-week 

45422811 

1998 

palatability 

Acceptable/ 

guideline 

ppm=0, 325, 650, 1500 & 2250 

mg/kg/day 

(M/F)=0/0, 9.2/9.6, 19.3/21.2, 

40.9/42.1, 58.2/61.8 

NOAEL = 19.3/42.1 mg/kg/day (M/F) 

LOAEL = 40.9/61.8 mg/kg/day (M/F) 

based on thinness, decreased body weight, 

body weight gain and anemia (1 M); and on 

decreased white blood cells, albumin, and 

total protein (F). 

870.3200 28-Day Dermal 

Toxicity - rat 

45422707 (2000) 

Acceptable/ 

guideline 

mg/kg/day= 0, 100, 300 & 1000 

NOAEL = 1000 mg/kg/day (HDT) 

LOAEL = Not established 

870.3700a Developmental 

Toxicity- rat 

(gavage) 

45422711 (1998) 

45422710 (1998) 

range-finding 

Acceptable/ 

guideline 

mg/kg/day=0, 10, 40 & 125 

Maternal NOAEL = 10 mg/kg/day 

Maternal LOAEL = 40 mg/kg/day based 

on decreased body weight gain and food 

consumption. 

Developmental NOAEL = 125 mg/kg/day 

(HDT) 

Developmental LOAEL = Not established 

870.3700b Developmental 

Toxicity- rabbit 

(gavage) 

45422713 (1998) 

45422712 (1998) 

range-finding 

Acceptable/ 

guideline 

mg/kg/day=0, 10, 25, 75 & 100 

Maternal NOAEL = 25 mg/kg/day 

Maternal LOAEL = 75 mg/kg/day based 

on increased incidences of clinical signs 

(scant feces and orange urine), mortalities, 

decreased food consumption, early delivery, 

abortion, and decreased body weight gain. 

Developmental NOAEL = 25 mg/kg/day 

Developmental LOAEL = 75 mg/kg/day 

based on premature deliveries, decreased 

gravid uterine weights, an increased litter 

incidence of a missing lobe of the lung, and 

decreased litter average for ossified sternal 

centra per fetus. 

Page 47 of 61 
Table A.2.2. Subchronic, Chronic and Other Toxicity Profile for Clothianidin

Guide line Study Title MRID Results 

870.3800 Reproduction 

(2- Generation)- 

rat (diet) 

45422715 (2000) 

45422714 (2000) 

pilot 

45422716 

(2001) 

supplemental 

45422825 (1999) 

rat feed 

45422826 

(1999) 

rat feed 

Acceptable/ 

guideline 

ppm=0, 150, 500 & 2500 

mg/kg/day 

(M/F)=0/0, 9.8/10.7, 

31.2/34.3,163.4/188.8 

Parental/Systemic NOAEL = 31.2/36.8 

mg/kg/day (M/F) 

Parental/Systemic LOAEL = 163.4/188.8 

mg/kg/day (M/F) based on decreased body 

weight, body weight gain, and absolute and 

relative thymus weights. 

Reproductive NOAEL = 31.2/188.8 

mg/kg/day (M/F) 

Reproductive LOAEL = 163.4/not 

established mg/kg/day (M/F) based on 

decreased sperm motility and increased 

number of sperm with detached heads in 

both generations. 

Offspring NOAEL = 9.8/11.5 mg/kg/day 

(M/F) 

Offspring LOAEL = 31.2/36.8 mg/kg/day 

(M/F) based on decreased body weight gains 

and delayed sexual maturation (M), 

decreased absolute thymus weights in F1 

pups of both sexes, and an increase in 

stillbirths in both generations. 

870.4100 Chronic (1 year) 

- dog (diet) 

45422717 (2000) 

45422718 

Acceptable/ 

guideline 

ppm=0, 325, 650, 1500 & 2000 

mg/kg/day (M/F)=0/0, 4.8/8.5, 

16.6/15.0, 36.3/40.1, 46.4/52.9 

NOAEL = 46.4/40.1 mg/kg/day (M/F) 

LOAEL = not established/52.9 mg/kg/day 

(M/F) based on clinical evidence of anemia 

in females. 

Note: dose-related decreases in ALT 

activity observed in mid- and high-dose 

males and females. 

870.4200 Carcinogenicity, 

18-Month - 

mouse (diet) 

45422721 (2000) 

45422709 

(1997) 

4-week 

45422722 

(2001) 

supplementary 

Acceptable/ 

guideline 

ppm=0,100, 350 or 1250 

mg/kg/day 

(M/F)=0/0, 13.5/17.0, 47.2/65.1, 

171.4/215.9 

In addition: 50/sex - 700 ppm (wk 

1-4), 2000 (5-10), 2500 (11-34), 

2000/1800 (M/F) 35-79 

[254,1/322,3] 

NOAEL = 171.4/65.1 mg/kg/day (M/F) 

LOAEL = 254.1/215.9 mg/kg/day (M/F) 

based on decreased body weight and body 

weight gain; decreased food consumption 

and food efficiency in males at the LOAEL. 

No evidence of carcinogenicity.

Page 48 of 61 
Table A.2.2. Subchronic, Chronic and Other Toxicity Profile for Clothianidin

Guide line Study Title MRID Results 

870.4300 Chronic/ 

Carcinogenicity, 

2-Year-rat (diet) 

45422719 (2000) 

45422720 

(2001) 

supplementary 

Acceptable/ 

guideline 

ppm (M/F)=0, 150, 500, 1500 & 

3000 

mg/kg/day 

(M/F)=0/0, 8.1/9.7, 27.4/32.5, 

82.0/97.8, 156.5/193.4 

NOAEL = 82.0/32.5 mg/kg/day (M/F) 

LOAEL = 156.5/97.8 mg/kg/day (M/F) 

based on decreased body weight and food 

consumption and altered hepatocellular 

eosinophilic focus of the liver in both sexes; 

ovary interstitial gland hyperplasia and 

increased lymphohistiocytic infiltrate in 

females; and slightly increased incidences of 

pelvic mineralization and transitional cell 

hyperplasia in the kidney, mottled livers of 

males. 

No evidence of carcinogenicity.

870.5100 Gene Mutation 

bacterial reverse 

mutation assay 

Parent

45422731 (2000) 

Acceptable/ 

guideline 

Small, but significant increase in frequency 

of histidine revertants in TA 1535 strain 

treated at 1500 and 5000 μg/plate +/- S9; 

still present but weaker in its absence. The 

positive response was only reproducible at 

5000 μg/plate +/-S9. Clothianidin 

considered mutagenic under conditions of 

this test. 

870.5100 Gene Mutation 

bacterial reverse 

mutation assay 

Parent

45422732 

(1990) 

Acceptable/ 

guideline 

No mutagenic activity in bacteria (S. 

typhimurium and E. coli) under conditions 

of this assay. 

870.5100 Gene Mutation 

bacterial reverse 

mutation assay 

Parent

45422733 

(1999) 

Acceptable/ 

guideline 

No mutagenic activity in bacteria (S. 

typhimurium) under conditions of this assay.

870.5100 Gene Mutation 

bacterial reverse 

mutation assay 

Parent

45422734 

(1999) 

Acceptable/ 

non-guideline 

(only TA 1535 assayed) 

Only TA 1535 tested. No mutagenic activity 

in bacteria (S. typhimurium) under condtions 

of this assay. 

870.5100 Gene Mutation 

bacterial reverse 

mutation assay 

BN0335E2 

metabolite

45422724 

(2000) 

Acceptable/ 

guideline 

No mutagenic activity in bacteria (S. 

typhimurium) under conditions of this assay.

870.5100 Gene Mutation 

bacterial reverse 

mutation assay 

TZMU 

metabolite

45422725 

(1999) 

Acceptable/ 

guideline 

No mutagenic activity in bacteria (S. 

typhimurium) under conditions of this assay.

870.5100 Gene Mutation 

bacterial reverse 

mutation assay 

methyl 

guanidine 

intermediate

45422726 

(1999) 

Acceptable/ 

guideline 

No mutagenic activity in bacteria (S. 

typhimurium) under conditions of this assay.

870.5100 Gene Mutation 

bacterial reverse 

mutation assay 

TZNG

45422727 

(1999) 

Acceptable/ 

guideline 

No mutagenic activity in bacteria (S. 

typhimurium) under conditions of this assay.

Page 49 of 61 
Table A.2.2. Subchronic, Chronic and Other Toxicity Profile for Clothianidin

Guide line Study Title MRID Results 

metabolite 

870.5100 Gene Mutation 

bacterial reverse 

mutation assay 

TMG 

metabolite

45422728 

(1999) 

Acceptable/ 

guideline 

No mutagenic activity in bacteria (S. 

typhimurium) under conditions of this assay.

870.5100 Gene Mutation 

bacterial reverse 

mutation assay 

BN0230M 

metabolite

45422729 

(2000) 

Acceptable/ 

guideline 

No mutagenic activity in bacteria (S. 

typhimurium) under conditions of this assay.

870.5100 Gene Mutation 

bacterial reverse 

mutation assay 

MAI 

metabolite

45422730 

(1999) 

Acceptable/ 

guideline 

No mutagenic activity in bacteria (S. 

typhimurium) under conditions of this assay.

870.5100 Gene Mutation 

bacterial 

reverse mutation 

assay 

N=Methylnitro

guanidin 

intermediate

45422812 

(2001) 

Acceptable/ 

guideline 

No mutagenic activity in bacteria (S. 

typhimurium) under conditions of this assay.

870.5100 Gene Mutation 

bacterial reverse 

mutation assay 

TI 435-Triazan 

intermediate

45422822 

(2000) 

Acceptable/ 

guideline 

No mutagenic activity in bacteria (S. 

typhimurium) under conditions of this assay.

870.5100 Gene Mutation 

bacterial reverse 

mutation assay 

TI 435-CCMTAdduct

45422816 

(2000) 

Acceptable/ 

guideline 

No mutagenic activity in bacteria (S. 

typhimurium) under conditions of this assay.

870.5300 Gene Mutation - 

in vitro

mammalian cell 

gene mutation 

test (L5178Y 

TK +/- mouse 

lymphoma cells) 

45422737 (2000) 

Acceptable/ 

guideline 

Increases in mutant frequency with and 

without S9 at dose levels that were 

cytotoxic. The observed response was 

primarily due to small colony formation, 

indicating clastogenic activity. 

870.5300 Gene Mutation - 

in vitro

mammalian cell 

gene mutation 

test (V79-HPRT 

Assay) 

45422738 

(1999) 

Acceptable/ 

guideline 

No increase in mutant frequency under the 

conditions of the study. 

870.5300 Gene Mutation 

– in vitro

mammalian cell 

gene mutation 

test (V79 - 

HPRT Assay) 

46339001 

(2003) 

Acceptable/ 

guideline 

There was no evidence of induced mutant 

colonies over background. 

Page 50 of 61 
Table A.2.2. Subchronic, Chronic and Other Toxicity Profile for Clothianidin

Guide line Study Title MRID Results 

870.5375 Cytogenetics - 

in vitro

mammalian 

chromosome 

aberration test 

(CHL Cells) 

Parent

45422736 

(2000) 

Acceptable/ 

guideline 

Significant increases in frequency of cells 

with structural aberrations. Predominant 

types were chromatid breaks and exchanges. 

There was, however, no clear indication of a 

dose-related response in either the presence 

or absence of S9 activation. 

870.5375 Cytogenetics – 

in vitro

mammalian 

chromosome 

aberration test 

(CHL Cells) 

Parent

46339002 

(2003) 

Acceptable/ 

guideline 

Clothianidin was clastogenic in the absence 

of S9 activation but only at precipitating 

concentrations. Some doubt regarding the 

relevance of this finding since clastogenicity 

was abolished when exogenous metabolic 

activation was incorporated into the test 

system and was confined to precipitating 

concentrations. 

870.5395 Cytogenitics - 

mammalian 

erythrocyte 

micronucleus 

test 

Parent

45422740 

(2000) 

Acceptable/ 

guideline 

Clothianidin is considered to be neither 

clastogenic nor aneugenic under these test 

conditions. 

870.5395 Cytogenetics - 

mammalian 

erythrocyte 

micronucleus 

test 

Parent

46339003 

(2003) 

Acceptable/ 

guideline 

No significant increase in the frequency of 

MPCEs in bone marrow after any harvest in 

the test groups up to an overtly toxic dose 

for this test system. 

870.5550 Other Effects - 

DNA Repair 

Test in B. 

subtilis 

Parent

45722735 

(1990) 

Unacceptable/ 

non-guideline (only single plates 

used) 

No potential for DNA damage under these 

conditions. 

870.5500 Other Effects - 

(UDS) in 

Mammalian 

Cells in Culture 

Parent

45422739 

(1999) 

Acceptable/ 

non-guideline 

(only males used) 

No evidence (or a dose related positive 

response) that UDS was induced. 

870.6200a Acute 

Neurotoxicity 

Screening 

Battery-rat 

(gavage) 

45422801 

 (2000) 

45422802 

(2000) 

to establish NOEL 

Acceptable/ 

guideline 

mg/kg=0,100, 200 & 400 

NOEL=0, 20, 40 & 60 

NOAEL = 60 mg/kg 

LOAEL = 100 mg/kg based on FOB 

findings (decreased arousal, motor activity, 

and locomotor activity). 

870.6200b Subchronic 

Neurotoxicity 

Study-rat (diet) 

45422803 (2000) 

45422825 

(1999) 

supplementary 

Acceptable/ 

guideline 

ppm (M/F)=0, 150, 1000 & 3000 

NOAEL = 60.0/71.0 mg/kg/day (M/F) 

LOAEL = 177.0/200.1 mg/kg/day (M/F) 

based on slightly decreased food 

consumption, body weights, and body 

weight gains. 

No evidence of neurotoxicity. 

Page 51 of 61 
Table A.2.2. Subchronic, Chronic and Other Toxicity Profile for Clothianidin

Guide line Study Title MRID Results 

mg/kg/day 

(M/F)=0/0,9.2/10.6, 60.0/71.0, 

177.0/200.1 

870.6300 Developmental 

Neurotoxicity 

Study-rat 

(diet) 

445422804 

(2000) 

Acceptable/ 

non-guideline 

(upgradable with FOB 

information) 

ppm=0, 150, 500 & 1750 

mg/kg/day 

gestation=0, 12.9, 42.9, 142 

lactation=0, 27.3, 90.0, 299.0 

Maternal NOAEL = 42.9 mg/kg/day 

Maternal LOAEL = 142 mg/kg/day based 

on decreased body weights, body weight 

gains, and food consumption. 

Offspring NOAEL = 12.9 mg/kg/day 

Offspring LOAEL = 42.9 mg/kg/day based 

on decreased body weights, body weight 

gains, motor activity, and acoustic startle 

response in females. 

870.7485 Metabolism 

Study- rat 

45422805 (2000) 

45422806 

 (2000) 

Acceptable/ 

guideline 

single dose=2.5 or 250mg/kg; 

14-day repeated dose =25 

mg/kg/day 

Overall recovery: 95-100%. Readily 

absorbed and excreted within 96 hours 

following a single 2.5 mg/kg bw or repeated 

oral dose of 25 mg/kg bw, but at a dose of 

250 mg/kg, absorption became biphasic and 

was saturated. Following single or multiple 

oral low doses (2.5 and 25mg/kg bw, 

respectively) of clothianidin, urinary 

excretion accounted for 89.2-94.6% of the 

administered radioactivity suggesting that a 

multiple exposure regimen did not affect the 

absorption/excretion processes. Urinary 

excretion unaffected following single 250 

mg/kg dose. Excretion via the feces 

accounted for the remainder of the 

administered radioactivity in all treatment 

groups (3.8-8.6%). Rapid absorption and 

distribution of administered radioactivity to 

all organs and tissues followed by rapid 

excretion with reduction to background 

levels in most tissues and organs within 24 

hours. Somewhat greater rate of absorption 

and elimination in females. Excretory 

patterns did not exhibit gender-related 

variability but reflected the delayed 

absorption in the high-dose group. Neither 

clothianidin nor metabolites appear to 

undergo significant sequestration. 

 The metabolites identified (primarily 

oxidative demethylation products and 

cleavage products of the nitrogen-carbon 

bond between the nitroimino and thiazolyl 

moieties) were consistent with Phase I 

processes. Extraction efficiencies appeared 

to be excellent and most components in all 

of the matrices examined (urine, feces, and 

tissues) were adequately quantified and 

characterized. The available data, based 

upon studies using both the nitroimino- and 

the thiazolyl-2-labeled clothianidin, 

Page 52 of 61 
Table A.2.2. Subchronic, Chronic and Other Toxicity Profile for Clothianidin

Guide line Study Title MRID Results 

affirmed the metabolism pathway proposed 

by the investigators. 

870.7485 Metabolism 

Study – mice 

45422807 

(2000) 

Acceptable/ 

non-guideline 

single gavage dose of 5 mg/kg 

Of the administered radioactivity, 98.7-

99.2% was recovered. Readily absorbed and 

excreted within 168 hours following a single 

oral dose of 5 mg/kg body weight. Urine 

was the major route of excretion, accounting 

for 92.4-93.7% of the administered 

radioactivity. Feces accounted for 5.0-6.8% 

of the administered radioactivity. Within 24 

hours, 89.0-91.7 % of the administered 

radioactivity was excreted in the urine and 

4.9-6.2% was excreted in the feces. 

Residual radioactivity in any given tissue at 

168 hours post-dose was considerably less 

than 1% of the administered dose. 

Therefore, neither clothianidin nor its 

metabolites appeared to exhibit potential for 

bioaccumulation. Excretory patterns did not 

exhibit gender-related variability. 

Both urinary and fecal metabolites were 

identified using TLC and radioautography in 

conjunction with known standards and were 

quantified by TLC/LSC . The major 

metabolites in both urine and feces were the 

parent compound (clothianidin) and TZNG 

[N-(2-chlorothiazol-5-ylmethyl)-N-

nitroguanidine] which resulted from Ndemethylation of clothianidin. Extraction 

efficiencies were excellent and most 

components in the urine and feces were 

adequately quantified and characterized. 

Based on the data from the oral 

administration of [nitroimino-14C]-

clothianidin the metabolism pathway 

proposed by the investigators was 

supported. 

870.7600 Dermal 

Penetration – 

monkey 

45868001 (2003) 

Acceptable/ 

non-guideline 

6.13 μg/cm2

8 hour exposure 

Dermal absorption as the sum of urinary and 

fecal excretion and Cage/Pan/Chair Wash, 

Debris was 0.24 (+ 0.11) as percent of dose. 

Adjustment of the direct absorption 

determination was not necessary because 

recovery from the dermal dose was >90%. 

A value of 1% dermal absorption was 

considered appropriate for use in risk 

assessment. This estimation takes into 

account any variability that would have 

likely occurred with testing several dose 

levels. 

870.7800 Immunotoxicity

–rat (adult) 

(diet) 

46536502 

(2004) 

Acceptable/ 

Immunotoxicity NOAEL = 253 mg/kg/day 

(M&F) 

Page 53 of 61 
Table A.2.2. Subchronic, Chronic and Other Toxicity Profile for Clothianidin

Guide line Study Title MRID Results 

guideline 

ppm=0, 150, 500 & 3000 

mg/kg/day 

(M/F)=0/0, 13.8/14.0, 45.8/46.2, 

252.8/253 

Immunotoxicity LOAEL = not established 

At the highest dose tested, 253 mg/kg/day, a 

decrease in body weights, body weight gains 

and food consumption were noted in adult 

males and females. 

Non-guideline Developmental 

Immunotoxicity 

study - rat 

(diet) 

47526501 (2008) 

Acceptable/ 

non-guideline 

ppm=0, 150, 500 & 2000 

mg/kg/day 

gestation=0, 10, 35, 121 

lactation=0, 22, 68, 250 

after weaning: 

Assay 1=0/0, 28/26, 

98/93,404/404 

Assay 2=0/0, 28/27, 89/93, 

338/398 

No immunotoxicological adverse effects at 

any of the doses tested. 

Non-guideline Other 

Genotoxicity – 

Unscheduled 

DNA synthesis 

in primary rat 

hepatocytes 

46339004 

(2003) 

Acceptable/ 

non-guideline 

No evidence of DNA damage and repair in 

this test system, as determined by 

radioactive tracer procedures (nuclear silver 

grain counts). 

Non-guideline Special Study: 

Neurotoxicity 

and 

pharmacology - 

mouse 

445422823 

(2000) 

Acceptable/ 

non-guideline 

mg/kg=0, 12.5, 25, 50, 100, 200, 

400 (single gavage dose) 

NOAEL = 25 mg/kg/day (M/F) 

LOAEL = 50 mg/kg (M/F) based on 

transient signs of decreased spontaneous 

motor activity, tremors and deep 

respirations. 

Page 54 of 61 
A3. Toxicology Executive Summaries

STUDY TYPE: Developmental Immunotoxicity Study in Rats (diet) - Non-guideline 

PC CODE: 044309 DP BARCODE: D356839 

TXR #: 0054981 SUBMISSION: S835361 

TEST MATERIAL (PURITY): Clothianidin (95.2% a.i.) 

SYNONYMS: TI 435, [C(E)]-N-[(2-chloro-5-thiazolyl)methyl]-N′-methyl-N′′-nitroguanidine 

CITATION: Hoberman, A.M. (2008). Oral (diet) developmental immunotoxicity study of TI 

435 (clothianidin) in Crl: CD(SD) rats. Charles River Laboratories, Preclinical 

Services, Horsham, PA. Laboratory Study no.: 5819-008, August 6, 2008. 

MRID 47526501. Unpublished. 

SPONSOR: Sumitomo Chemical Company, Ltd., 27-1, Shinkawa 2-chome, Chuo-ku, Tokyo, 

Japan 

EXECUTIVE SUMMARY: In a non-guideline developmental immunotoxicity study (MRID 

47526501), 25 presumed pregnant Sprague-Dawley rats/dose group were dosed with 

Clothianidin (95.2% a.i.; batch no. 30037120) in acetone as dietary admixtures at doses of 0, 

150, 500, or 2000 ppm. These doses corresponded, respectively, to doses of 0, 10, 35, or 121 

mg/kg/day for gestation day (GD) 6-20 and 0, 22, 68, or 250 mg/kg/day for lactation day (LD) 0-

13. After weaning (PND 22 to 36), F1-generation rats were offered the dietary formulations at 

the same concentrations as their parents and the corresponded doses were 0, 28/26, 98/93, or 

404/404 mg/kg/day for males/females in Assay 1 and 0, 28/27, 89/93, or 338/398 mg/kg/day for 

males/females in Assay 2, respectively. Prior to PND 21, the F1-generation were potentially 

exposed through the maternal milk and inadvertently to the dam’s dose formulation after 

approximately PND 13. Following weaning, one pup/sex/litter was selected to continue on study 

when possible. Two to three weanlings/sex/dose were evaluated for the following parameters: 

mortality, body weight, body weight gain, food consumption, and gross pathology (sacrificed at 

approximately 7 weeks). The remaining weanlings were assigned to immunoassays. 

Weanlings assigned to Assay 1 (antibody-forming-cell assay) were sensitized by intravenous 

injection of 0.5 ml of sheep erythrocytes (SRBCs) 4 days before sacrifice. Rats were sacrificed at 

41±5 days of age and the thymus and spleen were excised and weighed. The primary IgM antiSRBC antibody-forming-cell responses were determined. Weanlings assigned to Assay 2 

(delayed-type hypersensitivity, DTH) were sensitized by subcutaneous injection of 0.2 ml 

Candida albicans formalin fixed cells in their right flank 8 days before being challenged with 

100 μl injection of Candida albicans chitosan antigen into the foot pad. Swelling of the 

footpads, due to DTH response, was measured with a micrometer prior to challenge and 24 and 

48 hours after the challenge. A challenge-only control group was used to correct for trauma 

associated with the challenge injection. Cycloposphamide (CPS) served as a positive control. 

CPS was administered at a dose of 50 mg/kg (10 mg/mL) in phosphate buffered saline by daily 

Page 55 of 61 
intraperitoneal injection on the last 4 days of exposure for Assay 1 and on the last 4 days before 

challenge for Assay 2. 

For maternal toxicity, no treatment-related effects were observed on mortality or gross pathology 

in the dams. At 2000 ppm in the dams, an increased incidence of ptosis was observed in 6 

animals for a total of 16 observations compared to 0 animals in the other groups. At 2000 ppm, 

the body weights were generally decreased during GD 9-20 by 3-6% and during LD 0-21 by 3-

11%. Body weights gains were decreased during GD 6-9 by 71% and during GD 18-20 by 25%. 

These effects contributed to a decreased body weight gain of 21% for the overall (GD 6-20) 

treatment interval and a decreased body weight gain in the overall (GD 0-20) gestational period 

of 14%. During the lactation period a weight loss was noted during LD 0-3 (-8.0 g) compared to 

controls (4.6 g), and body weight gain remained decreased for LD 3-6 by 58%. Food 

consumption was decreased during the overall treatment, gestational, and lactation periods. 

The maternal LOAEL is 2000 ppm, based on increased incidence of ptosis, and decreased body 

weights and body weight gain, and food consumption. The maternal NOAEL is 500 ppm. 

For offspring toxicity, no treatment-related effects were observed on litter size and litter 

viability. No mortality or clinical signs of toxicity were observed in the offspring after weaning. 

At 2000 ppm, mean pup weights in the treated groups were decreased throughout lactation by 

12-26%. After weaning, decreased body weight and body weight gains were generally observed 

until termination (↓7-29%), and bodyweight gain from PND 22 until termination was decreased 

(p≤0.01) by 24-25% in males and 15-17% in females. Food consumption was decreased for PND 

22-29, 29-36, and 22-36 by 19-34%. 

The offspring LOAEL is 2000 ppm, based on a decreased body weights, body weight gains, and 

food consumption. The offspring NOAEL is 500 ppm. 

For immune function evaluation, there were statistically significant decreases in thymus and 

spleen weight in the F1 weanlings at 2000 ppm for males and females. These decreases might be 

related to significant decreases of body weights at the high dose and was considered secondary 

effect to general systemic toxicity and not direct immunological toxicity. 

The antibody-forming cell assay (humoral immunity) in males showed decreases in total spleen 

cell number, spleen specific activity (AFC/106

 spleen cells) and total spleen activity 

(AFC/spleen) at 2000 ppm while increased activities were observed at 150 and 500 ppm; there 

were no statistical significances with the treated groups compared to controls. In contrast, 

females showed statistically significant increases (p≤0.05) in spleen specific activity (AFC/106

spleen cells, ↑143%) and total spleen activity (AFC/Spleen, ↑99%) at 2000 ppm. However, 

individual animal data showed that the majority of animals in this group showed similar response 

compared with other treated and control groups except 3 females in the 2000 ppm that had higher 

specific activity and total spleen activity than the median response of this group that resulted in 

the statistically significant increased activities of this group compared to the controls. The 

variability of immune response was commonly observed in the outbred SD rats. Therefore, the 

statistical significance may not be biologically significant considering with distribution pattern of 

the responses. The positive control induced the expected response that produced significant 

Page 56 of 61 
decreases in total spleen cell number, specific activity and total spleen activity compared with 

the control. 

For cell-mediated immunity, delayed-type hypersensitivity (DTH) assay did not show treatmentrelated effect at any treated dose at both 24 and 48 hours in this assay for males and females. The 

positive control showed the expected response of significantly suppressive responses at 24 hour 

and 48 hour post-challenge. 

 

Under conditions of this study, there were no immunologically adverse effects on humoral 

or cell-mediated immunity in male and female rats that exposed to clothianidin during the 

prenatal, postnatal and post-weaning period. 

This study is classified acceptable/non-guideline and provides information for use in evaluating 

the potential for immunotoxic effect in offspring rats after exposure to clothianidin during the 

prenatal, postnatal and post-weaning period. 

Page 57 of 61 
STUDY TYPE: Other Genotoxicity: Unscheduled DNA Synthesis in Primary Rat Hepatocytes 

from Treated Rats [No Guideline] 

DPBARCODE: DP309210

PC CODE: 044309 

TEST MATERIAL (PURITY): TI-435 (96.4% a.i/ Batch No.LOT30037120) 

SYNONYMS: Clothianidin 

CITATION: Honarvar, N. (2003). In vivo/in vitro unscheduled DNA synthesis in rat 

hepatocytes with TI-435. RCC – Cytotest Cell Research GmbH, Rossdorf, 

Germany. Laboratory Project ID: 802504, December 9, 2003. MRID 46339004. 

Unpublished. 

SPONSOR: Sumitomo Chemical Takeda Agro Co Ltd., Tokyo, Japan 

EXECUTIVE SUMMARY: In an in vitro/in vivo unscheduled DNA synthesis assay (MRID 

46339004), groups of Wistar male rats (4/group) were administered TI-435 (96.4% a.i/ Batch 

No.LOT30037120) in 0.5% Cremophor at doses of 0, 1000 or 2000 mg/kg. Hepatocytes were 

isolated from 3 animals in each treatment, vehicle or positive [N,N’dimethylhydrazinedihydroxhloride (DMH) and 2-acetylaminofluorene (2-AAF)] control groups at 2 and 16 hours. 

Recovered cells were allowed to attach to coverslips, placed in tridiated thymidine, and prepared 

for autoradiographs. Unscheduled DNA synthesis (UDS) was determined by comparing 

radioactive labeling in hepatocyte nuclei from animals treated with TI-435 to cells recovered 

from the vehicle control group. 

Signs of toxicity similar to those seen in the preliminary study, performed in male and female 

rats with 2000 mg/kg of the test material, were observed in the main assay for both treatment 

groups up to sacrifice. Females were not tested in the main assay because there was no evidence 

of a toxicological difference among the sexes in the preliminary study. There was also no 

evidence of a cytotoxic effect on the harvested hepatocytes. Results for the 2- and 16-hour 

harvests indicated that the test material did not adversely affect DNA since animals did not 

manifest any increases in either the gross nuclear grain counts, (gross nuclear grain counts minus 

cytoplasmic grain counts) at any dose or sacrifice time. By contrast, positive control groups 

showed significant marked increases in the NNGC compared to the vehicle control group. 

Therefore, TI-435 has shown no evidence of DNA damage and repair in this test system, as 

determined by radioactive tracer procedures (nuclear silver grain counts). 

This study is classified as acceptable. As yet, there is no FIFRA Test Guideline for this type of 

in vivo study. 

Page 58 of 61 
STUDY TYPE: In Vivo Mammalian Cytogenetics - Erythrocyte Micronucleus Assay in Mice; 

OPPTS 870.5395 ['84-2]; OECD 474. 

PC CODE: 044309 DP BARCODE: DP309210 

TEST MATERIAL (PURITY): TI-435 (96.4% a.i/ Batch No.LOT30037120) 

SYNONYMS: Clothianidin 

CITATION: Honarvar, N. (2003). TI-435 Micronucleus Assay in Bone Marrow Cells of the 

Mouse. RCC – Cytotest Cell Research GmbH, Rossdorf, Germany. Laboratory 

Project ID: 802503, December 9, 2003. MRID 46339003. Unpublished. 

SPONSOR: Sumitomo Chemical Takeda Agro Co Ltd., Tokyo, Japan 

EXECUTIVE SUMMARY - In a bone marrow micronucleus assay (MRID 46339003), adult 

male and female NMRI mice (5/dose/sex in vehicle, positive or dose group of the test material) 

were treated once via oral gavage with 0, 50, 100 or 200 mg/kg of TI-435 (96.4% a.i./ Batch 

No.LOT30037120) prepared in 0.5% Cremophor. Bone marrow cells were harvested at 24 hours 

for all treatment groups and an additional group administered the high dose was sacrificed at 48 

hours following dosing. Cells were examined for the frequency of micronucleated 

polychromatic erythrocytes (MPCEs) from the count of 2000 PCEs/animal. 

Deaths at 1000 mg/kg and clinical signs of toxicity (reduced spontaneous activity, abdominal 

position, eye closure, and ruffled fur) at ≥100 mg/kg in males and females were noted in the 

preliminary test evaluating a dose range of 100 to 1000 mg/kg in either sex. Accordingly, 200 

mg/kg was selected as the maximum tolerated dose (MTD) for the cytogenetic assay. In general,

similar signs (i.e., reduced spontaneous activity, abdominal position, eye closure, and ruffled fur) 

were noted at 200 mg/kg in males and females for the first 6 hours of treatment and diminished, 

thereafter. There was, however, no evidence of a cytotoxic effect on the bone marrow at any 

dose. The positive control induced the appropriate response. There was no significant increase 

in the frequency of MPCEs in bone marrow after any harvest in the test groups up to an 

overtly toxic dose for this test system.

This study is classified as acceptable/guideline and satisfies the guideline requirement for Test 

Guideline OPPTS 870.5395; OECD 474 for in vivo cytogenetic mutagenicity data. 

Page 59 of 61 
STUDY TYPE: In Vitro Mammalian Cells in Culture Gene Mutation assay in V79 Chinese 

hamster cells; OPPTS 870.5300 [§84-2]; OECD 476. 

PC CODE: 044309 DP BARCODE: D309210 

TEST MATERIAL (PURITY TI-435 (96.4% a.i./Batch No. Lot 300037120) 

SYNONYMS: Chlothianidin 

CITATION: Poth, A.P. (2003). Gene Mutation Assay in Chinese Hamster V79 Cells In Vitro 

(V79/HPRT) with TI-435. RCC-Cytotest Cell Research GmbH, Rossdorf, 

Germany, Study No. 802501. December 9, 2003. MRID 46339001. Unpublished. 

SPONSOR: Sumitomo Chemical Takeda Agro Co. Ltd. Tokyo, Japan 

EXECUTIVE SUMMARY: In a mammalian cell gene mutation assay at the HPRT locus 

(MRID 46339001), V79 Chinese hamster cells cultured in vitro were exposed to TI-435 (96.4% 

a.i., lot 300037120) dissolved in dimethyl sulfoxide (DMSO), at concentrations of 0, 156.3, 

312.5, 625.0, 1250.0 and 2500.0 μg/mL for 4 hours (Experiment 1) in the presence and absence 

of metabolic activation (S9-mix). In addition, V79 cells were continuously exposed to TI-435 

for 24 hours (Experiment 2) at concentrations of 0, 125, 250, 500, 750, 1000 and 1500 μg/mL 

without S9-activation. The S9-mix was obtained from Phenobarbital/β-Naphthoflavone induced 

male Wistar rat liver. 

TI-435 was tested up to the solubility limit (≥1250 μg/mL –S9 and 2500 μg/mL +S9). 

Cytotoxicity as indicated by a strong decrease in relative cloning efficiency (CE) was observed at 

1250 μg/mL (-S9) in Experiment 1 and ≥ 500 μg/mL in Experiment 2, with an mean relative CE 

of ≤ 10%. Little or no cytotoxicity was observed in the presence of S9 mix (relative CE ≥ 90%). 

A slightly greater than 3-fold increase in MF was observed in Exp. 1 at 2500 μg/mL (-S9, trial 1) 

and at 1250 μg/mL (-S9, trial 2) and in Exp. 2 at 1000 μg/mL (-S9, trial 2). However; these 

increases were neither reproducible, nor concentration-related and occurred at concentrations 

that exhibited severe cytotoxicity (relative CE <13%). The MFs per 106

 surviving cells for the 

solvent controls for the two trials (Exp.1) with S9 were 7.7 and 4.0, respectively. No increase in 

MF was observed at any concentration in the presence of S9. The number of mutant colonies per 

106 colonies for solvent and positive controls with and without metabolic activation fell within 

their respective historical control ranges for the testing laboratory.

The positive controls did induce the appropriate responses. There was no evidence of induced 

mutant colonies over background.

This study is classified as Acceptable/Guideline and satisfies the guideline requirement for Test 

Guideline OPPTS 870.5300, OECD 476 for in vitro mutagenicity (mammalian forward gene 

mutation) data. 

Page 60 of 61 
STUDY TYPE: In vitro Mammalian Cytogenetics Assay. 

PC CODE: 044309 DP BARCODE: DP309210 

TEST MATERIAL (PURITY): TI-435 (96.4% a.i/ Batch No.LOT30037120) 

SYNONYMS: Clothianidin 

CITATION: Schultz, M. (2003). In vitro chromosome aberration test in Chinese hamster V79 

Cells with TI-435. RCC – Cytotest Cell Research GmbH, Rossdorf, Germany. 

Laboratory Project ID: 802502, December 9, 2003. MRID 46339002. 

Unpublished. 

SPONSOR: Sumitomo Chemical Takeda Agro Co Ltd., Tokyo, Japan 

EXECUTIVE SUMMARY:

In a mammalian cell cytogenetics assay (chromosome aberration) (MRID 46339002), Chinese 

hamster V79 cultures were exposed to TI-435 (96.4% a.i/ Batch No.LOT30037120) 

prepared in dimethyl sulfoxide (DMSO) at concentrations of 0, 750, 1000, 1500 and 2000 μg/mL 

without metabolic activation for 4 hours and harvested at 18 hours. In the presence of S9 

activation, cells were treated with of 0,500, 750 or 1000 μg/mL for 4 hours and harvested at 18 

hours. The S9 fraction was derived from the livers of male Wistar Han rats induced with 

phenobarbitone/β-naphthoflavone and scored for structural chromosome aberrations. Ethyl 

methane sulfonate (EMS) and cyclophosphamide (CP) served as positive controls in the absence 

and presence of S9, respectively. 

TI-435 was tested up to precipitating concentrations (≥ 1500 μg/mL –S9; ≥ 750μg/mL +S9) but 

was not appreciably cytotoxic (generally ≥ 50% reduction in the mitotic index). Significant 

(p<0.001) and biologically relevant increases were seen at 1500 and 2000 μg/mL – S9 (8.0 and 

24 % aberrant cells, respectively (minus gaps). The most prominent types of aberrations were 

chromatid breaks, fragments and exchanges. The response was abolished in the presence of S9 

activation. No appreciable increase in numerical aberrations was seen at any nonactivated or S9-

activted treatment group. Both positive controls (EMS at 200 μg/mL – S9 and 0.7 μg/mL + S9) 

induced significant (p<0.001) increases in the percentage of cells with aberrations. The solvent 

and positive control values induced the expected responses. It was concluded, therefore, that 

TI-435 was clastogenic in the absence of S9 activation but only at precipitating 

concentrations. There is, however, some doubt regarding the relevance of this finding since 

clastogenicity was abolished when exogenous metabolic activation was incorporated into the test 

system and was confined to precipitating concentrations. 

This study is classified as Acceptable/Guideline and satisfies the guideline requirement for In 

vitro mammalian cytogenetics (chromosome aberrations) OPPTS 870.5375; OECD 473. 

Page 61 of 61