							

	UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

OFFICE OF           

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

October 16, 2007

				

MEMORANDUM

	SUBJECT:	Clothianidin:  Human Health Risk Assessment for Proposed Use
on Sugar Beet.  PC Code:  044309; Petition Number:  6F7159; DP Number: 
D344619.

Regulatory Actions:		Section 3 

		Risk Assessment Type:	Single Chemical/Aggregate

	FROM:	Kelly M. Schumacher, Biologist

		William T. Drew, Chemist

		Suku Oonnithan, Biologist

		Registration Action Branch 2

		Health Effects Division (7509P)

THROUGH: 	Michael A. Doherty, Ph.D., Senior Scientist

		Registration Action Branch 2

		Health Effects Division (7509P)

		And

		Christina Swartz, Branch Chief

		Registration Action Branch 2

		Health Effects Division (7509P)

TO:	Kable Davis, RM 01

Venus Eagle, RM 01

		Insecticide/Rodenticide Branch

		Registration Division (7505P)

	

Table of Contents

  TOC \o "1-3" \h \z \u    HYPERLINK \l "_Toc180308948"  1.0	Executive
Summary	  PAGEREF _Toc180308948 \h  4  

  HYPERLINK \l "_Toc180308949"  2.0	Ingredient Profile	  PAGEREF
_Toc180308949 \h  9  

  HYPERLINK \l "_Toc180308950"  3.0	Hazard Characterization/Assessment	 
PAGEREF _Toc180308950 \h  10  

  HYPERLINK \l "_Toc180308951"  3.1	Hazard and Dose-Response
Characterization	  PAGEREF _Toc180308951 \h  10  

  HYPERLINK \l "_Toc180308952"  3.2	FQPA Considerations	  PAGEREF
_Toc180308952 \h  13  

  HYPERLINK \l "_Toc180308953"  3.3	Hazard Identification and Toxicity
Endpoint Selection	  PAGEREF _Toc180308953 \h  15  

  HYPERLINK \l "_Toc180308954"  3.3.1	Acute Reference Dose (aRfD) -
Females age 13-49	  PAGEREF _Toc180308954 \h  15  

  HYPERLINK \l "_Toc180308955"  3.3.2	Acute Reference Dose (aRfD) -
General Population	  PAGEREF _Toc180308955 \h  15  

  HYPERLINK \l "_Toc180308956"  3.3.3	Chronic Reference Dose (cRfD)	 
PAGEREF _Toc180308956 \h  16  

  HYPERLINK \l "_Toc180308957"  3.3.4	Incidental Oral Exposure (Short-
and Intermediate-Term)	  PAGEREF _Toc180308957 \h  16  

  HYPERLINK \l "_Toc180308958"  3.3.5	Dermal Absorption	  PAGEREF
_Toc180308958 \h  16  

  HYPERLINK \l "_Toc180308959"  3.3.6	Dermal Exposure (Short-,
Intermediate- and Long-Term)	  PAGEREF _Toc180308959 \h  17  

  HYPERLINK \l "_Toc180308960"  3.3.7	Inhalation Exposure (Short-,
Intermediate- and Long-Term)	  PAGEREF _Toc180308960 \h  17  

  HYPERLINK \l "_Toc180308961"  3.3.8	Level of Concern for Margin of
Exposure	  PAGEREF _Toc180308961 \h  18  

  HYPERLINK \l "_Toc180308962"  3.3.9	Recommendation for Aggregate
Exposure Risk Assessments	  PAGEREF _Toc180308962 \h  18  

  HYPERLINK \l "_Toc180308963"  3.3.10	Classification of Carcinogenic
Potential	  PAGEREF _Toc180308963 \h  18  

  HYPERLINK \l "_Toc180308964"  3.3.11	Summary of Toxicological Doses
and Endpoints for Clothianidin for Use in Human Risk Assessments	 
PAGEREF _Toc180308964 \h  18  

  HYPERLINK \l "_Toc180308965"  3.4	Endocrine disruption	  PAGEREF
_Toc180308965 \h  20  

  HYPERLINK \l "_Toc180308966"  4.0	Public Health and Pesticide
Epidemiology Data	  PAGEREF _Toc180308966 \h  20  

  HYPERLINK \l "_Toc180308967"  4.1	Incident Reports	  PAGEREF
_Toc180308967 \h  21  

  HYPERLINK \l "_Toc180308968"  4.2	National Health and Nutritional
Examination Survey (NHANES)	  PAGEREF _Toc180308968 \h  21  

  HYPERLINK \l "_Toc180308969"  4.3	Agricultural Health Study (AHS)	 
PAGEREF _Toc180308969 \h  21  

  HYPERLINK \l "_Toc180308970"  4.4	Other Pesticide Epidemiology
Published Literature	  PAGEREF _Toc180308970 \h  21  

  HYPERLINK \l "_Toc180308971"  5.0	Dietary Exposure/Risk
Characterization	  PAGEREF _Toc180308971 \h  21  

  HYPERLINK \l "_Toc180308972"  5.1	Pesticide Metabolism and
Environmental Degradation	  PAGEREF _Toc180308972 \h  21  

  HYPERLINK \l "_Toc180308973"  5.1.1	Metabolism in Primary Crops	 
PAGEREF _Toc180308973 \h  21  

  HYPERLINK \l "_Toc180308974"  5.1.2	Metabolism in Rotational Crops	 
PAGEREF _Toc180308974 \h  21  

  HYPERLINK \l "_Toc180308975"  5.1.3	Metabolism in Livestock	  PAGEREF
_Toc180308975 \h  22  

  HYPERLINK \l "_Toc180308976"  5.1.4	Analytical Methodology	  PAGEREF
_Toc180308976 \h  22  

  HYPERLINK \l "_Toc180308977"  5.1.5	Environmental Degradation	 
PAGEREF _Toc180308977 \h  22  

  HYPERLINK \l "_Toc180308978"  5.1.6	Pesticide Metabolites and
Degradates of Concern	  PAGEREF _Toc180308978 \h  23  

  HYPERLINK \l "_Toc180308979"  5.1.7	Drinking Water Residue Profile	 
PAGEREF _Toc180308979 \h  23  

  HYPERLINK \l "_Toc180308980"  5.1.8	Food Residue Profile	  PAGEREF
_Toc180308980 \h  24  

  HYPERLINK \l "_Toc180308981"  5.1.9	International Residue Limits	 
PAGEREF _Toc180308981 \h  24  

  HYPERLINK \l "_Toc180308982"  5.2	Dietary Exposure and Risk	  PAGEREF
_Toc180308982 \h  24  

  HYPERLINK \l "_Toc180308983"  5.2.1	Acute Dietary Exposure/Risk	 
PAGEREF _Toc180308983 \h  25  

  HYPERLINK \l "_Toc180308984"  5.2.2	Chronic Dietary Exposure/Risk	 
PAGEREF _Toc180308984 \h  26  

  HYPERLINK \l "_Toc180308985"  5.3	Anticipated Residue and Percent Crop
Treated (%CT) Information	  PAGEREF _Toc180308985 \h  26  

  HYPERLINK \l "_Toc180308986"  6.0	Residential (Non-Occupational)
Exposure/Risk Characterization	  PAGEREF _Toc180308986 \h  26  

  HYPERLINK \l "_Toc180308987"  6.1	Residential Handler Exposure	 
PAGEREF _Toc180308987 \h  27  

  HYPERLINK \l "_Toc180308988"  6.2.	Residential Post-application
Exposure	  PAGEREF _Toc180308988 \h  27  

  HYPERLINK \l "_Toc180308989"  6.3	Other (Spray Drift, etc.)	  PAGEREF
_Toc180308989 \h  28  

  HYPERLINK \l "_Toc180308990"  6.4	Exposure from Use of Tobacco	 
PAGEREF _Toc180308990 \h  28  

  HYPERLINK \l "_Toc180308991"  7.0	Aggregate Risk Assessments and Risk
Characterization	  PAGEREF _Toc180308991 \h  28  

  HYPERLINK \l "_Toc180308992"  7.1	Acute Aggregate Risk	  PAGEREF
_Toc180308992 \h  29  

  HYPERLINK \l "_Toc180308993"  7.2	Short- and Intermediate-Term
Aggregate Risk	  PAGEREF _Toc180308993 \h  29  

  HYPERLINK \l "_Toc180308994"  7.3	Long-Term Aggregate Risk	  PAGEREF
_Toc180308994 \h  29  

  HYPERLINK \l "_Toc180308995"  7.4	Cancer Risk	  PAGEREF _Toc180308995
\h  30  

  HYPERLINK \l "_Toc180308996"  8.0	Cumulative Risk
Characterization/Assessment	  PAGEREF _Toc180308996 \h  30  

  HYPERLINK \l "_Toc180308997"  9.0	Occupational Exposure/Risk Pathway	 
PAGEREF _Toc180308997 \h  31  

  HYPERLINK \l "_Toc180308998"  9.1	Short- and Intermediate-Term Handler
Risk	  PAGEREF _Toc180308998 \h  31  

  HYPERLINK \l "_Toc180308999"  9.2	Short-Term Post-application Risk	 
PAGEREF _Toc180308999 \h  32  

  HYPERLINK \l "_Toc180309000"  10.0	Data Needs and Label
Recommendations	  PAGEREF _Toc180309000 \h  34  

  HYPERLINK \l "_Toc180309001"  10.1	Toxicology	  PAGEREF _Toc180309001
\h  34  

  HYPERLINK \l "_Toc180309002"  10.2	Residue Chemistry	  PAGEREF
_Toc180309002 \h  34  

  HYPERLINK \l "_Toc180309003"  10.3	Occupational and Residential
Exposure	  PAGEREF _Toc180309003 \h  34  

  HYPERLINK \l "_Toc180309004"  References:	  PAGEREF _Toc180309004 \h 
35  

  HYPERLINK \l "_Toc180309005"  A.1	Toxicology Data Requirements	 
PAGEREF _Toc180309005 \h  36  

  HYPERLINK \l "_Toc180309006"  A.2	Toxicity Profiles	  PAGEREF
_Toc180309006 \h  37  

 1.0	Executive Summary  TC \l1 "1.0	Ex

ecutive Summary 

Background

Clothianidin
[(E)-1-(2-chloro-1,3-thiazol-5-ylmethyl)-3-methyl-2-nitroguanidine], a
major metabolite of the active ingredient thiamethoxam, 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.  Clothianidin is currently
registered for use on corn, canola, pome fruit, tobacco, turf,
ornamental plants, grapes, sorghum, potatoes, and cotton.    SEQ CHAPTER
\h \r 1 Permanent tolerances are established for residues of
clothianidin in/on plant and animal commodities (milk only) at 0.01-1.0
ppm.  A time-limited tolerance at 0.02 ppm has been established for
sugar beet roots and tops in conjunction with Section 18 uses in Oregon,
Wyoming, Colorado, and North Dakota.  Tolerances are also established
for the indirect residues of clothianidin at 0.02 ppm in nongrass animal
feeds; forage, fodder, and straw of cereal grains; forage, fodder, and
hay of grasses; and soybean forage and hay.  

Bayer CropScience has requested the establishment of permanent
tolerances in sugar beet roots, tops, and molasses.  The petitioner has
proposed to use Poncho Beta, a multiple-active-ingredient (MAI)
formulation containing 3.33 pounds per gallon (lb/gal) of clothianidin
and 0.44 lb/gal of beta-cyfluthrin, on sugar beet seeds.  This product
is formulated as a suspo-emulsion (SE), which is a combination
formulation consisting of a suspension concentrate coupled with an
oil-based emulsion.  The proposed use is restricted to commercial seed
treatments; applications using equipment for treating seeds at planting
are prohibited.  For clothianidin, the proposed use rate is 0.132 lb
active ingredient (ai) per 100,000 seeds, which is equivalent to
0.068-0.095 lb ai per acre (lb ai/A), based on typical planting rates of
53,000-72,000 seeds per acre.  

Hazard Characterization

Clothianidin does not appear to exhibit toxicity towards a consistent
specific target organ.  Decreases in body weight and body weight gain
were observed in rats, dogs, and mice.  In single-dose studies, mice
(acute toxicity category II) appear more sensitive than rats (category
IV).  Clinical signs of neurotoxicity were exhibited in both mice
(decreased motor activity, tremors, and deep respirations at 50 mg/kg)
and rats (transient signs of decreased arousal, motor activity, and
locomotor activity at 100 mg/kg) in acute neurotoxicity studies
following exposure by gavage; however, no indications of neurotoxicity
were observed following dietary exposure in the subchronic neurotoxicity
study in rats.  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 No
Observed Adverse Effect Levels (NOAELs) were similar for the subchronic
and chronic feeding studies in the rat, a greater spectrum of effects
was observed in the chronic study (decreased body weight, body weight
gain, and food consumption plus additional observations in the liver,
ovary, and kidney) versus the subchronic study (effects only on body
weight and food consumption).  In the rat, administration via the oral
route appears to be more toxic than via the dermal route.  In longer
term studies, dogs 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
gain.  The Hazard Identification Assessment Review Committee (HIARC)
classified clothianidin as not likely to be carcinogenic to humans.  

There was no evidence of increased quantitative or qualitative
susceptibility of rat or rabbit offspring in developmental studies;
however, increased quantitative susceptibility of rat pups was seen in
both the reproduction and developmental neurotoxicity studies.    SEQ
CHAPTER \h \r 1 The degree of concern for both of these studies is low
because the observed effects are well characterized, and there are clear
NOAELs and Lowest Observed Adverse Effect Level (LOAELs).  The NOAEL for
the effects of concern identified in the reproduction study (decreased
mean body weight gain and absolute thymus weights in pups, delayed
sexual maturation, and an increase in still births) is the basis for the
endpoint selected for the chronic dietary and short-, intermediate- and
long-term non-dietary risk assessments.

In adult rats, a guideline immunotoxicity study shows no
clothianidin-mediated immunotoxicity at doses lower than those resulting
in generalized signs of toxicity (e.g., decreases in body weight);
however, it cannot be concluded that a similar lack of effects will
occur in offspring.  Based on evidence of decreased absolute and
adjusted organ weights of the thymus and spleen in multiple studies in
the clothianidin data base and on evidence of increased quantitative
susceptibility of juvenile rats, compared to adults, in the
two-generation reproduction study to these effects, the Health Effects
Division (HED) has recommended that a developmental immunotoxicity (DIT)
study be conducted.  Because results from the DIT could result in a more
protective (i.e., lower) regulatory endpoint, a 10X database uncertainty
factor (UFDB) is applied to both single- and repeated-dose exposure
scenarios (i.e., acute and chronic RfDs, short- and intermediate-term
incidental oral exposures, and short-, intermediate-, and long-term
dermal and inhalation exposures resulting from residential uses of
clothianidin) to account for the lack of this study.

Residue Chemistry

The nature of the residue has been adequately delineated in plants,
based on acceptable corn, sugar beet, apple, and tomato metabolism
studies.  HED has determined that the parent compound is the only
residue of concern (ROC) in primary crops for both tolerance expression
and risk assessment purposes.  The nature of the residue in livestock is
also understood, based on acceptable goat and hen metabolism studies. 
For ruminants, HED concluded that the ROCs for risk assessment include
parent and the metabolites TZU, TZG, TZNG, and ATMG-Pyruvate; for
poultry, HED concluded that the ROCs for risk assessment include parent
and the metabolites TZU, TZG, TZNG, and ATG-Acetate.  However, only
parent needs to be included in the tolerance expression.  

In general, adequate analytical methods, enforcement methods, storage
stability data on parent clothianidin, field trial data, processing
studies, livestock feeding studies, and rotational crop data are
available to support the proposed sugar beet seed treatment use. 
Preliminary storage stability data on TMG support the current sugar beet
field trials and processing studies; however, the final storage
stability study on TMG has not been submitted to the Agency.

Dietary Exposure Assessment

Acute and chronic dietary exposure and risk assessments were conducted
using the Dietary Exposure Evaluation Model (DEEM-FCID™, Version
2.03).  Because clothianidin is a major metabolite of thiamethoxam,
residues of clothianidin resulting from uses of thiamethoxam were
accounted for in these assessments.  The acute assessment is based on
maximum residues of clothianidin observed in clothianidin and
thiamethoxam field trials and assumes 100% crop treated (%CT).  The
chronic assessment is based on average residues from clothianidin and
thiamethoxam field trials and also assumes 100% crop treated.  For crops
that are registered for both thiamethoxam and clothianidin, residue
estimates from each source were added together in order to estimate
dietary exposure.  This method of accounting for thiamethoxam’s
involvement in clothianidin exposure, when coupled with the assumption
of 100% crop treated, likely overestimates that particular contribution
to total exposure, as it results in a potential “double counting” of
clothianidin coming from thiamethoxam for crops that have registered
uses of both compounds.  The empirical processing factor for apple juice
was used for apple and pear juice, and empirical factors were used for
grape juice, raisins, and sugar beet molasses; otherwise, DEEM default
processing factors were used.  The analyses include direct incorporation
of estimated clothianidin residues in drinking water.  For water, the
highest acute estimate from conservative models was used for both the
acute and the chronic dietary exposure analyses.

Based on these highly conservative assumptions, all acute and chronic
dietary risk estimates are below HED’s level of concern (LOC).  

 TC \l2 "5.2  Dietary Exposure and Risk 

Residential Risk

Residential exposures to clothianidin are expected solely from currently
registered uses, with no additional residential exposure expected from
the proposed new use on sugar beet seeds.  Subsequent to the risk
assessment on the residential exposure to clothianidin, thiamethoxam has
been registered for use on turf.  Because the actions of these compounds
are similar and because the thiamethoxam label recommends against the
application of another Group 4A insecticide, it is highly unlikely that
turf would be treated with thiamethoxam and clothianidin simultaneously.
 Since the duration of residential exposure to either compound is
short-term, simultaneous exposure to clothianidin from both sources is
highly unlikely.  Residential exposure to clothianidin applied directly
on turf is expected to be higher than exposure to clothianidin residues
when thiamethoxam is applied on turf, so previously calculated risks for
the use of clothianidin, per se, on turf are considered protective of
residential exposure to clothianidin as either an active ingredient or a
metabolite of thiamethoxam.  

A margin of exposure (MOE) of 1000 or more is sufficient to protect
adults and children from residential exposures to clothianidin.  The
residential risks associated with post-application exposure to
clothianidin residues do not exceed HED’s level of concern for the
general U.S. population or any population subgroup.

Aggregate Risk

The acute aggregate assessment for clothianidin exposure includes only
food and water exposures.  Short- and intermediate-term aggregate
assessments were conducted based on food, water, and residential
exposures.  The long-term aggregate risk assessment includes only food
and water since no long-term exposure scenarios are expected from
residential uses of clothianidin.  Because clothianidin has been
classified as a “not likely human carcinogen,” cancer risk is not a
concern.  Estimates of acute, short-term, intermediate-term, and
long-term aggregate risks associated with the registered and proposed
uses of clothianidin do not exceed HED’s level of concern for the
general U.S. population or any population subgroup.

Occupational Risk

Occupational exposure assessments were conducted for both handler and
post-application exposures for the sugar beet seed treatment use.  The
treatment of sugar beet seeds may last more than a month due to the
longer planting season; therefore, both short- and intermediate-term
occupational exposures were assessed.  A margin of exposure (MOE) of 100
or more is sufficient to protect workers from all of the handler and
post-application occupational exposures to clothianidin.  None of the
risk estimates for any of the occupational scenarios examined in this
assessment exceed HED’s level of concern.

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,"   HYPERLINK
"http://www.eh.doe.gov/oepa/guidance/justice/eo12898.pdf" 
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
Surveys 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.  Whenever
appropriate, nondietary 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 post-application
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.

Review of Human Research

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), have been determined to require a review of their
ethical conduct, and have received that review.  The studies in PHED
were considered appropriate (or ethically conducted) for use in risk
assessments.

Recommendations

Based on the results of our assessment, HED recommends the establishment
of the following permanent tolerances for residues of clothianidin,
pending resolution of the deficiencies noted in Section 10 of this
document:

Beet, sugar, roots	0.02 ppm

Beet, sugar, tops	None

Beet, sugar, molasses	0.05 ppm

Beet, sugar, dried pulp	0.03 ppm

Additional Data Needs

See Section 10.

2.0	Ingredient Profile

Clothianidin is a systemic insecticide that belongs to the
nitroguanidine sub-class of neonicotinoid compounds, which has agonistic
activity on nicotinergic acetylcholine receptors (nAChR).  It is a
metabolite of another neonicotinoid, thiamethoxam.  Clothianidin enters
through the roots and cotyledons of newly germinating seedlings and
protects below- and above-ground plant parts from insect damage.  

The chemical structure and nomenclature of clothianidin are presented in
Table 2.1, and the physicochemical properties of the technical grade of
clothianidin are presented in Table 2.2.

The end-use product for the proposed new use on sugar beet seeds is
Poncho Beta, an MAI formulation containing 3.33 pounds per gallon
(lb/gal) of clothianidin and 0.44 lb/gal of beta-cyfluthrin.  This
product is formulated as a suspo-emulsion (SE), which is a combination
formulation consisting of a suspension concentrate coupled with an
oil-based emulsion.  The proposed use is restricted to commercial seed
treatments; applications are prohibited that use equipment for treating
seeds at planting.  For clothianidin, the proposed use rate is 0.132 lb
active ingredient (ai) per 100,000 seeds, which is equivalent to
0.068-0.095 lb ai per acre (lb ai/A), based on typical planting rates of
53,000-72,000 seeds per acre.  The proposed directions for this new use
of clothianidin are summarized in Table 2.3.



Empirical Formula	C6H8ClN5O2S

Common name	Clothianidin

Company experimental name	TM-444, TI-435, V-10066

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

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

CAS Registry Number	210880-92-5 (formerly 205510-53-8)

End-use product (EP)	Poncho Beta (3.33 lb ai/gal SE; EPA File Symbol
264-RNLA)

Chemical Class	Neonicotinoid (chloronicotinyl)

Known Impurities of Concern	None



Table 2. 2.  Physicochemical Properties of Clothianidin.

Parameter	Value	Reference

Molecular weight	249.7	MRID 45422301

Melting point/range ((C)	176.8

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

	Density (g/cm3) at 20(C	1.61 (PAI), 1.59 (TGAI)

	Water solubility (g/L) at 20°C	0.327

	Solvent solubility (g/L) at 25(C	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 25(C	1.3 x 10-10

	Dissociation constant (pKa) at 20(C	11.09

	Octanol/water partition coefficient (log KOW) at 25(C	0.7

	UV/visible absorption spectrum, maximum (nm)	265.5 (acidic, neutral
solutions)

246.0 (basic solution)

	 

Table 2.3.  Summary of Proposed Directions for New Use of Clothianidin.

Application Timing, Type, and Equipment1	Formulation

[EPA File Symbol]	Application Rate 

(lb ai/100,000 seeds)	Maximum # of Uses per Season	Maximum Seasonal Use
Rate (lb ai/A)2	PHI (days)	Use Directions and Limitations

Sugar beet

Seed treatment; prior to planting; commercial liquid or slurry treaters.
3.33

lb ai/gal SE 3

[264-RNLA]	0.132	1	0.069-0.095	N/A	All seeds treated must be
conspicuously colored at the time of treatment.  Do not use treated seed
for food, feed, or oil processing.

1 To be used only in liquid or slurry seed-treating equipment by
commercial seed treaters.  Do not use in farm      

   equipment for seed treatment at the time of planting.  

2 Maximum field use rate, based on seeding rates of roughly
53,000-72,000 seeds per acre.   

3 This formulation is an SE, which is a heterogeneous preparation
consisting of a stable dispersion of the ai in the

   form of solid particles and fine globules in a continuous water
phase.  It is an MAI which also contains 0.44 lb/gal

   of beta-cyfluthrin.  

3.0	Hazard Characterization/Assessment  TC \l1 "3.0	Hazard
Characterization/Assessment 

3.1	Hazard and Dose-Response Characterization

The toxicology database for clothianidin is complete, with the exception
of a developmental immunotoxicity study.  The scientific quality is
relatively high, and the toxicity profile of clothianidin can be
characterized for most potential developmental, reproductive,
neurotoxic, carcinogenic, and mutagenic effects.  Clothianidin induces
some effects that are similar to other neonicotinoid insecticides,
particularly effects on the liver, hematopoietic system, and kidneys. 

With the exception of the TMG metabolite, most of the metabolites and
intermediates appear to be of similar toxicity to the parent technical
material in acute oral studies.  The TMG metabolite appears to be more
toxic.  In addition, the clothianidin-triazan intermediate tested as a
dermal sensitizer under the conditions of the study, whereas the parent
was not a dermal sensitizer.  

Acute neurotoxicity studies were conducted in both rats and mice
following exposure to clothianidin by gavage.  Comparing these two
studies, mice appear to be more sensitive than rats to the acute
neurotoxic effects of clothianidin.  In the acute neurotoxicity rat
study, FOB effects, including decreased arousal and 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, decreases in body 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 dose
levels 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, decreases in reactivity, grooming, and muscle
tone; prone position; staggering gait; mydriasis; and hypothermia were
observed in mice. 

In rats only, a subchronic neurotoxicity study was conducted following
dietary exposure to clothianidin.  In contrast to the acute
neurotoxicity study described previously, in which neurotoxic effects
were observed after gavage exposure, no indications of neurotoxicity
were noted in the subchronic study following dietary exposure.  Slightly
decreased food consumption, body weights, and body weight gains were the
only observed effects in the subchronic neurotoxicity study. 

 

In subchronic oral studies in rats and dogs, decreases in body weight
and body weight gain were observed in both species.  In addition, dogs
also displayed decreased white blood cells, albumin, and total protein,
as well as some anemia, and they appear to be more sensitive than rats
to the effects of clothianidin following subchronic oral exposure. 
Following subchronic exposures, male dogs are 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, ovary interstitial gland hyperplasia, 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. 

A comparison of the subchronic and chronic feeding studies in the rats
shows 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
of clothianidin to the dog for a longer period of time does not appear
to result in any additional effects or effects at lower dose levels.

In the developmental neurotoxicity study, toxicity in the offspring was
observed at a lower dose level than the dose that caused toxicity in the
maternal animals.  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 the females.  

No quantitative or qualitative susceptibility was observed in either of
the developmental rat or rabbit studies.  In the rat, no developmental
toxicity was observed at the highest dose tested, although this dose
level 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 in which maternal death, a decrease in
food consumption, and clinical signs (scant feces and orange urine) were
observed.  The developmental effects in this 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.

Quantitative susceptibility was observed in the two-generation
reproduction study since the offspring NOAEL is 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 feeding/carcinogenicity study, an apparent increase
in thyroid c-cell tumors was observed in females.  In addition, an
increased incidence of hepatocellular carcinomas in males was examined
more closely.  A statistical analysis revealed that the increase in
thyroid c-cell tumors did not appear to be significant, especially when
carcinomas and adenomas are combined.  The 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.  Finally, there was
no continuum (i.e., no preneoplastic lesions and no adenomas).  There
was no evidence of an increase in tumors in mice.  Therefore,
clothianidin is classified as not likely to be carcinogenic to humans. 
Clothianidin is a major animal and plant metabolite of thiamethoxam. 
Thiamethoxam is not carcinogenic to male and female rats; however,
dietary administration of thiamethoxam is associated with increased
incidence of liver tumors in both sexes of mice.  The fact that
thiamethoxam induces liver tumors in mice and no tumors in rats supports
the argument that clothianidin is not likely to be carcinogenic to
humans because the apparent increases in tumors with clothianidin were
in a different species (rats) and because the tumor of higher potential
concern (thyroid) was not in the same target organ.

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 tested positively, and some tested
negatively.  The HIARC has 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.  Additional data on the composition of the
materials has been submitted and is currently under review.

In some of the toxicological studies, there was evidence of possible
effects on the immune system.  Decreased absolute and adjusted 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.  Even though a guideline
immunotoxicity study showed no clothianidin-mediated immunotoxicity in
adult rats, in the form of a T-cell dependent anti-SRBC-forming cell
response, at doses lower than those resulting in generalized signs of
toxicity (e.g., decreases in body weight), it cannot be concluded that a
similar lack of effects will occur in offspring.  Therefore, the Health
Effects Division (HED) recommends a developmental immunotoxicity (DIT)
study.

In rats, clothianidin was readily absorbed and excreted within 96 hours
following a single low dose 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 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.

 

In mice, clothianidin is 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.

A dermal absorption study with monkeys is available.  In this study,
dermal absorption was calculated at 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 indicate that oral absorption is 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
grossly underestimate anticipated adverse effects.  TC \l2 "3.1	Hazard
and Dose-Response Characterization 

3.2	FQPA Considerations

For a complete history of the FQPA considerations associated with
clothianidin, refer to “Human Health Risk Assessment for Clothianidin.
 Proposal for Tolerance of Residues in/on Pome Fruit and the Use on
Tobacco, Turf, and Ornamental Plants” (D304499, W. Cutchin, 1/6/2005).

On November 14, 2002, the Health Effects Division (HED) Hazard
Identification Assessment Review Committee (HIARC) evaluated the
potential for increased susceptibility of infants and children from
exposure to clothianidin as required by the Food Quality Protection Act
(FQPA) of 1996.  While no quantitative or qualitative susceptibility was
observed in either of the developmental rat or rabbit studies, as
discussed in section 3.1, quantitative susceptibility was observed in
both the developmental neurotoxicity and reproduction rat 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 that caused maternal toxicity. 
However, HIARC 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 lower dose than the dose
that caused parental toxicity.  Based on evidence of decreased absolute
and adjusted organ weights of the thymus and spleen in multiple studies
in the clothianidin data base and on evidence of increased quantitative
susceptibility of juvenile rats, compared to adults, in the
two-generation reproduction study to these effects, the HIARC
recommended that testing be conducted to assess immune system function
in adults and in young animals following exposure during the period of
organogenesis.  Additionally, HIARC determined that there is
insufficient data to justify selection of an additional safety factor
for the protection of infants and children lower than the default value
of 10X and that a UFDB of 10X should be applied to both single and
repeated dose exposure scenarios (i.e., acute and chronic RfDs, short-
and intermediate-term incidental oral exposures, and short-,
intermediate-, and long-term dermal and inhalation exposures resulting
from residential uses of clothianidin) to account for the lack of the
developmental immunotoxicity study (DIT) with clothianidin.  There are
no residual uncertainties for pre- and/or postnatal toxicity for the
two-generation reproduction study because the endpoint of concern is the
one that is being used for short-, intermediate-, and long-term risk
assessments and because an additional safety factor is applied for the
lack of a DIT.  

A guideline immunotoxicity study conducted in adult rats has now been
reviewed by HED and shows no clothianidin-mediated immunotoxicity, in
the form of a T-cell dependent anti-SRBC-forming cell response, in
adults at doses lower than those resulting in generalized signs of
toxicity (e.g., decreases in body weight).  While the antibody response
was intact in adult rats in the presence of decreased lymphoid organ
weights in this study, it cannot be concluded that offspring will
respond similarly.  A DIT study is required to evaluate the immune
response of the offspring.  Because results from the DIT could result in
a more protective (i.e., lower) regulatory endpoint, the 10X UFDB is
applied to account for the lack of this study (D318520, K. Schumacher,
10/17/2006).

In addition to the hazard data, the clothianidin risk assessment team
evaluated the quality of the exposure data and found no residual
uncertainties.  The acute dietary exposure assessment is based on
maximum residues of clothianidin observed in clothianidin and
thiamethoxam field trials and assumes 100% crop treated (%CT).  The
chronic assessment is based on average residues from clothianidin and
thiamethoxam field trials and also assumes 100% crop treated.  For
water, the highest acute estimate from conservative models was used for
both the acute and the chronic dietary exposure analyses.  By using
these conservative assessments, acute and chronic exposures/risks will
not be underestimated.  The residential exposure assessment utilizes
residential SOPs to assess post-application exposure to children as well
as incidental oral ingestion by toddlers.  The residential SOPs are
based on reasonable worst-case assumptions and will not likely
underestimate exposure/risk.  These assessments are unlikely to
underestimate the potential exposure to infants and children resulting
from the use of clothianidin.  Based on these data, the clothianidin
risk assessment team concluded that no additional safety factor is
needed to account for exposure considerations.

3.3	Hazard Identification and Toxicity Endpoint Selection

For a complete discussion of the endpoints, refer to “Human Health
Risk Assessment for Clothianidin.  Proposal for Tolerance of Residues
in/on Pome Fruit and the Use on Tobacco, Turf, and Ornamental Plants”
(D304499, W. Cutchin, 1/6/2005).

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

Study Selected:  Developmental toxicity study in rabbits

MRID Number:  45422713

Dose and Endpoint for Establishing aRfD:  25 mg/kg/day (NOAEL), based on
an increased litter incidence of a missing lobe of the lung observed at
75 mg/kg/day (LOAEL)

Uncertainty Factor(s):  1000X (10X for interspecies variability, 10X for
intraspecies variability, 10X for database uncertainty)

Comments about Study/Endpoint/Uncertainty Factor:  

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.  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.

3.3.2	Acute Reference Dose (aRfD) - General Population

Study Selected:  Special neurotoxicity/pharmacology study in mice and
rats

MRID Number:  45422823

Dose and Endpoint for Establishing aRfD:  25 mg/kg (NOAEL), based on
transient signs of decreased spontaneous motor activity, tremors, and
deep respirations observed at 50 mg/kg (LOAEL)

Uncertainty Factor(s):  1000X (10X for interspecies variability, 10X for
intraspecies variability, 10X for database uncertainty)

Comments about Study/Endpoint/Uncertainty Factor:  

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 because
the effects were observed following a single dose and the route of
administration (oral) is appropriate for dietary considerations.  TC \l3
"3.5.2	Acute Reference Dose (aRfD) - General Population 

3.3.3	Chronic Reference Dose (cRfD) 

Study Selected:  Two-generation reproduction study in the rat

MRID Number:  45422714 through -16 

Dose and Endpoint for Establishing cRfD:  9.8 mg/kg (NOAEL), 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 31.2 mg/kg (LOAEL)

Uncertainty Factor(s):  1000X (10X for interspecies variability, 10X for
intraspecies variability, 10X for database uncertainty)

Comments about Study/Endpoint/Uncertainty Factor:  

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 appropriate 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.

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

Study Selected:  Two-generation reproduction study in the rat 

MRID Number:  45422714 through -16 

Dose and Endpoint for Risk Assessment:  9.8 mg/kg (NOAEL), 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 31.2 mg/kg (LOAEL)

Uncertainty Factor(s):  1000X (10X for interspecies variability, 10X for
intraspecies variability, 10X for database uncertainty)

Comments about Study/Endpoint/Uncertainty Factor:  

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. 
TC \l3 "3.5.4	Incidental Oral Exposure (Short- and Intermediate-Term) 

3.3.5	Dermal Absorption

Dermal Absorption Factor:  1%

A dermal absorption study with monkeys is available.  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 cm x 6 cm) of 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 period and the subsequent monitoring period.  TC \l3
"3.5.5	Dermal Absorption 

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

Study Selected:  Two-generation reproduction study in the rat

MRID Number:  45422714 through -16 

Dose and Endpoint for Risk Assessment:  9.8 mg/kg (NOAEL), 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 31.2 mg/kg (LOAEL)

Uncertainty Factor(s):  1000X (10X for interspecies variability, 10X for
intraspecies variability, 10X for database uncertainty)

Comments about Study/Endpoint/Uncertainty Factor:  

This endpoint is based on an oral study. A dermal study is available;
however, the selected endpoint addresses potential effects on offspring,
which are not examined in the dermal study. Therefore, the study and
endpoint were selected because they are protective of effects observed
in all the available studies. The mouse single-dose and rat single- and
multiple-dose metabolism studies indicate that oral absorption is in the
range of 90% or greater. Therefore, extrapolation from the oral to the
dermal route is not likely to grossly underestimate anticipated adverse
effects. The endpoint is appropriate for all durations as the effect may
be a result of either short- and/or longer-term exposure. A 1% dermal
absorption factor should be used for route-to-route extrapolation.

  TC \l3 "3.5.6	Dermal Exposure (Short-, Intermediate- and Long-Term) 

3.3.7	Inhalation Exposure (Short-, Intermediate- and Long-Term) 

Study Selected:  Two-generation reproduction study in the rat

MRID Number:  45422714 through -16 

Dose and Endpoint for Risk Assessment:  9.8 mg/kg (NOAEL), 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 31.2 mg/kg (LOAEL)

Uncertainty Factor(s):  1000X (10X for interspecies variability, 10X for
intraspecies variability, 10X for database uncertainty)

Comments about Study/Endpoint/Uncertainty Factor:  

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 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. Absorption via
inhalation is assumed to be equivalent to absorption via the oral route.

3.3.8	Level of Concern for Margin of Exposure  TC \l3 "3.5.8	Level of
Concern for Margin of Exposure 

Table 3.3.8.  Summary of Levels of Concern for Clothianidin 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	1000	1000	1000

Inhalation	1000	1000	1000

Incidental Oral	1000	1000	1000



3.3.9	Recommendation for Aggregate Exposure Risk Assessments

As per FQPA, 1996, when there are potential residential exposures to a
pesticide, aggregate risk assessment must consider exposures from three
major sources:  oral, dermal, and inhalation exposures.  The toxicity
endpoints selected for these routes of exposure may be aggregated as
follows: short-, intermediate- and long-term exposures (incidental oral,
dermal, and inhalation exposure) can be aggregated because of the use of
a common endpoint for oral, dermal (oral equivalent) and inhalation
(oral equivalent) routes of exposure.

3.3.10	Classification of Carcinogenic Potential

In accordance with the Draft 1999 Carcinogen Risk Assessment Guidelines,
the HIARC classified clothianidin as “not likely to be carcinogenic to
humans.”  A statistical analysis showed that the increase in thyroid
c-cell tumors in female rats was not significant, especially when
carcinomas and adenomas are 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 is no evidence of
carcinogenicity in rats. There is no evidence of carcinogenicity in
mice.  TC \l3 "3.5.10	Classification of Carcinogenic Potential 

3.3.11	Summary of Toxicological Doses and Endpoints for Clothianidin for
Use in Human Risk Assessments  TC \l3 "3.5.11	Summary of Toxicological
Doses and Endpoints for [Chemical] for Use in Human Risk Assessments 

Table 3.3.11a.  Toxicological Doses and Endpoints for Clothianidin for
Use in Dietary and Non-Occupational Human Health Risk Assessments.

Exposure/

Scenario	Point of Departure	Uncertainty/FQPA Safety Factors	RfD, PAD,
Level of Concern for Risk Assessment	Study and Toxicological Effects

Acute Dietary (General Population, including Infants and Children)
NOAEL= 25 mg/kg/day	UFA= 10x

UFH = 10x

FQPA SF (UFDB)= 10x

	Acute RfD = 0.025 mg/kg/day

aPAD = 0.025 mg/kg/day	Special neurotoxicity/

pharmacology study in mice and rats

LOAEL = 50 mg/kg based on transient signs of decreased spontaneous motor
activity, tremors and deep respirations. 

Acute Dietary

(Females 13-49 years of age)	NOAEL = 25 mg/kg/day	UFA= 10x

UFH = 10x

FQPA SF (UFDB)= 10x

	Acute RfD = 0.025 mg/kg/day

aPAD = 0.025 mg/kg/day	Developmental rabbit study

LOAEL = 75 mg/kg/day based on an increased litter incidence of a missing
lobe of the lung

Chronic Dietary (All Populations)	NOAEL= 9.8 mg/kg/day	UFA= 10x

UFH = 10x

FQPA SF (UFDB)= 10x

	Chronic RfD = 0.0098

mg/kg/day

cPAD = 0.0098 mg/kg/day	Two-generation reproduction study 

LOAEL = 31.2 mg/kg/day based on decreased mean body weight gain and
delayed sexual maturation, decreased absolute thymus weights in F1 pups
and an increase in stillbirths in both generations. 

Incidental Oral (All Durations)	NOAEL= 9.8 mg/kg/day	UFA= 10x

UFH = 10x

FQPA SF (UFDB)= 10x

	Residential LOC for MOE = 1000	Two-generation reproduction study 

LOAEL = 31.2 mg/kg/day based on decreased mean body weight gain and
delayed sexual maturation, decreased absolute thymus weights in F1 pups
and an increase in stillbirths in both generations.

Dermal 

(All Durations)	NOAEL= 9.8  mg/kg/day

Dermal absorption rate = 17%	UFA= 10x

UFH = 10x

FQPA SF (UFDB)= 10x

	Residential LOC for MOE = 1000	Two-generation reproduction study 

LOAEL = 31.2 mg/kg/day based on decreased mean body weight gain and
delayed sexual maturation, decreased absolute thymus weights in F1 pups
and an increase in stillbirths in both generations.

Inhalation

(All Durations)	NOAEL = 9.8 mg/kg/day

Inhalation absorption rate =  100%	UFA= 10x

UFH = 10x

FQPA SF (UFDB)= 10x

	Residential LOC for MOE = 1000	Two-generation reproduction study 

LOAEL = 31.2 mg/kg/day based on decreased mean body weight gain and
delayed sexual maturation, decreased absolute thymus weights in F1 pups
and an increase in stillbirths in both generations.

Cancer (oral, dermal, inhalation)	Classification:  “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).  UFDB = to account for the absence of key data (i.e.,
lack of a developmental immunotoxicity 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.

Table 3.3.11b.  Summary of Toxicological Doses and Endpoints for
Clothianidin for Use in Occupational Human Health Risk Assessments.

Exposure/

Scenario	Point of Departure	Uncertainty Factors	Level of Concern for
Risk Assessment	Study and Toxicological Effects

Dermal 

(All Durations)	NOAEL=9.8 mg/kg/day

Dermal absorption rate = 17%	UFA=10x

UFH=10x	Occupational LOC for MOE = 100	Two-generation reproduction study


LOAEL = 31.2 mg/kg/day based on decreased mean body weight gain and
delayed sexual maturation, decreased absolute thymus weights in F1 pups
and an increase in stillbirths in both generations.

Inhalation

(All Durations)	NOAEL=9.8 mg/kg/day

Inhalation absorption rate =  100%	UFA=10x

UFH=10x	Occupational LOC for MOE = 100	Two-generation reproduction study


LOAEL = 31.2 mg/kg/day based on decreased mean body weight gain and
delayed sexual maturation, decreased absolute thymus weights in F1 pups
and an increase in stillbirths in both generations.

Cancer (oral, dermal, inhalation)	Classification:  “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).  MOE = margin of exposure.  LOC = level of concern.

3.4	Endocrine disruption

EPA is required under the Federal Food Drug and Cosmetic Act (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 has 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 endocrine disruption.

4.0	Public Health and Pesticide Epidemiology Data

  TC \l1 "4.0	Public Health and Pesticide Epidemiology Data 

4.1	Incident Reports

There are currently no incident reports for clothianidin (H. Allender,
8/29/2006).

4.2	National Health and Nutritional Examination Survey (NHANES) 

Clothianidin is not currently included in the NHANES database (R. Allen,
8/23/2006).

4.3	Agricultural Health Study (AHS) 

Clothianidin is not currently included in the AHS database (R. Allen,
8/23/2006).

4.4	Other Pesticide Epidemiology Published Literature

No public health or epidemiology data were found for this chemical when
the National Library of Medicine TOXNET and PubMed databases were
searched (K. Schumacher, 9/20/2007  TC \l2 "4.4	Other Pesticide
Epidemiology Published Literature ).

5.0	Dietary Exposure/Risk Characterization

HED MARC Decision Memo (D282449, Y. Donovan, 4/25/2003)

HED Residue Chemistry Summary Document (D335355, W. Drew, DRAFT)

EFED Estimated Environmental Concentrations (D299401 and D301729, L.
Liu, 7/6/2004)

HED Dietary Exposure Memo (D343102, W. Drew, DRAFT)

5.1	Pesticide Metabolism and Environmental Degradation  TC \l2 "5.1 
Pesticide Metabolism and Environmental Degradation 

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.  Based on these 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 in risk
assessment and the tolerance expression for primary crops.  However, HED
also determined that future new uses on root crops and/or leafy
vegetables will require analysis for residues of TMG along with parent
in field trial samples.  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.  TC \l3
"5.1.1	Metabolism in Primary Crops 

5.1.2	Metabolism in Rotational Crops

Adequate confined and limited field rotational crop studies are
available to support the proposed maximum use rate and proposed use
directions on sugar beets.  The metabolism of clothianidin in primary
and rotational crops is similar.  The MARC concluded that parent, TZNG,
and MNG are the ROCs in rotational crops and that only parent needs to
be included in 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.    TC
\l3 "5.1.3	Metabolism in Livestock For ruminants, the MARC concluded
that the ROCs for risk assessment include parent and the metabolites
TZU, TZG, TZNG, and ATMG-Pyruvate; for poultry, the MARC concluded that
the ROCs for risk assessment include parent and the metabolites TZU,
TZG, TZNG, and ATG-Acetate.  However, for purposes of tolerances, the
MARC recommended that only parent needs to be included in the tolerance
expression.  

5.1.4	Analytical Methodology

Adequate LC/MS/MS methods are available for both collecting 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.  

In the current sugar beet field trials and processing studies, residues
of clothianidin and its metabolite, TMG, were determined in each
commodity using an LC/MS/MS method (Bayer Method TI-002-P05-001).  This
method is similar to the enforcement methods, but it also determines
residues of TMG.  For this method, residues are extracted sequentially
with acetonitrile (ACN) and ACN/water, then fortified with
[2H6]-internal standards of clothianidin and TMG.  Residues are then
acidified, purified using a C18 solid-phase extraction (SPE) cartridge,
and determined by LC/MS/MS.  Residues of clothianidin and TMG are
expressed in clothianidin equivalents.  The method was adequately
validated in conjunction with the analysis of study samples.  The
validated LOQ for both clothianidin and TMG is 0.010 ppm in sugar beet
roots, tops, and processed fractions, with the exception of clothianidin
in molasses (0.020 ppm).  The statistically calculated limits of
detection (LODs) for clothianidin are 0.003 ppm in roots, tops, refined
sugar, and dried pulp, and 0.011 ppm in molasses.  The statistically
calculated LODs for TMG are 0.001 ppm in roots, 0.002 ppm in refined
sugar and dried pulp, 0.003 ppm in tops, and 0.005 ppm in molasses.  

Multiresidue method testing of clothianidin and its metabolites MNG,
TZG, TZNG, TZU, and ATMG-Pyr have been submitted (D282446, Y. Donovan,
5/1/2003).  However, it was determined that clothianidin and its major
metabolites are not adequately recovered using any of the multiresidue
methods.  These data were forwarded to the US FDA for further
evaluation.  

5.1.5	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.
  TC \l3 "5.1.5	Environmental Degradation 

5.1.6	Pesticide Metabolites and Degradates of Concern TC \l3 "5.1.8
Pesticide Metabolites and Degradates of Concern 

Table 5.1.6.  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

Plants

	Primary Crop	Parent

(For Sugar Beet Tops only:  Parent and TMG1)	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

1 Although TMG is a residue of concern to include in risk assessment for
sugar beet tops, this is no longer a regulated food or significant feed
item.

5.1.7	Drinking Water Residue Profile

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.  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.  The MARC's decision on residues
of concern for thiamethoxam in drinking water is parent only.  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 calculations and 1.35 ppb for chronic risk and cancer risk
calculations.  Clothianidin EDWCs in groundwater are not expected to
exceed 5.84 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 5.84 ppb from
groundwater for chronic exposures).  As an added conservatism in this
chronic assessment, the acute 7.29 ppb EDWC from surface water was used
for both the acute and chronic analyses.

Table 5.1.7.  Summary of Estimated Surface Water and Groundwater
Concentrations for Clothianidin.

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

Acute	7.29	5.84

Chronic (non-cancer)	1.35	5.84

Chronic (cancer)	N/A	N/A

a From the Tier 1 FIRST model assuming a maximum applicate rate of 0.4
lb a.i./A, a Koc of 84, and a soil aerobic metabolic half-life of 744
days.

b From the SCI-GROW model. 



5.1.8	Food Residue Profile

The sugar beet field trial data are adequate and support the proposed
use pattern.  Adequate numbers of trials were conducted in the
appropriate geographical regions, and samples were analyzed for both
ROCs using an adequate method.  Provided that the storage stability data
for TMG in sugar beet leaves and potatoes are submitted and deemed
adequate, the sample storage conditions and durations are also supported
by the available storage stability data.  The clothianidin residue data
support the proposed 0.02 ppm tolerance for sugar beet roots.  Although
residue data were also submitted for sugar beet tops, the Agency no
longer considers sugar beet tops to be a significant livestock
feedstuff; therefore, a separate tolerance for tops is not required.  

Residue data from the available limited field rotational crop studies,
conducted at 0.144-0.171 lb ai/A (1.5-1.8X the proposed rate for sugar
beets), adequately support the current tolerances for inadvertent
residues in selected rotational crops.

Provided that the supporting storage stability data are submitted, the
sugar beet processing study is adequate.  The results from the sugar
beet processing study indicate that a separate tolerance is not required
in refined sugar, as clothianidin residues did not concentrate in sugar
(<0.3X).  However, clothianidin residues concentrated by 1.5X in dried
pulp and by 2.9X in molasses.  The maximum possible processing factor
for sugar beet dried pulp is 20X.  Based on HAFT residues of 0.017 ppm
for clothianidin in sugar beet roots and the empirical processing
factors, the maximum expected residues would be 0.026 ppm in dried pulp
and 0.049 ppm in molasses.  These data would support tolerances of 0.03
ppm in dried pulp and 0.05 ppm in molasses.  

Tolerances for clothianidin residues in animal commodities were recently
reassessed in conjunction with petitions for uses on grapes, potatoes,
sorghum, and cotton (D309473; William Drew; 2/1/2006).  As the proposed
sugar beet tolerances do not alter the theoretical dietary burden of
livestock for clothianidin residues, reassessment of animal tolerances
is not required for this petition, and the current tolerance in milk is
adequate.  

5.1.9	International Residue Limits

Regarding international MRLs for clothianidin, harmonization of the
proposed tolerances for sugar beet roots, molasses, and dried pulp is
not an issue; as of September 2007, there are no established or proposed
Canadian, Mexican, or Codex MRLs for clothianidin residues on sugar beet
commodities.

5.2	Dietary Exposure and Risk

HED Dietary Exposure Memo (D343102, W. Drew, DRAFT)

luation Model (DEEM-FCID™, Version 2.03).  Clothianidin has been
classified as “not likely” carcinogenic; therefore, cancer risk from
exposure to clothianidin is not of concern.  Clothianidin is a major
metabolite of the active ingredient thiamethoxam and residues of
clothianidin coming from thiamethoxam were accounted for in these
assessments.  All registered, pending, and proposed uses of
thiamethoxam, as of the date of this memorandum, are included in these
assessments.  The acute assessment is based on maximum residues of
clothianidin observed in clothianidin and thiamethoxam field trials and
assumes 100% crop treated (%CT).  The chronic assessment is based on
average residues from clothianidin and thiamethoxam field trials and
also assumes 100% crop treated.  For crops that are registered for both
thiamethoxam and clothianidin, residues were estimated by combining
values from both sources of clothianidin.  Assuming 100% crop treated in
these analyses results in a potential “double counting” of
clothianidin coming from thiamethoxam for crops that have registered
uses of both compounds, since the label for clothianidin does not permit
application of another "Group 4A" insecticide (e.g., thiamethoxam)
following application of clothianidin.  Therefore, this method of
accounting for thiamethoxam’s involvement in clothianidin exposure
likely overestimates that particular contribution to total exposure. 
The empirical processing factor for apple juice is used for apple and
pear juice, and empirical factors were used for grape juice, raisins,
and sugar beet molasses; otherwise, DEEM default processing factors are
used.  The analyses include direct incorporation of estimated
clothianidin residues in drinking water.  For water, the highest acute
estimate from conservative models was used for both the acute and the
chronic dietary exposure analyses.

Based on these highly conservative assumptions, acute dietary risk
estimates at the 95th percentile of exposure are less than or equal to
45% of the acute population-adjusted dose (aPAD) for all population
subgroups.  Children 1 to 2 years of age were the most highly exposed
subgroup, utilizing 45% of the aPAD, while the general US population
utilized 11% of the aPAD.  Chronic dietary risk estimates are less than
or equal to 16% of the chronic population-adjusted dose (cPAD) for all
population subgroups.  Children 1 to 2 years of age were again the most
highly-exposed subgroup, utilizing 16% of the cPAD, while the general US
population utilized 5% of the cPAD.  Generally, HED is concerned when
risk estimates exceed 100% of the PAD; therefore, all acute and chronic
dietary risk estimates are below HED’s level of concern (LOC).  

 TC \l2 "5.2  Dietary Exposure and Risk 

5.2.1	Acute Dietary Exposure/Risk

Table 5.2.1.  Summary of the Acute Dietary Exposure and Risk Estimates
for Clothianidin.

Population Subgroup	Acute PAD (mg/kg/day)	Acute Estimates

(95th Percentile)



Dietary Exposure (mg/kg/day)	% aPAD

General U.S. Population	0.025	0.002813	11

All Infants (< 1 year old)	0.025	0.007806	31

Children 1-2 years old	0.025	0.011227	45

Children 3-5 years old	0.025	0.007231	29

Children 6-12 years old	0.025	0.003085	12

Youth 13-19 years old	0.025	0.001403	6

Adults 20-49 years old	0.025	0.001902	8

Adults 50+ years old	0.025	0.002102	8

Females 13-49 years old	0.025	0.001975	8

  TC \l3 "5.2.1  Acute Dietary Exposure/Risk 

Chronic Dietary Exposure/Risk

Table 5.2.2.  Summary of the Chronic Dietary Exposure and Risk Estimates
for Clothianidin.

Population Subgroup	Chronic PAD (mg/kg/day)	Source of Clothianidin



Clothianidin	Thiamethoxam	Total



Dietary Exposure (mg/kg/day)	% cPAD	Dietary Exposure (mg/kg/day)	% cPAD
Dietary Exposure (mg/kg/day)	% cPAD

General U.S. Population	0.0098	0.000368	4	0.000105	1	0.000473	5

All Infants (< 1 year old)	0.0098	0.001083	11	0.000179	2	0.001262	13

Children 1-2 years old	0.0098	0.001315	13	0.000263	3	0.001578	16

Children 3-5 years old	0.0098	0.000921	9	0.000223	2	0.001144	12

Children 6-12 years old	0.0098	0.000447	5	0.000142	2	0.000589	6

Youth 13-19 years old	0.0098	0.000222	2	0.000095	1	0.000317	3

Adults 20-49 years old	0.0098	0.000273	3	0.000084	1	0.000357	4

Adults 50+ years old	0.0098	0.000300	3	0.000085	1	0.000385	4

Females 13-49 years old	0.0098	0.000279	3	0.000081	1	0.000360	4



5.3	Anticipated Residue and Percent Crop Treated (%CT) Information

The acute assessment is based on maximum residues of clothianidin
observed in clothianidin and thiamethoxam field trials and assumes 100%
crop treated.  The chronic assessment is based on average residues from
clothianidin and thiamethoxam field trials and also assumes 100% crop
treated.  For crops that are registered for both thiamethoxam and
clothianidin, maximum field-trial residues (acute assessment) or average
field trial residues (chronic assessment) were combined for each crop
(i.e., clothianidin from clothianidin field trials + clothianidin from
thiamethoxam field trials).  TC \l2 "5.3 Anticipated Residue and Percent
Crop Treated (%CT) Information 

6.0	Residential (Non-Occupational) Exposure/Risk Characterization

HED Occupational/Residential Exposure Memo, (D296176, M. Dow, 2/24/2004)

HED Occupational/Residential Exposure Memo, (D340131, S. Oonnithan,
6/28/2007)

Residential (non-occupational) exposure to clothianidin results solely
from currently registered use of this compound, with no additional
residential exposure expected from the proposed new use on sugar beet
seeds.  Refer to the risk assessment for use on turfgrass (D304499, W.
Cutchin, 1/6/2005) or to the corresponding residential exposure
assessment (D296176, M. Dow, 2/24/2004) for more details.

Subsequent to the risk assessment on the residential exposure to
clothianidin, thiamethoxam has been registered for use on turf.  Because
the actions of these compounds are similar and because the thiamethoxam
label recommends against the application of another Group 4A
insecticide, it is highly unlikely that turf would be treated with
thiamethoxam and clothianidin simultaneously.  Since the duration of
residential exposure to either compound is short-term, simultaneous
exposure to clothianidin from both sources is highly unlikely. 
Residential exposure to clothianidin applied directly on turf is
expected to be higher than exposure to clothianidin residues when
thiamethoxam is applied on turf, so previously calculated risks for the
use of clothianidin, per se, on turf are considered protective of
residential exposure to clothianidin as either an active ingredient or a
metabolite of thiamethoxam.  

6.1	Residential Handler Exposure

Although residential handler exposure is not expected from the currently
registered or proposed uses of clothianidin, due to the absence of
products registered or proposed for homeowner use, the exposure
estimates in Table 6.2 do include adult exposure from application with a
granular push-type spreader.  Therefore, this represents an overestimate
of total exposure. TC \l2 "6.1	Residential Handler Exposure 

6.2.	Residential Post-application Exposure

Based on the registered use patterns on turfgrasses, a number of
residential or recreational post-application exposures are possible.  In
a residential setting, a “homeowner” may be exposed during
application of the material to his or her lawn (although not in the case
of clothianidin, due to the absence of products registered or proposed
for homeowner use).  Further, the “homeowner” may also experience
post-application dermal exposure.  Toddlers may be exposed via
“hand-to-mouth” oral exposures and/or dermal exposures.  These
estimated exposures and risks are also presented.  “Aggregated”
exposures are presented for toddlers (i.e., hand-to-mouth turf +
hand-to-mouth soil + dermal post-application).  Hand-to-mouth ingestion
of granules is considered episodic in nature, that is, a “one-time”
event.  Therefore the exposure from ingestion of granules is not
combined with believed multiple exposures from “mouthing” of turf or
soil or from post-application dermal exposure.  Golfers may be exposed
to post-application residues, and estimates of adult and adolescent
golfer exposures are presented.

It is HED’s policy to routinely conduct screening level assessments
(based on standard values in the Residential SOPs) for children’s
incidental ingestion of granules, when a granular pesticide may be
applied in residential settings.  The screening-level assessment for
clothianidin resulted in an MOE of 250 and is a risk of concern.  Based
on information provided by Arysta (email from Doina Bujor dated
11/27/2006) on the particle volumes of the granular clothianidin
formulations, HED agrees that there is little exposure potential for
children’s incidental ingestion of clothianidin granules.  The
particle size is relatively small, and if used according to label
directions, it is unlikely that clothianidin granules would be
accessible to a child.

The MOEs for the residential post-application exposures/risks range from
1,300 to 490,000 (Table 6.2).  MOE values greater than 1000 are
considered adequate to protect adults and children from residential
post-application exposures to clothianidin.  The estimated MOEs are
based upon conservative assumptions and are >1000; therefore, the
estimated risks from residential post-application exposures do not
exceed HED’s level of concern.

Table 6.2.  Summary of Residential Exposure and Risk Estimates for
Clothianidin.

Activity	Exposure

(mg a.i./kg bw/day)	MOE

Toddler oral hand to mouth from contacting treated turf	0.0059	1700

Toddler incidental oral ingestion of treated soil	0.00002	490000

Adult dermal post applic turf contact	0.00108	9100

Adult combined dermal exposure = application + postapplication
application            0.000026

post-application +  0.00108	8900

Toddler dermal post applic turf contact	0.00155	6300

Toddler combined oral (except granules) and dermal exposures	treated
turf + treated soil + dermal

0.00747	1300

Adult golfer post app turf contact	0.000075	130000

Child golfer post app turf contact	0.000128	77000



6.3	Other (Spray Drift, etc.)

Spray drift is a potential source of exposure to residents nearby to
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.  On a chemical by chemical basis, 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 database 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.   TC \l2 "6.3	Other (Spray Drift,
etc.) 

6.4	Exposure from Use of Tobacco

Exposure to clothianidin from use of tobacco has been addressed in a
previous risk assessment (D304499, W. Cutchin, 1/6/2005) and is not
re-examined in this document.

7.0	Aggregate Risk Assessments and Risk Characterization

In accordance with the FQPA, HED must consider and aggregate pesticide
exposures and risks from three major sources:  food, drinking water, and
residential exposures.  In an aggregate assessment, exposures from
dietary and residential sources are added together and compared to
quantitative estimates of hazard (e.g., a NOAEL), or the risks
themselves can be aggregated.  When aggregating exposures and risks from
various sources, HED considers both the route and duration of exposure.

Short- and intermediate-term aggregate risk assessment is required for
clothianidin due to potential residential and/or recreational exposures
to residues on turfgrass.

7.1	Acute Aggregate Risk

Estimates of pesticide residues in drinking water were incorporated
directly into the dietary exposure analysis to assess aggregate acute
risk.  Therefore, the acute aggregate risk estimates are equivalent to
the acute dietary risk estimates provided in Table 5.2.1.  The acute
aggregate risks associated with the registered and proposed uses of
clothianidin do not exceed HED’s level of concern for the general U.S.
population or any population subgroup.

7.2	 TC \l2 "7.1	Acute Aggregate Risk  TC \l2 "7.1	Acute Aggregate Risk
Short- and Intermediate-Term Aggregate Risk

The HIARC has determined that, for clothianidin, the toxicological
effects are the same across oral, dermal, and inhalation routes of
exposure and has selected the same endpoint and dose for short- and
intermediate-term exposure scenarios.  Therefore, the exposures are
simply summed (combined/aggregated) for use in risk calculations. 
Short- and intermediate aggregate risk estimates range from an MOE of
1,100 for toddlers (food + water + treated turf + treated soil + dermal)
to 22,000 for youth golfers (food + water+ post-application treated
turf).  The short- and intermediate-term aggregate risks associated with
the registered and proposed uses of clothianidin do not exceed HED’s
level of concern for the general U.S. population or any population
subgroup.

Table 7.2.  Short- and Intermediate-Term Aggregate Risk Calculations for
Clothianidin.

Population	NOAEL

(mg/kg/day)	LOC1	Average

Food & Water Exposure

(mg/kg/day)	Residential Exposure2

(mg/kg/day)	Aggregate MOE [food, water, and residential]3

Toddler	9.8	1000	0.001578	0.007470	1100

Females 13-49	9.8	1000	0.000360	0.001106	6700

Adult (male)	9.8	1000	0.000473	0.001106	6200

Adult golfer	9.8	1000	0.000473	0.000075	18000

Youth golfer	9.8	1000	0.000317	0.000128	22000

1  The Level of Concern is based on the following uncertainty factors: 
10X for interspecies variability, 10X for intraspecies variability, and
10X for database uncertainty for the lack of a developmental
immunotoxicity study.

2  Residential Exposure = [oral exposure + dermal exposure + inhalation
exposure].  See Table 6.2.

(Avg Food & Water Exposure + Residential Exposure)]

7.3	Long-Term Aggregate Risk

Long-term residential exposure to clothianidin (i.e., >6 months) is not
considered likely to occur.  Estimates of pesticide residues in drinking
water were incorporated directly into the dietary exposure analysis to
assess aggregate chronic risk.  Therefore, the long-term aggregate risk
estimates are equivalent to the chronic dietary risk estimates provided
in Table 5.2.2.  As previously noted, clothianidin is a metabolite of
the active ingredient thiamethoxam and exposures to clothianidin due to
thiamethoxam uses were considered in the chronic dietary assessment. 
The long-term aggregate risks associated with clothianidin exposure
resulting from the registered and proposed uses of clothianidin and from
the registered uses of thiamethoxam do not exceed HED’s level of
concern for the general U.S. population or any population subgroup.

7.4	Cancer Risk

Clothianidin has been classified by HED HIARC as a “not likely human
carcinogen.”   As such, cancer risk from clothianidin is not of
concern to HED.

8.0	Cumulative Risk Characterization/Assessment

Clothianidin is a member of the neonicotinoid class of pesticides and is
a metabolite of another neonicotinoid, thiamethoxam.  Structural
similarities or common effects do not 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 nicotinic acetylcholine receptors,
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 (e.g., testicular tubular atrophy with thiamethoxam;
mineralized particles in thyroid colloid with imidaclopid).  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 EPA’s Office
of Pesticide Programs on EPA’s website at   HYPERLINK
"http://www.epa.gov/pesticides/cumulative/" 
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.  For agricultural uses, EPA has taken the further
conservative step of assuming that, in instances where both thiamethoxam
and clothianidin are registered for use on a crop, both pesticides will,
in fact, be used on that crop in the same growing season, despite
resistance-management labeling to the contrary.

9.0	Occupational Exposure/Risk Pathway

HED Occupational/Residential Exposure Memo, (D340131, S. Oonnithan,
6/28/2007)

Poncho Beta (EPA File Symbol: 264-RNLA), a new flowable concentrate
containing 34.3% clothianidin (3.33 lb ai/gal) and 4.6% beta-cyfluthrin
(0.44 lb ai/gal) as active ingredients, is proposed for the seed
treatment of sugar beets to control early season insect pests.  The
petitioner is proposing to treat sugar beet seeds with undiluted Poncho
Beta in a commercial facility using liquid or slurry coating equipment
at the rate of 5.07 fl. oz. of product per 1 unit of sugar beet seeds,
amounting to 0.032 lb ai/lb of seed.  The treated seeds are bagged and
stored until used.

The petitioner has not submitted any product-specific exposure data for
estimating the risk to handlers; therefore, the default values from
HED's generic databases, such as Pesticide Handlers  Exposure Database
(PHED) and Science Advisory Committee on Exposure (ExpoSAC) Policies
were used to calculate the occupational exposures to loaders,
applicators, and other seed treatment (ST) workers.

9.1	Short- and Intermediate-Term Handler Risk

The treatment of sugar beet seeds may last more than a month due to the
longer planting season; therefore, both short-term (1-30 days) and
intermediate-term (1-6 months) occupational exposures were assessed. 
The liquid Poncho Beta formulation is used without any dilution, and the
ST process is expected to result in the following exposure scenarios:

loader/treater who transfers the formulation and treats the seeds (in
some ST scenarios, loading and treating may be performed by the same or
separate individuals)   

bagger of treated seeds

sewer of bags containing treated seeds

workers doing multiple activities (in a small ST setup, all the
operations may be performed by the same worker).

Summaries of the handler exposures/risks from sugar beet seed treatment
are presented in Table 9.  Since the NOAELs for the dermal and
inhalation routes of exposure and durations of exposure are the same,
the total MOEs (Table 9) represent both the short- and intermediate-term
risks.  A total MOE of 100 or more is sufficient to protect workers from
all of the occupational handler exposures to clothianidin.  Risk
estimates calculated for the seed treatment handlers are below the level
of concern for all workers who wear baseline PPE (MOEs = 170 to 1400),
with the highest risk for those workers who do multiple operations on a
daily basis.  Use of chemical resistant gloves and dust/mist
respirators, which is a label requirement for all workers involved in ST
of sugar beet seeds, is expected to provide additional protection from
exposure to the pesticide active ingredients in Poncho Beta.  

9.2	Short-Term Post-application Risk

It is assumed that the sugar beet planting season may last more than 30
days/year, resulting in both short- and intermediate-term
post-application exposures.  However, because the dermal toxicity doses
(NOAELs) are the same for short- and intermediate-term exposures, the
MOEs are also the same for both exposure durations.

The postapplication exposure to clothianidin is likely while farm
workers transfer the treated seed from bags to planter-hopper and while
planting/drilling the seed.  HED has determined that the handling and
planting of treated sugar beet seeds involve negligible exposure as long
as the treated seeds are not contacted directly.  A likely exposure
scenario for planters handling and planting treated seeds indicated that
the risk is not of concern.  Additionally, the label requires handlers
of Poncho Beta seed bags that were treated prior to planting to wear
basic PPE, which should further minimize any dermal exposure to
clothianidin.  Even though no PPE is recommended for planters while
seeding/planting, no direct contact with treated seed is expected, as
the planting machinery places/drills the seed and covers it with soil,
doing both steps in one operation.  Covering treated seeds with soil
protects workers who may reenter a field soon after planting for
irrigation.  No other postapplication activity is performed in a freshly
seeded sugar beet field.  There is no restricted entry interval (REI)
for treating and planting of pre-treated seeds as REI is not applicable
for ST operations.

The handler and postapplication risks estimated in this assessment are
assumed to be representative of high-end exposures.  The exposures for
handlers and farmers are based on a central tendency estimate of unit
exposure and an upper-percentile assumption for the application rate. 
The uncertainties associated with this assessment stem from the
assumptions regarding the amount of chemical handled and the amount of
seed treated/planted per day.  The estimated exposures are believed to
be reasonable high-end estimates based on observations from field
studies and professional judgment.

An MOE of 100 or more is sufficient to protect workers from
post-application occupational exposures to clothianidin.  The
post-application risk estimate for sugar beet seed planters is below the
level of concern at the baseline level (MOE = 4,800).  This estimate is
presented in Table 9.



Table 9.  Short- and Intermediate-Term Risks to Workers and Planters
Resulting From the Seed Treatment of Sugar Beet with Poncho Beta
Containing 	  Clothianidin.

Exposure 

Scenarios	

PPE 1	Qty Treated or Planted/day (lbs)	Unit Exp. Dermal/day

(mg/lb ai)	Unit Exp. Inhal./day

(µg/lb ai)	Dermal 

Dose/day

(mg/kg) 2 	Inhal.

Dose/day

(mg/kg)2	

Total                    MOE 3

Treatment: 

Loading/Treating	S, G	52,000	0.023	0.34	0.00644	0.00952	610

Bagging, treated seed	S	52,000	0.0091	0.16	0.00255	0.00448	1,400

Sewing, bagged seed	S	52,000	0.0062	0.23	0.00174	0.00644	1,200

Doing multiple jobs	S, G	52,000	0.0420	1.6	0.01176	0.04479	170

Post-treatment:                           - Planting of treated seeds 	

S #  	

640	

0.25	

3.4 	

0.00086	

0.00117	

4,800

1.  S = Single layer (long sleeve shirt and long pants) and no gloves, G
= chemical resistant gloves.  

2.  Dermal dose =  [unit dermal exposure * dermal absorption (%/100) *
application rate * area treated/day] / body weight. 

     Inhalation dose = [unit exposure * (µg/1000) mg conversion factor
* dermal absorption (%/100) * application rate * area treated/day] /
body weight.

3.  Total MOE = NOAEL / (Dermal dose + Inhalation dose).  Total MOE
represents both the short- and intermediate-term risks.

#.  For handlers/planters, gloves are to be used for loading only.

 

10.0	Data Needs and Label Recommendations  TC \l1 "10.0	Data Needs and
Label Requirements 

10.1	Toxicology  TC \l2 "10.1	Toxicology 

Developmental immunotoxicity study

10.2	Residue Chemistry

To support the stability of TMG residues in sugar beet commodities, the
petitioner cited data from an ongoing study examining the stability of
TMG in frozen sugar beet leaves, and potato tubers, flakes, and chips. 
These data should be submitted for evaluation.

10.3	Occupational and Residential Exposure  TC \l2 "10.3	Occupational
and Residential Exposure 

None

References:

  TC \l1 "References: 

HED Clothianidin Risk Assessment (D304499, W. Cutchin, 1/6/2005)

HED DIT Waiver Request Memo (D318520, K. Schumacher, 10/17/2006)

HED MARC Decision Memo (D282449, Y. Donovan, 4/25/2003)

HED Residue Chemistry Summary Document ((D335355, W. Drew, 10/16/2007)

EFED Estimated Environmental Concentrations (D299401 and D301729, L.
Liu, 7/6/2004)

HED Dietary Exposure Memo (D343102, W. Drew, 10/16/2007)

HED Occupational/Residential Exposure Memo, (D340131, S. Oonnithan,
6/28/2007)

HED Occupational/Residential Exposure Memo, (D296176, M. Dow, 2/24/2004)


Appendix A:  Toxicology Assessment  TC \l1 "Appendix A:  Toxicology
Assessment 

A.1	Toxicology Data Requirements TC \l2 "A.1  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		yes

yes	yes

yes

Special Studies

Developmental Immunotoxicity		

yes	

no

A.2	Toxicity Profiles

Table A.2.1	Acute Toxicity Profile - Clothianidin Technical,
Intermediates, and Metabolites

  SEQ CHAPTER \h \r 1 Test Material	Guideline No.	Study Type	MRID(s)
Results	Toxicity Category

  SEQ CHAPTER \h \r 1 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-CCMT-

Adduct Intermediate	870.1100	Acute oral - rat	45422630	LD50 > 2000 mg/kg
(♂+♀)	III

Clothianidin-Hexahydropyrimidine 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. =   SEQ CHAPTER \h \r 1 384-561)

LD50 = 425 mg/kg (♂+♀;

95% C.I. =   SEQ CHAPTER \h \r 1 380-475)	II

Technical	870.1200	Acute dermal - rat	45422634	LD50 > 2000 mg/kg	III

Technical	870.1300	Acute inhalation	45422636	LC50 >   SEQ CHAPTER \h \r
1 5.538 mg/L (♂+♀)	IV

Technical	870.2400	Acute eye irritation	45422701	  SEQ CHAPTER \h \r 1
Slightly irritating to the eye	IV

Clothianidin-CCMT- Adduct Intermediate	870.2400	Acute eye irritation
45422814	  SEQ CHAPTER \h \r 1 Not irritating to the eye	IV

Clothianidin-Triazan Intermediate	870.2400	Acute eye irritation	45422819
  SEQ CHAPTER \h \r 1 Not irritating to the eye	IV

Technical	870.2500	Acute dermal irritation	45422703	  SEQ CHAPTER \h \r
1 Not irritating to the skin	IV

Clothianidin-CCMT- Adduct Intermediate	870.2500	Acute dermal irritation
45422813	  SEQ CHAPTER \h \r 1 Not irritating to the skin	IV

Clothianidin-Triazan Intermediate	870.2500	Acute dermal irritation
45422820	  SEQ CHAPTER \h \r 1 Not irritating to the skin	IV

Technical	870.2600	Skin sensitization	45422705	  SEQ CHAPTER \h \r 1 Is
not a sensitizer under conditions of study	N/A

Clothianidin-CCMT- Adduct Intermediate	870.2600	Skin sensitization
45422815	  SEQ CHAPTER \h \r 1 Is not a sensitizer under conditions of
study	N/A

Clothianidin-Triazan Intermediate	870.2600	Skin sensitization	45422821	 
SEQ CHAPTER \h \r 1 Is a sensitizer under conditions of study	N/A



Table A.2.2	Subchronic, Chronic and Other Toxicity Profile

Guideline No. 	Study Type	Results

870.3100

	90-Day oral toxicity - rat	NOAEL =   SEQ CHAPTER \h \r 1 27.9/34.0
mg/kg/day   SEQ CHAPTER \h \r 1 (M/F)    

LOAEL =   SEQ CHAPTER \h \r 1 202.0/254.2 mg/kg/day (M/F) 

based on   SEQ CHAPTER \h \r 1 decreased BW and BW gain.

870.3150

	90-Day oral toxicity - dog	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

	21/28-Day dermal toxicity - rat	NOAEL = 1000 mg/kg/day (HDT)

LOAEL = Not established 

870.3700a

	Prenatal developmental in rodents - rat	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

	Prenatal developmental in nonrodents - rabbit	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.

870.3800

	Reproduction and fertility effects - rat	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.

870.4100a

	Chronic toxicity -rodents	See 870.4300, which includes requirements for
both 870.4100 and 870.4200.

870.4100b

	Chronic toxicity - dog	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 -mouse	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.

870.4300

	Combined chronic feeding/ carcinogenicity - rat	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	  SEQ CHAPTER \h \r 1 Small, but significant increase in
frequency of  histidine revertants in  TA1535 strain treated at 1500 and
5000 ug/plate +/-S9; still present but weaker in its absence.   The
positive response was only reproducible at 5000 ug/plate +/-S9.
Clothianidin considered mutagenic under conditions of this test.

870.5100	Gene Mutation bacterial reverse mutation assay

Parent	No mutagenic activity in bacteria (Salmonella typhimurium and
Escherichia coli) under conditions of this assay.

870.5100	Gene Mutation bacterial reverse mutation assay

Parent	No mutagenic activity in bacteria (Salmonella typhimurium) under
conditions of this assay.

870.5100	Gene Mutation bacterial reverse mutation assay

Parent	Only TA 1535 tested.  No mutagenic activity in bacteria
(Salmonella typhimurium) under conditions of this assay.

870.5100	

Gene Mutation bacterial reverse mutation assay

BN0335E2 metabolite	

No mutagenic activity in bacteria (Salmonella typhimurium) under
conditions of this assay.

870.5100	

Gene Mutation bacterial reverse mutation assay

TZMU metabolite 	

No mutagenic activity in bacteria (Salmonella typhimurium) under
conditions of this assay.

870.5100	

Gene Mutation bacterial reverse mutation assay

methyl guanidine intermediate	

No mutagenic activity in bacteria (Salmonella typhimurium) under
conditions of this assay.

870.5100	

Gene Mutation bacterial reverse mutation assay

TZNG metabolite	

No mutagenic activity in bacteria (Salmonella typhimurium) under
conditions of this assay.

870.5100	

Gene Mutation bacterial reverse mutation assay

TMG metabolite	

No mutagenic activity in bacteria (Salmonella typhimurium) under
conditions of this assay.

870.5100	

Gene Mutation bacterial reverse mutation assay

BN0230M metabolite	

No mutagenic activity in bacteria (Salmonella typhimurium) under
conditions of this assay.

870.5100	

Gene Mutation bacterial reverse mutation assay

MAI metabolite	

No mutagenic activity in bacteria (Salmonella typhimurium) under
conditions of this assay.

870.5100	

Gene Mutation bacterial reverse mutation assay

N-Methylnitroguanidin intermediate	

No mutagenic activity in bacteria (Salmonella typhimurium) under
conditions of this assay.

870.5100	

Gene Mutation - bacterial reverse mutation assay

TI 435-Triazan intermediate	

No mutagenic activity in bacteria (Salmonella typhimurium) under
conditions of this assay.

870.5100	

Gene Mutation - bacterial reverse mutation assay

TI 435-CCMT-Adduct	

No mutagenic activity in bacteria (Salmonella typhimurium) under
conditions of this assay.

870.5300	

Gene Mutation - in vitro mammalian cell gene mutation test (L5178Y TK
+/- mouse lymphoma cells)

Parent	

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)

Parent	

No increase in mutant frequency under the conditions of the study.



870.5395	

Cytogenetics - mammalian erythrocyte micronucleus test

Parent	

Clothianidin is considered to be neither clastogenic nor aneugenic under
these test conditions.



870.5375	

Cytogenetics -  in vitro mammalian chromosome aberration test (CHL
Cells)

Parent	

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.



870.5500	

Other Effects - DNA Repair Test in Bacillus subtillis

Parent	

No potential for DNA damage under these conditions.



870.5550	

Other Effects - (UDS) in Mammalian Cells in Culture

Parent	

No evidence (or a dose related positive response) that UDS was induced.

870.6200a

	Acute neurotoxicity screening battery - rat	NOAEL = Not established

LOAEL = 100 mg/kg/day based on FOB findings (decreased arousal, motor
activity, and locomotor activity).

870.6200b

	Subchronic neurotoxicity screening battery - rat	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.

870.6300

	Developmental neurotoxicity - rat	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 and pharmacokinetics - rat	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,
affirmed the metabolism pathway proposed by the investigators.

870.7485

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摧ᗰԀOf 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
N-demethylation 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	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 (adults)	Immunotoxicity NOAEL = 253
mg/kg/day (M/F)

Immunotoxicity LOAEL = not established

transient signs of decreased spontaneous motor activity, tremors, and
deep respirations.

 TC \l1 " Appendix D:  Review of Human Research 

	Page   PAGE  2  of   NUMPAGES  43 

