UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                         WASHINGTON, D.C. 20460

                                                 	OFFICE OF CHEMICAL SAFETY AND
                                                                                POLLUTION PREVENTION

MEMORANDUM

	Date:	27 September 2012

	SUBJECT:	Clothianidin  -  Aggregate Human Health Risk Assessment of New Uses on Strawberry, Pistachio, and Citrus; New Tolerance for Tea; and Revised PHI and Tolerance for Pepper and Eggplant (Crop Subgroup 8-10B).

PC Code:  044309
DP Barcodes:  D395348, D397647
Decision Nos.: 455249, 459388
Registration No.:  59639-150, 59639-152
Petition No.:  2F8008, 1E7923
Regulatory Action:  Section 3
Risk Assessment Type:  Single Chemical, Aggregate
Case No.:  7620
TXR No.:  None
CAS No.:  210880-92-5
MRID No.:  NA
40 CFR 180.586

	FROM:	Michael A. Doherty, Ph.D., Chemist
		Suku Oonnithan, Ph.D., Biologist
		Edward Scollon, Ph.D., Toxicologist
		Risk Assessment Branch II
		Health Effects Division (7509P)

	THROUGH:	Zaida Figueroa, Industrial Hygenist
		Linnea Hansen, Toxicologist
		Elizabeth Holman, Chemist
		Christina Swartz, Branch Chief
		Risk Assessment Branch II
		Health Effects Division (7509P)

	TO:	Marianne Lewis/Venus Eagle (RM 01)
		Insecticide/Rodenticide Branch
	Registration Division (7505P)

	Barbara Madden
	Risk Integration, Minor Use, and Emergency Response Branch
		Registration Division (7505P)

1.0	Executive Summary	4
2.0	HED Recommendations	4
2.1	Data Deficiencies/Conditions of Registration	4
2.2	Tolerance Considerations	4
2.2.1	Enforcement Analytical Method	4
2.2.2	International Harmonization	5
2.2.3	Recommended Tolerances	5
2.2.4	Revisions to Petitioned-For Tolerances	5
2.3	Label Recommendations	6
2.3.1	Recommendations from Residue Reviews	6
2.3.2	Recommendations from Occupational and Residential Assessments	6
3.0	Introduction	6
3.1	Chemical Identity	6
3.2	Physical/Chemical Characteristics	6
3.3	Pesticide Use Pattern	7
3.4	Anticipated Exposure Pathways	8
3.5	Consideration of Environmental Justice	8
4.0	Hazard Characterization and Dose-Response Assessment	9
4.1	Toxicology Studies Available for Analysis	9
4.2	Absorption, Distribution, Metabolism, & Elimination (ADME)	9
4.2.1	Dermal Absorption	10
4.3	Toxicological Effects	10
4.4	Safety factor for Infants and Children (FQPA Safety Factor)	12
4.4.1	Completeness of the Toxicology Database	13
4.4.2	Evidence of Neurotoxicity	13
4.4.3	Evidence of Sensitivity/Susceptibility in the Developing or Young Animal	13
4.4.4	Residual Uncertainty in the Exposure Database	14
4.5	Toxicity Endpoint and Point of Departure Selections	14
4.5.1	Endpoint Selection	14
4.5.2	Recommendation for Combining Routes of Exposures for Risk Assessment	16
4.5.3	Cancer Classification and Risk Assessment Recommendation	16
4.5.4	Summary of Points of Departure and Toxicity Endpoints Used in Human Risk Assessment	17
5.0	Dietary Exposure and Risk Assessment	18
5.1	Metabolite/Degradate Residue Profile	18
5.2	Food Residue Profile	19
5.3	Water Residue Profile	20
5.4	Dietary Risk Assessment	20
5.4.1	Description of Residue Data Used in Dietary Assessment	20
5.4.2	Percent Crop Treated Used in Dietary Assessment	21
5.4.3	Acute and Chronic Dietary Risk Estimates	21
5.4.4	Dietary Exposure and Risk Estimate Summary Table	22
6.0	Residential (Non-Occupational) Exposure/Risk Characterization	22
6.1	Residential Handler Exposure	22
6.2	Post-Application Exposure	23
6.3	Combined Exposure	24
6.4	Residential Bystander Post-Application Inhalation Exposure	25
6.5	Spray Drift	25
7.0	Aggregate Exposure/Risk Characterization	26
7.1	Acute Aggregate Risk	26
7.2	Short- and Intermediate-Term Aggregate Risk	26
7.3	Chronic Aggregate Risk	27
7.4	Cancer Aggregate Risk	27
8.0	Cumulative Exposure/Risk Characterization	27
9.0	Occupational Exposure/Risk Characterization	28
9.1	Short- and Intermediate-Term Handler Risk	28
9.2	Short- and Intermediate-Term Post-Application Risk	29
9.2.1	Dermal Post-Application Risk	29
9.2.2	Inhalation Post-Application Risk	30
10.0	References	31
Appendix A.  Toxicology Profile and Executive Summaries	32
A.1.  Toxicology Data Requirements	32
A.2.  Toxicity Profiles	33
A.3.  Endpoint Selection	42
Appendix B. Metabolism Summary Table	45
Appendix C.  Physical/Chemical Properties	46
Appendix D.  Review of Human Research	47
Appendix E.  Occupational Exposure/Risk Summary Tables	48
Appendix F.  Summary of Relevant International Residue Limits for Clothianidin.	52

1.0	Executive Summary

The Registration Division (RD) requested that the Health Effects Division (HED) conduct an exposure and risk assessment for a revision to the pre-harvest interval (PHI) for Crop Subgroup 8-10B (peppers and eggplant) proposed by Valent BioSciences and for the IR4 (Inter-Regional Project #4) proposed new uses on strawberry, pistachio, and citrus (Crop Group 10-10), and use on tea without a U.S. registration.  This assessment takes into account previously registered uses on other crops and in residential use sites.

The toxicological database for clothianidin is largely complete; the only missing study is the subchronic (28-day) inhalation toxicity study.  HED has determined that the study is required and has requested its submission during registration review.  Pending the results of the study, a 10X database uncertainty factor has been retained for residential and occupational inhalation exposure assessments.  The residue chemistry database for clothianidin is complete.

HED has evaluated the available hazard and residue chemistry data to derive risk estimates associated with dietary, residential, and occupational exposure.  HED's aggregate risk assessment is based on screening-level assumptions and the resulting estimated exposure levels likely overestimate actual exposures that may occur.  Sentinel aggregate risk indices (ARIs) are 1.21 for children aged 1-2 years old and 6.9 for adults, and are not of concern.  Similarly, occupational ARIs are not of concern, ranging from 1.1 to 660.  Even with the conservative, health-protective assumptions, aggregate and occupational risk estimates are below HED's level of concern for all scenarios and population groups.

There are no human health risk issues that would preclude granting the requested label amendment and new uses, and establishing permanent tolerances as described below.

2.0	HED Recommendations

2.1	Data Deficiencies/Conditions of Registration

A 28-day inhalation toxicity study in rats is required, based on weight of evidence considerations, including the available toxicity data and the potential for exposure to clothianidin via the inhalation route.  The study has been requested under registration review.

2.2	Tolerance Considerations

2.2.1	Enforcement Analytical Method

Adequate methods, based on solvent extraction and LC-MS/MS separation, identification, and quantification, are available for plant (Morse Method #Meth-164 - modified, RM-39C-1, or Bayer Method 00552) and livestock (Bayer Method 00624) matrices.  The LOQ for clothianidin in plant commodities is 0.01 ppm, except for wheat straw (0.02 ppm), and the validated LOQs are 0.01 ppm in milk and 0.02 ppm in animal tissues.  Clothianidin and its major metabolites are not adequately recovered using any of the FDA multiresidue methods.

2.2.2	International Harmonization

There are no Canadian or Codex Maximum Residue Limits (MRLs) for clothianidin that are relevant to the recommended tolerances.  Codex MRLs (see Appendix F) are in place for tea, strawberry, citrus, and fruiting vegetables; however, the MRLs are based on clothianidin derived from treatment with thiamethoxam rather than treatment with clothianidin.  Therefore, it is not appropriate to harmonize U.S. tolerances with the Codex MRLs.

The Pest Management Regulatory Agency (PMRA) of Health Canada intends to establish an MRL for residues in Crop Subgroup 13-07G (low-growing berries) at 1.5 ppm.  Strawberry is the representative crop for this subgroup; therefore, in terms of strawberry, the residue level will be harmonized.  HED is not recommending for the entire subgroup because the requested use was on strawberry only.

With respect to Crop Subgroup 8-10B, the new tolerance for this subgroup is considerably greater than the existing Crop Group 8 tolerance.  The new tolerance will result in regulatory action levels for this subgroup being out of harmonization with PMRA.

2.2.3	Recommended Tolerances

Table 2.2.3.  Summary of Requested and Recommended Tolerances for Residues of Clothianidin.
Commodity
                                Tolerance, ppm
Comments/Corrections

                                   Requested
                                  Recommended

Vegetable, fruiting, peppers and eggplant, Subgroup 8-10B
0.7
0.80
Upon establishment of this tolerance, the existing tolerance listing for vegetables, fruiting, Group 8 should be revised to Vegetable, fruiting, group 8-10, except pepper/eggplant subgroup 8-10B
Pistachio
0.01
0.01
--
Strawberry
1.4
1.50
--
Tea, dried
50
70
--
Fruit, citrus, Group 10-10
0.5
0.60
--
Citrus, dried pulp
1
--
A tolerance for this processed commodity is not necessary.

2.2.4	Revisions to Petitioned-For Tolerances

HED is recommending tolerance levels for Subgroup 8-10B (peppers and eggplant), strawberry, tea, and citrus (including dried citrus pulp) that are different from those requested by the petitioners.  In the case of Subgroup 8-10B, strawberry, and citrus, the difference is likely due to the petitioners' use of the NAFTA MRL calculation procedures rather than the OECD MRL calculation procedures.  The recommended tolerance for residues in/on tea appears to include a broader scope of data than was used to derive the petitioned-for tolerance.  HED has determined that a separate tolerance for the processed commodity dried citrus pulp is not necessary.  Although residues concentrate in dried citrus pulp, it is anticipated that they would not exceed the recommended tolerance level for the whole fruit.

2.3	Label Recommendations

2.3.1	Recommendations from Residue Reviews

   * RD should ensure that the restrictions listed on the proposed label regarding use of adjuvants and restrictions on aerial application reflect all of the recent revisions/recommendations that were made by HED outside of these petitions (e.g., see M. Doherty, D404897, 13 August 2012; M. Doherty, D405080, 5 September 2012).
   * Update the rotational crop restrictions to include strawberry as a crop suitable for immediate plant back.
   * Revise the labels to ensure that for all crops, the maximum amount of active ingredient applied per season is generic for clothianidin and not specific to any one particular end-use product or type of application being made.
   * HED notes that the maximum seasonal foliar use rate for V-10170 2.13 SC on strawberry (0.1 lb a.i./A) differs from the maximum seasonal use rate for the Arena product (0.2 lb a.i./A).  HED recommends that RD ensure that these differences are intended by the petitioner.  The available residue data support a maximum seasonal application rate of 0.2 lb a.i./A to strawberry, irrespective of formulation types.

2.3.2	Recommendations from Occupational and Residential Assessments

None.

3.0	Introduction

3.1	Chemical Identity

Table 3.1.  Clothianidin Nomenclature.
Parent Compound

Common name
Clothianidin
Company experimental name
TI-435, V-10066
IUPAC name
(E)-1-(2-Chloro-1,3-thiazol-5-ylmethyl)-3-methyl-2-nitroguanidine
CAS name
(E)-N-[(2-Chloro-5-thiazolyl)methyl]-N'-methyl-N"-nitroguanidine
CAS registry number
210880-92-5 (formerly 205510-53-8)
Molecular wt.
249.68
End-use product (EP)
50% WDG (Arena[(R)] 50 WDG; EPA Reg. No. 59639-152)
2.13 lb/gal FlC (V-10170 2.13 SC; EPA Reg. No. 59639-150)

3.2	Physical/Chemical Characteristics
APPENDIX C SUMMARIZES THE PHYSICAL AND CHEMICAL PROPERTIES OF CLOTHIANIDIN.  Based on the available data, clothianidin has a low vapor pressure and exposure to this chemical in the vapor phase is not expected.  The octanol/water partitioning coefficient is also quite low, indicating that clothianidin is unlikely to accumulate in fatty tissues.

3.3	Pesticide Use Pattern

Table 3.3.  Summary of Directions for Use of Clothianidin.
                                 Appl. timing,
                              type, and (equip.)
                                  Formulation
                                [EPA Reg. No.]
                            Max. Single Appl. rate
                                   (lb ai/A)
                          Max. No. of Appl. / Season
                    Max. Seasonal Appl. Rate      (lb ai/A)
                                  PHI (days)
                        Use Directions and Limitations
                                  Strawberry
Foliar, ground or aerial (FWA, ground boom and air-blast sprayers)
                               Arena[(R)] 50 WDG
                                  [59639-152]
                                   0.05-0.2
                                       4

                                     0.2
                                       1
RTI=7 days
Soil broadcast, pre- or at transplanting, in-furrow, band or bed,  transplant water drench, drip/trickle irrigation (back pack and MPHG)

                                   0.15-0.2
                                       1
                                      0.2
                                      21
RTI=Not applicable
Foliar, ground or aerial (FWA, ground boom and air-blast sprayers)
                               V-10170  2.13 SC
                                  [59639-150]
                                   0.05-0.1
                                       2
                                      0.1
                                       1
RTI=7 days
Soil in-furrow, band, drench,  drip or trickle irrigation (back pack and MPHG)

                                   0.15-0.2
                                       1
                                      0.2
                                      21
RTI=not applicable
                                 Citrus fruit
Foliar, ground or aerial (aircraft, and air-blast sprayer)
                               V-10170  2.13 SC
                                  [59639-150]
                                   0.05-0.1
                                       4
                                      0.2
                                       1
RTI=14 days
Soil in-furrow, band, drench,  drip or trickle irrigation (back-pack and MPHG)

                                   0.15-0.2
                                       1
                                      0.2
                                      21
RTI=not applicable
Basal bark spray
(back-pack)

                               0.1 for 2-4 ft.
                           and 0.2 for 4-8 ft. trees
                                       1
                                      0.2
                                       1
RTI=not applicable
                                   Nectarine
Foliar, post bloom ground (air blast sprayer)
                               V-10170  2.13 SC
                                  [59639-150]
                                   0.05-0.1
                                       4
                                      0.2
                                      21
RTI=10 days
                                   Pistachio
Foliar, ground or aerial
(FWA and air blast sprayer)
                               V-10170  2.13 SC
                                  [59639-150]
                                   0.05-0.1
                                       4
                                      0.2
                                      21
RTI=10 days
                                      Tea
Foliar
                                      NS
                                      1.8
                                       1
                                      NS
                                       7
Use patterns are implied from the field trial application parameters
                 Peppers and Eggplant (Crop Subgroup 8-10B)[*]
Foliar
                               Arena[(R)] 50 WDG
                                  [59639-152]
                                   0.05-0.1
                                       4
                                      0.2
                                       1
RTI=10 days
Soil in-furrow, band, drench,  drip or trickle irrigation (back-pack and MPHG)

                                   0.15-0.2
                                       1
                                      0.2
                                      NS
Apply at planting
Foliar
                               V-10170  2.13 SC
                                  [59639-150]
                                  0.05-0.067
                                       3
                                      0.2
                                       1
RTI = 7 days
Soil broadcast, pre- or at transplanting, in-furrow, band or bed,  transplant water drench, drip/trickle irrigation (back pack and MPHG)

                                   0.15-0.2
                                       1
                                      0.2
                                      NS
Apply at planting
Abbreviations used: MPHG= mechanically pressurized hand gun, PHI = Preharvest interval, RTI= re-treatment interval, NS=not specified.
* Uses on peppers and eggplant are already registered, with a PHI of 7 days.  This entry reflects the requested label amendment to reduce the PHI to 1 day.

The personal protective equipment (PPE) requirements proposed for applicators and other handlers include:  long-sleeved shirt and long pants, socks plus shoes, and chemical-resistant gloves.  The Restricted Entry Interval (REI) is 12 hours.  The PPE and REI on both labels are appropriate based on the acute toxicity and estimated handler exposures and risks for clothianidin.

3.4	Anticipated Exposure Pathways

Clothianidin is registered for use on numerous agricultural crops as well as on residential turf, and there is also an indoor use to control bed bugs.  Exposure to clothianidin may occur from ingestion of residues in/on foods and in drinking water, and via the dermal and inhalation routes for adults using clothianidin products in occupational and residential settings.  Finally, incidental oral ingestion can occur for toddlers playing in areas previously treated with clothianidin (e.g., turf and indoor surfaces).

3.5	Consideration of Environmental Justice

Potential areas of environmental justice concerns, to the extent possible, were considered in this human health risk assessment, in accordance with U.S. Executive Order 12898, "Federal Actions to Address Environmental Justice in Minority Populations and Low-Income Populations," (http://www.eh.doe.gov/oepa/guidance/justice/eo12898.pdf.  As a part of every pesticide risk assessment, OPP considers a large variety of consumer subgroups according to well-established procedures.  In line with OPP policy, HED estimates risks to population subgroups from pesticide exposures that are based on patterns of that subgroup's food and water consumption, and activities in and around the home that involve pesticide use in a residential setting.  Extensive data on food consumption patterns are compiled by the Dept. of Health and Human Services under the National Health and Nutrition Examination Surveys and are used in pesticide risk assessments for all registered food uses of a pesticide.  These data are analyzed and categorized by subgroups based on age, season of the year, ethnic group, and region of the country.  Additionally, OPP is able to assess dietary exposure to smaller, specialized subgroups and exposure assessments are performed when conditions or circumstances warrant.  Whenever appropriate, non-dietary exposures based on home use of pesticide products and associated risks for adult applicators and for toddlers, youths, and adults entering or playing on treated areas 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.

4.0	Hazard Characterization and Dose-Response Assessment

4.1	Toxicology Studies Available for Analysis

Appendix A summarizes the toxicity profile for clothianidin.  The toxicity database is largely complete, and the following studies are available: acute, subchronic, and developmental neurotoxicity; subchronic oral in rats, mice and dogs; subchronic dermal, chronic/carcinogenicity in rats; carcinogenicity in mice; chronic in dogs; developmental in rats and rabbits; 2-generation reproduction in the rat; mutagenicity battery; metabolism (rats and mice); dermal penetration (monkeys); 28-day immunotoxicity as well as developmental immunotoxicity in the rat; and a special neurotoxicity and pharmacology study in mice.  A complete battery of mutagenicity studies was also conducted with clothianidin and several metabolites.

The only missing toxicology study is a subchronic (28-day) inhalation study, which HED has determined is required, based on weight-of-evidence considerations.

4.2	Absorption, Distribution, Metabolism, & Elimination (ADME)

The ADME of clothianidin was examined in single-dose studies in rats (2.5 and 250 mg/kg) and mice (5 mg/kg) and a 14-day repeated-dose study in the rat (25 mg/kg/day) using radiolabeled chemical.   The rate of absorption, route of excretion, and nature of metabolism was similar across species and gender.  Following an oral dose, greater than 90% of the administered dose is excreted in the urine within the first 24 hours.  At 250 mg/kg/day, there was a lag in urinary clearance, taking up to 48 hours to excrete 90% of the administered dose (AD).  The lag indicates saturation of the absorption mechanism at this high dose.  The remaining 5-6% of the AD is eliminated via the feces.  Females absorbed slightly greater amounts of the administered dose in the rat; 90% for males and 95% for females in the 2.5 mg/kg group.  However, females also had a slightly greater clearance rate so there was not a greater net accumulation in the females.  Females were only tested at the 2.5-mg/kg dose.  The time-to-peak plasma concentrations in the rat (Tmax) were 1.5 and 2.7 hours for the 2.5 and 25 mg/kg dose groups, respectively.

Following absorption, clothianidin is distributed throughout the body.  Although the organs associated with the absorption and elimination systems (i.e., bladder, kidney, liver, and nasal mucosa) initially demonstrate elevated levels, none of the tissues examined contained residue levels >1% of the administered 24 hours after dosing in the rat.  Therefore, bioaccumulation is not a concern.

Parent was the most abundant residue indentified in the urine, at 30% AD in the mouse and 55-74% in the rat.  Three metabolites were identified as major (>10% AD), with several additional metabolites identified at <10% AD.  The major metabolites were the result of demethylation of the parent or cleavage products of the nitrogen-carbon bond between the nitroimino and thiazolyl moieties.

4.2.1	Dermal Absorption

A dermal penetration study was conducted in monkeys, using the undiluted FS 600 formulation of clothianidin (10% ai).  The exposure duration was 8 hours and the subjects were monitored for 120 hours.  Dermal absorption was estimated based on the sum of the administered dose measured in fecal and urinary excretions.  Dermal penetration was low at 0.24% of the administered dose.  A value of 1% dermal absorption has been recommended as appropriate for use in risk assessment (K. Schumacher, D331226, 28 November 2006).

4.3	Toxicological Effects

The insecticidal mode of action of clothianidin is agonism of the nicotinic acetylcholine receptor, leading to overstimulation of the central nervous system and death.  In mammals, the toxic effects of clothianidin appear to be much less specific and involve multiple organ systems.  The primary effects as indicated by the toxicity database are on the liver, hematopoietic system and kidneys.  Liver, body weight changes, thyroid effects and neurotoxicity are all commonly observed in toxicity studies of other neonicotinoids.

Acute neurotoxicity studies were conducted in rats and mice following exposure by gavage.  In the acute neurotoxicity rat study, FOB effects, including decreased arousal as well as decreased motor and locomotor activity, were seen at the lowest observed adverse effect level (LOAEL) on Day 0 in males.  Effects at dose levels above the LOAEL in the rat study included tremors, slightly uncoordinated gait, effects on pupil response and righting reflex, and decreases in both temperature and ataxia.  In the acute neurotoxicity study in mice, effects were also observed on Day 0 in males (no female mice were tested), but occurred at lower doses than those that produced neurotoxic effects in rats.  Effects seen at the LOAEL in the 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, staggered gait, mydriasis, and hypothermia were observed.

In subchronic oral studies in rats and dogs, decreases in body weight and body weight gain were observed.  In addition, dogs also displayed decreased white blood cells, albumin and total protein, as well as some anemia, and they appeared to be more sensitive than rats.  Male dogs were more sensitive than females.  Neurotoxicity was not observed in the subchronic neurotoxicity study.  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 the only adverse effect observed in the dog, and was only found in females at the highest dose tested.  In the rat, decreased body weight and food consumption, interstitial gland hyperplasia in the ovary, increased lymphohistiocytic infiltrate and altered hepatocellular eosinophilic foci of the liver were observed in females; decreased body weight and food consumption, slightly increased incidences of pelvic mineralization, and transitional cell hyperplasia in the kidney, mottled livers, and altered hepatocellular eosinophilic foci in the liver were observed in male rats.  In the mouse, decreases in body weight and body weight gain in females and increases in vocalization in both sexes were the only observed effects.

A comparison of the subchronic and chronic feeding studies in rats showed that a wider spectrum of effects was observed in the chronic study, even though the no observed adverse effect levels (NOAELs) and LOAELs in these two studies were similar.  Thus, it appears that there may be more toxicity in rats when exposure is over a longer period of time.  In contrast, administration to the dog for a longer period of time does not appear to result in any additional effects or effects at lower doses.

No increased quantitative or qualitative susceptibility was observed in the developmental rat or rabbit studies.  In the rat, no developmental toxicity was observed at the highest dose tested, although this dose induced decreases in body weight gain and food consumption in the dams.  In the rabbit, premature deliveries, decreased gravid uterine weights, an increase in litter incidence of a missing lobe of the lung and decreased ossification of the sternum were noted at a dose level at which maternal death, a decrease in food consumption and clinical signs (scant feces and orange urine) were observed.  The developmental effects in this 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.

There was an increase in quantitative susceptibility in the developmental neurotoxicity and reproductive toxicity studies; offspring effects were observed in the absence of maternal toxicity.  In the DNT, maternal effects observed at the high-dose included decreased body weights, body weight gains and food consumption.  Effects seen in the offspring observed at the mid-dose included decreased body weights, body weight gains, motor activity and acoustic startle response in females. In the two-generation reproduction study, 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 at the mid-dose.  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 observed at the high-dose.

Clothianidin is classified as not likely to be carcinogenic to humans.  In the rat chronic carcinogenicity study, an apparent increase in thyroid c-cell tumors was observed in females.  A statistical analysis revealed that the increase in these tumors did not appear to be significant, especially when carcinomas and adenomas were combined.  Increased incidences 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 and no continuum (i.e., no preneoplastic lesions and no adenomas).  There was no evidence of an increase of tumors in mice.

In the mutagenicity studies, none of the intermediates or metabolites appeared to have genotoxic potential under the conditions of the studies, but the studies for the technical material gave mixed results.  Some of the batches of test material were positive and some were negative.  HED had requested that the composition of the test materials used in the mutagenicity studies be investigated to determine whether or not the differences in composition may have affected the results from the studies.  To address the request, additional mutagenicity studies were performed and it was determined that there was no concern because clothianidin was neither clastogenic nor aneugenic in the mouse bone marrow micronucleus assay up to a toxic oral dose (100 mg/kg); also, there was no induction of unscheduled DNA synthesis (UDS) in the livers of Wistar male mice when administered at the limit dose of 2000 mg/kg.

In some of the toxicity studies, there was evidence of possible effects on the immune system.  Decreased absolute and relative thymus and spleen weights were observed in multiple studies.  In addition, juvenile rats in the two-generation reproduction study appeared to be more susceptible to these effects.  The thymus is involved in the production of T cells, whose function is to recognize and respond to foreign antigens.  The spleen serves an important function in clearing the blood of infectious organisms.  A guideline immunotoxicity study showed no evidence of clothianidin-mediated immunotoxicity in adult rats, in the form of a T-cell dependent anti-Sheep Red Blood Cell (SRBC) forming cell response, at doses lower than those resulting in generalized signs of toxicity (e.g., decreases in body weight).  However, since effect in the offspring occurred at lower doses in the two-generation study, HED concluded that the lack of effects on immunotoxicity in adults did not alleviate concerns for immunotoxicity in the offspring.  A developmental immunotoxicity study was required and demonstrated no increased susceptibility with respect to immunotoxicity.

Clothianidin and numerous metabolites were examined for acute toxicity.  Acute toxicity via oral, inhalation and dermal routes of exposure in the rat is relatively low (Category III or IV).  Only technical clothianidin in the mouse and the TMG metabolite in the rat via the oral route were toxicity Category II.  There is no evidence of dermal sensitization or eye irritation with the exception of the clothianidin-triazan intermediate, which is a dermal sensitizer.

4.4	Safety factor for Infants and Children (FQPA Safety Factor)

HED recommends that the FQPA SF of 10X be reduced to 1X for dermal and oral exposure pathways based on the following considerations:  (1) the toxicology data base is complete (with the exception of an inhalation study) and includes developmental neurotoxicity, immunotoxicity and developmental immunotoxicity studies; (2) HED characterized the degree of concern for the quantitative susceptibility observed in the clothianidin 2-generation reproduction and DNT studies as low based on the clear NOAELs for the offspring effects and the selection of regulatory doses that are protective of those effects; (3) the rat is the most sensitive species tested, and the NOAEL and LOAEL selected from the 2-generation reproduction study in rats are protective of effects observed in other species throughout the toxicology database; (4) there are no residual uncertainties for pre- and/or post-natal toxicity, since the submitted developmental immunotoxicity study indicated no evidence of susceptibility; (5) HED is regulating the use of clothianidin based upon the most sensitive offspring effects observed in the reproduction toxicity study, and therefore the risk assessment is protective of these and other effects that occurred at higher doses; (6) the exposure databases (dietary food, drinking water, and residential) are complete; and (7) the risk assessment for each potential exposure scenario includes all metabolites and/or degradates of concern and does not underestimate potential exposure and risk for infants or children.

In the absence of the required inhalation toxicity study, HED is recommending the 10X FQPA factor be retained as a database uncertainty factor for assessing inhalation exposure and risk only, for both adults and children.

4.4.1	Completeness of the Toxicology Database

Acceptable guideline studies for developmental, reproductive toxicity and neurotoxicity (including DNT) are available for FQPA assessment.  Immunotoxicity studies in rats and mice have also been submitted and reviewed.  A subchronic inhalation study remains outstanding and is considered a data deficiency (TXR 0055320).

4.4.2	Evidence of Neurotoxicity

Neurotoxicity was observed in acute neurotoxicity studies in the rat and mouse.  Neurotoxicity was observed on the day of dosing and was not observed in subsequent evaluations.  In the rat, decreased arousal and motor activity were observed at the LOAEL of 100 mg/kg (NOAEL 60 mg/kg).  Effects at dose levels above the LOAEL in the rat study included tremors, slightly uncoordinated gait, effects on pupil response and righting reflex, and decreases in both temperature and ataxia.  In the mouse, transient signs of decreased spontaneous motor activity, tremors and deep respirations were observed at the LOAEL 50 mg/kg (NOAEL 25 mg/kg).  At higher dose levels, decreases in reactivity; grooming and muscle tone; prone position; staggered gait; mydriasis; and hypothermia were observed.  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.  Neurotoxicity was not observed in the subchronic neurotoxicity study with a high dose of 177/200 mg/kg/day (M/F) or any other study in the toxicity database.

4.4.3	Evidence of Sensitivity/Susceptibility in the Developing or Young Animal

There is no residual concern for increased qualitative or quantitative susceptibility in the rat or rabbit developmental toxicity studies.

In the two-generation reproduction developmental neurotoxicity studies in the rat, there was increased quantitative susceptibility as the offspring NOAELs were below the parental NOAELs.  However, clear NOAELs were identified for the offspring effects.

There were indications of potential immunotoxicity in the database.  Decreased absolute and relative thymus and spleen weights were observed in multiple studies.  Juvenile rats in the two-generation reproduction study appeared to be more susceptible to these effects, indicating a concern for qualitative susceptibility.  However, a guideline immunotoxicity study showed no evidence of clothianidin-mediated immunotoxicity in adult rats, and a developmental immunotoxicity study demonstrated no susceptibility with respect to immunotoxicity.  Therefore, the residual concern for immunotoxicity in adults and offspring is reduced.

Since there is evidence of increased quantitative susceptibility of the young following exposure to clothianidin in the rat reproduction study and the DNT study, HED performed a degree of concern analysis to: 1) determine the level of concern for the effects observed when considered in the context of all available toxicity data; and, 2) identify any residual uncertainties after establishing toxicity endpoints and traditional uncertainty factors to be used in the clothianidin risk assessment.  If residual uncertainties are identified, HED examines whether the residual uncertainties can be addressed by a FQPA safety factor, and if so, what factors should be retained.

Considering the overall toxicity profile and the endpoints and doses selected for the clothianidin risk assessment, HED characterized the degree of concern for the effects observed in the clothianidin 2-generation reproduction and DNT studies as low, noting that there are clear NOAELs for the offspring effects and regulatory doses were selected to be protective of these effects.  No other residual uncertainties were identified with respect to susceptibility.  HED believes that the endpoints and doses selected for clothianidin are protective of adverse effects in both offspring and adults.

4.4.4	Residual Uncertainty in the Exposure Database

In the absence of the 28-day inhalation study, there is uncertainty about potential portal of entry effects occurring via the inhalation route of exposure, and HED is recommending retaining the 10X FQPA factor as a database uncertainty factor for the inhalation route of exposure only, pending submission of the required study (Hazard and Science Policy Council, 23 March 2012, TXR# 0055320).

HED has used conservative assumptions in the dietary exposure assessment, including the use of 100% crop treated assumptions, tolerance-level residue values, and upper-bound estimates of potential exposure through drinking water.  In addition, the residential exposure assessment was conducted such that residential exposure and risk will not be underestimated.  The aggregate exposure and risk estimates presented in this assessment are expected to over-estimate actual exposure and risk expected based on the current and proposed use patterns, and no risk estimates of concern were identified.

4.5	Toxicity Endpoint and Point of Departure Selections

Based on the use pattern and the toxicological profile of clothianidin, HED selected endpoints and doses for acute and chronic dietary risk assessment and non-occupational and occupational exposures (i.e., incidental oral, dermal, or inhalation).  For occupational handlers and workers re-entering treated areas, HED selected endpoints and doses for dermal and inhalation exposure and risk assessment.

4.5.1	Endpoint Selection

The acute dietary endpoints and dose selected for risk assessment were based on single dose effects observed in the toxicity database; separate endpoints were selected for females 13-49 and the general US population including infants and children.  For all other exposure scenarios, including incidental oral, dermal and inhalation, HED relied on the endpoint and dose selected from the 2-generation reproduction toxicity study.  Because effects seen in the reproduction study can occur as the result of a single exposure at a critical junction during pregnancy or from multiple exposures throughout pregnancy and lactation, the NOAEL for offspring effects observed in the reproduction study was selected as the dose for all durations of exposure.  The dose selected for risk assessment is also the most sensitive for repeated exposures, and is protective of all other effects in the database.

Acute Dietary Endpoint for Females 13-49:  The endpoint used for establishing the aPAD for females 13-49 was selected from the developmental study in the rabbit.  An aPAD of 0.25 mg/kg/day was derived from a NOAEL of 25 mg/kg/day and a 100-fold factor that included 10x for inter-species extrapolations, 10x for intra-species variations, and a 1x FQPA SF.  The LOAEL of 75 mg/kg/day was based on increased litter incidence of a missing lobe of the lung.  This endpoint is appropriate for the acute dietary exposure assessment because it could be the result of a single exposure at a critical junction during pregnancy or from multiple exposures throughout pregnancy, it is an appropriate route of exposure (oral), and it is protective of developing offspring.

Acute Dietary Endpoint for the General Population:  The endpoint used for establishing the aPAD for the general population was selected from the acute neurotoxicity study in rats.  An aPAD of 0.25 mg/kg/day was derived from a NOAEL of 25 mg/kg/day and  a 100-fold factor that included 10x for inter-species extrapolations, 10x for intra-species variations, and a 1x FQPA SF.  The LOAEL of 50 mg/kg was based on transient signs of spontaneous motor activity, tremors, and deep respirations observed on Day 1.  Similar signs of neurotoxicity were observed in the acute neurotoxicity study in the rat at 100 mg/kg, with a NOAEL of 60 mg/kg.  This endpoint is appropriate for the acute dietary exposure assessment because it is the result of a single dose, is an appropriate route of exposure (oral) and is protective of the general population.  Although the developmental toxicity study in the rat had a lower maternal NOAEL of 10 mg/kg/day (LOAEL 40 mg/kg/day), this study was not chosen for endpoint selection because the NOAEL is considered to be artificially low due to dose spacing and because the effects (decreased body weight and food consumption) were not the result of acute exposure.

Chronic Dietary:  The endpoint used for establishing the cPAD was selected from the 2-generation reproduction study in the rat.  A cPAD of 0.01 mg/kg/day was derived from a NOAEL of 9.8 mg/kg/day and a 100-fold factor that included 10x for inter-species extrapolation, 10x for intra-species variability, and a 1x FQPA SF.  The LOAEL of 31.2 mg/kg was based on decreased body weight gains, delayed sexual maturation, decreased thymus weights in F1 pups, and increased stillbirths in both generations.  This study had the lowest NOAEL resulting from repeated dose exposure in the database.

Incidental Oral:  The endpoint used for assessing short-term incidental oral exposure was selected from the 2-generation reproduction study in the rat.  The NOAEL is 9.8 mg/kg/day, and the level of concern (LOC) is an MOE of 100 (10x for inter-species extrapolation, 10x for intra-species variability, and a 1x FQPA SF).  The effects observed at the LOAEL of 31.2 mg/kg have been described above (see chronic dietary).  The study, dose and endpoint were selected because of the exposure duration and because selection of the offspring effects is protective of the population of concern, developing children.

Dermal (All Durations):  The endpoint used for assessing all durations of dermal exposure was selected from the 2-generation reproduction study in the rat.  The NOAEL is 9.8 mg/kg/day, and the LOC is an MOE of 100 (10x for inter-species extrapolation, 10x for intra-species variability, and a 1x FQPA SF).  The effects observed at the LOAEL of 31.2 mg/kg have been described above (see chronic dietary).  The study was selected because of the exposure duration, and because it is protective of the population of the most sensitive population, developing children.  Although a dermal (route specific) toxicity study in rats was submitted, no effects were seen at the highest dose tested of 1000 mg/kg/day.  Use of the route-specific study for dermal risk assessment would not be protective of the offspring effects observed in both the DNT and the 2-generation reproduction studies because the dermal study does not evaluate reproduction and developmental parameters.  Since the dermal endpoint was selected from an oral study, a 1% dermal absorption factor (DAF) is used to determine dermal exposure and risk.

Inhalation (All Durations):  The endpoint used for assessing all durations of inhalation exposure was selected from the 2-generation reproduction study in the rat.  The NOAEL is 9.8 mg/kg/day, and the LOC is an MOE of 1000 (10x for inter-species extrapolation, 10x for intra-species variability, a 10x FQPA SF for residential scenarios, and a 10x database uncertainty factor for occupational scenarios).  The effects observed at the LOAEL of 31.2 mg/kg have been described above.  The study was selected because of the exposure duration, and because it is protective of the most sensitive population, developing children.  No route-specific information is available for the inhalation toxicity of clothianidin.  In the absence of a route-specific study, the NOAEL and LOAEL from an oral study have been used for risk assessment (i.e., inhalation toxicity is assumed to be equivalent to oral toxicity).

4.5.2	Recommendation for Combining Routes of Exposures for Risk Assessment

HED has chosen a single endpoint and dose from the 2-generation reproduction study for assessing exposure via incidental oral, dermal and inhalation routes.  Therefore, these routes of exposure can be combined in the risk assessment.

4.5.3	Cancer Classification and Risk Assessment Recommendation

Clothianidin is classified as "not likely to be carcinogenic to humans."  There was no treatment-related increase in tumor incidences in treated mice when compared to controls.  In the rat, there was an increase in thyroid c-cell tumors in female that did not appear to be significant, especially when carcinomas and adenomas are combined.  There was an increase incidence of hepatocellular carcinomas in male rats at the low and high doses just outside historical control incidences for the same testing laboratory (only 2 studies) but 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).  Clothianidin was positive for the gene mutation bacterial reverse mutation assay at the highest dose tested.  However, clothianidin and several metabolites were negative in the remaining mutagenicity studies.

4.5.4	Summary of Points of Departure and Toxicity Endpoints Used in Human Risk Assessment

Table 4.5.4a.  Summary of 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
Level of Concern (LOC) for Risk Assessment
Study and Toxicological Effects
Acute Dietary
Females age
13-49
NOAEL =
25 mg/kg/day
UFA = 10X
UFH = 10X
SFFQPA =1X

aRfD=0.25 mg/kg/day
aPAD=0.25 mg/kg/day
Rabbit developmental  study
LOAEL = 75 mg/kg/day based on increased litter incidence of a missing lobe of the lung
Acute Dietary
General population
NOAEL =
25 mg/kg/day
UFA = 10X
UFH = 10X
SFFQPA  = 1X
aRfD = 0.25
mg/kg/day

aPAD 0.25
mg/kg/day
Special neurotoxicity/pharmacology
study in mice
LOAEL = 50 mg/kg/day based on transient signs of decreased spontaneous motor activity, tremors and deep respirations
Chronic Dietary
All populations including infants and children
NOAEL=
9.8 mg/kg/day
UFA = 10X
UFH = 10X
SFFQPA =1X
cRfD=0.098 mg/kg/day

cPAD=0.098 mg/kg/day
2-Generation reproduction study
LOAEL = 31.2 mg/kg/day based on decreased body weight gains and delayed sexual maturation, decreased absolute thymus weights in F1 pups and increased stillbirths in both generations
Incidental Oral (short-term)
NOAEL=
9.8 mg/kg/day
UFA= 10X
UFH= 10X
SFFQPA=1X
MOE= 100 (residential)
2-Generation reproduction study
LOAEL= 31.2  mg/kg/day based on decreased body weight gains and delayed sexual maturation, decreased absolute thymus weights in F1 pups
Dermal (all durations)
Oral study NOAEL=
9.8 mg/kg/day
(dermal absorption = 1% of oral absorption)
UFA= 10X
UFH= 10X
SFFQPA=1X
MOE= 100 (residential)
2-Generation reproduction study
LOAEL = 31.2 mg/kg/day based on  decreased body weight gains and delayed sexual maturation, decreased absolute thymus weights in F1 pups and increased stillbirths in both generations
Inhalation (all durations)

Oral study NOAEL=
9.8 mg/kg/day
(inhalation toxicity = oral toxicity)
UFA= 10X
UFH= 10X
SFFQPA=10X for lack of subchronic inhalation study
MOE= 1000 (residential)
2-Generation reproduction study
LOAEL = 31.2 mg/kg/day based on decreased body weight gains and delayed sexual maturation, decreased absolute thymus weights in F1 pups and increased stillbirths in both generations

Cancer (oral, dermal, inhalation)
"Not Likely to be Carcinogenic to Humans"
Point of Departure (POD) = A data point or an estimated point that is derived from observed dose-response data and  used to mark the beginning of extrapolation to determine risk associated with lower environmentally relevant human exposures.  NOAEL = no observed adverse effect level.  LOAEL = lowest observed adverse effect level.  UF = uncertainty factor.  UFA = extrapolation from animal to human (interspecies).  UFH = potential variation in sensitivity among members of the human population (intraspecies).  UF DB = to account for the absence of key data.  SFFQPA = FQPA Safety Factor.  PAD = population adjusted dose (a = acute, c = chronic).  RfD = reference dose.  MOE = margin of exposure.  LOC = level of concern.  N/A = not applicable.

Table 4.5.4b.  Summary of Toxicological Doses and Endpoints for Clothianidin for Use in Occupational Human Health Risk Assessments.
Exposure/
Scenario
Point of Departure
Uncertainty/FQPA Safety Factors
Level of Concern (LOC) for Risk Assessment
Study and Toxicological Effects
Dermal (all durations) (Adults)
Oral study NOAEL=
9.8 mg/kg/day
(dermal absorption = 1% of oral absorption)
UFA= 10X
UFH= 10X

MOE= 100 (occupational)
2-Generation reproduction study
LOAEL = 31.2 mg/kg/day based on  decreased body weight gains and delayed sexual maturation, decreased absolute thymus weights in F1 pups and increased stillbirths in both generations
Inhalation (all durations)

Oral study NOAEL=
9.8 mg/kg/day
(inhalation toxicity = oral toxicity)
UFA= 10X
UFH= 10X
UFDB = 10X

MOE= 1000 (occupational)
2-Generation reproduction study
LOAEL = 31.2 mg/kg/day based on decreased body weight gains and delayed sexual maturation, decreased absolute thymus weights in F1 pups and increased stillbirths in both generations

Cancer (oral, dermal, inhalation)
"Not Likely to be Carcinogenic to Humans."
Point of Departure (POD) = A data point or an estimated point that is derived from observed dose-response data and  used to mark the beginning of extrapolation to determine risk associated with lower environmentally relevant human exposures.  NOAEL = no observed adverse effect level.  LOAEL = lowest observed adverse effect level.  UF = uncertainty factor.  UFA = extrapolation from animal to human (interspecies).  UFH = potential variation in sensitivity among members of the human population (intraspecies).  UF DB = to account for the absence of key data.  MOE = margin of exposure.  LOC = level of concern.  N/A = not applicable.

5.0	Dietary Exposure and Risk Assessment

5.1	Metabolite/Degradate Residue Profile
D262541, Y. Donovan, 2 February 2000

Previous risk assessments have described the available metabolism data to support use of clothianidin on a number of agricultural crops.  Appendix B summarizes the results of the available metabolism studies.  Based on these results, HED concluded that the nature of the residue has been adequately delineated, and that parent only is the residue of concern (ROC) to be used for the tolerance expression for primary crops and livestock commodities.  HED had previously determined that future new uses on root crops and/or leafy vegetables will require analysis for residues of the metabolite TMG along with parent in field trial samples, and that TMG should be included as a ROC for risk assessment if significant levels of TMG were observed.

Table 5.1.  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
Leafy and Root/Tuber Vegetables:  Parent + TMG
Other crops: Parent
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

5.2	Food Residue Profile
D397689, M. Doherty, 26 September 2012
D399953, M. Doherty, 26 September 2012

Adequate field trial data have been submitted to support the requested uses on strawberry, citrus, and tea, as well as the requested PHI reduction and tolerance increase for peppers and eggplant (Crop Subgroup 8-10B).  In addition, HED has adequate data to determine the potential for concentration of residues in citrus processed commodities; the data indicate concentration occurs only in dried citrus pulp.  Adequate data are available from representative tree nut commodities to translate the existing tolerance for residues in/on tree nuts to pistachio.  The data are summarized in the tables below.

Table 5.2.1.  Summary of Residue Data for Clothianidin in/on Bell and Non-Bell Peppers Following a 1-Day PHI.
Pepper Type
Variety
Trial Location
Application Rates, g a.i./A
Clothianidin Residues, ppm
Average Residue +- Std. Dev., ppm
Bell
Hunter
Tift, GA
44.54 + 45.16
0.085, 0.123
0.104 +- 0.027

Heritage
Barnwell, SC
45.42 + 45.30
0.068, 0.049
0.059 +- 0.013

Green Bell
Seminole, FL
45.05 + 44.75
0.094, 0.083
0.089 +- 0.008

Revolution
Martin County, FL
46.34 + 46.49
0.048, 0.034
0.041 +- 0.010

McCabi
Yuma, AZ
46.38 + 45.89
0.122, 0.127
0.125 +- 0.004

Cal Wonder
Tulare County, CA
45.21 + 46.30
0.198, 0.225
0.212 +- 0.019
Non-Bell
Mesilla
Seminole, FL
44.4 + 45.2
0.312, 0.282, 0.311
0.302 +- 0.017

Dulce
Yuma, AZ
46.9 + 47.3
0.069, 0.082, 0.114
0.088 +- 0.023

Conch
Tift, GA
45.4 + 45.1
0.019, 0.015, 0.021
0.018 +- 0.003

Summary of Clothianidin Residue Data for Strawberry, Citrus, and Tea.
Commodity
                          Application Rate, lb a.i./A
                                   PHI, days
                                       n
                               Clothianidin, ppm

                                     Min.
                                     Max.
                                     LAFT
                                     HAFT
                                    Median
                                     Mean
                                   Std. Dev.
Strawberry
                                      0.2
                                       1
10
0.096
1.170
0.103
1.120
0.258
0.327
0.301
Grapefruit
                                      0.2
                                       1
7
0.010
0.346
0.010
0.281
0.047
0.084
0.098
Lemon
                                      0.2
                                       1
7
0.022
0.201
0.034
0.176
0.094
0.105
0.050
Orange
                                      0.2
                                       1
13
0.005
0.269
0.008
0.219
0.057
0.083
0.066
Tea
                                  0.9  -  1.8
                                      3-7
12
2.14
38.0
2.15
37.55
13.95
15.21
11.76

Summary of Residues and Processing Factors from the Orange Processing Study.
Commodity
                           Residues (ppm) [Average]
                             Processing Factor[1]
Fruit
0.223
0.236 [0.242]
0.267
                                       _
Oil
< 0.005
< 0.005 [<0.005]
< 0.005
                                   <0.02
Juice
0.006
0.007 [0.006]
0.006
                                     0.03X
Dried Pulp
0.417
0.406 [0.406]
0.396
                                     1.68X
[1]Processing factor from RAC, calculated from the average residues.

5.3	Water Residue Profile

Based on available data, clothianidin is persistent under most field and laboratory conditions and is mobile to highly mobile based on laboratory adsorption tests.  The Environmental Fate and Effects Division (EFED) has supplied HED with Tier I estimated drinking water concentrations (EDWC) for clothianidin in surface water resulting from foliar application to rice (R. Baris, 15 September 2011, D393235).  EFED has confirmed that it is the appropriate value to use in this assessment (e-mail from R. Baris; 16 July 2012, 3:12:46 pm).

EFED used the Tier I Rice Model (v 1.0) as a screening model to calculate the surface water EDWC resulting from a single foliar application of clothianidin to a flooded field (as proposed on the label).  This concentration represents the estimated concentration that would be expected in the release water downstream of the treated rice paddy.  For the previous risk assessment in which HED also evaluated the use of clothianidin on leafy vegetables, the FIRST (FQPA Index Reservoir Screening Tool, version 1.1, 01/01/07) was used to calculate the surface water EDWC resulting from a single foliar application to leafy vegetables, as shown in the table below.  Potential residues in drinking water associated with the currently proposed uses would likely be much lower than those predicted using the Tier I Rice Model.

Table 5.3.  Tier I EDWCs for drinking water risk assessment based on the proposed clothianidin use on rice and leafy vegetables
Use (application rate, lbs a.i./A)
Model
                                     Acute
                                    Chronic
Surface water drinking water sources, downstream of rice paddy (0.084 lb a.i./A)
Tier I Rice Model (v1.0)
                                    72 ppb
                                  <72 ppb
Leafy vegetables (including brassica) (0.05 lb a.i./A)
FIRST
                                    4.0 ppb
                                    2.2 ppb

The EDWC of 72 ppb has been used to account for residues of clothianidin in both the acute and chronic dietary risk assessments.

5.4	Dietary Risk Assessment
D397690, M. Doherty, 26 September 2012

5.4.1	Description of Residue Data Used in Dietary Assessment

The acute and chronic assessments rely on tolerance-level residues (40 CFR 180.586) for all crops with registered and/or requested clothianidin uses.  For crops except leafy vegetables, the residue of concern for risk assessment purposes is the parent compound.  For root crops and leafy vegetables, the residues of concern are the parent compound and the TMG metabolite.  Field trial data show no detectable residues of TMG in root crops and that TMG does not exceed 10% of the parent compound residue level in leafy vegetables.  A factor of 1.1 (entered into the model as Adjustment Factor 1) has been incorporated into the assessment for leafy vegetables to account for the presence of TMG.  For livestock commodities, the residues of concern are the parent compound as well as the metabolites TZU, TZG, TZNG, ATMG-pyruvate, and ATG-acetate.  Milk is currently the only livestock-derived commodity with a tolerance for clothianidin.  A factor of 1.5, which is based on metabolism data, has been incorporated into the assessment to account for the residues of concern in milk.

There are a number of crops for which uses of both clothianidin and thiamethoxam have been registered.  The labels for the various end-use products containing these active ingredients prohibit the application of both active ingredients to the same crop during a growing cycle.  Due to that restriction and the assumption of 100% crop treated, a single value reflecting the greatest clothianidin residue from either active ingredient has been used for crops listed for use with both active ingredients (versus combined estimates from clothianidin and from thiamethoxam).  Generally, this assessment uses the established or recommended clothianidin tolerance for crops having tolerances for both compounds.  For foods with thiamethoxam tolerances but without clothianidin tolerances, maximum residues of clothianidin observed in thiamethoxam residue trials have been used in these assessments.  These include meats, meat by-products, artichoke, tropical fruits, coffee, hop, and mint (the estimate for residue in coffee was updated from 0.01 ppm to 0.04 ppm to reflect new data from recently submitted thiamethoxam field trials).

Orange processing study data show that clothianidin does not concentrate in citrus oil or juice.  Relative to the whole fruit, there is a modest increase in residues in pulp (1.8X).  These empirical processing factors, as well as those derived previously, have been included in these analyses.  Complete listings of the residue estimates, metabolite factors, and processing factors used in these analyses may be found in Attachment 1.

5.4.2	Percent Crop Treated Used in Dietary Assessment

HED assumed 100% crop treated for all food items in the dietary assessment for both acute and chronic exposure durations.

5.4.3	Acute and Chronic Dietary Risk Estimates

The acute and chronic assessments are based on highly conservative, health-protective assumptions regarding residue levels in food and percentage of crops treated.  Likewise, the estimated concentration in drinking water is highly conservative, especially given that it represents residues in rice paddy tail water and no adjustment was made to take into account the portion of the watershed that would be cropped to rice.  The analyses resulting from these assumptions should be considered screening-level analyses that likely overestimate actual dietary exposure to clothianidin.  All risk estimates (Table 5.4.4) are below HED's level of concern (<100% of the aPAD and cPAD).

 There are no dietary exposure or risk considerations that would preclude making the label amendment shortening the PHI for Crop Subgroup 8-10B, registering the clothianidin end-use products as requested, and establishing tolerances commensurate with those registration actions.

5.4.4	Dietary Exposure and Risk Estimate Summary Table

Table 5.4.4.  Summary of Acute and Chronic Dietary Exposure and Risk Estimates for Clothianidin.
Population Subgroup
                           Acute (95[th] Percentile)
                                    Chronic

                              Exposure, mg/kg/day
                                    % aPAD
                              Exposure, mg/kg/day
                                    % cPAD
                                      ARI
Total US Population
0.020913
8
0.007458
8
13.1
All Infants
0.051461
21
0.016683
17
5.87
Children 1-2 years old
0.069586
28
0.027256
28
3.60
Children 3-5 years old
0.048260
19
0.018444
19
5.31
Children 6-12 years old
0.024264
10
0.009165
9
10.7
Youth 13-19 years old
0.014341
6
0.005346
6
18.3
Adults 20-49 years old
0.015090
6
0.005822
6
16.8
Adults 50-99 years old
0.014403
6
0.006109
6
16.0
Female 13-49 years old
0.015390
6
0.005974
6
16.4
 The population subgroup(s) with the highest exposure/risk estimates are shown in bold.
[1]	ARI = Aggregate Risk Index.  ARI values <1 indicate a potential risk of concern.
ARI = NOAEL (9.8 mg/kg/day) / Exposure / LOC (Oral LOC = 100).

6.0	Residential (Non-Occupational) Exposure/Risk Characterization
D397691, S. Oonnithan, 27 September 2012

The use of clothianidin on turf, ornamental plants, and/or indoor surfaces may result in human exposure in a residential setting.  Such exposures may occur during application of products containing clothianidin (handler exposure) as well as following application (post-application exposure) and are expected to be of short-term (1-30 days) duration.  HED assessed exposure and developed risk estimates for numerous residential handler and post-application scenarios using the 2012 residential SOPs (M. Collantes, D397724, 15 August 2012).  Those assessments are based on conservative estimates of exposure and the results are summarized in Tables 4 and 5.

6.1	Residential Handler Exposure

For clothianidin, residential handler risk estimates are considered to be of potential concern when the dermal MOE is less than 100, the inhalation MOE is less than 1000, and/or the aggregate risk index (ARI), reflecting combined dermal and inhalation exposure, is less than one.  As shown in Table 6.1, the residential handler risk estimates are not of concern (ARIs range from 11 to 990).

Table 6.1.  Summary of Residential Handler Exposure and Risk Estimates for Clothianidin.  M. Collantes D397724, 15 August 2012.
Use Site
                              Application Method
                                  Formulation
                                   Activity
                              Exposure Estimate,
                                   mg/kg/day
                                     (MOE)
                                    ARI[1]

                                    Dermal
                                  Inhalation

Turf
Push-Type Spreader
                                  Arena 0.5G
                           Mixing/ Loading/ Applying
                                  2.3x10[-5]
                                   (420,000)
                                  7.5x10[-6]
                                  (1,300,000)
990
Turf
Belly Grinder
                                  Arena 0.5G
                               Loading/ Applying
                                  5.7x10[-4]
                                   (17,000)
                                  6.2x10[-6]
                                  (1,600,000)
160
Tree Trunk
Manually Pressurized Handwand
                                 Arena 50 WDG
                           Mixing/ Loading/ Applying
                                  6.8x10[-3]
                                    (1,400)
                                  2.0x10[-4]
                                   (50,000)
11
Lawns
Hose-End Sprayer
                                 Arena 50 WDG
                           Mixing/ Loading/ Applying
                                  3.8x10[-4]
                                   (25,000)
                                  6.4x10[-5]
                                   (150,000)
96
Fruit Trees
Hose-End Sprayer
                                 Arena 50 WDG
                           Mixing/ Loading/ Applying
                                 1.4 x 10[-3]
                                    (7,100)
                           3.3 x 10[-6] (2,900,000)
69
Indoor Surfaces (Bed Bug)
Manually Pressurized Handwand
                                  File Symbol
                                   73049-UIE
                           Mixing/ Loading/ Applying
                                  1.7x10[-4]
                                   (58,000)
                                  2.7x10[-4]
                                   (36,000)
34
Indoor Surfaces (Bed Bug)
Paintbrush
                                  File Symbol
                                   73049-UIE
                                   Applying
                                  1.1x10[-3]
                                    (9,000)
                                  4.9x10[-5]
                                   (200,000)
62
[1]	ARI is calculated as the NOAEL / Σ(Exposurei x LOC), where Exposurei is each exposure source being included in the ARI calculation and LOC is the product of the applicable safety factors (100 for dermal and oral exposures and 1000 for inhalation exposures).

6.2	Post-Application Exposure

There is potential for post-application dermal and inhalation exposure for adults and children resulting from use of clothianidin on residential turf, ornamentals (i.e., trees), and indoor surfaces.  There is also potential for incidental oral post-application exposure for children.  Table 6.2 provides a summary of the post-application exposure estimates and calculated ARIs.  As shown in Table 6.2, the residential post-application risk estimates are not of concern (ARIs range from 1.9 to 490).

Table 6.2.  Summary of Residential Post-Application Exposure and Risk Estimates for Clothianidin.  M. Collantes D397724, 15 August 2012.
Use Site
                                  Life Stage
                      Exposure Estimate, mg/kg/day (MOE)
                                    ARI[1]

                                 Hand-to-Mouth
                                Object-to-Mouth
                                Soil Ingestion
                                    Dermal
                                  Inhalation

Turf - WDG
                                     Adult
                                      NA
                                      NA
                                      NA
                                  1.7x10[-3]
                                    (5,600)
                                      NA

56

                              Child 1-2 years old
                                  6.2x10[-3]
                                    (1,600)
                                  1.9x10[-4]
                                   (52,000)
                                  1.4x10[-5]
                                   (720,000)
                                  2.9x10[-3]
                                    (3,300)

11
Pick-Your-Own Tree Crop  -  Apples and Pears
                                     Adult
                                      NA
                                      NA
                                      NA
                                    22,000
                                      NA
220

                               Child 6<11 yrs

                                    49,000

490

                              Child 1-2 years old

                                      NA

NA
Bed Bug  -  Carpet
                                     Adult
                                      NA
                                      NA
                                      NA
                                  3.9x10[-3]
                                    (2,500)
                                  7.1x10[-10]
                                 (1.4x10[10])
25

                              Child 1-2 years old
                                  4.9x10[-2]
                                     (200)
                                  7.0x10[-3]
                                    (1,500)
                                      NA
                                  3.3x10[-3]
                                    (3,000)
                                  2.5x10[-9]
                                  (3.9X10[9])
1.9
Bed Bug  -  Hard Surface
                                     Adult
                                      NA
                                      NA
                                      NA
                                  1.3x10[-3]
                                    (7,500)
                                  7.1x10[-10]
                                 (1.4x10[10])
75

                              Child 1-2 years old
                                  1.6x10[-2]
                                     (600)
                                  4.0x10[-3]
                                    (2,200)
                                      NA
                                  2.2x10[-3]
                                    (4,500)
                                  2.5x10[-9]
                                  (3.9X10[9])
5.4
Bed Bug  -  Mattress
                                     Adult
                                      NA
                                      NA
                                      NA
                                  6.9x10[-4]
                                   (14,000)
                                  7.1x10[-10]
                                 (1.4x10[10])
140

                              Child 1-2 years old
                                      NC
                                      NC
                                      NA
                                  1.6x10[-3]
                                    (6,200)
                                  2.5x10[-9]
                                  (3.9X10[9])
61
[1]	ARI values reflect combined oral, dermal, and inhalation exposure estimates identified by bold text; object-to-mouth and soil ingestion are not included due to the conservatism in the hand-to-mouth estimate.  ARI is calculated as the NOAEL / Σ(Exposurei x LOC), where Exposurei is each exposure source being included in the ARI calculation and LOC is the product of the applicable safety factors (100 for dermal and oral exposures and 1000 for inhalation exposures).
NA = Not Applicable.
NC = Not Calculated.  These exposure pathways are considered to be not relevant.  In the case of bed bug mattress treatments, the activities are expected to be much less frequent for sleeping children.  Exposures via these activities are addressed by hard surface and carpet scenarios.

6.3	Combined Exposure

HED combines risk estimates resulting from separate residential exposure scenarios when it is likely they can occur simultaneously based on the use-pattern and the behavior associated with the exposed life stage.  Although there is potential for adult exposure resulting from both applying the product and post-application activities, HED did not combine exposure estimates from adult handler and post-application activities because of the conservative assumptions and inputs within each exposure scenario.

Although Table 6.2 provides the estimates MOEs for object-to-mouth and soil ingestion, the combined children's exposure includes only the hand-to-mouth exposure for the incidental oral exposure component.  To include exposure from object-to-mouth and soil ingestion in addition to hand-to-mouth would overestimate incidental oral exposures for purposes of estimating combined residential exposure.

For purposes of performing an aggregate assessment, HED selected the worst-case adult and children exposure scenarios.  The treatment of tree trunks using a manually-pressurized handwand presents the worst-case exposure estimate for adults (ARI=11), while the bed bug scenario presents the worst-case exposure estimates for children 1 to < 2 yrs old (ARI=1.8).  A summary of the residential exposure scenarios for the aggregate assessment is provided in Table 6.3.

Table 6.3.  Residential Exposure Scenario and Risk Estimates for Aggregate Assessment.
Scenario
Life Stage
Scenario
                                Scenario ARI[1]
                                Combined ARI[2]
                               Handler Scenarios
Tree Trunk
Adult
Manually Pressurized Handwand
11
11
Lawns
Adult
Hose-End Sprayer
96
40
Fruit Trees
Adult
Hose-End Sprayer
69

                          Post-Application Scenarios
Bed Bug
Adult
Perimeter (Carpet)
25
21

Mattress
140

Children 1 to < 2 years old
Perimeter (Carpet)
1.9
1.8

Mattress
61

[1]	Scenario ARIs are from Tables 4 and 5 for handler and post-application exposures, respectively.
[2]	Combined ARI = 1/Σ(1/ARIScenario), where ARIScenario is the ARI for each scenario being included in the combined ARI.

6.4	Residential Bystander Post-Application Inhalation Exposure

Based on the Agency's current practices, a quantitative post-application inhalation exposure assessment was not performed for clothianidin at this time primarily because of the low acute inhalation toxicity (Toxicity Category IV), low vapor pressure (1.3x10[-10]Pa, 9.75x10[-13] mmHg), and the low proposed use rate (not to exceed 0.2 lb a.i./A/season).  However, volatilization of pesticides may be a source of post-application inhalation exposure to individuals nearby pesticide applications.  The Agency sought expert advice and input on issues related to volatilization of pesticides from its Federal Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel (SAP) in December 2009, and received the SAP's final report on March 2, 2010 (http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html).  The Agency is in the process of evaluating the SAP report and may, as appropriate, develop policies and procedures to identify the need for and, subsequently, the way to incorporate post-application inhalation exposure into the Agency's risk assessments.  If new policies or procedures are developed, the Agency may revisit the need for a quantitative post-application inhalation exposure assessment for clothianidin.

Although a quantitative bystander risk assessment was not conducted, post-application inhalation assessments were conducted to evaluate uses of clothianidin within a residential dwelling and risk estimates were not of concern.  It is anticipated that these exposures are greater than those that would occur for residential bystanders and are, therefore, protective of bystander exposures that may occur.

6.5	Spray Drift

Spray drift is always 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 (see the Agency's Spray Drift website for more information at http://www.epa.gov/opp00001/factsheets/spraydrift.htm).  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 with specific products with significant risks associated with drift.

Although a quantitative residential post-application inhalation exposure assessment was not performed as a result of pesticide drift from neighboring treated agricultural fields, an assessment for clothianidin was performed for inhalation exposure to flaggers and the risk was not of concern (ARI = 27, Table 9.1).  This exposure scenario is representative of a worse case inhalation (drift) exposure and may be considered protective of most outdoor agricultural and commercial post-application inhalation exposure scenarios.

7.0	Aggregate Exposure/Risk Characterization

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

7.1	Acute Aggregate Risk

Typically, HED does not consider residential exposures when assessing acute aggregate risk unless such exposures can be characterized as a series of single-day exposures, which is not the case for clothianidin.  Therefore, acute aggregate risk estimates for clothianidin are equivalent to the acute dietary risk estimates (Section 5.4) and are below HED's level of concern.  There are no acute aggregate risk issues that would preclude granting the actions requested by the registrant.

7.2	Short- and Intermediate-Term Aggregate Risk

In estimating aggregate risk, HED has considered the combined residential ARIs (Table 6.3) and the dietary exposure ARIs in Table 5.4.4.  The aggregate ARIs (Table 7.2) are the worst-case risk estimates for each life stage.  The aggregate ARIs are all greater than 1 and indicate that aggregate risks are not of concern.

Table 7.2.  Aggregate Risk Estimates for Clothianidin.
Life Stage
Residential Combined ARI[1]
                                Dietary ARI[1]
                               Aggregate ARI[2]
Adult
11
16.0
6.5
Children 1 to < 2 years old
1.8
3.60
1.2
[1]	Residential Combined ARIs are the minimum ARI for each life stage from Table 6.3; Dietary ARIs are from Table 5.4.4.  The adult dietary ARI is from the population subgroup Adults 50-99 years old and is the most conservative ARI from any of the adult-only subgroups.
[2]	Aggregate ARI = 1/(1/ARIResidential + 1/ARIDietary)

7.3	Chronic Aggregate Risk

Chronic aggregate risk assessments address exposures that are likely to occur, continuously, for greater than six months.  In the case of clothianidin, residential exposures are not expected to occur on a chronic basis; therefore, the chronic aggregate risk estimates are equivalent to the dietary risk estimates (Section 5.4.3) and are below HED's level of concern.  There are no chronic aggregate risk issues that would preclude granting the actions requested by the registrant.

7.4	Cancer Aggregate Risk

Clothianidin is classified as "Not Likely to be Carcinogenic to Humans;" therefore, cancer risk is not a concern.

8.0	Cumulative Exposure/Risk Characterization

Clothianidin is a member of the neonicotinoid class of pesticides and is a major metabolite of another neonicotinoid, thiamethoxam.  Structural similarities or common effects do not constitute a common mechanism of toxicity.  Evidence is needed to establish that the chemicals operate by the same, or essentially the same, sequence of major biochemical events (EPA, 2002).  Although clothianidin and thiamethoxam bind selectively to insect nicotinic acetylcholine receptors (nAChR), the specific binding site(s)/receptor(s) for clothianidin, thiamethoxam and the other neonicotinoids are unknown at this time.  Additionally, the commonality of the binding activity itself is uncertain, as preliminary evidence suggests that clothianidin operates by direct competitive inhibition, while thiamethoxam is a non-competitive inhibitor.  Furthermore, even if future research shows that neonicotinoids share a common binding activity to a specific site on insect nAChRs, there is not necessarily a relationship between this pesticidal action and a mechanism of toxicity in mammals.  Structural variations between the insect and mammalian nAChRs produce quantitative differences in the binding affinity of the neonicotinoids towards these receptors which, in turn, confers the notably greater selective toxicity of this class towards insects, including aphids and leafhoppers, compared to mammals.  While the insecticidal action of the neonicotinoids is neurotoxic, the most sensitive regulatory endpoint for clothianidin is based on unrelated effects in mammals, including changes in body and thymus weights, delays in sexual maturation, and still births.  Additionally, the most sensitive toxicological effect in mammals differs across the neonicotinoids (such as testicular tubular atrophy with thiamethoxam, and mineralized particles in thyroid colloid with imidacloprid).  Thus, there is currently no evidence to indicate that neonicotinoids share common mechanisms of toxicity, and EPA is not following a cumulative risk approach based on a common mechanism of toxicity for the neonicotinoids.  For information regarding EPA's efforts to determine which chemicals have a common mechanism of toxicity, and to evaluate the cumulative effects of such chemicals, see the policy statements concerning common mechanism determinations, and procedures for cumulating effects from substances found to have a common mechanism, released by OPP on EPA's website at http://www.epa.gov/pesticides/cumulative/.

9.0	Occupational Exposure/Risk Characterization
D397691, S. Oonnithan, 27 September 2012

9.1	Short- and Intermediate-Term Handler Risk

HED has assumed that both short- and intermediate-term occupational exposures may occur.  Short-term exposures (1-30 days) are likely to occur for many occupational exposure scenarios.  Certain application scenarios (e.g., aerial application) are likely to be conducted by contract applicators whose exposure may extend into an intermediate-term (1-6 months) duration.

Chemical-specific data for estimating occupational exposure to clothianidin were not submitted.  It is the policy of HED to use the best available data to assess handler exposure.  Sources of generic handler data, used as surrogate data in the absence of chemical-specific data, include the Pesticide Handlers Exposure Database Version 1.1 (PHED 1.1), the Agricultural Handler Exposure Task Force (AHETF) database, or other registrant-submitted occupational exposure studies.  Some of these data are proprietary (e.g., AHETF data), and subject to the data protection provisions of FIFRA.  The standard values recommended for use in predicting handler exposure that are used in this assessment, known as "unit exposures", are outlined in the "Occupational Pesticide Handler Unit Exposure Surrogate Reference Table" (http://www.epa.gov/opp00001/science/handler-exposure-table.pdf), which, along with additional information on HED policy on use of surrogate data, including descriptions of the various sources, can be found at http://www.epa.gov/pesticides/science/handler-exposure-data.html.

Dermal and inhalation exposures were calculated for various levels of personal protective equipment (PPE).  Results are presented for "baseline," defined as a single layer of clothing consisting of a long sleeved shirt, long pants, shoes plus socks, no protective gloves, and no respirator, as well as baseline with various levels of PPE as necessary (e.g., gloves, respirator, etc).  The product labels for Arena[(R)] 50 WDG and V-10170 2.13 SC recommend applicators and other handlers must wear long-sleeved shirt and long pants, shoes plus socks and chemical-resistant gloves made of any waterproof material.

Occupational handler exposure and risk estimates are summarized in Table 9.1.  Since the short- and intermediate-term endpoints and PODs are the same for each route of exposure, only short-term exposures were estimated, and are considered protective of intermediate-term exposure and risk.  Estimated exposure and risk associated with the new foliar and/or soil treatments on citrus fruit trees, pistachio, and strawberry resulted in ARIs of 1.1 to 660 for mixers/loaders, applicators, and flaggers, assuming baseline PPE plus gloves, engineering controls such as enclosed cockpit, and open cabs.  These estimated risks are not of concern.  For aerial uses of Arena[(R)] 50 WDG and V-10170 2.13 C formulations, the estimated ARIs for mixers/loaders, applicators, and flaggers ranged from 1.1 to 260, assuming use of baseline clothing plus gloves and an enclosed cockpit (engineering controls) for aerial applications.

Table 9.1.  Summary of Occupational Handler Exposure and Risk Estimates for Clothianidin.
Scenario
Crop
                            Dermal Dose, mg/kg/day
                          Inhalation Dose, mg/kg/day
                                 Dermal MOE 1
                               Inhalation MOE 2
                                Combined ARI 3
                                 Mixer/Loader
Arena WDG, Aerial
Strawberry
0.00052
0.00909
18721
1078
1.1
Arena WDG, Groundboom
Strawberry
0.00012
0.00208
81904
4717
5
V-10170 2.13 SC, Aerial
Strawberry, Citrus, Pistachio
0.00019
0.00011
51383
88219
75
V-10170 2.13 SC, Ground boom
Strawberry
0.00004
0.00003
224801
385959
330
V-10170 2.13 SC, Air blast
Citrus
0.00002
0.00001
449601
77918
660
                                  Applicator
Arena WDG, Aerial
Strawberry
0.00005
0.00007
193200
142059
130
Arena WDG, Groundboom
Strawberry
0.00004
0.00008
262500
124301
110
V-10170 2.13 SC, Aerial
Strawberry, Citrus, Pistachio
0.00003
0.00003
386400
284118
260
V-10170 2.13 SC, Ground boom
Strawberry
0.00002
0.00004
525000
248603
240
V-10170 2.13 SC, Air blast
Citrus, Nectarine, Pistachio
0.00092
0.00027
10632
35382
27
                                    Flagger
V-10170 2.1 SC & Arena WDG
All crops
0.00012
0.00036
80500
27600
27
                            Mixer/Loader/Applicator
V-10170 2.1 SC & Arena WDG , Soil broadcast, Backpack
Strawberry, Citrus; dilution =0.02 lb a.i./gal
0.00096
0.00003
10223
327616
78
V-10170 2.1 SC & Arena WDG , Soil drench, MPHG
Strawberry, Citrus; dilution = 0.004 lb a.i./gal
0.000226
0.000226
43000
43000
39
1 Dermal MOE = NOAEL (9.8 mg/kg/day) / Dermal Exposure.
2 Inhalation MOE = NOAEL (9.8 mg/kg./day) / Inhalation Exposure.
3 ARI (Aggregate Risk Index) = 1 / [(1/ Dermal MOE) + (1/ Inhalation MOE)]

9.2	Short- and Intermediate-Term Post-Application Risk

9.2.1	Dermal Post-Application Risk

Chemical-specific dislodgeable foliar residue data have not been submitted for clothianidin.  Therefore, this assessment uses HED's default assumption that 25% of the application is available for transfer on day 0 following the application and the residues dissipate at a rate of 10% each following day.

It is the policy of HED to use the best available data to assess post-application exposure.  Sources of generic post-application data, used as surrogate data in the absence of chemical-specific data, are derived from ARTF exposure monitoring studies, and, as proprietary data, are subject to the data protection provisions of FIFRA.  The standard values recommended for use in predicting post-application exposure that are used in this assessment, known as "transfer coefficients", are presented in the ExpoSAC Policy 3 which, along with additional information about the ARTF data, can be found at the Agency website.

The post-application dermal exposures and risks resulting from foliar applications of clothianidin on citrus fruit, nectarine, pistachio, and strawberry are summarized in Table 9.2.1.  The short- and intermediate-term post-application dermal MOEs ranged from 8,400 to 22,000 are not of concern at the LOC of >=100.  The post-application dermal exposures resulting from soil-directed applications of clothianidin on citrus and strawberry and trunk treatment on citrus were not assessed as there are no surrogate transfer coefficients available for broadcast, band, in-furrow, soil drench, or tree trunk applications.  However, dermal post-application exposures for workers from such treatments are expected to be minimal because workers do not come in contact with the treated surfaces.  Therefore, post-application risks for these uses are not of concern.

Table 9.2.1.  Post-application Dermal Exposures and Risks Resulting from Foliar Use of Clothianidin on Citrus, Nectarine, Pistachio, and Strawberry.
                                     Crop
                                  Activities
                                  Appl. Rate
                                   (lb ai/A)
                                 Estimated DFR
                                (ug/cm[2]) [1]
                                   Transfer
                           Coefficient (cm[2]/hr) [2]
                                    Dermal
                              Dose 3 (mg/kg/day)
                           Short-term Dermal MOE [4]
Citrus fruits
Fruit harvesting
                                      0.1
                                     0.280
                                     1,400
0.000454
22,000
Nectarine
Thinning of fruits

                                     3,600
0.00117
8,400
Pistachio
Harvesting

                                     1,400
0.000454
22,000
Strawberry
Harvesting, training
                                      0.2
                                     0.561
                                     1,100
0.000715
14,000
1.  Dislodgeable Foliar Residue (DFR) = Application Rate (lb ai/A) * (1- Daily Dissipation Rate)[t] * Conv. Factor(4.54E+8 ug/lb) * Conv. Factor (2.47E-8 A/cm[2])* Residue Transfer Rate (20% default) after treatment.
2.  Transfer coefficient (TC) from ExpoSAC Policy #3, June 3, 2011.
3.  Dermal Dose (mg/kg/day) = [DFR * TC * Conv. Factor (0.001 mg/ug) * Dermal Absorption Factor (1%) * 8 hrs/day] / Body Weight (69 kg).
4.  MOE= Short-term Dermal NOAEL (9.8 mg/kg/day) / Dermal Dose (mg/kg/day).

9.2.2	Inhalation Post-Application Risk

Based on the Agency's current practices, a quantitative post-application inhalation exposure assessment was not performed for clothianidin at this time primarily because of the low acute inhalation toxicity (Toxicity Category IV), low vapor pressure (1.3x10[-10] Pa, 9.75x10[-13] mm Hg) and low application rates (0.2 lb ai/A).  However, there are multiple potential sources of post-application inhalation exposure to individuals performing post-application activities in previously treated fields.  These sources include volatilization of pesticides and resuspension of dusts and/or particulates that contain pesticides.  The Agency sought expert advice and input on issues related to volatilization of pesticides from its FIFRA Scientific Advisory Panel (SAP) in December 2009, and received the SAP's final report on March 2, 2010 (http://www.epa.gov/ scipoly/SAP/meetings/ 2009/120109meeting.html).  The Agency is in the process of evaluating the SAP report as well as available post-application inhalation exposure data generated by the ARTF and may, as appropriate, develop policies and procedures, to identify the need for and, subsequently, the way to incorporate occupational post-application inhalation exposure into the Agency's risk assessments.  If new policies or procedures are put into place, the Agency may revisit the need for a quantitative occupational post-application inhalation exposure assessment for clothianidin.

Although a quantitative post-application inhalation exposure assessment was not performed for clothianidin, HED has assessed inhalation exposure and risk for occupational flaggers resulting from aerial applications and the risk was not of concern (ARI = 27, Table 9.1).  Inhalation exposure for flaggers is likely to result in higher exposure than that from post-application activities performed in the treated field.  Therefore, it is expected that the flagger inhalation exposure estimates would be protective of most occupational post-application inhalation exposure scenarios.

10.0	References

D397689.	M. Doherty. 26 September 2012. Clothianidin  -  New Uses on Strawberry, Pistachio, Citrus, and Tea.  Evaluation of Residue Chemistry Data.

D397690.	M. Doherty. 26 September 2012. Clothianidin  -  Acute and Chronic Dietary Exposure and Risk Estimates for Requested Amended Registration on Peppers and New Uses on Strawberry, Citrus, Pistachio, and Tea.

D397691.	S. Oonnithan. 27 September 2012. Clothianidin.  Occupational Exposure Assessment for New Uses on Citrus, Nectarine, Pistachio, and Strawberry; and Label Amendments to Add Aerial Application.

D399953.	M. Doherty. 26 September 2012. Clothianidin  -  Proposed Label Amendments: Reduction in PHI for Crop Subgroup 8-10B (Peppers and Eggplant) and Change in Tolerance.

D397724.	M. Collantes.  15 August 2012.  Clothianidin:  Occupational and Residential Exposure and Risk Assessment to Support the Proposed Bed Bug Treatment.

TXR# 0055320.  J. Van Alstine.  23 March 2012.  Clothianidin:  Summary of Hazard and Science Policy Council (HASPOC) Meeting of March 8, 2012:  Recommendation on the need for a 28-day inhalation study.

Appendix A.  Toxicology Profile and Executive Summaries

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    21- or 28-Day Inhalation
                                      yes
                                      yes
                                      yes
                                      no
                                    yes[a]
                                      yes
                                      yes
                                      yes
                                       -
                                      no
870.3700a  Developmental Toxicity (rodent)
870.3700b  Developmental Toxicity (nonrodent)
870.3800    Reproduction
                                      yes
                                      yes
                                      yes
                                      yes
                                      yes
                                      yes
870.4100a  Chronic Toxicity (rodent)
870.4100b  Chronic Toxicity (nonrodent)
870.4200a  Oncogenicity (rat)
870.4200b  Oncogenicity (mouse)
870.4300    Chronic/Oncogenicity
                                      yes
                                      yes
                                      yes
                                      yes
                                      yes
                                      yes
                                      yes
                                      yes
                                      yes
                                      yes
870.5100    Mutagenicity -- Gene Mutation - bacterial
870.5300    Mutagenicity -- Gene Mutation - mammalian
870.5xxx    Mutagenicity -- Structural Chromosomal Aberrations
870.5xxx    Mutagenicity -- Other Genotoxic Effects
                                      yes
                                      yes
                                      yes
                                      yes
                                      yes
                                      yes
                                      yes
                                      yes
870.6100a  Acute Delayed Neurotox. (hen)
870.6100b  90-Day Neurotoxicity (hen)
870.6200a  Acute Neurotox. Screening Battery (rat)
870.6200b  90-Day Neuro. Screening Battery (rat)
870.6300    Develop. Neuro
                                      no
                                      no
                                      yes
                                      yes
                                      yes
                                       -
                                       -
                                      yes
                                      yes
                                      yes
870.7485    General Metabolism
870.7600    Dermal Penetration
870.7800    Immunotoxicity..............................................................
                                      yes
                                      yes
                                      yes
                                      yes
                                      yes
                                      yes
Special Studies
         Developmental Immunotoxicity

                                      yes

                                      yes
[a] The subchronic inhalation study is required.  HED has recommended that this study be called in to support registration review.

A.2.  Toxicity Profiles

Table A.2.1.  Acute Toxicity Profile - Clothianidin Technical, Intermediates, and Metabolites.
                                 Test Material
                                 Guideline No.
                                  Study Type
                                    MRID(s)
                                    Results
                               Toxicity Category
Technical
870.1100
Acute oral - rat
                                   45422621
LD50 > 5000 mg/kg
                                      IV
BN0230M  Metabolite
870.1100
Acute oral - rat
                                   45422628
LD50 > 2000 mg/kg (♂+♀)
                                      III
BN0335E2 Metabolite
870.1100
Acute oral - rat
                                   45422623
LD50 > 2000 mg/kg (♂+♀)
                                      III
MAI
Metabolite
870.1100
Acute oral - rat
                                   45422629
LD50 = 758 mg/kg (♀)
Males not more susceptible
                                      III
Clothianidin-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. = 384-561)
LD50 = 425 mg/kg (♂+♀;
95% C.I. = 380-475)
                                      II
Technical
870.1200
Acute dermal - rat
                                   45422634
LD50 > 2000 mg/kg
                                      III
Technical
870.1300
Acute inhalation
                                   45422636
LC50 > 5.538 mg/L (♂+♀)
                                      IV
Technical
870.2400
Acute eye irritation
                                   45422701
Slightly irritating to the eye
                                      IV
Clothianidin-CCMT- Adduct Intermediate
870.2400
Acute eye irritation
                                   45422814
Not irritating to the eye
                                      IV
Clothianidin-Triazan Intermediate
870.2400
Acute eye irritation
                                   45422819
Not irritating to the eye
                                      IV
Technical
870.2500
Acute dermal irritation
                                   45422703
Not irritating to the skin
                                      IV
Clothianidin-CCMT- Adduct Intermediate
870.2500
Acute dermal irritation
                                   45422813
Not irritating to the skin
                                      IV
Clothianidin-Triazan Intermediate
870.2500
Acute dermal irritation
                                   45422820
Not irritating to the skin
                                      IV
Technical
870.2600
Skin sensitization
                                   45422705
Is not a sensitizer under conditions of study
                                      N/A
Clothianidin-CCMT- Adduct Intermediate
870.2600
Skin sensitization
                                   45422815
Is not a sensitizer under conditions of study
                                      N/A
Clothianidin-Triazan Intermediate
870.2600
Skin sensitization
                                   45422821
Is a sensitizer under conditions of study
                                      N/A

Table A.2.2.	  Subchronic, Chronic and Other Toxicity Profile for Clothianidin.
                                  Guide line
                                  Study Title
                                     MRID
                                    Results
870.3100
90-Day Oral Toxicity - rat (diet)
45422809
(2000)
45422708
(4-week)
Acceptable/
guideline
ppm=0, 150, 500  & 3000
mg/kg/day (M/F)=0/0, 9.0/10.9, 27.9/34.0, 202.0/254.2
NOAEL = 27.9/34.0 mg/kg/day (M/F)
LOAEL = 202.0/254.2 mg/kg/day (M/F)
based on decreased BW and BW gain.
870.3150
13-Week Oral Toxicity- dog (diet)
45422810
2000
45422808
2000
4-week
45422811
1998
palatability
Acceptable/
guideline
ppm=0, 325, 650, 1500 & 2250
mg/kg/day
(M/F)=0/0, 9.2/9.6, 19.3/21.2, 40.9/42.1, 58.2/61.8
NOAEL = 19.3/42.1 mg/kg/day (M/F)
LOAEL = 40.9/61.8 mg/kg/day (M/F) based on thinness, decreased body weight, body weight gain and anemia (1 M); and on decreased white blood cells, albumin, and total protein (F).
870.3200
28-Day Dermal Toxicity - rat
45422707 (2000)
Acceptable/
guideline
mg/kg/day= 0, 100, 300 & 1000
NOAEL = 1000 mg/kg/day (HDT)
LOAEL = Not established
870.3700a
Developmental Toxicity- rat (gavage)
45422711 (1998)
45422710 (1998)
range-finding
Acceptable/
guideline
mg/kg/day=0, 10, 40 & 125
Maternal NOAEL = 10 mg/kg/day
Maternal LOAEL = 40 mg/kg/day based on decreased body weight gain and food consumption.
Developmental NOAEL = 125 mg/kg/day (HDT)
Developmental LOAEL = Not established
870.3700b
Developmental Toxicity- rabbit (gavage)
45422713 (1998)
45422712 (1998)
range-finding
Acceptable/
guideline
mg/kg/day=0, 10, 25, 75 & 100
Maternal NOAEL = 25 mg/kg/day
Maternal LOAEL = 75 mg/kg/day based on increased incidences of clinical signs (scant feces and orange urine), mortalities, decreased food consumption, early delivery, abortion, and decreased body weight gain.
Developmental NOAEL = 25 mg/kg/day
Developmental LOAEL = 75 mg/kg/day based on premature deliveries, decreased gravid uterine weights, an increased litter incidence of a missing lobe of the lung, and decreased litter average for ossified sternal centra per fetus.
870.3800
Reproduction (2- Generation)- rat (diet)
45422715 (2000)
45422714 (2000)
pilot
45422716
(2001)
supplemental
45422825 (1999)
rat feed
45422826
(1999)
rat feed
Acceptable/
guideline
ppm=0, 150, 500 & 2500
mg/kg/day
(M/F)=0/0, 9.8/10.7, 31.2/34.3,163.4/188.8
Parental/Systemic NOAEL = 31.2/36.8 mg/kg/day (M/F)
Parental/Systemic LOAEL = 163.4/188.8 mg/kg/day (M/F) based on decreased body weight, body weight gain, and absolute and relative thymus weights.
Reproductive NOAEL = 31.2/188.8 mg/kg/day (M/F)
Reproductive LOAEL = 163.4/not established mg/kg/day (M/F) based on decreased sperm motility and increased number of sperm with detached heads in both generations.
Offspring NOAEL = 9.8/11.5 mg/kg/day (M/F)
Offspring LOAEL = 31.2/36.8 mg/kg/day (M/F) based on decreased body weight gains and delayed sexual maturation (M), decreased absolute thymus weights in F1 pups of both sexes, and an increase in stillbirths in both generations.
870.4100
Chronic (1 year) - dog (diet)
45422717 (2000)
45422718
Acceptable/
guideline
ppm=0, 325, 650, 1500 & 2000
mg/kg/day (M/F)=0/0,  4.8/8.5, 16.6/15.0, 36.3/40.1, 46.4/52.9
NOAEL = 46.4/40.1 mg/kg/day (M/F)
LOAEL = not established/52.9 mg/kg/day (M/F) based on clinical evidence of anemia in females.
Note:  dose-related decreases in ALT activity observed in mid- and high-dose males and females.
870.4200
Carcinogenicity, 18-Month - mouse (diet)
45422721 (2000)
45422709
(1997)
4-week
45422722
(2001)
supplementary
Acceptable/
guideline
ppm=0,100, 350 or 1250
mg/kg/day
(M/F)=0/0, 13.5/17.0, 47.2/65.1, 171.4/215.9
In addition: 50/sex - 700 ppm (wk 1-4), 2000 (5-10), 2500 (11-34), 2000/1800 (M/F) 35-79 [254,1/322,3]
NOAEL = 171.4/65.1 mg/kg/day (M/F)
LOAEL = 254.1/215.9 mg/kg/day (M/F) based on decreased body weight and body weight gain; decreased food consumption and food efficiency in males at the LOAEL.
No evidence of carcinogenicity.
870.4300
Chronic/ Carcinogenicity, 2-Year-rat (diet)
45422719 (2000)
45422720
(2001)
supplementary
Acceptable/
guideline
ppm (M/F)=0,  150, 500, 1500 & 3000
mg/kg/day
(M/F)=0/0, 8.1/9.7, 27.4/32.5, 82.0/97.8, 156.5/193.4
NOAEL = 82.0/32.5 mg/kg/day (M/F)
LOAEL = 156.5/97.8 mg/kg/day (M/F) based on decreased body weight and food consumption and altered hepatocellular eosinophilic focus of the liver in both sexes; ovary interstitial gland hyperplasia and increased lymphohistiocytic infiltrate in females; and slightly increased incidences of pelvic mineralization and transitional cell hyperplasia in the kidney, mottled livers of males.
No evidence of carcinogenicity.
870.5100

Gene Mutation bacterial reverse mutation assay
Parent
45422731 (2000)
Acceptable/
guideline
Small, but significant increase in frequency of histidine revertants in TA 1535 strain treated at 1500 and 5000 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
45422732
(1990)
Acceptable/
guideline
No mutagenic activity in bacteria (S. typhimurium and E. coli) under conditions of this assay.
870.5100
Gene Mutation bacterial reverse mutation assay
Parent
45422733
(1999)
Acceptable/
guideline
No mutagenic activity in bacteria (S. typhimurium) under conditions of this assay.
870.5100
Gene Mutation bacterial reverse mutation assay
Parent
45422734
(1999)
Acceptable/
non-guideline
(only TA 1535 assayed)
Only TA 1535 tested. No mutagenic activity in bacteria (S. typhimurium) under conditions of this assay.
870.5100
Gene Mutation bacterial reverse mutation assay
BN0335E2 metabolite
45422724
(2000)
Acceptable/
guideline
No mutagenic activity in bacteria (S. typhimurium) under conditions of this assay.
870.5100
Gene Mutation bacterial reverse mutation assay
TZMU metabolite
45422725
(1999)
Acceptable/
guideline
No mutagenic activity in bacteria (S. typhimurium) under conditions of this assay.
870.5100
Gene Mutation bacterial reverse mutation assay
methyl guanidine intermediate
45422726
(1999)
Acceptable/
guideline
No mutagenic activity in bacteria (S. typhimurium) under conditions of this assay.
870.5100
Gene Mutation bacterial reverse mutation assay
TZNG metabolite
45422727
(1999)
Acceptable/
guideline
No mutagenic activity in bacteria (S. typhimurium) under conditions of this assay.
870.5100
Gene Mutation bacterial reverse mutation assay
TMG metabolite
45422728
(1999)
Acceptable/
guideline
No mutagenic activity in bacteria (S. typhimurium) under conditions of this assay.
870.5100
Gene Mutation bacterial reverse mutation assay
BN0230M metabolite
45422729
(2000)
Acceptable/
guideline
No mutagenic activity in bacteria (S. typhimurium) under conditions of this assay.
870.5100
Gene Mutation bacterial reverse mutation assay
MAI metabolite
45422730
(1999)
Acceptable/
guideline
No mutagenic activity in bacteria (S. typhimurium) under conditions of this assay.
870.5100
Gene Mutation bacterial
reverse mutation assay
N=Methylnitroguanidin intermediate
45422812
(2001)
Acceptable/
guideline
No mutagenic activity in bacteria (S. typhimurium) under conditions of this assay.
870.5100
Gene Mutation bacterial reverse mutation assay
TI 435-Triazan intermediate
45422822
(2000)
Acceptable/
guideline
No mutagenic activity in bacteria (S. typhimurium) under conditions of this assay.
870.5100
Gene Mutation bacterial reverse mutation assay
TI 435-CCMT-Adduct
45422816
(2000)
Acceptable/
guideline
No mutagenic activity in bacteria (S. typhimurium) under conditions of this assay.
870.5300
Gene Mutation - in vitro mammalian cell gene mutation test (L5178Y TK +/- mouse lymphoma cells)
45422737 (2000)
Acceptable/
guideline
Increases in mutant frequency with and without S9 at dose levels that were cytotoxic.  The observed response was primarily due to small colony formation, indicating clastogenic activity.
870.5300
Gene Mutation - in vitro mammalian cell gene mutation test (V79-HPRT Assay)
45422738
(1999)
Acceptable/
guideline
No increase in mutant frequency under the conditions of the study.
870.5300
Gene Mutation  -  in vitro mammalian cell gene mutation test (V79 - HPRT Assay)
46339001
(2003)
Acceptable/
guideline
There was no evidence of induced mutant colonies over background.
870.5375
Cytogenetics - in vitro mammalian chromosome aberration test (CHL Cells)
Parent
45422736
(2000)
Acceptable/
guideline
Significant increases in frequency of cells with structural aberrations.  Predominant types were chromatid breaks and exchanges.  There was, however, no clear indication of a dose-related response in either the presence or absence of S9 activation.
870.5375
Cytogenetics  -  in vitro mammalian chromosome aberration test (CHL Cells)
Parent
46339002
(2003)
Acceptable/
guideline
Clothianidin was clastogenic in the absence of S9 activation but only at precipitating concentrations.  Some doubt regarding the relevance of this finding since clastogenicity was abolished when exogenous metabolic activation was incorporated into the test system and was confined to precipitating concentrations.
870.5395
Cytogenitics - mammalian erythrocyte micronucleus test
Parent
45422740
(2000)
Acceptable/
guideline
Clothianidin is considered to be neither clastogenic nor aneugenic under these test conditions.
870.5395
Cytogenetics - mammalian erythrocyte micronucleus test
Parent
46339003
(2003)
Acceptable/
guideline
No significant increase in the frequency of MPCEs in bone marrow after any harvest in the test groups up to an overtly toxic dose for this test system.
870.5550
Other Effects - DNA Repair Test in B. subtilis
Parent
45722735
(1990)
Unacceptable/
non-guideline (only single plates used)
No potential for DNA damage under these conditions.
870.5500
Other Effects - (UDS) in Mammalian Cells in Culture
Parent
45422739
(1999)
Acceptable/
non-guideline
(only males used)
No evidence (or a dose related positive response) that UDS was induced.
870.6200a

Acute Neurotoxicity Screening Battery-rat (gavage)
45422801
 (2000)
45422802
(2000)
to establish NOEL
Acceptable/
guideline
mg/kg=0,100, 200 & 400
NOEL=0, 20, 40 & 60
NOAEL = 60 mg/kg
LOAEL = 100 mg/kg based on FOB findings (decreased arousal, motor activity, and locomotor activity).
870.6200b

Subchronic Neurotoxicity Study-rat (diet)
45422803 (2000)
45422825
(1999)
supplementary
Acceptable/
guideline
ppm (M/F)=0, 150, 1000 & 3000
mg/kg/day
(M/F)=0/0,9.2/10.6, 60.0/71.0, 177.0/200.1
NOAEL = 60.0/71.0 mg/kg/day (M/F)
LOAEL = 177.0/200.1 mg/kg/day (M/F) based on slightly decreased food consumption, body weights, and body weight gains.

No evidence of neurotoxicity.
870.6300

Developmental Neurotoxicity Study-rat
(diet)
445422804
(2000)
Acceptable/
non-guideline
(upgradable with FOB information)
ppm=0, 150, 500 & 1750
mg/kg/day
gestation=0, 12.9, 42.9, 142
lactation=0, 27.3, 90.0, 299.0
Maternal NOAEL = 42.9 mg/kg/day
Maternal LOAEL = 142 mg/kg/day based on decreased body weights, body weight gains, and food consumption.
Offspring NOAEL = 12.9 mg/kg/day
Offspring LOAEL = 42.9 mg/kg/day based on decreased body weights, body weight gains, motor activity, and acoustic startle response in females.
870.7485
Metabolism Study- rat

45422805 (2000)
45422806
 (2000)
Acceptable/
guideline
single dose=2.5 or 250mg/kg;
14-day repeated dose =25 mg/kg/day
Overall recovery: 95-100%. Readily absorbed and excreted within 96 hours following a single 2.5 mg/kg bw or repeated oral dose of 25 mg/kg bw, but at a dose of 250 mg/kg, absorption became biphasic and was saturated.  Following single or multiple oral low doses (2.5 and 25mg/kg bw, respectively) of clothianidin, urinary excretion accounted for 89.2-94.6% of the administered radioactivity suggesting that a multiple exposure regimen did not affect the absorption/excretion processes.  Urinary excretion unaffected following single 250 mg/kg dose.  Excretion via the feces accounted for the remainder of the administered radioactivity in all treatment groups (3.8-8.6%). Rapid absorption and distribution of administered radioactivity to all organs and tissues followed by rapid excretion with reduction to background levels in most tissues and organs within 24 hours. Somewhat greater rate of absorption and elimination in females.  Excretory patterns did not exhibit gender-related variability but reflected the delayed absorption in the high-dose group.  Neither clothianidin nor metabolites appear to undergo significant sequestration.
 The metabolites identified (primarily oxidative demethylation products and cleavage products of the nitrogen-carbon bond between the nitroimino and thiazolyl moieties) were consistent with Phase I processes.  Extraction efficiencies appeared to be excellent and most components in all of the matrices examined (urine, feces, and tissues) were adequately quantified and characterized.  The available data, based upon studies using both the nitroimino- and the thiazolyl-2-labeled clothianidin, affirmed the metabolism pathway proposed by the investigators.
870.7485
Metabolism Study  -  mice

45422807
(2000)
Acceptable/
non-guideline
single gavage dose of 5 mg/kg
Of the administered radioactivity, 98.7-99.2% was recovered. Readily absorbed and excreted within 168 hours following a single oral dose of 5 mg/kg body weight.  Urine was the major route of excretion, accounting for 92.4-93.7% of the administered radioactivity. Feces accounted for 5.0-6.8% of the administered radioactivity.  Within 24 hours, 89.0-91.7 % of the administered radioactivity was excreted in the urine and 4.9-6.2% was excreted in the feces.  Residual radioactivity in any given tissue at 168 hours post-dose was considerably less than 1% of the administered dose.  Therefore, neither clothianidin nor its metabolites appeared to exhibit potential for bioaccumulation. Excretory patterns did not exhibit gender-related variability.
Both urinary and fecal metabolites were identified using TLC and radioautography in conjunction with known standards and were quantified by TLC/LSC .  The major metabolites in both urine and feces were the parent compound (clothianidin) and TZNG [N-(2-chlorothiazol-5-ylmethyl)-N-nitroguanidine] which resulted from 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
45868001 (2003)
Acceptable/
non-guideline
6.13 ug/cm2
8 hour exposure
Undiluted FS 600 formulation of clothianidin (10% ai)

Dermal absorption as the sum of urinary and fecal excretion and Cage/Pan/Chair Wash, Debris was 0.24 (+ 0.11) as percent of dose. Adjustment of the direct absorption determination was not necessary because recovery from the dermal dose was >90%.
A value of 1% dermal absorption was considered appropriate for use in risk assessment.  This estimation takes into account any variability that would have likely occurred with testing several dose levels.
870.7800
Immunotoxicity - rat (adult) (diet)
46536502
(2004)
Acceptable/
guideline
ppm=0, 150, 500 & 3000
mg/kg/day
(M/F)=0/0, 13.8/14.0, 45.8/46.2, 252.8/253
Immunotoxicity NOAEL = 253 mg/kg/day (M&F)

Immunotoxicity LOAEL = not established

At the highest dose tested, 253 mg/kg/day, a decrease in body weights, body weight gains and food consumption were noted in adult males and females.
Non-guideline
Developmental Immunotoxicity study - rat
(diet)
47526501 (2008)
Acceptable/
non-guideline
ppm=0, 150, 500 & 2000
mg/kg/day
gestation=0, 10, 35, 121
lactation=0, 22, 68, 250
after weaning:
Assay 1=0/0, 28/26, 98/93,404/404
Assay 2=0/0, 28/27, 89/93, 338/398
No immunotoxicological adverse effects at any of the doses tested.
Non-guideline
Other Genotoxicity  -  Unscheduled DNA synthesis in primary rat hepatocytes
46339004
(2003)
Acceptable/
non-guideline
No evidence of DNA damage and repair in this test system, as determined by radioactive tracer procedures (nuclear silver grain counts).
Non-guideline
Special Study:
Neurotoxicity and pharmacology - mouse
45422823
(2000)
Acceptable/
non-guideline
mg/kg=0, 12.5, 25, 50, 100, 200, 400 (single gavage dose)
NOAEL = 25 mg/kg/day (M/F)
LOAEL = 50 mg/kg (M/F) based on transient signs of decreased spontaneous motor activity, tremors and deep respirations.

A.3.  Endpoint Selection

Acute Reference Dose (aRfD) - General Population

Studies Selected:  Special Neurotoxicity/Pharmacology study in Mice (MRID 45422823)

Dose and Endpoint for Risk Assessment: NOAEL = 25 mg/kg/day (both studies) based on transient signs of spontaneous motor activity, tremors, and deep respirations observed on Day 1 at 50 mg/kg/day.

Comments about Study/Endpoint/Uncertainty Factors:  These endpoints and dose were selected because the oral route of exposure is relevant to dietary risk assessment and the duration of exposure is relevant to acute dietary risk.  Similar signs of neurotoxicity were observed in the acute neurotoxicity study in the rat at 100 mg/kg, with a NOAEL of 60 mg/kg.  Although the developmental toxicity study in the rat had a lower maternal NOAEL of 10 mg/kg/day (LOAEL 40 mg/kg/day), this study was not chosen for endpoint selection because the NOAEL is considered to be artificially low due to dose spacing.  The standard uncertainty factors (100x) were applied to all dietary exposure scenarios (10x for intraspecies variability and 10x for interspecies extrapolation).

Acute Reference Dose (aRfD)  -  Females 13-49

Studies Selected:  Developmental Study in the Rabbit (MRID 45422713, 45422712)

Dose and Endpoint for Risk Assessment: NOAEL = 25 mg/kg/day (both studies) based on increased litter incidences of a missing lobe of the lung observed on Day 1 at 75 mg/kg/day.

Comments about Study/Endpoint/Uncertainty Factors:  The endpoint and dose were selected because:  1) the oral route of exposure is relevant to dietary risk assessment, 2) the duration of exposure is relevant to acute dietary risk and 3) they are protective of potential offspring effects.  Based on the available data, HED determined that changes in organ development can occur as the result of a single exposure at a critical junction during pregnancy or from multiple exposures throughout pregnancy and lactation.  The standard uncertainty factors (100x) were applied to all dietary exposure scenarios (10x for intraspecies variability and 10x for interspecies extrapolation).

Chronic Reference Dose (cRfD)

Studies Selected:  2-Generation Reproduction Study in the Rat (MRID 45422715, 45422714)

Dose and Endpoint for Risk Assessment: NOAEL = 9.8 mg/kg/day based on decreased body weights gains, delayed sexual maturation, decreased thymus weights in F1 pups, and increased stillbirths in both generations at the LOAEL of 31.2 mg/kg/day.

Comments about Study/Endpoint/Uncertainty Factors:  This endpoint and dose was selected because: 1) the oral route of exposure is relevant to dietary risk assessment, 2) the duration of exposure is relevant to chronic risk scenarios, and 3) it is the lowest endpoint in the toxicology database and is therefore protective of both chronic effects and potential qualitative sensitivity of offspring.  The standard uncertainty factors were applied to all dietary exposure scenarios (10x for intraspecies variability and 10x for interspecies extrapolation).

Incidental Oral Exposure

Short- and Intermediate-Term Incidental Exposure (1-30 days and 1-6 months)

Studies Selected:  2-Generation Reproduction Study in the Rat (MRID 45422715, 45422714)

Dose and Endpoint for Risk Assessment: NOAEL = 9.8 mg/kg/day based on decreased body weights gains,, delayed sexual maturation, decreased thymus weights in F1 pups, and increased stillbirths in both generations at the LOAEL of 31.2 mg/kg/day.

Comments about Study/Endpoint/Uncertainty Factors:  The NOAEL and LOAEL from the 2-generation reproduction study were selected for the short- and intermediate-term incidental oral risk assessment because they are protective of developmental effects present in rat pups observed in the presence of less severe maternal effects at similar doses.  The standard uncertainty factors (100x) were applied (10x for intraspecies variability and 10x for interspecies extrapolation).

Dermal Exposure

All Durations

Studies Selected:  2-Generation Reproduction Study in the Rat (MRID 45422715, 45422714)

Dose and Endpoint for Risk Assessment: NOAEL = 9.8 mg/kg/day based on decreased body weights gains, delayed sexual maturation, decreased thymus weights in F1 pups, and increased stillbirths in both generations at the LOAEL of 31.2 mg/kg/day.