UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

~ I 

I 

MEMORANDUM 

Subject : Registration Review - Preliminary Problem Formulation for the Ecologic 

Assessment of Clethodim 

To: Susan Lewis, Chief 

Reregistration Branch 1 

Special Review and Reregistration Division 

Office of Pesticide Programs 

From: Ron Dean, Biologist 

Jonathan Angier, Environmental S 

Environmental Risk Branch 2 

Environmental Fate and Effects Division -0i - 

Office of Pesticide Programs i 

Through: Tom Bailey, Branch Chief 

Environmental Risk Branch 2 

Environmental Fate and Effects Division 

Office of Pesticide Programs i 

Attached is the preliminary problem formulation for the ecological risk assessment to be 

conducted as part of the registration review of the herbicide clethodim. 

TEXT SEARCHABLE DOCUMENT
ECOLOGICAL RISK ASSESSMENT 

PROBLEM FORMULATION FOR: 

Ron Dean, Biologist 

Jonathan Angier, Environmental Scientist 

Environmental Risk Branch 2 

Environmental Fate and Effects Division 

Office of Pesticide Programs 

Tom Bailey, Chief 

Environmental Risk Branch 2 

Environmental Fate and Effects Division 

Off ice of Pesticide Programs 
STRESSOR SOURCE AND DISTRIBUTION ............................................................................ INTEGRATION OF AVAILABLE INFORMATION ................................................................... ECOLOGICAL EFFECTS ........................................................................................................ Toxicity Studies .................................................................................................... EXPOSURE CHARACTERISTICS ........................................................................................... CHARACTERISTICS OF ECOSYSTEMS POTENTIALLY ATRISK ............................................. CONCEPTUAL MODEL ........................................................................................................ ANALYSIS PLAN OPTIONS ................................................................................................. ANTICIPATED DATA NEEDS ........................................................................................... LITERATURE CITED ............................................................................................................ 

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STRESSOR SOURCE AND DISTRIBUTION 

Clethodim is currently registered for use as a post-emergence selective herbicide against 

a wide range of annual and perennial grasses (monocotyledon plant species) in a 

variety of broad leaf crops including soybeans, cotton, flax, peanuts, sunflowers, s gar 

beets, potatoes, alfalfa and vegetables. It is a member of the cyclohexenone or ":"' 

cyclohexanedione class of herbicides. The mode of action for this herbicide is lipi 

biosynthesis inhibition. Sensitivity or selectivity of grasses has been demonstrate to be 

due to a greater susceptibility at the acetyl-CoA carboxylase (ACCase) enzyme of ass 

species. These grass species are killed by the inhibition of the ACCase enzyme, w ich is 

a key enzyme in the lipid biosynthetic pathway. Clethodim is typically applied as 

irrigation systems). 

spray, aerial spray, as spot treatment by hand spray, or by chemigation (via sprinkl r 

loud 

I 

The most recent risk assessments available in the docket which serve as the basis f r this 

problem formulation include the following: P 

Use on Field Corn completed on October 1,2007 (DP Barcode: 333334) 1 

Use on Asparagus, Herbs, Hops, Leafy Greens, Safflower, Sesame, and Su 

Beans and Peas completed on January 3 1,2007 (DP Barcode: 3 13467) 

The ecological risk assessment for the use on field corn found that clethodim pose risks 

above the Agency's Level of Concern (LOC) of 1.0 to listed and non-listed monoc t 

terrestial plant species inhabiting semiaquatic areas that receive drainage fiom us sites 

(RQ = 3.13). Clethodim does not exceed the Agency's LOC for direct toxic effect to 

birds, mammals, freshwater invertebrates, freshwater fish, aquatic dicot plants, or lgae 

for this use. No data were available to evaluate potential risks to estuarinelrnarine 

acute estuarinelmarine invertebrate data by which to perform th~s analysis. 

organisms or to assess chronic risks to freshwater fish. Approaches for extrapolati I g 

chronic toxicity values fiom existing data were explored but none were found to b 

appropriate. An acute to chronic ratio cannot be employed to estimate these values due to 

the fact that there are no chronic aquatic invertebrate data, acute estuarinelmarine sh ! or 

~ 

Based on the ecological risk assessment for uses on flax, leafy greens, sesame, safflower, 

herbs, hops, asparagus, and legumes, clethodim was predicted to pose risks above 

Agency's LOC to listed and non-listed monocot terrestrial plant species inhabiting pland 

areas adjacent to clethodim use sites as well as semiaquatic areas that receive drain ge 

from clethodim use sites. Risk quotients which exceed the Agency's LOC for mon cot 

species were 2.3 1 for non-listed and 3.8 for listed species inhabiting upland areas 1 

adjacent to clethodim applications, and 16.67 for non listed and 26.25 for listed spe 

semi aquatic areas exposed to clethodim runoff. Clethodim was not found to 
Toxicity Studies 

Agency's LOC for birds, mammals, fieshwater invertebrates, freshwater fish, aqutic 

plants, and algae for these uses. However, no data were available to evaluate potebtial 

risks to estuarinelrnarine organisms or to assess chronic risks to fieshwater fish. ! 

Approaches for extrapolating chronic toxicity values from existing data were not 1 

Acute and chronic toxicity data from studies submitted by pesticide registrants 

the available open literature are used to evaluate the potential direct er'fects of 

to the aquatic and terrestrial receptors identified in this section. This includes 

data on the technical grade active ingredient, degradates, and when available, 

products (e.g. "Six-Pack" studies). ' The open literature studies are identified 

EPA7s ECOTOX database (http://c~ub.eva.aov/ecotox/), which employs a litera 

search engine for locating chemical toxicity data for aquatic life, terrestrial 

wildlife. The evaluation of both sources of data can also provide insight 

and indirect effects of clethodim on biotic communities fiom loss of 

sensitive to the chemical and from changes in structure and 

the affected communities. 

appropriate due to lack of chronic aquatic invertebrate, acute estuarinelmarine fish 

acute estuarinelmarine invertebrate data. 

Clethodirn and its metabolites containing the 5-(2-ethylthiopropyl)cyclohexene-3-dne and 

5-(2-ethylthiopropy1)-5-hydroxycyclohexene-3-one moieties and their sulfoxides 

sulfones are all expressed as clethodim and will be modeled as total residues. Tab e 1 

provides a summary of the taxonomic groups and the surrogate species tested to h lp 

understand potential acute ecological effects of pesticides to these non-target taxo omic 

groups. In addition, this table provides a preliminary overview of the potential ac e 

toxicity of clethodim by providing the acute toxicity classifications. r i 

and 
Table 1. Test Species Evaluated for Assessing Potential Ecological Effects of Clethodim and 

Associated Acute Animal Toxicity Classification 

Taxonomic Group ( Example(s) of Surrogate Species I Acute Toxicity CIassification 

I I 

Bobwhite Quail (Colinus virginianus) Practically Non-Toxic MRID 409745-26 

Bobwhite Quail (Colinus virginianus) 

MRID 409745-25 Practically Non-Toxic 

Mammals 

the 

Insects 

Laboratory rat (Rattus novvegicus) 

MRID 409745-07 Slightly Toxic 

Honey bee (Apis rnellifea) 

MRID 410302-05 

Freshwater fish2 

~reshwiter fish may be surrogates for aiuatic-ph&e amphibians.& 

Practically Non-Toxic 

Freshwater invertebrates 

Monocot plants are of special concern due to the fact that clethodim is an 

mode of action specific to them. Clethodim is slightly toxic to 

moderately toxic to freshwater invertebrates. There are no data to evaluate acute 

chronic effects to estuarinelmarine fish and estuarinelmarine 

endpoint values are summarized in Table 2. Assessment endpoints for Clethodi 

Rainbow trout (Oncorhynchus mykiss) 

MRID 409745-28 

I 1. Abundance (i.e., ( la. Acute I Bobwhite quail I Single oral 1 >2000 ( 409745-25 I 

slightly ~~~i~ 

Birds represent surrogates for terrestrial-phase amvhibians and reutiles. 

Water flea (Daphnia magna) 

MRID 416851-01 

survival, reproduction, and (Dose 

growth) of individual birds based) 

Moderately Toxic 

2. Abundance (i.e., 

survival, reproduction, and 

growth) of individual 

mammal 

(Dietarybased) 

Chronic 

(Dietarybased) 

r Chronic 

(Colinus dose 

virginianus) 

(Colinus 

virginianus) 

Bobwhite quail Avian 250 ppm 410302-06 * 

(Colinus reproduction (NOAEC) (Supple iental) 

virginianus) study 

I I I I 

Rat (Rattus I Single oral ( 1,360 mg ( 409745-47 

nomegicus) dose 

I 

Rat (Rattus 2-Generation 500 ppm a.i 

norvegicus) reproduction (NOAEC) 
reproduction of iYeshwater 

fish and invertebrates 

populations of non-target 

terrestrial plants (crops 

and non-crop plant 
(Selenastmm 

capricomutum) 

Freshwater diatom 

(Navicula 

pelliculosa) - H (NOAEC) 

6d. Algae 

adequately explained. 

I 

Incident Reports 

Marine alga 

(Skeletonema 

costatum) 

I I (NOAEC) I 

Incident # 1002969-058 

In 1995 the use of Select 2EC (a.i. Clethodim) allegedly caused damage to 

after direct application in Florida. The certainty that clethodim caused this 

was "possible"; however the legality of this applicatiofi is undetermined. 

only incident reported involving clethodim. 

Important physical/chemical properties of clethodim are listed in Table 3. 

120 hours 

* The study is classified as supplemental because it was determined to be scientifically sound but does not fulfill 

requirements for an avian reproductive test, since a high rate of adult mortality in both control and test subjects 

Table 3 Nature of the Chemical Stressor I 

i 

the 

was not 

8.6 mg 

a.i./L (EC,) 

5.4 mg 

a.i./L 

Persistence: With a soil aerobic half-life of <3 days and an aerobic aquatic ha1 -life of 

5 days, clethodim is fairly non-persistent under aerobic conditions. However, t is 

much more persistent in anaerobic conditions; half-life in anaerobic waterlsedipent i 

Common name 

Chemical name 

Pesticide type 

Chemical class 

CAS number 

Empirical formula 

Molecular mass (glmol) 

Vapor pressure 

Henry's Law Constant 

(atm-m3/mol) 

Solubility in water (mg/L) 

pKa 

420297 

Accept 

Clethohm 

(E, E)-(~)-2-[1-[[(3-chloro-2-propenyl)oxy]imino]propyl]-5-[~2- 

(ethy1thio)propyll-3-hydroxy-2-cyclohexen- 1 -one 

herbicide 

cyclohexenone or cyclohexanedione 

99129-21-2 

c17H26c1N03s 

359.9 

4.2 mPa at 20 OC 

1.2~1 0-l1 atm-m3/mol 

5400 at pH 7 (solubility is highly pH dependent) 

4.47 

04 

'ble 

Log Kow 4.2 
systems was 177 days (at 25OC). Two toxic degradates of concern, clethodim I 

sulfoxide and clethodim sulfone, are much more persistent than parent, with s 

aerobic half-lives of -35 days. Both parent clethodim and degradates of conc 

(sulfoxide & sulfone) are mobile, with Koc values ranging from 5-270 ml/g 

Mobile" to "Moderately Mobile" according to FA0 classification scheme). 1 

The major degradation pathway for clethodim is microbial in addition to phot 

Clethodim is essentially stable to hydrolysis and photolysis is dependant upon 

exposure to direct sunlight (although photolysis may be a significant 

mechanism for foliar applications in bright sunlight, as 

occurs too rapidly to establish a half-life). Aqueous 

ranged fi-om 1.4 days (at pH 5) to 9.3 days (at pH 9) 

pH 7 were approximately 4-6 days. 

The main routes of dissipation in the environment are likely to be microbial 

degradation, leaching and runoff. Volatilization is not expected to be an imp0 ant 

dissipation pathway. 1 

The major degradates of clethodim that qualify as degradates of concern are 

clethodim sulfoxide and clethodim sulfone (Federal Register / Vol. 62, No. 29 

February 12, 1997). Both of these toxic degradates are more mobile and persi tent 

than the parent, so are more likely to present risk in aquatic and terrestrial 

environments. 

1 I 

No surface water monitoring data for clethodim or its major degradates were 

the literature or the U.S. Geological Survey NAWQA database. 

Clean Water Act: 1 

Clethodim is not identified as a cause of impairment for any water bodies listed as ~ 

impaired under section 303(d) of the Clean Water Act, based on information pro~ired at: 

http://oaspub.epa.gov/Wwaters~~ist.impaiments?pimpid=3. The Agency invi es 

submission of water quality data for this pesticide. To the extent possible, data sh X uld 

conform to the quality standards in Appendix A of the OPP Standard Operating ~ 

Procedure: Inclusion of Impaired Water Body and Other Water Quality Data in O~P'S 

Registration Review Risk Assessment and Management Process (see: 

ht.tp://www.epa.gov/oppfeadl/cb/ppdc/2006/novemberO6/sessionl -sop.pdf), in 

ensure they can be used quantitatively or qualitatively in pesticide risk 

Clethodim is currently registered for use on a variety of crops. A map of 

the US is represented in Figure 1. This map is based on 2002 data and is 

map available. New uses on Asparagus, Corn, Herbs, Hops, Leafy 

Sesame, Succulent Beans and Peas have been registered since this 
In 2008, estimated annual agricultural use was roughly 424,500 pounds of 

applied in the United States. The majority is applied to Soybeans 

Beets (80,000 lbs), Sunflowers (40,000 lbs), Alfalfa (30,000), and 

(20,000 lbs each). Screening level estimates of agricultural uses of clethodim are ~ 

described in Table 4. 1 

Figure 1. 2002 Estimated Annual Agricultural Use Map for clethodim (Sourc 

USGS). 

CLETHODIM - herbicide 

2002 estimated annual agriculhual use 

Average annual use of 

actve ingredient (pomds per square mile of aglcultural land in county) - k.! noestimated use 

o.oo1 to 0.008 

0.- to 0.038 

0.039 to 0.132 

0.133 to 0.322 

1 >=0.323 

1 miion 

alfalfa hav 

Total 

Dounds awM 
Screening Level Estimates of Agricultural Uses of Clethodirn 

January 28,2008 

Screening Level Estimates ofAgricultura1 Uses of CLETHODIM 121011 

Sorted Alphabetically 

Crop 

Alfalfa 

Almonds 

Apples 

Asparagus 

Barley + 

Beans, Green 

Beets ( NPUD '02 ) 

Broccoli 

Brussels Sprouts * 

Cabbage 

CanolaIRapeseed 

Cantaloupes 

Carrots 

Celery 

Cherries 

Corn 

Cotton 

Cucumbers 

Dry Beandpeas 

Garlic 

Lettuce 

Mint ( NPUD '02 ) 

Nectarines * + 

Olives * 

Onions 

Oranges + 

Peanuts 

Peas, Green 

peppers 

Pistachios * 

Potatoes 

Pumpkins 

Sod ( NPUD '02 ) + 

Sorghum 

Soybeans 

Squash 

Strawbemes 

Sugar Beets 

Sunflowa 

Sweet Corn 

Sweet Potatoes ( NPUD '02 ) 

Tomatoes 

Walnuts 

Lbs. A.I. 

All numbers rounded. 

'1500' indicates less than 500 pounds of active ingredient. 

'<2.5' indicates less than 2.5 percent of crop is treated. 

'4' indicates less than 1 percent of crop is treated. 

* CA data only, but 95% or more of U.S. acres are in California 

Percent Crop Ttd. 

Avg. Max. 

<I <2.5 

<1 <2.5 

<1 c2.5 

5 10 

<1 <2.5 

<I 5 

N/C <1 

10 10 

N/C NIC 

<1 <2.5 

5 5 

<1 5 

15 35 

5 5 

<1 <2.5 

<1 <2.5 

<I <2.5 

<1 12.5 

5 5 

5 5 

<1 <2.5 

NIC 5 

N/C N/C 

N/C N/C 

15 30 

<1 c2.5 

10 10 

<1 c2.5 

5 10 

NIC NIC 

<l 5 

10 20 

N/C <1 

<1 (2.5 

5 5 

5 5 

5 5 

45 45 

20 25 

<1 <2.5 

N/C <1 

il 5 

<1 12.5 

SLUA data sources include: 

USDA-NASS (United States Department of Agriculture's National Agricultulal Statistics Service); 

2001-2006 

Private Pesticide Market Research, 2001-2006 

NPUD 2002 (National Pesticide Use Database) of the CropLife Anerica Foundation and California 

DPR data. 

These results reflect amalgamated data developed by the Agency and are releasable to the public. 

NIC = Not calculated 

+ = These crops were not listed as active product regismtiom when this report was run 
Assessment endpoints are defined as "explicit expressions of the actual environmjntal 

value that is to be protected." Defining an assessment endpoint involves two st 

identifying the valued attributes of the environment that are considered to be at 

2) operationally defining the assessment endpoint in terms of an ecological enti 

community of fish and aquatic invertebrates) and its attributes (i.e., survival and 

reproduction). Therefore, selection of the assessment endpoints is based on value 

entities (i.e., ecological receptors), the ecosystems potentially at risk, the migatio 

pathways of pesticides, and the routes by which ecological receptors are expos 

pesticide-related contamination. The selection of clearly defined assessment 

important because they provide direction and boundaries in the risk assessment fo 

addressing risk management issues of concern. Changes to assessment endpoints 

typically estimated from the available toxicity studies, which are used as the 

effects to characterize potential ecological risks associated with exposure to 

such as clethodim. 

To estimate exposure concentrations, the ecological risk assessment considers 

at the maximum rate to fields that have vulnerable soils. If multiple applications 

allowed, the maximum amount per application and minimum interval between 

applications are used - provided that maximum total annual application 

included in this configuration. Several EFED exposure models (e.g., 

EXAMS, T-REX) are used to estimate likely high-end exposure to 

sensitive toxicity endpoints are used from surrogate test species to 

related direct effects on acute mortality and chronic reproductive, 

assessment endpoints. Toxicity tests are intended to determine 

exposure on birds, mammals, fish, 

tests include short-term acute, sub-acute, and 

arranged in a hierarchical or tiered system 

applied field studies. The toxicity studies 

to cause adverse effects, to determine whether further testing is required, and to 

determine the need for precautionary label 

effects to non-target animals and plants. 

In order for a chemical to pose an ecological risk, it must reach ecological 

pesticide moves in the environment from a source to an ecological receptor. For 

biologically significant concentrations. An exposure pathway is the means by 

ecological exposure pathway to be complete, it must have a source, a release 

an environmental transport medium, a point of exposure for ecological receptors, 

feasible route of exposure. 

The conceptual model (Figure 2) depicts the potential pathways for ecological risk 

associated with clethodim use. The conceptual model provides an overview of the 
expected exposure routes for organisms within the clethodim action area. For tenestrial 

organisms, the major route of exposure (aside fiom direct contact to insects fiom 

applications) considered here is ingestion of food items such as grasses, other gee 

vegetation, seeds, and insects that harbor clethodim residues as a result of direct p application or drift. For aquatic organisms, the major routes of exposure are consi ered 

to be via the respiratory surface (gills) or the integument. Aquatic plants may be e posed 

via direct uptake and adsorption. Estimated exposure concentrations for all organi ms 

are obtained through the use of several Agency exposure models. Note that only 

aeriallground spray and chemigation applications are depicted here; hand spray (s ot 

treatment) is expected to result in much less exposure. 1 

Figure 2. Ecological conceptual diagram for clethodirn I 

Stressor 

Source1 

Transport Direct Runoff1 Leaching 

Erosion drift (Infil :&tion/ 

Pathways A A - Percolation 

I 

Source/ Terrestrial Food 

Media 

Clethodim Applied by Ground SprayIAir Spray/Chemigation to Field 

Exposure 

Route 

1 

Receptors 

Upland and Surface Water 

+ 

ingestion 1 - ingestion 

Birds, Mammals, 

Reptiles, Terrestrial 

Phase Amphibians 

+ 

contact 

Beneficial 

l nsects 

I 

+ 

contacuroot 

uptake 

L------ t 

Upland and 

+ gill/integument + 

uptake and co tactlroot 

cot I Aquatic lhp?ke 

Vertebrates and 

Invertebrates L-r' T 

Reduced growth emergence and Reduced survival 

Reduced growth 
Based on an examination of the physicavchemical properties of clethodim, the fatg and 

disposition in the environment, and mode of application, a conceptual model was 

developed that represents the possible relationships between the stressor, 

receptors, and the assessment endpoints. For clethodim, the following 

hypothesis is being employed for this baseline risk assessment: 

Clethodim, when used in accordance with the label, results in potential 

adverse effects upon the survival, growth, and reproduction of non-target 

monocot plants exposed to runoff and drift from areas treated with 

clethodim. There are no data to assess the effects of clethodim exposure 

to passerine birds, estuarinelmarine organisms or the chronic risks that 

clethodim may pose to freshwater fish. Due to the fact that the sensitivity 

to chemicals may vary greatly between groupings of tqxa, and that the 

acute sensitivity of an organism may not accurately predict the chronic 

sensitivity, the Agency must make the assumption that there will be acute 

and chronic risks to species for which there are no data. Although 

clethodim is fairly non-persistent, it is mobile and is expected to occur in 

adjacent aquatic ecosystems on a continuous or recurrent basis. Also, the 

major toxic degradates of concern (clethodim sulfoxide and clethodim 

sulfone) are much more mobile and persistent than the parent. Thus, there 

is a possibility for exposure to terrestrial and aquatic organisms. 

In registration review, pesticide ecological risk assessments will follow the Agenc 

Guidelines for Ecological Risk Assessment, will be in compliance with the paper 

"Overview of the Ecological Risk Assessment Process in the Office of Pesticide 1 

Programs, U.S. Environmental Protection Agency" ("Overview Document") (Januky 

2004), and will be done in accordance with Section 7 of the Endangered Species ~bt. 

Results from aquatic and terrestrial exposure models (GENEEC 2, 

Rex) will be used to determine likely high-end exposure 

clethodim use (and compared with results from previous 

exposure model PRZM-EXAMS will likely be used 

screening model GENEEC 2 had been used in the most 

D333334 NU on Corn; 10/1/2007). These predicted 

determine the possible environmental effects of clethodim use. 

If the planned ecological risk assessment indicates that clethodim exceeds the 

Level of Concern for Listed species, either directly or 

Affect" determination will be made for the affected taxa (e.g., 

invertebrates, etc). A map of the clethodim use "footprint," 

types for which the LOC is exceeded will be generated, along with a narrative 
of the area outside the footprint where effects are expected to occur. These maps kd 

narrative descriptions will be provided to the U.S. Fish and Wildlife Service and the 

National Marine Fisheries Service (the Services) for them to determine which listdd 

species may be affected. The Agency will then consult with the Services, formal14 or 

informally, to refine the Effects Determination. , 

The Agency does foresee requiring additional ecological effects studies prior to 

conducting the planned assessments. Data gaps, uncertainties and potential paths 

for the assessment of clethodim are described below. 

aquatic, forestry, and residential turf use patterns when those uses can lead to exposure in 

estuarine andlor marine habitats. 

40 CFR Part 158 now requires acute toxicity data on one estuarinelmarine mollusk, one 

or runoff is expected to enter estuarine and marine ecosystems. ~ 

I 

The requested data would allow EPA to estimate acute risks to estuarinelmarine mollusks, I 

invertebrates, and fish, including defining an action area for endangered species. Risk miti ation 

strategies (e.g., determining the maximum clethodim application rate that results in an RQ elow 

the LOC) cannot be evaluated without these data. { ~ 

I 
Practic J Utility of the Data I 

How will the data be used? 

These data are needed for a registration review decision and for an endangered species asshssment, 

which will be conducted as part of that decision. The data would allow the Agency to dete ne 

acute risk to estuarinelrnarine organisms from water exposure to clethodim. The effects d a 

would be used to determine the likelihood that the acute risks can potentially impact aquat'c 

communities, either by direct effects or by indirect effects on other organisms by reducing heir 

food sources. f ~ 

I 

How could the data impact the Agency9s future decision-making? 

Risk assessment and mitigation strategies (e.g., determining the maximum clethodim appl' ation 

rate that results in Risk Quotients (RQs) below the Level of Concern (LOC)) cannot be ev luated 

without these data. If future endangered species risk assessments are performed without t se 

mollusks, fish, and invertebrates directly 

data, the Agency would have to assume that 

(and 

clethodim 

endangered species 

"may affect" 

from 

endangered saltwater 

other taxa 

I 

use of clethodim might need to be restricted in areas where endangered species 

The lack of these data will limit the flexibility the Agency and registrants have 

compliance with the Endangered Species Act and could result in use restrictions for cletho 

which are unnecessarily severe. 

Since the registration of clethodim, the Agency has worked to finalize its update to the da 

requirements in 40 CFR Part 158. These updated data requirements were promulgated in $ ctober 

2007. Now one freshwater invertebrate life-cycle study is required to support all terrestridl use 

patterns. i 

The Agency had conditionally required fish early-life stage and aquatic invertebrate life-c$cle 

studies (guidelines 850.1300, 850.1350, and 850.1400) for terrestrial food and nonfood, a uatic 

food and nonfood, forestry, and domestic outdoor uses. These studies still are not require for 

the applicability of the requirements. 

4 greenhouse food and nonfood, and indoor uses. The Agency has made several revisions to1 clarify 

I 

The first is to list the fish early-life stage and aquatic 

requirements in the data table; then identify each 

species. For the freshwater fish early-life stage and 

changed the conditional requirement for terrestrial and aquatic 

forestry uses to required, and changed the aquatic nonfood 

Previously, the freshwater invertebrate life cycle and fish early life stage tests 

required for terrestrial, aquatic (food crop and 

1984, one basis for the conditional nature of 

was required, depending on whether fish or 

However, when a pesticide enters the aquatic environment, both groups of organisms are 

exposed. Moreover, acute sensitivity is not 

when looking across different groups of 

results of acute testing. The change to 

to the fact that the previous "aquatic 
outdoor and aquatic nonfood residential. As the latter represents a much smaller use patte&, the 

Agency has reduced or eliminated the data requirement for aquatic nonfood residential uses. In 

addition, the Agency now requires both of these tests for all turf uses including residentlad, since 

exposure varies. I 

This change was warranted because the relative sensitivity of fish and invertebrates can v ry 

widely across chemicals. Previously, only the more sensitive of the two organisms, either ish or 

aquatic invertebrates, as determined by Tier I acute studies, was tested. However, since b th 

organisms are exposed when a pesticide enters an aquatic environment and the acute sensi ivity of 

an invertebrate may not accurately predict the chronic sensitivity in fish and vice versa, b th 

would suggest. 

Practical Utilify of the Data 

How will the data be used? 

species must now be tested for chronic effects. The Agency cannot make the assumption hat 1a 

chemical is not chronically toxic at much lower concentrations than some ratio of the LC5 value 

The data will be used to estimate potential risks to freshwater aquatic invertebrates and to keduce 

uncertainties associated with the current ecological risk assessment. , 

I 

How could the data impact the Agency's future decision-making? I 

I 

Without these data, the Agency cannot determine the levels of clethodim that could result i. adverse effects to freshwater aquatic invertebrates. The lack of these data will limit the flyxibility 

the Agency and registrants have in coming into compliance with the Endangered Species 

could result in use restrictions for clethodim which may otherwise be avoided, or which are 

unnecessarily severe. 

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Rationale for Requiring the Data 

Since the registration of clethodim, the Agency has worked to finalize its update to the data 

requirements in 40 CFR Part 158. These updated data requirements were promulgated in 

2007. Now one estuarinelmarine invertebrate life-cycle study is required to support all 

aquatic, forestry, and residential turf use patterns when those uses can lead to exposure in 

estuarine and/or marine habitats. 

Act, and 

4;Jj;$;$!?4it? "t:e&> 

~~;~b~ra;~6~,j*hh;~,*b:~~*~+~~' 

October 

terrestrial, 

I 

40 CFR Part 158 was revised to list the fish early-life stage and aquatic invertebrate 

studies as separate requirements in the data table; then identify each test organism 

or saltwater species. For the saltwater fish early-life stage and saltwater invertebrate lifedata requirements, the Agency requires testing of one fish species and one aquatic 

species, respectively, for the terrestrial, aquatic, forestry, and residential turf use 

estuarine or marine habitats may be exposed to the chemical. Previously, the saltwater 

invertebrate life cycle and saltwater fish early life stage tests were combined 

requirement with testing required of only the more sensitive species in acute studies. Hovlewr, 

when a pesticide enters the aquatic environment, both groups of organisms are exposed. 

Moreover, acute sensitivity is not a reliable indicator of chronic sensitivity, particularly wden 

looking across different groups of organisms, so chronic data are needed regardless of the results 

of acute testing. I 

This change was warranted because the relative sensitivity of fish and invertebrates can vary 

widely across chemicals. Previously, only the more sensitive of the two organisms, either fish or 
aquatic invertebrates, as determined by Tier I acute studies, was tested. However, since bbth 

organisms are exposed when a pesticide enters an aquatic environment and the acute sensitivity of 

an invertebrate may not accurately predict the chronic sensitivity in fish and vice versa, bgth 

species must now be tested for chronic effects. The Agency cannot make the assumption that a 

chemical is not chronically toxic at much lower concentrations than some ratio of the LCSp value 

would suggest. 

Practical Utility of the Data 

How will the data be used? 

The data will be used to estimate potential risks to estuarinelmarine aquatic invertebrates ~nd to 

reduce uncertainties associated with the current ecological risk assessment. 

How could the data impact the Agency's future decision-making? , 

Without these data, the Agency cannot determine the levels of clethodim that could result kn 

adverse effects to estuarinelmarine aquatic invertebrates. The lack of these data will limit )the 

flexibility the Agency and registrants have in coming into compliance with the Endangere id Species Act, and could result in use restrictions for clethodim which may otherwise be avoided, 

or which are unnecessarily severe. I 

estimates for freshwater fish, and allow it to define an action area for endangered species. Risk 

mitigation strategies (e.g., determining maximum clethodim application rate that results an RQ 

below the LOC) cannot be evaluated without these data. 4 I 

Since the registration of clethodim, the Agency has worked to finalize its update to the datp 

requirements in 40 CFR Part 158. These updated data requirements were promulgated in Qctober 

2007. Now one freshwater fish early life stage study is required to support all terrestrial, aquatic, 

forestry, and residential turf use patterns. I 

I 

40 CFR Part 158 was revised to list the fish early-life stage and aquatic invertebrate life-c cle 

studies as separate requirements in the data table; then identify each test organism as a fre hwater 

or saltwater species. For the freshwater fish early-life stage and freshwater invertebrate li e-cycle 

data requirements, the Agency requires testing of one fish species and one aquatic inverte rate 

species, respectively, for the terrestrial, aquatic, forestry, and residential turf use patterns. 1 

Previously, the freshwater invertebrate life cycle and freshwater fish early life stage tests ere 

combined under one data requirement with testing required of only the more sensitive spe ies in 7 

acute studies. However, when a pesticide enters the aquatic environment, both groups of , 

organisms are exposed. Moreover, acute sensitivity is not a reliable indicator of chronic 

sensitivity, particularly when looking across different groups of organisms, so chronic dat are 

needed regardless of the results of acute testing. 4 

This change was warranted because the relative sensitivity of fish and invertebrates can va~ 

widely across chemicals. Previously, only the more sensitive of the two organisms, either .- I fish or 
able to determine the appropriate mitigation for clethodirn. 

How could the data impact the Agency's futime decision-making? 

If future endangered species risk assessments are performed without these data, the Ag 

aquatic, forestry, and residential turf use patterns when those uses can lead to exposure in 

estuarine and/or marine habitats. 

i 

40 CFR Part 158 was revised to list the fish early-life stage and aquatic invertebrate life-c cle 

studies as separate requirements in the data table; then identify each test organism as a fre hwater 

or saltwater species. For the saltwater fish early-life stage and saltwater invertebrate life- ycle 

data requirements, the Agency requires testing of one fish species and one aquatic kverte rate 

species, respectively, for the terrestrial, aquatic, forestry, and residential turf use patterns 

estuarine or marine habitats may be exposed to the chemical. Previously, the saltwater 

\hen 

invertebrate life cycle and saltwater fish early life stage tests were combined under one daa 

requirement with testing required of only the more sensitive species in acute studies. Ho 4 ever, 

when a pesticide enters the aquatic environment, both groups of organisms are exposed. I 

Moreover, acute sensitivity is not a reliable indicator of chronic sensitivity, particularly w4en 

looking across different groups of organisms, so chronic data are needed regardless of the bults 

of a~ute'testin~. 

This change was warranted because the relative sensitivity of fish and invertebrates can v 

widely across chemicals. Previously, only the more sensitive of the two organisms, 
How could the data impact the Agency's future decision-making? 

registration review decision and for an endangered species 

assessment, which will be conducted as part of that decision. The effects data would be u ed to 

determine the likelihood that the chronic risks can potentially impact aquatic communities by 

direct effects on fish and their reproduction. By refining the assessment, the Agency wou d be 

able to determine the appropriate mitigation for clethodim. I 

i 

How could the data impact the Agency's future decision-making? I 

If future endangered species risk assessments are performed without these data, the Agenc 

would have to assume that clethodim "may affect" endangered fish directly (and I 

1 

endangered species from other taxa indirectly). Thus, use of clethodim might need to be 1 

restricted in areas where endangered species could be exposed. The lack of these data will. 

the flexibility the Agency and registrants have in coming into compliance with the Endanyed 

limit 

Species Act and could result in use restrictions for clethodim which are unnecessarily sevqre. 
unnecessary use restrictions, and the use of clethodim may need to be restricted in areas wgere 

endangered species occur unless these data are provided. 

The Agency will conduct a search of the open literature to ensure that all best ava 

science is utilized. The Agency uses the ECOTOX database as its mechanism for 

searching the open literature for ecological effects information. ECOTOX integri 

three previously independent databases - AQUIRE, PHYTOTOX, and TERRETC 

a system which includes toxicity data derived predominately from the peer-reviev 

literature, for aquatic life, terrestrial plants, and terrestrial wildlife, respectively. 

ible 

:s 

: - into 

d 

2 1 
There is specific information that will assist the Agency in refining the ecological 

assessment, including any species-specific effects determinations. The Agency is 

much interested in obtaining the following information: 

1. confirmation on the following label information l 

a. sites of application 

b. formulations 

c. application methods and equipnent 

d. maximum application rates 

e. frequency of application, application intervals, and maximum nurn er of 

applications per season 

f. geographic limitations on use 

relevant crops) 

3. use history 

national, state, and county 

! 

2. use or potential use distribution (e.g., acreage and geographical distributio of 

4. median and 9oth percentile reported use rates (lbs. a.i.lacre) from usage dat - 

5. application timing (date of first application and application intervals) by cr I p - 

national, state, and county 

6. sub-county crop location data 

of-way) 

! 

7. usageluse information for non-agricultural uses (e.g., forestry, residential, r ghts8. directly acquired county-level usage data (not derived from state level data 

i 

a. maximum reported use rate (lbs. a.i./acre) from usage data - county 

b. percent crop treated - county 

c. median and 9oth percentile number of applications - county 

I 

d. total pounds per year - county 

e. the year the pesticide was last used in the countylsub-county area 

f. the years in which the pesticide was applied in the countylsub-coun y area 

9. typical interval (days) 

10. state or local use restrictions 

t 

11. ecological incidents (non-target plant damage and avian, fish, reptilian, am hibian 

and mammalian mortalities) not already reported to the Agency Ip 

12. monitoring data I 

The analysis plan will be revisited and may be revised depending upon the data av 

in the open literature and the information submitted by the public in response to th 

opening of the Registration review docket. 
Flickinger, E.L., D.H. White, C.A. Mitchell, and T.G. Lamont. 1984. ~onocrotobhos 

and clethodim residues in birds as a result of misuse of organophosphates i 

Matagorda County, Texas. J. Assoc. Off. Anal. Chem. 672327-828. 

U. S. Environmental Protection Agency. 1 998. Guidelines for Ecological Risk 

Assessment. Risk Assessment Forum, Office of Research and Developme 

Washington, D.C. EPAl630lR-951002F. April 1998. 

U.S. Environmental Protection Agency. 2000. Risk Characterization Handbook. 

Science Policy Council, U.S. Environmental Protection Agency, Washingt 

D.C. 20460. EPA 100-B-00-002. December 2000. 

U.S. Environmental Protection Agency. 2004. Overview of the Ecological Risk 

Assessment Process in the Office of Pesticide Programs, U.S. 

Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide 

Programs, Washington, D.C. January 23,2004. 

Protection Agency. Endangered and Threatened Species Effects Determin