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



### MEMORANDUM OFFICE OF CHEMICAL SAFETY AND POLLUT ION PREVENTION



### November 26,2013

PC Code: 105401 DP Barcode: 408647
SUBJECT: Clomazone : Ecological Risk Assessment for IR-4 Proposed New Uses for Brassica (Head and Stem Subgroup SA , Peas, and Rhubarb 

### FROM: Kristina Garber, Senior Biologist f...rJames Lin, Environmental Engine ERB2/EFED (7507P) 

### THROUGG;- R. David Jones, Ph.D. Senior Agronomist 

# JS-A Jean Holmes, Risk Assessment Process Leader Brian Anderson, Branch Chief 

### h 

### A.O/ 

# It, ERB2/EFED (7507P) 

### f/try'
- 

### TO: Sidney Jackson, Risk Manager Reviewer Barbara Madden, Risk Manager, RM 

### 05 Erik Kraft, Risk Manager Reviewer, RM 25 Kable Davis, Risk Manager RM 25 RSB/RD (7504P) 

### I. Risk Conclusions For the proposed new uses on peas, brassica and rhubarb, the primary risks of clomazone are for non-target plants in terrestrial and wetland habitats. Clomazone exposure via spray drift, runoff and volatilization poses a risk of effects to growth ofplants in non-target terrestrial and semiaquatic habitats. This risk i s supported by available ecological incidents indicating that clomazone exposure may have caused effects to terrestrial plants hundreds offeet to 2 miles from treated sites after volatilizing. There is also some concern for mammals, since some application rates result in exposures of concern for some mammals. Clomazone applied at 1.5 lb a.i./A poses a risk ofacute exposure to small listed mammals (that consume short grass) and ofchronic exposure to mammals (that consume grass). Application rates of0.81 lb a.i./A would not pose risk concerns for mammals. This indicates that the proposed use on rhubarb poses a risk to mammals and the proposed uses on peas and brassica do not pose a risk of concern.

### Estimated exposures resulting from the proposed new uses are not expected to impact survival, growth or reproduction ofbirds, terrestrial-phase amphibians, reptiles, fish, aquatic invertebrates and aquatic plants. 

### II. Use Information This IR-4 Petition, 2E8136, proposes the following new uses to Command 3ME label (Reg. No

. 279-3158) : (1) Brassica (head and stem subgroup 5A)- Apply broadcast at 0.67 pints per acre (0.25 lb ai/ac); This group includes broccoli, Chinese broccoli, Brussels sprouts, cabbage, Chinese (or napa) cabbage, Chinese mustard cabbage, cauliflower, cavalo broccoli, and kohlrabi. (2) Rhubarb- Apply broadcast at 4.0 pints per acre (1.5 lb ai/ac) to dormant rhubarb prior to leaf emergence; and (3) Southern pea- Apply broadcast at 1

.3 pints per acre (0.49lb ai/ac). Southern peas (Vigna unguiculata) are also known as black-eyed peas, field peas, and cow peas. The following precautions and restrictions are notes in the label: • Do not apply aerially or through irrigation equipment. • Observe all buffer restrictions

. • Do not apply Command 3ME within 1,200 feet ofthe following areas: towns and housing developments, commercial fruit/nut or vegetable production, commercial greenhouses or nurseries. • Before application, determine air movement and direction. • Do not apply in winds above 10 miles per hour. • Do not apply Command 3ME herbicide to non-field areas including fence rows, waterways, ditches , and roadsides. • When moving spray equipment to noncontiguous sites, do not apply spray or drip from tanks, hoses, fittings or spray nozzles and tips. • Do not apply when weather conditions favor drift. • Use a minimum spray volume of 10 gallons per acre. • Use the lowest possible boom height while maintaining a uniform spray pattern, in conjunction with nozzle type, size, operating pressure and volume that meet a droplet size classification ofcoarse or greater. 

### III. Environmental Fate Summary Clomazone is a semi-volatile compound of low to high persistence in various environmental compartments and ofmoderate mobility in soil. The major exposure route ofconcern is displacement ofsorbed clomazone from soil by water vapor after rain or during episodes ofhigh humidity, volatilization from the soil, and downwind transport ofclomazone vapors. Once displaced from soil clomazone is not expected to be persistent in air for more than a couple of days.

### IV. Risks to Terrestrial Animals T-REX was used to estimate upper bound exposure to birds and mammals to clomazone through consumption offood items located directly on the treated area. An application rate of 1.5 lb a.i./ A was simulated to represent the highest ofthe proposed new uses considered in 

### this assessment. The default foliar dissipation half-life of35-d was used

. Note that this value is likely an overestimate ofthe true dissipation ofclomazone due to volatility; however, since only one application rate is simulated, the half-life does not impact estimated environmental concentrations (EECs) and risk quotients (RQs). To represent exposure, the highest EECs generated by T-REX are used below. These values are representative of small animals that consume short grass. The acute and chronic endpoints used to represent birds and mammals are listed in 

### Table 1. 

### Detailed descriptions ofthese studies are provided in the registration review assessment for clomazone. For this assessment, birds are used as surrogates to represent terrestrial-phase amphibians and reptiles. 

### Table 1. Summary of Specific Measurement Endpoint Values Selected to Calculate RQ V I 

### t E I t 

### Ri 

### k**~** 

# o· d d M I 

### A t E d

. 

### ts

a ues o va ua e s or tr san amma ssessmen n IP01D 

# . Test Species Value ACC/ Classificati Assessment Measurement MRIO on Endpoint Endpoint Survival and Acute mortality: Mallard duck (Anas >2,230 mg ai/kg-bw Ace II Acceptable Reproduction of most sensitive p/atyrhynchos) 248475 Birds, Reptiles avian acute oral and toxicity, LD.so Amphibians (single-dose) Mortality: most Bobwhite quail > 4,990 mg ai/kg-diet Ace II Acceptable sensitive subacute (Colinus virginianus) (ppm ai) 248475 avian LC.so and Mallard duck Reproduction : Bobwhite quail I ,020 mg ai/kg-diet (or MRlD Acceptable most sensitive ppm ai) 45 17810 1 avian reproductive NOAEC Survival and Acute mortality : Norway rat (Rattus I ,369 mg ai/kg-bw Ace# Acceptable Reproduction of most sensitive norvegicus) (female) 00117121 Terrestrial acute oral toxicity, Mammals LD.so (single-dose) Reproduction: Norway rat I000 mg ai/kg-diet Ace II Acceptable most sensitive 00151108 reproductive 84.4 mg a.i./kg-bw NOAEC/NOAEL [based on decreased body weight in adults and offspring) 

### Acute dose-based exposures ofbirds to clomazone at 2230 mg!kg-bw 

### (LDso >2,230 mg ailkgbw) did not cause mortality or sublethal effects. This test dose was an order of magnitude above the highest dose-based EEC that would be predicted for this use, which is 410 mg/kg-bw.Similarly, for dietary-based sub-acute exposure, no mortality or sublethal effects were observed in birds dosed with 4990 mglkg-diet, which is well above the highest EEC predicted by T-REX for this use, which was 360 mg/kg-diet. The maximum acute dose-based EEC for mammals estimated by T-REX was 343 mglkg-bw, which is also an order of magnitude below the unadjusted LDso for rats, 

### i.e., 1369 mglkg-bw. Dividing the EEC by the adjusted LDso for small mammals (3009 mg/kg-bw) yields an RQ of 0.11, which is below the acute LOCs for non-listed mammals (O.S) but exceeds the LOC for listed mammals (0.1). This RQ applies to listed small (15 g) mammals that consume 100% short grass at the upper bound exposure value. No other food items 

### (i.e., tall grass, broadleafplants, seeds, arthropods) yield risk concerns for small, medium (35 g) or large (1000 g) mammals (listed and non-li sted species). On a chronic exposure basis, the NOAEC values for birds and mammals exposed to clomazone were 1020 and 1000 mg/kg-diet, respectively. The highest dietary-based EEC generated by TREX for this proposed use is 360 mglkg-diet. This EEC generates chronic RQs for birds and mammals of0.4, which is below the LOC of 1. Dose-based RQs for mammals exceed the LOC for small and medium mammals that consume short grass (Table 2). An application rate of0.81 lb a.i./ A would not exceed any LOCs for mammals. Table 2. Dose-based chronic RQs for mammals exposed to clomazone applied at 

### 1.5 lb 

### a.i./A.

Food item SmaU(ISg) Medium (35 e:) Large (1000 g) Short Grass 1.9• 1.6* 0

. 85 Tall Grass 0.85 0.72 0.39 Broadleafplants 1.0 0.89 0 .48 Fruits/pods 0.12 0. 10 0

.05 Arthropods 0

.72 0.62 0.33 Seeds O.Q3 0 .02 O.oJ *RQ exceeds chrome LOC. V. Risks to Aquatic Animals The model input parameters for PES based on the general chemical and environmental fate data for clomazone are listed in Table 3. The model input parameters used in PES to simulate clomazone application and crop management practices are provided in Table 4. The proposed highest rate is l.S lb ai/ac for rhubarb use. Rhubarb belongs to the Crop Group 4B for leaf petioles subgroup. The representative modeling scenario is MI beans. Clomazone should 

### be applied during dormant prior to leafemergence. The scenario assumes the emergency date of June 1, so the application rate is adjusted to May 1S

. The EECs of clomazone are provided in Table 5. Table 6 includes the acute and chronic endpoints used to derive RQs for fish and invertebrates inhabiting fresh and salt water areas (Table 7). Acute and chronic RQs for aquatic animals do not exceed LOCs

.

### T 

### bl 3 PES Ch

. II 

### a e 

# .**emu~**

### a nputP t 

### ti 

### Cl arame ers or omazone. Input Parameter Value Source/comment Molecular weight 239.70 Vapor pressure 1.44 x 10-4 torr Ahrens, 1994 (Herbicide Handbook, WSSA, 7th ed.) Solubility in water 1100 mg/L Ahrens, 1994 Hydrolysis half-life stable at pH 5, 7, 9 Ace. No. 248476, ref. 29 Aqueous Photolysis half-life 87 days Ace. No. 073672 Aerobic Soil metabolism half

- 80 days (90% UCL on mean Ace. No. 248476, ref. 30 life of35, 65, 74 days) Anaerobic aquatic metabolism 44 days for total system MRJD 44348403 half-life Aerobic Aquatic metabolism 79 days (90% UCL on mean MRID 44348404, 44348405 half-life of75, 64, 40

.3 days) Organic carbon norrnalized 300 Ahrens, 1994 soil partition coefficient Koc Henry's Law Constant 4.13 x 10-8a tm -m3/mol Calculated from vapor pressure and solubility Air Diffusion Coefficient 3802 cm 2/day Calculated f rom molecular weight, Da= l .SS/((MW)0.65) (Schwarzenbach, Gschwend, Imboden, 1993, p . 195) Enthalpy ofVaporization 20 kJ/mol PRZM default value Chemical Application Method 1 (broadcast, surface applied) Spray Drift 1% for ground application Guidance for ground applications Application Efficiency**9~/o** Guidance for soil applications without incorporation 

### Table 4

. PRZM Scenario and Input Parameters Describing the Maximum Proposed Clomazone Use Patterns. Application App. Rate App. Depth, CAM IPSCND Application Use Scenario per Efficiency/ Date (lbs a.i.!A) Year em Input Input Spray Drift Rhubarb MI Beans 05/15 1.68 1 4 1 I 0.99/0.01 

### T 

### bl S 

### PE 1. 10

a e 

# . -m- 

### -year A


### . EEC fCI .quatic so omazone Use Scenario Peak (llg/L) 21-day Mean 60-day Mean (f.lg/L) (f.li/L) Rhubarb Ml Beans 16

.40 15.53 13.98 Sediment Pore Water Rhubarb Ml Beans 6.44 6

.40 6.30Table 

### 6. Summary of Speci

. fic Measurement Endpoint Values Selected to Calculate 

### RQ 

### VI tE 

### I tRik f< fib d ti. b 

### A Ed

a ues o va ua e s or IS an aqua c mverte rate ssessment n lpomts. Selected Measurement Endpoint Value and Source Assessmen t Measurement Species Toxicological Endpoint 1 Source I Endpoint Endpoint and Effect(s) Study (ppb a.i. or !Jg a.iJL) Classification Survival and Acute mortality : Rainbow trout 19,000 Ace# 248475 reproduction of most sensitive (Oncorhynchus Rhoderick, 1982 fres hwater acute freshwater mykiss) Acceptable vertebrates (fish, fish 96-h LC$0 amphibians) Reproduction : 2290 Ace# 073830 Anon, 1985 most sensitive Acceptable early life stage (ELS)NOAEL Survival and Acute mortality : Sheepshead 40,600 Ace# 073830 and reproduction of most sensitive minnow 073671 Surprenant 1985 marine/ acute freshwater (Cyprinodon I estuarine fish fish 96-h LCso variegatus) Supplemental Reproduction: 4,890 Based on ACR (8

.30) mos t sensitive from rainbow trout data early life stage (ELS)NOAEL Survival and Acute mortality : Water flea 5,400 Ace# 248475 Graney, reproduction of most sensitive (Daphnia 1982 I freshwater acute freshwater magna) invertebrates invertebrate 48-h Acceptable or 96-h ECso or LCS<l Reproduction : 2 ,200 Ace# 073997,073616 most sensitive Spare and Graney, 1982 reproductive Acceptable NOAEL Survival and Acute mortality : Mysid shrimp 566 Ace # 263080 Williams, reproduction of most sensitive (Americamysis 1986/ marine/ acute invertebrate bahia) estuarine 48-h or 96-h ECso Acceptable invertebrates or LCso Reproduction 231 Based on ACR (2.45) NOAEC from D

. magna data

T bl 7 A t d h 

### .k tients for aquatic animals

.

a e 

# . cue an c rome r1s

.quo Taxa Acute Chronic FW fis h 0

.00086 0.0061 SW fish 0.00040 0.0029 FWinverts 0.0030 0

.0071 SWinverts 0.029 0.067

### VI. Risks to Plants Applications ofdomazone may result in offsite transport via spray drift, volatilization and runoff. As a result, non-target plants may be exposed to this herbicide

. Table 8 summarizes the most sensitive seedling emergence endpoints for monocots and dicots

. These values are used to determine risks ofnon-target plants exposed to clomazone through offsite transport via spray drift and runoff RQs generated using the TerrPlant model are provided in Table 9. RQs exceed the LOC for listed and non -listed species ofplants inhabiting terrestrial and semi-aquatic habitat. RQs for aquatic plants (also provided in Table 9) do not exceed the LOC for non-listed or listed species. At this time, EFED does not have a standard approach for estimating the amount ofclomazone that redeposits on non-target areas after volatilization. Therefore, exposure ofplants to clomazone through volatilization and redeposition is not quantified

. Based on availab le ecological incidents indicating that clomazone exposure may have caused effects to terrestrial plants hundreds offeet to 2 miles from treated sites after volatilizing, this exposure pathway is of concern.
Table 

### 8. Summary of Spetific Measurement Endpoint Values Selected to Calculate 

### RQ V I E I Ri 

### k fi 

### T . I d A

. PI A E d

a ues to va uat e 

### s or errestna an**quattc** ant ssessment n lpomts Selected Measurement Endpoint Value and Source Assessment Measurement Species Toxicological Endpoint Source I Endpoint Endpoint and Effect(s) Study Classification Survival and Monocots: the most Onion Seedling Emergence MRlD 4155750 I biomass ofnon- sensitive seedling (Allium cepa) IC25 

### = O.Q31 lbs ail A Chetrem, 1990 I target plants in emergence or vegetative NOAEC 

### =0.0062 lbs ail A terrestrial and vigor IC 25 for non-listed Acceptable semi-aquatic and its associated Most sensiti ve endpoint was height areas NOAEC for listed species Dicots: the most sensitive Lettuce Seedling Emergence MRlD 42165705 seedling emergence or (La ctuca sativa) 1C25 = 0

.0037 lbs ail A Chetrem, 199 I I vegetative v i gor IC25 for NOAEC "' 0

.0008 lbs ail A non-listed and its Acceptable associated NOAEC for Most sensitive endpoint was dry listed species weight Survival and Non-vascular species: the Freshwater 5-d ICso 

### = 167 ppb ai MIRD 4499480 I biomass of most sensitive biomass d iatom (Navicula 5

-d NOAEC 

### =2 3. 6 ppb ai Kranzfelder and aquatic vascu lar ICso for non-listed and its pel/icu / osa) Goble, 1999 / and non- associated NOAEC for vascular plants listed species Acceptable Vascular speci es : the Duckweed 7

-d ICso 

### = 30,200 ppb ai Miche l et al

., 2004 most sensiti ve biomass (Lemn a 7

-d NOAEC 

### =7 ,300 ppb ai (Published) I IC50 for non-listed and its paucicostata) associated NOAEC for Supplemental list ed species

### T bl 9 RQ I t 

### a e 

# . s or plan s. Habitat Plant Type Listed Status Brassica Peas Rhubarb Monocot non-listed 0.48 0.95 2.9* Terrestrial Monocot listed 2.4* 4.7* IS* Dicot non-listed 5.6* 11* 33* Dicot listed 19* 37* 110* Monocot non-listed 4.1* 8.1* 25* Semi-Aquatic Monocot listed 21* 40* 120* Dicot non-listed 47* 93* 280* Dicot listed 160* 310* 960* Non-vascular non-listed 0.10 Aquatic Non-vascular listed Not calculated 0.69 Vascular non-listed 0.00054 Vascular listed 0.0022 

### *Exceed plant LOC (1.0)

.