U. S. ENVIRONMENTAL PROTECTION AGENCY 

Washington, D.C. 20460 

OFFICE OF 

PREVENTION, PESTICIDES 

AND TOXIC SUBSTANCES 

I 

DP BARCODE: D27023 1, D284046 DATE: November 4,2003 

CHEMICAL: Flufenpyr-ethyl 

PC Code 108853 1 Sponsor: Valent USA Corporation 

SUBJECT: Data Review and Addendum for FLUFENPYR-ETHYL (S-3153 

WDG Herbicide) on Terrestrial Animals, Aquatic Organisms, and 

Plants. 

FROM: 

THRU: 

TO: 

Stephen Carey, Biologist 

Environmental Risk Branc 

Ben Smith, Branch Chief 

Stephanie Syslo, RAPL 

Environmental Risk Branch IIIIEFED 

Dianne Morgan, Review Manager 

Joanne Miller, PM 23 

Herbicide Branch 

Registration Division 

As indicated in our "New Chemical Review for the us? of flufenpyr-ethyl on Sugarcane and 

Soybeans, dated September 11, 2003", our analysis was based on screening level review of the 

ecological effects studies. We have now completed the peer review of these studies. Copies of 

each study's data evaluation records (DERs) are attached. Peer review has identified the need for 

adjustments in the toxicity endpoints originally reported for aquatic vascular plants and for 

chronic avian effects. 

In the case of the chronic avian effect level, we previously had projected the potential for chronic 

risk at 164 ppm (a level well above the peak chronic EEC of 12 ppm). Subsequent analysis 

establishes a much higher NOAEC of 1040 ppm. Consequently, it is even less likely that flufenpyr 

poses a chronic avian effect. 

The other numbers which changed were the effect levels for aquatic vascular plants. In the 

original risk assessment, we reported exceedances of the LOC for terrestrial plants, but had not 

anticipated any issues with the aquatic plants. In fact, we had not even performed crop specific 

modeling to devise RQs since the LOC was not exceeded. Subsequent analysis has identified a 

EC50 for duckweed at 0.013 mg/L and a reduction of the NOAEC from 0.003 mg/L to 0.00078 

mg/L. The NOAEC for the S-3 153-acid degradate decreased from 0.003 mg/L to 0.0003 mg/L. 
These levels now result in an LOC exceedance for aquatic vascular plants. We, therefore, 

performed more crop specific modeling of the EEC's. All of the resulting changes in the science 

chapter which result from these collective changes are identified in green text in the attachments. 

Based on the changes, the RQs for aquatic vascular endangered plants now vary from 2 to 5 for 

the three crops of interest. Nevertheless, endangered aquatic vascular plants are unlikely to be 

found in proximity to the three proposed uses. Consequently, these changes would not appear to 

be significant from the standpoint of risk management considerations, subject to our previously 

expressed concerns about missing studies. 

Do not hesitate to contact us if you have any questions relating to this submission. 
Attachment 

The Environmental Fate and Effects Division (EFED) has completed its review of ecological 

effects data submitted by Valent U.S.A. Corporation on flufenpyr-ethyl. In addition, degradate 

studies were also submitted because the parent compound degrades rapidly and is less persistent 

than the two degradates: S-3 153 acid and S-3 153-4-OH in the environment. The flufenpyr-ethyl 

studies included acute avian oral (MRID 451188-15), subacute avian dietary (MRIDs 451188-16 

and 45 11 88- 17) and chronic avian reproduction (MRIDs 45 1 188- 18 and 45 11 88- 19); acute 

honeybee contact (MRID 45 1 190- 18); acute freshwater fish (MRIDs 45 11 88-20 and 45 1 188-2 1) 

and invertebrate (MRID 451 188-23); chronic freshwater fish early life-stage (MRID 451 188-27) 

and invertebrate life-cycle (MRID 45 11 88-26); acute estuarinelmarine fish (MRID 45 1 188-22) 

and invertebrate (MRIDs 45 1 188-24 and 45 1 188-25); tier I1 terrestrial plant seedling emergence 

(MRID 45 1190-16) and tier I1 terrestrial plant vegetative vigor (MRID 45 1190- 17); tier I1 

aquatic vascular plant (MRID 45 1 190-1 I), tier I1 aquatic non-vascular plants (MRIDs 45 1 190- 

12, -13, -14, -15). The degradates of S-3153 acid (MRID 452423-04) and S-3153-4-OH (MRID 

452423-03) tier I1 aquatic plant studies with the duckweed, Lemna gibba, are included as well. 

Toxicity studies on animals and aquatic plants were conducted using technical grade active 

ingredient while studies of terrestrial plants were conducted using formulated end product (S3 153 WDG herbicide; 50% a.i.). 

Tables 1 through 16 (excluding Tables 4 and 5 for mammals) provide a brief summary of each 

study's toxicity endpoint(s) and classification. As indicated in the memorandum, changes are 

highlighted as green text. If you have any questions or comments regarding these studies, please 

do not hesitate to contact us. 

Toxicity to terrestrial animals and insects, aquatic organisms, and plants 

Table 1. Acute Toxicitv of Flufen~vr-ethvl to Northern bobwhite. 

Avian Acute Oral Toxicity - 

Species % ai Toxicity value Toxicity category MRID no. Study classification 

Northern bobwhite quail 97 LD50 >22502 mglkg practically nontoxic 45118815 core' 

(Colinus virginianus) 

' Core (study satisfies guideline). Supplemental (study is scientifically sound, but does not satisfy guideline) 

no mortality reported 

Table 2. Subacute Dietary Toxicity of Flufenpyr-ethyl to Northern bobwhite and Mallard ducks. 

Avian Subacute Dietary Toxicity 

Species % ai Toxicity value Toxicity category MRID no. Study Classification 

Northern bobwhite quail 97 LC50 >56201 ppm practically nontoxic 45118817 core 

(Colinus virginianus) 

Mallard duck LC50 >56201 ppm practically nontoxic 45118816 core 

(Anas platyrhynchos) 

' no mortality reported 
Avian reproduction studies using the TGAI are required for flufenpyr-ethyl because multiple 

applications may subject birds to repeated or continuous exposure during or preceding the 

breeding season. The preferred test species are the mallard duck and northern bobwhite. Results 

indicate an NOAEC of 1040 ppm and an LOAEC of >lo40 ppm (Table 3). The guideline (71-4) 

is fulfilled (MRID 45118818, -19). 

Table 3. Chronic Toxicity of Flufenpyr-ethyl to Bobwhite quail and Mallard ducks. 

Avian Reproduction 

Species % ai NOAEC (ppm) LOAEC Affected endpoints MRID no. Study classification 

Northern bobwhite 97 1040 >lo40 none 

Mallard 97 1040 > 1040 none 

451188-19 core 

451188-18 core 

' Core (study satisfies guideline). Supplemental (study is scientifically sound, but does not satisfy guideline). Invalid (study is scientifically unsound 

and does not satisfy guideline). 

Table 6. Acute Contact Toxicity of Flufenpyr-ethyl to Honeybees. 

Nontarget Insect Acute Contact Toxicity 

Species % ai LD50 Toxicity category MRID no. Study classification 

Honey bee tech >25 pglbee' practically nontoxic 45119018 core 

' 33% mortality in some treatment levels were reported 

Table 7. Acute Toxicity of Flufenpyr-ethyl to Freshwater Fish. 

Freshwater Fish Acute Toxicity 

Species % ai LC50 Toxicity category MRID no. Study classification 

Rainbow trout 96.8 3.75 mg/L moderately toxic 451188-21 core 

Bluegill sunfish 97 2.537 mgL moderately toxic 45 1 188-20 core 

Table 8. Chronic Toxicitv of Flufen~vr-ethvl to Freshwater Fish. 

Freshwater Fish Early Life-Stage Toxicity Under Flow-through Conditions. 

Soecies % ai NOAEC LOAEC Affected Endwints MRID No. Study Classification 

Rainbow trout 96.8 0.44 mg/L 0.92 mg/L growth 451188-27 supplemental' 

test concentrations were below detectable limits for approximately 20 hours on Day 22-23. 

Table 9. Acute Toxicity of Flufenpyr-ethyl to Freshwater Invertebrates. 

Freshwater Invertebrate Acute Toxicity Under Flow-through Conditions 

S~ecies % ai EC50 Toxicity category MRID No. Study Classification 

Water flea 96.8 >3 mg/L nla 451 18823 supplemental1 

environmental test conditions were higher than the guideline recommendations. 
Table 10. Chronic Toxicity of Flufenpyr-ethyl to Freshwater Invertebrates. 

Freshwater Invertebrate Life-Cycle Toxicity Under Flow-through Conditions 

Species %ai NOAEC LOAEC Affected endpoints MRID no. Study classification 

Water flea 96.8 0.46 mg/L 1.2 mg/L reproduction 45118826 core 

Table 11. Acute Toxicity of Flufenpyr-ethyl to EstuarineJMarine Fish 

Estuarinemarine Fish Acute Toxicity Under Flow-through Condition 

Species % ai LC50 Toxicity category MRID no. Study classification 

Sheepshead minnow 97 >2.7 mg/L nla 451 188-22 core 

Table 12. Acute Toxicity of Flufenpyr-ethyl to EstuarineIMarine Invertebrates 

Estuarinemarine Invertebrate Acute Toxicity Under Flow-through Conditions 

Species % ai EC50 Toxicity category MRID no. Study Classification 

Mysid shrimp 

- - --- - 

97 2.08 ma moderately toxic 45 1 188-25 core 

Eastern oyster (shell deposition) 97 s2 mg/L n/a 45 1 188-24 core 

Table 13. Toxicity of Flufenpyr-ethyl To Terrestrial Plants using Tier I1 Seedling Emergence. 

Nontarget Terrestrial Plant Seedling Emergence Toxicity (Tier 11) 

Species % ai EC25 (Ibs ai/A) NOAEC Endpoint Affected1 MRID No. Study Classification 

50.0 451 190-16 

Monocot- Corn >0.029 0.029 none core 

Monocot- Oat 

Monocot- Onion 

Monocot- Ryegrass 

Dicot-Soybean 

Dicot- Lettuce 

Dicot- Radish 

Dicot-Cucumber 

Dicot- Cabbage 

none 

weight 

none 

none 

weight 

weight 

none 

weight 

core 

core 

core 

core 

core 

core 

core 

core 

Dicot- Tomato 20.029 0.029 none core 

only the most sensitive endpoint is tabulated 
, 

Table 14. Toxicity of Flufenpyr-ethyl To Terrestrial Plants using Tier I1 Vegetative Vigor. 

Nontarget Terrestrial Plant Vegetative Vigor Toxicity (Tier 11) 

Species % ai EC25 (Ibs ai/A) NOAEC Endpoint Affected1 MRID No. Study Classification 

Monocot- Corn 20.029 0.029 none core 

Monocot- Oat >0.029 0.029 none core 

Monocot- Onion 0.0056 0.0032 height core 

Monocot- Ryegrass >0.029 0.029 none core 

Dicot-Soybean >0.029 0.029 none core 

Dicot- Lettuce 0.0001 8 0.00004 weight core 

Dicot- Radish 

Dicot-Cucumber 

0.0021 0.001 1 weight 

0.00061 0.00012 weight 

core 

core 

Dicot- Cabbage 0.0023 0.001 1 weight core 

Dicot- Tomato 0.00009 0.00004 weight core 

only the most sensitive endpoint is tabulated 

Aquatic plant testing is required for any herbicide that has outdoor non-residential terrestrial uses 

and that may move off-site by runoff (solubility >10 ppm in water), andlor by drift (aerial) or that 

is applied directly to aquatic use sites (except residential). Normally, tier I testing with the TGAI 

is conducted on duckweed (Lemna gibba), a vascular species, and a green algae (Skeletonema 

costatum), a nonvascular species. Then, tier I1 testing is required if either species in Tier I is 

inhibited 50% or more, and also includes Selenastrum capricomutum, Anabaenaflos-aquae, and 

a freshwater diatom. In this case, the registrant chose to conduct Tier I1 testing even though it 

may not have been triggered. Results of Tier I1 toxicity testing with the vascular aquatic plant, 

duckweed, and the most sensitive non-vascular aquatic plant, the EC5Os were 0.013 and 0.009 

mg/L respectively (Table 15). The guideline (123-2) is fulfilled with all five species tested (MRID 

451190-11, -12, -13, -14, -15). 

Table 15. Toxicity of Flufenpyr-ethyl to Aquatic Plants using Tier 11. 

Nontarget Aquatic Plant Toxicity (Tier 11) 

Species % ai EC50 NOAEC MRID no. Study classification 

Vascular species: 

Duckweed 99.1 0 0 13 1ndL' 0.00078 mdL' 451190-11 core 

Nonvascular species: 

Anabaena flus-aquae 99.1 >0.5 mg!L1 0.031 rng/L1 451190-14 core 

Skeletonenla costaturn 97 0.01 1 ma 0.00081 mg/L 451190-12 core 

Selenastrum capricornutum 99.1 0.009 mg/L1 <0.0063 mgL1-? 451 190-15 core 

Navicula pelliculosa 97 0.18 ma 0.032 mg!L 451190-13 core 

' nominal concentration 

the NOAEC is below the lowest tested concentration 
Additional duckweed toxicity studies were also submitted by the registrant on flufenpyr-ethyl's 

degradates, S-3153-acid and S-3153-4-OH. Results of Tier I1 toxicity testing indicate the EC5Os 

were 0.0063 and >0.03 mg ae/L, respectively (Table 16) The studies were determined to be core 

(MRID 452423-03, -04). 

Table 16. Toxicity of Degradates to Duckweed. 

Nontarget Aquatic Plant Toxicity (Tier 11) 

Specles % a1 Degradahon IdenWica~on EC50 (mg a eJL) NOAEC MRID no Study classificahon 

Duckweed 98 7 S-3153 ac~d 0 0063 0 0003 452423-04 core 

Duckweed 97 5 S-3153-4-OH SO 03 0 03 452423-03 core 

Section A: Summary of Risks to Birds 

Page 20 of Science Chapter 

Toxicity: 

Flufenpyr-ethyl is nontoxic to birds on both an acute (LD,, >2250 mglkg) and subacute dietary 

basis (LC,, >5620 mglkg of diet). Nor does it pose the risk of adverse effects on a chronic 

exposure basis (NOAEC = 1040 ppm). 

Page 11 

Risk Characterization for Animals: 

The proposed use sites of flufenpyr-ethyl are not likely to pose any potential acute or chronic risk 

to birds or mammals since toxicity tests indicate that they are not sensitive to exposure to the 

active ingredient. In the toxicity tests, no acute effects are observed after exposure to the highest 

concentration tested according to testing guidelines. Because the NOAEC is 1040 ppm, problems 

are not anticipated even under a screening level assessment which identifies a peak modeled 

concentration of flufenpyr-ethyl on short grass of 12 ppm. 

Page 21 

Estimates of Risks to Birds and Mammals: 

The toxicity test values (i.e., measurement endpoints) used in the acute and chronic risk 

quotients are derived from the results of required studies. The EEC, toxicity, and risk quotient 

values are provided below in Table 10. 
Table 10 - Toxicity, Exposure, and Risk Quotient Values of Flufenpyr-ethyl(2 applications of 0.027 lb 

ai/A, 10 days interval, 35 day half-life) f pecies Risk Quotients 

(ppm) (RO) ' 

Northern bobwhitel Mallard >2250 mglkg 11.8 <0.01 

duck-Oral 

I Marnmals-Oral and Reproduction 1 >5000 mgkg / 1463 ppm I 11.8 1 ~0.01 / <0.01 

' Based on ELLFATE model (Detailed in appendix VIII) 

Bobwhi taallard-Dietary 

Northern bobwhite-Reproduction 

Bird and Mammal Risk Assessment Summary 

No acute or chronic LOCs were exceeded for birds and mammals; the risks are believed to 

be negligible. 

>5620 ppm 

1040 ppm 

Chronic risks were evaluated using maximum estimated environmental concentrations based on a 

Mallard duck NOAEC of 1040 pprn (Table 6). Even assuming no degradation between 

applications, chronic risk to bird is believed to be negligible. The chronic risk quotient for a 

broadcast application of non-granular products are tabulated below. 

Table 6. Avian Chronic Risk Quotients for Two Application (maximum residue) of Flufenpyr-ethyl 

(broadcast) based on a Mallard duck NOAEC of 1040 ppm. 

11.8 

11.8 

SiteIApp. App. Rate Maximum Toxicity value Chronic RQ Food Items Method (lbs ai1A) EEC (ppm) (NOAEC) 

~0.01 

<0.01 

Short grass 11.80 1040 <0.01 

sugarcane 0.027 

(aerial) Tall grass 5.41 1040 <0.01 

Broadleaf plants I Insects 6.64 1040 <O.O 1 

Seeds 0.74 1040 cn nl 

The results indicate that for a broadcast application of flufenpyr-ethyl, there are no chronic LOC 

exceedances for birds. 

Section B: Summary of Risks to Aquatic Plants 

Page 18 

Flufenpyr-ethyl was shown to be moderately toxic to freshwater fish (LC,, = 2.5 - 3.75 ppm) and 

estuarinelmarine invertebrates (EC,, = 2.08 ppm) on an acute basis. However, the toxicity of 

flufenpyr-ethyl to freshwater invertebrates and estuarinelmarine fish was not seen at the solubility 

limit in aquatic environments (4.1 pprn in water). Based on the Tier I1 duckweed toxicity testing, 

the EC,, values of the parent flufenpyr-ethyl and its degradates S-3153 acid and S-3153-4-OH 

were 0.013,0.006, and >0.03 ppm, respectively. The Tier I1 non-vascular aquatic plants toxicity 
testing with the parent compound shows freshwater green alga (Selenastrum capricomutum) as 

the most sensitive non-vascular plant, with an EC,, of 0.009 ppm. Although chronic values were 

not determined for estuarinelmarine fish; freshwater early life stage and invertebrate life cycle 

values (NOAECILOAEC) were shown to be 0.4410.92 ppm and 0.4611.2 ppm, respectively, with 

significant reductions occurring in fish growth and invertebrate reproduction. In addition, the 

toxicity tests with aquatic organisms and plants, the solvent was used to maximize the chemical 

dissolution, exceeding EFED's guideline recommended range by l-fold. None of the aquatic 

organisms and plants were adversely affected by the solvent in these tests. 

Page 12 

Results from this risk assessment indicate that aquatic plants (vascular and non-vascular) are not 

likely to be exposed to parent flufenpyr-ethyl at levels of concern. No LOCs were exceeded for 

aquatic plants and potential risk is expected to be minimal for the parent compound, however, 

Ler~zna gihha results with the degradate S-3 153-acid produce an LOC exceedance for endangered 

species. No aquatic non-vascular plant studies with the degradates have been submitted to the 

Agency, therefore, risks to non-vascular plants are unknown. 

Page 19 

Estimates of Risks to Aquatic Organisms and Plants 

A means of integrating the results of exposure (EEC) and toxicity data is called the 

quotient method. For this method, risk quotients (RQs) are calculated by dividing exposure 

estimates by toxicity values, both acute and chronic. 

The toxicity test values (i.e., measurement endpoints) used in the acute and chronic risk 

quotients are derived from the results of required studies. The EEC, toxicity, and risk quotient 

values are provided below in Table 8. 

I Daphnia magna-Acute I >3 1 0.00028 

Table 8 - Toxicity, Exposure, and Risk Quotient Values of Flufenpyr-ethyl (based on two aeria 

0.027 lb aiIA, 10 days interval) 

Daphnia magna-Chronic I 1.2 0.00019 

I 

Species 

Rainbow trout-Acute 

I Rainbow trout--Early Life Stage I 0.92 I 0.OOOl 

Toxicity 

(PP~) 

2.5 

Exposure1 

(PP~) 

0.00028 

Estuarinelmarine fish- Acute 

Shrimp -Acute 

application of 

-- - 

>2.7 

2.08 I 0.00028 

Eastern Oyster--Shell deposition 

Risk Quotient 

(RQ) I 

0.00028 

>2 0.00028 
Aquatic Plants- Anabaena jlos-aquae I >0.05 1 0.00028 1 ~0.01 

surface water concentrations (EECs) are shown in ppm. 

Aquatic Plants-Duckweed (parent) 

Aquatic Plants-Duckweed (S3 153acid) 

-Soybean (MS) 

Aquatic Plants-Duckweed (S3153acrd) 

- Sugarcane (FL) 

Aquatic Plants-Duckweed (S3153acid) 

- Sugarcane (LA) 

Aquatic Plants-Duckweed (S3 15340H) 

Aquatic Plants- Selenastrum capricornutum 

Aquatic Plants- Navicula pelliculosa 

Aquatic Plants- Skeletonema costatum 

Risk Assessment Summary: 

As shown in table 8, no LOCs were exceeded for aquatic organisms exposed to parent 

flufenpyr-ethyl and aquatic plants exposed to parent flufenpyr-ethyl and S-3 153-4-08 degradate. 

Therefore, risks to fish, invertebrates, and aquatic plants from parent flufenpyr-ethyl are believed 

to be negligible. Also, since flufenpyr-ethyl is not persistent (half life - 7 days) in aquatic 

environments, exposure from this scenario based on GENEEC2 modeling with peak (acute) value 

of 0.3 ppb for parent flufenpyr-ethyl should not present a concern for any aquatic organisms from 

the proposed use sites of sugarcane and soybean since the toxicity values are at or greater than 

440 ppb. Importantly, LOCs were exceeded for aquatic vascular plants exposed to its degradate, 

S-3153-acid. However, exposure from same scenario as above based on PRZM-EXAM modeling 

with peak values of 0.6, 1.06, and 1.58 ppb for S-3 153-acid applied to sugarcane in Florida and 

Louisiana and soybeans in Missouri present a concern for aquatic plants. 

At the chronic level, reproductive effects and growth effects were identified in freshwater 

invertebrates and fish respectively. However, since the flow-through test maintains a constant 

concentration, it is not an accurate representation of what is expected to occur in the 

environment. The simulated aquatic exposure profile for each proposed use of flufenpyr-ethyl 

differs from the constant exposure in the flow-through test because of rapid degradation of parent 

flufenpyr-ethyl. The significance of the unrealistic constant concentration in the flow-through test 

is not completely clear. Since chronic effects to invertebrates and fish are not studied throughout 

the flow-through test, one cannot determine whether 21 or 60 days of exposure at the EC,dLC,, 

concentration were necessary to cause the effects, or if a shorter exposure at that parent 

concentration would sufice. Regardless, risk quotients did not exceed levels of concern. 

0.013 

0.006 

0.006 

0.006 

>0.03 

0.009 

0.16 

0.012 

0.00028 

0.000653 

0.00108 

0.00158 

0.0002 

0.00028 

0.00028 

0.00028 

0.02 

0.1 

0.18 

0.26 

<0.01 

0.03 

<0.01 

0.02 
Page 76 

Table B. Acute Risk Quotients for Aquatic Plants based upon Parent and Degradate Compounds. A Duckweed 

(Lemna gibba) EC,, of 0.01 3,0.006, and >0.03 ppm from Parent Flufenpyr-Ethyl and its Degradates, 

respectively, and a Nonvascular Plant (Skeletonema capricornutum) EC,, of 0.009 ppm from the Parent 

Compound. For Endangered Species, the L. gibba NOAEC of 0.00078, 0.0003, and 0.03 ppm from Parent 

Flufenpyr-Ethyl and its Degradates, Respectively. 

Site/ Application Endangered 

Method/ EGO (PP~) EEC NOAEC Species RQ Non-target plant 

Rate of Application Species Model (PP~) (ppm) (EEUNOAEC) RQ (EECIEC,,,) 

sugarcane/ aerial 1 duckweed GENEEC2 0.0 1 3 0.0003 0.00078 0.39 0.02 

0.027 (parent) 

soyhcan (MS) duckweed PRZM- 0.006 0.000653 0.0003 2.17 0.10 

(S1353 acid) EXAM 

sugarcane (LA) 

PRZM- 0.006 0.001 06 0.0003 -3.50 0.18 

EXAM 

PRZM- 0.006 0.00158 0.0003 5.30 0.26 

EXAM 

sugarcane I aerial duckweed GENEEC2 >0.03 0.00022 0.03 <0.01 <0.01 

(S135340H) 

sugarcane I aerial algae or diatom GENEEC2 0.009 0.0003 n/a n/a 0.03 

(parent) 

* exceeds the plant LOC for non-target or endangered plants (RQ 21) 

n/a - when information is not available or when a greater than toxicity value which minimal risk is presumed for the species. 

The endangered and non-target aquatic plants LOCs are not exceeded for vascular or nonvascular plants with the parent compound (S-3153) or S-3 153-4-OH. However, for testing with 

the S3153 acid, the endangered species LOC is exceeded but the non-target LOC is not exceeded 

for aquatic vascular plants for the proposed label uses on sugarcane, soybean, and field corn.