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OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

PC Code: 270000

DP Barcode: 424792

Date: May 4, 2015

MEMORANDUM

Subject: Isofetamid: Hazard Comparison Memo for Several Fungicides.

To: Cynthia Giles‐Parker, Chief

Tony Kish, Product Manager  

Fungicide Branch

Registration Division (7505P)

Office of Pesticide Programs

From: Rosanna Louie‐Juzwiak

Environmental Risk Branch 3

Environmental Fate and Effects Division (7507P)

Office of Pesticide Programs

Through: Dana Spatz, Chief

Environmental Risk Branch 3

Environmental Fate and Effects Division (7507P)

Office of Pesticide Programs

The purpose of this memorandum is to provide supporting information to the proposed decision

document and ecological risk assessment for the proposed Section 3 uses of the new chemical

isofetamid, on almond, lettuce, grapes (Subgroup 13‐07F), low growing berries (Subgroup 13‐07G),

rapeseed (Subgroup 20A), and turf. The ecological risk assessment identified the potential for chronic

risk to birds and mammals, acute risk to listed estuarine/marine invertebrates, and chronic risk to fish.

There is uncertainty about potential chronic risk to aquatic invertebrates because effects occurred at all

test concentrations, and there is a narrow margin between the lowest test concentration and the

estimated environmental concentrations. Toxicity to terrestrial invertebrates (i.e., honey bees) cannot

be assessed at this time due to the lack of data; therefore, there is uncertainty with the potential for risk

to these animals. In contrast, acute risk concerns were not identified for exposures to birds, mammals,

fish, freshwater invertebrates, non‐listed estuarine/marine invertebrates, or plants.   

The Biological and Economic Analysis Division (BEAD) identified several fungicides1 that may serve as

alternatives for the crop sites and pest spectrum on the proposed product labels. This analysis includes

the subset of fungicides (identified by the applicant) that can be replaced with an isofetamid application

1

USEPA, 2014, Selected Alternative Fungicides to Isofetamid Used on Almond, Grapes (and Crop Subgroup 13‐07F),

Low Growing Berries (Crop Subgroup 13‐07G), Turf Grass, Lettuce, and Rapeseed (Canola) [DP#421726]

for
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as part of a spray rotation schedule. This memorandum presents toxicity data for isofetamid and other

fungicides with respect to taxa that may be at risk as a result of the proposed uses of isofetamid. Tables

1 through 8 provide toxicity data on a chemical‐by‐chemical basis as they are available; chemicals are

generally ranked from the most to least sensitive endpoint.  It should be noted that lower toxicity values

represent fungicides that are more toxic on a hazard basis; however, this analysis does not consider

exposures from their registered uses.

Table 1.  Comparison of Mammalian (Norway rat, Rattus norvegicus) Chronic NOAECs for Isofetamid

and Other Fungicides

Chemical

(PC Code)

NOAEC

(mg a.i./kg‐diet) MRID

Boscalid

(128008) 100   45404906

Fluxapyroxad

(138009)   112   47923602

Iprodione

(109801) 150   42637801

Fluopyram

(080302) 200   47372441

Pyraclostrobin

(099100) 200 45596210

Penthiopyrad 680   47614906

47614907

Isofetamid  

(270000) 1,000   49011940

Table 2.  Comparison of Avian NOAEC Values for Isofetamid and Other Fungicides

Chemical

(PC Code) Organism NOAEC(mg a.i./kg‐diet) MRID

Fluopyram

(080302)

Bobwhite quail

Colinus virginianus 46.7   47372344

Fluxapyroxad

(138009)

Bobwhite quail

Colinus virginianus <100   47923720

Isofetamid

(270000)

Bobwhite quail

Colinus virginianus 276   49018423

Boscalid

(128008)

Bobwhite quail

Colinus virginianus 300   45404925

Iprodione

(109801)

Bobwhite quail

Colinus virginianus 300   00099126

Pyraclostrobin

(099100)

Mallard duck

Anas platyrhynchos 1,061.5 45118427

Penthiopyrad

(090112)

Mallard duck

Anas platyrhynchos 1520   47614983

Bobwhite quail

Colinus virginianus 5090   47614982
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Table 3. Comparison of Honey Bee Acute Contact and Oral Values for Isofetamid and Other Fungicides

Chemical(PC Code)

Contact LC50

(ug a.i./bee, unless noted)

Oral LD50

(ug a.i./bee, unless noted) MRID

Iprodione(109801) N/A N/A N/APyraclostrobin(099100)

TGAI: > 100

TEP (with boscalid): >32.9

TGAI: >110

TEP (with metconazole): 2.7

TGAI: 45118711

TEP (with boscalid): 48470202TEP (with metconazole): 47445

Fluxapyroxad(138009)

TGAI: > 100

TEP: 15.7

(BAS 700 01 F, with pyraclostrobin)

TGAI: > 111

TEP: > 32.4

(BAS 703 02 F)

TGAI: 47923748BAS 700 01 F: 48565301

BAS 703 02 F: 47924317

Penthiopyrad(090112)

TGAI: > 500

TEP (Fontelis): 23.5 (96‐hours)

TGAI: > 500

TEP (Fontelis): 50.7 (96‐hours)

TGAI: 47615016/‐17TEP: 47615237

Isofetamid(270000)

TGAI: 100

TEP: >100

TGAI: > 30

TEP: >100

TGAI: 49018426TEP: 49018425

Fluopyram(080302)

TGAI: >100 ug test material

TEP: >83.2

TGAI: > 102.3 ug test material

TEP: > 89

TGAI: 47372347TEP: 47372348

Boscalid(128008) > 200 ug/bee > 166 ug/bee 45405019

N/A = Data Not Available

Table 4. Estuarine/marine invertebrate Acute Toxicity values for Isofetamid and Other Fungicides

Chemical(PC Code) Organism EC50/IC50/LC50 (mg a.i./L, unless noted) MRIDFluxapyroxad(138009)

Eastern oyster

Crassostrea virginica IC50 = 0.96 47923762

Pyraclostrobin(099100)

Saltwater mysid

Americamysis bahia LC50: 0.00416 45118412

Fluopyram(080302)

Saltwater mysid

Americamysis bahia > 0.51 47372327

Boscalid(128008)

Eastern oyster

Crassostrea virginica 1.02 45405003

Penthiopyrad(090112)

Eastern oyster

Crassostrea virginica 1.2 47615033
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Chemical(PC Code) Organism EC50/IC50/LC50 (mg a.i./L, unless noted) MRIDIsofetamid(270000)

Saltwater mysid

Americamysis bahia LC50: 1.51 49011998

Iprodione(109801)

Eastern oyster

Crassostrea virginica 2.3 40489202

Table 5. Freshwater Fish Chronic Toxicity Values for Isofetamid and Other Fungicides

Chemical(PC Code) Organism LOAEC (mg a.i./L) NOAEC (mg a.i./L) MRIDPyraclostrobin(099100)

Rainbow Trout

Oncorhynchus mykiss 0.00642 0.00235 45118421

Fluxapyroxad(138009)

Carp

Cyprinus carpio

0.042

(ACR)

0.022

(ACR)

ACR based on

4792372447923729

Isofetamid(270000)

Fathead minnow

Pimephales promelas 0.18 0.086 49018406

Penthiopyrad(090112)

Fathead minnow

Pimephales promelas 0.188 0.100 47614994

Boscalid(128008)

Rainbow Trout

Oncorhynchus mykiss 0.241 0.116 45405006

Fluopyram(080302)

Fathead minnow

Pimephales promelas 0.269 0.135 47372336

Iprodione(109801)

Fathead minnow

Pimephales promelas ‐‐  0.26 40550801

ACR = acute‐to‐chronic ratio

N/A = Data Not Available

Table 6. Freshwater Invertebrate Chronic Toxicity Values for Isofetamid and Other Fungicides

Chemical

(PC Code) Organism LOAEC (mg a.i./L) NOAEC (mg a.i./L) MRID

Iprodione

(109801) N/A N/A N/A N/A
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Chemical

(PC Code) Organism LOAEC (mg a.i./L) NOAEC (mg a.i./L) MRID

Pyraclostrobin(099100)

Water flea

Daphnia magna

0.008 0.004 45118419

Penthiopyrad(090112)

Water flea

Daphnia magna

TGAI: 0.818

TEP: 0.02075

TGAI: 0.471

TEP: 0.1061

TGAI: 47615003

TEP: 47615236

Boscalid(128008)

Freshwater amphipod

Hyalella azteca

> 1.066 0.298 45405009

Isofetamid(270000)

Water flea

Daphnia magna 0.39 <0.39 L 49018405

Fluxapyroxad(138009)

Water flea

Daphnia magna

0.95 0.46 47923736

Fluopyram(080302)

Water flea

Daphnia magna

2.99 1.21 47372334

N/A = Data Not Available

Table 7. Estuarine/marine Fish Toxicity values for Isofetamid and Other Fungicides

Chemical(PC Code) Organism LOAEC (mg a.i./L) NOAEC (mg a.i./L) MRIDBoscalid(128008) N/A N/A N/A N/AFluopyram(080302) N/A N/A N/A N/AFluxapyroxad(138009) N/A N/A N/A N/AIprodione(109801) N/A N/A N/A N/APenthiopyrad(090112)

Sheepshead minnow

Cyprinodon variegates 0.897 0.476

ACR based on

476149884761499447615034
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Chemical(PC Code) Organism LOAEC (mg a.i./L) NOAEC (mg a.i./L) MRIDIsofetamid(270000)

Fathead minnow

Pimephales promelas 0.181 0.0861 490184061

Pyraclostrobin(099100)

Sheepshead minnow

Cyprinodon variegates 0.024 0.0108 45420101

1 The freshwater fish data were used to assess estuarine/marine fish for isofetamid.

ACR = acute‐to‐chronic ratio

N/A = Data Not Available

Table 8. Estuarine/marine Invertebrate Toxicity values for Isofetamid and Other Fungicides

Chemical

(PC Code) Organism LOAEC (mg a.i./L) NOAEC (mg a.i./L) MRID

Boscalid(128008) N/A N/A N/A N/AFluopyram(080302) N/A N/A N/A N/AFluxapyroxad(138009) N/A N/A N/A N/AIsofetamid(270000) N/A N/A N/A N/APyraclostrobin(099100)

Saltwater mysid

Americamysis bahia 0.00093 0.0005 46227601

Iprodione(109801)

Saltwater mysid

Americamysis bahia ‐‐  0.0035 40832201

Penthiopyrad(090112)

Eastern Oyster

Crassostrea virginica 0.388 0.223

ACR based on

476149964761500347615033

ACR = acute‐to‐chronic ratio

N/A = Data Not Available