2  41 birds and 7 reptiles that may consume bul bs (no listed terrestrial-phase amphibians were identified) 1

 28 birds that consume seeds (no listed rept iles or terrestrial-phase amphibians were identified)

 33 mammals that consume seeds

 59 terrestrial invertebrates (non-subterranean species)

The MA finding for direct effects to birds, re ptiles, and mammals is based on exceedance of the listed species LOC for specific food items (treated seed and bulbs). The finding for potential
direct effects to terrestrial invertebrates is base d on insufficient data; expo sure values are greater than the non-definitive endpoint (no effects observed) obtained in the available toxicity study. Thus, the magnitude of any potential effects to terrestrial invertebra tes, if any, cannot be quantified. The MA finding is also based on the assumption that the geographic range of a listed species overlaps with the action area and that i ndividuals may visit the treatment area. A NE determination is concluded for the 17 listed terrestrial invertebrate species categorized as subterraneous. In general, these species are un likely to be exposed to labeled applications of denatonium saccharide because they are adap ted to living in caves or similar underground
habitats.

The MA finding for indirect effects is limited to listed birds, reptil es, terrestrial-phase amphibians, mammals, terrestrial insects, and plants (terrestrial and aquati c vascular) that have an obligate relationship with a species that is di rectly affected by denatonium saccharide. A NE
determination is concluded for indirect eff ects to listed species not having an obligate relationship with a species direct ly affected by denatonium sacchar ide due to the highly localized and short-term nature of any effects.

A NLAA determination has been made for bot h direct and indirect effects because the probability of a listed species encountering areas of treatment is expected to be highly unlikely. This finding is based on the extremely limited use of denatonium saccharide (about 100 pounds is sold annually nationwide) a nd the nature of the use. Ther e is no expectation that large contiguous areas of treatment will o ccur, rather use is expected to result in very small treatment areas (less than a typical reside ntial yard) scattered across the la ndscape with few treatment areas occurring anywhere simultaneousl y. Given the combination of wi dely dispersed and limited use, it is highly unlikely that individuals of a liste d species will encounter areas of treatment. Therefore, risk is expected to be discountab le because potential exposur e will be confined to small patches isolated in space a nd time. EPA asks for concurrence on this conclusion from the U.S. Fish and Wildlife Service (FWS).

The EFED endangered species knowledge database was used to identify li sted species included in the NLAA determination for direct effects ( Tables 1-3 ). The NLAA determination was made only for species identified in the database as e ither seed consumers (birds, reptiles, terrestrialphase amphibians, and mammals) or bulb consum ers (birds, reptiles, and terrestrial-phase amphibians). Bulbs are not specif ically included as a food item in the database. This does not mean that there are no listed bird, reptile, or te rrestrial-phase amphibian species that eat bulbs,
rather that bulbs were not an identified food item. It was conservatively assumed that species

1 Includes 28 avian species that consume seeds3 that eat plant material (nectar was excluded) ma y eat bulbs if available. Furthermore, some species may grub for bulbs while others may only opportunistically consume bulbs brought to the surface and discarded by another animal. Body weight was not used to exclude any animals included in the NLAA determination because the pot ential risk concern was for all assessed size
classes of birds and mammals. The NLAA dete rmination for terrestrial insects was for nonsubterraneous species. The database does not current ly include attributes for terrestrial insects; therefore, this assessment relie s on a recent preliminary risk a ssessment on silica (USEPA, 2013) for identifying and excluding listed species categorized as subterraneous dwellers.

Table 1. Listed Mammals that Consume Seeds

Common name Scientific name

Alabama beach mouse Peromyscus polionotus ammobates Amargosa vole Microtus californicus scirpensis

Anastasia Island beach mouse Peromyscus polionotus phasma Carolina northern flying squirrel Glaucomys sabrinus coloratus

Choctawhatchee beach mouse Peromyscus polionotus allophrys Delmarva Peninsula fox squirrel Sciurus niger cinereus

Florida salt marsh vole Microtus pennsylvanicus dukecampbelli Fresno kangaroo rat Dipodomys nitratoides exilis Giant kangaroo rat Dipodomys ingens Grizzly bear Ursus arctos horribilis Key Largo cotton mouse Peromyscus gossypinus allapaticola Key Largo woodrat Neotoma floridana smalli

Little Mariana fruit Bat Pteropus tokudae

Louisiana black bear Ursus americanus luteolus Mariana fruit Bat (=Mariana flying fox) Pteropus mariannus mariannus Morro Bay kangaroo rat Dipodomys heermanni morroensis Mount Graham red squirrel Tamiasciurus hudsonicus grahamensis Northern Idaho ground squirrel Spermophilus brunneus brunneus Pacific pocket mouse Perognathus longimembris pacificus Perdido Key beach mouse Peromyscus polionotus trissyllepsis Preble's meadow jumping mouse Zapus hudsonius preblei Riparian brush rabbit Sylvilagus bachmani riparius

Salt marsh harvest mouse Reithrodontomys raviventris San Bernardino Merriam's kangaroo rat Dipodomys merriami parvus San Miguel Island Fox Urocyon littoralis littoralis

Santa Catalina Island Fox Urocyon littoralis catalinae

Santa Cruz Island Fox Urocyon littoralis santacruzae

Santa Rosa Island Fox Urocyon littoralis santarosae

Southeastern beach mouse Peromyscus polionotus niveiventris Stephens' kangaroo rat Dipodomys stephensi (incl. D. cascus) Tipton kangaroo rat Dipodomys nitratoides nitratoides Utah prairie dog Cynomys parvidens Virginia northern flying Squirrel Glaucomys sabrinus fuscus4 Table 2. Listed Birds that Consume Seed s and Listed Birds a nd Reptiles that May
Consume Bulbs

Common name Scientific name Taxa Food Source

Seeds Bulbs Akiapola`au (honeycreeper) Hemignathus munroi Birds XAttwater's greater prairiechicken Tympanuchus cupido

attwateri Birds X

Blunt-nosed leopard lizard Gambelia silus Reptiles X Bridled white-eye Zosterops conspicillatus conspicillatus Birds X

Cape Sable seaside sparrow Ammodramus maritimus
mirabilis Birds X

Coachella Valley fringe-toed
lizard Uma inornata Reptiles X

Coastal California gnatcatcher Polioptila californica californica Birds X X

Culebra Island giant anole Anolis roosevelti Reptiles X

Desert tortoise Gopherus agassizii Reptiles X Florida grasshopper sparrow Ammodramus savannarum floridanus Birds X

Florida scrub jay Aphelocoma coerulescens Birds X X Gopher tortoise Gopherus polyphemus Reptiles X

Guam rail Rallus owstoni Birds X X Hawaii akepa (honeycreeper) Loxops coccineus coccineus Birds X Hawaiian (='alala) Crow Corvus hawaiiensis Birds X X Hawaiian (=koloa) Duck Anas wyvilliana Birds X X

Hawaiian common moorhen Gallinula chloropus
sandvicensis Birds X X

Hawaiian goose Branta (=Nesochen)
sandvicensis Birds X X

Inyo California towhee Pipilo crissalis eremophilus Birds X X Island night lizard Xantusia riversiana Reptiles X Ivory-billed woodpecker Campephilus principalis Birds X X Kauai `o`o (honeyeater) Moho braccatus Birds X Kauai akialoa (honeycreeper) Hemignathus procerus Birds X Kauai creeper Oreomystis bairdi Birds X X Kirtland's warbler (=wood) Dendroica kirtlandii Birds X Large Kauai (=kamao) Thrush Myadestes myadestinus Birds X X Laysan duck Anas laysanensis Birds X X Laysan finch (honeycreeper) Telespyza cantans Birds X X

Mariana common moorhen Gallinula chloropus guami Birds X Mariana (=aga) Crow Corvus kubaryi Birds X Masked bobwhite (quail) Colinus virginianus ridgwayi Birds X X Micronesian megapode Megapodius laperouse Birds X5 Common name Scientific name Taxa Food Source

Seeds Bulbs Mississippi sandhill crane Grus canadensis pulla Birds X X

Molokai thrush Myadestes lanaiensis rutha Birds X Mona ground Iguana Cyclura cornuta stejnegeri Reptiles X Nihoa finch (honeycreeper) Telespyza ultima Birds X Nukupu`u (honeycreeper) Hemignathus lucidus Birds X Palila (honeycreeper) Loxioides bailleui Birds X X Puerto Rican parrot Amazona vittata Birds X X Puerto Rican plain Pigeon Columba inornata wetmorei Birds X X Red-cockaded woodpecker Picoides borealis Birds X X Rota bridled White-eye Zosterops rotensis Birds X X San Clemente sage sparrow Amphispiza belli clementeae Birds X X Small Kauai (=puaiohi) Thrush Myadestes palmeri Birds X Spectacled eider Somateria fischeri Birds X X Whooping crane Grus americana Birds X

Yellow-shouldered blackbird Agelaius xanthomus Birds X `O`u (honeycreeper) Psittirostra psittacea Birds X

Table 3. Listed Terrestrial Insects (non-subterraneous)

Common name Scientific name Taxa American burying beetle Nicrophorus americanus Insect

Ash Meadows naucorid Ambrysus amargosus Insect Bay checkerspot butterfly Euphydryas editha bayensis Insect Behren's silverspot butterfly Speyeria zerene behrensii Insect Blackburn's sphinx moth Manduca blackburni Insect Callippe silverspot butterfly Speyeria callippe callippe Insect Carson wandering skipper Pseudocopaeodes eunus obscurus Insect Caseys June Beetle Dinacoma caseyi Insect Comal Springs dryopid beetle Stygoparnus comalensis Insect Comal Springs riffle beetle Heterelmis comalensis Insect Delhi Sands flower-loving fly Rhaphiomidas terminatus abdominalis Insect Delta green ground beetle Elaphrus viridis Insect El Segundo blue butterfly Euphilotes battoides allyni Insect Fender's blue butterfly Icaricia icarioides fenderi Insect Florida leafwing butterfly Anaea troglodyta floridalis Insect Flying earwig Hawaiian damselfly Megalagrion nesiotes Insect Hawaiian picture-wing fly Drosophila digressa Insect Hine's emerald dragonfly Somatochlora hineana Insect Hungerford's crawling water Beetle Brychius hungerfordi Insect Karner blue butterfly Lycaeides melissa samuelis Insect Kauai cave wolf or pe'e pe'e maka 'ole spider Adelocosa anops Arachnid

Kern primrose sphinx moth Euproserpinus euterpe Insect6 Common name Scientific name Taxa Laguna Mountains skipper Pyrgus ruralis lagunae Insect Lange's metalmark butterfly Apodemia mormo langei Insect Lotis blue butterfly Lycaeides argyrognomon lotis Insect Mission blue butterfly Icaricia icarioides missionensis Insect Mitchell's satyr Butterfly Neonympha mitchellii mitchellii Insect Mount Charleston blue butterfly Plebejus shasta charestonensis Insect Myrtle's silverspot butterfly Speyeria zerene myrtleae Insect Northeastern beach tiger beetle Cicindela dorsalis dorsalis Insect Ohlone tiger beetle Cicindela ohlone Insect Oregon silverspot butterfly Speyeria zerene hippolyta Insect Pacific Hawaiian damselfly Megalagrion pacificum Insect Palos Verdes blue butterfly Glaucopsyche lygdamus palosverdesensis Insect

Pawnee montane skipper Hesperia leonardus montana Insect Puritan tiger beetle Cicindela puritana Insect Quino checkerspot butterfly Euphydryas editha quino (=E. e. wrighti) Insect

Saint Francis' satyr butterfly Neonympha mitchellii francisci Insect Salt Creek Tiger beetle Cicindela nevadica lincolniana Insect San Bruno elfin butterfly Callophrys mossii bayensis Insect Schaus swallowtail butterfly Heraclides aristodemus ponceanus Insect Smith's blue butterfly Euphilotes enoptes smithi Insect Spruce-fir moss spider Microhexura montivaga Arachnid Taylor's Checkerspot butterfly Euphydryas editha taylori Insect Uncompahgre fritillary butterfly Boloria acrocnema Insect Valley elderberry longhorn beetle Desmocerus californicus dimorphus Insect Zayante band-winged grasshopper Trimerotropis infantilis Insect [Unnamed] pomace fly Drosophila aglaia Insect [Unnamed] pomace fly Drosophila differens Insect [Unnamed] pomace fly Drosophila hemipeza Insect [Unnamed] pomace fly Drosophila heteroneura Insect [Unnamed] pomace fly Drosophila montgomeryi Insect [Unnamed] pomace fly Drosophila mulli Insect [Unnamed] pomace fly Drosophila musaphila Insect [Unnamed] pomace fly Drosophila neoclavisetae Insect [Unnamed] pomace fly Drosophila obatai Insect [Unnamed] pomace fly Drosophila ochrobasis Insect [Unnamed] pomace fly Drosophila substenoptera Insect [Unnamed] pomace fly Drosophila tarphytrichia Insect

References

USEPA, 2013. Environmental Fate and Ecol ogical Effects Risk Assessment for the Registration Review of Silica (DP 393658)

## REGISTRATION REVIEW

ECOLOGICAL RISK ASSE SSMENT AND
EFFECTS DETERMINATIO N



# Denatonium saccharide

CAS Number : 90823

- 38

- 4

PC Code : 129045

Prepared by:

Michael Lowit, Ph.D., Ecologist He Zhong, Ph.D., Biologist
Environmental Risk Branch 1

Reviewed by: Edward Odenkirchen, Ph.D., Senior Science Advisor Stephen Wente, Ph.D., Biologist Sujatha Sankula, Ph.D., Branch Chief
Environmental Risk Branch 1
Environmental Fate and Effects Division U. S. Environmental Protection Agency Office of Pesticide Programs
Environmental Fate and Effects Division
Environmental Risk Branch I 1200 Pennsylvania Ave., NW
Mail Code 7507P Washington, DC 204602 I. Executive Summary

Denatonium saccharide , registered by MCB, LLC, is a bittering agent used as a squirrel, vole, dog, and cat repellant on outdoor structures and surfaces applied with a coarse droplet sprayer or
with a brush . It may also be applied to seeds and bulbs. Ther e is currently one registered product, RO

- PEL (Reg. No. 8117

- 1), a ready

- to

- use liquid formulation which contains 0.065% denatonium saccharide. Currently, only 50 Kg per annum or less of denatonium saccharide is imported (Email correspondence from the regi strant, Roger Brown, MCB, LLC, to Andrea Mojica, EPA, 10/8/2012). There are no restrictions on application rates; however, 1 gallon of

RO

- PEL treats 1000 to 4000 ft 2 and a second application may be made after 2

- 7 days. Although not explicitly stated on t he product label

, the Biological and Economic Analysis Division (BEAD) states that the product appear s to be used only in residential settings , either by
homeowners or comme rcial contractors (USEPA, 2013)

.

No previous risk assessments have been conducted for denatonium saccharide. Toxicity and fate data were recommended in the problem formulation ( USEPA, 2008 ) 1 and a data call in (DCI)
was issued for those studies on January 29, 2010 . Subsequently, the registrant submitted a data waiver request for those studies and EFED recommended against waiving the studies (USEPA, 2011) ; however , no new data have been submitted. Only o ne

- registrant submitted toxicity study is available for denatonium saccharide. An acute oral toxicity study with the rat showed an LD 50 > 5000 mg formulation /kg

- bw (> 3.25 mg denatonium saccharide/kg

- bw ) . No fate data are available. An open literature search did not yield any toxicity data for denatonium saccharide. Analog chemicals have not been identified ( http://aim.epa.gov/ ); however, limited data are available for denatonium benzoate, which shares the same denatonium cation with denatonium
saccharide. Denatonium benzoate is a bittering agent like denatonium saccharide

. Denatonium
benzoate toxic ity was used as a surrogate for denatonium saccharide

, given that it is the best available information. The denatonium cation was assumed to be primarily responsible for denatonium saccharide toxicity. Saccharine (sodium saccharide) is an artificial sweetener used in many foods. T he risk characterization of denatonium saccharide was based on denatonium cation toxicity and exposure. T he risk characterization is qualitative (i.e., RQs were not calculated) given the inherent uncertainty in using the de natonium benzoate data.

There is a n acute risk concern for listed and non

- listed birds (surrogates for reptiles and
terrestrial

- phase amphibians) from use on seeds and bulbs. One possible option to reduce or
eliminate the risk concern for birds is thro ugh label changes such as removal of seed and bulb

use or changes to the application rates, althoug h this may be impractical given reliance on the
end

- user to treat the seeds and bulbs

. Risk could not be assessed for bees visiting flowers that develop fro m treated seeds, treated bulbs

, and plants that take up denatonium saccharide used to treat structures (run

- off or spray drift exposure ) because the only known toxicity study with bees
resulted in a non

- definitive endpoint at a test concentration that is lower than exposure estimates

. Risk to bees could be assessed with denatonium saccharide toxicity data (adult and larval oral) that tests at a higher test concentration or with a refined exposure estimate based on denatonium

1 (850.2100) Avian acute oral toxicity, (850.2200) Avian dietary toxicity, (850.1010) Aquatic invertebrate acute toxicity, (850.1075) Freshwater fish acute toxicity test, (835.2120) Hydrolysis, (835.4100) Aerobic soil metabolism, and (835.1230) Sediment a nd soil adsorption/desorption3 saccharide residue data for l abeled use rates. Furthermore, risk would be negligible if information is available that indicates that denatonium saccharide is not transported into plant material, although this seems unlikely given that it is water soluble and has a low K
ow . There is

a potential acute risk concern for listed mammals ; however the concern is limited to use on some types of seeds (there is not a concern for six of the seven evaluated grass species)

. Possible options for reducing risk to listed mammals would be label chan ges such as requiring seed incorporation or lowering the maximum application rate for seed use in areas where listed mammals that eat seeds may be present

. Although direct effects are expected for listed and non

listed species, indirect risks to non

- liste d species are expected to be limited to obligate relationships given the small scale use of the product. Denatonium saccharide does not universally deter all organisms; thus, t he risk concern for direct effects to birds and mammals is
limited to animals t hat are not deterred by denatonium saccharide. The degree to which this may be the case for any given species cannot be addressed with the available information. Large margins of safety (low exposure compared to estimated toxicity) suggest little risk fo r aquatic organisms. Risk to terrestrial plants is assumed low given the low risk to aquatic plants. Chronic risk to aquatic and terrestrial organisms is assumed to be negligible given the limited
and localized use of denatonium saccharide

.

Table 1

. Summary of Direct and Indirect Effects Associated with Registered Uses of
Denatonium Saccharide

Taxon Risk Concern for
Direct Effects? Risk Concern for
Indirect Effects to

Listed Species? Non

- Listed Listed Birds, reptiles, and terrestrial

- phase amphibians Yes Yes Yes 1

Mammals No Yes Yes 1

Terrestrial invertebrates (honeybees) 2 Unknown 3 NA Unknown 3
Terrestrial (upland and semi

- aquatic) plants

– monocots No No Yes 1
Terrestrial (upland and semi

- aquatic) plants

– dicots No No Yes 1

Freshwater fish and aquatic

- phase amphibians No No No

Marine/estuarine fish No No No

Freshwater crustaceans No No No

Mollusks No No No

Marine/estuarine crustaceans No No No Aquatic vascular plants No No Yes 1
Aquatic non

- vascular plants No No No

1 Indirect effect as a result of direct effects to birds or mammals are expected only if a species has an

obligate/dependent relationship with a bird or mammal given the limited use pattern.

2 Honeybee LOC = 0.4 and is used as a surrogate for terrestrial invertebrates. Cur rently there is not an LOC for

listed terrestrial invertebrates.

3 The only known toxicity study with bees resulted in a non

- definitive endpoint at a test concentration that is lower

than exposure estimates. NA = Not applicable

II. Use Characterization and Methods of Application

The RO

- PEL product label allows application to outdoor structures and surfaces such as trees, fences, poles, decks, planters, siding, garbage cans, and furniture. There are no restrictions on the application e quipment except that the sprayer should be able to deliver a coarse droplet size and that mist blowers and ultra low volume sprayer are prohibited. It is assumed that hand

- held sprayers are the most likely spray equipment given the assumed residential use

. The application4 rate for this use is 1 gallon per 1,000 to 4,000 ft 2 . A second application is permitted after 2

- 7 days. There are no annual limits. This product is also labeled as a bulb and seed treatment to reduce consumption and damage by tree squ irrels and voles. The directions for these uses only state "Using rubber gloves, place seeds or bulbs in a plastic or metal container and spray thoroughly until soaked." No further application information is provided on the label. Based on
extension servic e and trade organization information, as well as best professional judgment,

BEAD provided application rate estimates for seeds ( ranging from 2.3 x 10 - 4 to 2.6 x 10 - 3 lb
ai/1000 ft 2 for seven common grass species ) and bulbs (6 x 10 - 6 lb ai/bulb) (USEPA, 20 13)

.

III. Summary of Environmental Fate

Denatonium saccharide is formed by the ionic bond between two oppositely charged ions (denatonium and saccharide). The denatonium chemical and physical properties and the
saccharide structure are summarized in Table 2

.

No chemical or physical property da ta for denatonium saccharide have been submitted. The Agency recommended hydrolysis (835.2120), aerobic soil metabolism (835.4100), and adsorption/desorption (835.1230) studies in the problem formulation (USEPA, 2008). In addition, EFED did not concur wi th the data waiver requests for the above studies (USEPA, 2011). Because of these unfulfilled data gaps, the Agency used EPI v4.10 to estimate the chemical and physical propert ies of the denatonium cation , which was assumed to be primarily responsible for denatonium saccharide toxicity

.

The Koc value estimated by the EPI v 4.10 may not be appropriate for the denatonium cat ion as its leaching behavior is regulated by soil pH and not by soil organic carbon content. Therefore, the Kd value is likely better suited to predict the leaching potential of the denatonium cation

. The denatonium benzoate Kd value is used as a surrogate for denatonium saccharide b ecause the
Kd for the denatonium cation is not available. The denatonium benzoate Kd value was obtained from a submitted study (MRID 47146904).

Table 2 . Denatonium Physical and Chemical Properties and Saccharide Structure

Parameter Value Reference

Denatonium Saccharide

Chemical Name benzyl

- [2

- (2,6

- dimethylanilino)

- 2

- oxoethyl]

- diethylazanium;1,1

- dioxo

- 1,

2

- benzothiazol

- 3

- olate NCBI 1

Empirical Formula C 28 H 33 N 3 O 4 S

Molecular mass 507.64

CAS Number 90823

- 38

- 4

Structure Sigma 2

Denatonium

Empirical Formula C 21 H 29 N 2 O 1

SMILES c1ccccc1CN(CC)(CC)CC(=O)Nc2c(C)ccc

c2C5 Parameter Value Reference

Molecular mass 325.48 EPI V4.10
Solubility (25°C) 428.9 mg/L

Log Kow 0 .18 IUPAC 3

Vapor pressure (23.1°C) 3.57 x 10 - 13 mm Hg EPI V4.10
Henry’s law constant (20°C, pH 7) 1.21 x10 - 18 atm·m 3 /mol
Hydrolysis (t 1⁄2 ) Stable No Data
Aqueous Photolysis (t 1⁄2 ) Stable
Aerobic Aquatic Metabolism (t 1⁄2 ) 37.5 days EPI V4.10

Aerobic Soil Metabolism (t 1⁄2 ) 75 days

Anaerobic Soil Metabolism (t 1⁄2 ) 338 days
Kd (ml/g) Boghall sandy loam 7.9 Easter Howgate Sand 11.4 Kitleyknowe sandy loam 20.8 Balmanno silty clay loam 527.8 MRID 47146904 (a denatonium benzoate study)

Saccharide

SMILES (Saccharide) C1=CC=C2C(=C1)C(

- NS2(=O)=O)=O
Empirical Formula (Saccharide) C 7 H 4 N 1 O 3 S 1
Molecular mass 182 .18

1 http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=64772

2 http://www.sigmaaldrich.com/catalog/product/sigma/d2418?lang=en®ion=US

3 The IUPAC website ( http://sitem.herts.ac.uk/aeru/iupac/1398.htm ) reports log Kow = 0.18 for denatonium
benzoate

.

IV. Summary of Ecological Effects

One

- registrant submitted toxicity study is available for denatonium saccharide. An acute oral toxicity study with th e rat showed an LD 50 > 5000 mg formulation/kg

- bw (> 3.25 mg denatonium saccharide/kg

- bw ). An open literature search did not yield any toxicity data for denatonium saccharide. Analog chemicals have not been identified ( ht tp://aim.epa.gov/ ); however, limited data are available for denatonium benzoate, which shares the same denatonium
cation with denatonium saccharide. Denatonium benzoate toxicity was used as a surrogate for denatonium saccharide given that it is the best a vailable information (including acute oral toxicity to rats). Risk to mammals could not be assessed using the submitted denatonium
saccharide data because of the lack of mortality at the limit test concentration which is lower
than estimated environmental concentrations (EECs) ; therefore, submitted denatonium benzoate
data was used to better characterize risk to mammals. Registrant submitted toxicity studies are
summarized in Table 3 ; additional details about those studies and other toxicity information are
discussed below. Denatonium benzoate toxicity is presented in this section

, but the risk
assessment consider s toxicity of and exposure to the denatonium cation. This was calculat ed by multiplying the denatonium benzoate toxicity by the molecular weight ratio of denatonium (325.48) to denatonium benzoate (446.59). Exposure expressed as the denatonium cation was calculated by multiplying the denatonium saccharide exposure by the mo lecular weight ratio of denatonium (325.48) to denatonium saccharide (507.64).6 Table 3. Summary of Toxicity of Denatonium Saccharide and Denatonium Benzoate (Registrant Submitted Studies) 1

Test Species Exposure
Scenario Summary MRID

Denatonium Saccharide

Rat Single oral
dose LD 50 > 5000 mg formulation/kg

- bw

LD 50 > 3.25 mg denatonium saccharide/kg

- bw

No effects observed 43698107

Denatonium Benzoate

Northern bobwhite quail ( Colinus virginianus ) Single oral
dose LD 50 = 196 mg ai/kg

- bw (95% C.I. 145

- 264) NOAEL = 50 mg ai/kg

- bw LOAEL = 100 mg ai/kg

- bw

Endpoints affected: mortality and clinical signs of toxicity 47146905

11 days (5 day exposure) LC 50 = 5080 mg ai/kg diet (95% C.I. 2520 to + infinity) NOAEC < 657 mg ai/kg diet LOAEC = 657 mg ai/kg diet

Endpoint affected: mortality 47146906

Mallard duck ( Anas platyrhynchos ) 8 days (5 day exposure) LC 50 > 5150 mg ai/kg diet NOAEC = 5150 mg ai/kg diet LOAEC > 5150 mg ai/kg diet

No effects observed 47146907

Rat Single oral
dose LD 50 = 648 mg ai/kg

- bw (95% C.I. 506

- 832) (female)

LD 50 = 841 mg ai/kg

- bw (95% C.I. 707

- 1000) (male) NOAEL < 500 mg ai/kg

- bw

Endpoints affected: mortality and clinical signs of toxicity 47135802

Rainbow trout ( Salmo gairdneri ) 96 hr static LC 50 > 1000 mg/L* NOAEC = 500 mg/L LOAEC = 1000 mg/L

Endpoints affected: mortality and sublethal effects

*There is uncertainty about the test material and test concentration in terms of active ingredient (denatonium benzoate). 47135816

Crangon sp. 96 hr static LC 50 = 554 mg/L (95% C.I. 412

- 755)* NOAEC = 125 mg/L LOAEC = 250 mg/L

Endpoint affected: mortality

*There is uncertainty about the test material and test concentration in terms of active ingredient (denatonium benzoate). 471358 177 Test Species Exposure
Scenario Summary MRID

Water flea (Daphnia magna) 48 hr EC 50 = 10.2 mg/L (95% C.I. 7.7

- 14.0) (nominal) NOAEC = 5 mg/L LOAEC = 10 mg/L

Endpoints affected: mortality

47135818

21 day
static renewal Parental survival NOAEC = 2 mg/L (nominal) LOAEC = 5 mg/L

Reproduction (brood release and offspring per parent) NOAEC ≥ 5 mg/L LOAEC > 5 mg/L

Freshwater

diatom (Nitzschia

palea) 70.5 hr Yield (0

- 70.5 hr)

IC 50 = 5.0 to 10.0 mg/L (nominal) NOAEC = 5.0 mg/L LOAEC = 10 mg/L

Growth Rate (0

- 45.5 hr)

IC 50 = 6.1 mg/L (95% C.I. 5.8

- 6.5) NOAEC = 5.0 mg/L LOAEC = 10 mg/L

Area Under the Growth Curve (0

- 70.5 hr)

IC 50 = 5.7 mg/L (95% C.I. 5.2

- 6.3) NOAEC = 5.0 mg/L LOAEC = 10 mg/L 47135819

1 The risk assessment considers toxicity of the denatonium cation. Toxicity in Table 3 is presented in terms of denatonium saccharide and denatonium benzoate. Toxicity as the denatonium cation is calculated by multiply toxicity of denatonium saccharide an d denatonium benzoate by the molecular weight ratio of denatonium (325.48) to denatonium saccharide (507.64) and denatonium (325.48) to denatonium benzoate (446.59), respectively.

Denatonium Saccharide Data

Acute Oral Toxicity to Rats

The acute oral LD 50 was > 5000 mg formulation/kg

- bw (> 3.25 mg denatonium saccharide/kg

bw ) (MRID 43698107 ) for rats. No effects were observed.

Ancillary Information

A study report on the state of knowledge of several aversive agents (MRID 46760001) reports
acute toxici ty of denatonium saccharide to rats (LD 50 = 1430 mg/kg), shrimp (species not specified, LC 50 = 600 mg /L ), and rainbow trout ( LC 50 = 1500 mg /L ). Similar values were reported for denatonium benzoate; acute toxicity to rats (LD 50 = 612 mg/kg), shrimp (species not specified, LC 50 = 400 mg /L ), and rainbow trout ( LC 50 = 1000 mg /L ). No additional information was provided including the test material and the source of the data. Although the acute oral rat toxicity value reported for d enatonium benzoate is similar to the value observed in the submitted study (LD 50 = 648 mg ai/kg

- bw; MRID 47135802; discussed below), collectively there is considerable uncertainty in what these values represent given that the test material is unknown.8 The test material may have been TGAI or a formulation of unknown percent active ingredient in some or all the studies. Therefore, a comparison cannot be made among the endpoints reported in MRID 46760001 (denatonium benzote vs. denatonium saccharide) and tho se endpoints cannot be compared to the submitted denatonium benzoate studies which are discussed below. These values are not considered in the risk assessment given the considerable uncertainty due to a lack
of information about the studies.

Denatonium B enzoate Data

Acute Toxicity to F reshwater F ish

In a 96 h r acute toxicity study (MRID 47135816) with rainbow trout the LC 50 was >1000 mg /L

. The NOAEC = 500 mg /L and the LOAEC = 1000 mg /L based on 10% mortality

. Increased pigmentation and loss of equilibrium were observed; however, it was not specified which treatment groups exhibited these sub

- lethal effects. Therefore, a NOAEC value based on sub

lethal effects could not be determined. Information about the tes t material ( purity and description) was not reported and test concentrations were based on nominal concentrations. For the risk assessment, it was assumed that the test was conducted using the formulation containing the lowest percent denatonium benzoate (0.0078%; source: all previously USEPA

- registered denatonium benzoate products ; see Table 4 for additional details ). Th e study was classified as qualitative use because of uncertainty about test concentrations and the submission was a
summary report which did not include critical information

.

Acute Toxicity to F reshwater I nvertebrates

A 48 hr acute toxicity study with Daphnia magna was conducted in conjunction with a 21day chronic toxicity study (MRID 47135818)

. The 48 h r EC 50 = 10.2 ( 95% confidence interval; 7.7

- 14.0) mg /L

. T he NOAEC = 5 mg /L and the LOAEC = 10 mg /L based on mortality. Sublethal effects were not reported.

Acute Toxicity to Marine/Estuarine Invertebrates

In a 96 h r acute toxicity study with Crangon sp. the LC 50 = 554 mg /L (95% confidence interval;

412

- 755) . T he NOAEC = 125 mg /L and the LOAEC = 250 mg /L based on mortality (MRID 47135817) . Sublethal effects were not reported. Information about the test material ( purity and description) was not reported and test concentrations were based on nominal concentrations. For the risk assessment, it was assumed that the test was conducted using the formulation containing the lowest percent denatonium benzoate (0.0078%; source: all previously USEPA

- registered
denatonium benzoate products ; see Table 4 for additional details ). The study was classified as qualitative use because of uncertainty about test concentrations and the submission was a toxicity
summary report which did not include basic information about the experimental design and study
conditions.9 Chronic Toxicity to Freshwater Invertebrates

Chronic toxicity to Daphnia magna was studied under static renewal conditions (MRID 47135818) . The 21 day EC 50 = 4.6 ( 95% confidence interval; 3.2

- 6.4) mg /L . The NOAEC = 2

mg /L and the LOAEC = 5 mg /L based on adult mortality. The NOAEC ≥ 5 mg /L (LOAEC > 5

mg /L ) for first brood release and mean number of offspring per parent. Terminal growth of the
first

- generati on daphnia was not evaluated, thus the NOAEC was likely underestimated.

Algal Toxicity

(Freshwater Diatom)

In a 70.5 h r toxicity study with Nitzschia palea

, t he NOAEC = 5 mg /L for yield, growth rate, and area under the growth curve (MRID 47135819)

. The IC 50 was between 5 and 10 mg /L for all endpoints. Th e study was classified as qualitative use in part because the initial cell density was low and there was a lack of logarithmic growth after 45.5 hr

. T oxicity values may have been lower if logarithm ic growth had continued through 96 hr (minimum recommended test duration).

(Freshwater Green Algae)

Portugal (2008) reports toxicity of ARBINOL B (formulation containing denatonium benzoate)

to Scenedesmus subspicatus . The 72 h NOEC ≥ 100 mg /L ARBINOL B ( LOEC > 100 mg/L ARBINOL B; no effects at the highest test concentration). ARBINOL B contains 0.11 g
denatonium benzoate /L of product (EFSA, 2012); therefore, th e NOEC ≥ 0.011 mg denatonium
benzoate /L

. EFED has not reviewed this study and tak es the reported toxicity at face value for purposes of this assessment.

Acute Oral Toxicity to Birds

The 14

- day acute oral LD 50 = 196 ( 95% confidence interval; 145

- 264) mg ai/kg

- bw for n orthern
b obwhite quail (MRID 47146905). The Probit slope = 5.52. The 14

- day NOAEL = 50 mg ai/kg

- bw and the LOAEL = 100 mg ai/kg

- bw based on treatment

- related mortality. Unsteady and/or subdued behavior was observed in birds that subsequently died and birds that survived until study t ermination at the ≥1 00 mg ai/kg

- bw treatment levels. Recovery of affected birds was observed by day 6. No clinical signs of toxicity were observed in birds from the control, 25, or 50 mg ai/kg

- bw treatment levels. There were no apparent treatment

- related effects on body

we ight or feed consumption at any dosage level. The beak and front of the head were observed
to be wet in 9 of the 15 birds that d ied (100, 200, and 400 mg ai/kg

- bw treatment levels) ; no further explanation was provided regarding this observation . No treat ment

- related abnormalities were detected in any other birds.

Acute Dietary Toxicity to Birds

The acute dietary toxicity of denatonium benzoate to n orthern b obwhite quail was assessed over 11 days (5 day exposure) (MRID 47146906)

. The LC 50 = 5080 (95% confidence interval; 2520

to + infinity) mg ai/kg diet and the NOAEC < 657 mg ai/kg diet based on mortality. Observed10 mortality is assumed to be treatment related although pecking may have been a contributing
factor. There were no clear clinical sig ns of toxicity, effects on body weight, or effects on feed consumption. In addition, no treatment

- related gross pathological changes were observed.

The acute dietary toxicity of denatonium benzoate to mallard duck was assessed over 8 days (5 day exposu re) (MRID 47146907). The LC 50 > 5150 mg ai/kg diet. No treatment

- related effects were observed on mortality, body weight, or feed consumption. No clinical signs of toxicity
were observed and no treatment

- related observations were made at necropsy.

Acu te Oral Toxicity to Rats

The acute oral LD 50 = 648 mg ai/kg

- bw (95% confidence interval; 506

- 832 mg ai/kg

- bw) for female rats and 841 mg ai/kg

- bw (95% confidence interval; 707

- 1000 mg ai/kg

- bw) for male rats (MRID 47135802). Complete mortality was observed at the highest treatment rate (of three) within 30 minutes of dosing. Sublethal effects (hunched posture, lethargy, decreased respiratory

rate, ataxia, noisy respiration, or labored respirati on) were observed at the lowest two doses (500 and 707 mg ai/kg

- bw) up to two days after dosing. All surviving animals appeared normal throughout the remainder of the study. Necropsy revealed abnormalities in the animals that died during the study (hemorrhagic lungs, dark liver, dark kidneys, pale gastric mucosa, and hemorrhage or slight hemorrhage of the gastric mucosa) but not in the animals that survived.

Acute Toxicity to Bees

EFED does not have data for bees; however, data were reported by the Euro pean Food Safety Authority ( Portugal, 2008 ; EFSA, 2012)

. T esting was conducted with the formulation
ARBINOL B which contains denatonium benzoate. The acute oral 48 hr LD 50 > 362.5 μg
ARBINOL B/bee and the acute contact 48 hr LD 50 > 400 μg ARBINOL B/bee. ARBINOL B contains 0.11 g denatonium benzoate /L of product (EFSA, 2012) . Therefore, the acute oral 48 hr

LD 50 > 0.039 μg denatonium benzoate /bee and the acute contact 48 hr LD 50 > 0.044 μg denatonium benzoate /bee

. Mortality was ob served in the acute oral test at three of the five test concentrations (25, 200, and 400 μg ARBINOL B/bee). EFED assumes that it is more likely that the mortality was background noise and not treatment related given that the mortality was 3.3% at each of those test concentrations and there was no dose response. No mortality was observed
in the acute contact test . EFED has not review ed this study and takes the reported toxicity at face value for purposes of this assessment.

Incident Information

No incidents involving denatonium saccharide were reported in the Ecological Incident Information System (EIIS, v 2.1.1 ), the Aggregate Inci dent Data System , or the Avian Incident Monitoring System (AIMS) 2 as of September 25

, 201 3

.

2 http://www.abcbirds.org/abcprograms/policy/ toxins /aims/aims/index.cfm11 V. Risk Characterization

Denatonium saccharide toxicity and fate data were recommended in the problem formulation; however, none are available at this time except for an acute oral toxicity to rat study. Analog chemicals have not been identified ( http://aim.epa.gov/ ); however, limited data are available for denatonium benzoate, which shares the same denatonium cation with de natonium saccharide. Denatonium benzoate toxicity was used as a surrogate for denatonium saccharide given that it is
the best available information. Risk to mammals could not be assessed using the submitted
denatonium saccharide data because of the lack of mortality at the limit test concentration which is lower than estimated environmental concentrations; therefore, submitted denatonium benzoate
data was used to better characterize risk to mammals. The denatonium cation was assumed to be primarily respo nsible for denatonium saccharide toxicity. This assumption is considered
reasonable because saccharine (sodium saccharide ) is a synthetic sugar found in many food products. Therefore, the risk characterization of denatonium saccharide was based on
denato nium cation toxicity and exposure. The risk characterization is qualitative (i.e., RQs were not calculated) given the inherent uncertainty in using the denatonium benzoate data. Furthermore, there is uncertainty in the exposure estimates given the lack o f fate data and general
lack of use restrictions on the labels. Based on the characterization, lack of denatonium saccharide acute toxicity data for birds and honeybees has the greatest potential impact on the
risk conclusions. Risk conclusions are not e xpected to change for other taxa.

Chronic risk to aquatic and terrestrial organisms is assumed to be negligible given the limited
and localized use of denatonium saccharide in addition to the limited annual use (less than 100 lb
denatonium saccharide is sold per year according to the registrant ; USEPA, 2011 ) 3

.

Aquatic Organisms

Based on the qualitative assessment, it is unlikely that there would be a risk concern for aquatic organisms from the use of denatonium saccharide

. Direct adverse effects to aquatic organisms are not expected.

For aquatic exposure, it was assumed that uses of denatonium saccharide may result in contamination of surface water, although exposure is expected to be low based on the nature of
the label ed uses. It was assumed that exposure would occur primarily from runoff water transporting denatonium saccharide directly into surface waters or indirectly through storm sewers. Runoff could come from all labeled uses, although primarily from application s to impervious surfaces and unburied seeds. Spray drift is assumed negligible based on the application methods (most likely hand

- held trigger sprayers 4 ). The labeled uses of denatonium saccharide will likely result in multiple, relatively small, spatial ly and temporally variable applications. Given the type of application and lack of fate data, standard aquatic exposure modeling (e.g. PRZM/EXAMS) was not used to directly calculate EECs for denatonium

3 An assessment of chronic risk to aquatic invertebrates is presented given that denatonium benzoate toxicity data
were available.

4 There are no restrictions on the application equipment except that the sprayer should be able to deliver a coarse droplet size and that mist blowers and ultra low volume sprayer are prohibited. It is assumed that hand

- held sprayers are the most likely sp ray equipment given the residential use.12 saccharide. Instead, for illustrative purposes, aqua tic exposure was estimated based on dilution of denatonium saccharide (i.e. denatonium equivalent) directly into the standard farm pond.

A concentration of 0.078 μg denatonium/L would result from spraying an entire bottle of RO

PEL ( 1 gallon 5 ; 0.065% dena tonium saccharide) directly into a 20 million liter pond (i.e., standard farm pond) assuming no degradation or sorption. Even with this conservative scenario, it would require the simultaneous discharge of many gallons of RO

- PEL into the standard farm

po nd before there would be a risk concern for aquatic organisms ( Table 4 ).

5 The RO

- PEL label is for a 1 gallon product. Each gallon contains 0.0054 lb denatonium saccharide (0.065% ai x 8.34 lb/gallon = 0.0054 lb ai). 1 gallon of RO

- PEL in the standard farm pond results in a concentrati on of 0.122 μg denatonium saccharide/L (2,449,399 μg denatonium saccharide per gallon/20,000,000 L) or 0.078 μg denatonium/L (0.122 μg denatonium saccharide/L x 0.641). Molecular weight ratio of denatonium (325.48) to denatonium saccharide (507.64) = 0.6 41.13 Table 4

. Amount of RO

- PEL Required to be a Risk Concern to Listed Aquatic Organisms 1

Taxa Peak EEC from one gallon of

RO

- PEL (μg
denatonium /L ) 2 Toxicity 1 Number of gallons of

RO

- PEL to
exceed LOC (high estimate) 3 Toxicity 2 4 Number of gallons of RO

PEL to exceed

LOC (low estimate) 3

Freshwater fish (acute) 0.078 L C 50 > 728,000 μg
denatonium /L >466667 L C 50 > 56 μg
denatonium /L > 36 5

Freshwater
invertebrate (acute) 6 0.078 EC 50 = 742 5

μg denatonium /L 47 60 NA NA

Marine/estuarine
invertebrate (acute) 0.078 L C 50 = 403 312

μg denatonium /L 258333 L C 50 = 31 μg
denatonium /L 20 5

Freshwater
invertebrate (chronic) 7 0.078 NOAEC = 1456 μg
denatonium /L 18667 NA NA

Marine/estuarine
invertebrate (chronic) 7,8 0.078 NOAEC =
79080 μg denatonium /L 1013846 NOAEC = 6.2 μg
denatonium /L 79 5

Algae (listed species) 6 0.078 NOAEC = 3640 μg
denatonium /L 46667 NA NA

1 Exposure and toxicity of denatonium saccharide expressed in terms of denatonium cation.

2 EEC based on one gallon of RO

- PEL added directly to the standard farm pond (20,000,000 L ) and assuming complete mixing.

3 Acute endpoints: Number of gallons RO

- PEL = (toxicity as μg denatonium /L x 0.05)/0.078 μg denatonium /L . Chronic endpoints and a lgae (listed species): Number of gallons RO

- PEL = (toxicity μg denatonium /L x 1) /0.078 μg
denatonium /L

. The acute listed species LOC = 0.05. The chronic LOC and the alg ae (listed species) LOC = 1.

4 In some studies, information about the test material including purity was not reported and test concentrations were based on nominal concentrations (“toxicity 1” assumes that the test material was TGAI and 100% purity). “Toxicity 2” assumes that the test was conducted using the formulation containing the lowest percent denatonium benzoate (0.0078%; source: all previously USEPA

- registered denatonium benzoate products). See footnote 5 for more information.

5 The test mater ial used in the studies was Bitrex®. According to the Bitrex website (www.bitrex.com) , 0.256% is the lowest percentage of denatonium benzoate in currently available Bitrex® product s

. If toxicity is based on that percentage
then the low end number of gall ons of RO

- PEL to exceed the LOC would be much greater than shown in Table 4 ; > 1194 for freshwater fish (acute), 66 2 for marine/estuarine invertebrates (acute), and 2590 for marine/estuarine invertebrates (chronic).

6 Portugal (2008) and EFSA (2012) report toxicity of ARBINOL B (formulation containing 0.11 g /L denatonium benzoate ; EFSA, 2012 ) to Scenedesmus subspicatus (72 h NOEC ≥ 100 mg /L ARBINOL B or ≥ 0.011 mg denatonium benzoate /L )
and Daphnia magna (48 h EC 50 > 500 mg /L ). It is not clear if the Daphnia toxicity value is reported in terms of active ingredie nt or formulation (ARBINOL B) ; thus, the Daphnia toxicity value could be EC 50 > 0.055 mg denatonium
benzoate /L . The Scenedesmus subspicatus and potentially the Daphnia toxicity value are lowe r than those in the
submitted Nitzschia palea (algae) and Daphnia studies; however, no mortality was observed in the acute toxicity of

ARBINOL B to Daphnia magna study and no effects were observed in the ARBINOL B toxicity study with Scenedesmus subspicatus. These endpoints are not considered further because they would not change the risk conclusions (even assuming that the toxicity values represented a definitive endpoint, the gallons of RO

- PEL to exceed the LOC is >102 for
Scenedesmus and >26 f or Daphnia ).

7 Peak EEC was used as a conservative estimate of chronic exposure (21 days for invertebrates).

8 Toxicity estimated wit h acute

- to

- chronic ratio using available data (ACR = acute toxicity to Daphnia (LC 50 = 10.2

mg /L )/chronic toxicity to Daphnia (NOAEC = 2 mg /L ). ACR = 5.1 is applied to the acute toxicity to Crangon sp

. (LC 50 = 554 mg /L ). Chronic marine/estuarine toxicity = 108.6 mg denatonium benzoate /L or 79080 μg denatonium /L

. NA = Not applicable14 Twenty gallons of RO

- PEL is the mini mum volume required to trigger a risk concern for listed species. 6 Actual exposure is expected to be much lower. The following conservative hypothetical scenario was considered :

1. The standard agricultural field simulated using PRZM has an area of 24.7 acres (10 ha).
Within that 10 ha it is assumed that there are 58 residential lots ( see EFED’s 2010

California red

- legged frog assessment for carbaryl 7 )

2. Every home in that neighborhood has a deck with an area of 200 ft 2 . The total area of

deck surface is 11600 ft 2 /10 ha.

3. Each homeowner purchases a gallon of RO

- PEL and all decks in the neighborhood are

treated at the rate of 1000 ft 2 (one gallon treats 1000 to 4000 ft 2 ). This would result in 11.6 gallons of RO

- PEL applied /10 ha

4. This volume is slightly mo re than half that needed to trigger a risk concern (20 gallons

a pplied directly to the waterbody). Concentrations would still not be high enough to trigger a risk concern even if the 11.6 gallons was applied to all the decks, was simultaneously washed off all the decks

, and all the denatonium entered the standard farm pond without loss of material.

Although there are uncertainties about application rates and the toxicity data (i.e., use of denatonium equivalent toxicity to represen t denatonium saccharide toxicity, lack of data on all required test species, and questions about the quality of some of the denatonium benzoate studies), that uncertainty is likely offset by the conservative assumptions about the fate of
denatonium sacchar ide (all applied material ends up in the water body) and the large volumes of

RO

- PEL needed to trigger a risk concern.

Terrestrial Organisms

Based on the qualitative assessment, it is unlikely that there would be a risk concern for terrestrial plants f rom the use of denatonium saccharide if data were available for quantitative assessment (i.e., if RQs were calculated); however, there is a risk concern for birds (listed and

non

- listed species) 8 and mammals (listed species)

. Risk could not be assessed fo r bees visiting flowers that develop from treated seeds, treated bulbs, and plants that take up denatonium saccharide used to treat structures (run

- off or spray drift exposure ) because the only known toxicity study with bees resulted in a non

- definitive endpoint at a test concentration that is lower than exposure estimates

.

RO

- PEL is specifically labeled as a bittering agent used as a deterrent to mammals (squirrels, voles, dog s, and cats) but not birds or terrestrial invertebrates . It was assumed that some

6 This is the most conservative estimate for marine/estuarine invertebrates. It was assumed that the product used for testing was the one containing the lowest percentage denatonium benzoate. Previously USEPA

- registered products contained 0.0078% (1 product), 0.065% (2), 0.025% (1), and 0.2% (15) denatonium benzoate. The test material, Bitrex®, may have had a greater percentage of denatonium benzoate than those products (see Table 4 footnotes).

7 http://www.epa.gov/oppfead1/endanger/litstatus/effects/redleg

- frog/2010/carbaryl

- deltasmelt/appendix

- g.pdf

8 Toxicity data are not available for a passerine species which are potentially mo re sensitive to denatonium saccharide than larger birds due to their smaller size and higher metabolic rate.15 mammals, birds, and terrestrial invertebrates may not be deterred from consuming denatonium saccharide in the absence of evidence to the contrary. It is a reasonable assump tion given that studies indicate that denatonium (typically as denatonium benzoate) does not deter all animals
and deterrence is often dependent on concentration. For instance, German wasps were not
deterred from denatonium benzoate treated bait at a conc entration of 10 ppm in one study ( Sackmann et al. 2010 ) and diamondback moth were not deterred from consuming denatonium benzoate treated leaves up to a concentration of 50 mg/ L in another study (Perera et al., 2000)

. Although counter

- intuitive given the labeled use of RO

- PEL, some mammals may not be
deterred by denatonium saccharide . For example, two studies showed that bank vols (Kleinka u f et al., 1999) and pocket gophers (Witmer et al., 199 8 ) were not deterred from consuming food
items treated with den atonium benzoate. Furthermore, denatonium benzoate is used in baits for
commensal rodents (e.g., Talon ® and RIDAK TM ) to prevent accidental ingestion of the bait by
children. Studies submitted to the USEPA indicate that at least some birds may not be deter red. A submitted efficacy study indicates that geese showed dislike for the taste of RO

- PEL treated
turf ( observed shaking their heads) but they continuously tasted the treated turf until moving into a patch of untreated turf and returned to the treated area at a later time (MRID 44589301 )

. T wo avian dietary studies with denatonium benzoate showed no evidence of food avoidance by

m allard duck or b obwhite quail (MRID 47146906 and 47146907 ). Nonetheless, some animals may be deterred, thus reducing risk. The degree to which this may be the case for any given species cannot be addressed with the available information.

Risk to terrestrial plants (all uses)

Any risk to terrestrial plants would be from runoff given the small scale use and type of application equipment. Risk from spray drift is negligible

. There are no terrestrial plant toxicity
data for denatonium saccharide or denatonium benzoate. T here are no incidents with denatonium saccharide involving plants, however, there is one minor plant incident involving denatonium benzoate (no details are available; source : Aggregate Incident Data System ). Although the label states that RO

- PEL should no t cause damage to plants (it is labeled for use on seeds, bulbs, and woody parts of plants) , it also states that treated seeds should be tested for germination. It is reasonable to expect that denatonium saccharide may be toxic to terrestrial plants at so me concentration given that algae growth (freshwater diatom) was inhibited from exposure to denatonium benzoate. Although toxicity was observed, exposure to nearly 50,000 gallons of RO

- PEL (i.e., applied directly to the standard farm pond) would be requir ed to cause a risk concern for algae (listed species). For perspective, less than 100 lb denatonium saccharide (ca. 18,500 gallons of RO

- PEL) is sold on an annual basis according to the registrant (USEPA, 2011) . There is no expectation that terrestrial p lants and algae are equally sensitive to
denatonium saccharide and aquatic exposure cannot be directly compared to potential terrestrial

exposure ; however, adverse effects on listed terrestrial plants from use of RO

- PEL seems unlikely given the large volum es of RO

- PEL required to affect algae and the limited use of the product.

Risk from use on seed

There is a risk concern for birds (listed and non

- listed) and mammals (listed) consuming treated
seeds

. Risk could not be assessed for bees visiting flowers that develop from treated seeds16 because the only known toxicity study with bees resulted in a non

- definitive endpoint at a test concentration that is lower than exposure estimates.

There is potential exposure to birds, mammals, and terrestrial invertebrates (pollinators) from use of denatonium saccharide on seeds. Two exposure pathways were considered. First, birds and mammals may consume treated seeds which are not required to be incorporated. Seco nd, it is
assumed that denatonium saccharide is transported into the above ground parts of the plant ; thus, pollinators could be exposed to residues in pollen and nectar (USEPA, 2012)

. Available
information indicating that denatonium saccharide is soluble and has a low Kow is consistent with this assumption.

The RO

- PEL label does not specify the type of seeds (i.e., plant species) that may be treated or the application rate (“spray until thoroughly soaked”). Grasses were used as representative seeds
becau se grass seed is the most commonly planted seed around residences and the aggregate surface area of grass seeds is expected to be greater than any other seed planted in residential

areas (USEPA, 2013) . Therefore, grass seed use should result in greater exposure than any other seed planted around residences. The types of seed (seven common species), number of seeds/lb, seeding rates, and estimated application rate s were provided by BEAD (USEPA, 2013). According to BEAD (communication with Jonathon Becke r) the recommended seeding rates are applicable to establishing a new lawn and overseeding applications would require lower seeding

rates

. EECs and RQs were calculated in T

- REX (v 1.5. 2 ). A representative output is presented

in Appendix A

.

At the highest application rate (1 gallon RO

- PEL/1000 ft 2 ), t he EEC s (avian Nagy dose) from the
seed treatment (all seven grass seeds evaluated) are more than 1/10 th (ca. 11 % 9 to 282%) of the

LD 50 for 20 g birds 10 . EECs for two type of grass seed, bluegrass and colonial bentgrass, are
more than 1/10 th (ca. 12% and 40%, respectively ) of the LD 50 for 1000 g birds . Even at the lowest application rate (1 gallon RO

- PEL/4000 ft 2 ), colonial bentgrass EECs are equal to or
more than 1/10 th of the LD 50 for the 20 g (72%) , 100 g (32%), and 1000 g (10%) birds size classes. This risk evaluation assumes that there is enough seed on the field to meet the daily dietary needs of a bird based on typical seeding rates and recognizes that the label does not require soil incorporat ion. A bird may not consume 100% of its daily diet as treated seeds; however, a s little as 4% of the diet of a listed bird would need to be RO

- PEL treated seed to be a risk concern ( Table 5 ). Table 5 presents a characterization of consumption of seed treated at the maximum application rate resulting in an exposure that is 1/10 th the LD 50 (i.e., RQ = 0.1). For example, a 20

- g bird would not exceed the listed species LOC if it consumed less than 4% ( 2419
or less seeds) of its daily diet as treat ed colonial bentgrass seed but that same bird would exceed
the listed species LOC if it consum ed 4% or greater ( 2420 or more seeds) of its daily diet as
treated colonial bentgrass seed

. A small foraging area would be required to consume enough
seeds to be a risk concern; in some cases the area is less than 1 ft 2 (e.g., the seeding rate for colonial bentgrass is 9195 seeds/ft 2 and a 20 g listed bird would only need to eat 2420 seeds to be of concern).

9 For example, an EEC that is 11% of the LD 50 represents an RQ = 0.11.

10 A risk concern is triggered for listed species for EECs ≥ 1/10 th the LD 50 (i.e., RQ = 0.1). There is also a risk
concern for non

- listed birds (EECs ≥ 1/2 the LD 50 ) consuming colonial bentgrass treated at both 1 gallon RO

PEL/1000 ft 2 and 4000 ft 2 rates (20g and 100g birds) and bluegrass treated at the 1000 ft 2 rate (20 g birds ).17 For this assessment it is assumed that a bird can cons ume seed up to 100% of its daily dietary needs and that the seed is readily available for foraging. It is unknown what rate a bird will consume seeds distributed on the ground; however, it is expected to vary with species and availability of the seed. Th e likelihood that a bird will consume enough seed to exceed the LOC will depend on factors including the individual bird, the availability of the seed, and how many treated seeds must be consumed to attain a dose of concern. Therefore, the likelihood of a n individual attaining that dose decreases with increasing number of seeds and increasing foraging area. For example, all things being equal, a larger bird will need to forage for a greater number of seeds over a greater area than a smaller bird, likely i ncreasing the amount of time spent foraging exclusively on treated seeds and perhaps the likelihood that enough seeds would be
consumed. The LOC exceedences are based on seeding rates for establishment of a new lawn. Overseeding a lawn (lower seeding rat es) is a more typical application of seed according to BEAD. In that case, foraging areas will be greater than presented. Any incorporation or covering of the seed (not required by the label) would further decrease availability, requiring greater effort and time to obtain enough seeds to attain a dose of concern. Of the three size classes, the likelihood of a risk concern is greatest for the smallest birds (20 g) given that the LOC is exceeded for all seven grass seed species, the relatively small numbe r of seeds needed to be consumed, and the small foraging area required to exceed the LOC (ca. 0.3

- 3 ft 2 ).

Risk to birds can also be characterized in terms of dietary toxicity data. At the highest application rate (1 gallon RO

- PEL/1000 ft 2 ), the EEC (1126.32 mg denatonium/kg seed) is more
than 1/10 th ( 30%) of the LC 50 for bobwhite quail (3698 mg denaton ium/kg

- bw) for one of the seven grass seeds (colonial bentgrass) 11 . This indicates a risk concern for listed birds at the highest application rate base d on one of the seven evaluated grass seeds. At all labeled application rates, t he EECs (≤ 323 mg denatonium/kg

- bw) are less than 1/10 th the LC 50 for the other six evaluated grass seeds (no risk concern for listed or non

- listed species).

11 See Appendix A for representative calculation of seed application rate.18 Table 5 . Characterization of Risk to Listed Birds from Consuming RO

- PEL Treated
Seeds 1

Seed Minimum # of treated seeds
consumed to exceed listed LOC (EEC ≥ 1/10 th LD 50 ) 2 % daily diet of listed birds consuming treated seeds to exceed listed LOC (EEC ≥ 1/10 th

LD 50 ) 3 Minimum foraging area (ft 2 ) to obtain enough seeds to exceed the listed LOC (EEC ≥ 1/10 th

LD 50 ) 4
20 g
bird 100 g
bird 1000 g
bird 20 g
bird 100 g
bird 1000 g
bird 20 g
bird 100 g
bird 1000 g
bird

red
fescue 2420 NA 5 NA 59 NA NA 2.2 NA NA

bluegrass 2420 15405 217599 12 28 8 7 1.4 8.8 123.8

tall
fescue 2420 NA NA 9 3 NA NA 1.7 NA NA

perennial

ryegrass 2420 NA NA 8 0 NA NA 3. 0 NA NA

chewings
fescue 2420 NA NA 48 NA NA 1.8 NA NA

hard
fescue 2420 15405 NA 37 8 2 NA 1.4 8. 7 NA

colonial bentgrass 2420 15405 217599 4 8 25 0.3 1.7 23.7

1 Based on the maximum labeled application rate, maximum number of seeds/lb from BEAD report (USEPA 2013), and the dietary needs for birds (20 g bird

– 5.06 g/day; 100 g bird

– 14.4 g/day; 1000 g bird

– 64.6 g/day) from T

REX (v 1.5. 2 ).

2 Minimum # treated seeds = (EEC (mg denatonium/kg

- bw/day) x bird weight (kg)) / 0.0000833 mg denatonium per
seed. EEC = 1/10 th of the size adjusted LD 50 . Size adjusted LD 50 reported in Appendix A.

3 % daily diet to exceed LOC = minimum # seeds to exceed LOC /# seeds equali ng 100% daily diet. # seeds equaling 100% daily diet = # seeds per g x daily dietary need for birds (g)

4 Number of seeds consumed/number of seeds per ft 2 = minimum foraging area (ft 2 ). For example (colonial bentgrass, 1000 g bird) : 217599 seeds consumed/9195 seeds per ft 2 = 23.7 ft 2 foraging area. Number of seeds/ft 2 is based on seeding rates provided in BEAD report. It is assumed that the lowest seeding rate is used for seed batches with the maximum number of seeds/lb when a range is provided for both rate and seeds/lb (tall fescue, perennial ryegrass, and Kentucky bluegrass) as advised in the BEAD report.

5 NA

– not applicable, EEC is less than 1/10 th of the LD 50
.

For mammals, t here is a risk concern for listed species at the highest application rate (1 gallon

RO

- PEL/1000 ft 2 ) but not at the lowest application rate (1 gallon RO

- PEL/4000 ft 2 )

. At the highest application rate, t he EEC s (mammal Nagy dose) are more than 1/10 th (ca. 12 % to 26%)
of the LD 50 for all size classes (15 g, 35 g, and 100g based on denatonium benzoate toxicity
data ) of mammals for use of denatonium saccharide on colonial bentgrass (one of the seven evaluated grass species) 12

. E ven at the highest application there is not a risk concern based on the six other grass species evaluated (EECs are less than 1/10 th of the size

- class adjusted LD 50 s). This risk evaluation assumes that there is enough seed on the field to meet the daily dietary needs
of a mammal based on typical seeding rates a nd recognizes that the label does not require soil incorporation. A mammal may not consume 100% of its daily diet as treated seeds; however, as
little as 38% of a listed mammals diet would need to be RO

- PEL treated seed to exceed the listed species LOC (E EC is greater than 1/10 th of the LD 50 ) ( Table 6 ). A relatively small foraging area (less than 2 ft 2 ) would be required for a 15 g mammal to consume enough seeds to exceed the

12 A risk concern is triggered for listed species for EECs greater than 1/10 th the LD 50
.19 listed species LOC (e.g., the seeding rate for colonial bentgrass is 9195 seeds/ ft 2 and a 15 g listed
mammal would need to eat 164 50 seeds to be of concern).

Table 6 . Characterization of Risk to Listed Mammals from Consuming RO

- PEL Treated
Seeds 1

Seed Minimum # of treated seeds
consumed to exceed listed LOC (EEC ≥ 1/10 th LD 50 ) 2 % daily diet of listed mammals consuming treated seeds to exceed listed LOC (EEC ≥ 1/10 th

LD 50 ) 3 Minimum foraging area (ft 2 ) to obtain enough seeds to exceed the listed LOC (EEC ≥ 1/10 th

LD 50 ) 4
15 g
mammal 35 g
mammal 1000 g
mammal 15 g
mammal 35 g
mammal 1000 g
mammal 15 g
mammal 35 g
mammal 1000 g
mammal

colonial bentgrass 5 164 50 31 056 38 3794 38 45 8 4 1.8 3.4 41. 7

1 Based on the maximum labeled application rate, maximum number of seeds/lb from BEAD report (USEPA 2013), and the dietary needs for mammals (15 g mammal

– 3.17 g/day; 35 g mammal

– 5.12 g/day; 1000 g mammal

– 33.95 g/day) from T

- REX (v 1.5. 2 ).

2 Minimum # treated seeds = (EEC (mg denatonium/kg

- bw/day) x mammal weight (kg)) / 0.0000833 mg denatonium per seed. EEC = 1/10 th of the size adjusted LD 50 . Size adjusted LD 50 reported in Appendix A.

3 % daily diet to exceed LOC = minimum # seeds to exceed LOC/# seeds equaling 100% daily diet. # seeds equaling 100% daily diet = # seeds per g x daily dietary need for mammals (g)

4 Number of seeds consumed/number of seeds per ft 2 = minimum foraging area (ft 2 ). For example (colonial bentgrass, 1000 g mammal) : 38 3794 seeds consumed/9195 seeds per ft 2 = 41. 7 ft 2 foraging area. Number of
seeds/ft 2 is based on seeding rates provided in BEAD report.

5 Colonial bentgrass is the only seed considered in this assessment with EECs greater than 1/10 th of the LD 50
.

For this assessment it is assumed that a mammal can consume seed up to 100% of its daily dietary needs and that the seed is readily available for foraging. It is unknown what rate a mammal will consume seeds distributed on the ground; however, it is expected to vary with species and availability of the seed. The likelihood that a mammal will consume enough seed to exceed the LOC will depend on factors including the individual mammal, the availability of the seed, and how many treated seeds must be consumed to attain a dose of concern. Therefore, the likelihood of an individual attaining that dose decreases with increasing number of seeds and increasing foraging area. For exa mple, all things being equal, a larger mammal will need to forage for a greater number of seeds over a greater area than a smaller mammal, increasing the amount of time spent foraging exclusively on treated seeds and perhaps the likelihood that enough seed s would be consumed. The LOC exceedences are based on seeding rates for establishment of a new lawn. Overseeding a lawn (lower seeding rates) is a more typical application of seed according to BEAD. In that case, foraging areas will be greater. Any
inc orporation or covering of the seed (not required by the label) would further decrease availability, requiring greater effort and time to obtain enough seeds to attain a dose of concern. The likelihood of a risk concern is about the same for small (15 g) a nd medium (35 g) sized mammals given the relatively small number of seeds needed to be consumed and the relatively small foraging area required to exceed the LOC (ca. 1.8

- 3.4 ft 2 ) in comparison to 1000 g
mammals.

Although the listed species LOC is exceeded, the potential risk to mammals is anticipated to be
low all things considered

. The risk concern is based on only one of the seven evaluated grass species and a lthough a small mammal may only need to consume 38% of its diet in treated seeds, it would only be in a situation where colonial bentgrass (or similar seed) i s planted. Possible20 options for reducing risk to listed mammals from use on colonial bentgrass (or similar seed) would be label changes such as requi ring seed incorporation or lowering the maximum application rate for seed use in areas where listed mammals that eat seeds may be present.

BEAD assumed a hypothetical seed size (3 mm x 1 mm) for estimating application rates to all seven grass species. Grass seeds such as fescue tend to be a bit larger and thus there would be more denatonium saccharide per seed. Therefore, risk would be greater than presented for some
seeds as a bird or mammal would need to eat a fewer number of seeds to consume the sam e amount of denatonium saccharide. Grass seeds are often sold as blends so the examples presented represent a range of potential outcomes in terms of risk.

Given the Tier 1 approach that assumes that denatonium saccharide is transported i nto above ground plant material, bees and other pollinators could be exposed to denatonium saccharide in the pollen and nectar of plants. A lthough grass seed is assumed the most typical use in a residential setting, other uses such a s wildflower seeds are possible

. A Tier 1 estimate of 1 μ g ai/g in pollen and nectar was proposed in the White Paper in Support of the Proposed Risk Assessment Process for Bees (USEPA

, 2012)

. The dietary exposure estimate for adult worker bees is 0.29 μg denatonium/bee based on food consumption rates and the assumed concentration in pollen and nectar. 13 Given the available information, risk could not be assessed for bees visiting flowers tha t develop from denatonium saccharide treated seeds because the only known toxicity study with bees resulted in a non

- definitive endpoint at a test concentration ( LD 50 > 0.029 μg denatonium/bee ) that is lower than the exposure estimate (0.29 μg denatonium/b ee). The screening concentration in pollen and nectar does not account for differences in application rate. Available data for seeding rates ranging from 0.7

‐ 1.25 mg ai/seed were used to evaluate the screening value which is expected to apply to pestici de treatments that are at a similar rate (the highest measured residues were 28x lower than the screening estimate). Denatonium saccharide rates are expected to be lower (0.0000833 mg denatonium/seed at the 1000 ft 2 rate 14 )
than those rates. Based on rate alone it may seem that nectar and pollen concentrations of denatonium may be lower than residues observed for other pesticides; however, the plants used to assess the screening value were relatively large (e.g., corn and soybean) compared to plants
most l ikely treated with denatonium at a residence (e.g., grass and wildflowers). Therefore, all things being equal, nectar and pollen concentration would be expected to be greater in smaller plants treated at the same application rate. Given the uncertainty, it is assumed that the 1 μ g ai/g screening value is applicable to the denatonium saccharide seed treatment despite the lower application rates. In conclusion, risk to bees could be assessed with denatonium saccharide toxicity data (adult and larval oral) that tests at a higher concentration or with a refined exposure estimate based on denatonium saccharide residue data for labeled use rates (EFED is not aware of any information at this time). Furthermore, risk would be negligible if information is
availab le that indicates that denatonium saccharide is not transported into plant material, although this seems unlikely given that it is water soluble and has a low K
ow .

13 EEC (0.29 μ g ai/bee) = 1 μ g denatonium/g x 0.29 g/day (USEPA, 2012)

14 Equations from BEAD report (USEPA, 2013): (0.2 mm 3 /1 seed) x (1 gallon/3785441.78 mm 3 ) x (8.345 lb/1 gallon) x (0.065%) x (453592.4 mg/1 lb) = 0.000129 mg denatonium saccharide/seed or 0.0000833 mg
denatonium/seed.21 Risk from run

- off from outdoor structures and surfaces

Given the Tier 1 approach that assumes denatonium saccharide is transported into above ground plant material, bees and other pollinators could be exposed to RO

- PEL applied to outdoor

structu res and surfaces that then runs off into vegetative areas and is taken up by plants. Two
Tier 1 estimates of pesticides in pollen and nectar were proposed in the White Paper in Support of the Proposed Risk Assessment Process for Bees ( USEPA 2012) : a 1 μ g ai/g default value that is a reasonably conservative estimate for pollen and nectar of crops treated with pesticides via soil applications and estimates using the Briggs model which accounts for application rate and physiochemical properties of the chemic al. Use of the Briggs model is preferred over the default value given that it accounts for application rate and pesticide specific characteristics; however, use of this model is inappropriate in this case because it is based on data from non

- ionic organic chemicals and denatonium saccharide is an ionic compound. Therefore, 1 μ g ai/g plant material was assumed a conservative estimate of denatonium saccharide in pollen and nectar. The dietary exposure estimate for adult worker bees is 0.29 μg denatonium/be e based on food consumption rates and the assumed concentration in pollen and nectar. 1 3 Given the available information, risk could not be assessed for bees visiting flowers that develop from plants that take up denatonium saccharide because the only known toxicity study with bees resulted in a non

- definitive endpoint at a test concentration ( LD 50 > 0.029 μg denatonium/bee ) that is lower than the exposure estimate (0.29 μg denatonium/bee). T he 1 μ g ai/g screening estimate is based on the maximum
value from data including pesticide residues measured in different plant parts (leaves, fruit, green part, inflorescence, whole plant, and grain) following applications to soil or seed treatments; the
value is considered conservative for soil treatments because avai lable data from residue studies following soil application showed pollen and nectar concentrations lower than 1 μ g ai/g with a single exception . Measured pollen and nectar concentrations were typically two orders of magnitude lower than 1 μg ai/g which would put the exposure estimate slightly less than 1/2.5 th
(i.e., LOC = 0.4) the honeybee LD 50 (> 0.029 μg denatonium/bee). The cited residue in pollen
and nectar data from other chemicals suggests a possibility that exposure to denatonium may not be hig h enough to be a risk concern; however, those estimates only represent a subset of chemicals and application rates. In conclusion, risk to bees could be assessed with denatonium saccharide toxicity data (adult and larval oral) that tests at a higher conce ntration or with a refined exposure estimate based on denatonium saccharide residue data for labeled use rates. Furthermore, risk would be negligible if information is available that indicates that denatonium saccharide is not transported into plant mater ial, although this seems unlikely given that it is
water soluble and has a low K
ow .

Risk from treated bulbs

There is no t a risk concern for mammals but there is a risk concern for listed and non

- listed birds consuming treated bulbs

. Risk could not be as sessed for bees visiting flowers that develop from treated bulbs because the only known toxicity study with bees resulted in a non

- definitive endpoint at a test concentration that is lower than exposure estimates.

Although it is assumed that treated bulbs will be buried, birds may grub below ground for plant
material (Gauthier et al., 2006 and DeGraaf et. al, 1985 ) and mammals (e.g. squirrels) are known to dig up and consume bulbs. Birds and m ammals that are not re pelled by concentrations of22 denatonium saccharide on the treated bulbs may consume all or part of the treated bulbs.

E xposed bulbs may be available to non

- grubbing birds given that denatonium saccharide works as a bittering agent targeting mammals such as squirrels (i.e.

, mammals may dig up the bulbs but be deterred from completely consuming them). Birds including galliformes and cranes consume bulbs (Harris, 2009); however, EFED does not currently have information about bulb consumption by listed species

.

EFED does not have information on bulb size but a web search of bulbs typically planted in residential settings (e.g., crocus, daffodils, tulips, hyacinth, etc.) suggests that 20

- 100 g/bulb is a reasonable approximation. At the test concentration pro posed by BEAD (1.74 mg denatonium/bulb was proposed as a conservative estimate), bulbs less than 19 7 g would be a risk concern for small listed birds (i.e., the EEC of a 197 g bulb would be 1/10 th the LD 50 of a 20 g bird) 15 and bulbs less than 28 g would be a risk concern for large birds (1000 g). Smaller bulbs would pose a greater risk because the concentration of denatonium in smaller bulbs would be
greater than larger bulbs given the “per bulb” application rate provided by BEAD. For example,
the EEC for a 20 g bulb would be 98 % of the LD 50 of a 20 g bird (i.e., RQ = 0. 98 ) and 14 % of
the LD 50 of a 1000 g bird. Therefore, the listed species LOC is exceeded for all size classes of birds (20 g to 1000 g) consuming treated b ulbs within the size range of 20

- 100 g/bulb (approximate range assumed for residential setting)

. For non

- listed birds, bulbs less than 40 g would be a risk concern for small birds (i.e., the EEC of a 40 g bulb would be 1/2 the LD 50 of a 20 g bird ) and bu lbs less than 6 g would be a risk concern for large birds (1000 g). This analysis
assumes that a bird consumes up to 100% of its daily diet as treated bulbs (20 g bird = 22.8 g/day and 1000 g bird = 29 1 g/day ; T

- REX v1.5.2 ); for example, to have a risk concern, a 20 g listed
bird would need to consume either 22.8 g (100% daily diet) of a treated 197 g bulb or 2 g ( 9 % daily diet) of a treated 20 g bulb 16

. There is a high degree of uncertainty in the potential exposure because in reality the actual concentration will be a function of the bulb size, porosity, amount of product applied, duration of spraying , amount of time the bulb is resident in soil, etc. The BEAD estimate is a conservative peak estimate because it is based on soaking a 50 g bulb in
a solution of RO

- PEL for 10 minutes. BEAD indicated that t his method would likely result in higher concentrations on the bulb than could be achieved from spraying bulbs as directed on the
label. Nonetheless, it appears possible that bulb concent rations could be high enough to be a
concern for listed and non

- listed birds assuming that the bulbs are available for foraging. The foraging area required to result in a risk concern would likely be small given that bulbs are typically clustered together in beds ; however, the density of flower beds with treated bulbs may be relatively low in a given residential area. Exposure from consuming above ground plant material is also possible assuming that denatonium is transported into the above ground plant

mat erial; however, concentrations in the above ground plant material are assumed to be lower

15 For example, the dose

- based EEC (20 g bird) = 1.74 mg denatonium/196.7 g bulb = 8.845 mg denatonium/kg bulb x 1.14 kg diet/kg

- bw = 10.08 mg denatonium/kg

- bw. Dose

- based toxicity for a 20 g bird (LD 50 ) = 100.8 mg denatonium/kg

- bw. Calculations for larger size classes are similar. An EEC that is 1/10th of t he LD 50 represents an RQ = 0.10. See T

- REX (v.1.5.2) for equations and dietary needs of different size classes. Size class adjusted toxicity (LD 50 ) is based on bobwhite quail and rat data ( Appendix A ).

16 The amount of bulb consumed to be a concern assumes that denatonium is evenly distributed throughout the bulb. For example, the dose

- based EEC (20 g bird) = 1.74 mg denatonium/20 g bulb = 87 mg denatonium/kg bulb x 1.14 kg diet/kg

- bw = 99.18 mg denatoniu m/kg

- bw. Dose

- based EEC to exceed listed species LOC (0.1) for a 20 g bird = 10.08 mg denatonium/kg

- bw. Mass of a treated 20 g bulb that would exceed the LOC = (10.08 mg denatonium/kg

bw)/( 99.18 mg denatonium/kg

- bw) = 0.101 x 20 g bulb = 2 g of a treate d 20 g bulb.23 than that on the bulb due to plant growth. There is a high degree of uncertainty in the potential exposure and risk to birds; however, it is within reason that there could be a risk concern at least in some situations; therefore, risk to birds cannot be precluded. There is no t a risk concern for

m ammals assuming that an application of 1.74 mg denatonium/bulb is conservative and that treated bulbs are at least 18 g (below EFEDs low end estimate on bulb weight).

Given the Tier 1 approach that assumes that denatonium saccharide is transported into above ground plant material ; bees could be exposed to denatonium saccharide in the pollen and nectar of plants (USEPA, 2012)

. EFED does not currently have methodology for assessing systemic risk from bulbs. As a screen, it was assumed that the applicatio n rate on the bulb is translocated throughout the plant without loss of material. EFED does not have information about the mass
of the non

- bulb parts (i.e., stems, leaves, pollen, nectar, fruit and/or seeds) for species that would typically be planted in a residential setting. As a first approximation, it was assumed that the

non

- bulb parts have at least the same mass as the bulb. That results in a total plant mass in the range of 40

- 200 g/plant for bulbs that are initially 20

- 100 g. R isk could not be a ssessed for bees visiting flowers that develop from treated bulbs because the only known toxicity study with bees
resulted in a non

- definitive endpoint at a test concentration that is lower than exposure estimates for plants of a mass reasonably expected t o develop from bulbs planted in a residential setting

. Assuming an application rate of 1.74 mg denatonium/bulb, the exposure estimate is greater than
1/2.5 th (i.e., LOC = 0.4) of the bee oral LD 50 (> 0.029 μg denatonium /bee ) for plants weighing
less than 96 lb 17

. In conclusion, risk to bees could be assessed with denatonium saccharide toxicity data (adult and larval oral) that tests at a higher test concentration or with a refined exposure estimate based on denatonium saccharide residue data for labeled u se rates. Furthermore, risk would be negligible if information is available that indicates that denatonium saccharide is not transported into plant material, although this seems unlikely given that it is
water soluble and has a low K
ow .

VI. Risk to List ed Species

Based on this screening

- level assessment, there are potential risks of direct effects to listed mammals and birds from the use of denatonium saccharide on some of its registered use sites (uncertainties are discussed in Section V) . Listed mamm al

, bird , terrestrial plant, and aquatic vascular plant taxa may also be affected through indirect effects because of the potential direct
effects on listed and non

- listed species (expected only if a species has an obligate/dependent relationship with a bi rd or mammal given the limited use pattern)

. Potential direct effects on
listed mammals and birds from the use of denatonium saccharide may be associated with modification of Primary Constituent Elements (PCEs) of designated critical habitats, where such designations have been made. However, a t this current stage of the Registration Review process, it is premature to make effects determi nations for listed species until further scientific analysis and refinements are conducted, based on recommendations received from the National Academy of Sciences’ (NAS) National Research Council (NRC) April 2013 report, available at http://www.nap.edu/catalog.php?record_id=18344 . The NAS report outlines recommendations

17 1744 μg denatonium/43600 g plant = 0.04 μg denatonium/g plant. EEC ( 0.0116 μg denatonium /bee) = 0.04 μg denatonium/g plant x 0.29 g/day. The exposure estimate is based on the assumed concentration in pollen and nectar ( 0.04 μg denatonium /g plant) and the food consumption rate of adult worker bees (0.29 g/day) (USEPA, 2012). The
acute oral LD 50 > 0.029 μg denatonium /bee. 43600 g = 96.1 lb24 on specific scientific and technical issues related to the development of pesticide risk assessments that are compliant with th e Endangered Species Act (ESA) and the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).

The EPA along with the U.S. Fish & Wildlife Service (USFWS), the National Marine Fisheries Service (NMFS) (collectively, the Services), and the U.S. Depart ment of Agriculture (USDA), released a summary of their implementation plan for assessing risks of pesticides to listed species ahead of the stakeholder workshop held on November 15, 2013. This plan was developed in response to the NAS’ recommendations, i ncluding a common approach to risk assessment as a way of addressing scientific differences between EPA and the Services. During the workshop, the agencies received feedback from the public on the interim scientific approaches that were developed as part of the initial implementation of the NAS recommendations. These approaches will be jointly implemented and vetted as part of a phased iterative process. Once fully vetted, EPA will further refine the listed species effects determination portion of this r isk assessment.

To make effects determinations for individual listed species, useful refinements may include, but are not limited to, analyses of: 1) more detailed, species

- specific ecological and biological data; 2) more detailed and accurate informati on on residential use patterns; and 3) sub

- county level spatial proximity data for the co

- occurrence of potential effects areas and listed species and any designated critical habitat. Examples of such refinements are described below.

EFED is currently de veloping tools that are expected to further refine the assessment and are designed to support effects determinations for individual federally listed species and their designated critical habitats (where applicable). Scientific information obtained from th e Services, and other reliable sources is being collated by EFED to address all currently listed species. This information is being stored in an Office of Pesticide Programs (OPP) P esticide

R egistration I nformation S yste M (PRISM) listed species knowledgeb ase. The listed species knowledgebase consists of an information repository that houses biological and behavioral information relevant to individual species ( e.g. , habitat, diet, and life history, including specific temporal and spatial associations) and a document repository that contains supporting documents ( e.g ., USFWS recovery plans) and electronic information ( e.g ., GIS data files). For terrestrial taxa, biological information relevant to the assessment ( e.g ., diet and body weight) will be used
to p arameterize exposure estimates using a method consistent with currently used methods in the

T

- REX and T

- HERPS models.

Refinements will also include more detailed analyses of the registered uses and specific use patterns that result in either “Likely to Adversely Affect” (LAA) or “Not Likely to Adversely Affect” (NLAA) determinations for federally listed species. The analyses may include more information on where, when, and how denatonium saccharide is used on all use sites

. Actual usage data (when avai lable) and national land

- cover datasets that indicate potential use sites [ e.g ., National Land Cover Dataset (NLCD), Cropland Data Layer (CDL)] may be used to support a more refined analysis of where denatonium saccharide is reasonably expected to be
used. Similarly, refinements on the timing of applications and a more in

- depth exploration of

use practices for denatonium saccharide may be included as part of the refinement.25 The refinements based on individual species data; additional, detailed usage info rmation, when available; and recommendations from the NRC report are expected to help to more accurately identify potential areas of effect and to better inform effects and habitat determinations for listed species and any designated critical habitats.

VII. Endocrine Disruptor Screening Program

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, reproductive, and general or systemic toxicity. These studies include endpoints which may be susceptible to endocrine influence, including effects on endocrine target organ histopathology,

orga n weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and chronic studies that assess growth, developmental and reproductive effects in different taxonomic groups. As part of registration review of denatonium saccharide

, EPA reviewed these data (denatonium benzoate data was used as surrogate data) and selected the most sensitive endpoints for relevant risk assessment scenarios from the existing hazard database. However, as required by FFDCA section 408(p), denatonium saccharide is subject to the endocrine screening part of the Endocrine Disruptor Screening Program (EDSP).

EPA has developed the EDSP to determine whether certa in substances (including pesticide active and other ingredients) may have an effect in humans or wildlife similar to an effect produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator may designate.” The EDSP emplo ys a two

- tiered approach to making the statutorily required determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal
syst ems. Chemicals that go through Tier 1 screening and are found to have the potential to interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 testing is designed to identify any adverse endocrine

- related effects caused by the substance, and
establish a dose

- response relationship between the dose and the E, A, or T effect.

Under FFDCA section 408(p), the Agency must s creen all pesticide chemicals. Between October 2009 and February 2010, EPA issued test orders/data call

- ins for the first group of 67 chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. A second list
of chemicals identified for EDSP screening was published on June 14, 2013 18 and includes some pesticides scheduled for registration review and chemicals found in water

. Neither of these lists should be construed as a list of known or likely endocrine disruptors.

Denatonium sacc haride is on List 2. List 2 represents the next set of chemicals for which EPA
intends to issue test orders/data call

- ins in the near future. For further information on the status

18 See ht tp://www.regulations.gov/#!documentDetail;D=EPA

- HQ

- OPPT

- 2009

- 0477

- 0074 for the final second list of

chemicals.26 of the EDSP, the policies and procedures, the lists of chemicals, future l ists, the test guidelines and the Tier 1 screening battery, please visit our website. 19

VI I I

. References

DeGraff, R.M., Tilghman, N.G., and Anderson, S.H. 1985. Foraging Guilds of North American Birds. Environmental Management. 9(6):493

- 536.

EFSA, 2012. Conclusion on the Peer Review of the Pesticide Risk Assessment of the Active
Substance Denatonium Benzoate ( http://www.efsa.europa.eu/en/efsajournal/pub/2483.htm )

Gauthier, G., Giroux, J.

- F., and Rochefort, L. 2006. The Impact of Goose Grazing on Arctic and Temperate Wetlands. Acta Zoologica Sinica. 52(supplement):108

- 111.

Harris, T. (ed.) 2009. National Geographic Complete Birds of the World . Retrieved from http://books.goo gle.com

Kleinkauf, A., Macdonald, D.W., and Tattersall, F.H. 1999. A Bitter Attempt to Prevent Non

Target Poisoning of Small Mammals. Mammal Review. 29(3) : 201

- 204.

Perera, D.R., Armstrong, G., and Senanayake, N. 2000. Effect of Antifeedants on the
Diamo ndback Moth ( Plutella xylostella ) and its Parasitoid Cotesia plutellae . Pest Management
Science. 56 : 486

- 490.

Portugal, 2008. Draft Assessment Report (DAR)

- public version

- Initi al Risk Assessment Provided by t he Rapporteur Member State Portugal for the Existing Active Substance Denatonium Benzoate of the Fourth Stage of the Review Programme Referred to in Article 8(2)
of Council Directive 91/414/EEC

Sackmann, P., Corley, J.C., Masciocchi, M., and Novas, G. 2010. Effects of the Bittering Agent

Denat onium Benzoate on the Success of Toxic Baiting of Pestiferous German Wasps ( Vespula germanica ). International Jou rnal of Pest Management. 56(1): 69

- 74.

USEPA. 2008. Problem Formulation for Ecological Risk Assessment for De natonium Saccharide (Amended). D352197

USEPA

. 2011. Response to Data Waiver Request for the Denatonium Saccharide (PC 129045) Registration Review Probl em Formulation Data Call In. D 352551

USEPA. 2012. White Paper in Support of the Proposed Risk Assessment Process for Bees
, September 11

– 14, 2012

USEPA. 2013 [Revised] Application Rate Information for Uses of RO

- PEL, a Ready

- To

- Use Liquid Bittering Agent Containing Denatonium Saccharide (PC Code 129045), April 24, 2013

19 http://www.epa.gov/endo/27 Witmer, G.W., Pipas, M.J., and Bucher, J.C. 199 8 . Fiel d Tests of Denatonium Benzoate to Reduce Seedling Damage by Pocket Gophers ( Thomomys talpoides Rich.). Crop Protection.
17:35

- 39.28 Appendix A

Representative Input and Output from T

- REX (v 1.5. 2 ) for Seed Treatment (Kentucky Bluegrass , 1 Gallon RO

- PEL/1000 ft 2 )

seed lb seed/

1000ft2 1 Seeds/lb 1 Seeds/A 2 lb denatonium

saccharide /1000 ft2 1 lb denatonium/A 3 mg denatonium/

seed 4 mg denatonium/

kg seed 5

Bluegrass 1 1758000 76768559 0.000503 0.0141 0.0000833 323.0

1 Values and calculations as in USEPA 2013

2 Seeds/A = (lb seed/1000 ft 2 ) x (seeds/lb) x (1000 ft 2 /0.0229 A)

3 lb denatonium/A = (lb denatonium saccharide /1000 ft 2 ) x (325.48 g denatonium/507.64 g denatonium saccharide ) x (1000

ft 2 /0.0229 A)

4 mg denatonium/seed = ((lb denatonium/A) / ( seeds/A)) x (453592.4 mg/lb)

5 mg denatonium/kg seed = ((seeds/lb) x (lb/0.4535924 kg)) x mg denatonium/seed

Endpoints Reported Tested Body Adjusted

LD50 Size class for adjusted

LD50 Weight (g)

Avian LD50: 142.70 203 100.80 Small (20g)

128.32 Medium (100g)

181.26 Large (1000g)

Mammalian LD50: 471.70 211 913.51 Small (15g)

739.13 Medium (35g)

319.70 Large (1000g)

Animal Size Crop Maximum Application

Rate Maximum Seed Application Rate Avian Nagy Dose Mammalian Nagy

Dose Available AI

(lbs ai/A) (mg ai/kg seed) (mg ai/kg

bw/day) (mg ai/kg

bw/day) (mg ai ft

- 2)

Small Kentucky bluegrass 0. 0141 323.00 81.75 68.43

0. 15 Medium 46.62 47.30

Large 2 0.87 10.97

Crop Risk Quotients†

Avian (20 g) Mammalian (15 g)

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic
Kentucky bluegrass 0.81 0. 07 NA 0. 07 0. 01 NA

Avian (100 g) Mammalian (35 g)

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic

Kentucky bluegrass 0.36 0. 01 NA 0. 06 0. 01 NA

Avian (1000 g) Mammalian (1000 g)

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic
Kentucky bluegrass 0.12 0.00 NA 0. 03 0.00 NA

Acute RQ #1 = (mg ai /kg

- bw/day) / LD50

Acute RQ #2 = mg ai ft

- 2 /(LD50*bw)