2

Table of Contents 

I. Introduction ................................................................................................................................. 3

A. General Background .............................................................................................................. 4

II. Scientific Assessments ............................................................................................................... 4

A. Human Health Assessment .................................................................................................... 5

B. Environmental Assessment .................................................................................................... 5

C. Alternatives Assessment ...................................................................................................... 10

D. Endocrine Disruptor Screening Program ............................................................................. 10

III. Interim Registration Review Decision .................................................................................... 11

IV. Next Steps and Timeline ......................................................................................................... 13

 
3

I. Introduction 

This document is the Environmental Protection Agency’s (EPA or the Agency) Interim 

Registration Review Decision for denatonium saccharide and is being issued pursuant to 40 CFR 

sections 155.56 and 155.58. A registration review decision is the Agency’s determination 

whether a pesticide meets, or does not meet, the standard for registration in the Federal 

Insecticide, Fungicide, and Rodenticide Act (FIFRA). The Agency may issue, when it 

determines it to be appropriate, an interim registration review decision before completing a 

registration review. Among other things, the interim registration review decision may (1) require 

new risk mitigation measures; (2) impose interim risk mitigation measures; (3) identify data or 

information required to complete the review; and (4) include schedules for submitting the 

required data, conducting new risk assessments or revising preliminary assessments, and 

completing the registration review. 

 FIFRA, as amended by the Food Quality Protection Act (FQPA) of 1996, mandated the 

continuous review of existing pesticides. All pesticides distributed or sold in the United States 

generally must be registered by the EPA based on scientific data showing that they will not cause 

unreasonable risks to human health or to the environment when used as directed on product 

labeling. The registration review program is intended to make sure that, as the ability to assess 

and reduce risk evolves and as policies and practices change, all registered pesticides continue to 

meet the statutory standard of no unreasonable adverse effects. Changes in science, public 

policy, and pesticide use practices will occur over time. Through the registration review 

program, the Agency periodically reevaluates pesticides to make sure that as these changes 

occur, products in the marketplace can continue to be used safely. Information on this program is 

provided as www.epa.gov/oppsrrd1/registration_review/. 

In 2006, the Agency implemented the registration review program pursuant to FIFRA 

section 3(g) and will review each registered pesticide every 15 years to determine whether it 

continues to meet the FIFRA standard for registration. 

Pursuant to 40 CFR Section 155.50, EPA formally initiated registration review for 

denatonium saccharide (case 7625). The following highlights significant events that have 

occurred during the registration review of denatonium saccharide: 

 June 25, 2008 – Publication of the Denatonium Saccharide Summary Document for a 60-

day public comment period. The Summary Document included the preliminary work plan 

(PWP) and was accompanied by the scoping document and problem formulation. 

 November 14, 2008 - Final Work Plan (FWP) for denatonium saccharide was signed -- 

no public comments were received during the 60-day comment period for the 

Denatonium Saccharide Summary Document; thus, the FWP did not modify the Summary 

Document. 

 A Data Call-In (DCI) was issued in January 2010 for a number of human toxicity, 

ecological toxicity, and environmental fate studies. Although the requested studies were 

not submitted, EPA completed the risk assessment for denatonium saccharide using 

available data and data from a surrogate chemical, denatonium benzoate. EPA plans to 
4

close out this DCI. These risk assessments were made available along with the Proposed 

Interim Registration Review Decision for public comment. 

 June 6, 2014 – The Denatonium Saccharide Draft Risk Assessments and Proposed 

Interim Decision published for a 60-day comment period. One comment was received 

from the Center for Biological Diversity (CBD) during the comment period concurring 

with EPA’s “no effect” conclusions for a number of species in the denatonium saccharide 

ecological risk assessment. CBD also reminded EPA of its obligations to consult with 

the Services on all Not Likely to Adversely Affect determinations for denatonium 

saccharide. 

 September 2014 – The Agency is now publishing the Denatonium saccharide Interim 

Registration Review Decision. 

Additional information on denatonium saccharide, including this Interim Registration 

Review Decision and the following supporting documents can be found in EPA’s public docket, 

EPA-HQ-OPP-2008-0441, accessed at www.regulations.gov. 

A. General Background

Denatonium saccharide is a bittering agent in a squirrel, vole, dog, and cat repellant 

registered for use on outdoor surfaces and structures such as trees, fences, poles, decks, planters, 

siding, garbage cans, and furniture. For structures, it is applied as a spray or with a paintbrush 

to the point of runoff. Additionally, the product is sprayed onto seeds and bulbs before planting. 

Although not explicitly stated on the product label, the product appears to be used only in 

outdoor residential areas. This product is for non-food uses only. There is only one registered 

end use product, RO-PEL, and only 110 pounds or less of denatonium saccharide active 

ingredient (a.i.) are sold in the U.S. annually. Denatonium saccharide was first registered in 

August of 1985 and so it was not subject to reregistration. There are few chemical alternatives to 

denatonium saccharide for protection of outdoor surfaces, structures, trees, seeds and bulbs. 

II. Scientific Assessments

 A summary of the Agency’s human health risk assessment, environmental fate and 

ecological risk assessment, and alternative assessment, Denatonium Saccharide: Qualitative Risk 

Assessment for Registration Review (May 2, 2013), Registration Review – Ecological Risk 

Assessment for Denatonium Saccharide (March 14, 2014), and Denatonium Saccharide 

Alternative Assessment (March 28, 2014), is presented below. For the detailed risk and 

alternatives assessments, see the denatonium saccharide public docket (EPA-HQ-OPP-2008-

0441) accessed at www.regulations.gov. 
5

A. Human Health Assessment 

 Hazard Characterization 

The toxicological database is considered adequate for characterizing hazard and assessing 

risk from denatonium saccharide. No toxicological endpoints of concern have been identified for 

denatonium saccharide. 

Dietary Exposure Assessment 

There are no registered food uses. Based on the use pattern and the compound's extreme 

bitterness, dietary exposure from food and drinking water is unlikely to occur. Therefore, a 

dietary exposure assessment was not conducted. 

 Food Tolerances 

There are no US tolerances established for denatonium saccharide. 

 Residential and Occupational Exposure 

Denatonium saccharide is only sold as a ready-to-use liquid formulation which can be 

applied using a trigger pump (spray bottle), paintbrush, or sprayer. Dermal and inhalation 

exposures to occupational and residential handlers may occur during application of this product. 

Post-application exposure is expected to be negligible due to the limited area of use. EPA 

concludes that risk from exposure to denatonium saccharide will not be of concern because of 

the targeted method of application with a coarse spray or paintbrush and the low dermal and 

inhalation toxicity observed from the available studies. 

B. Environmental Assessment 

There were a number of uncertainties in the environmental risk assessment for 

denatonium saccharide. The only available denatonium saccharide toxicity data could not be 

used, there were no fate data available, and the label did not specify an application rate for use on 

seeds and bulbs. Estimated application rates for seeds and bulbs were determined and used by 

the Agency in its assessments based on available label information. Therefore, the risk 

assessment for denatonium saccharide assumes no degradation of denatonium saccharide, an 

estimation of the application rate1

, and uses denatonium benzoate toxicity data as a surrogate for 

denatonium saccharide toxicity because it is the best available information. Denatonium 

benzoate and denatonium saccharide are both bittering agents that share the denatonium cation. 

 Aquatic Organisms

It was assumed that aquatic exposure may occur primarily from run-off. Spray drift was 

assumed to be negligible given the small scale use and type of application equipment. A 

conservative screening-level scenario was considered given the lack of fate data. Aquatic 

exposure estimates were based on the assumption that all product applied ends up in the standard 

water body without sorption or degradation. Even with this very conservative scenario, there is 

no risk concern given the large volumes of denatonium saccharide that would be needed to be 

 

1

 See EPA memo: Revised Application Rate Information for Uses of RO-PEL, a Ready –To-Use Liquid Bittering 

Agent Containing Denatonium Saccharide. April 24, 2013 
6

used to trigger a risk concern. Chronic risk to aquatic organisms is assumed to be negligible 

given the limited and localized use of denatonium saccharide. 

Terrestrial Organisms

Plants 

There is potential exposure to plants from applications of denatonium saccharide due to 

runoff. Spray drift is expected to be negligible given the small scale use and type of application 

equipment. It is unlikely that there would be a risk concern for terrestrial plants from the use of 

denatonium saccharide based on the qualitative assessment of denatonium saccharide. 

 Bees and other terrestrial insects 

 There is potential exposure to denatonium saccharide for bees and other terrestrial 

insects that could visit flowers that develop from treated seeds or treated bulbs, and from visiting 

plants that take up denatonium saccharide used to treat structures from run-off exposure. Spray 

drift is expected to be negligible given the small scale use and type of application equipment. 

However, the potential for risk from these exposures could not be assessed because, while the 

available data did not indicate any toxicity to bees, this single study did not test up to exposures 

that might occur from the labeled uses. 

Birds 

Acute risk to birds, which are also surrogates for reptiles and terrestrial-phase 

amphibians, was evaluated based on consumption of treated seed and treated bulbs. Chronic risk 

to birds is assumed to be negligible given the limited and localized use of denatonium 

saccharide. 

Seed 

The risk assessment considered possible exposure from seven types of grass seed 

commonly planted on residential lawns. Grass seeds were used as representative seed because 

grass 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. EPA 

estimated the application rate for the treated seed. This screening-level assessment assumed that 

a bird would consume treated seed from a residential lawn up to 100% of its daily diet and that 

seed is available for foraging. 

Potential risk was evaluated by comparing the estimated environmental concentration 

(EEC) derived from estimated application rates on the seven types of seeds with the avian LD50

value adjusted for 20 gram, 100 gram, and 1,000 gram size birds. For example, Table 1 presents 

all the seed type and bird size class combinations that exceed the listed species level of concern 

(LOC =0.1) based on the maximum estimated labeled application rate and on a bird consuming 

100% of its daily diet as treated seed. Table 1 includes the number of seeds necessary to reach 

the listed species LOC of 0.1, the minimum percent of a bird’s daily diet that would need to 

come from treated seed in order to reach the LOC, and the minimum forage area to obtain 
7

enough seed to reach the LOC. At the maximum application rate, the listed species LOC is 

exceeded for 20 gram birds for seven out of the seven types of seeds evaluated, for 100 gram 

birds for three out of the seven types of seeds evaluated, and for 1,000 gram birds, two out of the 

seven seeds evaluated exceeds the listed species LOC. 

For non-listed birds, risks of concern were only identified for two weight classes of birds 

consuming a subset of the seven seed types treated at the maximum estimated application rate. 

For 20 gram birds, potential risks of concern were identified for two out of the seven types of 

grass seed. For 100 gram birds, potential risks of concern were identified for only one out of the 

seven types of grass seed. 

Table 1. Characterization of Risk to Listed Birds from Consuming RO-PEL Treated 

Seeds1 

Seed Minimum # of treated seeds 

consumed to exceed listed 

LOC (EEC ≥ 0.1 LD50)

2 

% daily diet of listed birds 

consuming treated seeds to 

exceed listed LOC (EEC ≥ 0.1 

LD50)

3 

Minimum foraging area (ft2) 

to obtain enough seeds to 

exceed the listed LOC (EEC 

≥ 0.1 LD50)

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 

2,420 NA5 NA 59 NA NA 2.2 NA NA 

bluegrass 2,420 15,405 217,599 12 28 87 1.4 8.8 123.8 

tall 

fescue 

2,420 NA NA 93 NA NA 1.7 NA NA

perennial 

ryegrass 

2,420 NA NA 80 NA NA 3.0 NA NA

chewings 

fescue 

2,420 NA NA 48 NA NA 1.8 NA NA

hard 

fescue 

2,420 15,405 NA 37 82 NA 1.4 8.7 NA 

colonial 

bentgrass 

2,420 15,405 217,599 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 TREX (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 = 1/10th of the size adjusted LD50. Size adjusted LD50 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 birds (g) 

4

 Number of seeds consumed/number of seeds per ft2 = minimum foraging area (ft2). For example (colonial 

bentgrass, 1000 g bird): 217599 seeds consumed/9195 seeds per ft2

 = 23.7 ft2 foraging area. Number of seeds/ft2 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 0.1 of the LD50, equivalent to the listed species LOC. 

This analysis assumes that a bird will remain feeding on the treated residential area long 

enough to consume enough seed to obtain a dose of concern. Although in some cases a small 

foraging area was estimated to be sufficient to obtain a dose of concern, denatonium saccharide 

is expected to be used on small residential lawn areas. 
8

Bulbs 

The risk assessment also evaluates the potential risk for birds consuming treated bulbs. 

Treated bulbs will be buried after denatonium saccharide is applied, and so these bulbs must be 

brought back to the surface in order for there to be a complete exposure pathway. The risk 

assessment identified two possible scenarios by which this could occur. First, birds that might eat 

bulbs could dig them up from a lawn or garden themselves. Alternatively, a mammal such as a 

squirrel might dig up bulbs, be repelled by the denatonium saccharide, and leave them on the 

surface where they could be consumed by birds. 

The risk assessment assumed that bulbs typically treated and planted in a residential 

setting range in size from approximately 20 to 100 grams. This screening-level assessment 

assumed that a bird would consume part or all of treated bulbs from a residential lawn up to 

100% of its daily diet and that bulbs are available for foraging. 

Potential risk was evaluated by comparing the estimated environmental concentration 

(EEC) derived from EPA estimated application rates on bulbs with the avian LD50 value adjusted 

for 20 gram, 100 gram, and 1,000 gram size birds. There is a potential risk concern for all size 

classes of listed bird species eating part or all of treated bulbs up to 100% of their daily diet. 

There is also a potential risk concern for 20 gram non-listed species consuming treated bulbs less 

than 40 grams. Smaller bulbs pose a greater potential risk because the estimated concentration of 

denatonium saccharide increases as the bulb size decreases. 

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, and amount of time the bulb is resident in soil, along with other 

considerations. The application rate estimate is a conservative peak estimate because it is based 

on soaking a 50 gram bulb in a solution of RO-PEL for 10 minutes. This method would likely 

result in higher concentrations on the bulb than could be achieved from spraying bulbs as 

directed on the label. Also, it assumes the bulb is made available for consumption by being 

excavated by the bird, another animal, or process and that the denatonium saccharide on the bulb 

surface does not dissipate from the bulb. 

Mammals 

Acute risk to mammals was evaluated for consumption of treated grass seed and treated 

bulbs using the same approach that was used for birds. As it does for birds consuming seed, the 

risk assessment for mammals calculates the number of treated seeds a mammal would need to 

consume to attain a dose equal to the listed LOC. Assuming the highest estimated application 

rate, and considering the daily diet of three size classes of mammals, it was determined that the 

dose of concern for listed species could only be attained for one of the seven types of seeds 

evaluated, colonial bentgrass. There were no risk concerns identified for non-listed mammals 

consuming seed. There were no risk concerns for listed or non-listed mammals eating bulbs. 

Chronic risk to mammals is assumed to be negligible given the limited and localized use 

of denatonium saccharide. 
9

Endangered Species Assessment 

The Agency is making a Federally-listed threatened and endangered species (hereafter 

referred to as “listed”) determination for the ecological risk assessment of denatonium 

saccharide, as detailed in the memorandum Endangered Species Determination for Registration 

Review of Denatonium Saccharide, dated April 29, 2014. The Action Area for this assessment is 

assumed to be residential and developed areas based on the use pattern. 

The Agency is making a no effect (NE) determination for all listed species except (1) 

birds that may be directly affected from the consumption of seeds, birds and reptiles that may be 

directly affected from the consumption of bulbs, mammals that may be directly affected from the 

consumption of seeds, and terrestrial insects (non-subterranean species) that may be directly 

affected and (2) species that are indirectly affected based on having an obligate/dependent 

relationship with a species that is directly affected by denatonium saccharide. 

For those listed species for which an NE determination was not made, EPA is making a 

may affect (MA) but not likely to adversely affect (NLAA) determination for both direct and 

indirect effects. 

EPA believes there is a potential for direct effects to the following numbers of listed 

species (by taxa): 

 41 birds and 7 reptiles that may consume bulbs (no listed terrestrial-phase amphibians 

were identified) 

 28 birds, which are a subset of the 41 birds identified that may consume bulbs, that may 

consume seeds (no listed reptiles 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, reptiles, 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 based on insufficient data; exposure 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 invertebrates, if any 

exposure were to occur, cannot be quantified. The MA finding, for the above species, is also 

based on the assumption that the geographic range for those listed species overlaps with the 

action area and that individuals may visit the treatment area. The Agency notes that there are in 

fact 76 terrestrial invertebrate species that overlap with the action area. However, a NE 

determination is concluded for the 17 listed terrestrial invertebrate species categorized as 

subterraneous. In general, these species are unlikely to be exposed to labeled applications of 

denatonium saccharide because they are adapted to living in caves or similar underground 

habitats. 

The MA finding for indirect effects is limited to listed birds, reptiles, terrestrial-phase 

amphibians, mammals, terrestrial insects, and plants (terrestrial and aquatic vascular) that have 

an obligate relationship with a species that is directly affected by denatonium saccharide. A NE 
10

determination is concluded for indirect effects to listed species not having an obligate 

relationship with a species directly affected by denatonium saccharide due to the highly localized 

and short-term nature of any effects. 

A NLAA determination has been made for both direct effects, listed species are indicated 

above, and indirect effects, where the species have an obligate relationship with a directly 

affected species, 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) and the nature of the use. There is no 

expectation that large contiguous areas of treatment will occur, rather use is expected to result in 

very small treatment areas (less than a typical residential yard) scattered across the landscape 

with few treatment areas occurring anywhere simultaneously. Given the combination of widely 

dispersed and limited use, it is highly unlikely that individuals of a listed species will encounter 

areas of treatment. Therefore, risk is expected to be discountable because potential exposure will 

be confined to small patches isolated in space and time. 

C. Alternatives Assessment 

There are three animal repellent alternatives to denatonium saccharide for protection of 

outdoor surfaces, structures, trees, seeds and bulbs: methyl nonyl ketone, capsaicin mixture, and 

thiram. However, because each of these alternatives can only be used on a subset of uses, users 

may only have one alternative for some uses. Some of the alternatives have constraints that may 

limit their usefulness. Methyl nonyl ketone has a shorter period of residual activity and needs to 

be reapplied daily. The capsaicin/garlic oil/putrescent whole egg solid products have a strong 

aromatic smell that may be offensive to some users. Little is known about the efficacy of the 

alternatives relative to denatonium saccharide. 

D. 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, organ 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 its most recent registration decision for denatonium 

saccharide, EPA reviewed these 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 certain 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 employs a two-tiered approach to making the 
11

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 systems. 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 screen 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, including denatonium saccharide, identified for EDSP screening was published on June 

14, 20132

 and includes some pesticides scheduled for Registration Review and chemicals found 

in water. For further information on the status of the EDSP, the policies and procedures, the lists 

of chemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit our 

website.3 

In this interim decision, EPA is making no human health or environmental safety findings 

associated with the EDSP screening of denatonium saccharide. Before completing this 

Registration Review, the Agency will make an EDSP FFDCA section 408(p) determination. 

III. Interim Registration Review Decision

In accordance with 40 CFR sections 155.56 and 155.58, the Agency is issuing an Interim 

Registration Review Decision. Except for the EDSP and the endangered species components of 

the denatonium saccharide registration review case, the Agency has made the following interim 

decision: (1) no additional data are required at this time; and (2) no changes to the affected 

registrations or their labeling are needed at this time. 

The Agency is making a no effect (NE) determination for all listed species except (1) birds that 

may be directly affected from the consumption of seeds, birds and reptiles that may be directly 

affected from the consumption of bulbs, mammals that may be directly affected from the 

consumption of seeds, and terrestrial insects (non-subterranean species) that may be directly 

affected and (2) species that are indirectly affected based on having an obligate/dependent 

relationship with a species that is directly affected by denatonium saccharide. 

For those listed species for which an NE determination was not made, EPA is making a 

may affect (MA) but not likely to adversely affect (NLAA) determination for both direct and 

indirect effects. 

EPA believes there is a potential for direct effects to the following numbers of listed 

species (by taxa): 

 41 birds and 7 reptiles that may consume bulbs (no listed terrestrial-phase amphibians 

 

2

 See http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2009-0477-0074 for the final second list of 

chemicals. 

3 http://www.epa.gov/endo/
12

were identified) 

 28 birds, which are a subset of the 41 birds identified that may consume bulbs, that may 

consume seeds (no listed reptiles 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, reptiles, 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 based on insufficient data; exposure 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 invertebrates, if any 

exposure were to occur, cannot be quantified. The MA finding, for the above species, is also 

based on the assumption that the geographic range for those listed species overlaps with the 

action area and that individuals may visit the treatment area. The Agency notes that there are in 

fact 76 terrestrial invertebrate species that overlap with the action area. However, a NE 

determination is concluded for the 17 listed terrestrial invertebrate species categorized as 

subterraneous. In general, these species are unlikely to be exposed to labeled applications of 

denatonium saccharide because they are adapted to living in caves or similar underground 

habitats. 

The MA finding for indirect effects is limited to listed birds, reptiles, terrestrial-phase 

amphibians, mammals, terrestrial insects, and plants (terrestrial and aquatic vascular) that have 

an obligate relationship with a species that is directly affected by denatonium saccharide. A NE 

determination is concluded for indirect effects to listed species not having an obligate 

relationship with a species directly affected by denatonium saccharide due to the highly localized 

and short-term nature of any effects. 

A NLAA determination has been made for both direct effects, listed species are indicated 

above, and indirect effects, where the species have an obligate relationship with a directly 

affected species, 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) and the nature of the use. There is no 

expectation that large contiguous areas of treatment will occur, rather use is expected to result in 

very small treatment areas (less than a typical residential yard) scattered across the landscape 

with few treatment areas occurring anywhere simultaneously. Given the combination of widely 

dispersed and limited use, it is highly unlikely that individuals of a listed species will encounter 

areas of treatment. Therefore, risk is expected to be discountable because potential exposure will 

be confined to small patches isolated in space and time. 

The number of species that could be indirectly affected because of an obligate 

relationship with a species that is directly affected by denatonium saccharide will be determined 

in coordination with the Services during consultation. 

Tables showing the listed species included in the NLAA determination for direct effects 

from the use of denatonium saccharide are found in the memorandum Endangered Species 

Determination for Registration Review of Denatonium Saccharide, dated April 29, 2014. EPA 

plans to request the U.S. Fish & Wildlife Service (USFWS) to provide concurrence on the 
13

NLAA endangered species determinations for denatonium saccharide prior to the issuance of the 

Registration Review Decision for denatonium saccharide. 

IV. Next Steps and Timeline 

A Federal Register Notice will announce the availability of this Interim Registration 

Review Decision for denatonium saccharide. A final decision on the denatonium saccharide 

registration review case will occur after an FFDCA section 408(p) EDSP determination has been 

made and after receiving concurrence from the USFWS on the NLAA endangered species 

determinations.