Human Health and Ecological Risk Assessment

for the Use of Wildlife Damage Management Methods

by APHIS Wildlife Services

Chapter XXIX

USE OF MINIMUM RISK PESTICIDES

IN WILDLIFE DAMAGE MANAGEMENT

Draft

September 2023
ii

EXECUTIVE SUMMARY

Minimum risk pesticides (MRPs) are a specific group of substances that the U.S. Environmental 

Protection Agency (USEPA) has determined pose little to no risk to human health or the 

environment and are used in preventing, destroying, repelling, or mitigating pests. MRPs that 

meet the requirements under Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) 

Section 25(b) and 40 CFR 152.25(f) are exempt from the requirement for federal registration with 

USEPA. However, the pesticide laws in many states still require registration of MRPs by the state 

pesticide regulatory agency before distribution and use in that state.

If a pesticide product does not meet all exemption criteria under 40 CFR 152.25(f), then 

registration is required with USEPA unless the pesticide product is otherwise exempt from 

registration requirements. For example, when MRP active ingredients are combined with any

substances not allowed in MRPs under 40 CFR 152.25(f) (active or inert ingredients), the product 

requires federal registration under FIFRA. The United States Department of Agriculture (USDA), 

Animal and Plant Health Inspection Service (APHIS) discussed MRP active ingredients that are 

contained within registered pesticides in the Registered Chemical Repellents Risk Assessment 

(Chapter XXIV) and Egg Addling Risk Assessment (Chapter XVI).

USDA APHIS Wildlife Services (WS) uses or may use MRPs to reduce bird conflicts and damage 

to crops and property and reduce mammal damage to gardens, crops, trees, and property. Many 

MRPs mitigate pests by altering the pest's behavior (e.g., a repellent), but some may be used as 

toxicants or contraceptives for pests. Flocking passerine bird species such as European starlings, 

blackbirds, and flocking waterbirds, such as gulls, Canada geese, and cormorants, are the 

primary target bird species WS repel or control with MRPs. WS also uses MRPs to repel pest 

mammal species like feral house cats, white-tailed deer, and rabbits.

APHIS evaluated the potential human health and ecological risks from the proposed WS use of 

the MRP active ingredients cloves, corn oil, dried blood, garlic and garlic oil, potassium sorbate, 

putrescent whole egg solids, sodium lauryl sulfate, and thyme oil. WS does not anticipate adverse 

human health effects from their use of MRPs based on the FIFRA Section 25(b) requirements for 

MRPs, the WS use pattern, and the lack of significant human health and environmental hazards 

posed by the MRP active ingredients. Adherence to WS personal protective equipment 

requirements minimizes potential exposure to workers. 
iii

Table of Contents

GLOSSARY OF TERMS AND ABBREVIATIONS..........................................................vii

1 INTRODUCTION.......................................................................................................... 1

1.1 WS Use Pattern................................................................................................................ 3

2 CLOVES....................................................................................................................... 5

2.1 Problem Formulation ........................................................................................................ 5

2.1.1 Chemical Description and Product Use...................................................................... 5

2.2 Dose-Response Assessment............................................................................................ 6

2.2.1 Human Health Dose-Response.................................................................................. 6

2.2.2 Ecological Effects Dose Response............................................................................. 7

2.3 Exposure Assessment and Risk Characterization............................................................. 8

2.3.1 Human Health Exposure and Risk Characterization................................................... 8

2.3.2 Ecological Exposure and Risk Characterization ......................................................... 9

3 CORN OIL.................................................................................................................... 9

3.1 Problem Formulation ........................................................................................................ 9

3.1.1 Chemical Description and Product Use...................................................................... 9

3.1.2 Physical and Chemical Properties.............................................................................. 9

3.1.3 Environmental Fate .................................................................................................... 9

3.1.4 Hazard Identification .................................................................................................10

3.2 Dose-Response Assessment...........................................................................................10

3.2.1 Human Health Dose-Response.................................................................................10

3.2.2 Ecological Effects Dose Response............................................................................10

3.3 Exposure Assessment and Risk Characterization............................................................10

3.3.1 Human Health Exposure and Risk Characterization..................................................10

3.3.2 Ecological Exposure and Risk Characterization ........................................................10

4 DRIED BLOOD........................................................................................................... 10

4.1 Problem Formulation .......................................................................................................10

4.1.1 Chemical Description and Product Use.....................................................................10

4.1.2 Physical and Chemical Properties.............................................................................11

4.1.3 Environmental Fate ...................................................................................................11

4.1.4 Hazard Identification .................................................................................................11

4.2 Dose-Response Assessment...........................................................................................11
iv

4.2.1 Human Health Dose-Response.................................................................................11

4.2.2 Ecological Effects Dose Response............................................................................12

4.3 Exposure Assessment and Risk Characterization............................................................12

4.3.1 Human Health Exposure and Risk Characterization..................................................12

4.3.2 Ecological Exposure and Risk Characterization ........................................................12

5 GARLIC AND GARLIC OIL ........................................................................................ 12

5.1 Problem Formulation .......................................................................................................12

5.1.1 Chemical Description and Product Use.....................................................................12

5.1.2 Physical and Chemical Properties.............................................................................13

5.1.3 Environmental Fate ...................................................................................................13

5.1.4 Hazard Identification .................................................................................................13

5.2 Dose-Response Assessment...........................................................................................14

5.2.1 Human Health Dose-Response.................................................................................14

5.2.2 Ecological Effects Dose Response............................................................................14

5.3 Exposure Assessment and Risk Characterization............................................................14

5.3.1 Human Health Exposure and Risk Characterization..................................................14

5.3.2 Ecological Exposure and Risk Characterization ........................................................14

6 POTASSIUM SORBATE............................................................................................ 14

6.1 Problem Formulation .......................................................................................................14

6.1.1 Chemical Description and Product Use.....................................................................14

6.1.2 Physical and Chemical Properties.............................................................................15

6.1.3 Environmental Fate ...................................................................................................15

6.1.4 Hazard Identification .................................................................................................15

6.2 Dose-Response Assessment...........................................................................................16

6.2.1 Human Health Dose-Response.................................................................................16

6.2.2 Ecological Effects Dose Response............................................................................16

6.3 Exposure Assessment and Risk Characterization............................................................17

6.3.1 Human Health Exposure and Risk Characterization..................................................17

6.3.2 Ecological Exposure and Risk Characterization ........................................................17

7 PUTRESCENT WHOLE EGG SOLIDS...................................................................... 17

7.1 Problem Formulation .......................................................................................................17

7.1.1 Chemical Description and Product Use.....................................................................17

7.1.2 Physical and Chemical Properties.............................................................................18
v

7.1.3 Environmental Fate ...................................................................................................18

7.1.4 Hazard Identification .................................................................................................18

7.2 Dose-Response Assessment...........................................................................................18

7.2.1 Human Health Dose Response.................................................................................18

7.2.2 Ecological Effects Dose-Response............................................................................19

7.3 Exposure Assessment and Risk Characterization............................................................19

7.3.1 Human Health Exposure and Risk Characterization..................................................19

7.3.2 Ecological Exposure and Risk Characterization ........................................................20

8 SODIUM LAURYL SULFATE (SLS)........................................................................... 20

8.1 Problem Formulation .......................................................................................................20

8.1.1 Chemical Description and Product Use.....................................................................20

8.1.2 Physical and Chemical Properties.............................................................................20

8.1.3 Environmental Fate ...................................................................................................20

8.1.4 Hazard Identification .................................................................................................21

8.2 Dose-Response Assessment...........................................................................................21

8.2.1 Human Health Dose-Response.................................................................................21

8.2.2 Ecological Effects Dose Response............................................................................22

8.3 Exposure Assessment and Risk Characterization............................................................23

8.3.1 Human Health Exposure and Risk Characterization..................................................23

8.3.2 Ecological Exposure and Risk Characterization ........................................................23

9 THYME OIL................................................................................................................ 25

9.1 Problem Formulation .......................................................................................................25

9.1.1 Chemical Description and Product Use.....................................................................25

9.1.2 Physical and Chemical Properties.............................................................................25

9.1.3 Environmental Fate ...................................................................................................25

9.1.4 Hazard Identification .................................................................................................25

9.2 Dose-Response Assessment...........................................................................................25

9.2.1 Human Health Dose-Response.................................................................................25

9.2.2 Ecological Effects Dose Response............................................................................26

9.3 Exposure Assessment and Risk Characterization............................................................27

9.3.1 Human Health Exposure and Risk Characterization..................................................27

9.3.2 Ecological Exposure and Risk Characterization ........................................................27

10 UNCERTAINTIES AND CUMULATIVE IMPACTS................................................... 27
vi

11 SUMMARY............................................................................................................... 28

12 LITERATURE CITED ............................................................................................... 29

13 PREPARERS: WRITERS, EDITORS, AND REVIEWERS....................................... 33

13.1 APHIS WS Methods Risk Assessment Committee ........................................................33

13.2 Internal Reviewers.........................................................................................................34

APPENDIX TABLE A.1 ................................................................................................. 36

List of Tables

Table 1. The annual average number of gallons or pounds of minimum risk pesticides 

(MRPs) applied or distributed by APHIS-WS in WDM activities in FY16–FY20 and the 

number of work tasks (WTs) associated with the applications or distributions................ 4

Table 2. The annual average number of eggs treated, amounts of corn oil applied, and 

the number of states for each target bird species in WDM activities by APHIS-WS in 

FY16–FY20. .................................................................................................................... 5

Table 3. Acute oral median lethality studies for mammals for cloves and clove oil. ........ 7

Table 4. Acute and chronic toxicity to aquatic vertebrates and invertebrates for clove oil.

........................................................................................................................................ 8

Table 5. Acute and chronic toxicity to aquatic vertebrates and invertebrates for SLS... 24
vii

GLOSSARY OF TERMS AND ABBREVIATIONS

μg Microgram

bw Body weight

CAS Chemical Abstract Service

EC50 Median effect concentration. A statistically derived concentration of a substance 

that can be expected to cause an effect in 50% of test organisms. It is usually 

expressed as a weight of a substance per weight or volume of water or air, e.g., 

mg/L.

FDA Food and Drug Administration

FY The federal Fiscal Year, which is October 1–September 30.

g Gram

GRAS Generally Recognized as Safe

kg Kilogram

kg-bw Kilogram of body weight

lb Pound

L Liter

LC50 Median lethal concentration. A statistically derived concentration of a substance 

that can be expected to cause death in 50% of test animals. It is usually expressed 

as a weight of a substance per weight or volume of water, air or feed, e.g., mg/L, 

mg/kg-bw.

LD50 Median lethal dose. A statistically derived single dose that can be expected to 

cause death in 50% of the test animals when administered by the route indicated 

(oral, dermal, inhalation). It is expressed as a weight of substance per unit weight 

of animal, e.g., mg/kg.

mg Milligram

mm Hg Millimeter of mercury

NOAEL No observed adverse effect level. The highest dose level of a substance that under 

defined conditions of exposure causes no observable/detectable adverse effect.

OPP Office of Pesticide Programs, USEPA

PPE Personal protective equipment

Tolerance Maximum amount of pesticide residues allowed on or in food or feed.
viii

USEPA U.S. Environmental Protection Agency

WDM Wildlife damage management

WT Work tasks

w/w Weight by weight
1

1 INTRODUCTION

The U.S. Department of Agriculture (USDA), Animal and Plant Health Inspection Service (APHIS), 

Wildlife Services (WS) employees conduct wildlife damage management (WDM) activities, which 

include the use of Minimum Risk Pesticides (MRPs) as WDM tools. Pesticides are substances or 

mixtures of substances intended for preventing, destroying, repelling, or mitigating any pest 

according to Section 2(u) of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).

MRPs are pesticides that the U.S. Environmental Protection Agency (USEPA) has determined 

pose little to no risk to human health or the environment. MRPs that meet the requirements under 

FIFRA Section 25(b) and 40 CFR 152.25(f) are exempt from the requirement for federal 

registration with USEPA prior to distribution, sale, and use. Exemption of these products reduces 

the cost and regulatory burden on businesses and the public for pesticides posing little or no risk. 

To qualify as exempt from the requirements for federal registration with USEPA, MRPs must meet 

the following six conditions specified by USEPA (2023d): 1) only contain active ingredients listed 

in 40 CFR 152.25(f)(1); 2) only contain inert ingredients listed in 40 CFR 152.25(f)(2), commonly 

consumed food items in 40 CFR 180.950(a), animal feed items in 40 CFR 180.950(b), edible fats 

and oils in 40 CFR 180.950(c), or substances listed under 40 CFR 180.950(e); 3) list all 

ingredients by label display name and list the active ingredients' percentages by weight on the 

product label; 4) the product labeling cannot claim to control or mitigate organisms that pose a 

threat to human health or insects or rodents carrying specific diseases; 5) provide the name and 

contact information of the producer on the label; and 6) the labeling cannot contain any false or 

misleading statements. Some MRP products cannot be applied to growing or edible portions of 

agricultural crops because the product may damage the crop, make the plant unpalatable for 

human consumption, or if one or more of the ingredients are not approved for food or feed uses.

Each state has statutes and regulations for pesticides, including requirements for the registration, 

distribution, sale, and use of MRPs. Many state pesticide laws require state registration of MRPs 

before distributing or selling an MRP in their state. In states requiring state registration of MRPs, 

WS may use MRPs already registered or register additional MRPs with the state for their WDM 

activities. Under FIFRA and many state pesticide laws, the term "distribute or sell" regarding a 

pesticide includes the application of a pesticide by an applicator to someone else's property (i.e., 

providing a service of controlling pests using a pesticide substance) (USEPA 2009a). 

MRPs come in various commercial "ready-to-use" and concentrate products and are labeled in 

accordance with 40 CFR 152.25(f) and state pesticide laws and regulations in the states where 

state registration is required. MRPs are classified as general-use pesticides by USEPA, which 

can be applied without a certified applicator license in most states and U.S. territories. However, 

some states and territories require commercial and public pesticide applicators are licensed by 

the state before applying general-use products on other public property.

WS may use MRPs to manage wildlife that cause damage to property, agriculture, and natural 

resources or are potential threats to public safety. WS uses MRP repellents similarly to federally 

registered chemical repellents to prevent damage to gardens, crops, trees, and property from pest 

mammals and birds. Federally registered chemical repellents are covered in another risk 
2

assessment 1 . The successful application of MRP repellents to target specific pest animals 

requires knowledge that 1) MRPs are often, but not always, used to deter animal activity while 

not causing permanent harm or injury to animals and may require continual training with 

populations that turn over frequently; 2) the target animal has the sensory abilities to detect and 

respond to the MRP's active ingredient(s); and 3) MRPs are exempt from the requirement for 

federal registration under Section 25(b) of FIFRA and meet any other federal and state regulatory 

requirements for pesticides.

In recent years, WS has used or distributed MRP products containing the following active 

ingredients: cloves (flower buds of Syzygium aromaticum), corn (Zea mays) oil, dried blood, garlic

(Allium sativum) or garlic oil, potassium sorbate, putrescent whole egg solids (i.e., egg solids), 

sodium lauryl sulfate (SLS), and thyme (Thymus spp.) oil. The primary target bird species WS 

controlled or repelled with these MRPs were flocking passerine bird species (e.g., European 

starlings2 and blackbirds3), gulls, waterfowl, and double-crested cormorants. White-tailed deer, 

rabbits, and feral cats were the primary target mammal species.

A few MRPs are used in the population control of particular wildlife. One MRP that WS has used

is SLS, an avian wetting agent used to manage flocking starling and blackbird species in roosts 

via a spray system (USDA 2021). When applied to birds during low temperatures (less than 5°C 

or 41°F) and sufficient precipitation, SLS allows water to penetrate and saturate their feathers so 

that treated birds die of hypothermia. (USDA 2021). Another WDM method WS applies is egg 

oiling (corn oil), primarily used for waterbirds. Corn oil is applied to eggs in individual nests with a 

cloth or sprayer to clog egg pores, which prevents oxygen from entering the egg and asphyxiates

the developing embryo (USDA 2001). Egg addling by egg oiling as a WDM tool was discussed in 

the Egg Addling Risk Assessment4 in addition to two other mechanical egg addling methods. The 

risk assessment primarily discussed using corn oil as a WDM method but did not evaluate corn 

oil's human health and ecological risks.

This human health and ecological risk assessment provides a qualitative evaluation of risks and 

hazards of the MRPs WS proposes to use on human health and the environment, including 

nontarget fish and wildlife. The methods used to assess potential human health effects follow 

standard regulatory guidance and methodologies (National Research Council 1983) and 

generally conform to other Federal agencies such as the USEPA (USEPA 2022a). The methods 

used to assess potential ecological risk to nontarget fish and wildlife generally follow USEPA 

(2022a) methodologies.

1 Risk assessment on the use of registered chemical repellents in wildlife damage management is found at 

https://www.aphis.usda.gov/aphis/ourfocus/wildlifedamage/programs/nepa/ct-ws-risk_assessments. 2 Scientific names are given in the Risk Assessment Introduction Chapter I, unless first time used.

3 Generic use of blackbirds for this risk assessment includes specific species of blackbirds, cowbirds, and 

grackles.

4 Risk assessment on the use of egg addling in wildlife damage management is found at 

https://www.aphis.usda.gov/aphis/ourfocus/wildlifedamage/programs/nepa/ct-ws-risk_assessments.
3

1.1 WS Use Pattern

The primary formulations that WS used in FY16-FY20 are given in Table 1, providing the quantity 

of each MRP applied and distributed and the associated number of work tasks. Data for FY11-

FY15 are provided in Appendix 1.

During FY16–FY20, WS used MRPs in 33 states. The most common MRP used was corn oil to 

addle an annual average of 39,903 eggs of gulls, double-crested cormorants, Canada geese, 

American white pelicans, and other bird species (Table 2). Sodium lauryl sulfate was used in 

Washington to manage starling damage by removing an annual average of 1,480 starlings. WS 

also applied Bonide® Repels-All granules and Liquid formulations to repel feral cats and Liquid 

Fence to repel deer and rabbits. WS State Offices and personnel also provide the public with 

some MRP products for their own use, mostly in cooperation with state agencies that manage 

game animals, such as white-tailed deer, to lessen problems for farmers and property owners 

from their damage. Of the 20 average annual work tasks (WTs) associated with distributing 

repellents from FY11–FY20, WS responded to public requests involving white-tailed deer (94.1% 

of WTs), Canada geese (2.9%), eastern cottontail rabbits (1%), house sparrows (1%), 

woodchucks (0.5%), and wild turkeys (0.5%).

WS uses or distributes the MRP active ingredients covered in this risk assessment: corn oil, 

cloves, dried blood, putrescent whole egg solids (aka, egg solids), garlic/garlic oil, potassium 

sorbate, SLS, and thyme oil. A problem formulation, dose-response assessment, exposure 

assessment, and risk characterization are provided below for each registered active ingredient 

used or potentially used by WS in the future. The problem formulation section covers each 

registered active ingredient's chemical description, product use, physical and chemical properties, 

environmental fate, and hazard identification. Environmental fate describes how chemicals move 

and degrade in the environment. The environmental fate processes include 1) persistence, 

degradation, and mobility in soil; 2) movement to air; 3) migration potential to groundwater and 

surface water; 4) degradation in water; and 5) plant uptake.

The dose-response assessment section discusses the dose levels (toxicity criteria) for potential 

human health effects, including acute and chronic toxicity. It also discusses available ecological 

effects data for terrestrial and aquatic species. Available acute and chronic toxicity data are 

summarized for all major taxa. This data will be integrated with the exposure analysis section to 

characterize the risk of chemical repellents to nontarget species. This section gathered 

information from online databases and searches for relevant peer-reviewed and other published 

literature.

Unless otherwise specified, the toxicity of the technical active ingredient for nontarget mammals 

and birds was assumed to be similar to the toxicity of the end-use formulations, which is a 

conservative approach. The toxicity of degradants and metabolites of the chemical repellents to 

nontarget species are unknown but are assumed to be similar to the parent chemicals for this risk 

assessment.
4

Table 1. The annual average number of gallons or pounds of minimum risk pesticides (MRPs) applied or distributed by APHIS-WS in 

WDM activities in FY16–FY20 and the number of work tasks (WTs) associated with the applications or distributions.

*See Table 2 for specifics of corn oil applications, including species and states used.

Active Ingredient(s) 

(%w/w, CAS Number) Product Applied (gal/lb) WTs States Used

Distributed 

(gal/lb) WTs States Used

Putrescent Whole Egg Solids 

(1.12%; 51609-52-0)

Cloves (0.54%; N/A)

Garlic Oil (0.03%; 8000-78-0)

Shot-Gun® Repels-All®

(granules, Bonide®

Products LLC)

1.8 lb 1 PA 0.6 lb 1 PA

Putrescent Whole Egg Solids 

(1.01%; 51609-52-0)

Cloves (0.05%; N/A)

Garlic Oil (0.02%; 8000-78-0)

Shot-Gun® Repels-All®

(liquid, Bonide® Products 

LLC)

0.5 gal 1 PA - - -

Putrescent Whole Egg Solids 

(1.040%; 51609-52-0)

Garlic (0.374%; N/A)

Sodium Lauryl Sulfate (0.040%; 

151-21-3)

Potassium Sorbate (0.495%; 

24634-61-5)

Thyme Oil (0.010%; 8007-46-3)

Liquid Fence® Deer & 

Rabbit Repellent

(liquid, The Liquid Fence 

Co., now Spectrum Brands, 

Inc.)

1 gal 1 NH 2.2 gal 3.2 NH

Dried Blood (12.0%; 68911-49-9)

Plantskydd® Repellent

(liquid, Tree World® Plant 

Care Products Inc.)

- - - 0.6 gal 2.4 NH

Dried Blood (100%; 68911-49-9)

Plantskydd® Repellent 

(powder concentrate, Tree 

World® Plant Care Products 

Inc.)

- - - 63.8 lb 7 NH/WI

Sodium Lauryl Sulfate (28–30%; 

151-21-3) Multiple 7.8 gal 2.2 WA - - -

Corn Oil (100%; 8001-30-7) Multiple 35 gal 722 32* - - -
5

Table 2. The annual average number of eggs treated, amounts of corn oil applied, and the number 

of states for each target bird species in WDM activities by APHIS-WS in FY16–FY20.

Species Eggs Estimated Corn Oil 

(oz)1

States

Used

Canada Goose 6,892 985 29 + DC

Mute Swan* 336 67 4

Mallard 51 4 8

Mourning Dove 0.4 0.03 1

Black-necked Stilt 2 0.1 1

American Avocet 5 0.4 1

Killdeer 3 0.2 2

Laughing Gull 2,249 161 1

Ring-billed Gull 17,995 1,285 6

Herring Gull 1,161 83 6

Glaucous-winged Gull 963 69 1

Great Black-backed Gull 17 1 1

American White Pelican 1,039 148 1

Double-crested Cormorant 9,188 656 4

Osprey 1 0.1 1

American Robin 1 0.1 1

Total 39,903 3,460 1 Ounces of corn oil used was estimated at 14 eggs oiled per ounce of corn oil (~2 mL) for birds similar in size to 

chickens (gulls, mallards, cormorants, and other), which is slightly more than the 2 mL/egg used by Pochop et al. 

(1998), 4 mL/egg (7 eggs/oz) for larger birds (goose and pelican), and 6 mL/egg (about 5 eggs/oz) for swans, based 

on egg surface areas, which for swans is about three times that of a chicken).

* Introduced species

The exposure assessment section evaluates the potential for exposure of humans to the chemical 

repellents WS applies. The exposure assessment begins with the WS use pattern for chemical 

repellents. An exposure pathway for chemical repellents includes (1) a release from a chemical 

repellent source, (2) an exposure point where contact can occur, and (3) an exposure route such 

as ingestion, inhalation, or dermal contact by which contact can occur. Exposures for the identified 

human populations are evaluated qualitatively for each identified exposure pathway. Risks 

associated with adverse human health are characterized qualitatively in this section. The 

ecological exposure potential and risk characterization for each repellent are also discussed. In 

cases where data is lacking, USEPA assumes that avian toxicity data is representative of reptiles 

and terrestrial-phase amphibians, and fish toxicity data is representative of aquatic-phase 

amphibians.

2 CLOVES

2.1 Problem Formulation

2.1.1 Chemical Description and Product Use

Cloves (CAS number N/A) are the aromatic dried flower buds of the evergreen tree Syzygium 

aromaticum, native to Southeast Asia. Clove oil can be produced from the tree's flower buds or 

other plant parts (e.g., leaves, stems). Clove oil's primary constituent is the terpenoid eugenol 
6

(CAS number 97-53-0). Cloves and clove oil have a sharp phenolic smell and strong acrid taste 

that work to deter and prevent feeding by some species of mammals (rabbits and deer).

The MRP products that WS uses containing cloves include other MRP active ingredients in their 

formulation, which are covered separately in this risk assessment. WS may use and distribute 

MRP products containing cloves to cooperators to deter herbivores from browsing.

2.1.2 Physical and Chemical Properties

Clove powder is light tan to brown in color, while clove oil is colorless to pale yellow. Clove oil and 

powder have a sharp odor and are insoluble in water. Clove oil has a boiling point of 251°C 

(Sigma-Aldrich Corporation 2023a). It has a vapor pressure of 4.91x10-6 mm Hg (Baker et al. 

2018). Clove oil has a density of 1.038–1.060 g/cm3 at 25°C (Merck 2023). It has an 

octanol/water coefficient of log Kow of 0.99 (Baker et al. 2018).

2.1.3 Environmental Fate

Cloves and clove oil have a soil half-life of 21.5 hours, an air half-life of 0.01 hours, and a water 

half-life of 78.4 hours, indicating low to no environmental persistence (Baker et al. 2018).

2.1.4 Hazard Identification

Cloves and their derivatives, including clove oil, are classified as Generally Recognized as Safe 

(GRAS) by the U.S. Food and Drug Administration (FDA) when used as food additives (21 CFR 

184.1257). Cloves and clove oil are exempt from the requirement of a tolerance in or on all food 

and feed crops when used as a pesticide active ingredient or inert ingredient under 40 CFR 

180.1164(d) because it is considered a commonly consumed food commodity (Baker et al. 2018).

A National Pesticide Information Center (NPIC) database review identified 19 reported incidents 

associated with clove and clove oil use between 1996 and 2016, or about one annually. None of 

the incidents were serious, and most involved formulated products with multiple ingredients 

(Baker et al. 2018).

2.2 Dose-Response Assessment

2.2.1 Human Health Dose-Response

Acute Toxicity

Clove and clove oil have low to no toxicity to mammals through all routes of exposure (Table 3).

Cloves and clove oil have minimal to no human health hazards. In closed-patch tests on human 

skin, clove bud oil applied at a rate of 20% weight by weight (w/w) in Vaseline or ointment caused 

primary irritation or erythema in 2 out of 25 human subjects. However, 2% and 5% clove bud oil 

did not cause any reactions in human subjects (Opdyke 1975a;b). Cloves are a commonly 

consumed food commodity with a significant history of human exposure, demonstrating minimal 

toxicity. 
7

Table 3. Acute oral median lethality studies for mammals for cloves and clove oil.

Test Species Test Result

USEPA 

Toxicity 

Category

Reference

Albino Wistar Rat 

(male) Acute Oral LD50 Flower oil: 3,598 mg/kgbw III (Shalaby et al. 2011)

Laboratory Brown Rat Acute Oral LD50 Leaf oil: 1,370 mg/kg-bw III (Opdyke 1978)

Laboratory Brown Rat Acute Oral LD50 Bud oil: 2,650 mg/kg-bw III (Opdyke 1975a)

Laboratory Brown Rat Acute Oral LD50

Stem oil: 2,020 mg/kgbw III (Opdyke 1975b)

Domestic Rabbit Acute Dermal 

LD50

Leaf oil: 1,200 mg/kg-bw III (Opdyke 1978)

Domestic Rabbit Acute Dermal 

LD50

Bud oil: >5,000 mg/kgbw IV (Opdyke 1975a)

Domestic Rabbit Acute Dermal 

LD50

Stem oil: >5,000 mg/kgbw IV (Opdyke 1975b)

Domestic Rabbit Primary Dermal 

Irritation Moderately irritating III (Opdyke 

1975a;1978)

Laboratory Mouse Primary Dermal 

Irritation

Not irritating to severely 

irritating II-IV (Opdyke 

1975a;1978)

Subchronic and Chronic Toxicity

Albino male Wistar rats gavaged with clove oil at 10% of the LD50 (~360 mg/kg-bw) for one month 

were found to have liver inflammation and renal corpuscular tubules that were convoluted and 

hemorrhaging in the interstices of the kidneys (Shalaby et al. 2011). 

No chronic toxicity studies of clove and clove oil were found.

Developmental and Reproductive Effects, Neurotoxicity Effects, Carcinogenicity and 

Mutagenicity, Immunotoxicity Effects, and Endocrine Effects

Cloves and clove oil are not classified as carcinogens by the International Agency for Research 

on Cancer (IARC) (IARC 2023). Prenatal developmental toxicity studies showed no difference 

between treated and control groups of rats, mice, hamsters, and rabbits (Baker et al. 2018). Clove 

oil is highly cytotoxic to human fibroblasts at concentrations as low as 0.03% w/w. The cytotoxic 

effect is attributed to eugenol, the main chemical component of clove oil (Prashar et al. 2006).

2.2.2 Ecological Effects Dose Response

Aquatic Effects Analysis

Clove oil is slightly toxic to freshwater fish and aquatic invertebrates (Table 4).
8

Table 4. Acute and chronic toxicity to aquatic vertebrates and invertebrates for clove oil.

Taxonomic 

group Test species Test Result Reference

Freshwater 

Fish

Rainbow trout

(Oncorhynchus mykiss) 10-min LC50 81.1 mg/L (Velisek et al. 2005a)

Freshwater 

Fish

Rainbow trout

(Oncorhynchus mykiss) 30-min LC50 65.0 mg/L (Velisek et al. 2005a)

Freshwater 

Fish

Rainbow trout

(Oncorhynchus mykiss) 24-hr LC50 61.5 mg/L (Velisek et al. 2005a)

Freshwater 

Fish Carp (Cyprinus carpio) 96-hr LC50 74.3 mg/L (Velisek et al. 2005b)

Freshwater 

Fish Zebrafish (Danio rerio) 96-hr LC50 18.2 mg/L (Doleželová et al. 2011)

Freshwater 

Fish

Guppy (Poecilia 

reticulate) 96-hr LC50 21.7 mg/L (Doleželová et al. 2011)

Freshwater 

Invertebrates

Gammarus (Gammarus 

minus) EC50 >14.7 μl/ml (Venarsky and Wilhelm 2006)

Terrestrial Effects Analysis

No acute oral median lethality or subacute dietary toxicity studies for mammals or birds were 

found for cloves or clove oil. Clove oil was not toxic to western honey bees (Apis mellifera) at a 

dose of 1 mg/bee over a 48-hr period (Lindberg et al. 2000). In another study, the 8-day oral LD50

for clove oil was estimated to be reached with a 7,800 ppm solution. The 14-day oral LD50 was

estimated to be reached with a 240 ppm solution for honey bees (Ebert et al. 2007). The American 

Society for the Prevention of Cruelty to Animals Animal Poison Control Center reported that 

between 2006 and 2008, 39 cats and nine dogs were involved in exposure incidents with flea 

products that contained clove oil and other active ingredients exempt from federal registration

(Genovese et al. 2012). Symptoms included skin erythema, vomiting, diarrhea, lethargy, edema, 

ataxia, seizures, weakness, recumbent tachycardia, agitation, anorexia, hyperactivity, 

hypersalivation, panting, retching, tremors, vocalization, and renal failure. Clove oil can be used 

as an herbicide and exhibits phytotoxicity. Studies have shown leaf injury to dandelion 

(Taraxacrum officinale) at a 2% w/w concentration (Tworkoski 2002) and 8% w/w concentrations 

of clove oil caused plant injury to common lambsquarters (Chenopodium album), common 

ragweed (Ambrosia artemesiifolia), and johnsongrass (Sorghum halepense) (Tworkoski 2002). 

No studies on the effects on nontarget plants were found.

2.3 Exposure Assessment and Risk Characterization

2.3.1 Human Health Exposure and Risk Characterization

The annual amount of cloves that WS uses in its wildlife damage management program is limited 

(Table 1). Between FY16 and FY20, WS only used an average of 1.8 pounds of MRPs containing 

0.54% w/w of the active ingredient cloves. Cloves pose little to no risk to human health from this 

use. Applications of products containing cloves as active ingredients applied according to label 

instructions should not result in harm to the general population or applicators. Due to the low 

toxicity of cloves and clove oil to humans or mammals, the low volumes of MRP products 
9

containing cloves that WS uses, and the training of WS applicators in the proper use of personal 

protection equipment (PPE) and pesticides, the risks to WS applicators or the public from WS use 

or distribution of MRP repellent products containing cloves are negligible.

2.3.2 Ecological Exposure and Risk Characterization

Cloves pose little to no risk to the environment. WS applicators adhere to label requirements, 

which include not applying the product directly to water. Based on the limited use, small quantities 

of cloves in the formulated products, the lack of toxicity, and the environmental fate properties, 

WS use of formulated products containing cloves will not harm nontarget terrestrial and aquatic 

species.

3 CORN OIL

3.1 Problem Formulation

3.1.1 Chemical Description and Product Use

Corn oil (CAS number 8001-30-7) is a commonly consumed food ingredient (21 CFR 101). Corn 

oil is extracted from corn kernels from corn plants, usually using a wet milling process (Baker and 

Grant 2018a). Corn oil is primarily composed of the glycerides of linoleic acid (34–62% w/w),

followed by oleic acid (19–49% w/w), palmitic acid (8–12% w/w), stearic acid (2.5–4.5% w/w),

and hexadecenoic and myristic acids (0.1–1.7% w/w each) (Merck 2023). Corn oil is highly 

digestible (Baker and Grant 2018a). In addition to being an MRP active ingredient, corn oil is an 

inert commodity ingredient in registered pesticides (USEPA 2023b).

WS may use MRP products containing 100% w/w corn oil to addle eggs of pest bird species, 

primarily waterbirds (Tables 1 and 2). Corn oil is applied to the surface of pest bird species eggs 

during incubation, which closes the eggshell’s surface pores and asphyxiates the developing 

embryo (Baker and Grant 2018a, USDA 2001). Additional information on the uses of corn oil for 

egg addling is available in the Egg Addling Risk Assessment.

3.1.2 Physical and Chemical Properties

Corn oil is a yellow liquid with a characteristic corn odor (Merck 2015). Corn oil solidifies at -18–

-10°C, boils (smokes) at 230–238°C, is insoluble in water, and is slightly soluble in alcohol 

(Merck 2023, NIH 2023c). Corn oil has a density of 0.916–0.921 g/cm3 at 25°C (Merck 2023)

and a vapor pressure of 3.18x10-11,

and an octanol/water coefficient (Kow) of 1.86 (Baker and Grant 

2018a). 

3.1.3 Environmental Fate

Corn oil has a half-life in soil of 2,880 hours, a half-life in air of 0.276 hours, and a half-life in water 

of 1,440 hours, indicating environmental persistence. Corn oil is readily biodegradable (Baker and 

Grant 2018a).
10

3.1.4 Hazard Identification

Corn oil is a commonly consumed food ingredient (21 CFR 101). Corn oil is exempt from the 

requirement of a tolerance in or on all food commodities when used as a pesticide active 

ingredient or inert ingredient under 40 CFR 180.950(c) as an edible oil (Baker and Grant 2018a).

No human health incidents involving corn oil were reported to NPIC between 1996 and 2016

(Baker and Grant 2018a).

3.2 Dose-Response Assessment

3.2.1 Human Health Dose-Response

Corn oil is classified as nontoxic for acute and 90-day oral toxicity (Andersen et al. 2011, Baker 

and Grant 2018a, Sigma-Aldrich Corporation 2023b). Corn oil causes slight, reversible eye 

irritation and is a mild dermal irritant, but it is not a skin sensitizer (Andersen et al. 2011, Baker 

and Grant 2018a, Sigma-Aldrich Corporation 2023b). Corn oil does not cause reproductive or 

developmental toxicity (Baker and Grant 2018a). Corn oil is classified as an equivocal carcinogen 

in the Hazardous Substances Database when consumed in relatively high doses (10 ml/kg-bw)

(Baker and Grant 2018a).

3.2.2 Ecological Effects Dose Response

No data are available on the ecotoxicity of corn oil. Corn oil is a suffocating oil (physical 

mechanism of control) when applied to the surface of insects, blocking the insects' spiracles 

(Baker and Grant 2018a).

3.3 Exposure Assessment and Risk Characterization

3.3.1 Human Health Exposure and Risk Characterization

Corn oil has minimal human health hazards, is a commonly consumed food ingredient, and has 

a significant history of exposure to humans, demonstrating minimal toxicity (Baker and Grant 

2018a). The use of MRP products containing corn oil by WS for egg addling poses minimal to no

risk to the general public or WS applicators.

3.3.2 Ecological Exposure and Risk Characterization

WS's low-use volumes for egg addling, the lack of oral toxicity to mammals, and the 

biodegradability of corn oil indicate MRP repellents containing corn oil pose little to no exposure 

risk to nontarget terrestrial or aquatic species.

4 DRIED BLOOD

4.1 Problem Formulation

4.1.1 Chemical Description and Product Use

Dried blood (CAS Number 68911-49-9) is produced from clean, fresh bovine or porcine blood 

obtained from slaughterhouses (USEPA 1991). The raw blood is flash dried, centrifuged, and then 

thoroughly dried at very high temperatures. Dried blood is the active ingredient in MRP-repellent 

products for various pest mammals (deer, rabbit, squirrel, vole, elk, moose). Dried blood products 
11

can be used to protect agriculture (fruiting trees, nurseries, crops), forestry (Trent et al. 2001), 

and personal landscaping and gardens. Dried blood is also a non-food use only inert ingredient 

in registered pesticides (USEPA 2023b).

Dried blood is a naturally occurring substance and has a nontoxic mode of action. Dried blood 

can be applied as a perimeter treatment to protect an area or as a contact treatment applied 

directly to the plant (Trent et al. 2001). Formulated products that contain dried blood are 100%

w/w dried blood and available in "ready-to-use" granules or liquid formulations. Granules are 

placed or sprinkled by hand on the ground. Liquid formulations may be sprayed onto the trunks 

of trees or used as a dip for bulbs or tree whips. WS distributes dried blood products to 

cooperators experiencing deer and rabbit damage (Table 1).

4.1.2 Physical and Chemical Properties

Dried blood is a black and tan speckled powder with a faint odor (Baker and Grant 2018e). It is 

stable when stored in sealed containers at ambient temperatures. 

4.1.3 Environmental Fate

Dried blood is organic matter that rapidly degrades in the environment.

4.1.4 Hazard Identification

USEPA determined that potential risks to humans from exposure to dried blood pesticide products 

during application are considered negligible, and the MRP uses of dried blood alone pose no 

adverse human health effects. The manufacturing process ensures the denaturation of 

proteinaceous material and inactivation of potential mammalian pathogens (i.e., endogenous or 

exogenous contaminants) in dried blood used as a repellent (USEPA 1991).

Dried blood does not have a tolerance or an exemption from the tolerance requirement in 40 CFR 

180 and cannot be used on food crops (Baker and Grant 2018e). Dried blood is not classified as

GRAS by FDA as a food additive. Blood and blood products are excluded from the prohibition of 

animal-derived protein sources in livestock feed (21 CFR 589.2000) (Baker and Grant 2018e).

The National Pesticide Information Center (NPIC) received 21 reports of human health-related 

incidents between 1996 and 2016 (Baker and Grant 2018e). Symptoms included headaches, 

sweating, gagging, nausea, vomiting, and coughing (Baker and Grant 2018e).

4.2 Dose-Response Assessment

4.2.1 Human Health Dose-Response

No toxicity data were available for human health effects. USEPA waived the human health effects 

data requirements for acute, subchronic, chronic, and developmental toxicity, mutagenicity, and 

immunotoxicity for registered dried blood pesticides due to its nontoxic properties and the 

manufacturing process, which ensures the denaturation of proteinaceous material and 

inactivation of potential mammalian pathogens (i.e., endogenous or exogenous contaminants) in 

dried blood used as a repellent (USEPA 1991).
12

4.2.2 Ecological Effects Dose Response

Aquatic Effects Analysis

No data were available. USEPA waived the ecotoxicity data requirements for fish, aquatic 

invertebrates, and aquatic plants for dried blood during registration review (USEPA 1991). 

Terrestrial Effects Analysis

No data were available. USEPA waived the ecotoxicity data requirements for avian, mammal, 

terrestrial invertebrate, and terrestrial plant toxicity for dried blood during registration review 

(USEPA 1991).

Dried blood is not considered phytotoxic (USEPA 1991).

4.3 Exposure Assessment and Risk Characterization

4.3.1 Human Health Exposure and Risk Characterization

Dried blood used to produce MRP-repellent products comes from bovine and porcine 

slaughterhouses (USEPA 1991). The manufacturing process of dried blood products ensures the 

denaturation of proteinaceous material and the inactivation of potential pathogens (USEPA 1991).

Dried blood MRP repellent products cannot be used on food or feed crops, and dried blood is 

readily biodegradable in the environment. Therefore, dietary exposures through food and drinking 

water are negligible (Baker and Grant 2018e).

WS distributes dried blood MRP products to cooperators, which has a negligible risk to applicators 

or the general public based on their environmental fate properties and low toxicity profile (Table 

1). Any potential future use by WS of repellent products containing dried blood would also have 

negligible risk to the general public or WS applicators.

4.3.2 Ecological Exposure and Risk Characterization

The low-use volumes, use sites, biodegradability, and lack of phytotoxicity or persistence in the 

environment indicate MRP repellents containing dried blood pose little to no exposure risk to 

terrestrial species. Furthermore, dried blood is a naturally occurring substance (USEPA 1991). 

Target pest animals visiting the use sites allowed for these products will be repelled and will avoid 

further exposure.

The USEPA determined that there will be no effects on nontarget species from the use of 

registered repellent products containing dried blood when used as directed (USEPA 1991).

5 GARLIC AND GARLIC OIL

5.1 Problem Formulation

5.1.1 Chemical Description and Product Use

Garlic (CAS number N/A) is usually from the bulb of the garlic plant (Allium sativum) and is a 

commonly consumed food. When used in pesticides, dehydrated garlic is ground into a powder 

or flaked (Baker and Grant 2018f). Garlic oil (CAS number 8000-78-0) is a naturally occurring oil 
13

extract from the bulb and other parts of the garlic plant and is an edible oil. Garlic and its primary 

active constituent, garlic oil, are volatile and strongly scented. It works to deter and prevent the 

feeding of some species of mammals, including squirrels, rabbits, and deer (USEPA 2022b). The 

MRP end-use products used to repel animals have concentrations of garlic oil ranging from 0.001 

to 0.12% w/w active ingredient. Garlic oil is currently registered as an active ingredient in 18 

federally registered products (USEPA 2022b). The labels for these products interchangeably list 

the active ingredient as garlic oil, garlic juice, garlic water, or garlic and are water-based 

compounds with a garlic extract or powder. USEPA considers all such variations of A. sativum as

garlic oil under the Pesticide Chemical (PC) Code 128827 (USEPA 2010a). 

WS may use or distribute MRP repellent products containing garlic or garlic oil to cooperators to 

deter herbivores from browsing. These MRPs containing garlic and garlic oil include other MRP 

active ingredients in their formulation, which are covered separately in this assessment. Federally 

registered products containing garlic oil are covered in another Risk Assessment (Chapter 24 Use 

of Registered Chemical Repellents in WDM).

5.1.2 Physical and Chemical Properties

Garlic is a white to yellowish-white solid powder or flake (Baker and Grant 2018f). Garlic oil is a 

light tan to dark green liquid or powder (USEPA 2009c;2022b). Garlic oil has a pungent odor and 

is partially to fully soluble in water (USEPA 2009c;2022b). Garlic oil has a boiling point of 136.32°C 

and a vapor pressure of 10 mm Hg at 20°C (Baker and Grant 2018f).

5.1.3 Environmental Fate

Garlic and garlic oil biodegrade rapidly and have low to no persistence in the environment (USEPA 

2022b).

5.1.4 Hazard Identification

Garlic and garlic oil are classified as GRAS when used as food additives (21 CFR 182.10, 182.20, 

and 182.1317). Garlic oil is also exempt from the requirement of a tolerance in or on all food 

commodities when used as a pesticide active ingredient or inert ingredient under 40 CFR 

180.950(a) and (c) because they are a commonly consumed food and edible oil (USEPA 

2010a;2022b).

USEPA (2022b) reviewed the Incident Data System and identified 15 reported incidents 

associated with garlic oil, eight incidents pertaining to human health, six involving domestic 

animals, and one involving both human health and a domestic animal. None of the incidents were 

serious, and all the products contained other active ingredients, such as capsaicin and egg solids.

USEPA waived data requirements for quantitative dietary (food and drinking water) exposure due 

to garlic oils' composition and physical and chemical properties, broad availability for human 

consumption, and its benefits to human health (USEPA 2022b).
14

5.2 Dose-Response Assessment

5.2.1 Human Health Dose-Response

Garlic and garlic oil have minimal human health hazards, are commonly consumed food 

commodities, and have a significant history of human exposure, demonstrating minimal toxicity 

(USEPA 2022b). 

5.2.2 Ecological Effects Dose Response

No ecotoxicity data for garlic or garlic oil are available for mammals or birds. Garlic oil is practically 

nontoxic to cabbage looper (Trichoplusia ni) larvae with an acute contact LD50 of 22.7 μg/insect 

(Machial et al. 2010). USEPA (2022b) concluded garlic oil would not result in a hazard or toxic 

risk to nontarget organisms and waived all nontarget organism and environmental fate data 

requirements for garlic oil due to garlic oils' natural occurrence, nontoxic mode of action as a 

repellent, and biodegradability.

USEPA (2022b) reviewed the Incident Data System and identified four reported incidents 

associated with garlic oil. These incidents included minor exposure and damage to plants, 

although it is unclear if the damage resulted from garlic oil as the products also contained 

capsaicin and egg solids.

5.3 Exposure Assessment and Risk Characterization

5.3.1 Human Health Exposure and Risk Characterization

USEPA (2022b) concluded that applications of registered products containing garlic oil according 

to label instructions would not result in harm to the general population or applicators, which is 

likely to be true for MRP products as well. USEPA has not yet assessed garlic oil under their 

Endocrine Disruptor Screening Program (USEPA 2022b).

Due to the low toxicity of garlic or garlic oil to humans or mammals, the low volumes of MRP 

products containing garlic or garlic oil that WS uses, and the training of WS applicators in the 

proper use of PPE and pesticides, the risks to WS applicators or the public from WS use or 

distribution of MRP repellent products containing garlic and garlic oil are negligible.

5.3.2 Ecological Exposure and Risk Characterization

The lack of toxicity and the environmental fate properties of garlic and garlic oil combined with the 

low concentrations of garlic and garlic oil in MRP products used by WS indicate WS use or 

distribution of MRP products containing garlic and garlic oil will not harm nontarget terrestrial or 

aquatic species.

6 POTASSIUM SORBATE

6.1 Problem Formulation

6.1.1 Chemical Description and Product Use

Potassium sorbate (chemical formula C6H7KO2; CAS number 24634-61-5; synonyms: sorbic acid, 

potassium salt, potassium salt of sorbic acid, and potassium (2E,4E)-hexa-2,4-dienoate); is a 
15

naturally occurring compound in foods (fruits and berries) (ACS 2023, Baker and Grant 2018d). 

Potassium sorbate is synthetically produced by mixing sorbic acid (CAS number 10-44-1) with 

potassium hydroxide (USEPA 2003). Potassium sorbate's primary uses as an MRP active 

ingredient include fungicide, bactericide, algicide, or insect repellent (Baker and Grant 2018d). In 

addition to being an MRP active ingredient, potassium sorbate is also an MRP inert ingredient (40 

CFR 152.25(f)(2)) and a commodity inert ingredient in registered pesticides (USEPA 2023b). All 

registered pesticide products containing potassium sorbate as an active ingredient were 

voluntarily canceled in the 1980s for unknown reasons (under CAS number 590-00-1)(USEPA 

2023a).

Potassium sorbate is also an active ingredient in an MRP repellent product used or distributed by 

WS to repel target deer and other mammal species (Table 1). The MRP product that WS uses 

containing potassium sorbate includes other MRP active ingredients in its formulation, which are 

covered separately in this assessment. WS may use and distribute products containing potassium 

sorbate to cooperators to deter herbivores from browsing.

6.1.2 Physical and Chemical Properties

Potassium sorbate is a white, crystalline solid highly soluble in water (Baker and Grant 2018d, 

USEPA 2003). Potassium sorbate has a density of 1.363 g/cm3 at 25°C, a melting point of 270

°C, and a boiling point of 446°C (Baker and Grant 2018d, USEPA 2003). Potassium sorbate 

has a vapor pressure of <0.01 mm Hg at 20°C and a log Kow of -1.72 at a pH of 6.5 and 1.32 at 

a pH of 2.5 (Baker and Grant 2018d, ECHA 2013, USEPA 2003).

6.1.3 Environmental Fate

Potassium sorbate disassociates in solution to ionic potassium and its free acid, sorbic acid

(Baker and Grant 2018d). Potassium sorbate has a half-life in soil of 416 hours, a half-life in the 

air of 2.6 hours, and a half-life in water of 208 hours (Baker and Grant 2018d), indicating low to 

no persistence in the environment. Potassium sorbate, its free acid, and sorbic acid are readily 

biodegradable in the environment and do not bioaccumulate in aquatic organisms (ECHA 2013, 

USEPA 2003). 

6.1.4 Hazard Identification

Potassium sorbate is classified as GRAS when used as a food additive (21 CFR 182.3640) and 

is a commonly used food preservative (USEPA 2003). Potassium sorbate is also exempt from the 

requirement of a tolerance in or on all food commodities when used as an MRP or registered 

pesticide inert ingredient under 40 CFR 180.950 and 40 CFR 180.1233 (USEPA 2003).

The National Pesticide Information Center (NPIC) received two reports of human health-related 

incidents involving potassium sorbate between 1996 and 2016, but both involved other active 

ingredients in addition to potassium sorbate, and symptoms were not reported (Baker and Grant 

2018d). When ingested, a small, undefined subgroup of people may suffer from contact 

dermatitis, hives, stinging sensations from dermal exposure, and 'burning mouth syndrome'

(Baker and Grant 2018d, ECHA 2013). An incident of repeated occupational exposure in a dairy 
16

plant that led to severe rashes in an exposed worker was also reported (Baker and Grant 2018d, 

Le Coz and Abensour 2005).

6.2 Dose-Response Assessment

6.2.1 Human Health Dose-Response

Acute Toxicity

The reported acute oral LD50 values for potassium sorbate range from 4,340 to 6,170 mg/kg-bw 

in rats and 3,800 mg/kg-bw in mice (Toxicity Category III–IV) (Baker and Grant 2018d, USEPA 

2003). The only acute inhalation toxicity data for potassium sorbate was for a 50% aqueous 

solution; based on this study, the acute inhalation of 4-hr LC50 for potassium sorbate in rats was 

>5.15 mg/L (Category IV) (ECHA 2013). Potassium sorbate can cause eye irritation and contact 

dermatitis but is not a skin sensitizer (ECHA 2013, USEPA 2003).

Subchronic, Chronic, Developmental, and Reproductive Toxicity, Neurotoxicity Effects, 

Carcinogenicity and Mutagenicity, Immunotoxicity Effects, Endocrine Effects

In 90-day oral toxicity studies on potassium sorbate's free acid and sorbic acid in mice, rats, and 

dogs, there were no adverse effects observed for mice or dogs at the levels tested, and the 

NOAEL was 2,500 mg/kg-bw/day in rats (Baker and Grant 2018d, USEPA 2003). Potassium 

sorbate is expected to be less toxic than sorbic acid (USEPA 2003).

In a developmental toxicity study (oral gavage) with potassium sorbate in rats, the NOAELs for 

maternal toxicity, embryotoxicity, and teratogenicity were 340 mg/kg-bw/day, which was the 

highest dose level tested (ECHA 2013). Potassium sorbate is not considered toxic to reproduction

(ECHA 2013).

Potassium sorbate is not considered to be genotoxic or carcinogenic, based on a lack of 

mutagenicity in an Ames assay, a lack of chromosomal aberrations in Chinese hamster 

(Cricetulus griseus) fibroblast cells, and a negative result for a carcinogenicity study in mice. 

However, results from sister chromatid studies with Chinese hamster lung cells were inconclusive

(Baker and Grant 2018d, USEPA 2003). Potassium sorbate is not considered to be a carcinogen 

by the International Agency for Research on Cancer (Baker and Grant 2018d).

No subchronic, neurotoxicity, or immunotoxicity data was available for the human health effects 

of potassium sorbate.

6.2.2 Ecological Effects Dose Response

Aquatic Effects Analysis

Potassium sorbate is nontoxic to freshwater fish and aquatic invertebrates (ECHA 2013). The 48-

hr EC50 (immobilization) is 982 mg/L in the water flea (Daphnia magna) (ECHA 2013). The 96-hr 

LC50 is >1,000 mg/L in rainbow trout (ECHA 2013). No other ecotoxicity data were available for 

aquatic animals or plants.
17

Terrestrial Effects Analysis

Potassium sorbate is practically nontoxic to mammals based on the acute oral toxicity values in 

rats (>3,340 mg/kg-bw) and mice (>3,800 mg/kg-bw) (Baker and Grant 2018d, USEPA 2003). No

other ecotoxicity data are available for terrestrial animal or plant species.

6.3 Exposure Assessment and Risk Characterization

6.3.1 Human Health Exposure and Risk Characterization

Potassium sorbate has minimal toxicity or other human health hazards and is commonly found in 

foods and other products (USEPA 2003). Due to the low toxicity of potassium sorbate to humans 

or mammals, the low volumes used by WS, and the training of WS applicators in the proper use 

of PPE and pesticides, the risks to WS applicators or the public from WS use or distribution of the 

MRP repellent product containing potassium sorbate are negligible.

6.3.2 Ecological Exposure and Risk Characterization

The potassium sorbate within the MRP product used and distributed by WS is not likely to result 

in a hazard or toxic risk to nontarget aquatic or terrestrial organisms, based on the lack of toxicity 

and the environmental fate properties for potassium sorbate and WS use patterns for the MRP 

product containing potassium sorbate. 

7 PUTRESCENT WHOLE EGG SOLIDS

7.1 Problem Formulation

7.1.1 Chemical Description and Product Use

Putrescent whole egg solids (CAS number 51609-52-0; synonym: egg solids) are simply dried 

chicken eggs that have been pasteurized and are free of viable pathogens (USEPA 2018). Egg 

solids repel mammals, primarily from feeding on vegetation, by an aversive odor and taste 

(USEPA 2018). The FDA considers putrescent whole egg solids as a GRAS chemical when used 

as a food additive. Putrescent whole egg solids are found in MRPs and several federally 

registered pesticides (under the active ingredient name egg solids), which USEPA classifies as 

biopesticides or biochemical pesticide active ingredients (USEPA 2018). Federally registered 

chemical repellent products containing egg solids are covered in another risk assessment

(Chapter 24 Use of Registered Chemical Repellents in WDM). Egg solids are also an inert 

commodity ingredient in registered pesticides (USEPA 2023b).

MRPs and federally registered products containing putrescent whole egg solids are used in home 

gardens, nurseries, greenhouses, and forestry plantations, on various fruit and nut trees, and on 

ornamental woody shrubs (USEPA 2018). Applications are typically applied in dust and liquid 

forms (USEPA 2018). MRP products containing putrescent whole egg solids can be used before 

and after flowering. USEPA has established a tolerance exemption for putrescent whole egg 

solids for pesticide food uses in accordance with the criteria specified in 40 CFR 180.1071. 

However, federally registered product labels for repellent products do not allow for use on plants 

intended for human consumption or in fields where drift could occur into fields with plants intended 
18

for human consumption because the proteins in putrescent whole egg solids may cause allergic 

reactions in some people (USEPA 2018;2022c).

The MRP repellent products that WS uses or distributes that contain putrescent whole egg solids 

include other MRP active ingredients in their formulation (Table 1), which are covered separately 

in this assessment. 

7.1.2 Physical and Chemical Properties

Putrescent whole egg solids are a light brown to beige powder with a malty odor (USEPA 2011d). 

They are practically insoluble in water (USEPA 2011c).

7.1.3 Environmental Fate

Putrescent whole egg solids are organic matter that rapidly degrades (decomposes) in the 

environment and is expected to be non-persistent (USEPA 1992).

7.1.4 Hazard Identification

Putrescent whole egg solids are nontoxic to humans. In registered pesticides, egg solids are 

classified as a biopesticide by USEPA and are considered GRAS by FDA when used as a food 

additive (USEPA 1992;2018). USEPA waived most of the data requirements for the reregistration 

of pesticide products containing egg solids, including data for toxicology, residue chemistry, 

human exposure, and ecological effects and environmental fate (USEPA 2011a).

The odor and taste of putrescent whole egg solids act as a repellent when applied to plants that 

repel white-tailed deer and other target animals from foraging (USEPA 2018). The target 

mammals are sensitive to the smell and taste of putrescent whole egg solids; however, the odor 

is barely detectable to humans (USEPA 2018).

Between 1996 and 2016, 32 human health-related incidents in NPIC involved accidental ingestion

and resulted in nausea, inhalation exposures, and eye exposures resulting in eye irritation (Baker 

and Grant 2018b). USEPA (2018) reviewed the Incident Data System and found one incident 

report of a person that experienced discomfort after inhaling a product containing egg solids, 

which was deemed a misuse of the product.

7.2 Dose-Response Assessment

7.2.1 Human Health Dose Response

Acute Toxicity

Putrescent whole egg solids are practically nontoxic on an acute oral, dermal, and inhalation basis

(USEPA 2011d). The LD50 values for acute oral and dermal toxicity are >5,000 mg/kg-bw (Toxicity 

Category IV) (USEPA 2011a). The acute inhalation LC50 is >2.10 mg/L (Toxicity Category III)

(USEPA 2011a). In acute eye irritation studies, putrescent whole egg solids caused corneal 

irritation, which cleared within 48 hours (Toxicity Category III) (USEPA 2011d). Putrescent whole 

egg solids are a slight dermal irritant (Toxicity Category IV) and may be a skin sensitizer (USEPA 

2011d).
19

Subchronic and Chronic Toxicity

Data is not available on the subchronic and chronic toxicity of putrescent whole egg solids. 

USEPA waived these studies for registered products due to the lack of acute toxicity.

Developmental and Reproductive Toxicity, Neurotoxicity Effects, Carcinogenicity and 

Mutagenicity, Immunotoxicity Effects, Endocrine Effects

USEPA waived these studies for registered products due to the lack of acute toxicity. No reports 

of adverse effects were submitted to the USEPA, and it is not expected to have adverse effects 

on humans (USEPA 1992;2011a).

7.2.2 Ecological Effects Dose-Response

Aquatic Effects Analysis

USEPA waived the ecotoxicity data requirements for aquatic species for putrescent whole egg 

solids because of their low hazard and risk to the environment (USEPA 2011b). 

Terrestrial Effects Analysis

USEPA waived the ecotoxicity data requirements for terrestrial species because of the low hazard 

and risk to the environment from putrescent whole egg solids (USEPA 2011b). USEPA (2011b)

concluded putrescent whole egg solids would not result in a hazard or toxic risk to nontarget 

organisms. 

USEPA (2018) reviewed the Incident Data System for reported incidents and determined it 

unlikely that egg solids used according to their labels would cause adverse effects on the 

environment. Four incidents for egg solids involved dogs ingesting small amounts of the product, 

with some experiencing diarrhea and vomiting. Four incidents reported plant damage. From the 

incidents reported to NPIC between April 1, 1996, and March 30, 2016, accidental ingestion was 

the main exposure route, with some of the exposed animals vomiting; however, many reported 

no symptoms (Baker and Grant 2018b).

7.3 Exposure Assessment and Risk Characterization

7.3.1 Human Health Exposure and Risk Characterization

The product labels for registered repellents containing egg solids do not allow applications or drift 

onto plant parts meant for human consumption. This limits exposure through dietary consumption; 

putrescent whole egg solids may cause an allergic reaction in some people. USEPA (2011a;2018)

concluded that applications of registered products containing egg solids as the active ingredient 

according to label instructions would not result in harm to the general population or applicators. 

Similarly, USEPA concluded that registered products containing egg solids that also contain 

capsaicin, garlic oil, or both will not result in harm to people (USEPA 2009b).

The labels for registered products containing egg solids do not require PPE. Due to the low toxicity 

of putrescent whole egg solids to humans and other mammals, the low volumes used or 

distributed by WS, and the training of WS applicators in the proper use of pesticides, the risks to 
20

WS applicators or the public from WS use and distribution of MRP repellent products containing

putrescent whole egg solids are negligible.

7.3.2 Ecological Exposure and Risk Characterization

Putrescent whole egg solids break down rapidly in the environment, indicating runoff and leaching 

into water resources would be minimal. WS expects aquatic exposure to putrescent whole egg 

solids from WS use, and the distribution of MRP products containing putrescent whole egg solids

will be negligible.

USEPA (2011b) concluded egg solids would not result in a hazard or toxic risk to nontarget 

organisms. The lack of toxicity and the environmental fate properties for putrescent whole egg 

solids and WS low use patterns indicate WS use of MRP products containing putrescent whole 

egg solids will not harm nontarget terrestrial and aquatic species.

8 SODIUM LAURYL SULFATE (SLS)

8.1 Problem Formulation

8.1.1 Chemical Description and Product Use

Sodium lauryl sulfate or SLS (chemical formula C12H25NaO4S; CAS number 151-21-3; synonyms:

sodium dodecyl sulfate, sulfuric acid monododecyl ester, and sodium salt) is an anionic surfactant

derived from coconut or palm kernel oil that is commonly found in soaps and other products for 

its detergent properties (Baker and Grant 2018c, NIH 2023a, USEPA 2009d). In addition to being 

an MRP, SLS is also an inert ingredient in over 370 registered pesticides (USEPA 2009d) and an

active ingredient in two USEPA registered, multi-active ingredient pesticides: an antiviral facial 

tissue and a hospital bacterial disinfectant (USEPA 2023c).

An MRP product that WS uses and distributes to cooperators, Liquid Fence, deters mammalian 

herbivores from browsing. The product includes SLS and other MRP active ingredients in its 

formulation (Table 1), which are covered separately in this assessment. SLS is also the sole active 

ingredient within MRP products used by WS as wetting agents to control flocking blackbirds 

(Table 1) (USDA 2021). SLS used as a wetting agent must remain heated above 21°C (70°F)

before and during use to ensure proper flow throughout the spray application (USDA 2021).

8.1.2 Physical and Chemical Properties

SLS in liquid form is white to pale yellow and has a faint odor of fatty substances (NIH 2023a).

SLS has a reported melting point ranging from 204–405°C, a boiling point of 588°C, and is 

moderately soluble in water (Baker and Grant 2018c, NIH 2023a). SLS has a density of 0.6 g/cm3

at 25°C (Baker and Grant 2018c), reported vapor pressures ranging from 4.7x10-13 to 1.1x10-12

mm Hg at 25°C, and a log Kow of 1.6 (Baker and Grant 2018c, NIH 2023a).

8.1.3 Environmental Fate

SLS has a half-life in soil of 77.5 hours, a half-life in the air of 0.7 hours, and a half-life in water of 

19.8 hours (Baker and Grant 2018c), indicating low to no persistence in the environment. SLS is 

rapidly biodegradable (Baker and Grant 2018c, NIH 2023a, OECD 1995, USEPA 2009e;2019).
21

8.1.4 Hazard Identification

SLS is considered to be low to moderately toxic to humans with a probable oral lethal dose 

between 500–5,000 mg/kg-bw (Baker and Grant 2018c, USEPA 2009d;2019). SLS can cause 

contact dermatitis in humans and erythemato-papular allergic reactions in approximately 6.4% of 

people incidentally exposed (Baker and Grant 2018c).

SLS is classified as GRAS when used as a food additive with limitations (21 CFR 172.822) and

is exempt from the requirement of a tolerance for residues in foods (40 CFR 180.940).

Between 1996 and 2016, there were 11 human health-related incidents involving SLS in the 

National Pesticide Information Center (NPIC), but all involved active ingredients in addition to SLS 

(Baker and Grant 2018c). USEPA reviewed the Incident Data System between 1948 and 2010

and found only one adverse effects incident report for SLS, where a person experienced blisters 

on their face and nose, which remained for 3.5 weeks after the exposure to SLS (Baker and Grant 

2018c, USEPA 2010b). In that same period, USEPA (2010b) reported 76 incidents associated 

with lauryl sulfates involving domestic animals, including hair loss, difficulty breathing, and rashes.

USEPA waived the data requirements for quantitative dietary (food and drinking water) exposure 

due to SLS's toxicity, broad availability for human consumption, and history of safe use (USEPA 

2022b).

8.2 Dose-Response Assessment

8.2.1 Human Health Dose-Response

Acute Toxicity

SLS has an acute oral LD50 of 1,288 mg/kg-bw (Toxicity Category III) (Baker and Grant 2018c, 

Merck 2023, NIH 2023a, USEPA 2009d), an acute inhalation (1-hr) LC50 of >3,900 mg/L in rats

(Toxicity Category IV), and an acute dermal LD50 of 600 mg/kg-bw in rabbits (Toxicity Category 

II) (Baker and Grant 2018c, NIH 2023a). SLS is a moderate eye and skin irritant but not a skin 

sensitizer (Baker and Grant 2018c, NIH 2023a).

Subchronic and Chronic Toxicity

In a 28-day subchronic oral (gavage) toxicity study in rats that were administered SLS in doses 

of 0, 30, 100, and 300 (which was increased to 600 after 14 days) mg/kg-bw/day, the NOAEL for 

SLS was 100 mg/kg-bw/day, and the LOAEL was 300/600 mg/kg-bw/day (NIH 2023a, USEPA 

2009d). Observed adverse effects in the 300/600 mg/kg-bw/day group included decreased weight 

gain (males), increased kidney, brain, and liver weights, increased levels of alanine

aminotransferase, decreased thymus weights, ulcerations and bleeding in the stomach, and 

reversible alterations of the tongue, myocardium, and forestomach (NIH 2023a). In a 28-day 

subchronic oral (dietary) toxicity study, rats were administered SLS in doses of 0, 25, 50, 110, 

200, 420, 830, and 1,600 mg/kg-bw/day (USEPA 2009d). The NOAEL for SLS was 108 mg/kgbw/day, and the LOAEL was 207 mg/kg-bw/day based on increased liver weights, hypertrophy, 

and elevated alanine aminotransferase levels (USEPA 2009d).
22

In a 90-day oral (dietary) toxicity study with SLS in rats at 0, 58, 116, 230, 460, 920, and 1,840 

mg/kg-bw/day, the NOAEL was 460 mg/kg-bw/day (USEPA 2009d). The LOAEL was 920 mg/kgbw/day based on increased liver weights, elevated liver enzymes, and histopathological changes 

(USEPA 2009d). In a one-year dietary toxicity study in beagles (2 males and 2 females per group), 

the NOAEL for SLS was 400 mg/kg-bw/day, and the LOAEL was 800 mg/kg-bw/day; the only 

observed adverse effect was decreased rate in body weight gain (NIH 2023a).

No subchronic or chronic toxicity studies were available for dermal or inhalation exposure routes

(USEPA 2009d).

Developmental and Reproductive Toxicity, Neurotoxicity Effects, Carcinogenicity and 

Mutagenicity, Immunotoxicity Effects, Endocrine Effects

In a developmental oral (gavage) toxicity study with SLS in mice and rabbits, the developmental 

NOAEL for SLS was 300 mg/kg-bw/day, and the LOAEL was 600 mg/kg-bw/day, with total litter 

losses secondary to maternal effects and minor skeletal anomalies in mice (Baker and Grant 

2018c, USEPA 2009d). The NOAEL for rats was 600 mg/kg-bw/day, the highest dose level tested 

(USEPA 2009d). The maternal LOEL was 300 mg/kg-bw/day for rats, rabbits, and mice, with 

reduced weight gain, and the maternal NOEL was 2 mg/kg-bw/day (USEPA 2009d).

In a reproductive toxicity study in mice, the NOAEL for reproduction was 1,000 mg/kg-bw/day,

and the LOAEL could not be established (summarized by OECD (1995). The author concluded 

SLS did not cause adverse effects on fertility as the highest dose tested was above doses that 

cause significant parental toxicity.

SLS was not genotoxic in a bacterial reverse mutation test or an in-vivo mammalian micronucleus 

assay (USEPA 2009d). No carcinogenicity studies were available for SLS, but the negative results 

of a carcinogenicity study for a related substance suggest SLS is also not carcinogenic (USEPA 

2009d).

No reproductive toxicity, neurotoxicity studies, or immunotoxicity studies were available (USEPA 

2009d).

8.2.2 Ecological Effects Dose Response

Aquatic Effects Analysis

SLS is moderately toxic to fish and moderately to highly toxic to aquatic invertebrates (Table 5).

An estimated bioconcentration factor (BCF) of 71 suggests a moderate potential for 

bioconcentration in aquatic organisms (NIH 2023a).

USEPA (2009e) reported a 48-hr EC50 for marine aquatic plants (algae, Champia parvula) as 0.3 

mg/L.

Terrestrial Effects Analysis

There is relatively little ecotoxicity data available for terrestrial animals or plants. SLS has low 

toxicity to terrestrial mammals based on the acute oral LD50 of 1,288 mg/kg-bw in rats (USEPA 
23

2009d). USEPA (2009e) did not require avian ecotoxicity data or additional mammalian 

ecotoxicity data during registration review of the registered SLS products. 

There are no ecotoxicity data available for terrestrial invertebrates. However, Baker and Grant 

(2018c) reported studies on the efficacy of SLS through mechanical means (lowering the surface 

tension of the water) or synergistic effects with other active ingredients when MRP products are 

used as insecticides against various invertebrate pest species. 

SLS may have some phytotoxicity to terrestrial plants (Baker and Grant 2018c). OECD (1995)

reported a 48-hr EC50 of 361 mg/L for the chickpea (Cicer arietinum) and 384 mg/L for the white 

lupin (Lupinus albus).

8.3 Exposure Assessment and Risk Characterization

8.3.1 Human Health Exposure and Risk Characterization

Occupational exposure to SLS may occur through inhalation and dermal routes of exposure. The 

general public is consistently exposed to SLS via ingestion and dermal contact with numerous 

categories of food and cosmetic consumer products containing SLS (NIH 2023a). Due to the low 

toxicity of SLS to humans or mammals, the low volumes used by WS, and the training of WS 

applicators in properly using PPE and pesticides, the risks to WS applicators or the public from 

WS's use of SLS are negligible.

8.3.2 Ecological Exposure and Risk Characterization

SLS is readily biodegradable and is found at very low concentrations in the deer and rabbit MRP 

repellent product (0.040% w/w) used by WS, which WS also uses at low volumes. Based on their 

low toxicity, MRP products containing SLS poses little to no risk to nontarget terrestrial 

mammalian species. Because WS applicators apply SLS wetting agents directly to the target bird 

species, risks of applying SLS to nontarget bird species are minimal.

Aquatic fish and invertebrate species are sensitive to or at risk from SLS. However, WS's use of 

MRP products containing SLS at blackbird roost sites away from where runoff is likely to enter 

water resources (USDA 2021) reduces risks to nontarget aquatic species. Any low risks to 

nontarget terrestrial plant species will be localized to where the birds are roosting
24

Table 5. Acute and chronic toxicity to aquatic vertebrates and invertebrates for SLS.

Taxonomic group Test species Test Result Reference

Freshwater Fish Rainbow Trout (Oncorhynchus mykiss) 24-hr LC50 58.1 mg/L (Baker and Grant 2018c)

Freshwater Fish Rainbow Trout (Oncorhynchus mykiss) 48-hr LC50 41.2 mg/L (Baker and Grant 2018c)

Freshwater Fish Rainbow Trout (Oncorhynchus mykiss) 96-hr LC50 24.9 mg/L (Baker and Grant 2018c)

Freshwater Fish Sheepshead Minnow (Cyprinodon variegatus) 96-hr LC50 1.7 mg/L (NIH 2023a)

Freshwater Fish Striped Dwarf Catfish (Macrones vittatus) 96-hr LC50 1.39 mg/L (OECD 1995)

Marine Fish Inland Silverside (Menidia beryllina) 7-day LC50 (larvae) 1.8 mg/L (USEPA 2009e)

Freshwater Invertebrates Rotifer (Brachionus rubens) 48-hr EC50 1.8 mg/L (USEPA 2009e)

Freshwater Invertebrates Rotifer (Brachionus rubens) 24-hr EC50 1.35 mg/L (OECD 1995)

Freshwater Invertebrates Water Flea (Daphnia magna) 48-hr EC50 1.8 mg/L (OECD 1995)

Freshwater Invertebrates Water Flea (Daphnia magna) 40-day NOEC 2 mg/L (USEPA 2009e)

Marine and Estuarine 

Invertebrates Mysid (Americamysis bahia) 96-hr LC50 4.2 mg/L (NIH 2023a)

Marine and Estuarine 

Invertebrates Mysid (Metamysidopsis swifti) 96-hr LC50 3.2 mg/L (NIH 2023a)

Marine and Estuarine 

Invertebrates Eastern Oyster (Crassostrea virginica) 48-hr EC50 1.7 mg/L (NIH 2023a)

Marine and Estuarine 

Invertebrates Pacific Oyster (Crassostrea gigas) 48-hr EC50 0.84 mg/L (OECD 1995)

Marine and Estuarine 

Invertebrates American Lobster (Homarus americanus) 96-hr EC50 0.72 mg/L (OECD 1995)
25

9 THYME OIL

9.1 Problem Formulation

9.1.1 Chemical Description and Product Use

Thyme oil (CAS number 8007-46-3; synonym oil of thyme) is a naturally occurring oil extract from 

the flowering tops of thyme plants (Thymus vulgaris and T. zygis). Thyme oil is used in cosmetics, 

aromatherapy treatments, topical treatments, and toothpaste (Baker and Grant 2018g). Thyme 

oil consists of 3–80% thymol, a volatile phenol (CAS number 89-83-8) (Baker and Grant 2018g, 

NIH 2023b). Thymol is thought to be the main active component in thyme oil (Baker and Grant 

2018g). Thyme oil has demonstrated insecticidal properties as well as anti-microbial and antifungal properties (Baker and Grant 2018g). Thyme oil is also a non-food-use-only inert ingredient 

in registered pesticides (USEPA 2023b)

The MRP product containing thyme oil that WS uses or distributes has other MRP active 

ingredients in its formulation, which are covered separately in this assessment. WS may use and 

distribute MRP products containing thyme oil to cooperators to deter herbivores from browsing.

In addition to being an MRP, thyme oil (under the active ingredient name oil of thyme) is the sole 

active ingredient in several botanical (flower oil) products registered with USEPA that target fungal 

and bacterial pathogens on crops and ornamental plants and is an active ingredient in one 

registered, multi-active ingredient botanical insecticide (USEPA 2023e).

9.1.2 Physical and Chemical Properties

Thyme oil is a colorless to reddish-brown liquid (Baker and Grant 2018g). Thyme oil has the odor

of thyme and is very slightly soluble in water (Baker and Grant 2018g, Merck 2023). Thyme oil 

has a melting point of 250°C and a boiling point of 190°C (Baker and Grant 2018g). Thyme oil 

has a density of 0.916 g/cm3

, a vapor pressure of 0.167 mm Hg at 25°C, and a log Kow ranging 

from -1.77 to -1.69 (Baker and Grant 2018g).

9.1.3 Environmental Fate

Thyme oil has a half-life in soil of 720 hours, a half-life in air of 2.4 hours, and a half-life in water 

of 360 hours (Baker and Grant 2018g), indicating low to moderate persistence in the environment. 

Thyme oil rapidly biodegrades in the environment (USEPA 2020).

9.1.4 Hazard Identification

Thyme oil from T. vulgaris and the T. zygis var. gracilis is considered GRAS when used as a food 

additive (21 CFR 182.20). 

USEPA (2020) reviewed the Incident Data System and identified 2 reported human incidents 

associated with thyme oil with moderate adverse effects, including an allergic reaction. The 

remaining three incidents report adverse effects on domestic animals ranging from minor to one 

fatality. No information was reported for the domestic animal fatality.

9.2 Dose-Response Assessment

9.2.1 Human Health Dose-Response
26

Acute and Subchronic Toxicity

The acute oral LD50 values for thyme oil are 2,840 mg/kg-bw in rats (Toxicity Category III), 1,250 

mg/kg-bw in mice (Toxicity Category III), and >5,000 mg/kg-bw in rabbits (Toxicity Category IV)

(Baker and Grant 2018g, USEPA 2020). In rabbits, the acute dermal LD50 for thymol is >5,000 

mg/kg-bw, indicating that thyme oil is also nontoxic for dermal exposure (Baker and Grant 2018g). 

Oil of thyme is considered a sensitizer (USEPA 2020).

In a subchronic (28-day) oral (gavage) toxicity study in rats, the NOAEL was determined to be 

100 mg/kg-bw/day (Rojas-Armas et al. 2019). 

Chronic, Developmental, and Reproductive Toxicity, Neurotoxicity Effects, Carcinogenicity and 

Mutagenicity, Immunotoxicity Effects, Endocrine Effects

Thyme oil is not considered to be genotoxic, based on a lack of mutagenicity in an Ames assay 

and a negative result for genotoxicity in a chromosomal aberration assay in Chinese hamster 

fibroblasts (Cohen et al. 2021). 

No neurotoxicity, immunotoxicity, chronic, developmental, or reproductive toxicity data were 

available for human health effects of thyme oil. These data were again waived by USEPA during 

the registration review (USEPA 2020).

9.2.2 Ecological Effects Dose Response

Aquatic Effects Analysis

Thyme oil is slightly toxic to aquatic invertebrates with a 48-hr EC50 (immobilized) of 11.787 mg/L

in the water flea (Daphnia magna) (Arslan et al. 2014). This toxicity is likely due to the thymol

component within thyme oil, which is moderately toxic to aquatic invertebrates (48-hr LC50 for 

thymol is 4.9 mg/L for Daphnia magna) (Baker and Grant 2018g).

Thyme oil is nontoxic to freshwater fish with a 24-hr, 48-hr, and 72-hr LD50 of 21,100 mg/L and a 

96-hr LD50 of 20,500 mg/L for juvenile coho salmon (Oncorhynchus kisutch) and a 24-hr, 48-hr, 

72-hr, and 96-hr LD50 of 16,100 mg/L for rainbow trout (O. mykiss) (Stroh et al. 1998).

USEPA waived all nontarget organism and environmental fate data requirements for thyme oil 

during the registration review (USEPA 2020). USEPA (2020) reviewed the Incident Data System, 

and no reported ecological incidents were associated with thyme oil.

Terrestrial Effects Analysis

The acute oral LD50 values for thyme oil are 2,840 mg/kg-bw in rats, 1,250 mg/kg-bw in mice, and 

>5,000 mg/kg-bw in rabbits (Baker and Grant 2018g, USEPA 2020). No other data is available 

on the ecotoxicity of thyme oil to nontarget terrestrial mammals or birds, but toxicity is likely low 

to minimal (USEPA 2020). 

Thyme oil is slightly to moderately toxic to the obliquebanded leafroller (Choristoneura rosaceana) 

larvae on an acute contact basis (LD50 of 11.2 μg/insect) (Machial et al. 2010). Thyme oil appears 
27

to be moderately toxic to honey bees on an acute oral basis, with mortalities occurring at 8 μg/bee 

following 24-hr and 48-hr exposures (Albo et al. 2003). However, acute oral LD50 values could not 

be estimated due to negative curves for mortality with potential delayed consumption and volatility 

of thyme oil, potentially impacting the results at the higher dose levels (Albo et al. 2003). 

9.3 Exposure Assessment and Risk Characterization

9.3.1 Human Health Exposure and Risk Characterization

Thyme oil has minimal toxicity or other human health hazards and is commonly found in consumer 

cosmetics and other products (USEPA 2020). Due to the low toxicity of thyme oil to humans or 

mammals, the low volumes used by WS, and the training of WS applicators in the proper use of 

PPE and pesticides, the risks to WS applicators or the public from WS's use or distribution of the 

MRP repellent product containing thyme oil are negligible.

9.3.2 Ecological Exposure and Risk Characterization

USEPA (2020) concluded thyme oil contained in registered pesticides would not result in a hazard 

or toxic risk to nontarget organisms. The lack of toxicity and the environmental fate properties for 

thyme oil and WS use patterns for the MRP product containing thyme oil will also not pose a risk

to nontarget terrestrial and aquatic species. Although one product containing thyme oil is 

registered with USEPA as a botanical insecticide, USEPA (2020) determined that risk to 

pollinators is not expected due to the use of thyme oils. No risk to terrestrial invertebrates, 

including honey bees, is expected to result from the low concentration of thyme oil (0.010% w/w) 

in the MRP repellent product used and distributed by WS.

10 UNCERTAINTIES AND CUMULATIVE IMPACTS

The uncertainties associated with this risk assessment arise primarily from a lack of information 

about the effects of MRPs, their formulations, metabolites, and potential mixtures on nontarget 

organisms that can occur in the environment. These uncertainties are not unique to this 

assessment but are consistent with uncertainties in human health and ecological risk 

assessments with any environmental stressor. 

Another uncertainty in this risk assessment is the potential for cumulative impacts on human 

health and the environment from the proposed use of MRPs. The potential for cumulative impacts 

is expected to be minimal based on the low volume and minor use of MRPs in the various WS 

uses. Areas where cumulative impacts may occur include 1) repeated worker and environmental 

exposures to chemical repellents from program activities and other sources, 2) exposure to other 

chemicals with a similar mode of action, and 3) exposure to other chemicals affecting the toxicity 

of MRPs. 

From a human health perspective, cumulative impacts on human health are expected to be 

negligible because of these MRPs' favorable toxicity profiles and minimal exposure to workers 

and the public. The lack of exposure and risk to the public suggests that cumulative impacts would 

also be incrementally negligible when factoring in other stressors. 
28

Cumulative impacts on ecological resources are also expected to be incrementally negligible. 

When utilized according to label mandates, risks of the reviewed MRPs to aquatic resources and 

most terrestrial nontarget wildlife are low due to low toxicity and/or mitigated exposure pathways.

There is higher uncertainty on the potential cumulative impacts on aquatic species for any future 

use of sodium lauryl sulfate by WS compared to the other MRPs that WS may use or distribute. 

However, WS applies SLS to blackbird roost sites away from where runoff is likely to enter water 

resources (USDA 2021), which reduces exposure and risks to nontarget aquatic species.

11 SUMMARY

WS uses MRPs to manage several bird and mammal species that damage a variety of agricultural 

and non-agricultural resources. MRPs pose a negligible risk of primary or secondary poisoning to 

nontarget animals, including scavengers. WS use patterns and environmental fate properties 

indicate MRP products used by WS pose no risk to aquatic nontarget wildlife. The WS use pattern 

and application rates of MRPs mostly on private lands, resulting in a negligible risk for the public. 

The dietary risk from MRP exposure to the public is low since most of the repellents are 

considered nontoxic to people, are allowed for food uses, do not threaten drinking water, and 

many are not used by WS on edible plant parts. The risk to WS applicators is also low because 

they receive training in using PPE and pesticides. The release of MRPs into the environment is 

expected to have no or negligible impacts on nontarget species, the public, and the environment, 

including cumulative impacts. 

Although SLS may pose higher risks to aquatic species, aquatic exposure from proposed SLS 

MRP applications is expected to be negligible based on the application method, use-sites away 

from where runoff may expose aquatic species and environmental fate properties of SLS. All MRP

applications are made by hand or with ground-based equipment. The MRPs that WS proposes to 

use or distribute have minimal to no toxicity to nontarget terrestrial species and are all readily 

biodegradable.
29

12 LITERATURE CITED

ACS. 2023. CAS Common Chemistry: Potassium Sorbate. 

https://commonchemistry.cas.org/detail?cas_rn=24634-61-5&search=potassium%20sorbate 

accessed 06/14/2023.

Albo, G.N., C. Henning, J. Ringuelet, F.J. Reynaldi, M.R. De Giusti, and A.M. Alippi. 2003. Evaluation of some 

essential oils for the control and prevention of American Foulbrood disease in honey bees. 

Apidologie 34:417-427.

Andersen, F.A., W.F. Bergfeld, D.V. Belsito, C.D. Klaassen, J.G. Marks, Jr., R.C. Shank, T.J. Slaga, and P.W. 

Snyder. 2011. Finalreport of the safety assessment of cosmetic ingredients derived from Zea mays 

(corn). International Journal of Toxicology 30:17S-39S.

Arslan, O.C., H. Parlak, M. Boyacıoğlu, and M.A. Karaaslan. 2014. Acute toxicity of several essential oils on 

Daphnia magna (Straus, 1816). Ege Journal of Fisheries and Aquatic Sciences 31:137-143.

Baker, B.P., and J.A. Grant. 2018a. Corn Oil Profile Active ingredient eligible for minimum risk pesticide 

use. New York State Integrated Pest Management Program Cornell Cooperative Extension.

_____. 2018b. Putrescent Whole Egg Solids Profile. Cornell Cooperative Extension, New York State 

Integrated Pest Management Program.

_____. 2018c. Sodium lauryl sulfate profile Active ingredient eligible for minimum risk pesticide use. New 

York State Integrated Pest Management Program Cornell Cooperative Extension.

_____. 2018d. Potassium Sorbate profile Active Ingredient eligible for minimum risk pesticide use. New 

York State Integrated Pest Management Program Cornell Cooperative Extension.

_____. 2018e. Dried blood profile Active ingredient eligible for minimum risk pesticide use. New York State 

Integrated Pest Management Program Cornell Cooperative Extension.

_____. 2018f. Garlic and garlic oil profile Active ingredient eligible for minimum risk pesticide use. New 

York State Integrated Pest Management Program Cornell Cooperative Extension.

_____. 2018g. Thyme and thyme oil profile Active ingredient eligible for minimum risk pesticide use. New 

York State Integrated Pest Management Program Cornell Cooperative Extension.

Baker, B.P., J.A. Grant, and R. Malakar-Kuenen. 2018. Cloves & Clove Oil Profile Active Ingredient Eligible 

for Minimum Risk Pesticide Use. New York State Integrated Pest Management Program Cornell 

Cooperative Extension.

Cohen, S.M., G. Eisenbrand, S. Fukushima, N.J. Gooderham, F.P. Guengerich, S.S. Hecht, I. Rietjens, T.J. 

Rosol, J.M. Davidsen, C.L. Harman, V. Lu, and S.V. Taylor. 2021. FEMA GRAS assessment of natural 

flavor complexes: Origanum oil, thyme oil, and related phenol derivative-containing flavoring 

ingredients. Food and Chemical Toxicology 155:112378.

Doleželová, P., S. Mácová, L. Plhalová, V. Pištěková, and Z. Svobodová. 2011. The acute toxicity of clove 

oil to fish Danio rerio and Poecilia reticulata. Acta Veterinaria Brno 80:305-308.

Ebert, T.A., P.G. Kevan, B.L. Bishop, S.D. Devan, and R.A. Downer. 2007. Oral toxicity of essential oils and 

organic acids fed to honey bees (Apis mellifera). Journal of Apicultural Research and Bee World 

46:220-224.

ECHA. 2013. Committee for Risk Assessment (RAC) Annex 1 Background document to the opinion 

proposing harmonised classification and labeling at EU level of potassium sorbate. European 

Chemicals Agency, Helsinki, Finland.

Genovese, A.G., M.K. McLean, and S.A. Khan. 2012. Adverse reactions from essential oil-containing natural 

flea products exempted from Environmental Protection Agency regulations in dogs and cats. 

Journal of Veterinary Emergency and Critical Care 22:470-475.
30

IARC. 2023. IARC Monographs on the identification of carcinogenic hazards to humans. 

https://monographs.iarc.who.int/agents-classified-by-the-iarc/ accessed 06/13/2023.

Le Coz, C.J., and M. Abensour. 2005. Occupational contact dermatitis from potassium sorbate in milk 

transformation plant. Contact Dermatitis 53:176-177.

Lindberg, C.M., A.P. Melathopoulos, and M.L. Winston. 2000. Laboratory evaluation of miticides to control 

Varroa jacobsoni (Acari: Varroidae), a honey bee (hymenoptera: Apidae) Parasite. Apiculture and 

Social Insects 93:189-198.

Machial, C.M., I. Shikano, M. Smirle, R. Bradbury, and M.B. Isman. 2010. Evaluation of the toxicity of 17 

essential oils against Choristoneura rosaceana (Lepidoptera: Tortricidae) and Trichoplusia ni 

(Lepidoptera: Noctuidae). Pest Management Science 66:1116-1121.

Merck. 2023. The Merck Index Online. https://www.rsc.org/merck-index accessed.

National Research Council. 1983. Risk assessment in the Federal government: managing the process. 

National Academy Press, Washington, DC.

NIH. 2023a. Sodium dodecyl sulfate Compound Summary. 

https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-dodecyl-sulfate accessed 06/14/2023.

_____. 2023b. Thymol. Compound Summary. https://pubchem.ncbi.nlm.nih.gov/compound/Thymol 

accessed 06/14/2023.

_____. 2023c. Corn Oil. Compound Summary. https://pubchem.ncbi.nlm.nih.gov/compound/Corn%20Oil 

accessed 06/14/2023.

OECD. 1995. Sodium dodecyl sulphate. Screening Information Dataset (SIDS). Organisation for Economic 

Co-operation and Development.

Opdyke, D.L.J. 1975a. Clove Bud Oil. Food and Cosmetics Toxicology 13:761-763.

_____. 1975b. Clove Stem Oil. Food and Cosmetics Toxicology 13:765-767.

_____. 1978. Clove Leaf Oil Madagascar. Food and Cosmetics Toxicology Journal 16:695.

Pochop, P.A., J.L. Cummings, C.A. Yoder, and J.E. Steuber. 1998. Comparison of white mineral oil and corn 

oil to reduce hatchability in ring-billed gull eggs. Proceedings of the Vertebrate Pest Conference 

18:411-413.

Prashar, A., I.C. Locke, and C.S. Evans. 2006. Cytotoxicity of clove (Syzygium aromaticum) oil and its major 

components to human skin cells. Cell Prolif 39:241-248.

Rojas-Armas, J., J. Arroyo-Acevedo, M. Ortiz-Sanchez, M. Palomino-Pacheco, A. Castro-Luna, N. RamosCevallos, H. Justil-Guerrero, J. Hilario-Vargas, and O. Herrera-Calderon. 2019. Acute and Repeated 

28-Day Oral Dose Toxicity Studies of Thymus vulgaris L. Essential Oil in Rats. Toxicology Research 

35:225-232.

Shalaby, S.E.M., M.M. El-Din, S.A. Abo-Donia, M. Mettwally, and Z.A. Attia. 2011. Toxicological affects of 

essential oils from eucalyptus Eucalyptus globules and clove Eugenia caryophyllus on albino rats. 

Polish Journal of Environmental Studies 20:429-434.

Sigma-Aldrich Corporation. 2023a. Clove Oil Safety Data Sheet C8392. Sigma-Aldrich Inc. St. Louis, 

Missouri, USA.

_____. 2023b. Corn Oil Safety Data Sheet. Sigma-Aldrich Inc., St. Louis, Missouri, USA.

Stroh, J., M.T. Wan, M.B. Isman, and D.J. Moul. 1998. Evaluation of the acute toxicity to juvenile pacific 

coho salmon and rainbow trout of some plant essential oils, a formulated product, and the carrier. 

Bulletin of Environmental Contamination & Toxicology 60:923-930.

Trent, A., D.L. Nolte, and K. Wagner. 2001. Timber Tech Tips: Comparison of Commerial deer repellents. 

U.S. Department of Agriculture, Forest Service, Technology & Development Program.

Tworkoski, T. 2002. Herbicide effects of essential oils. Weed Science 50:425-431.

USDA. 2001. Wildlife Services Tech Note. Egg Oil: An avian population control tool. U.S. Department of 

Agriculture, Animal and Plant Health Inspection Service.
31

_____. 2021. Wildlife Services Tech Note: Sodium Lauryl Sulfate: European starling and blackbird wetting 

agent. U.S. Department of Agriculture, Animal and Plant Health Inspection Service.

USEPA. 1991. Reregistration Eligibility Decision (RED) Dried Blood. U.S. Environmental Protection Agency, 

Office of Pesticide Programs.

_____. 1992. Reregistration Eligibility Document: Putrescent Whole Egg Solids. 

https://www3.epa.gov/pesticides/chem_search/reg_actions/reregistration/red_PC-105101_1-

Jun-92.pdf accessed March 23, 2023.

_____. 2003. Recommendations for tolerance reassessment potassium sorbate. U.S. Environmental 

Protection Agency Office of Prevention, Pesticides and toxic substances.

_____. 2009a. FIFRA Enforcement Response Policy Federal Insecticide, Fungicide, and Rodenticide Act. 

Waste and Chemical Enforcement Division, Office of Civil Enforcement, Office Of Enforcement 

and Compliance Assurance, United States Environmental Protection Agency.

_____. 2009b. Preliminary Human Health Assessment for the Registration Review of Capsaicin, 

Registration Review Case #: 4018 (EPA-HQ-OPP-2009-0121-0003). U.S. Environmental Protection 

Agency, Office of Pesticides and Toxic Substances.

_____. 2009c. Registration Review: Product Chemistry Data Review for the Repellent Garlic Oil. 

https://www.regulations.gov/document/EPA-HQ-OPP-2009-0113-0004 accessed 03/09/2023.

_____. 2009d. Lauryl sulfate salts summary document: Registration review Docket Number EPA-HQ-OPP2009-0727. U.S. Environmental Protection Agency Prevention, Pesticides and Toxic Substances.

_____. 2009e. Summary of Product chemistry, environmental fate, and ecotoxicity data lauryl sulfate for 

registration review (Docket number EPA-HQ-OPP-2009-0727-0004). U.S. Environmental 

Protection Agency, Office of Prevention, Pesticides, and Toxic Substances.

_____. 2010a. Garlic Oil FInal Registration Review Decision Case 4007. 

https://www.regulations.gov/document/EPA-HQ-OPP-2009-0113-0011 accessed 03/09/2023.

_____. 2010b. Lauryl Sulfate Salts Final Work Plan & Proposed Registration Review Final Decision Case 

4061 Docket Number EPA-HQ-OPP-2009-0727.

_____. 2011a. Preliminary Human Health Assessment for the Registration Review of Putrescent Whole 

Egg Solids (EPA-HQ-OPP-2010-0726-0004). U.S. Environmental Protection Agency, Office of 

Pesticides and Toxic Substances.

_____. 2011b. Ecotoxicity Assessment for Putrescent Egg Solids Registration Review (EPA-HQ-OPP-2010-

0726-0006). U.S. Environmental Protection Agency, Office of Chemical Safety and Pollution 

Prevention.

_____. 2011c. Chemistry Scoping Document for Registration Review of Putrescent Whole Egg Solids (EPAHQ-OPP-2010-0726-0005). U.S. Environmental Protection Agency.

_____. 2011d. Putrescent Whole Egg Solids Final Work Plan, Registration Review Case Number 4079 (EPAHQ-OPP-2010-0726-0003). U.S. Environmental Protection Agency.

_____. 2018. Putrescent Whole Egg Solids, Interim Registration Review Decision, Case Number 4079 EPAHQ-OPP-2010-0726-0009. U.S. Environmental Protection Agency.

_____. 2019. Human health dietary risk assessment to support an exemption from the requirement of a 

tolerance for sodium lauryl sulfate (Docket Number EPA-HQ-OPP-2018-0763-0004). U.S. 

Environmental Protection Agency, Office of Chemical Safety and Pollution Prevention.

_____. 2020. Flower Oils (PC Codes: 004902, 021901, 025000, 040500, 040502, 040503, 040517, 102701, 

129029, 129030, 129035, 597501, and 597800) Interim Registration Review Decision Case 

Number 8202. U.S. Environmental Protection Agency, Biopesticides and Pollution Prevention 

Division.

_____. 2022a. Overview of Risk Assessment in the Pesticide Program. https://www.epa.gov/pesticidescience-and-assessing-pesticide-risks/overview-risk-assessment-pesticide-program accessed

December 15, 2022.
32

_____. 2022b. Garlic Oil PC Code 128827 Combined Preliminary Work Plan and Proposed Interim 

Registration Review Decision Case Number 4007. https://www.regulations.gov/document/EPAHQ-OPP-2021-0838-0002 accessed 03/09/2023.

_____. 2022c. Pesticide Product and Label System (PPLS): Lursect labels 

https://ordspub.epa.gov/ords/pesticides/f?p=113:6:::::P6_XCHEMICAL_ID:2255 accessed March 

23, 2023.

_____. 2023a. Sorbic acid, potassium salt. 

https://ordspub.epa.gov/ords/pesticides/f?p=113:6:::::P6_XCHEMICAL_ID:3916 accessed

07/26/2023.

_____. 2023b. Inert Use Information: InertFinder Pesticides. 

https://ordspub.epa.gov/ords/pesticides/f?p=INERTFINDER:1::::1 accessed 06/14/2023.

_____. 2023c. Sodium Lauryl Sulfate. 

https://ordspub.epa.gov/ords/pesticides/f?p=113:6:::::P6_XCHEMICAL_ID:3869 accessed

07/26/2023.

_____. 2023d. Conditions for Minimum Risk Pesticides. https://www.epa.gov/minimum-riskpesticides/conditions-minimum-risk-pesticides accessed 06/13/2023.

_____. 2023e. Thyme oil. 

https://ordspub.epa.gov/ords/pesticides/f?p=113:6:::::P6_XCHEMICAL_ID:3164 accessed

07/26/2023.

Velisek, J., Z. Svobodova, and V. Piackova. 2005a. Effects of clove oil anaesthesia on rainbow trout 

(Oncorhynchus mykiss). Acta Veterinaria Brno 74:139-146.

Velisek, J., Z. Svobodova, V. Piackova, L. Groch, and L. Nepejchalova. 2005b. Effects of clove oil anaesthesia 

on common carp (Cyprinus carpio L.). Veterinary Medicine - Czech 50:269-275.

Venarsky, M.P., and F.M. Wilhelm. 2006. Use of clove oil to anaesthetize freshwater amphipods. 

Hydrobiologia 568:425-432.
33

13 PREPARERS: WRITERS, EDITORS, AND REVIEWERS

13.1 APHIS WS Methods Risk Assessment Committee

Writers for "Use of Minimum Risk Pesticides Used in Wildlife Damage Management Risk 

Assessment":

Primary Writer: Shelagh DeLiberto 

Position: USDA-APHIS-Wildlife Services (WS), Operational Support Staff, Environmental 

Coordinator, Fort Collins, CO

Education: BA Biology and Environmental Science – Ithaca College; MS Wildlife Biology –

Colorado State University 

Experience: Twenty years of service in APHIS conducting wildlife research. Two years of 

experience in preparing categorical exclusions and environmental analyses in compliance 

with the National Environmental Policy Act.

Primary Writer: Emily Ruell

Position: USDA-APHIS-WS, NWRC, Registration Manager, Fort Collins, CO

Education: B.S. Zoology and Biological Aspects of Conservation – University of Wisconsin -

Madison; M.S. Ecology – Colorado State University (CSU); M.A. Political Science – CSU

Experience: Nine years of experience with WS NWRC preparing and reviewing vertebrate 

pesticide registration data submissions and other registration materials and providing 

pesticide regulatory guidance to WS, WS NWRC, and collaborators. Prior experience 

before joining APHIS includes seven years of conducting field and laboratory wildlife 

research at CSU and environmental policy research for the U.S. Geological Survey.

Writer/Editor: Thomas C. Hall

Position: USDA-APHIS-WS, Operational Support Staff, Staff Wildlife Biologist, Fort Collins, CO

Education: BS Biology (Natural History) and BA Psychology – Fort Lewis College; MS Wildlife 

Ecology – Oklahoma State University

Experience: Special expertise in wildlife biology, identification, ecology, and damage 

management. Thirty-eight years of service in APHIS Wildlife Services including operations 

and research in CO for research and OR, GU, CA, OK, and NV for operations conducting 

a wide variety of programs including bird damage research and management, livestock 

protection (predators and birds), invasive species management, wildlife hazard 

management at airports, property and natural resource protection including waterfowl, 

brown tree snake, feral swine, rodent, and beaver damage management. Researched, 

applied and supervised the use of repellents.

Editors/Contributors for "Use of Minimum Risk Pesticides Used in Wildlife Damage Management 

Risk Assessment":

Editor: Anthony D’Alessio

Position: USDA-APHIS-Policy and Program Development (PPD), Environmental and Risk 

Analysis Services (ERAS), Biological Scientist, Raleigh, NC
34

Education: Three years of undergraduate education in Agricultural and Resource Economics 

with a concentration in policy from the University of Maryland, College Park. 

Experience: Three years of relevant undergraduate coursework and internship experience with 

the APHIS preparing analyses in compliance with the Endangered Species Act and 

National Environmental Policy Act.

Editor: Andrea Lemay 

Position: USDA-APHIS-Policy and Program Development (PPD), Environmental and Risk 

Analysis Services (ERAS), Biological Scientist, Raleigh, NC

Education: BS Plant and Soil Science (Biotechnology) - University of Massachusetts; MS Plant 

Pathology -North Carolina State University 

Experience: Thirteen years of service in APHIS conducting risk analysis. Four years of 

experience in preparing environmental analyses in compliance with the National 

Environmental Policy Act.

Editor: Michael McCaskill

Position: USDA-APHIS-Policy and Program Development (PPD), Environmental and Risk 

Analysis Services (ERAS), Toxicologist, New Market, MD

Education: B.S. Environmental Science – University of Florida; MPH Industrial HygieneUniversity of South Carolina, Ph.D. Toxicology-Florida Agriculture and Mechanical 

University

Experience: Ten years of experience conducting human toxicological research at Florida 

Agriculture and Mechanical University, University of Nebraska Medical Center, and Tulane 

University. Four years of experience conducting human health and environmental 

toxicological risk assessments and assisting environmental compliance programs at the 

Florida Department of Health, Commonwealth of Pennsylvania, and USDA.

Data Contributor: Joey Millison

Position: USDA-APHIS-WS Information and Technology (IT), Junior Applications Developer

Education: Information and Technology coursework from various sources

Experience: Eleven years of experience in APHIS, WS Management Information System (MIS) 

Group. Retrieves WS field data from the MIS for writers, reviewers, and editors.

13.2 Internal Reviewers

USDA APHIS Wildlife Services

Reviewer: Jimmy Taylor

Position: USDA-APHIS-WS, NWRC, Assistant Director, Fort Collins, CO

Education: BS Forest Management (Wildlife Option) – Mississippi State University; MS Wildlife 

Ecology – Mississippi State University; PhD Forest Resources (emphasis in wildlife) –

Mississippi State University 

Experience: Twenty one years of service in APHIS conducting and supervising wildlife damage 

management research.
35

Reviewer: Nokota Harpster

Position: USDA-APHIS-WS Staff Wildlife Biologist for Pennsylvania WS

Education: Bachelor of Science-Wildlife Conservation from Juniata College.

Experience: 8 years working for WS.

Reviewer: Daniel Hirchert

Position: USDA-APHIS-WS, State Director, Sun Prairie, WI

Education: BS in Field Biology, University of Wisconsin

Experience: Twenty-eight years of service in wildlife damage management with APHIS Wildlife 

Services and Wisconsin Department of Natural Resources. Expertise in agricultural crop 

damage, aviation safety, urban wildlife conflicts and natural resource protection. 
36

APPENDIX TABLE A.1. The annual average number of gallons or pounds of minimum risk pesticides (MRPs) applied by APHISWS in WDM in FY11–FY15 for all products with the number of work tasks (WTs) associated with the applications.

*AR, CA, CO, GA, ID, IL, IN, KS, KY, MD, MI, MN, MO, NC, NE, NV, NY, OR, PA, TN, TX, VA, VT, WA, WI, & WV plus DC

MRP Active Ingredient(s) (% w/w, CAS 

Number) Product Applied (gal/lb) WTs States Used

Distributed

(gal/lb) WTs States Used

Putrescent Whole Egg Solids (1.12%; 51609-

52-0)

Cloves (0.54%; N/A)

Garlic Oil (0.03%; 8000-78-0)

Shot-Gun® Repels-All® (granules, 

Bonide® Products LLC) - - - 0.6 lb 0.2 NH

Putrescent Whole Egg Solids (1.040%; 

51609-52-0)

Garlic (0.374%; N/A)

Sodium Lauryl Sulfate (0.040%; 151-21-3)

Potassium Sorbate (0.495%; 24634-61-5)

Thyme Oil (0.010%; 8007-46-3)

Liquid Fence® Deer & Rabbit 

Repellent

(liquid, The Liquid Fence Co., now 

Spectrum Brands, Inc.)

- - - 7.8 gal 7.7 NH

Dried Blood (12.0%; 68911-49-9)

Plantskydd® Repellent

(liquid, Tree World® Plant Care 

Products Inc.)

- - - 0.7 gal 2.4 NH

Dried Blood (100%; 68911-49-9)

Plantskydd® Repellent

(powder concentrate, Tree World®

Plant Care Products Inc.)

- - - 11.4 lb 6.6 NH

Dried Blood (100%; 68911-49-9) DeerOff® Deer Repellent (liquid) - - - 3.7 gal 3.4 NH

Sodium Lauryl Sulfate (28–30%; 151-21-3) Multiple 1 gal. 0.2 IL - - -

Corn Oil (100%; 8001-30-7) Multiple 38.5 gal. 515 27* - - -