BIOPESTICIDES REGISTRATION ACTION DOCUMENT

Tea Tree Oil

 PC Code : 028853

U.S. Environmental Protection Agency

Office of Pesticide Programs

Biopesticides and Pollution Prevention Division

May 23, 2014
Tea Tree Oil

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TABLE OF CONTENTS

I. EXECUTIVE SUMMARY:................................................................................................ 5

II. ACTIVE INGREDIENT OVERVIEW.............................................................................. 6

III. REGULATORY BACKGROUND...................................................................................... 6

A. Classification ........................................................................................................................ 6

B. Food Clearances/Tolerances............................................................................................... 6

IV. RISK ASSESSMENT ......................................................................................................... 7

A. Active Ingredient Characterization.................................................................................... 7

B. Human Health Assessment.................................................................................................. 8

1. Toxicology ......................................................................................................................................................8

2. Dose Response Assessment .........................................................................................................................13

3. Food Quality Protection Act (FQPA) Considerations..............................................................................13

4. Occupational, Residential, School and Day Care Exposure and Risk Characterization ......................20

5. Aggregate Exposure from Multiple Routes Including Dermal, Oral, and Inhalation...........................22

6. Cumulative Effects......................................................................................................................................23

7. Risk Characterization .................................................................................................................................23

C. Environmental Assessment ............................................................................................... 23

1. Ecological Hazards......................................................................................................................................23

2. Environmental Fate and Ground Water Data..........................................................................................23

3. Ecological Exposure and Risk Characterization ......................................................................................24

4. Endangered Species Assessment ................................................................................................................24

D. Efficacy Data ..................................................................................................................... 24

V. RISK MANAGEMENT DECISION................................................................................ 25

A. Determination of Eligibility for Registration .................................................................. 25

B. Regulatory Decision........................................................................................................... 25

C. Environmental Justice ....................................................................................................... 26

VI. ACTIONS REQUIRED BY REGISTRANTS................................................................. 26

A. Reporting of Adverse Effects............................................................................................ 26

B. Reporting of Hypersensitivity Incidents.......................................................................... 26
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VII. APPENDIX A. DATA REQUIREMENTS (40 CFR PART 158-SUBPART U).......... 26

VIII. APPENDIX B..................................................................................................................... 32

IX. APPENDIX C.................................................................................................................... 32

X. GLOSSARY OF ACRONYMS AND ABBREVIATIONS ............................................. 33
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BIOPESTICIDES REGISTRATION ACTION DOCUMENT (BRAD) TEAM

Branch Chief

Linda A. Hollis, M.S.

Product Chemistry/Human Health Effects/Nontarget Organisms

Angela L. Gonzales, Biologist

Regulatory Action Leader

Colin G. Walsh, M.S., Biologist
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I. EXECUTIVE SUMMARY:

Tea tree oil is a new biochemical pesticide active ingredient intended for use as a 

fungicide/bactericide on the following food commodities: leafy vegetables (group 4), fruiting 

vegetables (group 8), cucurbit vegetables (group 9), berries (group 13), cereal grains (group 15), 

avocado, banana, mango, papaya, plantain, kiwi, and passion fruit. The active ingredient is 

extracted from the leaves and terminal branches of the tea tree (Melaleuca alternifolia), which is 

a member of the plant family Myrtaceae and is indigenous to Australia, New Zealand, and 

Southeast Asia. Tea tree oil is composed of approximately 100 different compounds which 

consist of terpene hydrocarbons, primarily monoterpenes, sesquiterpenes, and their associated 

alcohols. The active ingredient has antifungal properties and is effective against a broad 

spectrum of plant-pathogenic fungi, but the mode of action is not clearly understood. It has been 

shown to affect cell respiration and alter cell membrane structure in yeast. Based on this 

information, the Agency considers the mode of action to be nontoxic.

The Biopesticides and Pollution Prevention Division (BPPD) has reviewed all of the data and 

other information submitted in support of the registration of tea tree oil as a fungicide/bactericide 

under Section 3(c)(5) of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), and 

has determined that the current data requirements (40 CFR part 158.2010 through 158.2070) for 

registration of a biochemical pesticide have been satisfied. Given that tea tree oil is of low 

toxicity and presents little, if any, risks to humans, including infants and children, and the 

environment, the U.S. Environmental Protection Agency (EPA or the Agency) has concluded 

that it is in the best interest of the public to issue registrations for the manufacturing-use product 

(MP), Tea Tree Oil Technical (EPA File Symbol No. 86182-E), and the end-use product (EP), 

Timorex Gold (EPA File Symbol No. 86182-R), which contain this new active ingredient, tea 

tree oil. The basis for this decision is described in more detail in section IV of this Biopesticide 

Registration Action Document (BRAD). 

On October 1, 2009, EPA announced a policy to provide a more meaningful opportunity for the 

public to participate on major registration decisions before they occur. According to this policy, 

EPA provides a public comment period prior to making a registration decision for the following 

types of applications: new active ingredients, first food use, first outdoor use, first residential 

use; and any registration decisions for which the Agency believes there may be substantial public 

interest. 

Consistent with the policy of making registration actions more transparent, tea tree oil is subject 

to a 15-day comment period as a “new active ingredient.” EPA has established a comment period 

of 15 days on the basis of tea tree oil’s low toxicity, the determination that tea tree oil presents 

low risk of any adverse effects to human health and the environment, and critical need for this 

active ingredient. The notice for this comment period includes the draft BRAD and draft product 

labels for the MP, Tea Tree Oil Technical, and EP, Timorex Gold, which contain this new active 

ingredient, tea tree oil. The docket identification (ID) number is EPA-HQ-OPP-2009-0440. The 

Agency believes that based on the risk assessment and information submitted in support of the 

registration of the MP and EP containing tea tree oil, it is in the best interests of the public to 

issue the registration for Tea Tree Oil Technical and Timorex Gold. The basis for this decision 

can be found in the risk assessment for tea tree oil, which is characterized in this BRAD.
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For definitions of scientific terms, please refer to http://www.epa.gov/pesticides/glossary/.

II. ACTIVE INGREDIENT OVERVIEW

Common Name: Tea Tree Oil

 Chemical Names: Tea Tree Oil; Oils, tea-tree

Trade & Other Names: Tea Tree Oil Technical

 CAS Registry Number: 68647-73-4

OPP Chemical Code: 028853

Type of Pesticide: Fungicide/Bactericide

III. REGULATORY BACKGROUND

On April 10, 2009, EPA received an application filed by Technology Sciences Group, Inc. 

(TSG), 1150 18th Street, NW, Suite 1000, Washington, DC 20036, on behalf of Biomor Israel,

Ltd. (Biomor), P.O. Box 81, Qatzrin, 12900 Israel, to register the products, Timorex Gold (EPA 

File Symbol No. 86182-R) and Tea Tree Oil Technical (EPA File Symbol No. 86182-E),

containing the new biochemical active ingredient, tea tree oil. A notice of receipt (NOR) of this 

application, allowing for a 30-day comment period, was published in the Federal Register on

July 22, 2009 (74 FR 36215). No comments were received following this publication.

A. Classification

On October 28, 2004, EPA’s Biochemical Classification Committee determined that tea tree oil

is a biochemical pesticide. The biochemical classification committee indicated that tea tree oil is 

a fungicide/bactericide. The mode of action is not clearly understood, but has been shown to 

disrupt membranes of fungal/bacterial species. Tea tree oil is the essential oil of the Melaleuca 

tree (tea tree) and is rich in terpene alcohols (such as terpinen-4-ol and eucalpyptol). The oil is 

manufactured to contain at least 30% terpinen-4-ol (germicidal) and no more than 15% 

eucalpyptol (anti-fungal). The terpinen-4-ol is generally accepted to be the active component of 

tea tree oil. There is a long history of use of tea tree oil as an antiseptic and antifungal agent and 

it is formulated into creams, soaps, mouthwashes, toothpaste, and other cosmetic products.

B. Food Clearances/Tolerances 

The consultant, TSG on behalf of Biomor, filed a petition (PP 9F7558) proposing to establish an 

exemption from the requirement of a tolerance for residues of tea tree oil in or on all food 

commodities. A notice of filing (NOF), allowing for a 30-day comment period, was published in 
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the Federal Register on July 22, 2009 (74 FR 36200). No comments were received following this 

publication.

EPA determined during the review of the petition that the data and information submitted was 

insufficient to support an exemption from the requirement of a tolerance for residues of tea tree 

oil in or on all food commodities. However, as noted in the Risk Assessment section of this 

BRAD (Section IV), EPA has determined, based on the data submitted, that the active ingredient, 

tea tree oil, can be exempt from the requirement of a tolerance of residues in or on the following 

food commodities: leafy vegetables (group 4), fruiting vegetables (group 8), cucurbit vegetables 

(group 9), berries (group 13), cereal grains (group 15), avocado, banana, mango, papaya, 

plantain, kiwi, and passion fruit.

IV. RISK ASSESSMENT

A. Active Ingredient Characterization

Tea tree oil is a new biochemical pesticide active ingredient intended for use to prevent and 

control diseases such as powdery mildew, Botrytis, and black sigatoka in horticultural and 

agricultural crops. The active ingredient has antifungal properties and is effective against a broad 

spectrum of plant-pathogenic fungi, but the mode of action is not clearly understood. It has been 

shown to affect cell respiration and alter cell membrane structure in yeast. Based on this 

information, the Agency considers the mode of action to be nontoxic.

The active ingredient is extracted from the leaves and terminal branches of the tea tree 

(Melaleuca alternifolia) which is a member of the plant family Myrtaceae and is indigenous to 

Australia, New Zealand, and Southeast Asia. Tea tree oil is composed of approximately 100 

different compounds which consist of terpene hydrocarbons, primarily monoterpenes, 

sesquiterpenes, and their associated alcohols. These biogenic chemicals are aromatic 

hydrocarbons which are found in the essential oils of a multitude of plants and are characterized 

by their high volatility and low aqueous solubility (EPA, 2010). The composition of tea tree oil 

used in commerce is regulated by an international standard (ISO 4730, International 

Organization for Standardisation), which sets maximum and minimum limits for 14 of its 

components. Of the several varieties or chemotypes of tea tree oil, only the terpinen-4-ol 

chemotype, which contains 30-48% terpinen-4-ol, will be used as the TGAI in the proposed MP, 

Tea Tree Oil Technical (EPA File Symbol No. 86182-E). ISO 4730 defines the main ingredients 

as α-terpinine (5-13%); 1,8-cineole (traces to 15%); γ-terpinine (10-28%); p-cymene (0.5-12%); 

and terpinen-4-ol (30-48%). The specifications for all 14 ingredients are listed in Table 1 below. 

TABLE 1. Specifications of Tea Tree Oil Components per ISO Standard 47301

Name CAS No. Minimum % Maximum %

Terpinen-4-ol 562-74-3 30 48

γ-Terpinine 99-85-4 10 28

α-Terpinine 99-86-5 5 13

α-Terpineol 98-55-5 1.5 8

α-Terpinolene 586-62-9 1.5 5

α-Pinene 80-56-8 1 6
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p-Cymene 99-87-6 0.5 8

1,8-Cineole 470-82-6 Trace 15

Limonene 138-86-3 0.5 1.5

Aromadendrene 489-39-4 0.5 3

δ-Cadinene 483-76-1 Trace 3

Sabinene 3387-41-5 Trace 3.5

Globulol 489-41-8 Trace 1

Viridiflorol 552-02-3 Trace 1

Ledene Trace 3

1

from MRID 47730409

Humans are already naturally exposed to the major constituents of tea tree oil (terpinen-4-ol, γterpinene, 1,8-cineole, and α-terpinene) in the diet as they are found in herbs, spices, citrus and 

some vegetables (EPA, 2014). Humans are also exposed to the major constituents of tea tree oil 

as food additives in the diet, as they have been approved as substances that may directly be 

added to food by the U.S. Food and Drug Administration (FDA) under 21 CFR § 172.515(b). 

Tea tree oil is comprised of primarily terpenes and their associated alcohols which are found in 

the environment as they are emitted by and present in a variety of plant species and water 

sources. Additionally, tea tree oil has a long history of use as a remedy for acne, eczema, skin 

infections, cold sores, blisters, and warts; and is used in cosmetic and personal care products 

such as shampoo, toothpaste, mouthwash, deodorants, lotions, and bath oils, as well as in animal 

care products (EPA, 2010).

Descriptions of the product formulation and production process, formation of impurities, and 

physical and chemical characteristics of tea tree oil were examined by BPPD and found to be 

acceptable in meeting current guideline standards.

All product chemistry data requirements for registration of tea tree oil have been satisfied. 

For more information regarding product chemistry data requirements, refer to Tables 6 and 7 in 

Appendix A. 

B. Human Health Assessment

1. Toxicology

For acute toxicity data requirements, toxicity categories are assigned based on the hazard(s) 

identified from studies and/or information on file with the Agency. The active ingredient is 

classified into Toxicity Category I, II, III, or IV where Toxicity Category I indicates the highest 

toxicity and Toxicity Category IV indicates the lowest toxicity. 

Adequate mammalian toxicology data/information is available to support registration of tea tree 

oil. All toxicology data requirements for tea tree oil have been satisfied.

a. Acute Toxicity

Acute toxicity testing is required to: 1) determine systemic toxicity from acute exposure via the 
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dermal, inhalation, and oral routes; 2) determine irritant effects from exposure to the eyes; and 3) 

determine the potential for skin sensitization (allergic contact dermatitis). 

A Tier I primary dermal irritation study in rabbits submitted and reviewed showed that tea tree 

oil is corrosive to the skin at undiluted concentrations (toxicity category I). Based on the results 

in the primary dermal irritation study, the primary eye irritation and dermal sensitization data 

requirements were waived; therefore, tea tree oil is classified as corrosive to the eye (toxicity 

category I). Tea tree oil is a toxicity category III (slightly toxic) compound via the acute oral and 

dermal toxicity routes of exposure based on a median lethal dose (LD50) of 1,752 mg/kg body 

weight in rats and a LD50 of greater than 2,000 mg/kg in rabbits, respectively. Tea tree oil is a

toxicity category IV (not toxic) compound for acute inhalation toxicity based on a medial lethal 

concentration (LC50) of 3.64 mg/L.

For more information regarding acute toxicity data requirements, refer to Table 8 in Appendix A. 

b. Subchronic Toxicity 

Subchronic data are required to determine a no-observed-effect-level (NOEL) and any toxic 

effects associated with repeated or continuous exposure to a test substance for a period of 90 

days via the oral, dermal, and inhalation routes of exposure. 

A 90-day oral toxicity study (OCSPP 870.3100) was conducted on tea tree oil and submitted in 

MRID 48598702. Adequate supportive information regarding homogeneity testing of the test 

substance was submitted in MRID 48878202. Tea tree oil was administered to Wistar rats by 

gavage at dosages of 0 (peanut oil), 30, 60 or 120 mg/kg/day. An additional 20 rats were 

included in the high dose group, and an additional 10 rats were included in the control group. To 

determine the reversibility of any effects observed, 10 rats from the high dose group and 5 rats 

from the control group were sacrificed 14 days and 28 days after completion of the 90-day 

dosing period. No mortality was observed in male rats. Two moribund females in the high dose 

group were sacrificed during the treatment period. At all dose levels salivation was observed 

which persisted for about 30 minutes after dosing. Salivation incidences were dose-related. No 

treatment-related effects on body weight and body weight gain were observed. Toxicologically 

relevant hematological, clinical chemistry, or urinalysis findings were not noted at any dose 

level. In the high dose group, some motor activity measurements were statistically (p≤0.05) 

affected in both sexes; however, the toxicological significance of these observations is unclear as 

there was no correlation with abnormal functional observations. Statistically significant increases 

in liver to body weight ratios at the mid- and high-dose levels (+11% and +9%, respectively) 

were noted in females, and a significant increase in ovary to body weight ratio was noted in the 

28-day high dose recovery group (+31%). There was no microscopic correlation for the organ 

weight findings in females. Flaccid testes, some with a small appearance, were observed in highdose males (4/10 at the end of treatment; 2/10 after the 14-day recovery period; 8/10 after the 28-

day recovery period). Absolute organ weight and organ-to-body-weight ratios were significantly 

reduced in the testes and epididymides of males in the high-dose 28-day recovery group. These 

findings were microscopically associated with degenerative changes in the seminiferous tubules 

(loss of germ cells, formation of multinucleated germ cells, presence of cell debris in tubular 

lumen, atrophic appearance, and sertoli cell vacuolation). The testicular effects occurred at the 
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same or higher rate of incidence with an overall greater degree of severity in the high dose 

animals in the 14-day and 28-day recovery groups. Sperm granulomas and cellular debris in the 

lumen (inflammation involving epididymal lumen and interstitium with the presence of large 

zones of spermatozoa surrounded by a zone of macrophages, giant cells and fibroblasts) were 

observed in the epididymides of high dose males at the end of the 90-day treatment period. The 

incidence of sperm granulomas peaked in the 14-day recovery group, but the incidence and 

severity of cellular debris in the epididymal lumen increased in the 14- and 28-day recovery 

groups. Minimal cell debris was observed in the lumen of the epididymides in 1/10 male rats 

dosed at 60 mg/kg/day. No treatment-related histological changes were observed in males dosed 

at 30 mg/kg/day. Statistically significant treatment-related effects on sperm motility, sperm 

morphology, and epididymal sperm counts were observed at the high dose level at the end of the 

treatment period and in the 14- and 28-day recovery groups. Sperm counts were significantly 

lower relative to controls in the mid-dose group, and there was a significant decrease in sperm 

motility and an insignificant increase in abnormal sperm at this dose level. Based on these data, 

the lowest-observed-adverse-effect level (LOAEL) of tea tree oil in rats was 60 mg/kg/day based 

on testicular toxicity in males and increased liver to body weight ratios in females. The noobserved-adverse-effect level (NOAEL) is 30 mg/kg/day for males and females (EPA, 2013).

A 90-day dermal toxicity study was not submitted and is not required. Exposure via the dermal 

route is not anticipated due to the following: 1) prolonged dermal exposure is not expected 

because the product is not purposely applied to the skin and handlers/applicators are required to 

wear appropriate personal protective equipment (PPE); 2) a 4-hour restricted-entry interval (REI)

requirement has been included on the proposed EP label which will further mitigate exposure; 

and 3) tea tree oil has a long history of use in a variety of dermally-applied products, including 

shampoo, deodorants, lotions, and antifungal treatments. In a non-guideline 30-day dermal 

irritation study on rabbits (MRID 47730404), undiluted tea tree oil caused severe irritation to the 

skin on the first day of the study. For the remainder of the study, a 25% solution in paraffin oil 

was applied to the skin which did not result in visible irritation; however, non-specific 

microscopic dermatitis consistent with irritation was observed (EPA, 2013).

A 90-day inhalation toxicity study was not submitted for tea tree oil. In lieu of a study, the 

applicant cited the data from the 90-day oral toxicity study (MRID 48598702). Due to the use 

pattern of the active ingredient as a spray and the volatility of the constituents of tea tree oil, 

exposure to handlers/applicators is possible. There are no PPE requirements regarding mitigation 

of inhalation exposure on the proposed EP label. A route to route extrapolation using the default 

assumption that 100% of the tea tree oil is absorbed into the body has been employed. The 

Agency is confident that this approach is protective of potential repeat exposure inhalation 

toxicity for the following reasons: 1) tea tree oil is classified into Toxicity Category IV for acute 

inhalation toxicity and Toxicity Category III for acute oral toxicity; and 2) humans are already 

exposed to the constituents of tea tree oil as the oil is used in a variety of dermally-applied 

cosmetic and pharmaceutical products. Moreover, five of the main components of tea tree oil

(terpinen-4-ol, γ-terpinine, α-terpinine, p-cymene, and 1,8-cineole) are all approved for use by 

the FDA as direct food additives under 21 CFR 172.515. Further, in an occupational risk 

assessment conducted for applicators and handlers (who may be exposed via inhalation to tea 

tree oil), margins of exposure (MOEs) were derived and were significantly higher than the 

Agency’s level of concern (LOC) of 100 (MOEs ranged from 4,900 to 150,000). Because the 
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MOEs were significantly higher than the LOC, the Agency believes that an adequate margin of 

safety has been achieved to account for any potential difference in toxicity from oral versus 

inhalation exposure (EPA, 2013).

For more information regarding the subchronic toxicity data requirements, refer to Table 8 in

Appendix A. 

 c. Developmental Toxicity and Mutagenicity

A developmental toxicity study conducted on tea tree oil was submitted in MRID 49166401. In 

the study, Wistar rats were administered doses of tea tree oil by gavage at 0, 30, 60, or 120 

mg/kg/day from day 5 to day 19 of gestation. Each treatment group consisted of 24 female rats; 

the control group which received peanut oil, the test substance vehicle, also consisted of 24 

female rats. Initially, rats were dosed at 75, 150, and 300 mg/kg/day; however, there was a 

mortality on day two of treatment in the high dose group and treatment related clinical signs in 

the mid- and high-dose groups. Consequently, doses were reduced to 30, 60 and 120 mg/kg/day. 

At the start of treatment, animals were approximately 13-15 weeks old, within a weight range of 

approximate 224g ± 15g and healthy in appearance. Animal acclimatization, housing, diet, and 

water supply were reported adequately. Test substance characterization and preparation was also 

reported adequately. Animals were dosed once a day at approximately the same time each day. 

Physical examinations occurred on day 0 of gestation and at weekly intervals during the 

gestation period. Clinical observations occurred at least twice a day on treatment days (pre- and 

post-dosing) and once a day on other days. Body weights were measured on days 0, 3 and 5, 8, 

11, 14, 17, and 20 after mating and food consumption was measured throughout the study. 

Animals were sacrificed on day 20 after mating under isoflurane anesthesia. Gross necropsy was 

performed on all rats, which consisted of external observation and examination of thoracic and 

abdomen viscera and examination of uterine contents. Gravid uterine weights, the number of 

corpora lutea in each ovary, the number of implantation sites, the number of early and late 

resorptions sites, the number of live and dead fetuses, individual fetal body weights, fetal sex,

and the fetal sex ratio were recorded. Fetuses were also examined for external abnormalities, 

visceral organ abnormalities and skeletal development and abnormalities. Statistical analyses of 

the data were provided in the study. Significant reductions in maternal body weight gain and 

food intake were observed during the treatment period in the mid- and high-dose groups and 

throughout gestation in the high dose group. These observations were considered treatment 

related. No gross pathological findings were observed in the dams in any group. At all dose 

levels, mean gravid uterine weights, the number of corpora lutea, the number of implantations,

and pre and post-implantation losses were all statistically comparable to the control group. 

Significant resorption was observed in dams in the high dose group when compared to the 

control group. At all dose levels, the total number of fetuses, mean litter size, number of live 

fetuses, and the sex ration were all statistically comparable to the control group. Mean fetal body 

weights of males, females, and total fetuses were significantly reduced at the mid and high dose 

level; however, the weights of the fetuses in the mid dose group were comparable to historical 

control data. Any fetal anomalies and abnormalities that were observed were routinely observed 

in rat fetuses, were comparable to the control group or were comparable to historical control 

data; none were considered treatment related. Based on the results of the study, the maternal 

NOAEL is 30 mg/kg/day and the LOAEL is 60 mg/kg/day based on reduced body weight gain 
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and food consumption. The developmental NOAEL is 60 mg/kg/day and the LOAEL is 120 

mg/kg/day based on reduced fetal body weight (EPA, 2014).

In a study published in the New England Journal of Medicine (Henley, 2007), study authors 

reported that repeated topical exposure to lavender and tea tree oils may cause prepubertal 

gynecomastia in boys. Three prepubertal boys who were otherwise healthy and had normal 

serum concentrations of endogenous steroids exhibited gynecomastia that coincided with the 

topical application of products that contained lavender and tea tree oils. The effect resolved in 

each boy shortly after the use of the products was discontinued. The authors also reported that 

studies in human cell lines indicated that lavender and tea tree oils had estrogenic and 

antiandrogenic activities. Although the study suggests that exposure to topical applications of 

products containing lavender and tea tree oils may result in gynecomastia in boys, the Agency 

has concluded that the uses of tea tree oil as a pesticide will not result in unreasonable adverse 

effects to this population subgroup. This conclusion is based upon the following: 1) tea tree oil 

will not be applied topically to the skin. The active ingredient will be applied to crops as an 

agricultural use; thus, exposure is mainly anticipated to be via the oral route, 2) dietary exposure 

to tea tree oil as a pesticide is anticipated to be minimal as it degrades rapidly in the 

environment, 3) dermal exposure is not anticipated to result in risk as occupational exposure 

assessments (see subchronic toxicity section above) indicate MOEs that do not exceed the 

Agency’s level of concern, and 4) humans are already exposed to the constituents of tea tree oil 

as they are found naturally in the diet, are used as food additives, and are found in a variety of 

cosmetic and pharmaceutical products. 

A Tier I mutagenicity study [in vitro reverse gene mutation assay (Ames) using Salmonella 

typhimurium strains TA98, TA100, and TA102 (MRID 47730404)] showed that tea tree oil did 

not increase the number of revertants at doses of <50 μg in the presence or absence of S9 

metabolic activation. A Tier II mutagenicity study [in vivo mammalian erythrocyte micronucleus 

assay (MRID 47730407)] showed that tea tree oil did not produce a statistically significant 

increase in the frequency of micronucleated polychromatic erythrocytes in bone marrow of mice 

given oral doses of 1000-1750 mg/kg body weight. Therefore, under the conditions of both 

assays, tea tree oil is considered to be non-mutagenic.

For more information regarding prenatal developmental and mutagenicity data requirements, 

refer to Table 8 in Appendix A. 

d. Tier II/Tier III 

Tiers II and III data were not required due to the nature of the active ingredient and its intended 

uses in potential new EP products (fungicides/bactericides).

e. Effects on the Endocrine System

As required under Federal Food, Drug, and Cosmetic Act (FFDCA) section 408(p), EPA has 

developed the Endocrine Disruptor Screening Program (EDSP) to determine whether certain 

substances (including pesticide active and other ingredients) may have an effect in humans or 

wildlife similar to an effect produced by a “naturally occurring estrogen, or other such endocrine 
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effects as the Administrator may designate.” The EDSP employs a two-tiered approach to 

making the statutorily required determinations. Tier 1 consists of a battery of 11 screening assays 

to identify the potential of a chemical substance to interact with the estrogen, androgen, or 

thyroid (E, A, or T) hormonal systems. Chemicals that go through Tier 1 screening and are found 

to have the potential to interact with E, A, or T hormonal systems will proceed to the next stage 

of the EDSP where EPA will determine which, if any, of the Tier 2 tests are necessary based on 

the available data. Tier 2 testing is designed to identify any adverse endocrine related effects 

caused by the substance, and establish a dose-response relationship between the dose and the E, 

A, or T effect.

Between October 2009 and February 2010, EPA issued test orders/data call-ins for the first 

group of 67 chemicals, which contains 58 pesticide active ingredients and nine inert ingredients. 

This list of chemicals was selected based on the potential for human exposure through pathways 

such as food and water, residential activity, and certain post-application agricultural scenarios. 

This list should not be construed as a list of known or likely endocrine disruptors.

Tea tree oil is not among the group of 58 pesticide active ingredients on the initial list to be 

screened under the EDSP. Under FFDCA section 408(p) the Agency must screen all pesticide 

chemicals. Accordingly, EPA anticipates issuing future EDSP test orders/data call-ins for all 

pesticide active ingredients. 

For further information on the status of the EDSP, the policies and procedures, the list of 67 

chemicals, the test guidelines and the Tier 1 screening battery, please visit our website: 

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

2. Dose Response Assessment

The NOAEL of 30 mg/kg bw/day has been selected as the point of departure (POD) for the 

hazard and risk assessment. The NOAEL is based on toxic endpoints observed in the 90-day oral 

toxicity study. The POD is protective of developmental toxicity because the NOAEL in the 90-

day oral toxicity study is lower than the developmental (fetal) toxicity NOAEL of 60 mg/kg 

bw/day. 

3. Food Quality Protection Act (FQPA) Considerations

a. Dietary Exposure and Risk Characterization

Human exposure to tea tree oil may occur via dietary exposure to some treated commodities, 

although exposure is anticipated to be minimal. A risk assessment was conducted for tea tree oil, 

specifically for the residue of concern, terpinen-4-ol (the main constituent of tea tree oil), to 

assess potential risks (if any) from dietary exposure. The Agency has determined that there is 

reasonable certainty of no harm to humans when exposed to residues of the active ingredient 

(specifically, residues of terpinen-4-ol) from pesticidal use when label instructions are followed. 

This conclusion is based on the following: 1) although toxic endpoints have been identified in 

studies on tea tree oil, significant dietary exposure is not expected because tea tree oil is 

anticipated to degrade rapidly in the environment; 2) humans are already exposed to the 
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constituents of tea tree oil in the diet from foods that naturally contain the compounds and from 

foods to which the compounds have been added as food additives; and 3) quantitative dietary 

risk assessments suggest that dietary exposure to tea tree oil when used as a pesticide is not 

likely to pose unreasonable risk to the U.S. population in general, or sensitive subpopulations, 

including infants and children. A detailed discussion of how the Agency arrived at its conclusion 

is provided in the subsequent paragraphs.

Residues

Data on residues of the major constituents of tea tree oil (terpinen-4-ol, γ-terpinene, and 1,8-

cineole) in crop field trials indicate that when label instructions are followed, residues are not 

likely to be found on peppers, tomatoes, or bananas. Based on the available data, residues of the 

constituent terpinen-4-ol are likely to be found on peppers when tea tree oil is applied at higher 

application rates than those provided on the EP label. 

Residue data have been submitted for applications of products containing tea tree oil on 

tomatoes, peppers, and bananas (EPA, 2014). Analysis for residues of the three major 

components in the oil (terpinen-4-ol, γ-terpinene, and 1,8-cineole) was performed in the studies. 

No detectable residues (below the limit of quantification [LOQ]) were found in tomatoes at 

application rates higher than those on the proposed label (approximately three to seven times the 

proposed application rate). No detectable residues were found in bananas at the proposed 

application rate. Detectable residues of terpinen-4-ol only (maximum of 0.10 mg/kg at 24-hours) 

were found for up to 48-hours on peppers at a higher application rate than that proposed on the 

EP label, but no detectable residues of any components, including terpinen-4-ol, were found at 

the proposed application rate. 

Dietary Exposure from Natural Sources

Tea tree oil is not considered to be an edible oil; however, its major constituents are found in a 

variety of edible commodities (EPA, 2014). Humans are already naturally exposed to the major 

constituents of tea tree oil (terpinen-4-ol, γ-terpinene, 1,8-cineole, and α-terpinene) in the diet as 

they are found in herbs, spices, citrus, and some vegetables. Additionally, tea tree oil is 

comprised primarily of terpenes and their associated alcohols, which are found in the 

environment as they are emitted by and present in a variety of plant species and water sources. 

Quantitative and qualitative assessments regarding the natural occurrence of gamma-terpinene 

and 1,8-cineole have not been performed due to the lack of anticipated dietary exposure based on 

the absence of residues observed in the residue studies submitted by the applicant. Quantitative 

and qualitative assessments have been performed for terpinen-4-ol because residues of the 

compound were observed in the studies (albeit at a significantly higher application rate), thus the 

potential for dietary exposure (anticipated to be minimal) exists.

According to information on the U.S. Department of Agriculture – Agricultural Research Service 

(USDA-ARS) website (http://www.ars-grin.gov/duke/), terpinen-4-ol, gamma-terpinene, 1,8-

cineole, and alpha-terpinene (present in tea tree oil at 5-13%) are found in a variety of foods 

including spices, herbs, and citrus at varying concentrations (EPA, 2014). Terpinen-4-ol is also 

found in a variety of foods. The information provided in Table 2 below is a summary of the 
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approximate concentrations of terpinen-4-ol in foods.

Table 2. Approximate Concentrations of Terpinen-4-ol of Tea Tree Oil in Foods

Food Concentration Reference2

Raspberries 23-175 μg/kg (ppb)1 Malowicki, 2008

Apples and juices Concentration not quantified1 Ferreira, 2009; Schmutzer, 2011

Carrots Concentration not quantified1 Varming, 2004

Grapes Concentration not quantified1 Ugliano, 2008

Bananas Concentration not quantified1Jordán, 2000

Lemons 10,000-11,000 ppm USDA-ARS, 2014

Oranges and juices Concentration not quantified1 Eman, 2006; Gonzales-Mas, 2011; 

Qiao, 2008 

Tangerines and juices Concentration not quantified1 Miyazaki, 2011

Tomatoes Concentration not quantified1 Strano, 2011

Celery Concentration not quantified1; 1,000 ppm D’Antuono, 2002; USDA-ARS, 2014

Nutmeg 4,800 ppm (seed) USDA-ARS, 2014

Thyme oil Concentration not quantified but was 

identified as a major constituent of the oil

Kulkarni, 2013

Marjoram oil 0.2-51.7% of the oil depending on the 

source

Nowak, 2010

Peppercorn oils (Piper nigrum) 0-13.2% of the oils Orav, 2004

Licorice 0-72,000 ppm of the rhizome essential oil USDA-ARS, 2014

1Measured as a volatile component, generally using GC/MS

2

Information from MRIDs 49166403 and 49273601

Dietary Exposure from Food Additives

Terpinen-4-ol, γ-terpinene, and 1,8-cineole are all approved by the FDA for use for direct 

addition to food under 21 CFR 172.515(b). 

Dietary Risk Assessment

A quantitative risk assessment was conducted by the Agency using the available toxicity and 

residue data as inputs into the Agency’s Dietary Exposure Evaluation Model - Food Commodity 

Intake Database (DEEM-FCIDTM) to determine the potential for risk to the general U.S. 

population and sensitive subpopulations. DEEM-FCID is used by the Agency to provide 

probabilistic assessments of dietary pesticide exposure. The exposure assessment is then used to 

calculate dietary risk. Two separate types of conservative assessments were conducted, each of 

which is discussed below. 

Assessment # 1: DEEM-FCID using Tea Tree Oil residue data

For its assessment, the Agency used the measured residue of terpinen-4-ol from the field trials on 

peppers of 0.36 mg/kg (which was detected immediately after pesticide application) for all crops 

listed on the EP label since residue data are absent for all listed crops except for tomatoes, 

peppers, and bananas. Although the applicant has included a Pre-Harvest Interval (PHI) of 48 

hours on the label to mitigate risk (no residues of any major constituent for which analysis was 

conducted was found on treated crops at 48 hours), the Agency used the residue value found on 

treated peppers at time zero for its assessment. This conservative approach was utilized to 

increase confidence in the risk assessment because of the lack of residue data for the other crops 
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listed on the label. 

For the risk assessment, the reference dose (RfD) was calculated using the available toxicity data 

for tea tree oil. An RfD is an estimate (with consistent applications of generally order-ofmagnitude uncertainty factors) of daily exposure to the human population (including sensitive 

subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime. 

The uncertainty factor (UF) that is generally used is 100, which includes a 10X uncertainty factor 

for interspecies variation (extrapolation from animal data to humans) and a 10X uncertainty 

factor for intraspecies variation (variability between humans). The RfD is represented by the 

equation below:

Point of Departure (e.g., NOAEL)

RfD = ------------------------------------------

Uncertainty Factors (e.g., 100)

The RfD was calculated by dividing the NOAEL of 30 mg/kg/day from the 90-day oral toxicity 

study on tea tree oil by the uncertainty factor of 100, which resulted in the RfD of 0.3 mg/kg/day. 

To express risk, the percent of the RfD (%RfD) for each population subgroup is calculated by 

dividing the exposure (estimated in DEEM-FCID) by the RfD and multiplying the result by 

100%. For risk characterization, a %RfD or %PAD less than 100 is desired and indicates that the 

dietary risk for humans from pesticidal exposure is expected to be negligible. The %RfD is 

represented by the equation below:

Exposure

%RfD = ------------- * 100%

RfD

The results of the DEEM analysis and risk assessment are summarized in Table 3 below. 
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Table 3: DEEM-FCID Chronic Analysis for Tea Tree Oil (specifically terpinen-4-ol)

Population Subgroups

(age in years)

Estimated Dietary Exposure 

(mg/kg bw/day) Percent RfD

U.S. Population 0.002306 0.8%

Hispanics 0.002608 0.9%

Non-hispanics whites 0.002274 0.8%

Non-hispanic blacks 0.002066 0.7%

Non-hispanic/Non-white/Non-black 0.002520 0.8%

Nursing infants 0.002089 0.7%

Non-nursing infants 0.004178 1.4%

Females (13+) pregnant 0.002051 0.7%

Children (1-6) 0.005629 1.9%

Children (7-12) 0.003220 1.1%

Male 13-19 0.002190 0.7%

Females (13-19) not pregnant 0.001901 0.6%

Male (20+) 0.001913 0.6%

Females (20+) not pregnant 0.001756 0.6%

Seniors (55+) 0.001672 0.6%

All infants 0.003533 1.2%

Females (13-50) 0.001842 0.6%

Children (1-2) 0.006413 2.1%

Children (3-5) 0.005369 1.8%

Children (6-12) 0.003440 1.1%

Youth (13-19) 0.002043 0.7%

Adults (20-49) 0.001942 0.6%

Adults (50-99) 0.001687 0.6%

Females (13-49) 0.001848 0.6%

The %RfD values ranged from 0.6% to 2.1%; the highest %RfD being for children aged 1-2 

years. These values are all significantly below 100 and therefore do not exceed the Agency’s 

LOC. These results indicate that the dietary risk for humans from pesticidal exposure to tea tree 

oil is expected to be negligible.

Assessment # 2: DEEM-FCID using surrogate information (ultra-conservative approach)

To further support the finding that dietary risk to humans from pesticidal exposure to tea tree oil 

is expected to be negligible and subsequently justify the exemption from the requirement of a 

tolerance for tea tree oil on certain food commodities, the Agency conducted an extremely 

conservative estimate of dietary risk. In the absence of specific residue data, the Agency has 

developed an approach which uses surrogate information to derive upper bound exposure 

estimates for an ingredient in a pesticide product. The exposure estimates are based on the 

highest tolerance for a given commodity from a list of high-use conventional insecticides, 

herbicides, and fungicides. A complete description of the general approach taken to assess 

ingredient risks in the absence of residue data is contained in the memorandum entitled “Alkyl 

Amines Polyalkoxylates (Cluster 4): Acute and Chronic Aggregate (Food and Drinking Water) 

Dietary Exposure and Risk Assessments for the Inerts.” (D361707, S. Piper, 2/25/09), and can be 

found at http://www.regulations.gov in docket ID number EPA-HQ-OPP-2008-0738. The 

document pertains to the dietary risk assessment of an inert ingredient, but the methodology is 

being employed by BPPD for use in the dietary risk assessment for a biopesticide active 

ingredient.
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In its assessment, The Agency assumed that the residue level of tea tree oil (specifically, 

terpinen-4-ol) would be no higher than the highest tolerance for a given commodity. Implicit in 

this assumption is that there would be similar rates of degradation (if any) between the 

conventional and biopesticide active ingredients and that the concentration of the biopesticide in 

the scenarios leading to these highest of tolerances would be no higher than the concentration of 

the conventional active ingredient. The Agency believes that the assumptions used to estimate 

dietary exposures lead to an extremely conservative estimate of dietary risk due to a series of 

compounded conservatisms: 1) the assumption that the residue level of the biopesticide is equal 

to the level of residue for the conventional pesticide will significantly overstate exposure. The 

constituents of tea tree oil are expected to degrade rapidly in the environment and it is highly 

unlikely that residue levels of tea tree oil would be similar to those of the conventional active 

ingredients, which the tolerances used in the dietary assessment are based upon; 2) the 

assumption that for each commodity, the conventional active ingredient that will serve as a guide 

to the potential level of biopesticide residues is the conventional active ingredient with the 

highest tolerance level. The assumption overstates residue values because it would be highly 

unlikely that a biopesticide, specifically, tea tree oil, would be present at the level of the 

conventional active ingredient in the highest tolerance for every commodity for which an 

exemption is requested; and 3) the assumption that all foods contain the biopesticide at the 

highest tolerance level. In other words, the Agency assumes that 100 percent of commodities are 

treated with the biopesticide at the rate and manner necessary to produce the highest residue 

legally possible for a conventional active ingredient. In summary, the Agency chose a very 

conservative method for estimating what level of the biopesticide residue could be in or on food 

and then used the methodology to choose the highest possible residue that could be found on 

food and assumed that all food contained this residue. No consideration was given to the 

potential degradation between harvest and consumption even though monitoring data shows that 

tolerance level residues are typically one to two orders of magnitude higher than actual residues 

in food when distributed in commerce. Accordingly, although sufficient information to quantify 

actual residue levels of a biopesticide, e.g.: tea tree oil, is not available, the compounding of the 

conservative assumption will lead to a significant exaggeration of actual exposures. The Agency 

does not believe that this approach underestimates exposure in the absence of residue data.

The results of the DEEM-FCID analysis and risk assessment are presented in Table 4 below.
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Table 4: DEEM-FCID Chronic Analysis for Tea Tree Oil (specifically terpinen-4-ol)-Ultra-Conservative

Population Subgroups

(age in years)

Estimated Dietary Exposure 

(mg/kg bw/day) Percent RfD

U.S. Population 0.095133 31.7%

Hispanics 0.090487 30.2%

Non-hispanics whites 0.099301 33.1%

Non-hispanic blacks 0.072545 24.2%

Non-hispanic/Non-white/Non-black 0.105237 35.1%

Nursing infants 0.074365 24.8%

Non-nursing infants 0.128558 42.9%

Females (13+) pregnant 0.082419 27.5%

Children (1-6) 0.208179 69.4%

Children (7-12) 0.102048 34.0%

Male 13-19 0.065080 21.7%

Females (13-19) not pregnant 0.070148 23.4%

Male (20+) 0.079670 26.6%

Females (20+) not pregnant 0.089827 29.9%

Seniors (55+) 0.087060 29.0%

All infants 0.111827 37.3%

Females (13-50) 0.084436 28.1%

Children (1-2) 0.249669 83.2%

Children (3-5) 0.193070 64.4%

Children (6-12) 0.111120 37.0%

Youth (13-19) 0.067516 22.5%

Adults (20-49) 0.083857 28.0%

Adults (50-99) 0.086492 28.8%

Females (13-49) 0.084518 28.2%

The %RfD values ranged from 21.7% to 83.2%; the highest %RfD being for children aged 1-2

years. These values are all below 100 and therefore do not exceed the Agency’s LOC. These 

results indicate that even under extremely conservative dietary exposure scenarios, the dietary 

risk for the U.S. population in general, including sensitive subpopulations, is expected to be 

negligible.

 b. Drinking Water Exposure and Risk Characterization

Residues of the constituents of tea tree oil in drinking water are not expected when the product is

used according to label instructions. The constituents of the active ingredient are mostly volatile 

compounds that are already present in the environment in plants and water. They are expected to 

volatilize and degrade rapidly in the environment and are not directly applied to water; therefore, 

residues of tea tree oil in drinking water are unlikely.

c. Acute and Chronic Dietary Risks for Sensitive Subpopulations Particularly 

Infants and Children

The Agency has determined that there are no foreseeable dietary risks to sensitive 

subpopulations, including infants and children, from the use of tea tree oil in the proposed 

product when label instructions are followed. This conclusion is based on the following: 1) 

significant dietary exposure is not anticipated when label instructions for the proposed product 

are followed, 2) dietary risk to infants and children is anticipated to be negligible based on the 

results of the dietary risk assessments that the Agency has conducted (see Section IV.B.3.a
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above) and 3) humans are already exposed to tea tree oil in cosmetic and personal care products,

and its major constituents are found naturally in the diet, in the environment, and are used as 

food additives. 

4. Occupational, Residential, School and Day Care Exposure and Risk Characterization

a. Occupational Exposure and Risk Characterization

Dermal exposure to mixers/loaders and applicators is not anticipated as adequate PPE 

requirements are on the proposed EP label. Additionally, the active ingredient degrades rapidly 

in the environment which further mitigates dermal exposure. Due to the potential for inhalation 

exposure of residues of tea tree oil to mixers/loaders and applicators (the EP is applied as a 

spray, fog or drench), and the effects observed in the 90-day oral toxicity and prenatal 

developmental studies, an occupational exposure and risk assessment was conducted. The results 

of the risk assessment indicate that risk from inhalation exposure to tea tree oil is negligible for 

mixers/loaders and applicators when the pesticide product (Timorex Gold [EPA File Symbol No. 

86182-R]) is used according to label instructions. A summary of the assessment is provided 

below.

The assessment was conducted using a POD of 30 mg/kg bw/day (the NOAEL from the 90-day 

oral and developmental toxicity studies) and the occupational handler exposure calculation 

spreadsheet developed by OPP’s Health Effects Division (HED). Because 90-day inhalation 

toxicity data are not available, the Agency has bridged the data from the 90-day oral toxicity 

study and assumed 100% absorption via inhalation. The standard body weight for females (69 

kg) was used for all exposure scenarios in the assessment due to the incidence of developmental 

effects. Based on label instructions, exposure scenarios consisted of the following application 

methods: ground boom, airblast, aerial, and mechanically-pressured handgun. The application 

rate used for the exposure assessment was the maximum application rate on the label (1.6 lb 

a.i./acre). Potential daily exposures for occupational handlers (mixer/loaders and applicators)

were calculated in the spreadsheet using the following formulas:

Daily exposure to the pesticide: 

Daily Exposure (mg ai /day) = UE (μg ai / lb ai) * AR (lb ai /A) * AT (A /day) * 1E-3 mg/μg

Daily Exposure = amount of the active ingredient that is available for inhalation absorption,

UE = Unit Exposure (generic values derived using measurements of exposure data in the field)

AR = maximum application rate according to proposed label

AT = daily acres treated.

The average daily dose (daily exposure adjusted for absorption and body weight) was calculated 

using the following formula:

Average Daily Dose (mg ai/kg/day) = [Daily Exposure (mg ai/day) * Absorption (%)]

Body Weight (kg)
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Average Daily Dose (ADD) = absorbed dose received from exposure to the active ingredient in a 

given scenario

Daily Exposure = amount of the active ingredient that is available for inhalation absorption

Absorption Factor = a measure of the amount of chemical that crosses a biological boundary 

such as the skin and lungs (%)

Body Weight = body weight determined to represent the population of interest in a risk 

assessment

Risk for each application handler scenario was calculated using a MOE, which is a ratio of the 

toxicological endpoint to the daily dose of concern. The daily inhalation dose received by 

occupational handlers was compared to the POD (i.e.: NOAEL) to assess the risk to occupational 

handlers. All MOE values were calculated using the following formula:

MOE = POD (i.e.: NOAEL in mg/kg/day) 

ADD (mg/kg/day)

All MOEs calculated for mixers/loaders and applicators using no inhalation PPE were 

significantly greater than the Agency’s LOC of 100 (10X for intraspecies variation and 10x for 

interspecies variation). MOEs greater than 100 do not exceed the Agency’s LOC; therefore, risks 

are not considered to be of concern. Based on the results of the occupational risk assessment, 

unreasonable adverse effects to handlers are not anticipated when the pesticide product is used 

according to label instructions. A summary of the exposure scenarios and MOEs is provided in 

Table 5 below.

 

Significant post-application exposure to tea tree oil is not anticipated as there is a 4-hour REI on 

the EP label and the active ingredient is expected to rapidly degrade in the environment.

b. Residential, School and Day Care Exposure and Risk Characterization

Significant exposure to tea tree oil is not anticipated in residential, school, and day care areas, as 

TABLE 5. Occupational Risk Assessment Summaries for Tea Tree Oil (Inhalation Route of Exposure)

Worker Activity Application Equipment/Application Type Application Type MOE

Mixer/Loader Aerial/Broadcast Orchard 17,000

Mixer/Loader Aerial/Broadcast Field crop, typical 17,000

Mixer/Loader Aerial/Broadcast Field crop, high-acreage 4,900

Mixer/Loader Airblast/Broadcast Orchard 150,000

Mixer/Loader Groundboom/Broadcast Field crop, typical 74,000

Mixer/Loader Groundboom/Broadcast Field crop, high-acreage 29,000

Applicator Aerial/Broadcast Orchard Exposure not anticipated

Applicator Aerial/Broadcast Field crop, typical Exposure not anticipated

Applicator Aerial/Broadcast Field crop, high-acreage Exposure not anticipated

Applicator Airblast/Broadcast Orchard 6,900

Applicator Groundboom/Broadcast Field crop, typical 48,000

Applicator Groundboom/Broadcast Field crop, high-acreage 19,000

Flagger Aerial/Broadcast Orchard 11,000

Flagger Aerial/Broadcast Field crop, typical 11,000

Flagger Aerial/Broadcast Field crop, high-acreage 11,000
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the product containing this active ingredient is intended for use on horticultural and agricultural 

crops.

5. Aggregate Exposure from Multiple Routes Including Dermal, Oral, and Inhalation

The Food Quality Protection Act amendments to the Federal Food, Drug, and Cosmetic Act 

(FFDCA, Section 408(b)(2)(A)(ii)) require “that there is a reasonable certainty that no harm will 

result from aggregate exposure to pesticide chemical residue, including all anticipated dietary 

exposures and other exposures for which there are reliable information.” Aggregate exposure 

will typically include exposures from food, drinking water, residential uses of a pesticide, and 

other non-occupational sources of exposure.

For tea tree oil, qualitative aggregate exposure and risk assessments were conducted. For the 

pesticidal uses, dietary exposures were evaluated. Residential exposures are not anticipated 

based on the use pattern of tea tree oil. Drinking water exposure is not anticipated based on the 

rapid degradation of the active ingredient in the environment. Additionally, tea tree oil is not 

directly applied to water. For the aggregate assessment, the routes of exposure evaluated were 

oral (via dietary exposure). Significant dermal and inhalation exposures are not anticipated based 

on the use pattern of the pesticide; tea tree oil is for agricultural use only. 

The active ingredient is not currently used and is not proposed for use as an inert ingredient in 

pesticide products. Based on the known current uses of tea tree oil in the cosmetic and 

pharmaceutical industries, the general population is likely to be exposed to tea tree oil. 

Exposures to tea tree oil in these products are likely to be at lower concentrations because tea 

tree oil is corrosive to the skin and eyes at higher concentrations according to the data available 

to the Agency. As stated earlier in this document, the general population is also exposed to the 

major constituents of tea tree oil in the diet, as they are found naturally in foods and are 

intentionally added to foods as food additives. Reliable data on exposures to tea tree oil via food, 

cosmetic and pharmaceutical uses are not available; thus, a quantitative aggregate exposure and 

risk assessment was not conducted. Instead, EPA conducted a qualitative aggregate exposure and 

risk assessment. Dietary exposure from use as a pesticide is anticipated to be minimal based on 

the anticipated rapid degradation of the active ingredient in the environment. The constituents of 

tea tree oil are volatile and degrade quickly once the pesticide is applied. As part of the 

qualitative aggregate exposure and risk assessment, the Agency used the dietary risk assessment 

that was conducted for tea tree oil (refer to Section IV.3.B.a). The highest dietary exposure 

estimated in the assessment was 0.006 mg/kg/day. The calculated risk was 2.1% of the reference 

dose (RfD). Generally, risks from exposures that are less than 100% of the RfD are not a risk 

concern.

The Agency believes that the dietary risk assessment is very conservative and protective of any 

additional exposures to tea tree oil via foods, cosmetics, and pharmaceuticals because the 

potential pesticide-exposed population utilizes only approximately 2% of the RfD, leaving 98% 

of the RfD for exposure from non-pesticidal uses (e.g.: foods, cosmetics, and pharmaceuticals).

Based on the Agency’s risk assessments, pesticidal exposure via the oral, dermal and inhalation 

routes is anticipated to be negligible and not expected to contribute significantly to the overall 

exposure of tea tree oil to the U.S. population.
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In consideration of the above information, the Agency has determined the risk from aggregate 

exposure (via oral, dermal, and inhalation exposures) is negligible; there is reasonable certainty 

that no harm will result to the general population or to infants and children from aggregate 

exposure to tea tree oil.

6. Cumulative Effects

EPA has considered the potential for cumulative effects of tea tree oil and other substances in 

relation to a common mechanism of toxicity. Unlike other pesticides for which EPA has 

followed a cumulative risk approach based on a common mechanism of toxicity, the Agency has 

not made a common mechanism of toxicity finding for tea tree oil and any other substances and 

tea tree oil does not appear to produce a toxic metabolite produced by other substances. The 

active ingredient is a biopesticide that has a nontoxic mode of action. For information regarding 

EPA’s efforts to determine which chemicals have a common mechanism of toxicity and to 

evaluate the cumulative effects of such chemicals, see the policy statements released by the 

Agency’s Office of Pesticide Programs concerning common mechanism determinations and 

procedures for cumulating effects from substances found to have a common mechanism on 

EPA’s website at http://www.epa.gov/pesticides/cumulative/.

7. Risk Characterization

The Agency has considered human exposure to tea tree oil in light of the relevant safety factors 

in FQPA and FIFRA. A determination has been made that no unreasonable adverse effects to the 

U.S. population in general, and to infants and children in particular, will result from the use of 

tea tree oil as a pesticide when label instructions are followed.

C. Environmental Assessment

1. Ecological Hazards

Adequate nontarget toxicology data/information is available to support registration of tea tree oil 

with the submission of nontarget toxicology data on the TGAI. All nontarget toxicology data 

requirements for tea tree oil have been satisfied.

Tea tree oil is highly toxic to aquatic invertebrates. Tea tree oil is practically nontoxic to fish and

insects. Tea tree oil is not phytotoxic. Significant exposure of tea tree oil to birds is not expected 

due to volatilization and rapid degradation of the active ingredient in the environment (EPA, 

2013).

For more information regarding nontarget organism toxicity data requirements, refer to Table 9

in Appendix A.

2. Environmental Fate and Ground Water Data 

Tea tree oil is expected to degrade rapidly in the environment. Up to 90% of tea tree oil has been 
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shown to volatilize within 24 hours after application and residue studies indicate the lack of 

detectable residues of three of the major constituents of tea tree oil at 48 hours post-application 

(EPA, 2013). In MRID 48275004, a study was submitted in which the biodegradation of tea tree 

oil was determined in a 28-day ready biodegradability assay (OECD Guideline 310 and EN ISO 

14593) by monitoring the release of carbon dioxide with a non-adapted activated sewage sludge. 

Based on the results of the assay, biodegradation of tea tree oil was 10% after 2 days, 60% after 

5 days, 87% by day 7, and 106% at study termination.

3. Ecological Exposure and Risk Characterization

Significant exposure to birds is not expected because the active ingredient is volatile and 

degrades rapidly in the environment. Additionally, birds are already exposed to the components 

of tea tree oil, as they are present in a multitude of plants. Although exposure to fish, insects, and 

plants is anticipated from use of the product through direct application, accidental application, 

drift or run-off, results of toxicity testing on pure tea tree oil indicate that tea tree oil is 

practically nontoxic to these organisms. The proposed EP which contains 23.8% tea tree oil will 

also be diluted with water prior to application, which will further reduce exposure to these 

organisms. The aquatic invertebrate toxicity study submitted indicates that tea tree oil is highly 

toxic to these organisms. Because of the potential for toxicity to freshwater invertebrates, risk 

assessments for these organisms will need to be conducted for products containing tea tree oil as 

an active ingredient. Since nontarget organism toxicology data on the proposed EP are available, 

a risk assessment was conducted for the EP (EPA, 2014). The results of the risk assessment for 

the EP indicated that mitigation language for aquatic invertebrates is required on the EP label. 

4. Endangered Species Assessment

The Agency has not conducted a risk assessment that supports a complete endangered species 

determination. The ecological risk assessment planned during registration review will allow the 

Agency to determine whether tea tree oil’s use has “no effect” or “may effect” federally listed 

threatened or endangered species (listed species) or their designated critical habitats. When an 

assessment concludes that a pesticide’s use “may affect” a listed species or its designated critical 

habitat, the Agency will consult with the U.S. Fish and Wildlife Service and/or National Marine 

Fisheries Services (the Services) as appropriate.

D. Efficacy Data

Product performance data must be developed for all pesticides to ensure that pesticide products

will perform as intended and that unnecessary pesticide exposure to the environment will not 

occur as a result of the use of ineffective products. The Agency reserves the right to require on a 

case-by-case basis, submission of efficacy data for any pesticide product registered or proposed 

for registration that are intended to be used to control a pest of significance public health 

importance and a public health pest as defined in FIFRA section 28(d) and section 2(nn). For 

further guidance on product performance requirement, refer to Pesticide Registration Notice (PR) 

Notices 96-7, 2002-1 and Explanation of Statutory Framework for Risk-Benefit Balancing for 

Public Health Pesticides (http://www.epa.gov/PR _Notices/pr1996-7.pdf) 

(http://www.ea.gov/PR_Notices/pr2002-1.pdf) and (http://www.epa.gov/pesticides/health/risk-
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benefit.htm).

The EP submitted with this new active ingredient did not list pests of significance public health 

importance or a public health pest as defined in FIFRA section 28(d) and section 2(nn). 

Therefore, product performance (efficacy) was not evaluated. 

V. RISK MANAGEMENT DECISION

A. Determination of Eligibility for Registration 

Section 3(c)(5) of FIFRA provides for the registration of a new active ingredient if it is 

determined that: (A) its composition warrants proposed claims; (B) its labeling and other 

materials comply with the requirements of FIFRA; (C) it will perform its intended function 

without unreasonable adverse effects on the environment; and (D) when used in accordance with 

widespread and commonly recognized practice, it will not generally cause unreasonable adverse 

effects on the environment. 

The four criteria of the Eligibility Determination for Pesticidal Active Ingredients are satisfied by 

the science assessments supporting products containing the TGAI, tea tree oil. Such products are 

not expected to cause unreasonable adverse effects. Therefore, tea tree oil as a TGAI is eligible 

for registration for the labeled uses. 

B. Regulatory Decision

The data submitted fulfill the registration requirements of tea tree oil for use as a 

fungicide/bactericide. Refer to Appendix B for product-specific information.

Conditional/Unconditional Registration

All data requirements are fulfilled, and EPA determined that an unconditional registration of tea 

tree oil is appropriate.

Consistent with the policy of making registration actions more transparent, tea tree oil is subject 

to a 15-day comment period as a “new active ingredient.” EPA has established a comment period 

of 15 days on the basis of tea tree oil minimal toxicity, the determination that tea tree oil presents 

low risk of any adverse effects to human health and the environment, and critical need for this 

active ingredient. The notice for this comment period includes the draft BRAD and draft product 

labels for the MP, Tea Tree Oil Technical, and EP, Timorex Gold, which contain this new active 

ingredient, tea tree oil. The docket identification (ID) number is EPA-HQ-OPP-2009-0440. The 

Agency believes that based on the risk assessment and information submitted in support of the 

registration of the MP and EP containing tea tree oil, it is in the best interests of the public to 

issue the registration for Tea Tree Oil Technical and Timorex Gold. The basis for this decision 

can be found in the risk assessment for tea tree oil, which is characterized in this BRAD. 
Tea Tree Oil

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C. Environmental Justice

EPA seeks to achieve environmental justice—the fair treatment and meaningful involvement of 

all people regardless of race, color, national origin, or income—with respect to the development, 

implementation, and enforcement of environmental laws, regulations, and policies. At this time, 

EPA does not believe that use of tea tree oil pesticide products will cause harm or a 

disproportionate impact on at-risk communities. For additional information regarding 

environmental justice issues, please visit EPA’s website at

http://www.epa.gov/compliance/environmentaljustice/index.html.

VI. ACTIONS REQUIRED BY REGISTRANTS

EPA evaluated all data submitted in connection with the registration of the tea tree oil pesticide 

products and determined that these data are sufficient to satisfy current registration data 

requirements. At this time, no additional data must be submitted to EPA for these particular 

products. For new uses and/or changes to existing uses, EPA may require additional data. 

Notwithstanding the information stated in the previous paragraph, it should be clearly understood 

that certain specific data are required to be reported to EPA as a requirement for maintaining the 

Federal registration for a pesticide product. A brief summary of these types of data are listed 

below. 

A. Reporting of Adverse Effects

Pursuant to FIFRA section 6(a)(2), reports of all incidents of adverse effects to the environment 

must be submitted to EPA.

B. Reporting of Hypersensitivity Incidents

Additionally, all incidents of hypersensitivity (including both suspected and confirmed incidents) 

must be reported to the Agency under the provisions of 40 CFR Part 158.2050(d).

VII. APPENDIX A. DATA REQUIREMENTS (40 CFR PART 158-SUBPART U)

*NOTE: Master Record Identification (MRID) numbers listed in the following tables are 

representative of supporting data/information for the original registration of the product 

containing this active ingredient. Subsequent to this registration, there may be additional MRIDs 

that support registration of other products containing this active ingredient. 
Tea Tree Oil

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TABLE 6. Product Chemistry Data Requirements for Tea Tree Oil (40 CFR § 158.2030)

OCSPP Guideline Reference No./Study Description of Result MRID

880.1100 Product identity and composition The product identity and composition were 

adequately addressed. Confidential Business 

Information (CBI).

47730401

880.1200 Description of starting materials, 

production, and formulation 

process

The description of the starting materials, 

production, and formulation process were 

adequately addressed. CBI.

47730401

880.1400 Discussion of formation of 

impurities

The discussion of formation of impurities was 

adequately addressed. CBI. 47730401

830.1700 Preliminary analysis The preliminary analysis of the product was 

acceptable. CBI. 47730402, 47730403

830.1750 Certified limits The certified limits listed on the CSF are 

acceptable. 47730401

830.1800 Enforcement analytical method The enforcement analytical method was 

adequately addressed. CBI. 47730401
Tea Tree Oil

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TABLE 7. Physical and Chemical Properties for Tea Tree Oil (40 CFR § 158.2030)

OCSPP Guideline Reference No./Property Description of Result MRID

830.6302 Color Colorless to pale yellow 47730401

830.6303 Physical State Liquid 47730401

830.6304 Odor Characteristic 47730401

830.6313 Stability to normal and elevated 

temperatures, metals and metal 

ions

Decomposition temperature is expected to be 

>200°C (based on values for the individual 

components).

Generally stable to galvanized steel 

(packaging material) over 8 months at 

ambient warehouse storage, 10-35 ̊C.

47730401

Correspondence 

between Canada’s Pest 

Management 

Regulatory Agency 

(PMRA) and TSG 

dated May 11, 2009 

and PMRA product 

chemistry review.

830.6315 Flammability Flashpoint = 55°C

 59°C

47918402

47730401

830.6317 Storage Stability Composition of TGAI may vary considerably 

during storage, with ρ-cymene levels 

increasing and α- and γ-terpinene levels 

decreasing. Light, heat, air exposure and 

moisture affect oil stability. The MP should be 

stored in dark, cool, dry conditions in an 

airtight container.

During the 8 month study, of the 5 major 

components, α-terpinene decreased ~13% and 

ρ-cymene increased ~15.5%, with the other 

three not changing significantly.

Correspondence 

between PMRA and 

TSG dated May 11, 

2009, and PMRA 

product chemistry 

review.

830.6319 Miscibility Not applicable, the product is not to be mixed 

with petroleum solvents.

47730401

830.6320 Corrosion Characteristics Generally stable to galvanized steel 

(packaging material) over 8 months at 

ambient warehouse storage, 10-35 ̊C. No 

visual changes (corrosion, color change) were 

observed. 

Correspondence 

between PMRA and 

TSG dated May 11, 

2009, and PMRA 

product chemistry 

review.

830.7000 pH Not applicable 47730401

830.7050 UV/Visible light absorption In propan-2-ol, a single maximum at 265 nm 

was observed.

47730409 and 

47918403

830.7100 Viscosity 2.47 cSt at 25oC 48275001

830.7200 Melting Range Not applicable, the product is a liquid. 47730401

830.7220 Boiling Range Expected to be ca. 200°C (derived from 

values of the individual components)

47730401

830.7300 Density/Relative Density/Bulk 

Density

Minimum density = 0.885 g/mL at 20°C

Maximum density = 0.906 g/mL at 20°C

47730401

830.7520 Particle size, fiber length, and 

diameter distribution

Not known for TGAI. Relevant components 

of TGAI are not expected to dissociate. 

47730401 and 

47730409
Tea Tree Oil

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Biopesticides Registration Action Document

TABLE 7. Physical and Chemical Properties for Tea Tree Oil (40 CFR § 158.2030)

OCSPP Guideline Reference No./Property Description of Result MRID

830.7550 Partition Coefficient (n-Octanol/ 

830.7560 Water)

830.7570

Not known for TGAI.

Component log Kow

terpinen-4-ol 2.643 

3.33 

γ-terpinene 4.47 

α-terpinene 4.75 

p-cymene 4.44 

1,8-cineole 3.13 

47730401 and 

47730409

830.7840 Water Solubility Not known for TGAI. 

Component Temp ( ̊C) Solubility

terpinen-4-ol - 1767 mg/L 

γ -terpinene 22-25 8.72 mg/L 

α-terpinene - 5.92 mg/L 

p-cymene - 5.0 mg/L 

1,8-cineole - 552 mg/L

47730401 and 

47730409

830.7950 Vapor Pressure Not known for TGAI. 

Component Temp ( ̊C) VP (Pa)

terpinen-4-ol 20 53.2 

-terpinene 20 93.1 

23.5 103 

α-terpinene 20 106.4

p-cymene 25 199.5 

1,8-cineole 25 253 

47730401 and 

47730409
Tea Tree Oil

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Biopesticides Registration Action Document

Table 8: Mammalian Toxicology Data Requirements for Tea Tree Oil (40 CFR § 158.2050)

Study/OCSPP Guideline No. Results Toxicity 

Category/Description MRID

Acute oral toxicity (rat)

(870.1100)

LD50 = 1752 mg/kg (1752-2450 mg/kg) Toxicity Category III 47730404

Acute dermal toxicity (rat)

(870.1200)

LD50 > 2000 mg/kg Toxicity Category III 47730404

Acute inhalation toxicity (rat)

(870.1300)

LC50 = 3.64 mg/L Toxicity Category IV 48598701

48878201

Primary eye irritation (rabbit)

(870.2400)

Waived: MP is corrosive to skin.

A chorioallantioic membrane vascular assay 

(chicken egg) was submitted, but is 

unacceptable as EPA has not established this 

assay to be appropriate to fulfill the primary 

eye irritation data requirement. 

Toxicity Category I

47730405

Primary dermal irritation (rabbit)

(870.2500)

Corrosive. Well-defined to severe erythema 

and barely perceptible to slight edema were 

noted on the intact sites of 6/6 rabbits at the 

24- and 72-hour evaluations. Well-defined 

to severe erythema and barely perceptible to 

moderate edema were noted on the abraded 

sites of 6/6 rabbits at the 24 and 72 hour 

evaluations. Three animals had erosion on 

abraded sites at the 72-hour evaluation. The 

primary irritation index (PII) was 5.0.

Toxicity Category I

47730404

Dermal sensitization (guinea pig)

(870.2600)

Waived: MP is corrosive to skin.

A skin sensitization study was submitted. 

After intradermal and epidermal inductions, 

the test and control animals showed no signs 

of reactivity 24 hours after challenge. 

However, study classification is 

unacceptable due to the lack of positive 

control data. 

-

47730404

90-Day oral toxicity

(870.3100)

LOAEL = 60 mg/kg/day based on testicular 

toxicity in males and increased liver to body 

weight ratios in females

NOAEL = 30 mg/kg/day for males and 

females

-

48598702

48878202

90-Day dermal toxicity

(870.3250)

Waived: prolonged dermal exposure not 

anticipated. TGAI is corrosive to skin and 

adequate PPE is required on the label.

Undiluted tea tree oil caused severe 

irritation to the skin on the first day of a

non-guideline 30-day dermal irritation study 

on rabbits. For the remainder of the study, a 

25% solution in paraffin oil was applied to 

the skin which did not result in visible 

irritation; however, non-specific 

microscopic dermatitis consistent with 

irritation was observed. 

-

47730411

47730404

90-Day inhalation toxicity

(870.3465)

The data from the 90-data oral toxicity study 

has been bridged to satisfy this data 

requirement. A route to route extrapolation 

will be employed using a 100% absorption 

assumption.

-

48598704

48878201
Tea Tree Oil

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Biopesticides Registration Action Document

Table 8: Mammalian Toxicology Data Requirements for Tea Tree Oil (40 CFR § 158.2050)

Study/OCSPP Guideline No. Results Toxicity 

Category/Description MRID

Developmental toxicity

(870.3700)

Maternal:

NOAEL = 30 mg/kg/day 

LOAEL = 60 mg/kg/day based on treatment 

related decreased body weight gain and food 

intake

Developmental:

NOAEL = 60 mg/kg/day

LOAEL = 120 mg/kg/day based on 

decreased fetal weights

- 49166401

Mutagenicity – Tier I

(870.5100, 5300 and 5375)

Mutagenicity – Tier II

(870.5395)

Not mutagenic in Salmonella reverse 

mutation assay at doses below 50 μg.

Negative in in vivo mouse bone marrow 

micronucleus assay.

-

47730404

47730407

47730409

Table 9: Nontarget Organism Toxicity Data Requirements for Tea Tree Oil (40 CFR § 158.2060)

Study/OCSPP Guideline No. Results Toxicity 

Category/Description MRID

Avian acute oral toxicity

(850.2100)

Adequate information to support data 

requirement: significant exposure to birds is 

not expected due to volatilization and rapid 

degradation of the active ingredient in the 

environment. Additionally, components of 

the TGAI are already found in a multitude of 

plants. 

Significant exposure 

not expected

47730411

Avian dietary toxicity

(850.2200)

Adequate information to support data 

requirement: significant exposure to birds is 

not expected due to volatilization and rapid 

degradation of the active ingredient in the 

environment. Additionally, components of 

the TGAI are already found in a multitude of 

plants. 

Significant exposure 

not expected

47730411

Aquatic invertebrate acute 

toxicity, freshwater

(850.1010)

48-hour EC50 = 0.591 mg/L 

(95% CL: 0.499-0.700 mg/L) Highly toxic 48598703

Fish acute toxicity, freshwater

(850.1075)

LC50 > 100 mg/L Practically non-toxic

47730408

Terrestrial plant toxicity, Seedling 

emergence/Vegetative vigor 

(850.4100 and 850.4150)

Adequate information to support data 

requirement: using the proposed EP in 

efficacy trials on squash, potatoes, apples, 

no phytotoxicity was observed. Minor 

phytotoxicity was observed in one South 

African grape variety (brown spots) in one 

trial; however, in nine other trials in grapes 

no phytotoxicity was observed. Minor 

phytotoxicity was observed in one trial in 

tomatoes and cucumbers (small necrotic 

spots); however, no phytoxicity was 

observed in eleven other trials in tomatoes. 

The components of tea tree oil are volatile 

and are also already found in a multitude of 

plants.

Not phytotoxic 47730521

Nontarget insect testing Apis millifera: oral LD50 > 98.5 μg a.i./bee; 477305201
Tea Tree Oil

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Biopesticides Registration Action Document

Table 9: Nontarget Organism Toxicity Data Requirements for Tea Tree Oil (40 CFR § 158.2060)

Study/OCSPP Guideline No. Results Toxicity 

Category/Description MRID

(880.4350) contact LD50 > 331 μg a.i./bee

Bombus terrestris: oral LD50 > 105.49 μg 

a.i./bee; contact LD50 > 100 μg a.i./bee

Aphidius rhopalosiphi: ER50 and LR50 

>1.08 L EP/ha 

Typhlodromus pyri: ER50 = 1.78 L EP/ha 

(95% c.i., 1.54-2.09 L EP/ha); 7d LR50 

>4.32 L EP/ha

Practically non-toxic 477305192

477305183

477305173

1Study conducted on the proposed EP, Timorex Gold (EPA File Symbol No. 86182-R), at target doses of 100 μg a.i./bee (oral) 

and 18, 32, 56, 100, 180, and 320 μg a.i./bee (contact)

2 Study conducted on the proposed EP, Timorex Gold (EPA File Symbol No. 86182-R), at a target dose of 100 μg a.i./bee 

(nominally equivalent to 423.73 μg EP/bee)

3 Supplemental data. Values reported are based on the proposed EP, Timorex Gold (EPA File Symbol No. 86182-R), and have 

not been corrected for active ingredient concentration.

VIII. APPENDIX B.

For product specific information, please refer to http://www.epa.gov/pesticides/pestlabels.

IX. APPENDIX C.

REFERENCES

EPA. 2010. Memorandum from Angela L. Gonzales to Colin Walsh. Joint Science Review with 

Health Canada Pest Management Regulatory Agency (PMRA) In Support of the Registration of 

Tea Tree Oil Technical containing Tea Tree Oil as its active ingredient. U.S. Environmental 

Protection Agency Office of Pesticide Programs. February 28, 2010.

EPA. 2013. Memorandum from Angela L. Gonzales thru Felecia A. Fort to Colin Walsh. Joint 

Science Review with Health Canada Pest Management Regulatory Agency In Support of the 

Registration of Tea Tree Oil Technical Containing Tea Tree Oil as its Active Ingredient. U.S. 

Environmental Protection Agency Office of Pesticide Programs. January 30, 2013.

EPA. 2014. Memorandum from Angela L. Gonzales to Colin Walsh. Science Review In Support 

of the Registration of Tea Tree Oil Technical Containing Tea Tree Oil as its Active Ingredient. 

U.S. Environmental Protection Agency Office of Pesticide Programs. April 10, 2014.

Henley DV, Lipson N, Korach KS, Block CA. 2007. Prepubertal gynecomastia linked to 

lavender and tea tree oils. N Engl J Med.; 356(5): 479-85

REVIEWS AND OTHER REFERENCES

EPA. 2010. Memorandum from Angela L. Gonzales to Colin Walsh. Joint Science Review with 
Tea Tree Oil

Page 33 of 34

Biopesticides Registration Action Document

Health Canada Pest Management Regulatory Agency (PMRA) In Support of the Registration of 

Timorex Gold containing Tea Tree Oil as its active ingredient. U.S. Environmental Protection 

Agency Office of Pesticide Programs. February 28, 2010.

EPA. 2013. Memorandum from Angela L. Gonzales to Colin Walsh. Joint Science Review with 

Health Canada Pest Management Regulatory Agency (PMRA) In Support of the Registration of 

Timorex Gold containing Tea Tree Oil as its active ingredient. U.S. Environmental Protection 

Agency Office of Pesticide Programs. January 30, 2013.

EPA. 2014. Memorandum from Angela L. Gonzales to Colin Walsh. Science Review in Support 

of the Registration of Timorex Gold containing Tea Tree Oil as its Active Ingredient. U.S. 

Environmental Protection Agency Office of Pesticide Programs. April 10, 2014.

X. GLOSSARY OF ACRONYMS AND ABBREVIATIONS

a.i. active ingredient

ARS Agricultural Research Service (USDA)

Biomor Biomor Israel, Ltd.

BPPD Biopesticides and Pollution Prevention Division

BRAD Biopesticide Registration Action Document

bw body weight

CBI Confidential Business Information

CFR Code of Federal Regulations

cm3cubic centimeter

CSF Confidential Statement of Formula

cSt centistokes

°C degrees Celsius

DEEM-FCID Dietary Exposure Evaluation Model - Food Commodity Intake Database

EC50 median effective concentration. A statistically derived single concentration in 

environmental medium that can be expected to cause an effect in 50% of the test 

animals when administrated by the route indicated (inhalation). It is expressed 

as a concentration in air or water (e.g. mg/L).

EDSP Endocrine Disruptor Screening Program

EDSTAC Endocrine Disruptor Screening and Testing Advisory Committee

EP end-use product

EPA Environmental Protection Agency (the “Agency”)

FDA U.S. Food and Drug Administration

FFDCA Federal Food, Drug, and Cosmetic Act

FIFRA Federal Insecticide, Fungicide, and Rodenticide Act

FQPA Food Quality Protection Act

FR Federal Register

g gram

ha hectare

kg kilogram

Kow octanol-water partition coefficient

L liter
Tea Tree Oil

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Biopesticides Registration Action Document

LC50 median lethal concentration. A statistically derived single concentration in air or 

water that can be expected to cause death in 50% of the test animals when 

administrated by the route indicated (inhalation and environment). It is 

expressed as a concentration in air or water (e.g. mg/L).

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 and dermal). It is expressed as a weight of 

substance per unit weight of animal (e.g., mg/kg).

LOAEL lowest-observed-adverse-effect-level

LOC level of concern

MOE margin of exposure

MRID No. Master Record Identification Number

mg milligram

mPa millipascal

mL milliliter

MP manufacturing-use product

N/A not applicable

NE “No Effect”

nm nanometer

NOAEL no-observed-adverse-effect-level

NOEL no-observed-effect-level

NOF notice of filing

NOR notice of receipt

OPP Office of Pesticide Programs

OCSPP Office of Chemical Safety and Pollution Prevention

pa pascal

PMRA Canada’s Pesticide Management Regulatory Authority

POD point of departure

PPE personal protective equipment

PR Notice Pesticide Registration Notice

REI restricted-entry interval

RfD reference dose

 TGAI technical grade of the active ingredient

 TSG Technology Sciences Group, Inc.

 UF uncertainty factor

 ug microgram

 USDA United States Department of Agriculture

 UV ultra-violet