UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

 WASHINGTON, D.C. 20460 

 

 OFFICE PREVENTION, 

 PESTICIDES AND TOXIC SUBSTANCES 

MEMORANDUM October 20, 2009

SUBJECT: Summary of Ecotoxicity Data for wood oils (040505: Cedarwood Oil; 

129035: Cinnamon) for the Registration Review Decision Document. 

EPA Reg No.: 040505, 129035, 120011, 129066 

Registration Review 

CAS No.: 8000-27-9, 8021-28-1, 35237-64-0, 

 

FROM: Miachel Rexrode, Ph.D., Senior Biologist /s/ 10/20/2009 

Biochemical Pesticides Branch 

Biopesticide & Pollution Prevention Division (7511P) 

TO: Sadaf Shaukat, Regulatory Action Leader /s/ 10/20/2009 

Biochemical Pesticides Branch 

Biopesticide & Pollution Prevention Division (7511P) 

ACTION REQUESTED 

The following is the final ecotoxicity assessment for wood oils (040505: Cedarwood Oil; 

129035: Cinnamon) in support of the Registration Review Decision Document. 

RECOMMENDATIONS AND CONCLUSIONS 

Executive Summary

Based on the available information for Cinnamon Oils and Cedarwood Oil, the Agency 

does not foresee the need for additional ecotoxicity data for a new risk assessment and 

has waived all hazard and exposure data on these chemicals. The unique characteristics of 

these products, their non-toxic mode of action, biodegradability (low to no persistence), 

and use patterns (non agricultural use, indoor uses) should minimize the risks to all nontargets, including threatened and endangered species. Cinnamon oil is a minimum risk 
pesticide that is exempt from federal registration under section 25(b) of the Federal 

Insecticide, Fungicide, and Rodenticide Act (FIFRA)1

. Cedarwood oil risk in the 

environment should be low, as noted from calculated RQ values that were about two 

orders of magnitude below the Agency’s LOCs suggesting minimal risk to terrestrial and 

aquatic organisms and a no effect (NE) to endangered/threatened species for registered 

uses. 

Background 

Cinnamon oil is a minimum risk pesticide that is exempt from federal registration under 

section 25(b) of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)1

. 

Cedarwood oil is among those pesticides for which EPA believes a broadly reduced set 

of generic data requirements is appropriate for reregistration. The Agency therefore has 

waived most generic data requirements for cedarwood oil with the exception of studies 

that are considered essential, including additional information about chemical purity 

and product chemistry studies. In evaluating cedarwood oil's potential risks to the 

environment, EPA relied on information commonly available in scientific literature. 

Cedarwood oil is a mixture of organic compounds. It is considered Generally Recognized 

as Safe (GRAS) as a food additive by the Food and Drug Administration. As a pesticide, 

it repels insects by a non-toxic mode of action. EPA is not aware of any adverse effects 

caused by cedarwood oil pesticide products when used in a manner prescribed by their 

labeling. No incidents involving toxic effects have been reported to the Agency. A 

laboratory study using mice and a study of workers in saw mills suggest that cedarwood 

oil may cause liver and pulmonary toxicity. However, these effects were associated with 

long term exposures to relatively high levels of cedarwood oil. 

Cedarwood oil is a natural component of wood from the tree, Juniperus virginiana L.. It 

is an active ingredient in five pesticide products that are used as repellents and feeding 

depressants to control moths and fleas and retard the growth of mildew. Three of these 

products are solid cedarwood blocks used to repel moths from clothing and retard mildew 

growth on fabrics. The other two products, which contain extracted cedarwood oil, are a 

pet tag or collar and a liquid sprayed on animal bedding. Both are intended to repel fleas 

from household pets. Cedar also is a major component of many non-pesticidal consumer 

products currently marketed in the United States. 

Although registration as a pesticide is no longer required by EPA for cedarwood oil, 

several formulations have been registered as pesticides in the past. These formulations 

include: ready-to-use liquids containing 0.48% cedarwood oil, wood blocks containing 2-

8% cedarwood oil, and pet collars with 0.5% cedarwood oil (EPA, 1993). Two pesticides, 

Bug Block sunscreen and insect repellent, containing 0.46% Texas cedarwood oil, and 

Nexa cedarwood oil moth protection, containing 40% Virginia cedarwood oil, are 

registered with the state of California as pesticides (California EPA, 2001)2

. 

EPA issued its Reregistration Eligibility Decision (RED) document for Cedarwood Oil in 

1993. The RED profiles the use of cedarwood oil as a natural repellant/feeding depressant 
and fungicide used in houses and on pets or their bedding to repel fleas, moths, and 

mildew. Based on information collected as the result of the RED, EPA deregulated 

cedarwood oil in 1996 and no longer requires manufacturers of cedarwood oil products to 

register them as pesticides (EPA, 1993)3

. The Agency does not foresee the need for 

additional ecotoxicity data for a new risk assessment. Ecological effects data 

requirements were fulfilled by waivers due to low toxicity and use/exposure patterns. 

Ecological Effects and Endangered Species Risk Assessment 

Terrestrial Species 

The unique characteristics of this product, wood oils, the non-toxic mode of action, 

biodegradability and low potential for exposure will result in no risk to all non-target 

organisms, including threatened and endangered species. Due to the non-toxic mode of 

action and/or lack of exposure to non-targets by this product, a Risk Quotient (RQ) is not 

typically calculated since the point estimates of either toxicity and/or exposure will be at 

or near zero. However, the Agency has estimated potential acute toxicity end points for 

avian and mammalian species (LD50 > 5,000 mg/kg) and calculated risk quotients (RQs) 

using the Terrestrial Residue Exposure Model (T-REX) Version 1.4.1. A terrestrial risk 

assessment includes calculated expected residues, as well as, numerous calculations of 

dietary exposure for multiple weight class animals (Appendix A). Although cedarwood 

oil is not used on agricultural crops, expected residues were calculated for avian and 

mammalian food items along with dissipation rate of a chemical applied to foliar surfaces 

(single or multiple applications) in order to estimate worst case acute RQs relative to 

weight class for various sized birds and mammals. These calculations showed upper 

bound Kenega values and that exposure to cedarwood oil (0.01 lbs ai) has a low potential 

for toxic impact to birds (RQ = 0.0) and mammals (RQ= 0.00) that may be feeding in the 

area of application as noted in Appendix A. The low toxic risk of cedarwood oil to 

terrestrial organisms, the short environmental half life (0.125 days) and an understanding 

of the repellent mode of action of this compound show that there is a very low potential 

for toxic risk to birds and mammalian species. In addition to this low risk to non-target 

terrestrial species, the potential for exposure to endangered/threatened species is also very 

low because the formulated products are used indoors and/or in enclosed areas outdoors. 

The Agency acute levels of concern (0.1 – 0.5) were not exceeded for terrestrial 

organisms or for endangered/threatened species. Based on this information on the active 

ingredients, there will not be toxic risk to endangered/ threatened species from exposure 

to the end use products. Cedarwood oils present a No Effect (NE) to threatened or 

endangered terrestrial species, if used in accordance with approved labeling. 

Aquatic Species 

 

It is difficult to assess the risks posed to aquatic species from the use of cedarwood oil 

since uses are contained or indoors. However, in order to assess any potential risk to 

aquatic life from cedarwood oil, the Agency has evaluated the use of the registered fly 

repellent for horses as a worst case scenario. The label states that a horse can be sprayed 

with 32 oz of the end product containing 0.50% cedarwood oil as an active ingredient 
(equivalent to 0.004 mg/L of ai.). The Agency has assumed that after spraying, the horse 

might visit a farm pond (quarter acre pond) where all of the cedarwood oil washes off the 

animal after immersion in the pond. Although, cedarwood oil is not water soluble, the 

Agency has estimated exposure concentrations in the top 1 foot of water at 0.014 mg/L 

(Appendix B). Since the Agency has waived Tier I aquatic toxicity data, an estimate of 

acute toxicity (100 mg/L) was used to assess the potential hazard to fish and aquatic 

organisms. In order to define potential risk, the Agency calculated aquatic risk quotients 

(RQ) as an exposure/hazard ratio and derived an RQ = 0.00014 which is lower that the 

acute aquatic LOCs (0.05 – 0.5) by about two orders of magnitude. This suggests that risk 

to aquatic organisms from cedarwood oil exposure in an aquatic environment is very low 

and that there is a no effect (NE) to aquatic endangered/threatened species. 

III. References 

1) EPA Minimum Risk Pesticides. Criteria for FIFRA 25 (b) exemption. 

2) California EPA (2001) California Environmental Protection Agency Department of 

Pesticide Regulation, USEPA/OPP Pesticide Related Database Queries: Cedarwood Oils. 

3) EPA (1993) Reregistration Eligibility Decision (RED) Cedarwood Oils. Washington, 

DC, US Environmental Protection Agency, EPA 738-S-93-012, 169 pp. 
Appendix A. Extrapolated Toxicity Values Used to Estimate a Worst Case Scenario 

for Potential Toxic Exposure of Cedarwood Oil to Avian and Mammalian Species. 

Acute and Chronic RQs are based on the Upper Bound 

Kenaga Residues.

Chemical Name: The maximum single day residue estimation is used for 

 Use both the acute and reproduction RQs.

 Formulation

Application Rate 0.024 lbs a.i./acre RQs reported as "0.00" in the RQ tables below should be noted as

<0.01 in your assessment. This is due to rounding and significant

figure issues in Excel.

Half-life 0.125 days 

Application Interval 0.125 days

Maximum # Apps./Year 8

Length of Simulation 1 year

Mallard duck LD50 (mg/kg-bw) 5000.00

Bobwhite quail LC50 (mg/kg-diet) 5000.00

Mallard duck NOAEL(mg/kg-bw) 0.00

Mallard duck NOAEC (mg/kg-diet) 0.00

5000.00

5000.00

0.00

0.00

Kenaga

Values

Short Grass 5.76

Tall Grass 2.64

Broadleaf plants/sm Insects 3.24

Fruits/pods/seeds/lg insects 0.36

Avian Results

Avian Body Ingestion (Fdry) Ingestion (Fwet) % body wgt FI

Class Weight (g) (g bw/day) (g/day) consumed (kg-diet/day)

Small 20 5 23 114 2.28E-02

Mid 100 13 65 65 6.49E-02

Large 1000 58 291 29 2.91E-01

Avian Body Adjusted LD50

Weight (g) (mg/kg-bw)

20 2596.13

100 3305.00

1000 4668.44

small mid large

20 g 100 g 1000 g

Short Grass 6.56 3.74 1.67

Tall Grass 3.01 1.71 0.77

Broadleaf plants/sm Insects 3.69 2.10 0.94

Fruits/pods/seeds/lg insects 0.41 0.23 0.10

20 g 100 g 1000 g

Short Grass 0.00 0.00 0.00

Tall Grass 0.00 0.00 0.00

Broadleaf plants/sm insects 0.00 0.00 0.00

Fruits/pods/seeds/lg insects 0.00 0.00 0.00

Acute Chronic

Short Grass 0.00 #DIV/0!

Tall Grass 0.00 #DIV/0!

Broadleaf plants/sm Insects 0.00 #DIV/0!

Fruits/pods/seeds/lg insects 0.00 #DIV/0!

Endpoints

LC50 (mg/kg-diet)

Avian

Dietary-based RQs RQs

(Dietary-based EEC/LC50 or 

NOAEC

Avian Acute RQs Dose-based RQs 

(Dose-based EEC/adjusted LD50)

Avian Classes and Body Weights Dose-based EECs 

(mg/kg-bw) 

 Upper Bound Kenaga Residues For RQ Calculation

Dietary-based EECs (ppm)

NOAEL (mg/kg-bw)

NOAEC (mg/kg-diet)

Mammals

LD50 (mg/kg-bw)

cedarwood oil

repelent

spray

)
cedarwood oil repelent Upper bound Kenaga Residues

Mammalian Results

Mammalian Body Ingestion (Fdry) Ingestion (Fwet) % body wgt FI

Class Weight (g bwt/day) (g/day) consumed (kg-diet/day)

15 3 14 95 1.43E-02

Herbivores/ 35 5 23 66 2.31E-02

insectivores 1000 31 153 15 1.53E-01

15 3 3 21 3.18E-03

Grainvores 35 5 5 15 5.13E-03

1000 31 34 3 3.40E-02

Mammalian Body Adjusted Adjusted

Class Weight LD50 NOAEL

15 10989.15 0.00

Herbivores/ 35 8891.40 0.00

insectivores 1000 3845.80 0.00

15 10989.15 0.00

Grainvores 35 8891.40 0.00

1000 3845.80 0.00

15 g 35 g 1000 g 15 g 35 g 1000 g

Short Grass 5.49 3.80 0.88

Tall Grass 2.52 1.74 0.40

Broadleaf plants/sm Insects 3.09 2.13 0.50

Fruits/pods/seeds/lg insects 0.34 0.24 0.06 0.08 0.05 0.01

Acute Chronic Acute Chronic Acute Chronic

Short Grass 0.00 #DIV/0! 0.00 #DIV/0! 0.00 #DIV/0!

Tall Grass 0.00 #DIV/0! 0.00 #DIV/0! 0.00 #DIV/0!

Broadleaf plants/sm insects 0.00 #DIV/0! 0.00 #DIV/0! 0.00 #DIV/0!

Fruits/pods/lg insects 0.00 #DIV/0! 0.00 #DIV/0! 0.00 #DIV/0!

Seeds (granivore) 0.00 #DIV/0! 0.00 #DIV/0! 0.00 #DIV/0!

Acute Chronic

Short Grass 0.00 #DIV/0!

Tall Grass 0.00 #DIV/0!

Broadleaf plants/sm insects 0.00 #DIV/0!

Fruits/pods/seeds/lg insects 0.00 #DIV/0!

Dietary-based RQs 

(Dietary-based EEC/LC50 or 

NOAEC)

Mammal RQs

15 g mammal 35 g mammal 1000 g mammal Dose-based RQs 

(Dose-based EEC/LD50 or NOAEL)

Granivores

Mammalian Classes and Body weight

Dose-Based EECs 

(mg/kg-bw)

Herbivores/ insectivores
Appendix B. Expected Aquatic Exposure Residues Calculations for a Quarter Acre 

Pond 

Given: 

1 acre-foot = the amount of water that would cover 1 acre to a depth of 1 foot. This is 

equivalent to 43,560 cu ft. or 1,233,482 L of water. Therefore, a quarter acre pond has the 

equivalent volume in the surface 1 foot of water of 308,370 L. 

Given: 

4 oz of end product is equivalent to 113.5 g. If the cedarwood oil represents 0.50% of the 

net this is equal to 0.57 g of cedarwood oil ai. Therefore, a 32 oz container would contain 

about 904 g of total product or 4.52 g (4,520 mg) of cedarwood oil. 

Assume the entire 32 oz of fly repellent spray (0.50% cedarwood oil) is used on a 900 lb 

horse with a surface area of 32.2 ft 

Assume that horse visits the quarter acre pond; as a worst case scenario the horse is 

completely immersed in the water and 100% of the cedarwood oil is released into the 

water. 

If the cedarwood oil is dissipated rapidly within the top 1 ft of water, this will result in 

about 0.014 mg/L of cedarwood oil released into the environment (0.014 mg/L = 4,520 

mg/308,370 L). Since cedarwood oil is not very water soluble, the residues will be 

concentrated at or near the surface. 

Assume that the LC50 for fish and the EC50 for daphnia is > 100 mg/L, respectively (since 

ecotoxicity data have been waived we assume that an acute toxicity end point is > 100 

mg/L as would have been determined from an aquatic limit test). 

The calculation of risk quotients (RQs) are as follows: 0.014 mg/L/ 100 mg/L = 0.00014. 

This RQ value is below the Agency’s aquatic acute level of concern (LOC = 0.05 – 0.5) 

by about three orders of magnitude and suggests that exposure to cedarwood oil should 

result in little or no risk to fish and aquatic invertebrates.