UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

PCCode.: 179701 

DP Barcode: 411405 

Date: 12/05/2014 

MEMORANDUM 

To: 

Through: 

d-Limonene: Ecological Risk Assessment for Registration Review 

Nell Anderson, Branch Chief 

Risk Management and Implementation Branch 

Pesticide Re-evaluation Division 

Dana Spatz, Branch Chief 

Environmental Risk Branch lll 

Environmental Fate and EffectS Division 

From: for James K. Wolf, Ph.D., Soil Physicist 

Katherine Stebbins, Biologist

Environmental Risk Branch Ill 

Environmental Fate and Effects Division 

Peer Review: Melissa Panger, Ph.D., Senior Scientist 

JamesHetrickPh.D., Senior Advisor 

Rosanna Louie-JuzwiakRAPL

Environmental Risk Branch Ill 

Environmental Fate and Effects Division 

This memorandum transmitsthe Environmental Fate and Effects Division's (EFED) ecological

risk assessment for d-limonene. The results of this screening-level risk assessment indicate: 

For broadcast/directed spray applications of d··llmonene: 

The rnajor risk concerns are for potential effects to terrestrial invertebrates. Although 

thereareno toxicity data to derive: risk quotients, risk is assumed based on the fact that 

this pesticide is registered for use as an insecticide. 
2 

 The level of concern is also exceeded for non‐target plants inhabiting areas near the

treated field (i.e., within 15 feet).

 Acute and chronic risk has been identified for mammals. Although this chemical is

practically non‐toxic to mammals, the risk identified in this assessment can be attributed

to very high application rates (i.e., up to 55 lb a.i./A).

 Effects are not expected for birds (and reptiles) at the lower rates modelled and risks

are uncertain at the higher rates (e.g., 34 and 55 lb a.i./A).  Risk to birds on a chronic

exposure basis is also uncertain due to a lack of data.  

 Effects are not expected for fish, amphibians, aquatic invertebrates and plants.

For small scale applications of d‐limonene (aerosol spray, crack and crevice, etc.):

 Effects to mammals, birds, plants and aquatic animals are not expected

 Effects to terrestrial invertebrates are of concern.

At this time, there have been no data submitted to assess the risk to pollinators.  d‐limonene is

registered for use as an insecticide and is generally applied via foliar applications, thus, data are

needed in order to conduct an assessment for pollinators; namely, bees.  The following studies

are recommended to support this assessment.  

These studies include:

1. Honey Bee Adult Acute Contact Toxicity (Guideline 850.3020)

2. Acute oral toxicity to adult honey bees (Non‐guideline, OECD TG 213)

3. Acute oral toxicity to larval honey bees (Non‐guideline, OECD TG 237)

4. Chronic oral toxicity to adult honey bees (Non‐guideline)

5. Chronic oral toxicity to larval honey bees (Non‐guideline)

6. Honey bee toxicity of residues on foliage (Guideline 850.3030)

7. Field trial of residues in pollen and nectar (Non‐guideline)

8. Semi‐field testing for pollinator (Non‐guideline, OECD Guidance 75)

9. Field testing for pollinators (Guideline 850.3040)

 
3 

I.EXECUTIVE SUMMARY 

 

A. Nature of the Stressor

Limonene (d‐limonene) [(4R)‐1‐methyl‐4‐(1‐methylethenyl)cyclohexene; CAS No, 5989‐27‐5] is a

naturally occurring chemical obtained from the rind of citrus fruits. Limonene is a hydrocarbon

classified as a cyclic terpene. The chemical exists as two optical isomers, d‐ and l‐limonene, and

the d/l‐racemic mixture. The limonene enantiomer, or active ingredient (a.i.) under review is the

d‐enantiomer (i.e., the dextrorotatory enantiomer). This dextrorotatory enantiomer has the R‐

absolute configuration. In this assessment, unless otherwise specified, the term “limonene” is

used interchangeably with “d‐limonene.”  

d‐limonene is used as an acaricide, herbicide, insecticide, and also as an insect repellent/feeding

depressant. There are a variety of uses registered including: agricultural crops (citrus, pome

fruits, grapes, etc. ), ornamental plants, Christmas tree plantations, fencerows, recreational

areas, wood protection, and many indoor uses (see Appendix 1 for a comprehensive listing of the

types of registered uses). Limonene is not applied aerially. Limonene can be applied using

sprayers (ready‐to‐use containers, hooded sprayers, pump sprayers, pressurized containers),

aerosol containers (cans), impregnated strips, injection equipment or with a sponge. The labels

for the d‐limonene registrations suggest a wide range of potential treatment areas [i.e., spot

treatment (ft2

) to crops (acres)]. With applications such as spot treatments or edge/perimeter

treatments, the application rates used in the exposure models often lead to uncertainty in the

exposure estimates (e.g., scaling spot treatment applications up to an acre). The maximum

number of applications and maximum yearly application rate, and reapplication interval are also

not specified for many registrations (labels).  

There is a wide range of application rates when a treatment area is specified with rates that

range from 4.6 to 55.2 lb a.i./A per application for treating ornamentals and for herbicidal use in

agricultural crops. The maximum yearly rate is 415.2 lb a.i./A/yr.  

The insecticidal mode of action of limonene is believed to be similar to pyrethrum ‐ by affecting

the sensory nerves of the peripheral nervous system (not a cholinesterase inhibitor)1. As an

herbicide, d‐limonene is a non‐systemic, contact herbicide that strips the waxy rind or cuticle

from plants, causing death of the plant by desiccation2.

The major route of dissipation for d‐limonene is volatilization. Other dissipation processes

include photodegradation in air, microbial‐mediated aerobic soil metabolism, sorption to soil,

and transport in runoff water. Limonene is stable to hydrolysis. The vapor pressure (2 mm Hg @

20 ̊C) and Henry’s Law Constant (2.6 x 10‐2 atm‐m3

/mole) indicates that limonene is highly

volatile and that it will readily volatilize from soil and water. However, this dissipation process

competes with binding. Limonene binds strongly to soil (Koc > 1000 mL/goc), therefore it is

 

1

Ware, G.W. and Whitacre, D.M. 2004. The Pesticide Book. 6th Edition. Pg. 66 2

 Stephen O. Duke, Joanne G. Romagni, Franck E. Dayan 2000. Natural products as sources for new mechanisms of herbicidal action. Crop 

Protection 19 (2000) 583-589. 
4 

expected to be relatively immobile in soils. Because aerobic metabolism studies have not been

submitted for d‐limonene, published aerobic biodegradation studies were used to estimate a

first order biotransformation rate with a half‐life of 38.5 days. Under anaerobic conditions, d‐

limonene appears to be persistent.

  

B. Summary of Effects and Risk Conclusions

 

For broadcast/directed spray applications of d‐limonene:  

o The major risk concerns are for potential effects to terrestrial invertebrates.

Although there are no toxicity data to derive risk quotients, risk is assumed based

on the fact that this pesticide is registered for use as an insecticide.

o The level of concern is also exceeded for non‐target plants inhabiting areas near

the treated field (i.e., within 15 feet).

o Acute and chronic risk has been identified for mammals. Although this chemical is

practically non‐toxic to mammals, the risk identified in this assessment can be

attributed to very high application rates (i.e., up to 55 lb a.i./A).

o Effects are not expected for birds (and reptiles) at the lower rates modelled and

risks are uncertain at the higher rates (e.g., 34 and 55 lb a.i./A). Risk to birds on a

chronic exposure basis is also uncertain due to a lack of data.  

o Effects are not expected for fish, amphibians, aquatic invertebrates and plants.

For small scale applications of d‐limonene (aerosol spray, crack and crevice, etc.):

o Effects to mammals, birds, plants and aquatic animals are not expected

o Effects to terrestrial invertebrates are of concern.

II.PROBLEM FORMULATION 

A. Pesticide Type, Class, and Mode of Action  

Limonene (d‐limonene) [(4R)‐1‐methyl‐4‐(1‐methylethenyl)cyclohexene; CAS No, 5989‐27‐5] is a

naturally occurring chemical obtained from the rind of citrus fruits. Limonene is a hydrocarbon

classified as a cyclic terpene. Specifically, it is a monoterpene. Limonene has a chiral

(stereogenic) carbon. Thus, limonene occurs as an enantiomeric pair (i.e., as two non‐

superimposable mirror‐image chemical structures and therefore, each enantiomer is optically

active3. The structure of d‐limonene is shown in Figure 1. The limonene enantiomer under review

is the d‐enantiomer (i.e., the dextrorotatory enantiomer). This dextrorotatory enantiomer has

the R‐absolute configuration. In this assessment, unless otherwise specified, the term

“limonene” is used interchangeably with “d‐limonene.”

 

3 The chirality of limonene arises from an asymmetric carbon atom (i.e., carbon is the chiral/stereogenic center). The odors of l‐

limonene and d‐limonene are different; l‐limonene smells piney and turpentine like and d‐limonene has a pleasing orange

scent. This is associated with enantiomer‐specific interactions with chiral olfactory receptors. 
5 

Figure 1. Structure of d‐Limonene

The insecticidal mode of action of limonene is believed to be similar to pyrethrum ‐ by affecting

the sensory nerves of the peripheral nervous system (not a cholinesterase inhibitor)4. As an

herbicide, d‐ limonene is a non‐systemic, contact herbicide that strips the waxy rind or cuticle

from plants, causing the plant to desiccate, resulting in the death of the plant5.

The major route of dissipation for d‐limonene is volatilization. Other dissipation processes

include photodegradation in air, microbial‐mediated aerobic soil metabolism, sorption to soil

(e.g., organic carbon), and transport in runoff water (IPCS, 19986). Functional groups of

limonene, cyclohexane ring and ethylene group, are not prone to hydrolysis. Microbial mediated

degradation is an important degradation pathway. Degradation rates in aerobic sewage sludge

have been reported to range from 41‐98% degradation in 14 days to >93% degradation in 14

days. Biotic degradation of limonene has been observed with some specific microorganisms.

These studies were not designed to determine the biodegradation rates of limonene, but

suggested that limonene biodegradation (biodegradability in aerobic aqueous medium, OECD,

19927)  was occurring as the biochemical oxygen demand ranged from 41 to 98% in 14 days

(IPCS, 1998). Because aerobic metabolism studies have not been submitted for d‐limonene,

published aerobic biodegradation studies were used to estimate a first order biotransformation

rate (d‐1); for a half‐life of 38.5 days8,9 (Appendix 2). Under anaerobic conditions, d‐limonene

appears to be persistent. In the atmosphere d‐limonene will photo‐chemically degrade

producing hydroxyl and nitrate radicals and ozone.  

B.Overview of Pesticide Use and Usage

The production of d‐limonene and use in flavorings, fragrances, cosmetics, as a solvent, a

wetting agent, and in the manufacture of resins may result in its release to the environment

through various waste streams. d‐limonene is also found in many oils and fruits and is emitted to

the environment from plants and the combustion of wood. d‐limonene is used as both an active

 

5 Ware, G.W. and Whitacre, D.M. 2004. The Pesticide Book. Pg. 66 5 Stephen O. Duke, Joanne G. Romagni, Franck E. Dayan 2000. Natural products as sources for new mechanisms of herbicidal action. Crop

Protection 19 (2000) 583‐589. 6 IPCS, 1998. http://www.inchem.org/documents/cicads/cicads/cicad05.htm 7 OCED, 1992. http://www.oecd.org/chemicalsafety/risk‐assessment/1948209.pdf 8 Misra, G. and Pavlostathis, S.G., 1997. Biodegradation of monoterpenes in liquid and soil‐slurry systems. Appl. Microbiol. Biotech. 47:572‐577. 9 Rifai, H.S. and C.J. Newell. 1998. Estimating First‐Order Decay Rates for BTEX Using Data from 115 Sites, in Proceedings of the 1998 NGWA

Conference on Petroleum Hydrocarbons and Organic Chemicals in Ground Water: Prevention, Detection and Restoration, Nov. 11 ‐ 13,

Houston, Texas, pp. 31 – 41, National Ground Water Association, Westerville, OH.
6 

and inert ingredient in pesticide formulations. d‐limonene is used as an acaricide, herbicide,

insecticide, and insect repellent/feeding depressant. Formulations include an emulsifiable

concentrate, impregnated material, pressurized liquid, and a ready‐to‐use liquid. A summary of

use sites is shown in Table 1.  

Table 1. Summary of Use Sites Registered for d‐limonene 

Use Sites  Groups

Terrestrial Citrus fruits, cole crops, flavoring/spice crops, fruiting vegetables,

grapes, leafy vegetables, legume vegetables, pome fruits, root and

tuber vegetables, small fruits, tree nuts, Christmas trees; Nursery

stock; Ornamentals (plants, trees, turf); Outdoor buildings and

structures(perimeter); sidewalks, rights‐of‐

ways/fencerows/hedgerows; Refuse/solid waste sites/Manure;

Recreational Areas; Sewage systems; Wood protection treatment

to buildings/products

Indoor Household/domestic dwellings

Commercial/institutional/industrial premises/vehicles

Dogs/ Cats; Pet living/sleeping quarters

Human body‐clothing while being worn

Wide area general indoor treatment (public health)  

Wood protection treatment to buildings/products

   

Limonene is not applied aerially. It is applied using ground sprayers (ready‐to‐use containers,

hooded sprayers, pump sprayers, and pressurized containers), aerosol containers (cans),

impregnated strips, injection equipment, or manually with a sponge. There is a wide range of

limonene concentrations and application rates for the formulated products. Because many of

the uses are “spot” treatments or edge or boundary use, the application rates used in the

exposure models lead to uncertainty.  

  

Many of the labels for d‐limonene do not provide a complete application rate (e.g., the label may

say to spray for 10 seconds or only states a concentration in lb/gal without a finish spray

volume). Current models used by EFED to estimate exposure require application rates on a per

unit area basis (e.g., lb a.i./A). Other label issues are the lack of a maximum yearly (or seasonal)

rate, the number of applications per year, or the reapplication interval. Additionally, because of

the large range in rates, this assessment has focused on the labels with the highest application

rates.  

The aquatic exposure assessment is focused on the AvengerTM AG Burndown Herbicide (EPA Reg.

No. 82052‐4) and the Orange Guard Ornamental Plants Protection Concentrate (EPA Reg. No.

61887‐3) products, both of which specify the application rates on a per area basis. With single

application rates as high as 34.6 lb a.i./A for the AvengerTM AG Burndown Herbicide and 55.2 lb

a.i./A for the insecticide Orange Guard Ornamental Plants Protection Concentrate, these

products provide an upper‐bound screen for aquatic exposures. The burndown herbicide

product can be applied to a variety of agricultural crops as a broadcast or spot treatment with

ground equipment such as a directed sprayer or hooded sprayer. When the application rate of
7 

34.6 lb a.i./A is used, the herbicide is applied as a spray over the target vegetation. The label

does not specify a maximum number of applications or a yearly application rate. However,

additional information was provided to clarify the intended use indicating a maximum of 12

applications with a 2‐day minimum reapplication interval10. Literature suggests that repeat

applications may be necessary for larger weeds.11,12,13 The Orange Guard product is intended for

use as a foliar (insecticide) spray to protect ornamental plants and when factoring in the high

finished spray volumes, the rates are as high as 55.2 lb a.i./A (with up to six applications/yr at a

7‐day interval).  

For the terrestrial exposure assessment, additional scenarios were selected to bound the

potential exposures to terrestrial organisms. Thus, in addition to the scenarios discussed above,

the lower rates on the Orange Guard label (4.6 and 18.4 lb a.i./A) were also quantitatively

assessed. These additional scenarios also bracket the non‐broadcast labeled uses such as the

perimeter treatment, mound sprays and spot treatments with rates such as 0.454 lb a.i./sq ft

(19.79 lb /A for moss and algae control on lawns) and 0.2265 lb a.i./mound (assuming 40

mounds/A = 9.06 lb a.i./A). While these “per acre” extrapolations are high, they are the values

that would be used in the TREX model to estimate the residues on feed items within the

spot/area treatment that the animal may be foraging.  

Given the low toxicity of d‐limonene, the small scale applications (aerosol spray, crack and

crevice, etc.), were not quantitatively assessed in this assessment. Table 2 provides an overview

of the uses that are considered representative of the highest use patterns. The application rates

in bold were selected for exposure modeling. For a complete list of all d‐limonene uses see

Appendix 1.  

 

 

 

 

 

 

 

 

 

10 Correspondence from S. McIntosh to R. Wasem (April 11, 2014). 11 http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=6498 12 http://www.groworganic.com/avenger‐weed‐killer‐conc‐32‐oz.html 13 http://avengerorganics.com/LinkClick.aspx?fileticket=sWUA%2BS%2BCs6g%3D&tabid=81
Table 2. Overview of Representative High Exposure d‐limonene Uses  

Crop/Site Product/ Reg. number Timing; App. Type Method/ Equipment

Maximum

Single

Application

Rate (lb a.i./A)

Max Rate

Per Year

lb a.i./A

Max.

Num.

Apps.

/Yr

MRI

(d) 

Ornamental plants in

greenhouses, nurseries,Christmas tree

plantations, andlandscapes (residentialcommercial, industrial)

Orange Guard‐Ornamental

Plants (5.8%)

Insecticide/Repellent61887‐3

FoliarBroadcast

Ground

Sprayer/Pump

sprayer/

Handheld

4.6 27.6

6 7

Rates 

0.092 

finish 

gal/A; 

100‐40

sq ft, 6

18.4 110.4

36.8 220.840.1 240.6

55.2 331.2

Ag. Crops: Brassica veg;

citrus; grapes; herbs;

leafy veg; legume veg;

pome fruit; root & tuber

veg; small fruit; stonefruit; tree nuts

AvengerTM AG

Burndownherbicide (55%)82052‐4a

Weed post‐

emergence/burndownBroadcast andSpot treatment

Ground

Sprayer‐

Directed

/Hooded

sprayer

34.6 415.2 12b 2b Label 

produa.i./ga

Borders arounddriveways, patios,sidewalks, mature treesand ornamentals,buildings, residentialgreenhouses, fencerows,flowerbeds

Avenger WeedKiller Conc.(70%)/ RTU(17.5%)82052‐182052‐3

Weed post‐emergence/burndownPerimeter/Spot

Ground

Sprayer

1.28‐1.47 lb

a.i./gal (dilution)

51‐59 lb a.i./A*

NS 12b 2b

*Assudid nocomplon labuncerttreatmscenause.

a Label provides sprayer requirements: Do not use nozzles or nozzle configurations which produce fine droplets (mist). Use low drift, low pressure no

operate on the ground or skimming across ground surface

b The minimum retreatment interval was not specified on the label but the registrant suggested every 2 days for difficult to treat weeds.    
9 

Limonene Usage  

 

National‐level pesticide usage data for d‐limonene is not available. d‐limonene usage data has

been reported by the California Department of Pesticide Regulation Pesticide Use Reporting and

was summarized by USEPA’s Biological and Economic Analysis Division (BEAD) (Table 3).   

 

Table 3. Limonene Usage Data:  California, 2001‐2012 

Year  Pounds A.I. Applied

(Aga & Non Agb Applications) 

Cumulative Acres Treated

(Ag Only)

2001 40,703 34,695

2002 37,393 39,562

2003 28,072 48,939

2004 14,349 49,320

2005 45,877 62,359

2006 32,843 75,333

2007 68,949 79,012

2008 45,536 64,151

2009 56,495 55,465

2010 56,403 29,621

2011 14,460 10,025

2012 17,976 73,328

AVG  42,662  51,818

Source: California DPR, 2010, Summary of Pesticide Use Report Data, Use Trends of Biopesticide Pesticides:

http://www.cdpr.ca.gov/docs/pur/pur10rep/10sum.htm

C. Previous Ecological Risk Assessments and Evaluations 

 

The ecological risk assessment for the Reregistration Eligibility Decision (RED), completed in

September 1994 (EPA 738‐R‐94‐034), was based on a limited number of environmental fate and

ecological toxicity studies. Exposure concentrations for the risk assessment were estimated using

simple screening level exposure models and limited toxicity data. The risk assessment concluded

that minimal risk is anticipated for birds, mammals, and aquatic animals for the pesticidal uses of

limonene. EFED believed at that time that applications of limonene did not pose any undue risks

to endangered species. The 1994 assessment prepared for the RED did not include a terrestrial

or aquatic plant assessment because limonene was not registered as an herbicide at that time.

Additionally, several new uses have been registered (for example, the Burndown Herbicide‐

AvengerTM AG) so the rates in this current assessment are substantially higher than previous

assessments. Additional ecological data for plants (terrestrial and aquatic) have also been

submitted and considered in this assessment along with additional mammal data that was cited

in the 2007 TRED (the previous assessment was based on a non‐definitive acute oral endpoint

and did not consider any chronic data).  
10 

Although, no additional environmental fate data has been submitted, published literature was

reviewed and used to confirm previously used values or change or add an additional value (e.g.,

degradation or dissipation process), if appropriate. The Food and Drug Administration (FDA)

considers limonene to be Generally Recognized as Safe (GRAS) as a food additive when used as a

synthetic flavoring substance and adjuvant (21 CFR §182.60).

III.Risk Hypothesis and Conceptual Model 

A. Measures to Evaluate Risk Hypotheses 

In the case of d‐limonene, measures of exposure are based on terrestrial and aquatic exposure

models14 that estimated environmental concentrations (EEC) of d‐limonene using maximum

labeled application rates. The T‐REX model (version 1.5.2) was used to produce terrestrial EECs

on wildlife food items. The STIR model was not used in this assessment because inhalation

toxicity data were not available. The TerrPlant and AgDRIFT models are used to estimate

exposure to nontarget plants. The Surface Water Concentration Calculator (SWCC15; version

1.106) (see Section III A. 1) and the linked PRZM/EXAMS with PE516 are used to produce aquatic

EECs and drinking water EDWCs. Because the SWCC currently does not include volatilization

from soil, whereas PRZM does, aquatic exposure (EECs) concentrations were refined with

PRZM/EXAMS for the scenarios that resulted in the highest concentrations estimated by SWCC.

Both consider volatilization from water. Limited monitoring data for air and water are available,

but these data were collected in studies that were not specifically targeted for the pesticidal uses

of limonene.   

Measures of effect are obtained from a suite of studies conducted with a limited number of

surrogate species. The lowest toxicity endpoints for the most sensitive surrogate test species are

used to estimate treatment‐related effects on growth, reproduction and/or survival.

B.         Risk Hypothesis 

For this assessment, the risk to non‐target organisms is based on potential effects from the

application of d‐limonene to the environment. The Agency presumes the following risk

hypothesis for this screening level assessment:

Based on mode of action, the proposed use patterns, and the sensitivity of non‐target 

aquatic and terrestrial species, the proposed uses of d‐limonene have the potential to 

reduce survival, reproduction, and/or growth in terrestrial and aquatic animals and plants 

through direct application, spray drift and/or runoff. 

 

14http://www.epa.gov/pesticides/science/models_pg.htm   15 http://www.epa.gov/oppefed1/models/water/index.htm#swcc 16 PE5 suite of models (PE5 v5.0, PRZM v3.12.2, EXAMS v2.98.04.06) and scenarios
11 

In order for a chemical to pose an ecological risk, it must reach non‐target organisms at

concentrations found to cause adverse effects. The assessment of ecological exposure pathways

in this assessment includes an examination of the source and potential migration pathways to d‐

limonene exposure, and the determination of potential adverse effects on non‐target species.

C.         Conceptual Model  

Application methods for d‐limonene involve foliar spray via ground equipment. Ecological

receptors that may potentially be exposed to d‐limonene include terrestrial and semi‐aquatic

wildlife (i.e., mammals, birds, amphibians, terrestrial invertebrates, and reptiles) and plants. In

addition, aquatic receptors (e.g., freshwater and estuarine/marine fish and invertebrates,

amphibians, and plants) may also be exposed as a result of potential movement of d‐limonene

via spray drift and/or runoff from the site of application to aquatic environments. Exposure to

terrestrial animals is based primarily on dietary consumption of foliar residues while aquatic

assessments assume that all major potential routes of direct exposure are accounted for. The

major transport pathway for d‐limonene is volatilization. 

IV. Measures of Exposure 

Limonene functions as an acaricide, herbicide (including moss and algae pests in terrestrial

environments), and also as an insecticide/repellent. The insecticide/repellent uses tend to be

more of a spot treatment in nature, whereas the herbicide uses can include spot treatment,

perimeter/border treatment, or treatments to a field (although the applications are generally

directed applications rather than full‐acre broadcast treatments).  

The environmental fate data for this assessment was generally obtained from open literature

data such as the World Health Organization (IPCS, 199817) and Limonene (CICAD#5, 199818),

TOXNET (200619) and USEPA High Production Volume Information System (HPVIS), 201420 and

are essentially the same as the previous assessment conducted for the RED. These sources

generally report the same information because they tend to cross‐reference each other. Data

values from these sources were generally selected to be consistent with the RED (1994) and the

USEPA OPPT Screening Level Hazard Characterization of Monoterpene Hydrocarbon

Category.21,22 Additional information was included when available. Chemical identification and

physical‐chemical properties of limonene are shown in Table 4. When available, experimental

physical‐chemical properties are reported. Exposure concentrations were estimated using simple

screening level exposure models.  

 

17 IPCS, 1998. http://www.inchem.org/documents/cicads/cicads/cicad05.htm 18 CICAD#5, 1998. http://whqlibdoc.who.int/publications/1998/9241530057.pdf 19 TOXNET, 2006. http://toxnet.nlm.nih.gov/cgi‐bin/sis/search/a?dbs+hsdb:@term+@DOCNO+1809 20 http://www.epa.gov/chemrtk/hpvis/hazchar/Category%20Monoterpenes_Sept2009.pdf 21 http://www.epa.gov/hpvis/hazchar/Category%20Monoterpenes_Sept2009.pdf 22 http://ofmpub.epa.gov/oppthpv/quicksearch.display?pChem=101509
12 

A.Environmental Fate and Modeling Input Parameters 

Physical/Chemical and Environmental Fate Properties 

The physical/chemical properties and environmental fate properties of d‐limonene are listed in

Table 4. 

 

 

Table 4. Identity and Physical‐Chemical Properties of d‐limonene 

Type of Information  Information  Source 

Chemical name   IUPAC: (R)‐4‐isopropenyl‐1‐

methylcyclohexene  

or p‐mentha‐1,8‐diene

CAS (4R)‐1‐methyl‐4‐(1‐

methylethenyl)cyclohexene

http://www.alanwood.net/pesticides/d‐

limonene.html

Pesticide type Acaricide, herbicide, insecticide,

repellent/feeding depressant  

Pesticide Labels

CAS Reg. No.   d‐ limonene: 5989‐27‐5

Racemate: 7705‐14‐8

 l‐ Limonene: 5989‐54‐8

http://www.alanwood.net/pesticides/d‐

limonene.html

Empirical Formula C10H16

http://www.alanwood.net/pesticides/d‐

limonene.html

Smiles String C(=CCC(C(=C)C)C1)(C1)C   

Molecular mass (g/mol)   136.23 CICAD#5, 1998; IPCS, 1998

Physical State Liquid (colorless) CICAD#5, 1998; IPCS, 1998

Specific gravity   0.8411 g/cm3 (7.4 lb/gallon) CICAD#5, 1998; IPCS, 1998

Melting point  ̊C  ‐74.35 CICAD#5, 1998; IPCS, 1998

HPVIS, 2014

Boiling point  ̊C 175.5‐178.6 @ 760 mm Hg

176 @ 760 mm Hg

CICAD#5, 1998; WHO, 1998

HPVIS, 2014a

Solubility in water (mg/L) 13.8 @ 25 ̊C   Massaldi and King, 197323.  

[J. Chem. Eng. Data, 1973, 18:393‐397]

CICAD #5, 1998; IPCS, 1998

HPVIS, 2014

Vapor pressure  

                           

1 mm Hg @ 20 ̊C  

2 mm Hg @ 20 ̊C 

3 mm Hg @ 14.4 °C

1.43 mm Hg @ 20 ̊C (measured)

1.2 mm Hg @ 20 ̊C

1.59 mm Hg @ 20 ̊C

MRID 93136002

MRID #46511103 (Product Chemistry)

EPA HQ‐OPP‐2004‐0335‐003.pdf

IPCS, 1998; HPVIS, 2014

HPVIS, 2014

FFHPVC Terpene Consortiumb,

Henry’s Law Constant

(calculated)

1.3 x 10‐2 atm‐m3/mole @ 20 ̊C [1

mm Hg]

1.8 x 10‐2 atm‐m3

/mole @ 20 ̊C [1.43

mm Hg]

(Solubility – 13.8 mg/L)

Copolovici and Niiements, 2005

 

23 http://pubs.acs.org/doi/pdf/10.1021/je60059a024
13 

Type of Information  Information  Source 

2.6 x 10‐2 atm‐m3/mole @ 20 ̊C [2 

mm Hg] 

2.8 x 10‐2 atm‐m3

/mole @ 20 ̊C

2.8 x 10‐2 atm‐m3

/mole @ 25 ̊C

3.2 x 10‐2 atm‐m3

/mole

SRC as cited by TOXNET, 2006

Enthalpy of Vaporization   kj/mole (kcal/mole) 

37.8 ( 9.03) to 49.9 (11.93)

Chickos J.S. and Acree, W.E. 2003..J. Phys.

Chem. Ref. Data. 32:519‐877.

http://www.chemicaldictionary.org/dic/D/D‐

Limonene_332.html

Clará et al. 2009. J. Chem. Eng. Data 54:1087‐

1090.

Copolovici and Niiements, 2005

Organic Carbon Partition

Coefficient  

(Koc) (mL/goc)

1,300

1,030 to 4,780 (estimated)

1,260 (estimated)

TOXNET, 2006; CICAD#5, 1998;  

IPCS, 1998; 1030  

HPVIS, 2014

Log Kow (n‐octanol/water

partition coefficient)

4.88; 4.83 @ 25 ̊C (calculated)

4.23 @ 20 ̊C (measured)

4.50 @ 25oC

CICAD#5, 1998; IPCS, 1998; HPVIS, 2014.

Copolovici and Niiements, 2005

Log Ko‐air  (octanol‐air

partition coefficient)

4.26   (estimated; EPISuite)

pKa/pKb Not applicable  ‐ 

Bioconcentration Factor

(BCF)

246 to 262 (estimated from log Kow

4.23)

660 (estimate from log Kow 4.57)

CICAD#5

TOXNET, 2006

Aqueous Photolysis Half‐

life [t1⁄2](days)

0.037 days (reported as 0.884 hours) HPVIS, 2014

FFHPVC Terpene Consortiumb,c

Estimated, AOPWIN, EPI Suite 2000

Foliar Dissipation Rate   Estimated 2.79 to 4.67 ppm/hour MRID 47548301 aHPVIS, 2014. High Volume Information System:

http://www.epa.gov/chemrtk/hpvis/hazchar/Category%20Monoterpenes_Sept2009.pdf b http://ofmpub.epa.gov/oppthpv/document_api.download?FILE=Summaries%20sn133.pdf

c http://www.epa.gov/hpv/pubs/summaries/monoterp/c13756rt.pdf

Environmental Fate/Exposure Summary 

Much of the physicochemical and environmental fate values for d‐limonene are based upon

values reported in literature and were estimated by models such as EPI (Estimate Program

Interface) Suite24 and were obtained from a variety of published sources (CICAD #5, 1998;

TOXNET, 2006; HPVIS, 2014; SRC, 2014; IPCS, 1998). While there is variability in the values

reported in literature, the conclusion derived in this assessment would be the same (low

solubility, volatile, low mobility in soil, photodegradable in air, and biodegradable under aerobic

conditions) (Clará et al., 2009; Copolovici and Niinemets, 2005). Also, some of the measured data

may actually be the d/l‐limonene (racemic mixture) rather than d‐enantiomer (i.e., d‐limonene).

Where values are available both for the d‐ and d/l‐limonene, they are generally similar in order

 

24 EPI Suite,2014  http://www.epa.gov/opptintr/exposure/pubs/episuite.htm
14 

of magnitude. The routes of dissipation for d‐limonene include volatilization, photodegradation

in air, microbial‐mediated aerobic soil metabolism, and binding to soil/sediment (IPCS, 1998;

TOXNET, 2006).

Limonene is stable to hydrolysis. Microbial mediated degradation is an important degradation

pathway as biotic degradation of limonene has been observed with some microorganisms in

some pure microbial cultures25. Degradation in aerobic sewage sludge has been reported to

range from 41‐98% degradation in 14 days. These studies were not designed to determine the

biodegradation rates of limonene, but suggested that limonene biodegradation (biodegradability

in aerobic aqueous medium, OECD, 199226) was occurring as the biochemical oxygen demand

ranged from 41 to 98% in 14 days. Because aerobic metabolism studies have not been submitted

for d‐limonene, published aerobic biodegradation studies were used to estimate a first order

biotransformation rate for the d‐limonene; resulting in a half‐life of 38.5 days27,28 (Appendix 2).

Under anaerobic conditions, d‐limonene appears to be persistent.  

In the atmosphere, volatilized limonene undergoes rapid bi‐molecular gas‐phase reactions with

ozone, nitrate radicals, and photochemically generated hydroxyl radicals. Volatilization half‐lives

from water were estimated to range from 1 hour to 5 days, for a river and a lake model,

respectively (TOXNET, 2006). Photodegradation in air of d‐limonene is an important degradation

pathway in the atmosphere. Degradation mechanisms have been associated with hydroxyl

radicals (t1/2=0.32 to 2 hours), ozone (t1/2=0.18 to 2.6 hours), and nitrite radicals (t1/2=0.08 to

0.015 hours) (TOXNET, 2006). Photodegradation products in air are: hydroxyl radical degradation

products including 4‐acetyl‐1‐methylcyclohexane, a ketoaldehyde, formaldehyde, 3‐oxobutanal,

glyoxal, and C10 dicarbonyl; ozonolysis degradation products including

bis(hydroxymethyl)peroxide, hydrogen peroxide; and nitrite radical degradation products include

formaldehyde, acetaldehyde, formic acid, acetone, and prooxyacetyl nitrate.  

A study [MRID 47648301] was submitted for QRD 400/QRD 416 for a residue trials for mustard

greens. QRD 400 (total 18.5% a.i.) and QRD 416 (total 17.43% a.i.) contain a mixture of 3 active

ingredients terpenes α‐terpinene, ρ‐cymene, and d‐limonene. The two products were applied to

mustard green foliage at a rate of 2.6 and 2.4 lb a.i./A for QRD 400 and QRD 416, respectively.

Leaves were harvested at 0‐, 1‐, and 4‐ hours. d‐limonene levels generally dropped below the

limit of quantification (LOQ=0.05 ppm) at 1‐hour. Although, a half‐life could not be determined,

the rate of decline for d‐limonene ranged from 2.8 to 4.67‐hr. Adjusting the 2.4 or 2.6 lb a.i./A to

the maximum rate for d‐limonene (34.6 lb a.i./A), the time required for the d‐limonene

concentrations to drop below the LOQ ranged between 3 and 15 hours (Table 4).

 

25 Amaral, J.A., Keins, A., Richards, S.R., and Knowles, R. 1998. Effect of Selected Monoterpenes on Methane Oxidation,

Denitrification, and Aerobic Metabolism by Bacteria in Pure Culture. Applied and Environmental Microbiology, Vol 64(2), pp

520‐525. 26 OCED, 1992. http://www.oecd.org/chemicalsafety/risk‐assessment/1948209.pdf 27 Misra and Pavlostathis. 1997. Appl. Microbiol. Biotechnol. 47:572‐577. 28 Rifai and Newell, 1998. https://info.ngwa.org/GWOL/pdf/982664575.PDF
15 

The estimates of soil organic carbon partitioning coefficient (Koc) for d‐limonene ranged between

1,030 and 4,780 mL/goc (SRC, 2014; CICAD#5, 1998, WHO, 1998). Based on the FOA mobility

classification, d‐limonene is expected to be slightly mobile in soil29. It would tend to bind to

eroded soil and be transported in runoff water. However, the high vapor pressure (1 to 3 mm

Hg) and calculated Henry’s Law Constants ranged between 1.3 x 10‐2 and 3.2 x 10‐2 atm‐

m3

/mole, depending upon the vapor pressure value and solubility (7.54 to 13.8 mg/L), indicate

that limonene will readily volatilize from soil and water (Table 4). However, this dissipation

process competes with binding.

The estimated log octanol‐water partition coefficients (Kows) range from 4.23 to 4.83 indicates

potential bioaccumulation. However, the bioconcentration factor, calculated on the basis of

water solubility and the log octanol/water partition coefficient, ranged 246 to 262 suggesting

that limonene is not expected to bioaccumulate in fish and other aquatic organisms. TOXNET

(2006) gives an estimated BCF value of 660. A log Kow between 4 and 8, would typically trigger

use of the KABAM model to determine if there are food chain concerns for birds and mammals

from consuming aquatic organisms with accumulated residues, however, because of the low BCF

values, the high Henry’s Law Constant showing high volatility from water, and low/non‐definitive

toxicity for birds and mammals, this analysis was not conducted.

Monitoring Data Detections in Environmental Media  

Limonene residues have been detected in rural, urban, suburban, and forest areas in the U.S.

and in other countries. These residues have been detected in air, surface water, ground water,

seawater, wastewater, ice, soils, and in solid waste composting facilities. Levels of limonene are

varied, but the limited data do not allow for a correlation with usage or geographical region.  

The National Water Quality Assessment Program (NAWQA, 2014) database for d‐limonene

reports 481 samples collected in ambient surface of water, 602 groundwater samples, and 296

treated water supplies. The limit of detection appears to range from 0.013 to 0.5 μg/L). The

maximum concentration was 1.2, 0.072 and 0.157 μg/L, in surface water, groundwater, and

treated water supplies, respectively. These monitoring studies were not targeted and many were

conducted prior to the registration of AvengerTM Burndown pesticide (EPA. Reg No. 82052‐4).

The CICID#5 (1998) and TOXNET (2006) reported (Table 5) detections observed in a number of

media from other studies. The detections of limonene (or d‐limonene) in these monitoring

studies may reflect sources other than pesticidal use (i.e., sewage treatment).

   

 

29 USEPA. 2006. Standard Soil Mobility Classification Guidance. Memorandum From S. Bradbury to Environmental Fate and

Effects Division. April 21, 2006. Environmental Fate and Effects Division. Office of Pesticide Programs. United States

Environmental Protection Agency.
16 

Table 5. Concentrations of Limonene (or d‐limonene) observed in monitoring studies collected 

from various media. 

Medium  Concentration Source

Outdoor Air 0.036 to 32 μg/m3 CICAD#5, 1998

Lake Water 0.47 to 84 ng/L CICAD#5, 1998

Drinking Water Max.   30 ng/L (5 of 14 samples)  

Max. 1.87 x 105 ng/L (1 of 182 samples

CICAD#5, 1998

Estuary 25 to 633 ng/L CICAD#5, 1998

River Water 590 to 1,600 ng/L CICAD#5, 1998

Sea Water 2 to 40 ng/L CICAD#5, 1998

Ground Water (sewage contaminated) 1,000 to 130,000 ng/L TOXNET, 2006

Waste Water, Influent, sewage treatment plant Non‐detect to 220,000 ng/L CICAD#5, 1998

Sediment 105 to 807 ng/kg CICAD#5, 1998

Ice 4 to 15 ng/L CICAD#5, 1998

Surface Water 0.013 to 1.2* μg/L (17 of 481) NAWQA, 201430

Bottom Material 15.4 to 111.1* μg/kg (6 0f 35) NAWQA, 2014

Groundwater 0.016 and 0.072* μg/L (2 of 602) NAWQA, 2014

Treated Water Supply 0.028 to 0.157 μg/L (4 of 296) NAWQA, 2014 * Concentrations are estimated.

Ecological Effects Characterization 

 

There is a limited toxicity data set for d‐limonene. Tables 6 and 7 summarize the available data

for the aquatic and terrestrial taxonomic groups, respectively. The tables provide a preliminary

overview of the potential acute toxicity of d‐limonene by providing the acute toxicity

classifications.  

Aquatic Organisms 

On an acute exposure basis, d‐limonene is classified as “slightly toxic” to freshwater fish and

invertebrates. Data are not available to characterize the effects to aquatic organisms on a

chronic exposure basis, or for estuarine/marine animals on an acute basis. For aquatic plants,

blue green algae (Anabaena flos‐aquae) was the most sensitive non‐vascular plant with

reductions in yield at all test concentrations [blue green algae; EC50 = 9.353 mg a.i./L and NOAEC

<3.125 mg a.i./L], thus, the EC05 (1.731 mg a.i./L)will be used as a proxy for the NOAEC. For non‐

vascular plants, the EC50 and NOAEC were 29.65 and 3.125 mg a.i./L, respectively, based on

reductions in frond yield for duckweed (Lemna gibba).  

   

 

30 http://cida.usgs.gov/nawqa_queries_public/
17 

Table 6. Summary of Aquatic Toxicity Studies for d‐Limonene 

 

Taxonomic 

Group 

Study 

Type 

Surrogate 

Species 

and 

Test Material 

Toxicity Value 

 

MRID  and 

Classification 

Acute 

Toxicity 

Classification 

Freshwater

fish

Acute

Rainbow trout

(Oncorhynchus 

mykiss)

LC50 = 80 mg a.i./Lb 00146085

(Acceptable) Slightly toxic  

Chronic No Data 

Freshwater

invertebrates

Acute

Water flea

(Daphnia 

magna)

EC50 = 39 mg a.i./L 00146085

(Acceptable) Slightly toxic

Chronic No Data 

Estuarine/

marine fish

and

invertebrates

No Data

Aquatic

plants and

algae

Non‐

vascular

Blue‐green

algae a

(Anabaena 

flos‐aquae)

EC50 =  9.353 mg a.i./L (nominal)

 (95% C.I.: 7.4 to 11.8)  

NOAEC = <3.125 mg a.i./L

EC05=1.731 mg a.i./L

Based on reductions in yield  

49044004

(Supplemental‐

quantitative)  

N/A

Vascular

Duckweed     

(Lemna gibba)

EC50=29.65 mg a.i./L (nominal)

(95% C.I.: 19.84 to 44.32 )

NOAEC: 3.125 mg a.i./L  

Based on reductions in frond yield

49044001  

(Supplemental‐

quantitative) N/A

a For non‐vascular plants (e.g., algae, diatom), four species were tested and the values from the most sensitive test species

are reported. b Exceeds the solubility according to the Fate Section‐DER does not mention any precipitate

 

 

Terrestrial Organisms 

 

Data are not available to assess the toxicity of d‐limonene to birds on an acute oral basis. On a

sub‐acute/dietary exposure basis, d‐limonene is classified as “practically non‐toxic” to birds

based on a LC50 of >5,600 mg a.i./kg diet and a lack of sublethal effects reported for the

Bobwhite quail (Colinus virginianus). Data are not available to assess the risk on a chronic

exposure basis. For mammals, d‐limonene is classified as “practically non‐toxic” on an acute

exposure basis. On a chronic exposure basis, a 2‐generation reproductive study was not available

so the NOAEL for the rat (250 mg a.i./kg/day) was based on reductions in body weight gain at
18 

500 mg a.i./kg/day treatment level in the available developmental toxicity study. Data are not

available to assess the toxicity of d‐limonene exposure via inhalation.  

For terrestrial invertebrates, there are no toxicity studies available to assess the risk to terrestrial

invertebrates. Given that d‐limonene is registered as an acaricide/insecticide, the acute contact

toxicity to the honey bee (Apis mellifera) is a data gap.

For terrestrial plants, there were no effects reported in the available seedling emergence study,

thus, the NOAEC is ≥265‐345 lb a.i./A (MRID 49044005). In the vegetative vigor toxicity study,

there were effects reported at all treatment levels so the EC05was used as a proxy for the NOAEC

(Monocots‐ EC25: 2.83 lb a.i./A; EC05 = 0.19 lb a.i./A‐Dicots EC25=7.09 lb a.i./A; EC05 = 1.31 lb a.i./A)

which was based on reductions in dry weight (MRID 49098302).  

 

Table 7. Summary of the Terrestrial Toxicity Studies for d‐Limonene  

Taxonomic 

Group 

Study Type 

and test 

material  

Surrogate Species  Toxicity Values (all units in 

terms of measured a.i.) 

MRID and 

Classification 

Acute 

Toxicity 

Classifica‐

tion 

Mammals

Acute Orala‐ 

Technical

Mouse

(Mus musculus) 

5600 mg/kg‐bw (M)  

TRED, 2005 Practically

Non‐toxic

6600 mg/kg‐bw (F)  

Laboratory rat    

(Rattus norvegicus)

4400 mg/kg‐bw (M)  

5100 mg/kg‐bw (F)  

Chronica,b‐  

Technical

Laboratory rat      

(Rattus norvegicus)

NOAEL: 250 mg/kg/day

LOAEL: Small reductions

in maternal body weight

gain were observed at

500 mg/kg.b

RED, 1994 N/A

Birds

Acute‐Oral   No Data

Subacute

Dietary

(Technical)

Bobwhite quail        

(Colinus virginianus)

LC50 = >5,600 mg /kg‐bw

No sublethal effects

reported

MRID 00146988

(Acceptable)

Terrestrial

Invertebrates

Acute

(contact/oral) No Data  

 
19 

Terrestrial

Plants

Vegetative

Vigor

Dicot‐cabbage

EC25: 7.09 lb a.i./A

NOAEC:  <7 lb a.i./A based

on reductions in dry

weight

EC05 = 1.31 lb a.i./A

49098302

(Acceptable)   N/A  

Monocot‐corn

EC25: 2.83 lb a.i./A

NOAEC:  <8 lb a.i./A,

based on reductions in

dry weight

EC05 =0.19 lb a.i./A

Seedling

Emergence  

Dicot EC25:  Not determined  

NOAEC ≥265‐345 lb a.i./A

49044005

(Supplemental‐

Qualitative)

N/A 

Monocot

a Study reviewed by HED  

b Reviewer’s Note: Slight but statistically significant and dose‐dependent increases in the number of liters and 10

fetuses with 14 ribs instead of 13 were observed at 500 and 1000 mg/kg/day. These effects are considered variations

in skeletal formation, were not accompanied by other effects, are secondary to maternal toxicity and do not represent

a concern for developmental toxicity of limonene.

V. ANALYSIS 

A.Exposure Modeling

The input parameters used in this aquatic and terrestrial modeling assessment are selected from

the environmental fate data available in open literature or estimated (i.e., EPI‐Suite). Input

parameters were generally in accordance with US EPA‐OPP EFED water model parameter

selection guidelines, Guidance for Selecting Input Parameters in Modeling the Environmental

Fate and Transport of Pesticides31 or with “best professional judgment”. Detailed information

about the models, selection of input parameters and scenarios can be obtained from

http://www.epa.gov/oppefed1/models/water/index.htm.

Aquatic Modeling 

Potential aquatic exposures were initially estimated using the Surface Water Concentration

Calculator (SWCC; Version 1.106, 05/22/2014) and the Pesticide Root Zone Model (PRZM,

version 3.12.3, June 2006) and Exposure Analysis Modeling System (EXAMS; version 2.98.04.06,

April 2005), linked with the PE5.pl input shell (November 2006). PRZM/EXAMS was used to refine

the surface water exposure concentrations for aquatic exposure for the ecological assessment.

Both models simulate the fate and transport of pesticides on the agricultural field (PRZM) and

the fate and resulting daily concentrations of pesticides that reach an adjacent water body

 

31 Parameters are selected as per Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of

Pesticides; Version 2.1, October 22, 2009.
20 

through runoff, erosion, and spray drift (EXAMS). Both models consider volatilization from a

surface water body, but currently only PRZM has the capacity to consider volatilization from the

soil. Neither model addresses the volatilization from a plant surface (i.e., target plant).

Additionally, both models were developed for “field” crops, therefore, considerable uncertainty

exists when scaling down from a per acre to per square foot basis.  

Simulations are based on crop‐specific scenarios developed to represent environmental

conditions at sites with a generally high runoff vulnerability. Aquatic ecological exposure is

estimated using the “standard pond” scenario based on a 10‐ha field bordering a 1‐ha water

body, 2‐m deep (20,000 m3

) with no outlet. Weather and agricultural practices are simulated for

30 years so that the 10‐year exceedance probability at the site can be estimated. The simulation

was generated using 30 years of meteorological data, encompassing the years from 1961 to

1990.

Aquatic Model Inputs 

The method of chemical application for both models is assumed to be ground spray (ground in

SWCC) and (CAM = 1 for PRZM/EXAMS). d‐limonene is (generally) applied as a foliar spray to

weeds; both models assume the pesticide is applied to soil or foliarily to the crop by considering

crop emergence and harvest dates and not the target weeds. Pesticide application management

inputs and spray drift parameters are summarized in Table 8. Ground spray methods were

assumed for both the preemergence and postemergence applications defined by each scenario.

For the non‐crop uses (i.e., spot treatment, boundary treatments, wood treatment), the

application rates are assumed to be less than the crop uses (on a per acre basis).

 

Table 8. PRZM/EXAMS Input Parameters for d‐Limonene

Input Parameter  Value Reference/Discussion 

#/Maximum Appl. Rate/Interval

(#/lb a.i./A; reapply interval; days)

12 app @ 34.6; 2 days

6 app @ 55.2; 7 days

8.5 gallons product/A (label)

Molecular Weight (g/mole) 136.23 Calculated

Henry’s Law Constant  

(atm‐m3

/mol)

2.6 x 10‐2 Calculated

Vapor Pressure @ 20oC (torr)   2  MRID 46511103

Enthalpy of Vaporization  

(kj/mole (kcal/mole))  

REQUIRED for PRZM to include

volatilization.

37.8 ( 9.03) to 49.9

(11.93)

10.48 = numerical

mid‐point between

low and high values.

Chickos J.S. and Acree, W.E. 2003.

http://www.chemicaldictionary.org/dic/D/D‐

Limonene_332.html

Clara et al. 2009. J. Chem. Eng. Data 54:1087‐1090.

Solubility (mg/L) @ 25oC 13.8 Massaldi and King, 1973

Aqueous Photolysis Half‐life

[t1⁄2](days)a

Stable No data

Hydrolysis [t1⁄2]@ pH 7 (days) Stable ‐

Aerobic Soil Half‐life [t1⁄2] (days) 33.53

[estimated]

Misra and Pavlostathis. 1997. Appl. Microbiol.

Biotechnol. 47:572‐577.

Rifai and Newell, 1998.

https://info.ngwa.org/GWOL/pdf/982664575.PDF
21 

Input Parameter  Value Reference/Discussion 

Did not multiple single value times 3a.

Aerobic Aquatic Half‐life [t1⁄2] (days) 67.1 Estimated 2 times the aerobic soil metabolism

half‐life.

Anaerobic Aquatic Half‐life [t1⁄2]

(days)

Stable No data

Organic Carbon Partition

Coefficient (Koc) (mL/goc)

1,300 Estimated range 1,030 to 4,780 CICAD#5, 1998;

IPCS, 1998; 1,300 a specific value given in TOXNET,

2006

Diffusion coefficient of pesticide in

air (DAIR) (cm2

/day)

4,300 PRZM Manual

Pesticide Application    

Maximum Application Rates:

       (EPA Reg. #; 82052‐4)

       (EPA Reg. #; 61887‐3)

Labels

12 applications @ 34.6 lb a.i/A, 2 day reapplication interval

  6 applications @ 55.2 lb a.i./A, 7 day reapplication interval

Chemical Application Method     

          Model

         PRZM/EXAMS (CAM)

         SWCC

  

Ground Spray

= Soil applied CAM=1

= Ground

Defined by model

Application Efficiency

(PRZM/EXAMS/SWCC) 0.99 EFED Guidance

    Drop Size Distribution

     (PRZM/EXAMS/SWCC)

         Very Fine to Fine 

           [EPA Reg No. 61887‐3]

     Fine to Medium/Coarse 

         [EPA Reg. No. 82052‐4]

Boom Height:          

Low  

High   

Low

High

Ground Spray

Ecological Spray Drift Fraction

0.027

0.062

0.011

0.017 a Although EFED guidance generally recommends multiplying single soil half‐life measurements by 3 in order to account for

variability, a 3x factor was not applied to the aerobic soil metabolism half‐life because the biodegradability test suggested rapid

degradation. Little difference was observed in the estimated EECs when the aerobic metabolism value was multiplied by 3.

  

Several uncertainties exist in the environmental fate input parameters in large part because

many are estimates rather than measured. The aerobic soil metabolism half‐life value estimated

from the biodegradation rates of several monoterpenes including limonene in liquid and soil‐

slurry systems and the aerobic aquatic metabolism half‐life was estimated from the aerobic soil

metabolism value. Greater uncertainty is probably due to limitations in the volatilization routines

in the models. Another major uncertainty is the use rates and number of applications of d‐

limonene.

Aquatic Modeling Results 

The initial EECs (Appendix 3, Table 1) for aquatic exposure were estimated, without volatilization,

for a number of uses using the SWCC. Aquatic RQs for aquatic invertebrates would exceed the

LOC of 0.05 for some scenarios. The scenarios that resulted in the highest concentrations with

the SWCC were rerun using PRZM/EXAMS, with PE5, with volatilization included in PRZM. The

aquatic exposure EECs estimated using PRZM/EXAMS are presented in Table 9. d‐limonene

concentrations in surface water are presented for the PRZM/EXAMS with and without the

volatilization routine turned on in PRZM.  Volatilization reduced the peak aquatic EECs from 80
22 

to 95% depending upon the scenario. The highest peak value across the different scenarios

(323.6 μg/L) was used for the exposure value in this assessment. Representative outputs from

the different models are presented in Appendix 4.

 

Table 9. Surface Water: Aquatic Exposure: PRZM/EXAMS d‐limonene estimated Peak, 96‐hour, 21‐

day and 60‐day average concentrations in standard farm pond for maximum rates with and 

without volatilization (in PRZM).  

Scenario

(1st app: mn/day)

Volatilization

with PRZMb

Peak 96‐hr 21‐day 60‐day

μg/L

NC Sweet Potato n   2478 1737 732 340

(5/15) y   113.0 95.6 85.5 38.6

GA Pecan n 3542 2450 1045 464

(5/15) y 225.3 168.8 114.9 55.7

TN Nursery n 2179 1646 881 459

(3/16) y 217.7 177.1 116.9 57.8

NJ Nursery n 1659 1565 1389 784

(01/01) y 323.6 309.6 272.0  210.9

FL Strawberry n 2240 1625 583 244

(10/03) y 124.7 98.5 77.5 35.6 a Application rate: 12 application @ 34.6 lb a.i./A; 2 day interval. b n is without volatilization and y is with volatilization in PRZM‐(volatilization is simulated in EXAMS for both)

 

Terrestrial Exposure Modeling‐Animals  

For this assessment, the exposure scenario modeled for terrestrial animals is for a foliar spray via

ground equipment, which is representative of the post‐ emergence/burndown herbicide uses as

well as the insecticide/repellent uses (e.g., ornamentals, nurseries). The EEC values used for

terrestrial animal exposure are derived from the Kenaga nomograph, as modified by Fletcher et 

al. (1994), based on a large set of actual field residue data. The upper limit values from the

nomograph represent high end residue values from actual field measurements (Hoerger and

Kenaga, 1972). The Fletcher et al. (1994) modifications to the Kenaga nomograph are based on

measured field residues from 249 published research papers, including information on 118

species of plants, 121 pesticides, and 17 chemical classes.   

Terrestrial exposure estimates (EECs) for avian and mammalian risk assessments were derived

using the T‐REX model (version 1.5.1) (Tables 10‐14) and were based on the products with the

highest application rates for the different use patterns (Table 2). The default 35‐day foliar half‐

life value was used for modeling EECs on terrestrial food items, however, see the Risk

Description section for further discussion regarding a shorter half‐life value. A complete

description of the input parameters and output is contained in APPENDIX 5.   

   
23 

Table 10. EECs on Potential Food Items Following Label‐Specified Applications of d‐limonene Using 

the T‐REX Model (ppm).

USE   Rate       

(lb a.i./A) 

DIETARY‐BASED 

EECs  

KENAGA VALUES

(Upper Bound)

 

Orange Guard‐ Ornamental  

6 apps. ; 7‐day retreatment 

interval 

4.6

Short Grass 4,816

Tall Grass 2,207

Broadleaf plants 2,709

Fruits/pods/seeds 301

Arthropods 1,886

18.4

Short Grass 19,265

Tall Grass 8,830

Broadleaf plants 10,836

Fruits/pods/seeds 1,204

Arthropods 7,545

55.2

Short Grass 57,795

Tall Grass 26,489

Broadleaf plants 32,509

Fruits/pods/seeds 3,612

Arthropods 22,636

Avenger Burndown

Herbicide Agricultural

Crops                                     

12 apps.; 2‐day retreatment

interval

34.6

Short Grass 80,893

Tall Grass 37,076

Broadleaf plants 45,502

Fruits/pods/seeds 5,056

Arthropods 31,683

Table 11. Avian Dose‐based EECs (mg/kg‐bw)/Avian Classes and Body Weights (grams) for Orange 

Guard‐ Ornamental plants in Greenhouses, nurseries, Christmas tree plantations, and landscapes 

(6 applications per year, 7‐day retreatment interval) 

Food Item 

Rate= 4.6       (lb a.i./A)  Rate=18. 4    (lb a.i./A)  Rate= 55.2       (lb a.i./A) 

Small  Med.  Large  Small  Med.  Large  Small  Med.  Large 

Short Grass   5,485 3,128 1,400 21,941 12,512 5,602 65,822 37,535 16,805

Tall Grass   2,514 1,434 642 10,056 5,734 2,567 30,169 17,203 7,702

Broadleaf plants 3,085 1,759 788 12,342 7,038 3,151 37,025 21,113 9,453

Fruits/pods 343 195 88 1,371 782 350 4,114 2,346 1,050

Arthropods 2,148 1,225 548 8,593 4,900 2,194 25,780 14,701 6,582

Seeds 76 43 19 305 174 78 914 521 233

 
24 

Table 12. Avian Dose‐based EECs (mg/kg‐bw)/Avian Classes and Body Weights (grams)‐Avenger 

Burndown Herbicide – Agricultural Crops (12 applications per year, 2‐day retreatment interval) 

Food Item 

Rate‐34.6 lb a.i./A  

small  med.   large 

Short Grass   92,129 52,536 23,521

Tall Grass   42,226 24,079 10,780

Broadleaf plants 51,823 29,551 13,231

Fruits/pods 5,758 3,283 1,470

Arthropods 36,084 20,577 9,212

Seeds 1,280 730 327

 

 

Table 13. Mammalian Dose‐based EECs (mg/kg‐bw)/Mammal Size Classes and Body Weights 

(grams) for Orange Guard‐ Ornamental plants in greenhouses, nurseries, Christmas tree 

plantations, and landscapes (6 applications per year, 7‐day retreatment interval) 

Food Item 

Rate= 4.6       (lb a.i./A)  Rate= 18.4    (lb a.i./A)  Rate= 55.2    (lb a.i./A) 

Small  Med.  Large  Small  Med.  Large  Small  Med.  Large 

Short Grass   4,592 3,174 736 18,368 12,694 2,943 55,103 38,083 8,830

Tall Grass   2,105 1,455 337 8,418 5,818 1,349 25,255 17,455 4,047

Broadleaf plants 2,583 1,785 414 10,332 7,141 1,656 30,995 21,422 4,967

Fruits/pods 287 198 46 1,148 793 184 3,444 2,380 552

Arthropods 1,798 1,243 288 7,194 4,972 1,153 21,582 14,916 3,458

Seeds 64 44 10 255 176 41 765 529 123

 

 

Table 14. Mammalian Dose‐based EECs (mg/kg‐bw)/Mammal Size Classes and Body Weights 

(grams) for Avenger Burndown Herbicide – Agricultural Crops (12 applications per year, 2‐day 

retreatment interval) 

Food Item 

Rate‐34.6 lb a.i./A  

small  med.   large 

Short Grass   77,125 53,304 12,359

Tall Grass   35,349 24,431 5,664

Broadleaf plants 43,383 29,983 6,952

Fruits/pods 4,820 3,331 772

Arthropods 30,207 20,877 4,840

Seeds 1,071 740 172

 

Plants 

Exposure to terrestrial plants is estimated using the TerrPlant (v1.2.2) screening model. TerrPlant

estimates potential exposure from a single application using default assumptions for runoff (2%

given solubility is between 10 and 100 ppm) and spray drift (1% given a ground application of a
25 

liquid formulation) (Table 15). Because there were no effects in the seedling emergence study,

this assessment only considers the exposure via spray drift (runoff is not included). See

APPENDIX 6 for more information.

 

Table 15. EECs on Plants Following Label‐Specified Ground Applications of d‐limonene Using the 

TerrPlant Model (lb a.i./A) 

USE  RATE

(lb a.i./A) 

EECs from 

Spray Drift  

Orange Guard‐ Ornamental   18.4 0.184

55.2 0.551

Avenger Burndown‐Ag. Crops 34.6 0.346

 

VI.     Risk Characterization 

A.     Risk Estimation ‐ Integration of Exposure and Effects Data 

Toxicity data and exposure estimates are used to evaluate the potential for adverse ecological

effects on non‐target species. For this screening‐level assessment of d‐limonene the

deterministic risk quotient method is used to provide a metric of potential risks. The RQ is a

comparison of exposure estimates to toxicity endpoints; estimated exposure concentrations are

divided by acute and chronic toxicity values. The resulting unitless RQs are compared to the

Agency’s levels of concern (LOCs) (see Table 16), which are the Agency’s interpretive policy such

that when LOCs are exceeded, the need for regulatory action may be considered. These criteria

are used to indicate when the use of a pesticide, as directed on the label, has the potential to

cause adverse effects on non‐target organisms.

Table 16. Agency Levels of Concern (LOC).  

Risk Description RQ Taxa

Acute Potential for acute risk to non‐target organisms

which may warrant regulatory action in

addition to restricted use classification

acute RQ > 0.5 aquatic animals,

mammals, birds

Acute Listed

Species

Listed species may be potentially affected by

use

acute RQ > 0.05 aquatic animals

acute RQ > 0.1 mammals and

birds

Chronic Potential for chronic risk may warrant

regulatory action, listed species may potentially

be affected through chronic exposure

chronic RQ > 1 all animals

Non‐Listed and

Listed Plant  

Potential for effects in non‐listed and listed

plants

RQ > 1 all plants
26 

1. Non‐target Aquatic Animals and Plants 

On an acute exposure basis, d‐limonene is classified as “slightly toxic” to freshwater fish and

invertebrates. With a peak EEC of 323.6 ug a.i./L, the resulting RQ values were below the LOC

thresholds (acute and ES) at 0.004 and 0.0083 for fish and invertebrates, respectively (Table 17).

However, this is based on a limited toxicity set with only one species of freshwater fish tested

and no data for estuarine/marine (E/M) species (fish or invertebrates). In the absence of data,

the freshwater species will serve as a surrogate for E/M species, however, there is uncertainty

with using freshwater values as a proxy for E/M species, especially given that only one species of

freshwater fish was tested.  

Toxicity data are not available to assess the risk to fish and invertebrates on a chronic exposure

basis.  Based on the highest 60‐day EEC (210.9 ug/L), and the acute toxicity value for fish (80,000

ug/L), d‐limonene would need to be 379 times more toxic on a chronic exposure basis to reach

the level of concern. Likewise, for invertebrates, based on the highest 21‐day EEC (272 ug/L) and

the acute toxicity value (39,000 ug/L), d‐limonene would need to be 143 times more toxic on a

chronic exposure basis to reach the level of concern. In an attempt to gain further information

on the chronic risk, a structure activity analysis (QSAR) was run but it did not provide useful

information because of the poor fit with the available acute data. When chronic data are lacking,

an acute to chronic ratio (ACR) may be used to inform for the taxa, but with no chronic data for

d‐limonene, this type of analysis is not possible for the active ingredient. As an alternative,

Raimondo et. al, (2007)32 provides an ACR value based on a dataset of 456 same species pairs of

acute and chronic data. Using the 90th percentile ACR values of 90.0 and 68.3 for fish and

invertebrates, respectively, there would not be any exceedances at the highest application rate.

There is, however, a high degree of variability in the estimated ACRs with ranges of (1.2‐2,121)

for fish and (1.1‐18,550) for invertebrates. While the majority of chemicals will likely have ACRs

at or below the 90th percentile mentioned above, there is the uncertainty of over or

underestimating the chronic risk given the high variability in the dataset. Based on the 90th

percentile ACR, risk is not anticipated at this time.    

There are no LOC exceedances for vascular and non‐vascular aquatic plants.   

Table 17. Aquatic Exposure RQ Values for d‐Limonene 

Taxonomic 

Group 

Exposure 

Type  Toxicity  (ug/L)  EEC        ( μg/L )  RQ 

Exceeds 

LOC 

(Y/N) 

Freshwater Fish Acute LC50 = 80,000 323.6 0.004 N

Freshwater

Invertebrate Acute LC50 = 39,000 323.6 0.008 N

Non‐listed EC50 = 9,353 323.6 0.035 N

 

32 Raimondo, S, Montague, B. , and Barron, M. (2007) Determinants of Variability in Acute to Chronic Ratios for 

Aquatic Invertebrates and Fish. Environ Toxicol Chem (26) No. 9 pp 2019-2023. 
27 

Taxonomic 

Group 

Exposure 

Type  Toxicity  (ug/L)  EEC        ( μg/L )  RQ 

Exceeds 

LOC 

(Y/N) 

Aquatic

Vascular plants   Listed NOAEC =1,731 323.6 0.187 N

Aquatic Non‐

Vascular

Non‐listed EC50 =29,650 323.6 0.011 N

Listed NOAEC = 3,125 323.6 0.104 N

Non‐Target Terrestrial Animals 

Mammals 

For the Orange Guard uses at the higher application rates (i.e., 18.4 and 55.2 lb a.i./A), there

were acute and endangered species (ES) LOC exceedances for the majority of size/dietary class

combinations (Table 18). The shaded cells indicate the acute LOC (0.5) exceedances and the bold

indicate the additional ES LOC (0.1) exceedances. The acute exceedances (i.e., LOC ≥0.5) range

from 0.64‐1.9 for the 18.4 lb a.i. rate and from 1.02‐5.7 for the 55.2 pounds a.i./A rate.  

In terms of chronic exposure, there were LOC exceedances (i.e., LOC ≥ 1.0) for the majority of

size/dietary class combinations and the exceedances ranged from 0.96‐33 and 1.19‐100 for the

18.4 and 55.2 lb a.i./A rates, respectively.  

For the lower rate (4.6 lb a.i./A), the acute RQ was exceeded for the small mammal eating short

grass exclusively (RQ=0.47) and the ES LOC was exceeded for all size classes eating short grass,

tall grass, and broadleaf plants and the small and medium mammals consuming arthropods

(Table 18).  

On a chronic exposure basis, there were exceedances that ranged from 1.5‐8.4 for the 4.6

pounds a.i./A rate.  

 

For the Avenger Burndown uses at the 34.6 lb a.i./A, applied every 2 days for a total of 12

applications, the RQs are higher than the scenarios for the Orange Guard. The acute RQs

exceedances ranged from 0.5‐7.98 and the chronic exceedances ranged from 1.67‐140 (Table 

19).  

   
28 

Table 18. Mammalian Dose Based RQs ‐ Orange Guard Ornamental plants in Greenhouses, 

nurseries, Christmas Tree plantations, and landscapes (6 applications per year, 7‐day retreatment 

interval) 

Food Item 

Rate 4.6 lb a.i./ A 

Small=15 g  Medium=35g  Large‐1000g 

Acute  Chronic  Acute    Chronic  Acute    Chronic 

Short Grass   0.47 8.36 0.41  7.14 0.22  3.83

Tall Grass 0.22  3.83 0.19  3.27 0.10  1.75

Broadleaf plants 0.27  4.70 0.23  4.02 0.12  2.15

Fruits/pods 0.03 0.52 0.03 0.45 0.01 0.24

Arthropods 0.19  3.27 0.16  2.80 0.09 1.50

Seeds 0.01 0.12 0.01 0.10 0.00 0.05

   Rate 18.4 lb a.i./ A 

Short Grass   1.90 33.43 1.62 28.55 0.87 15.31

Tall Grass 0.87 15.32 0.74 13.09 0.40  7.02

Broadleaf plants 1.07 18.80 0.91 16.06 0.49  8.61

Fruits/pods 0.12  2.09 0.10  1.78 0.05 0.96

Arthropods 0.74 13.09 0.64 11.18 0.34  5.99

Seeds 0.03 0.46 0.02 0.40 0.01 0.21

   Rate 55.2 lb a.i./ A 

Short Grass   5.70 100.29 4.87 85.66 2.61 45.92

Tall Grass 2.61 45.96 2.23 39.26 1.20 21.05

Broadleaf plants 3.21 56.41 2.74 48.19 1.47 25.83

Fruits/pods 0.36  6.27 0.30  5.35 0.16  2.87

Arthropods 2.23 39.28 1.91 33.55 1.02 17.98

Seeds 0.08 1.39 0.07 1.19 0.04 0.64

 

Table 19. Mammalian Dose Based RQs ‐ Avenger Burndown Herbicide – Agricultural Crops (12 

applications per year, 2‐day retreatment interval) 

Dose‐based RQs        

(Dose‐based 

EEC/LD50 or 

NOAEL) 

Rate 34.6  lb a.i./ A 

Small=15 g  Medium=35g  Large‐1000g 

Acute  Chronic  Acute    Chronic  Acute    Chronic 

Short Grass   7.98 140.37 6.81 119.90 3.65 64.27

Tall Grass 3.66 64.33 3.12 54.95 1.67 29.46

Broadleaf plants 4.49 78.96 3.83 67.44 2.05 36.15

Fruits/pods 0.50 8.77 0.43  7.49 0.23  4.02

Arthropods 3.12 54.98 2.67 46.96 1.43 25.17

Seeds 0.11  1.95 0.09 1.67 0.05 0.89
29 

Birds 

The toxicity data set for birds is limited as there are no acute oral or reproductive studies

(chronic exposure). Based on the available dietary exposure study, d‐limonene is classified as

“practically non‐toxic” with an LC50 value of >5,600 mg a.i./kg diet. Since the endpoint from this

study is non‐definitive (i.e., it is a ‘greater than’ value), it will not be used to calculate RQs.  

 

Terrestrial Invertebrates 

Data are not available to assess the risk to invertebrates.  

 

Non‐target Terrestrial Plants  

The risk to plants was assessed using TerrPlant (Appendix 6) and then refined with an analysis

using AgDrift (Appendix 7). From the TerrPlant analysis, there were no RQ exceedances for

applications at the 4.6 or 18.4 lb a.i./A rate. At the 34.6 and 55.1 lb a.i./A rates, there were LOC

exceedances (RQs= 1.8 and 2.9, respectively) for listed monocots (Table 20).  

Table 20. Screening Level Analysis‐Terr Plant RQs 

Plant Type 

Rate lb a.i./A  

18.4  34.6  55.1 

Monocot <0.1 0.12 0.20

Monocot (listed)   0.97 1.82  2.91 

Dicot <0.1 <0.1 <0.1

Dicot (listed) 0.14 0.26 0.42

Using the Ag Drift analysis, at the 4.6 lb a.i./A rate, the distance to no longer exceed the LOC

was 0‐3 feet for non‐listed species and 3‐23 feet for listed species. For the higher rates (18.4‐

55.1 lb a.i./A, the distance ranged from 3‐19 feet for non‐listed species and 9‐305 feet for listed

species (Table 21).  

Table 21. Ag Drift Analysis‐Distance from the Field to no longer exceed the LOC 

Product  Rate   Plant Type  Listed   Non‐listed 

Avenger              

Med‐Coarse Droplet    

34.6

Monocot 75.46 6.56

Dicot 9.84 3.23

Orange Guard     

(Fine Droplet)

4.6

Monocot 22.97 3.28

Dicot 3.28 0

18.4

Monocot 91.86 6.56

Dicot 13.2 3.28

55.2

Monocot 305.11 19.68

Dicot 39.37 9.84
30 

B.Risk Description 

 

Risks to Aquatic Organisms 

 

Animals 

On an acute exposure basis, the risk to freshwater fish and invertebrates is considered low. Data

are not available for estuarine/marine (E/M) species (fish or invertebrates). In the absence of

data, the freshwater species may serve as a surrogate for E/M species, thus, the acute risk is

anticipated to be low. However, there is uncertainty given the paucity of data for d‐limonene.  

Toxicity data are not available to assess the risk to fish and invertebrates on a chronic exposure

basis. Using the 90th percentile ACR (see earlier discussion of Raimondo et. al., in Risk

Characterization) to estimate the chronic toxicity values, risk is not anticipated for fish or

invertebrates at this time. However, given the high variability in the ACR analysis, having chronic

data for d‐limonene would greatly reduce the uncertainty in this assessment.  

 

Plants 

All of the RQs for aquatic vascular and non‐vascular plants are below the LOCs for risk to listed

and nonlisted species. Therefore, likelihood of direct risk to aquatic plants from the use of d‐

limonene is considered low.  

Risks to Terrestrial Organisms 

 

Mammals 

d‐limonene is classified as “practically non‐toxic” to mammals on an acute oral basis, however,

because of the high application rates and frequency of applications, the expected residues on

the dietary items are high at the 18.4, 34.6 and 55.1 lb a.i./A application rates/use scenarios,

thus leading to exceedances for the majority of size/dietary class combinations. At the 4.6 lb

a.i./A rate, the only exceedance for was the small mammal feeding exclusively on short grass.     

There is uncertainty with the exposure to terrestrial organisms for several reasons. Based on the

chemical properties/environmental fate data, d‐limonene is expected to volatilize rapidly (with a

vapor pressure of <3 mm of Hg). At this time there is only one study (MRID 47548301) that

characterizes the foliar dissipation half‐life and a minimum of 3 studies are needed to move

away from the 35‐day default assumption in the TREX model. To further explore the risk to

terrestrial animals from exposure to d‐limonene, the available magnitude of residues study was

reviewed and is considered here. The magnitude of residue study for mustard greens (MRID

47548301) tested two products (QRD 400/QRD 416 which contained a mixture of 3 active

ingredient terpenes, α‐terpinene, ρ‐cymene, and d‐limonene) that were applied to mustard

green foliage at a rate of 2.6 and 2.4 lb a.i./A for QRD 400 and QRD 416, respectively. Leaves

were harvested at 0‐, 1‐, and 4‐ hours. d‐limonene levels generally dropped below the Limit of

Quantification (LOQ=0.05 ppm) at 1‐hour. The rate of decline for d‐limonene ranged from 2.8 to

4.67‐hr. Adjusting the 2.4 or 2.6 lb a.i./A to the maximum rate for d‐limonene (34.6 lb a.i./A), the

time required for the d‐limonene concentrations to drop below the LOQ ranged between 3 and
31 

15 hours. This shorter half‐life also seems in‐line with the registrant suggested reapplication

intervals as short as every 2 days. To explore the expected residues on food items, the T‐REX

model was run using a foliar dissipation half‐life of 2 days. When the high end exposure scenario

(34 lb a.i./A, 12X, 2‐day interval) was modeled, the acute RQ exceedances ranged from 0.5‐ 1.6

and the chronic RQs ranged from 1.5‐ 28 for a variety of size/dietary classes. The lower exposure

scenario (4.6 lb a.i./A, 6X, 7‐day interval), did not have any acute LOC exceedances (the ES LOC of

0.1 was exceeded to small mammals feeding on short grass; RQ = 0.12) and for chronic exposure,

there were exceedances for small and medium mammals feeding on short grass and broadleaf

plants with RQs around 1.01‐2.10.   

Based on the available data, there are risks (acute and chronic) identified for mammals at the

higher foliar exposure scenarios (18.4, 34.6 and 55.1 lb a.i./A rates). At the lower rate of 4.6 lb

a.i./A (using the 2‐day half‐life), risk to mammals (acute) is not anticipated. While there is an

endangered species LOC exceedance (RQ=0.12) it is only for the 15 gram mammal feeding

exclusively on short grass. To refine further, the LD50 was reported separately for males and

females and the lowest value [4400 mg a.i./kg‐bw (M)] was used for the endpoint in this risk

assessment but if the higher value [5100 mg a.i./kg‐bw (F)] was used then there would be no

exceedances, thus, the risk is between an RQ of 0.10 and 0.12 for the 4.6 lb a,i./A rate.  

On a chronic exposure basis, there were exceedances for small and medium mammals feeding

on short grass and broadleaf plants with RQs around 1.01‐2.10. The TREX model indicates that

these exceedances would occur in 17 out of the 56 days (the application pattern is 6 applications

every 7 days), thus, the exceedances are likely occurring the day of application and lasting 1‐2

days.  For additional characterization, because the effect was a small reduction in maternal

weight gain, the LOAEC value (500 mg a.i./kg‐bw) was used to gauge if exceedances would occur

at the actual dose that caused the effect. When modeling the endpoint of 500 mg a.i./kg‐bw, the

only chronic exceedance was an RQ of 1.05 for the 15 gram mammal feeding exclusively on short

grass. Altogether, the risk to mammals is not considered high at the lowest application scenario.

Additional data for the foliar dissipation half‐life would reduce the uncertainty in this analysis.   

Birds 

Because there was no mortality or sublethal effects at the highest treatment level tested for

birds (dietary study only), the RQs for acute or chronic effects to birds were not calculated in the

Risk Estimation section of this assessment. Therefore, in order to gain a better understanding of

how the EECs for the application rates for d‐limonene relate to the toxicity data currently

available, a ratio of the EEC/acute endpoint was calculated under the assumption that the

highest level tested is the endpoint value. While this analysis is of limited utility for the high rates

(18.4, 34.6, 55.1 lb a.i./A) because the highest treatment level the animal was exposed to was

lower than the EECs by a large margin for the majority of feed items, it can provide useful

information for the lower rate. At 4.6 lb a.i./A., the EEC of 4816 ppm is lower than the highest

test concentration (5600 ppm) at which no mortality or sublethal effects were observed, thus,

the risk to birds on an acute exposure basis is considered to be low.   
32 

As discussed in the mammal section above, there is uncertainty with regard to the foliar

dissipation half‐life. In order to explore the shorter half‐life of 2‐days, the EECs from TREX with a

2‐day foliar dissipation half‐life were compared to the 5600 ppm endpoint. The risk to birds at

the lowest rate was low. In contrast to using the default half‐life, when using the shorter half‐life,

the 18.4 lb a.i./A rate could also be analyzed because the EECs were below the highest test

concentration in the toxicity test. For the 18.4 lb a.i./A application scenario, the EEC of 4844 ppm

is lower than the highest test concentration at which no mortality or sublethal effects were

observed (5600 ppm), thus, the risk to birds on an acute exposure basis is considered to be low.   

 

Based on the available data, risk is presumed for the highest application scenarios (the 34.6 and

55.1 lb a.i./A rates). While there is uncertainty because the only data available is from a dietary

study (which may underestimate the risk compared to an acute oral study), and a sufficient

number of foliar dissipation values are not available at this time, the risk to birds from the lower

rates of 4.6 and 18.4 lb a.i./A is considered to be low. An acute oral study (tested up to

environmentally relevant EECs or within the physiological limits of the bird) and additional data

for the foliar dissipation half‐life would reduce the uncertainty in this analysis. Additionally, the

risk for birds on a chronic exposure basis is uncertain without data.  

Terrestrial invertebrates 

Due to a lack of toxicity data, at this time the risk to terrestrial invertebrates is presumed given

that d‐limonine is registered as an insecticide.  

Terrestrial Plants  

Two different analyses were used to assess the risk to terrestrial plants. In the screening level

analysis with TerrPlant, there were no RQ exceedances for applications at the 4.6 or 18.4 lb a.i./A

rate. At the 34.6 and 55.1 lb a.i./A rates, there were LOC exceedances (RQs= 1.8 and 2.9,

respectively) for listed monocots.  

Using the Ag Drift analysis, different factors related to the droplet size were incorporated based

on language for reducing spray drift on the Avenger label. For this assessment, the Avenger use

(34.6 lb a.i./A) was assigned to a medium‐coarse droplet and the other assessed rates (Orange

Guard label) were assigned to the default‐fine droplet size. At the 4.6 lb a.i./A rate, the distance

to no longer exceed the LOC was 0‐3 feet for non‐listed species and 3‐23 feet for listed species.

For the higher rates (18.4‐55.1 lb a.i./A), the distance ranged from 3‐19 feet for non‐listed

species and 9‐305 feet for listed species.  

Based on these analyses, there is a risk identified from spray drift to non‐target listed and non‐

listed plants with the exception of non‐listed dicots at the 4.6 lb a.i./A rate. There was one

“minor” plant damage incident reported as well (See Review of Incident data).  

 

   
33 

Review of Incident Data 

Reviews of the Ecological Incident Information System (EIIS) and the Avian Incident Monitoring

System (AIMS)33 were conducted on 9/18/14. There are no reported incidents for d‐limonene in

the EIIS or AIMS databases. In addition to the incidents recorded in EIIS and AIMS, additional

pesticide incidents are reported to the Agency in aggregated incident reports. Ecological

incidents reported in aggregate reports include those categorized as ‘minor fish and wildlife’ (W‐

B), ‘minor plant’ (P‐B), and ‘other non‐target’ (ONT) incidents. ‘Other non‐target’ incidents

include reports of adverse effects to insects and other terrestrial invertebrates. A query of the

aggregate incident report on 9/25/14, found a single incident reported for HOME DEFENSE

INDOOR INSECT KILLER‐RTU (EPA product number: 045987‐000239). The incident was reported

as ‘minor plant’ damage during the time period of 4/1/04 ‐6/30/04. No further information is

available.  

Federally Threatened and Endangered (Listed) Species Concerns 

 

Before completing this Registration Review, the Agency will conduct an ecological risk

assessment to address the Agency’s obligations under both the Endangered Species Act (ESA)

and FIFRA. While the risk assessment supporting this proposed interim Registration Review

decision evaluates risks to species that are not subject to the ESA, EPA is still in the process of

conducting a risk assessment for endangered and threatened (listed) species and their

designated critical habitats for d‐limonene. In this proposed interim decision, therefore, EPA has

not completed effects determinations for listed species associated with the registered uses of d‐

limonene.  

At this time, EPA has not fully developed its risk assessment process for listed species. In

November 2013, the EPA, along with the U.S. Fish & Wildlife Service (USFWS), the National

Marine Fisheries Service (NMFS) (collectively, the Services), and the U.S. Department of

Agriculture (USDA) released a summary of their joint Interim Approaches for assessing risks to

listed species from pesticides. The Interim Approaches were developed jointly by the Agencies in

response to the National Academy of Sciences’ (NAS) recommendations and reflect a common

approach to risk assessment shared by the Agencies as a way of addressing scientific differences

between the EPA and the Services.  The NAS report, available at

http://www.nap.edu/catalog.php?record_id=18344, outlines recommendations on specific

scientific and technical issues related to the development of pesticide risk assessments that EPA

and the Services must conduct in connection with their obligations under the ESA and FIFRA. The

joint Interim Approaches were released prior to a stakeholder workshop held on November 15,

2013. In addition, the EPA presented the joint Interim Approaches at the December 2013

Pesticide Program Dialogue Committee (PPDC) and State‐FIFRA Issues Research and Evaluation

Group (SFIREG) meetings, allowing additional opportunities for stakeholders to comment on the

Interim Approaches. As part of a phased, iterative process for developing the Interim

Approaches, the Agencies will also consider public comments on the Interim Approaches in

connection with the development of upcoming Registration Review decisions.  The details of the

 

33 http://www.abcbirds.org/abcprograms/policy/pesticides/aims/aims/index.cfm 
34 

joint Interim Approaches  are contained in the white paper “Interim Approaches for National‐

Level Pesticide Endangered Species Act Assessments Based on the Recommendations of the

National Academy of Sciences April 2013 Report,” dated November 1, 2013, available at

http://www.epa.gov/espp/2013/nas.html.    

Clean Water Act  

Limonene is not identified as a cause of impairment for any water bodies listed as impaired

under section 303(d) of the Clean Water Act, based on information provided at

http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885.

In addition, no Total Maximum Daily Loads (TMDL) have been developed for limonene, based on

information provided at

http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutan

t_group_name=PESTICIDES. More information on impaired water bodies and TMDLs can be found at

http://www.epa.gov/owow/tmdl/.

Endocrine Disruptor Screening Program  

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse

outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and

chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental,

reproductive, and general or systemic toxicity. These studies include endpoints which may be

susceptible to endocrine influence, including effects on endocrine target organ histopathology,

organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss,

and sex ratios in offspring.  For ecological hazard assessments, EPA evaluates acute tests and

chronic studies that assess growth, developmental and reproductive effects in different

taxonomic groups. As part of its reregistration decision for d‐limonene, EPA reviewed these data

and selected the most sensitive endpoints for relevant risk assessment scenarios from the

existing hazard database. However, as required by FFDCA section 408(p), d‐limonene is subject

to the endocrine screening part of the Endocrine Disruptor Screening Program (EDSP).  

EPA has developed the EDSP to determine whether certain substances (including pesticide active

and other ingredients) may have an effect in humans or wildlife similar to an effect produced by

a “naturally occurring estrogen, or other such endocrine effects as the Administrator may

designate.” The EDSP employs a two‐tiered approach to making the 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.  
35 

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between October

2009 and February 2010, EPA issued test orders/data call‐ins for the first group of 67 chemicals,

which contains 58 pesticide active ingredients and 9 inert ingredients. A second list of chemicals

identified for EDSP screening was published on June 14, 201334 and includes some pesticides

scheduled for registration review and chemicals found in water. Neither of these lists should be

construed as a list of known or likely endocrine disruptors.  

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

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

website.35

 

 

 

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

chemicals. 35 http://www.epa.gov/endo/ 
Appendix 1. Summary of Labeled Uses for d‐Limonene

Crops or Use Site  %AI  Formulation/ 

Equipment 

Max App Rate (lb a.i./A; unless noted)  

Maximum # of  Appl. per Season/Inter‐val (days) 

Maximum lb a.i./A/Season (year) 

Comments 

Commercial/Inst./ Household/

dwelling;Spot treatment, crack & crevice,

surface spray, direct spray

10 Aerosol can NS As needed NS Spray for 10 sec.

Commercial/Inst./ Household

Crack & crevice

Outdoor general spray

Surface treatment

4.0 Aerosol can

0.031 lb

a.i./200 ft2 NS NS

15 oz container/ 200 

0.031 lb a.i./200 ft2

RTU‐Pet Shampoo

5 Liquid

0.429 lb

a.i./gal

0.04 lb

a.i./12 oz

NS /7 NS

Sponge on, dip, sprinkle 78 EC NS NS NS 1.5 oz/1 gal (product) Residential/turfOutdoor general surface spray,

lawnsCrack & crevice spray

1 Aerosol/RTU‐Spray NS

Do not apply

more than 1

time per day/

NS

Aerosol can, 0.0826 l

RTU‐0.009 lb a.i./14fl

Household/ dwellings

Crack & crevice treatment ; indoor

and outdoor general surface spray;

perimeter treatment

5.8 RTU‐Sprayer

NS

Saturate

area

NS NS

8.139 lb/gal

0.47 lb a.i./gal

Household/ Commercial/

InstitutionalFire ant mound crack & crevice

spray; directed spray, mounddrench; perimeter treatment

5.8 Sprayer 0.2265 lb a.i./mound NS NS

1 to 3 (4)

Sprayer ; 0.5 gal/mou

Spray volume per Are

Assuming 40 mounds 
Crops or Use Site  %AI  Formulation/ 

Equipment 

Max App Rate (lb a.i./A; unless noted)  

Maximum # of  Appl. per Season/Inter‐val (days) 

Maximum lb a.i./A/Season (year) 

Comments 

Ornamental plants in greenhouses,nurseries, Christmas tree plantations,and landscapes (residentialcommercial, industrial) 5.8

Pump sprayer

Handheld sprayer

Ground

4.6  6/7 27.6

Rates were expressed aa.i./gal water), or (1:6) 

volumes. “row crops 25

gal/A, tree crops 100‐40

gal /10,000 sq ft, 600 ga

18.4  6/7 110.4

36.8 6/7 220.840.1 6/7 240.6

55.2  6/7 331.2

Void treatment; wood surface

treatment; 95

RTU

Injection eq.

5.19 lb

a.i./100 ft2 As needed NS

1 oz/ft2

0.052 lb a.i./ft2

Soil drench/Soil treatment

(fire ant)

78.2 Pump spray bottle

0.3534 lb/2

gal;

0.0883

lb/0.5 gal

NS NS

Household/outdoor premises Crack

& crevice 10

RTU

Aerosol can

NS NS NS Aerosol can; Spray fo

Commercial/premisesCracks & crevice; general surface 4.0

RTU

Sprayer

0.030 lb

a.i./200 ft2 As needed NS 0.246 lb a.i./gal‐27 ga

Treated strip; clothing treatment;

skin contact 4.0 Wrist band/ Impreg. material NS As needed NS

Borders around driveways, patios,

sidewalks, mature trees and

ornamentals, buildings, residentialgreenhouses, fencerows,flowerbeds

Conc.

(70%)/

RTU

(17.5

%)

Sprayer

1.28‐1.47 lb

a.i./gal

(dilution)

51‐59 lb

a.i./A*

12

Weed post‐

emergence

NS

*Assumed 40 gallons 

did not have a finish s

complete the rate. Ne

on label to reduce un

uncertainty and the u

treatment, this assess

scenarios above to in

use.
Crops or Use Site  %AI  Formulation/ 

Equipment 

Max App Rate (lb a.i./A; unless noted)  

Maximum # of  Appl. per Season/Inter‐val (days) 

Maximum lb a.i./A/Season (year) 

Comments 

Ag. Crops: Brassica veg; citrus;

grapes; herbs; leafy veg; legume

veg; pome fruit; root & tuber

Weed post‐emergence/ burndown

55%

Ground Sprayer‐

Directed/ Hooded

sprayer

Broadcast and Spot

treatment

34.6 

12 (2) NS

Label states do not ex

product per acre per 

a.i./gal * 8.5 gal/A= 3

Household/domestic dwellings

outdoor premises; residential

lawns. 23

RTU

Garden hose‐end

sprayer

0.454 lb

a.i/1000 ft2

(19.79) 12 NS For control of algae a

 
39 

Appendix 2.  Estimation Aerobic Metabolism

Misra and Pavlostathis36 (1997) conducted batch experiments to evaluate biodegradation rates of

several monoterpenes, including limonene, in liquid and soil‐slurry systems, under aerobic conditions.

Biodegradations was demonstrated through the depletion of the monoterpene mass, CO2 production,

and a corresponding increase in biomass. In liquid cultures with no soil, monoterpene degradation

followed a Monod or Michaelis‐Menten type kinetics equation (Rafai and Newell, 1998)37 (eq. 1),   

μ ൌ‐μmax∗ ௌ

௄௦ାௌ            (eq. 1)

  

where μ is the specific growth rate, s (mg/L) is the concentration in solution, t is time (days), μmax is the

maximum reaction rate (mg/L per day), and Ks (mg/L) is the substrate saturation constant (i.e.,

saturation constant at half μmax). In the Monod model, the growth rate is related to the concentration of

a growth limiting substrate through the parameters μmax and Ks (Rifai and Newell, 1998; Okpokwasili and

Nweke38, 2005). Additionally, Monod related the yield coefficient (Yx/s) eq. 2 to the specific rate of

biomass growth (μ) and the specific rate of substrate utilization (q) (eq. 3).

Yx/s = ௗ௫

ௗ௦                                    (eq. 2)

μ = Yx/s/ܺ  .

ௗ௦

ௗ௧

≈ Yx/s*q     (eq. 3)

Further, Rifai and Newell (1998) provided a method to estimate a first‐order decay rate to estimate a

half‐life for input into the fate models. They suggest that high values of Ks (i.e., Ks >>S) the Monod

equation simplifies to eq. 4.

  

   

ௗௌ

ௗ௧  = ‐umax

ௌ

௄௦         (eq. 4)

And that the first‐order decay constant, k, (day‐1

) is estimated from the expression μmax/Ks.

Misra and Pavlostathis (1997) reported in values (Table 2) for ‐μmax 0.022 and 0.024 (h‐1

) and Ks 17 and

32 (mg l

‐1

) for solutions below and above solubility, respectively. These values result in half‐life

estimates of 22.7 and 38.5 days for below and above solubility, respectively.  

 

 

 

 

 

 

 

36 Misra and Pavlostathis. 1997. Appl. Microbiol. Biotechnol. 47:572‐577. 37 Rifai and Newell, 1998. https://info.ngwa.org/GWOL/pdf/982664575.PDF 38 Okpokwasili, G.C. and C.O. Nweke, 2005. Microbial growth and substrate utilization kinetics. African J. Biotech. 5:305‐317.
40 

Appendix 3. SWCC EEC 

Table 1.  SWCC d‐limonene estimated Peak, 96‐hour, 21‐day and 60‐day average concentrations in standard 

farm pond for max rates. 

Pond Peak 4‐day 21‐day 60‐day

Scenario 1‐year in 10‐year concentration (μg/L)

NC Sweet Potato       2390 1640 762 353

FL strawberry 2370 1490 486 198

GA Pecans            2330 1670 663 318

CA lettuce          2010 1540 687 279

FL tomato        1850 1110 525 242

GA Onion W irrig    1680 1130 479 223

FL citrus          1640 864 359 194

PA tomato           1310 935 481 224

TN nursery         1270 1020 556 332

NJ nursery          1260 1140 1050 847

PA apple           1120 792 448 194

CA almond W irrig    1090 695 314 173

PA apple          991 657 403 226

MI beans             986 605 266 139

ME potato           910 696 359 168

MI nursery        872 833 756 633

ND canola            809 470 222 114

OR Xmas Tree         709 456 277 189

FL nursery       697 448 219 177

OR nursery        663 466 303 191

CA nursery        581 390 224 150

CA onion W irrig     558 412 192 102

CA grapes W irrig    541 461 232 113

OR filberts          508 377 254 168

CA citrus W irrig    413 290 158 101

OR filberts         408 318 196 109

OR mint              398 307 226 149

IDN potato W irrig   363 271 198 140

PA turf              345 242 190 131

OR apple           339 258 215 153

ID potato W irrig   275 208 116 83.9

OR apple            221 163 137 71.3

 

 

 

 

 

 

 

 
41 

Appendix 4. Representative Model Outputs 

Surface Water Calculator (SWCC) 

Summary of Water Modeling of d-limonene and the USEPA Standard Pond 

Estimated Environmental Concentrations for d-limonene are presented in Table 

1 for the USEPA standard pond with the NCSweetPotatoSTD field scenario. A 

graphical presentation of the year-to-year peaks is presented in Figure 1. 

These values were generated with the Surface Water Concentration Calculator 

(SWCC Version 1.106). Critical input values for the model are summarized in 

Tables 2 and 3. 

This model estimates that about 1.2% of d-limonene applied to the field 

eventually reaches the water body. The main mechanism of transport from the 

field to the water body is by runoff (51.4% of the total transport), followed 

by erosion (34.5%) and spray drift (14.1%). 

In the water body, pesticide dissipates with an effective water column halflife of 4.2 days. (This value does not include dissipation by transport to 

the benthic region; it includes only processes that result in removal of 

pesticide from the complete system.) The main source of dissipation in the 

water column is volatilization (effective average half-life = 4.3 days) 

followed by metabolism (119 days). 

In the benthic region, pesticide is stable. The vast majority of the 

pesticide in the benthic region (99.29%) is sorbed to sediment rather than in 

the pore water. 

Table 1. Estimated Environmental Concentrations (ppb) for d-limonene. 

Peak (1-in-10 yr) 0.239E+04 

4-day Avg (1-in-10 yr) 0.164E+04 

21-day Avg (1-in-10 

yr) 

762. 

60-day Avg (1-in-10 

yr) 

353. 

365-day Avg (1-in-10 

yr) 

73.0 

Entire Simulation Mean 42.2 

 
42 

Table 2. Summary of Model Inputs for d-limonene. 

Scenario NCSweetPotatoSTD

Cropped Area Fraction 1

Koc (ml/g) 1300

Water Half-Life (days) @ 25 °C 67.1

Benthic Half-Life (days) @ 25 

°C 

0

Photolysis Half-Life (days) @ 

28 °Lat 

0

Hydrolysis Half-Life (days) 0

Soil Half-Life (days) @ 25 °C 33

Foliar Half-Life (days) 0

Molecular Wt 136.23

Vapor Pressure (torr) 2

Solubility (mg/l) 13.8

Table 3. Application Schedule for d-limonene. 

Date (Days 

Since 

Emergence) 

Type Amount (kg/ha) Eff. Drift 

1 Ground 38.75 0.99 0.017 

3 Ground 38.75 .99 .017 

5 Ground 38.75 .99 .017 

7 Ground 38.75 .99 .017 

9 Ground 38.75 .99 .017 

11 Ground 38.75 .99 .017 

13 Ground 38.75 .99 .017 

15 Ground 38.75 .99 .017 

17 Ground 38.75 .99 .017 

19 Ground 38.75 .99 .017 

21 Ground 38.75 .99 .017 

23 Ground 38.75 .99 .017 
43 

Figure 1. Yearly Peak Concentrations 

 
44 

PRZM/EXAMS (PE5) 

Without volatilization 

stored as NJnurse.out 

Chemical: d-limonene 

PRZM environment: NJnurserySTD_V2.txt modified Sunday, 30 September 2007 at 23:05:00 

EXAMS environment: pond298.exv modified Wedday, 15 November 2006 at 13:47:26 

Metfile: w93730.dvf modified Wedday, 3 July 2002 at 10:05:58 

Water segment concentrations (ppb) 

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 

1961 430 413 375 261 208 55.58 

1962 816 641 351 176 157 42.45 

1963 582 560 450 359 266 70.93 

1964 565 412 273 142 104 28.34 

1965 687 505 400 233 168 44.49 

1966 2010 1920 1550 810 584 156 

1967 277 211 157 131 107 30.14 

1968 1650 1600 1420 1040 739 195 

1969 634 605 407 203 144 38.24 

1970 379 309 278 159 111 30.31 

1971 653 489 368 307 217 57.74 

1972 509 379 223 139 106 28.75 

1973 1300 918 377 179 127 34.21 

1974 163 137 117 55.81 45.64 12.95 

1975 536 398 261 137 99.3 26.98 

1976 958 741 560 316 218 58.29 

1977 1250 1220 1110 534 380 100 

1978 1930 1850 1560 1170 848 225 

1979 1650 1220 667 537 395 106 

1980 528 511 465 360 263 72.28 

1981 313 300 267 165 117 32.31 

1982 988 943 661 352 249 65.93 

1983 282 242 164 92.55 72.74 21.59 

1984 600 578 414 238 194 52.56 

1985 375 297 272 159 110 30.61 

1986 1660 1250 552 250 184 52.04 

1987 888 862 754 555 400 108 

1988 852 832 625 328 232 61.58 

1989 243 199 141 78.3 60.21 16.84 

1990 202 151 110 59.36 41.59 12.22 

Sorted results 

Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 

0.032258064516129 2010 1920 1560 1170 848 225 

0.0645161290322581 1930 1850 1550 1040 739 195 

0.0967741935483871 1660 1600 1420 810 584 156 

0.129032258064516 1650 1250 1110 555 400 108 

0.161290322580645 1650 1220 754 537 395 106 

0.193548387096774 1300 1220 667 534 380 100 

0.225806451612903 1250 943 661 360 266 72.28 

0.258064516129032 988 918 625 359 263 70.93 

0.290322580645161 958 862 560 352 249 65.93 

0.32258064516129 888 832 552 328 232 61.58 

0.354838709677419 852 741 465 316 218 58.29 

0.387096774193548 816 641 450 307 217 57.74 

0.419354838709677 687 605 414 261 208 55.58 

0.451612903225806 653 578 407 250 194 52.56 

0.483870967741936 634 560 400 238 184 52.04 

0.516129032258065 600 511 377 233 168 44.49 

0.548387096774194 582 505 375 203 157 42.45 

0.580645161290323 565 489 368 179 144 38.24 

0.612903225806452 536 413 351 176 127 34.21 

0.645161290322581 528 412 278 165 117 32.31 

0.67741935483871 509 398 273 159 111 30.61 

0.709677419354839 430 379 272 159 110 30.31 

0.741935483870968 379 309 267 142 107 30.14 

0.774193548387097 375 300 261 139 106 28.75 

0.806451612903226 313 297 223 137 104 28.34 

0.838709677419355 282 242 164 131 99.3 26.98 

0.870967741935484 277 211 157 92.55 72.74 21.59 

0.903225806451613 243 199 141 78.3 60.21 16.84 
45 

0.935483870967742 202 151 117 59.36 45.64 12.95 

0.967741935483871 163 137 110 55.81 41.59 12.22 

0.1 1659 1565 1389 784.5 565.6 151.2 

 Average of yearly averages: 62.2453333333333 

Inputs generated by pe5.pl - Novemeber 2006 

Data used for this run: 

Output File: NJnurse 

Metfile: w93730.dvf 

PRZM scenario: NJnurserySTD_V2.txt 

EXAMS environment file: pond298.exv 

Chemical Name: d-limonene 

Description Variable Name Value Units Comments 

Molecular weight mwt 136.23 g/mol 

Henry's Law Const. henry 2.6e-2 atm-m^3/mol 

Vapor Pressure vapr 2 torr 

Solubility sol 13.8 mg/L 

Kd Kd mg/L 

Koc Koc 1300 mg/L 

Photolysis half-life kdp 0 days Half-life 

Aerobic Aquatic Metabolism kbacw 67.1 days Halfife 

Anaerobic Aquatic Metabolism kbacs 0 days Halfife 

Aerobic Soil Metabolism asm 33.53 days Halfife 

Hydrolysis: pH 7 0 days Half-life 

Method: CAM 1 integer See PRZM manual 

Incorporation Depth: DEPI cm 

Application Rate: TAPP 38.75 kg/ha 

Application Efficiency: APPEFF 0.99 fraction 

Spray Drift DRFT 0.017 fraction of application rate applied to pond 

Application Date Date 01-01 dd/mm or dd/mmm or dd-mm or dd-mmm 

Interval 1 interval 2 days Set to 0 or delete line for single app. 

app. rate 1 apprate 38.75 kg/ha 

Interval 2 interval 2 days Set to 0 or delete line for single app. 

app. rate 2 apprate 38.75 kg/ha 

Interval 3 interval 2 days Set to 0 or delete line for single app. 

app. rate 3 apprate 38.75 kg/ha 

Interval 4 interval 2 days Set to 0 or delete line for single app. 

app. rate 4 apprate 38.75 kg/ha 

Interval 5 interval 2 days Set to 0 or delete line for single app. 

app. rate 5 apprate 38.75 kg/ha 

Interval 6 interval 2 days Set to 0 or delete line for single app. 

app. rate 6 apprate 38.75 kg/ha 

Interval 7 interval 2 days Set to 0 or delete line for single app. 

app. rate 7 apprate 38.75 kg/ha 

Interval 8 interval 2 days Set to 0 or delete line for single app. 

app. rate 8 apprate 38.75 kg/ha 

Interval 9 interval 2 days Set to 0 or delete line for single app. 

app. rate 9 apprate 38.75 kg/ha 

Interval 10 interval 2 days Set to 0 or delete line for single app. 

app. rate 10 apprate 38.75 kg/ha 

Interval 11 interval 2 days Set to 0 or delete line for single app. 

app. rate 11 apprate 38.75 kg/ha 

Record 17: FILTRA 

IPSCND 1 

UPTKF 

Record 18: PLVKRT 

PLDKRT 

FEXTRC 0.5 

Flag for Index Res. Run IR EPA Pond 

Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run) 

PRZM/EXAMS (PE5) 

With Volatilization 

Diffusion In Air Coefficient DAIR = 4300 cm2/day 

Enthalpy of Vaporizaton = 10.48 kcal/mole 

stored as NJnurseV.out 

Chemical: d-limonene 

PRZM environment: NJnurserySTD_V2.txt modified Sunday, 30 September 2007 at 23:05:00 

EXAMS environment: pond298.exv modified Wedday, 15 November 2006 at 13:47:26 

Metfile: w93730.dvf modified Wedday, 3 July 2002 at 10:05:58 

Water segment concentrations (ppb) 
46 

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 

1961 325 311 272 147 102 26.56 

1962 127 110 100 49.06 33.74 8.762 

1963 310 296 265 206 148 38.9 

1964 106 84.75 76.44 35.12 24.1 6.27 

1965 309 297 255 129 88.58 23.06 

1966 313 300 267 209 150 39.45 

1967 129 112 97.4 59.61 43.14 11.36 

1968 320 306 274 214 152 39.79 

1969 316 302 257 124 84.67 21.89 

1970 309 295 255 128 88.41 22.98 

1971 315 302 262 138 94.86 24.73 

1972 125 108 94.67 46.4 31.76 8.227 

1973 120 103 90.31 43.45 29.72 7.693 

1974 123 106 93.01 44.55 30.37 7.842 

1975 117 98.19 87.38 41.25 28.23 7.309 

1976 317 304 264 137 94.51 24.67 

1977 319 305 265 137 93.87 24.44 

1978 339 327 294 228 164 43.44 

1979 138 114 87.84 51.58 36.9 9.693 

1980 314 300 269 210 150 39.7 

1981 311 297 257 137 94.57 24.67 

1982 324 310 265 141 97.49 25.52 

1983 130 112 98.22 48.6 33.4 8.721 

1984 309 297 256 133 91.87 23.94 

1985 309 295 255 135 92.71 24.18 

1986 124 107 94.16 47.12 32.5 8.508 

1987 318 305 272 211 152 40.09 

1988 315 302 260 137 94.79 24.7 

1989 129 112 97.92 48.25 33.25 8.687 

1990 120 103 90.7 43.72 30.03 7.813 

Sorted results 

Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 

0.032258064516129 339 327 294 228 164 43.44 

0.0645161290322581 325 311 274 214 152 40.09 

0.0967741935483871 324 310 272 211 152 39.79 

0.129032258064516 320 306 272 210 150 39.7 

0.161290322580645 319 305 269 209 150 39.45 

0.193548387096774 318 305 267 206 148 38.9 

0.225806451612903 317 304 265 147 102 26.56 

0.258064516129032 316 302 265 141 97.49 25.52 

0.290322580645161 315 302 265 138 94.86 24.73 

0.32258064516129 315 302 264 137 94.79 24.7 

0.354838709677419 314 300 262 137 94.57 24.67 

0.387096774193548 313 300 260 137 94.51 24.67 

0.419354838709677 311 297 257 137 93.87 24.44 

0.451612903225806 310 297 257 135 92.71 24.18 

0.483870967741936 309 297 256 133 91.87 23.94 

0.516129032258065 309 296 255 129 88.58 23.06 

0.548387096774194 309 295 255 128 88.41 22.98 

0.580645161290323 309 295 255 124 84.67 21.89 

0.612903225806452 138 114 100 59.61 43.14 11.36 

0.645161290322581 130 112 98.22 51.58 36.9 9.693 

0.67741935483871 129 112 97.92 49.06 33.74 8.762 

0.709677419354839 129 112 97.4 48.6 33.4 8.721 

0.741935483870968 127 110 94.67 48.25 33.25 8.687 

0.774193548387097 125 108 94.16 47.12 32.5 8.508 

0.806451612903226 124 107 93.01 46.4 31.76 8.227 

0.838709677419355 123 106 90.7 44.55 30.37 7.842 

0.870967741935484 120 103 90.31 43.72 30.03 7.813 

0.903225806451613 120 103 87.84 43.45 29.72 7.693 

0.935483870967742 117 98.19 87.38 41.25 28.23 7.309 

0.967741935483871 106 84.75 76.44 35.12 24.1 6.27 

0.1 323.6 309.6 272 210.9 151.8 39.781 

 Average of yearly averages: 21.1198333333333 

Inputs generated by pe5.pl - Novemeber 2006 
47 

Data used for this run: 

Output File: NJnurseV 

Metfile: w93730.dvf 

PRZM scenario: NJnurserySTD_V2.txt 

EXAMS environment file: pond298.exv 

Chemical Name: d-limonene 

Description Variable Name Value Units Comments 

Molecular weight mwt 136.23 g/mol 

Henry's Law Const. henry 2.6e-2 atm-m^3/mol 

Vapor Pressure vapr 2 torr 

Solubility sol 13.8 mg/L 

Kd Kd mg/L 

Koc Koc 1300 mg/L 

Photolysis half-life kdp 0 days Half-life 

Aerobic Aquatic Metabolism kbacw 67.1 days Halfife 

Anaerobic Aquatic Metabolism kbacs 0 days Halfife 

Aerobic Soil Metabolism asm 33.53 days Halfife 

Hydrolysis: pH 7 0 days Half-life 

Method: CAM 1 integer See PRZM manual 

Incorporation Depth: DEPI cm 

Application Rate: TAPP 38.75 kg/ha 

Application Efficiency: APPEFF 0.99 fraction 

Spray Drift DRFT 0.017 fraction of application rate applied to pond 

Application Date Date 01-01 dd/mm or dd/mmm or dd-mm or dd-mmm 

Interval 1 interval 2 days Set to 0 or delete line for single app. 

app. rate 1 apprate 38.75 kg/ha 

Interval 2 interval 2 days Set to 0 or delete line for single app. 

app. rate 2 apprate 38.75 kg/ha 

Interval 3 interval 2 days Set to 0 or delete line for single app. 

app. rate 3 apprate 38.75 kg/ha 

Interval 4 interval 2 days Set to 0 or delete line for single app. 

app. rate 4 apprate 38.75 kg/ha 

Interval 5 interval 2 days Set to 0 or delete line for single app. 

app. rate 5 apprate 38.75 kg/ha 

Interval 6 interval 2 days Set to 0 or delete line for single app. 

app. rate 6 apprate 38.75 kg/ha 

Interval 7 interval 2 days Set to 0 or delete line for single app. 

app. rate 7 apprate 38.75 kg/ha 

Interval 8 interval 2 days Set to 0 or delete line for single app. 

app. rate 8 apprate 38.75 kg/ha 

Interval 9 interval 2 days Set to 0 or delete line for single app. 

app. rate 9 apprate 38.75 kg/ha 

Interval 10 interval 2 days Set to 0 or delete line for single app. 

app. rate 10 apprate 38.75 kg/ha 

Interval 11 interval 2 days Set to 0 or delete line for single app. 

app. rate 11 apprate 38.75 kg/ha 

Record 17: FILTRA 

IPSCND 1 

UPTKF 

Record 18: PLVKRT 

PLDKRT 

FEXTRC 0.5 

Flag for Index Res. Run IR EPA Pond 

Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run) 
48 

Appendix 5. TREX Model Sample Input/Output 

INPUT 

Table 1.  Input‐ Orange Guard (4.6 lb a.i./A)   

 

Chemical Name:  d‐limonene   

      Use  0   

      Formulation  Orange Guard    

Application Rate  4.6  lb a.i./acre   

Half‐life  35  days    

Application Interval  7  days   

Maximum # Apps./Year  6    

Length of Simulation  1  year   

Variable application rates?  no      

       

Endpoints 

Avian 

Bobwhite quail  LD50 (mg/kg‐bw)  0.00 

Bobwhite quail  LC50 (mg/kg‐diet)  5600.00 

Mallard duck  NOAEL(mg/kg‐bw)  0.00 

Bobwhite quail  NOAEC (mg/kg‐diet)  0.00 

           

Mammals 

LD50 (mg/kg‐bw)  4400.00 

LC50 (mg/kg‐diet)  0.00 

NOAEL (mg/kg‐bw)  250.00 

NOAEC (mg/kg‐diet)  5000.00 

Output

Table 2.  Upper Bound Kenaga, Subacute Avian Dietary Based Risk Quotients‐ Orange Guard (4.6 lb a.i./A)                        

(For Characterization‐non‐definitive endpoint) 

LC50 

EECs and RQs 

Short Grass  Tall Grass  Broadleaf Plants  Fruits/Pods/ 

Seeds  Arthropods 

EEC  RQ  EEC  RQ  EEC  RQ  EEC  RQ  EEC  RQ 

5600 4816.21 0.86 2207.43 0.39 2709.12 0.48 301.01 0.05 1886.35 0.34

 

 
49 

 

Table 3. Upper Bound Kenaga, Acute  Mammalian Dose‐Based  Risk Quotients ‐ Orange Guard (4.6 lb a.i./A)   

Size 

Class 

(grams) 

Adjusted 

LD50 

EECs and RQs 

Short Grass  Tall Grass  Broadleaf 

Plants 

Fruits/Pods/ 

Seeds  Arthropods  Granivore 

EEC  RQ  EEC RQ EEC RQ EEC RQ  EEC  RQ EEC RQ

15 9670 4592 0.47 2105 0.22 2583 0.27 287 0.03 1798 0.19 64 0.01

35 7824 3174 0.41 1455 0.19 1785 0.23 198 0.03 1243 0.16 44 0.01

1000 3384 736 0.22 337 0.10 414 0.12 46 0.01 288 0.09 10 0.00

 

Table 4.  Upper Bound Kenaga, Chronic Mammalian Dose‐Based Risk Quotients‐ Orange Guard (4.6 lb a.i./A)   

Size 

Class 

(g) 

Adjusted 

NOAEL 

EECs and RQs 

Short Grass  Tall Grass  Broadleaf 

Plants 

Fruits/Pods/ 

Seeds  Arthropods  Granivore 

EEC  RQ  EEC  RQ  EEC  RQ  EEC  RQ  EEC  RQ  EEC  RQ 

15 549.5 4592 8.36 2105 3.83 2583 4.70 287 0.52 1798 3.27 64 0.12

35 444.6 3174 7.14 1455 3.27 1785 4.02 198 0.45 1243 2.80 44 0.10

1000 192.3 736 3.83 337 1.75 414 2.15 46 0.24 288 1.50 10 0.05

Input 

Table 5.  Input‐ Orange Guard (4.6 lb a.i./A with 2 day foliar dissipation half‐life)   

Chemical Name:  d‐limonene 

Use  0 

Formulation  Orange Guard 

Application Rate  4.6  lb a.i./acre 

Half‐life  2  days 

Application Interval  7  days 

Maximum # Apps./Year  6 

Length of Simulation  1  year 

Variable application rates?  no   

 

Endpoints 

Avian 

Bobwhite quail  LD50 (mg/kg‐bw) 0.00

Bobwhite quail  LC50 (mg/kg‐diet)  5600.00 

Mallard duck  NOAEL(mg/kg‐bw) 0.00

Bobwhite quail  NOAEC (mg/kg‐diet)  0.00 

   

 

Mammals 

LD50 (mg/kg‐bw) 4400.00

LC50 (mg/kg‐diet) 0.00

NOAEL (mg/kg‐bw) 250.00

NOAEC (mg/kg‐diet) 5000.00
50 

Table 6.  Upper Bound Kenaga, Subacute Avian Dietary Based Risk Quotients‐ 

(4.6 lb a.i./A‐2‐day for characterization )   

LC50 

EECs and RQs 

Short Grass  Tall Grass  Broadleaf Plants  Fruits/Pods/Seeds  Arthropods 

EEC  RQ  EEC  RQ  EEC  RQ  EEC  RQ  EEC  RQ 

5600 1211.04 0.22 555.06 0.10 681.21 0.12 75.69 0.01 474.32 0.08

 

Table 7. Upper Bound Kenaga, Acute  Mammalian Dose‐Based  Risk Quotients  

(4.6 lb a.i./A‐2‐day for characterization )   

Size 

Class 

(grams) 

Adj. 

LD50 

EECs and RQs 

Short Grass  Tall Grass  Broadleaf 

Plants 

Fruits/Pods/ 

Seeds  Arthropods  Granivore 

EEC  RQ  EEC RQ EEC RQ EEC RQ EEC  RQ EEC RQ

15 9670 1155 0.12 529 0.05 649 0.07 72 0.01 452 0.05 16 0.002

35 7824 798 0.10 366 0.05 449 0.06 50 0.01 313 0.04 11 0.001

1000 3384 185 0.05 85 0.03 104 0.03 12 0.00 72 0.02 3 0.001

 

 

Table 8.  Upper Bound Kenaga, Chronic Mammalian Dose‐Based Risk Quotients   

(4.6 lb a.i./A‐2‐day for characterization )   

Size 

Class 

(grams) 

Adjusted 

NOAEL 

EECs and RQs 

Short Grass  Tall Grass  Broadleaf 

Plants 

Fruits/Pods/

Seeds  Arthropods  Granivore 

EEC  RQ  EEC  RQ  EEC  RQ  EEC  RQ  EEC  RQ  EEC  RQ 

15 549 1155 2.10 529 0.96 649 1.18 72 0.13 452 0.82 16 0.03

35 445 798 1.80 366 0.82 449 1.01 50 0.11 313 0.70 11 0.02

1000 192 185 0.96 85 0.44 104 0.54 12 0.06 72 0.38 3 0.01

 
51 

Appendix 6.  Terr Plant Model Input/output

Table 1. Chemical Identity. 

Chemical Name  Limonene 

Use  Christmas tree plantation 

Application Method  Ground 

Application Form  Spray 

Solubility in Water 

(ppm)  13 

 

Table 2. Input parameters used to derive EECs. 

Input Parameter  Symbol  Value  Units 

Application Rate A 55.2  Lb/A 

Incorporation I 1  none

Runoff Fraction R 0.02  none

Drift Fraction D 0.01  none

 

Table 3. EECs for Limonene.  Units in lb /A. 

Description     EEC 

Runoff to dry areas (A/I)*R 1.104

Runoff to semi‐aquatic areas (A/I)*R*10 11.04

Spray drift  A*D  0.552 

Total for dry areas  ((A/I)*R)+(A*D)  1.656 

Total for semi‐aquatic areas  ((A/I)*R*10)+(A*D)  11.592 

 

Table 4. Plant survival and growth data used for RQ derivation. Units are in lb /A. 

   Seedling Emergence  Vegetative Vigor 

Plant type  EC25  NOAEC   EC25  NOAEC  

Monocot x  x  2.83  0.19 

Dicot x  x  7.09  1.31 

 

Table 5. RQ values for plants in dry and semi‐aquatic areas exposed to Limonene through runoff and/or 

spray drift.* 

Plant Type  Listed Status  Spray Drift   

Monocot non‐listed 0.20    

Monocot listed 2.91    

Dicot non‐listed <0.1    

Dicot listed   0.42    
52 

Table 6. Chemical Identity.    

Chemical Name  Limonene    

Use  Variety of Ag Crops‐Burndown    

Application Method  Ground    

Application Form  Spray     

Solubility in Water 

(ppm)  13    

              

Table 7. Input parameters used to derive EECs.    

Input Parameter  Symbol  Value  Units    

Application Rate A 34.6  lb/A    

Incorporation I 1  none   

Runoff Fraction R 0.02  none   

Drift Fraction D 0.01  none   

              

Table 8. EECs for Limonene.  Units in lb/A.    

Description  Equation  EEC    

Runoff to dry areas (A/I)*R 0.692   

Runoff to semi‐aquatic areas (A/I)*R*10 6.92   

Spray drift  A*D  0.346    

Total for dry areas  ((A/I)*R)+(A*D)  1.038    

Total for semi‐aquatic areas  ((A/I)*R*10)+(A*D)  7.266    

              

Table 9. Plant survival and growth data used for RQ derivation. Units are in lb/A. 

   Seedling Emergence  Vegetative Vigor 

Plant type  EC25  NOAEC   EC25  NOAEC  

Monocot x  x  2.83  0.19 

Dicot x  x  7.09  1.31 

              

Table 10. RQ values for plants in dry and semi‐aquatic areas exposed to Limonene through runoff and/or 

spray drift.* 

Plant Type  Listed Status  Dry   Semi‐Aquatic  Spray Drift 

Monocot non‐listed #VALUE! #VALUE! 0.12

Monocot listed #VALUE! #VALUE! 1.82

Dicot non‐listed #VALUE! #VALUE! <0.1

Dicot listed   #VALUE! #VALUE! 0.26

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.

 
53 

Table 11. Chemical Identity.    

Chemical Name  Limonene    

Use  Vine Crops    

Application Method  Ground    

Application Form  Spray     

Solubility in Water 

(ppm)  13    

              

Table 12. Input parameters used to derive EECs.    

Input Parameter  Symbol  Value  Units    

Application Rate A 18.4  lb/A    

Incorporation I 1  none   

Runoff Fraction R 0.02  none   

Drift Fraction D 0.01  none   

              

Table 13. EECs for Limonene.  Units in lb/A.    

Description  Equation  EEC    

Runoff to dry areas (A/I)*R 0.368   

Runoff to semi‐aquatic areas (A/I)*R*10 3.68   

Spray drift  A*D  0.184    

Total for dry areas  ((A/I)*R)+(A*D)  0.552    

Total for semi‐aquatic areas  ((A/I)*R*10)+(A*D)  3.864    

              

Table 14. Plant survival and growth data used for RQ derivation. Units are in lb/A. 

   Seedling Emergence  Vegetative Vigor 

Plant type  EC25  NOAEC   EC25  NOAEC  

Monocot x  x  2.83  0.19 

Dicot x  x  7.09  1.31 

              

Table 15. RQ values for plants in dry and semi‐aquatic areas exposed to Limonene through runoff and/or 

spray drift.* 

Plant Type  Listed Status  Dry   Semi‐Aquatic  Spray Drift 

Monocot non‐listed #VALUE! #VALUE! <0.1

Monocot listed #VALUE! #VALUE! 0.97

Dicot non‐listed #VALUE! #VALUE! <0.1

Dicot listed   #VALUE! #VALUE! 0.14

 

 
54 

Appendix 7. Sample Input/output for Ag Drift Analysis  

(Examples entered for listed Monocots) 

 

Table 1.  Avenger Label‐Medium‐Course Droplet (34.6 lb a.i./A) 

Table 2. Orange Guard Label‐ Fine to Very Fine Droplet (4.6 lb a.i./A)
55 

Table 3. Orange Guard Label‐ Fine to Very Fine Droplet (18.4 lb a.i./A)

Table 4. Orange Guard Label‐ Fine to Very Fine Droplet (55.2 lb a.i./A)
56 

Appendix 8.  References

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Range (283.15 to 353.15) K and Vapor Pressure of α‐Pinene, d‐Limonene, (±)‐Linalool, and Citral Over the

Pressure Range of 1.0 kPa Atmospheric Pressure. J. Chem. Eng. Data. 54:1087‐1090.

Copolovici, L.O. and U. Niinemets. 2005. Temperature dependancies of Henry’s Law constants and

octanol/water partition coefficients for key plant volatile monoterpenoids. Chemosphere 61:1390‐1400.

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soil in a Sitka spruce forest. Atmospheric Environment. 35:4081‐4087.

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http://www.inchem.org/documents/cicads/cicads/cicad05.htm

Leff, J.W. and N. Fierer. 2008. Volatile organic compound (VOC) emissions from soil and litter samples.

Soil Biology & Chemistry. 40:1629‐1636.

Li, J., E.M. Perdue, S.G. Pavlostathis, and R. Araujo. 1998.  Physicochemical Properties of Selected

Monoterpenes. Environmental International. 24:353‐358.

Massaldi, H.A. and C.J. King, 1973. Simple Technique to Determine Solubilities of Sparingly Soluble

Organics: Solubility and Activity Coefficients of d‐limonene, n‐butylbenzene, and n‐hexyl acetate in water

and sucrose.  J. Chem. Eng. Data. 18:393‐397.  

Miller, D.J. and S.B. Hawthorne. 2000. Solubility of Liquid Flavor and Fragrance Compounds in Subcritical

(Hot/Liquid) Water from 298 K to 473 K. J. Chem. Eng. Data. 45:315‐318.

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Ground Water Association, Westerville, OH.

   
57 

Rifai and Newell, 1998.  https://info.ngwa.org/GWOL/pdf/982664575.PDF

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