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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460 

OFFICE OF 

PREVENTION, PESTICIDES 

AND TOXIC SUBSTANCES 

MEMORANDUM 

DATE: 25 FEBRUARY 2008 

SUBJECT: d-Limonene Occupational Exposure/Risk Assessment for Proposed New 

 Uses of d-Limonene on Tree, Nut, Vine, Berry Crops and Non-Crop 

 Areas. 

 PC Code: 079701 DP Code: 348549 

FROM: Mark I. Dow, Ph.D., Biologist 

 Alternate Risk Integration Assessment Team (ARIA) 

 Risk Integration Minor Use & Emergency Response Branch (RIMUERB) 

 Registration Division (RD) 7505P 

THROUGH: John C. Redden, ARIA Team Leader 

 RIMUERB/RD 7505P 

TO: Dana Vogel, Branch Chief 

 Registration Action Branch 1 (RAB1) 

 Health Effects Division 7509P 

 

INTRODUCTION 

Under provisions in Section 3 of the Federal Insecticide, Fungicide and Rodenticide Act 

(FIFRA), as amended, Cutting Edge Formulations, Inc. has requested registration of the 

herbicide d-limonene. According to the draft label it is intended for use around “tree, 

vine and berry crops (including, but not limited to: small fruits and berries, citrus fruits, 

pome fruits, stone fruits, subtropical fruits, tree nuts, olives, grapes, kiwis and hops)....” 

The proposed product, GreenMatch,TM “may be applied between rows, on berms and for 

general weed control through initial fruit set and after the last harvest.” 

Also according to the draft label, d-limonene is requested for use on “Non-Crop Areas” 

which includes “borders, driveways, sidewalks, around mature landscaping trees, shrubs, 

foliage and ornamentals, around buildings, in greenhouses and nurseries, and around 

flower beds.” 
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This memorandum serves as the ARIA/RD's assessment of exposure and risk to 

occupational pesticide handlers (mixers, loaders, applicators) and to agricultural workers. 

It should be noted that the risk assessment techniques used in this document are those that 

have been developed and refined by the Health Effects Division (HED)/Office of 

Pesticide Programs' Science Policy Council for Exposure (ExpoSAC). Therefore, the 

risk assessment methods are the same as those used by HED and are HED standard 

operating procedure (SOP). 

USE PATTERN SUMMARY 

The use pattern summary is taken from: “GreenMatch Label, Version 1C, December 

2007.” The product requested for registration is GreenMatchTM Organic Burndown 

Herbicide. GreenMatchTM (GM) is intended for the control of grasses and broadleaf 

weeds (annual and perennial) in crop and non-crop areas. 

GM is a liquid formulation which contains 4.1 lb active ingredient (ai) d-limonene per 

gallon (55 % ai/gallon). Rates of application vary; for “small weeds” the rate is 14 % (14 

gal GM/100 gal spray), for “larger weeds” the rate is 18 % (18 gal GM/100 gal spray) 

and for “hard to control weeds” (such as ivy or hard to control perennials) the rate is 

25 % (25 gal GM/100 gal spray). The label states: “A minimum spray volume of 60 

gallons per acre is recommended.” 

 For the highest rate of application: 25 gal GM * 4.1 lb ai/gal = 102.5 lb ai/100 gal 

 finish spray or 1.025 lb ai/gal finish spray. 

 At a minimum spray volume of 60 gallons per acre: 1.025 lb ai/gal finish spray * 

 60 gal finish spray/A = 61.5 lb ai/A 

There is a maximum of 15 gallons GM per acre (15 gal/A * 4.1 lb ai/gal = 61.5 lb ai/A). 

There is a maximum of 4 applications per year (246 lb ai/A/yr). 

GM may not be applied through any type of irrigation system and may not be applied 

aerially. The label also states: “Do not use mist blowers or any other application 

techniques which may result in drift on to desirable vegetation. “ “Do not allow spray 

solution to drip, splash or drift on to desirable vegetation; small amounts can cause severe 

damage to crops.” “Avoid contact of herbicide solution, spray drift or mist with foliage, 

green bark of trunk or branches, fruit or other parts of tees [sic], canes and vines. 

The label directs: “Spray until thoroughly wet.” Because the undersides of weed leaves 

may be more susceptible, side spraying is recommended. Hooded sprayers are 

recommended as are low ground speeds and low spray pressures. 

Applicators and other handlers are required to wear personal protective equipment (PPE) 

consisting of a long-sleeved shirt, long pants, shoes plus socks and protective eyewear. 

The draft label lists a 4 hour restricted entry interval (REI). 
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See Table 1.0 for a summary of the proposed use pattern. 

Table 1.0 Summary of Proposed Use Pattern for d-limonene on Non-Crop Areas 

Formulation GreenMatchTM Organic Burndown Herbicide; 4.1 lb ai/gallon 

liquid; 55.0 % ai; EPA File Symbol 82052-A 

Sites/Crops tree, vine and berry crops (including, but not limited to: small fruits and 

berries, citrus fruits, pome fruits, stone fruits, subtropical fruits, tree nuts, 

olives, grapes, kiwis and hops); 

Non-Crop Areas which includes borders, driveways, sidewalks, around 

mature landscaping trees, shrubs, foliage and ornamentals, around 

buildings, in greenhouses and nurseries, and around flower beds. 

Pest Annual and perennial weeds including grasses and 

broadleaves 

Method of Applic. Ground-boom, low pressure hand wand; hand held pump up 

sprayer; backpack sprayer 

Max. Applic. Rate 15 gallons GM/A (61.5 lbs ai/A) 

Max. No. Applications 4/year 

Applic. Interval Not stated 

Preharvest Interval not applicable for non crop areas 

Restricted Entry Interval 4 hours listed on the label 

Manufacturer Cutting Edge Formulations, Inc. 

OCCUPATIONAL PESTICIDE HANDLER EXPOSURE 

Based upon the proposed use patterns, ARIA/RD believes the most likely methods of 

application will be by ground-boom spray machinery, low pressure hand-wand sprayer, 

backpack sprayer and hand-held pump-up sprayer. ARIA/RD further believes that for 

the proposed new uses, the most highly exposed occupational pesticide handlers will be 

mixer/loaders using open-pour loading of liquid formulations, applicators using opencab, ground-boom sprayers, mixer/loader/applicators using low-pressure hand-wand 

sprayers and backpack sprayers. 

It is possible that some handlers might use hand-held pump-up sprayers. By comparison, 

the volume of spray material handled per day would be much smaller for hand-held 

pump-up sprayers than for the other methods assessed. Exposure and risk from the use of 

hand-held, pump-up sprayers is not expected to be greater than what is estimated for the 

methods assessed. 

Exposure durations are expected to be short-term duration (1-30 days). More than 1 

short-term exposures may occur. However, since treatment blocks are generally expected 

to be comparatively small, intermediate-term (1-6 months) exposures are not expected, 

even for commercial applicators. 

Particularly for ground applications, private (i.e., grower) applicators may perform all 

functions, that is, mix, load and apply the material. The HED ExpoSAC procedure is 
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such that although the same individual may perform all those tasks, they shall be assessed 

separately. The available exposure data for combined mixer/loader/applicator scenarios 

are limited in comparison to the monitoring of these two activities separately. These 

exposure scenarios are outlined in the Pesticide Handler Exposure Database (PHED) 

Surrogate Exposure Guide (August 1998). HED has adopted a methodology to present 

the exposure and risk estimates separately for the job functions in some scenarios and to 

present them as combined in other cases. Most exposure scenarios for hand-held 

equipment (such as hand wands, backpack sprayers, and push-type granular spreaders) 

are assessed as a combined job function. With these types of hand held operations, all 

handling activities are assumed to be conducted by the same individual. The available 

monitoring data support this and HED presents them in this way. Conversely, for 

equipment types such as fixed-wing aircraft, groundboom tractors, or air-blast sprayers, 

the applicator exposures are assessed and presented separately from those of the mixers 

and loaders. By separating the job functions, HED determines the most appropriate 

levels of personal protective equipment (PPE) for each aspect of the job without requiring 

an applicator to wear unnecessary PPE that might be required for a mixer/loader (e.g.,

chemical resistant gloves may only be necessary during the pouring of a liquid 

formulation). 

No chemical specific data were available with which to assess potential exposure to 

pesticide handlers. The estimates of exposure to pesticide handlers are based, in part, 

upon surrogate study data available in the PHED (v. 1.1, 1998). They are also based 

upon study data from the Outdoor Residential Exposure Taskforce (ORETF). 

For pesticide handlers, it is HED standard practice to present estimates of dermal 

exposure for “baseline” that is, for workers wearing a single layer of work clothing 

consisting of a long sleeved shirt, long pants, shoes plus socks and no protective gloves 

as well as for “baseline” and the use of protective gloves or other PPE as might be 

necessary. Label required PPE was discussed earlier. 

The toxicological factors used for risk assessment purposes are taken from: “Exposure 

and Risk Assessment on Lower Risk Pesticide Chemicals - - D-Limonene” prepared by 

the Special Review and Reregistration Division, Office of Pesticide Programs, U.S. EPA 

(24 JAN 2005). 

In the RED document, the Agency determined that for short-term duration (1-30 days) 

dermal and inhalation exposures the Lowest Observable Adverse Effect Level (LOAEL) 

of 400.0 mg ai/kg bw/day should be used to calculate risk. The toxic effects observed 

were liver effects (increased enzymes and liver weights) seen in a 30-day rat gavage 

study. Since the toxicological endpoint is a LOAEL (not a No Observable Adverse 

Effect Level), an additional 3X uncertainty must be applied. Therefore, a Margin of 

Exposure of at least 300 is necessary to protect occupational pesticide handlers from 

short-term exposures to d-limonene as described by the product label. 

However, upon reconsideration of the toxicological data, the RAB1 toxicology team 

notes that the chronic RfD is slightly higher (i.e., more conservative) than the short-term 
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exposure based on the same effect, the cRfD is considered protective of all exposure 

scenarios. Therefore, in this assessment, the RAB1 toxicology team recommends 

using the NOAEL of 160 mg ai/kg bw/day to assess short-term duration inhalation 

and dermal exposures with a MOE of 100 (P.V. Shah, personal communication, 

February 2008). Since a NOAEL is used for risk calculations, a Margin of Exposure ≥

100 is adequate to protect occupational pesticide handlers. A body weight of 70 kg is 

used to calculate exposures to occupational pesticide handlers. See Table 2.0 for a 

summary of estimated exposures and risk to occupational pesticide handlers. 

Table 2.0 Estimated Handler Exposure and Risk from the Proposed Uses of d-Limonene 

Unit Exposure1

mg a.i./lb handled

Applic. 

Rate2

Units 

Treated3

Per Day 

Average Daily 

Dose4

mg a.i./kg bw/day

NOAEL5

mg a.i./kg 

bw/day 

MOE6 

SHORT-TERM

Mixer/Loader - Liquid - Open-pour

Dermal: 

SLNoGlove 2.9 

SLWGloves 0.023 

Inhal 0.0012 

61.5 lb 

ai/A 

40 A/day SLNoGlove 101.9 

SLWGlove 0.8 

Inhal 0.042 

160 

SLNoGlove 

1.6 

SLWGlove 

190 

Applicator - Ground-boom - Open Cab

Dermal: 

SLNoGlove 0.014 

SLWGloves 0.014 

Inhal 0.00074 

61.5 lb 

ai/A 

40 A/day SLNoGlove 0.49 

SLWGlove 0.49 

Inhal 0.026 

160 

SLNoGlove 

310 

SLWGlove 

310 

Mixer/Loader/Applicator Low-Pressure Hand-Wand SprayerLiquid Open Pour 

Dermal: 

SLNoGlove 100.00 

SLWGloves 0.43 

Inhal 0.03 

1.02 lb 

ai/gal 

40 

gal/day 

(41 lb 

ai/day) 

SLNoGlove 58.6 

SLWGloves 0.25 

Inhal 0.018 

160 

SLNoGlove 

2.7 

SLWGloves 

597 

Mixer/Loader/Applicator/Backpack Sprayer 

Dermal: 

SLNoGlove no data 

SLWGloves 2.5 

Inhal 0.03 

1.02 lb 

ai/gal 

40 

gal/day 

(41 lb 

ai/day) 

SLNoGlove no data 

SLWGloves 1.46 

Inhal 0.018 

160 

SLNoGlove 

no data 

SLWGloves 

108 

1. Unit Exposures are taken from “PHED SURROGATE EXPOSURE GUIDE”, Estimates of Worker Exposure from The Pesticide 

Handler Exposure Database Version 1.1, August 1998. Dermal: SLNoGlove = Single layer work clothing (long pants, long-sleeved

shirt, shoes plus socks) No gloves; SLWGloves = single layer work clothing WITH the use of protective gloves; Inhal. = Inhalation. 

Units = mg a.i./pound of active ingredient handled 

2. Applic. Rate. = Taken from draft GreenMatch label 

3. Units Treated are taken from “Standard Values for Daily Acres Treated in Agriculture”; SOP No. 9.1. ExpoSAC; Revised 5 July 

2000; * Units Treated for hand held pump up sprayer adapted from ExpoSAC SOP No. 12 Revised 22 FEB 01, Recommended 

Revisions to the Standard Operating Procedures (SOPs) for Residential Exposure Assessments. 

4. Average Daily Dose = Unit Exposure * Applic. Rate * Units Treated * absorption factor (100 % absorption via dermal and 

inhalation) ÷ Body Weight (70 kg). 

5. NOAEL = No Observable Adverse Effect Level 160 mg a.i./kg bw/day for short-term dermal and inhalation 

6. MOE = Margin of Exposure = NOAEL ÷ ADD. 
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A MOE of 100 is adequate to protect occupational pesticide handlers from short-term 

exposures to d-limonene. Except for mixer/loader/applicators using backpack sprayers, 

all MOEs are > 100, provided handlers wear protective gloves which are NOT listed 

on the label as PPE. 

 

POST-APPLICATION EXPOSURE TO AGRICULTURAL WORKERS 

It is possible for agricultural workers to have post-application exposures to pesticide 

residues during the course of typical agricultural activities. In this case and for these use 

patterns, post-application exposure is expected to be negligible. Sprays should not 

contact any crop areas (i.e. in a greenhouse or around ornamentals). Contact with treated 

foliage is not expected. Scouting for pesticide efficacy does not require contact with 

treated areas. Walking in treated areas several days post-application does not require 

contact with treated surfaces except for soles of shoes or boots thus exposure is not 

expected. 

In addition, according to the RED document, the vapor pressure of d-limonene is 2 mm 

Hg at 20o

C. As such, it is expected to volatilize comparatively quickly. Therefore, a 

post-application exposure assessment was not conducted here. 

RESIDENTIAL EXPOSURE

The label statements related to some of the noncrop areas could suggest use in residential 

settings (ie., borders, driveways, sidewalks, around mature landscaping trees, shrubs, 

foliage and ornamentals, around buildings). Based on the use instruction and general 

“tone” of the label, ARIA/RD believes the product is designed/intended for 

commercial/industrial use. Although, there is nothing that would preclude use by 

homeowners. If the product is applied around residential settings, there is the possibility 

of post-application exposures to residents. The HED ExpoSAC believes residential 

postapplication exposure to treated ornamentals plantings is negligible and therefore it is 

not assessed. Materials applied to home lawns are routinely assessed. 

cc:M.Dow(RIMUERB) 

RDI:J. Redden, N. Taydayon, M. Rust 

M.I.Dow:S7824:PY1:(703)305-5533:RIMUERB:7505P