1 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

November 3, 2014 

 PC Code: 055501 

MEMORANDUM DP Barcode: D422219 

SUBJECT: Registration Review: Preliminary Problem Formulation for Environmental Fate, 

Ecological Risk, Endangered Species, and Human Health Drinking Water 

Exposure Assessments for Ethoxyquin 

FROM: James N. Carleton, Ph.D. 

 Environmental Risk Branch IV 

Environmental Fate and Effects Division (7507P) 

REVIEWED 

BY: Elyssa Arnold, MEM, MPH, Acting Risk Assessment Process Leader 

 Thomas Steeger, Ph.D., Senior Science Advisor 

 Environmental Risk Branch IV 

Environmental Fate and Effects Division (7507P) 

THROUGH: Thomas Steeger, Ph.D., Acting Branch Chief 

Environmental Risk Branch IV 

 Environmental Fate and Effects Division (7507P) 

 

TO: Khue Nguyen, Chemical Review Manager 

 Tom Moriarty, Team Leader 

 Neil Anderson, Branch Chief 

Risk Management and Implementation Branch I 

Pesticide Re-evaluation Division (7508P) 

The Environmental Fate and Effects Division (EFED) has completed the preliminary problem 

formulation for the ecological risk, environmental fate, endangered species, and drinking water 

assessments to be conducted as part of the Registration Review of ethoxyquin. The problem 

formulation describes the methods planned to be used during the completion of drinking water 

and ecological risk assessments in support of Registration Review and provides an overview of 

the environmental fate, ecological effects, and potential risks associated with the use of 

ethoxyquin as well as uncertainties unique to the risk assessment of ethoxyquin. Uncertainties 

include: 
2 

Data Needs 

 The fate database is incomplete based on the environmental fate data requirements 

outlined in the Code of Federal Regulations Title 40 Part 158 (40CFR158) Subpart N1

 and 

data are needed to reduce uncertainty in the risk assessment. Additional data on the 

following fate parameters are recommended.

o Hydrolysis data (OCSPP Guideline 835.2120). The previously submitted study 

(MRID 437531-01) did not definitively identify four major degradates (analytical 

methodology was not adequate to provide definitive structural identification) and 

therefore does not fulfill the guideline requirement for a hydrolysis study.

o Adsorption/desorption data (OCSPP Guideline 835.1230).

o Aqueous photolysis data (OCSPP Guideline 835.2240). 

o Aerobic aquatic metabolism data (OCSPP Guideline 835.4300). 

 The ecotoxicity database is incomplete for the purposes of assessing risk to aquatic 

organisms. Additional data on the following taxa are recommended: 

o Daphnid chronic toxicity test (OCSPP 850.1300)

o Freshwater fish early-life stage toxicity test (OCSPP 850.1400)

o Vascular aquatic plant toxicity test (OCSPP 850.4400)

o Non-vascular aquatic plant toxicity test (OCSPP 850.4500)

Other Major Uncertainties 

 Although ethoxyquin is only applied within indoor pear storage and packing facilities, it is 

EPA’s understanding that such facilities may be hosed down for cleaning purposes and 

that packing facilities using the drench or spray applications may generate waste water 

containing ethoxyquin during this process. However, disposal practices for the resulting 

drainage that may contain ethoxyquin residues are not well defined. Information 

concerning disposal of the waste water has been requested from the registrants and 

industry trade organizations, but has not been received. Although the limited nature of the 

application of ethoxyquin may preclude the possibility of ecological exposure, until the 

requested information has been received and evaluated, such exposures to aquatic 

organisms cannot be ruled out. 

 When facilities in which thermal fogging is employed for ethoxyquin are ventilated, 

exposure of non-target organisms to ethoxyquin residues in vapor and/or in aqueous 

solution (following deposition or partitioning to surface waters), may occur. Based upon 

conservative screening-level calculations employing the limited available chemical 

property and toxicity data, consequent risks to mammals are considered unlikely; 

however, risks to aquatic taxa cannot be ruled out. 

 

1 CFR. 2013. Title 40 (Protection of the Environment), Chapter 1 (Environmental Protection Agency), Subchapter E (Pesticide 

Programs), Part 158 (Data Requirements for Pesticides), Subpart N (Environmental Fate) http://www.ecfr.gov/cgi-bin/textidx?c=ecfr&SID=ff5c7fef3645e7cd5abceca0b597bccb&tpl=/ecfrbrowse/Title40/40cfr158_main_02.tpl
3 

Table of Contents

1. Executive summary ................................................................................................................. 3

2. Introduction ............................................................................................................................. 4

3. Use Characterization ............................................................................................................... 4

4. Conclusions from Previous Risk Assessments ....................................................................... 5

a. Previous Assessments ...........................................................................................................5

b. Clean Water Act Programs ...................................................................................................5

5. Environmental Fate and Transport.......................................................................................... 5

6. Receptors................................................................................................................................. 6

a. Effects to Aquatic and Terrestrial Organisms .......................................................................6

b. Ecological Incidents ..............................................................................................................7

7. Exposure Pathways of Concern .............................................................................................. 8

8. Analysis Plan .......................................................................................................................... 9

a. Ecological Risk Assessment .................................................................................................9

b. Drinking Water ...................................................................................................................10

c. Monitoring Data ..................................................................................................................10

9. Endangered Species Assessments ......................................................................................... 10

10. Endocrine Disruptor Screening Program ........................................................................... 10

11. Preliminary Identification of Data Gaps ............................................................................ 11

a. Environmental Fate .............................................................................................................11

b. Effects .................................................................................................................................12

12. References .......................................................................................................................... 13

1. Executive summary 

The problem formulation for the Registration Review of the fungicide ethoxyquin describes the 

methods planned to be used during the completion of drinking water and ecological risk 

assessments. This document also provides a preliminary overview of the environmental fate, 

ecological effects, and potential risks and uncertainties associated with the use of ethoxyquin. 

Ethoxyquin is an antioxidant registered for post-harvest use on pears to control scald2. 

Application methods include impregnated paper wraps, thermal fogging, and spray or drench. 

Available environmental fate and ecotoxicity data are limited. Ethoxyquin is a soluble and 

volatile compound with a hydrolysis half-life of approximately 7 days at pH 7. Toxicity studies 

demonstrate slight to moderate acute toxicity to aquatic animals and practically no toxicity to 

terrestrial animals on an acute exposure basis. No prior quantitative ecological risk assessments 

have been performed by the Agency for ethoxyquin due to uncertainties regarding outdoor 

exposure pathways. 

 

2

 Scald is characterized as a physiological disease that produced brown to black discoloration of the skin of multiple varieties of pears and has been 

associated with fruit that have turned color in storage and lost their capacity to ripen normally. Although the discoloration is initially superficial, it 

can progress to where fruit skin sloughs off readily and is followed by decay (Washington State University Tree Fruit Research and Extension 

Service http://postharvest.tfrec.wsu.edu/marketdiseases/pearcommonscald.html). 
4 

2. Introduction 

EFED reviewed available toxicity, exposure, and usage information to determine if sufficient data 

are available to support the Registration Review of ethoxyquin. The only available risk 

assessment is a 2008 assessment of the use of ethoxyquin applied via thermal fogging on postharvest pears (D341198, 341199, 341201). In addition, EFED considered the latest Agency 

science policies and risk assessment methodologies in determining whether additional data should 

be recommended. The structure of ethoxyquin, as well as the chemical name and other identifiers 

can be found in Section 5. 

3. Use Characterization 

The fungicide ethoxyquin (6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline) is a quinolone-based 

antioxidant used to control scald (browning) in post-harvest pears. Registered end-use products 

include impregnated materials, i.e., PEAR WRAP® III (Reg. no. 61718-1), PEAR WRAP® I (Reg 

no. 61718-4), ETHOXYWRAP® (Reg. No. 84127-2), BURROWS® E WRAP (Reg. no. 85199-4 

and BURROWS CE WRAP® (Reg. no. 85199-11), a soluble concentrate (XEDAQUIN®; Reg. no. 

64864-60), and an emulsifiable concentrate (XEDAQUIN® DRENCH; Reg. no. 64864-58). 

Another emulsifiable concentrate (ECOFOG-180; Reg no. 64864-64) is registered for 

manufacturing use only. All applications are made to pears in storage and prior to packing. 

Application methods include thermal electrofogging, drench and line spraying, and use of 

ethoxyquin-impregnated paper. The uses are summarized below in Table 1. 

Table 1. Ethoxyquin Use Table1

EPA 

Registration 

Numbers 

Application 

Type/ 

Equipment 

Single 

Application 

Rate 

Max # 

Applications 

Max Dose/ 

Crop 

Cycle Application Specific Restrictions 

64864-60 

Xeda Brand 

Thermal 

Electrofogger 

60 g per 

metric ton of 

fruit (1.9 oz 

per ton) 

NS NS (none) 

64864-58 

Drench 

2700 ppm 1 2700 ppm 

 Do not use in combination with line spray. 

 Can be applied as a single or split 

application as long as the maximum dose 

of 2700 ppm is not exceeded. 

Line Spray (on 

brush bed or 

conveyor rolls) 

 Do not use in combination with drench. 

 Can be applied as a single or split 

application as long as the max dose of 2700 

ppm is not exceeded. 

61718-1 

61718-4 

84127-2 

85199-4 

85199-11 

Impregnated 

paper 

1000 ppm NS see 

restrictions 

 Wrap fruit within 1 week post-harvest. 

 Wraps contain a maximum of 1,000 ppm 

ethoxyquin. They can be used on pears that 

have received prior treatment with 

ethoxyquin providing those pears were 

sprayed only once with no more than 1700 

ppm of ethoxyquin, or drenched only once 

with no more than 1,000 ppm of 

ethoxyquin. 

 Do not re-use fruit wraps. 1 Table prepared by the Biological and Economic Analysis Division (BEAD) on May 16, 2014. 
5 

4. Conclusions from Previous Risk Assessments 

a. Previous Assessments 

A 2008 assessment (USEPA, D341198, D341199, D341201) of the then-pending Section 3 

registration of the soluble concentrate (ECOFOG®-180; Reg. no. 64864-60) intended for use in 

thermal fogging, noted that the label directions specify that applications take place within a 

treatment room “enclosed with” plastic sheeting and sealed with duct tape. Because this method 

of application is limited to indoor locations, the previous review concluded that the potential for 

environmental exposures was limited, and that potential risks to terrestrial and aquatic non-target 

organisms, including Federally listed threatened or endangered (hereafter referred to as “listed”) 

species, were therefore not anticipated. Drinking water exposures were not specifically addressed. 

b. Clean Water Act Programs 

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

under section 303(d) of the Clean Water Act.3 No Total Maximum Daily Loads (TMDL) or 

section 304(a) ambient water quality criteria have been developed for ethoxyquin.4 Aquatic life 

benchmarks5

 have not been established for ethoxyquin; however, any data submitted or otherwise 

located as part of the Registration Review process may be used to develop aquatic life 

benchmarks if applicable. 

5. Environmental Fate and Transport 

No acceptable environmental fate data are currently available for ethoxyquin. A hydrolysis study 

(MRID 437531-01), conducted in 1995, was determined by EFED to be “scientifically valid,” but 

the study did not meet Subdivision N guidelines, because four major degradates (i.e., each > 10% 

of applied radioactivity) were isolated, but were only tentatively identified, with more than one 

possible structure proposed for each, based upon mass spectral information. Parent ethoxyquin 

decayed with calculated half-lives of 3.7, 6.7, and 9.3 days in aqueous solutions buffered at pH 5, 

7, and 9, respectively. The available chemical properties and environmental fate parameters are 

summarized in Table 3. Due to limited data, there is uncertainty regarding the extent to which the 

compound may be subject to abiotic routes of degradation such as photolysis, or biotic routes of 

degradation in aerobic or anaerobic environments. 

No monitoring data are available for ethoxyquin. There is uncertainty whether this reflects the 

low levels in the environment or whether current monitoring programs may not include 

ethoxyquin as an analyte. 

 

3

 Specific state causes of impairment that make up the national pesticides cause of impairment group are listed at 

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

4

 Specific state pollutants that make up the National Pesticides Pollutant Group and have TMDLs are listed at 

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

oup_name=PESTICIDES

5

 Aquatic Life Benchmarks are available at http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm 
6 

Table 2. Ethoxyquin Chemical Identity Table

Code Name/ Synonym Chemical Name Chemical Structure 

Ethoxyquin 6-ethoxy-1,2-dihydro-2,2,4-

trimethylquinoline 

CAS No.: 91-53-2

Formula: C14H19NO 

MW: 217.31 g/mol 

Table 3. Ethoxyquin Chemical Properties and Environmental Fate Parameters

Parameter Value Source

Selected Physical/Chemical Parameters 

Vapor pressure (25 °C) 2.6 x 10-4 torr MRID 439474-01

Aqueous solubility (25C) 170 ppm MRID 439723-01

Henry’s Law Constant (25°C) 4.37 x 10-7 atm·m3·mol-1 Calculated 

Log octanol-to-water partition coefficient 

(log KOW) (25°C) 2.45 MRID 439632-01

Dissociation constant (pKa) 8.65 MRID 491489-05

Persistence in Water

Hydrolysis half-life (25C) 

pH 5: 3.7 d 

pH 7: 6.7 d 

pH 9: 9.3 d 

MRID 437531-01

6. Receptors 

a. Effects to Aquatic and Terrestrial Organisms 

Two aquatic toxicity studies are available for ethoxyquin, i.e., acute toxicity studies on freshwater 

fish and on freshwater invertebrates. These studies show that ethoxyquin is slightly toxic to the 

rainbow trout (Oncorhynchus mykiss; LC50 = 18 mg a.i./L) and moderately toxic to the 

invertebrate waterflea (Daphnia magna; EC50 = 2 mg a.i./L) on an acute exposure basis. Both 

studies were conducted using flow-through systems with methanol as a solvent. See Table 4 for 

details. 

One avian toxicity study is available for ethoxyquin, which demonstrates that ethoxyquin is 

practically non-toxic to bobwhite quail (Colinus virginianus) on a sub-acute dietary exposure 

basis (LC50 >5850 mg a.i./kg-bw, no mortality observed in the study). Studies on the laboratory 

rat (Rattus norvegicus) show that ethoxyquin is practically non-toxic to mammals on an acute oral 

basis (LD50 = 1726 mg a.i./kg-bw). In an acute inhalation study conducted on the laboratory rat at 

1.97 mg a.i./L, no LC50 was established but clinical signs of toxicity included tremors, unkempt 
7 

appearance and reductions in body weight. No 2-generation reproduction study is available, but a 

developmental study on the laboratory rat demonstrated maternal toxicity at 150 mg a.i./kgbw/day (NOAEL = 50 mg a.i./kg-bw/day); however, offspring did not demonstrate adverse 

effects up to the highest level tested (350 mg a.i./kg-bw/day). See Table 4 for details. 

No other data on the effects of ethoxyquin on non-target biological receptors have been submitted 

to the Agency. 

Table 4. Summary of the Most Sensitive Endpoints from Toxicity Studies for Ethoxyquin 

Taxonomic 

Group Study Type Species Toxicity Value (measured a.i.) 

Acute 

Toxicity 

Classification 

MRID 

(Study 

Classification) 

Aquatic Toxicity Endpoints 

Freshwater Fish 

& Aquaticphase 

Amphibians 

Acute 

Rainbow trout 

(Oncorhynchus 

mykiss) 

96 hr LC50 = 18 

mg/L Slightly toxic 43978301 

(Acceptable) 

Freshwater 

Invertebrates Acute Daphnia magna

48 hr LC50 = 2 

mg/L 

Moderately 

toxic 

43978401 

(Acceptable) 

Terrestrial Toxicity Endpoints

Birds, Reptiles, 

& Terrestrialphase 

Amphibians 

Sub-acute 

dietary 

Bobwhite quail 

(Colinus 

virginianus) 

LC50 >5850 mg/kgbw 

Practically 

nontoxic 

43978101 

(Acceptable) 

Mammals 

Acute oral 

Laboratory rat 

(Rattus 

norvegicus) 

LD50 = 1726 

mg/kg-bw (M&F)

Practically 

nontoxic 

43885901 

(Acceptable) 

Acute 

inhalation Laboratory rat 4 hr LC50 >1.97 mg/L 

Toxicity 

category III 

43894101 

(Acceptable) 

Developmental Laboratory rat 

NOAEL = 50 

LOAEL = 150 

mg/kg-bw/day 

Not 

applicable 

44098901 

(Acceptable) 

b. Ecological Incidents 

The ecological incident information system (EIIS) is a database maintained by the Office of 

Pesticide Programs (OPP) containing ecological incidents that have been reported to the Agency. 

When available, EIIS includes date and location of an incident, type and magnitude of effects 

observed in various species, use(s) of pesticides known or suspected of contributing to the 

incident, and results of any chemical residue analysis or other analyses conducted during the 

incident investigation. The Avian Monitoring System (AIMS) is a database administered by the 

American Bird Conservancy that contains publicly available data on reported avian incidents 

involving pesticides. 

As of August 28, 2014, there were no ecological incidents reported in EIIS or AIMS for 

ethoxyquin. There were also no incidents reported in aggregate incident reports. 
8 

7. Exposure Pathways of Concern 

Previous assessments have concluded that the use patterns of ethoxyquin imply the lack of any 

meaningful transport mechanisms of the chemical to aquatic or terrestrial habitats, and therefore 

the absence of any potential exposure pathway for aquatic or terrestrial organisms. However, 

given EPA’s current understanding that pear treatment facilities may generate waste water, which 

despite the chemical’s volatility could contain ethoxyquin residues, there is uncertainty regarding 

common handling practices of the resulting waste water. Therefore, there is uncertainty regarding 

whether this water might be released to the outdoor environment (e.g., to a holding pond), where 

ethoxyquin exposures to non-target organisms could occur. Waste water containing ethoxyquin 

residues may result from (1) washing out of treatment facilities in which thermal fogging 

applications of ethoxyquin occurred or (2) waste water generated from packing facilities in which 

drench or spray applications of ethoxyquin are used. In order to better understand this potential 

pathway, EPA has requested information about waste water treatment in pear storage and packing 

facilities from the ethoxyquin registrants and industry trade organizations. 

EFED notes that the following language is included on the labels for the spray/drench and thermal 

fogger products, EPA Reg. No. 64864-58 and 64864-60: “Do not discharge effluent containing 

this product into lakes, streams, ponds, estuaries, oceans, or other waters unless in accordance 

with the requirements of a National Pollutant Discharge Elimination System (NPDES) permit and 

the permitting authority has been notified in writing prior to discharge. Do not discharge effluent 

containing this product to sewer systems without previously notifying the local sewage treatment 

plant authority. For guidance, contact your State Water Board or Regional Office of the EPA.” 

Because ethoxyquin is volatile, when facilities in which thermal fogging is employed to apply the 

chemical are ventilated, exposure of non-target organisms to residues in vapor form and/or in 

aqueous solution (following deposition or partitioning to surface waters), may occur. Because 

EPA currently lacks information on ventilation practices for pear handling and storage facilities, 

conservative screening-level calculations were conducted to represent these exposure pathways. 

Non-target organisms that might be exposed include terrestrial wildlife (i.e., birds [which serve as 

surrogates for terrestrial-phase amphibians and reptiles] and mammals), aquatic invertebrates and 

fish (which serve as surrogates for aquatic-phase amphibians), and terrestrial and aquatic plants. 

For the screening-level calculations, it was assumed that concentrations of ethoxyquin would be 

at their maximum possible values, i.e., saturation in air, and in water. The saturation concentration 

in water is given in Table 3. The saturation air concentration at 25oC was calculated as follows: 

ܥ ௥௜௔ൌ ܸܲ ൈ ܯܹ ൈ 1000

760 ൈ ܸ௠

ܮ݉݃/	0.003 ൌ

where: 

Cair = air vapor concentration (mg/L) of the pesticide at saturation 

VP = vapor pressure (2.6 x10-4 torr) 

Vm = volume in liters (24.45) occupied by 1 mol of gas at 25oC and 1atm, as calculated using the 

ideal gas law (PV = nRT) 

MW = molecular weight (217.31 g/mol) 

760 = conversion from torr to atm 

1000 = conversion from m3

 to L 
9 

Based upon the saturation air concentration and results of the acute inhalation rat study (Table 4), 

a back-of-the-envelope, worst-case risk quotient (RQ; the ratio of exposure to toxicity) of <0.0015 

is calculated; therefore the likelihood of adverse effects on non-target mammals from acute 

inhalation exposure to ethoxyquin is considered low. Inhalation toxicity data are not available for 

birds; however, the likelihood of adverse effects on birds, reptiles and terrestrial-phase 

amphibians from acute inhalation exposure is considered low based on the available mammalian 

inhalation and avian sub-acute dietary toxicity data and that the highest inhalation exposure levels 

are likely confined to indoor areas. 

Based upon the water saturation concentration of 170 mg/L (Table 3) for ethoxyquin, worst-case 

RQs of 9.5 and 85.1 are estimated for freshwater fish and aquatic invertebrates, respectively 

(Table 4); therefore risks to these taxa, including aquatic-phase amphibians cannot be ruled out at 

this time. Water containing ethoxyquin residues may also be used as drinking water by terrestrial 

animals. However, based on the low dietary toxicity of ethoxyquin to birds and mammals this 

exposure pathway is not expected to result in risks of concern. 

Drinking water and inhalation exposure pathways are typically considered using the SIP 

(Screening Imbibition Program) and STIR (Screening Tool for Inhalation Risk) screening 

methods. However, due to the lack of acute oral and chronic toxicity data for birds, quantitative 

use of these tools is not possible for ethoxyquin at this time. SIP and STIR are described in detail 

at: http://www.epa.gov/oppefed1/models/terrestrial/index.htm. 

8. Analysis Plan 

a. Ecological Risk Assessment 

Given the slight toxicity of ethoxyquin to freshwater fish, and the chemical’s moderate toxicity to 

freshwater aquatic invertebrates, ethoxyquin could pose risks to aquatic organisms if it were 

released or discharged into surface waters. No data are available on the chronic toxicity of 

ethoxyquin to aquatic organisms. Given the chemical’s limited use patterns, there do not appear to 

be major transport pathways through which non-target receptors are likely to be exposed to 

substantial residues of ethoxyquin. However, uncertainty exists concerning the routine handling 

of pear treatment facility wash water and waste water, and concerning procedures involved in the 

ventilation of thermal fogging facilities. On the basis of conservative calculations and in the face 

of these uncertainties, risks to non-target organisms cannot be definitively ruled out. OPP has 

sought to address these uncertainties with questions asked of the registrants and industry trade 

organizations. Pending receipt of additional information, EFED plans to quantitatively evaluate 

potential risks to aquatic organisms exposed to waste water from the spray/drench uses in pear 

packing facilities. EFED may also further refine calculations employed to quantify exposures 

resulting from ventilation of thermal fogging facilities. 

The use of ethoxyquin in impregnated paper is not expected to result in any significant 

environmental exposure and therefore will not be assessed by EFED. 
10 

Since the use of ethoxyquin is limited to indoors, there is a low likelihood of exposure to 

terrestrial animals foraging on grass, broadleaf plants, or insects. Therefore, potential risks to 

these organisms as well as terrestrial plants will not be assessed given the low likelihood of 

exposure to ethoxyquin residues. 

b. Drinking Water 

Given ethoxyquin’s limited use patterns, there are no known transport pathways by which humans 

might plausibly be exposed to ethoxyquin residues in drinking water. Nevertheless, questions 

exist concerning the handling of pear treatment facility wash water, which OPP has asked the 

registrants to address. Pending receipt of this information, EFED will evaluate whether a 

quantitative assessment of drinking water exposures is appropriate.

If either ecological or drinking water exposure calculations are deemed necessary, EFED may 

employ standard models to evaluate potential human and/or ecological exposures as described at 

http://www.epa.gov/pesticides/science/models_db.htm. In addition, the Exposure and Fate 

Assessment Tool (E-FAST) or other available models may be used to assess exposures resulting 

from wash water disposal in drains, waste water systems, storm sewers, etc. E-FAST is described 

in detail at http://www.epa.gov/oppt/exposure/pubs/efast.htm. 

c. Monitoring Data 

As noted earlier, EPA is not aware of any monitoring for ethoxyquin that has been conducted by 

federal or state agencies. Should such data become available, they will be considered in the 

assessment. 

9. Endangered Species Assessments 

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), the 

Agency will evaluate risks to listed species from registered uses of pesticides in Registration 

Review. The process for evaluating potential risks to listed species is further described at 

http://www.epa.gov/oppfead1/endanger/litstatus/riskasses.htm. 

 

10. Endocrine Disruptor Screening Program 

Ethoxyquin was not included in the first group of 67 chemicals issued an order to conduct Tier 1 

EDSP testing. Ethoxyquin is also not on the second list of chemicals for Tier 1 EDSP screening. 

For additional information the EDSP program, visit http://www.epa.gov/endo/. 
11 

11. Preliminary Identification of Data Gaps 

a. Environmental Fate 

Table 5 identifies environmental fate studies by master record identification (MRID) number that 

offer data for each guideline requirement, as well as study classifications and whether or not 

further data are needed in order to support risk assessment. 

Table 5. Submitted Environmental Fate Data for Ethoxyquin 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications

Are 

additional 

data needed 

for risk 

assessment?

Justification and Assumptions EPA 

will Make in Absence of Data 

835.2120 Hydrolysis 437531-01 Supplemental Yes In the absence of data, stability will be 

assumed. 

835.2240 Aqueous 

photolysis (None) (Not 

applicable) Yes 

Data will be used to assess potential 

aquatic exposure. In the absence of data, 

stability will be assumed. 

835.2410 Soil photolysis (None) (Not 

applicable) No Terrestrial exposure will not be 

assessed.

835.4100 Aerobic soil 

metabolism (None) (Not applicable) No Terrestrial exposure will not be 

assessed.

835.4200 Anaerobic soil 

metabolism (None) (Not 

applicable) No Terrestrial exposure will not be 

assessed.

835.4300 Aerobic aquatic 

metabolism (None) (Not applicable) Yes 

Data will be used to assess potential 

aquatic exposure. In the absence of data, 

stability will be assumed. 

835.4400 

Anaerobic 

aquatic 

metabolism 

(None) (Not 

applicable) No 

Data are not expected to impact risk 

assessment.

835.1230 

835.1240 

Adsorption/ 

desorption and 

leaching 

(None) (Not 

applicable) Yes 

Data will be used to assess potential 

aquatic exposure. In the absence of data, 

stability will be assumed. 

835.1410 Volatility – 

laboratory (None) (Not applicable) No Data are not expected to impact risk assessment.

835.6100 Terrestrial field 

dissipation (None) (Not 

applicable)

No Terrestrial exposure will not be assessed 

given the indoor use of the product. 850.6100 Analytical 

method in soil (None) (Not 

applicable)

835.6200 Aquatic field 

dissipation (None) (Not 

applicable) No Data are not expected to impact risk 

assessment.

850.6100 Analytical 

method in water (None) (Not 

applicable)

165-4 

(850.1730) 

Fish 

bioconcentration (None) (Not applicable) No Data are not expected to impact risk 

assessment.
12 

b. Effects 

Table 6 and Table 7 identify ecological effects studies by MRID that offer data for each 

guideline requirement, as well as study classifications and whether or not further data are needed 

in order to support risk assessment. 

Table 6. Submitted Aquatic Ecological Effects Data for Ethoxyquin 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Are 

additional 

data needed 

for risk 

assessment? 

Justification and Assumptions 

EPA will Make in Absence of 

Data 

 850.1010 

Freshwater 

invertebrate 

acute toxicity 

439784-01 Acceptable No N/A 

850.1025 

850.1035 

850.1045 

850.1055 

Saltwater 

invertebrate 

acute toxicity 

(None) (N/A) No 

Significant exposure in 

estuarine/marine environments is 

not expected. 

 850.1075 Freshwater fish 

acute toxicity 439783-01 Acceptable No N/A 

850.1075 Saltwater fish 

acute toxicity (None) (N/A) No 

Significant exposure in 

estuarine/marine environments is 

not expected.

850.1300 

Freshwater 

invertebrate 

life cycle 

(None) (N/A) Yes 

There is potential for chronic 

exposure to aquatic organisms. In 

the absence of data, toxicity will be 

assumed.

850.1350 

Saltwater 

invertebrates 

life cycle 

(None) (N/A) No 

Significant exposure in 

estuarine/marine environments is 

not expected.

850.1400 Freshwater fish 

early-life stage (None) (N/A) Yes 

There is potential for chronic 

exposure to aquatic organisms. In 

the absence of data, toxicity will be 

assumed.

850.1400 Saltwater fish 

early-life stage (None) (N/A) No 

Significant exposure in 

estuarine/marine environments is 

not expected.

850.1500 Fish life cycle (None) (N/A) No Data are not expected to impact 

risk assessment.

850.4400 

Aquatic plant 

Toxicity Test 

using Lemna

spp. 

(None) (N/A) Yes

There is potential for exposure to 

aquatic plants. In the absence of 

data, toxicity will be assumed.

850.4500 Algal toxicity (None) (N/A) Yes

There is potential for exposure to 

aquatic plants. In the absence of 

data, toxicity will be assumed.

850.4550 Cyanobacteria (None) (N/A) No Data is not expected to impact risk 

assessment.
13 

Table 7. Submitted Terrestrial Ecological Effects Data for Ethoxyquin 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Are 

additional 

data needed 

for risk 

assessment? 

Justification and Assumptions EPA 

will Make in Absence of Data 

 850.2100 Avian oral 

toxicity (None) (N/A) No Terrestrial exposure will not be 

assessed. 

 850.2200 Avian dietary 

toxicity 439781-01 Acceptable No N/A 

 850.2300 Avian 

reproduction (None) (N/A) No 

Terrestrial exposure will not be 

assessed.

Nonguideline Avian 

inhalation (None) (N/A) No Terrestrial exposure will not be 

assessed.

 850.3020 

Honey bee 

acute contact 

toxicity 

(None) (N/A) No 

Terrestrial exposure will not be 

assessed.

850.3030 

Honey bee 

residue on 

foliage 

(None) (N/A) No 

Terrestrial exposure will not be 

assessed.

 850.3040 Field testing 

for pollinators (None) (N/A) No Terrestrial exposure will not be 

assessed.

850.4100 Seedling 

Emergence (None) (N/A) No Terrestrial exposure will not be assessed.

850.4150 Vegetative 

Vigor (None) (N/A) No Terrestrial exposure will not be assessed.

12. References 

Mackay, D., Shiu, W. Y., Ma, K. C., & Lee, S. C. 1999. Physical–chemical properties and 

environmental fate and degradation handbook. CRCnet Base. Boca Raton, FL: Chapman 

& Hall/CRCnet Base. 

USEPA, 2008. Review of Section 3 New Application Method, Thermal Fogging, for the use of 

Ethoxyquin (Xedaquin A) on Pears. Memorandum from Marietta Echeverria, 

Environmental Fate and Effects Division, to John Bazuin and Tony Kish, Registration 

Division, Office of Pesticide Programs, U.S. Environmental Protection Agency. DP 

Barcodes 341198, 341199, 341201. Dated March 31, 2008. 

Studies by MRID 

MRID 43753101. Reynolds, J.; Campbell, M. (1995) Hydrolysis of (carbon 14)-Ethoxyquin: Lab 

Project Number: ABL 95011: RPT00229: X336. Unpublished study prepared by 

XenoBiotic Labs, Inc. 160 p. 
14 

MRID 43885901. Varsho, B. (1995) Acute Oral Toxicity Study of Ethoxyquin in Albino Rats: 

Final Report: Lab Project Number: WIL-273001. Unpublished study prepared by WIL 

Research Labs, Inc. 86 p. 

MRID 43894101. Ulrich, C. (1996) Acute Inhalation Toxicity Study of Ethoxyquin in Rats: Final 

Report: Lab Project Number: WIL-273006. Unpublished study prepared by WIL Research 

Labs, Inc. 81 p. 

MRID 43947401. Schetter, J.; Kogovsek, L. (1996) Ethoxyquin--Vapor Pressure: Lab Project 

Number: 4368-95-0189-AS-001: 4368-95-0189-AS-000. Unpublished study prepared by 

Department of Analytical Services, Ricerca, Inc. 55 p. 

MRID 43963201. Lorence, P. (1996) Ethoxyquin--Octanol/Water Partition Coefficient: Lab 

Project Number: 4368-95-0204-AS-001: 4368-95-0204-AS-000. Unpublished study 

prepared by Ricerca, Inc. 52 p. 

MRID 43972301. Lorence, P. (1996) Ethoxyquin--Solubility: Lab Project Number: 4368-95-

0177-AS-001: 4368-95-0177-AS-000: 4368-95-0177-AS. Unpublished study prepared by 

Dept. of Analytical Services, Ricerca, Inc. 50 p. 

MRID 43978101. Palmer, S.; Martin, K.; Beavers, J. (1996) Ethoxyquin Technical: A Dietary 

LC50 Study with the Northern Bobwhite: Lab Project Number: 442-101. Unpublished 

study prepared by Wildlife Int'l. Ltd. 45 p. 

MRID 43978301. Drottar, K.; Swigert, J. (1996) Ethoxyquin: A 96-Hour Flow-Through Acute 

Toxicity Test with the Rainbow Trout (Oncorhychus mykiss): Final Report: Lab Project 

Number: 442A-101A: 442/122095/RBT-96H2/CHP107: 442A-101. Unpublished study 

prepared by Wildlife International Ltd. 65 p. 

MRID 43978401. Drottar, K.; Swigert, J. (1996) Ethoxyquin: A 48-Hour Flow-Through Acute 

Toxicity Test with the Cladoceran (Daphnia magna): Final Report: Lab Project Number: 

442A-102: 442/122095/DAP-48H2/CHP107. Unpublished study prepared by Wildlife 

Int'l. Ltd. 66 p. 

MRID 44098901. Nemec, M. (1996) A Developmental Toxicity Study of Ethoxyquin in Rats: 

Final Report: Lab Project Number: WIL-273009. Unpublished study prepared by WIL 

Research Labs., Inc. 360 p. 

MRID 49148905. Todhunter, J.; Tatanus, C. (2013) Product Chemistry, Series 63 (Physical & 

Chemical Properties) Ethoxyquin from Alternate Sources for Formulation of E Wrap and 

CE Wrap. Project Number: BURROWS/E/CE/WRAP/ALT/EQ/SERIES/63/2013. 

Unpublished study prepared by SRS International Corporation. 11p.