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Propylene Glycol, Dipropylene Glycol and Triethylene Glycol Registration Review Team

Human Health

Nathan Mottl

Michelle Centra

William Hazel

Environmental Fate and Effects

Siroos Mostaghimi

Srinivas Gowda

Najm Shamim

David Bays

Risk Management

Elizabeth Hernandez

Andrew Bryceland

Office of General Counsel

Philip Ross
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Table of Contents

1 Introduction............................................................................................................................. 5

1.1 Statutory and Regulatory Authority ................................................................................. 5

1.2 Case Overview ................................................................................................................. 8

1.3 Chemical Identification and Properties............................................................................ 8

1.4 Use/Usage Description................................................................................................... 10

1.4.1 Registrations ........................................................................................................... 10

1.4.2 Summary of Registered Uses.................................................................................. 10

1.4.3 Usage Information .................................................................................................. 11

1.5 Regulatory History ......................................................................................................... 11

1.5.1 Recent/Pending Regulatory Actions....................................................................... 11

1.5.2 Tolerance Information ............................................................................................ 11

1.6 Incidents......................................................................................................................... 12

1.6.1 Human Health ......................................................................................................... 12

1.6.2 Ecological ............................................................................................................... 12

2 Anticipated Data Needs ........................................................................................................ 12

3 Human Health Risk Assessment........................................................................................... 12

3.1 Existing Toxicological Endpoints.................................................................................. 13

3.2 Dietary Exposure............................................................................................................ 13

3.2.1 Food ........................................................................................................................ 13

3.2.2 Drinking Water ....................................................................................................... 13

3.3 Occupational and Residential Exposures....................................................................... 14

3.3.1 Occupational Handler Exposure ............................................................................. 14

3.3.2 Residential Handler Exposures............................................................................... 14

3.3.3 Occupational Post-Application Exposures ............................................................. 15

3.3.4 Residential Post-Application Exposures................................................................. 15

3.4 Aggregate and Cumulative Exposure............................................................................. 16

3.4.1 Aggregate Exposures.............................................................................................. 16

3.4.2 Cumulative Exposures............................................................................................ 16

4 Environmental Risk Assessment........................................................................................... 16

4.1 Environmental Fate Assessment .................................................................................... 16

4.2 Conceptual Models for Environmental Exposure Pathways.......................................... 17

4.3 Ecological Effects Assessment....................................................................................... 17

4.3.1 Mechanism of Action.............................................................................................. 17

4.3.2 Measures of Effect (Ecotoxicology Endpoints)...................................................... 18

4.4 Exposure Analysis Plan.................................................................................................. 19

4.4.1 Aquatic and Terrestrial Wildlife Exposure Estimates ............................................ 19

4.5 Effects Analysis Plan ..................................................................................................... 19

4.5.1 Endangered Species Effects Determination............................................................ 19

5 Endocrine Disruptor Screening Program (EDSP)................................................................. 20

6 Guidance for Commenters.................................................................................................... 21

6.1 Preliminary Work Plan................................................................................................... 21

6.1.1 Trade Irritants.......................................................................................................... 21

6.1.2 Water Quality.......................................................................................................... 21

6.1.3 Environmental Justice............................................................................................. 22

6.1.4 Structure Activity Relationships............................................................................. 22
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6.1.5 Additional Information ........................................................................................... 23

7 Next Steps............................................................................................................................. 23

8 References............................................................................................................................. 24

Appendix A Toxicology Profile............................................................................................... 34

Appendix B Product Chemistry............................................................................................... 46

Appendix C Ecotoxicology Profile for Propylene Glycol and Dipropylene Glycol ............... 48

Appendix D Ecotoxicology Profile for Triethylene Glycol..................................................... 55

List of Tables

Table 1 – Summary of Anticipated Risk Assessments and Data Needs: Propylene Glycol.......... 6

Table 2 – Summary of Anticipated Risk Assessments and Data Needs: Dipropylene Glycol...... 6

Table 3 – Summary of Anticipated Risk Assessments and Data Needs: Triethylene Glycol ....... 7

Table 4 – Anticipated Registration Review Schedule .................................................................... 7

Table 5- Chemical Identification of Triethylene, Propylene and Dipropylene Glycols................. 8

Table 6– Physical-Chemical and Fate Properties for Triethylene, Propylene and Dipropylene 

Glycols............................................................................................................................................ 9

Table 7– Summary of Triethylene Propylene and Dipropylene Glycols Registered Uses........... 10

Table 8 – Occupational Handler Exposure Scenarios for Triethylene, Propylene and Dipropylene 

Glycols.......................................................................................................................................... 14

Table 9 – Residential Handler Exposure Scenarios for Triethylene, Propylene and Dipropylene 

Glycols.......................................................................................................................................... 15

Table 10 – Occupational Post-Application Exposure Scenarios for Triethylene, Propylene, and 

Dipropylene Glycols..................................................................................................................... 15

Table 11 – Residential Post-Application Exposure Scenarios for Triethylene, Propylene, and 

Dipropylene Glycols..................................................................................................................... 16

Table 12 Selected Endpoints for Assessment of Propylene and Dipropylene Glycols ................ 18

Table 13 Selected Endpoints for Assessment of Triethylene Glycol ........................................... 19

Table 14 Acute Toxicity Profile of Dipropylene Glycol .............................................................. 35

Table 15 Acute Toxicity Profile of Propylene Glycol.................................................................. 36

Table 16 Acute Toxicity Profile of Triethylene Glycol ................................................................. 37

Table 17– Product Chemistry of Triethylene, Propylene and Dipropylene Glycols.................... 46

Table 18 Acute Oral Toxicity of Propylene and Dipropylene Glycol to Birds........................... 48

Table 19 Toxicity of Propylene and Dipropylene Glycol to Mammals (excerpted from Appendix 

A) .................................................................................................................................................. 49

Table 20 Acute Toxicity of Propylene and Dipropylene Glycol to Freshwater Fish .................. 49

Table 21 Acute Toxicity of Propylene/Dipropylene Glycol to Freshwater Invertebrates........... 50

Table 22 Open Literature Freshwater Invertebrate Acute Toxicity Data for Propylene Glycol . 51

Table 23 Acute Toxicity of Propylene Glycol to Inland Saltwater Lake Species....................... 51

Table 24 Chronic Toxicity of Propylene Glycol and Dipropylene Glycol to Aquatic Animals.. 52

Table 25 Toxicity of Triethylene Glycol to Mammals (excerpted from Appendix A) ............... 55

Table 26 Acute Toxicity of Triethylene Glycol to Freshwater Fish............................................ 55

Table 27 Open Literature Estuarine/Marine Fish and Invertebrate Acute Toxicity Data for 

Triethylene Glycol ........................................................................................................................ 56

Table 28 Chronic Toxicity of Triethylene Glycol to Aquatic Animals....................................... 57
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1 Introduction

This document is the Environmental Protection Agency’s (EPA or “the Agency”) Preliminary 

Work Plan (PWP) for propylene glycol, dipropylene glycol and triethylene glycol. The PWP 

document explains what EPA's Office of Pesticide Programs knows about propylene glycol, 

dipropylene glycol and triethylene glycol, highlighting anticipated data and assessment needs, 

identifying the types of information that would be especially useful to the Agency in conducting 

the review, and providing an anticipated timeline for completing the propylene glycol, 

dipropylene glycol and triethylene glycol review.

Initially, two separate Registration Review cases were scheduled to address triethylene glycol

(Case 3146) and propylene glycol and dipropylene glycol (Case 3126). However, because of 

their similar use patterns, comparable chemical, physical, and environmental fate characteristics, 

low mammalian toxicity, and low toxicity to non-target aquatic and terrestrial organisms this 

document will address propylene glycol (PC code 068603), dipropylene glycol (PC code 

068604), and triethylene glycol (PC code 083501). The agency is grouping these active 

ingredients together and merging them into the Propylene Glycol, Dipropylene Glycol and 

Triethylene Glycol Registration Review case pursuant to 40 CFR Part 155.42(a) and 40 CFR 

Part 155.42(b)(4). 

The registration review process was designed to include a public participation component to 

solicit input from interested stakeholders. The Agency intends, by sharing this information in the 

docket, to inform the public of what it knows about propylene glycol, dipropylene glycol and 

triethylene glycol and what types of new data or other information would be helpful for the 

Agency to receive as it moves toward a decision on propylene glycol, dipropylene glycol and 

triethylene glycol. The Agency encourages all interested stakeholders to review the PWP and to 

provide comments and additional information that will help the Agency’s decision-making 

process for this chemical.

1.1 Statutory and Regulatory Authority

The Food Quality Protection Act (FQPA) of 1996 mandated a registration review program. All 

pesticides distributed or sold in the United States generally must be registered by the U.S. 

Environmental Protection Agency (USEPA, EPA, or the Agency) based on scientific data 

showing that they will not cause unreasonable risks to human health or the environment when 

used as directed on product labeling. The registration review program is intended to make sure 

that, as the ability to assess risk evolves and as policies and practices change, all registered 

pesticides continue to meet the statutory standard of no unreasonable adverse effects to human 

health or the environment. Changes in science, public policy, and pesticide use practices will 

occur over time. Through the registration review program, the Agency periodically reevaluates 

pesticides to make sure that as change occurs, products in the marketplace can be used safely. 

Information on this program is provided at http://www.epa.gov/oppsrrd1/registration_review/.

The Agency is implementing the registration review program pursuant to Section 3(g) of the 

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and will review each registered 
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pesticide every 15 years to determine whether it continues to meet the FIFRA standard for 

registration. The regulations governing registration review begin at 40 CFR 155.40. The

Agency will consider benefits information and data as required by FIFRA. The public phase of 

registration review begins when the initial docket is opened for each case. The docket is the 

Agency’s opportunity to state what it knows about the pesticide and what additional risk analyses

and data or information it believes are needed to make a registration review decision. After 

reviewing and responding to comments and data received in the docket during this initial 

comment period, the Agency will develop and commit to a Final Work Plan (FWP) and 

anticipated schedule for the Propylene Glycol, Dipropylene Glycol and Triethylene Glycol Case. 

Documents associated with this registration review can be viewed at http://www.regulations.gov

in dockets EPA-HQ-OPP-2013-0218 and EPA-HQ-OPP-2013-0219. Below is a summary of the 

issues relevant to this registration review case. 

Table 1 – Summary of Anticipated Risk Assessments and Data Needs: Propylene Glycol

Risk Assessment 

Assessment 

Necessary to 

Support 

Registration 

Review

Date of 

Most 

Recent 

Assessment 

Type of 

Assessment 

Required 

(New/Updated) 

Data Anticipated as Needed

Dietary (food) No (See 3.2.1) 2/5/2007 None None

Dietary (drinking water) No (See 3.2.2) 2/5/2007 None None

Occupational Handler No (See 3.3.1) 2/5/2007 None None

Residential Handler No (See 3.3.2) 2/5/2007 None None

Residental Post 

Application No (See 3.3.3) 2/5/2007 None None

Aggregate No (See 3.4.1) 2/5/2007 None None

Cumulative No (See 3.4.2) 2/5/2007 None None 

Tolerance Review No (See 1.5.2) 2/5/2007 Updated None

Ecotoxicity No (See 4.3) 2/5/2007 None None 

Table 2 – Summary of Anticipated Risk Assessments and Data Needs: Dipropylene Glycol

Risk Assessment 

Assessment 

Necessary to 

Support 

Registration 

Review 

Date of 

Most 

Recent 

Assessment 

Type of 

Assessment 

Required 

(New/Updated) 

Data Anticipated as Needed

Dietary (food) No (See 3.2.1) 2/5/2007 None None

Dietary (drinking water) No (See 3.2.2) 2/5/2007 None None

Occupational Handler No (See 3.3.1) 2/5/2007 None None

Residential Handler No (See 3.3.2) 2/5/2007 None None

Residental Post 

Application No (See 3.3.3) 2/5/2007 None None
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Risk Assessment 

Assessment 

Necessary to 

Support 

Registration 

Review 

Date of 

Most 

Recent 

Assessment 

Type of 

Assessment 

Required 

(New/Updated) 

Data Anticipated as Needed

Aggregate No (See 3.4.1) 2/5/2007 None None 

Cumulative No (See 3.4.2) 2/5/2007 None None 

Tolerance Review Yes (See 

1.5.2) 2/5/2007 None None

Ecotoxicity No (See 4.3) 2/5/2007 None None 

Table 3 – Summary of Anticipated Risk Assessments and Data Needs: Triethylene Glycol

Risk Assessment 

Assessment 

Necessary to 

Support 

Registration 

Review 

Date of 

Most 

Recent 

Assessment 

Type of 

Assessment 

Required 

(New/Updated) 

Data Anticipated as Needed 

Dietary (food) No (See 3.2.1) 1/25/2006 None None

Dietary (drinking water) No (See 3.2.2) 1/25/2006 None None

Occupational Handler No (See 3.3.1) 1/25/2006 None None

Residential Handler No (See 3.3.2) 1/25/2006 None None

Residental Post 

Application No (See 3.3.3) 1/25/2006 None None

Aggregate No (See 3.4.1) 1/25/2006 None None 

Cumulative No (See 3.4.2) 1/25/2006 None None 

Tolerance Review No (See 1.5.2) 1/25/2006 None None

Ecotoxicity No (See 4.3) 1/.25/2006 None None 

Table 4 – Anticipated Registration Review Schedule

Anticipated Activity Target Date* Completion Date

Phase 1: Opening the Docket 

Open Docket and 60-Day Comment Period for Preliminary Work Plan 2013-06 2013-06-20

Close Public Comment Period 2013-08

Phase 2: Case Development 

Issue Final Work Plan 2013-12

Issue Data Call-In (DCI) N/A

Receive Data to be Considered in Risk Assessment N/A

Open 30-Day Public Comment Period for Preliminary Risk Assessment(s) N/A

Close Public Comment Period N/A

Phase 3: Registration Review Decision and Implementation 

Open 60-Day Public Comment Period for Proposed Decision 2014-12

Close Public Comment Period 2015-02

Issue Final Decision 2015-06

Begin Post-Decision Followup 2016-01
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Anticipated Activity Target Date* Completion Date

Total (years) 2.5

*The anticipated schedule will be revised as necessary (e.g., need arising under the Endocrine Disruptor Screening Program with 

respect to the active ingredients in this case).

1.2 Case Overview

The docket for the propylene glycol, dipropylene glycol and triethylene glycol Case (Case 3126 

& 3146) has been established at http://www.regulations.gov in docket numbers EPA-HQ-OPP2013-0218 and EPA-HQ-OPP-2013-0219.

Initially, separate Registration Review cases were scheduled to address triethylene glycol (Case 

3146) and propylene glycol and dipropylene glycol (Case 3126). However, because of their 

similar use patterns, comparable chemical, physical, and environmental fate characteristics, low 

mammalian toxicity and low toxicity to non-target aquatic and terrestrial organisms, this 

document will address propylene glycol (PC code 068603), dipropylene glycol (PC code 

068604), and triethylene glycol (PC code 083501). The agency is grouping these active 

ingredients together and merging them into the Propylene Glycol, Dipropylene Glycol and 

Triethylene Glycol Registration Review Case.

According to the 2011-2014 public Registration Review schedule, cases 3146 and 3126 were 

planned to begin in fiscal year 2013. To ensure the public is able to locate information 

associated with case 3146 and case 3126, EPA has created and will maintain a separate docket

for each case. All EPA documents relevant to the two cases will be posted in the two dockets.

This case will be referred to as the Propylene Glycol, Dipropylene Glycol and Triethylene 

Glycol Case. As a result of this grouping and merger, the Propylene Glycol, Dipropylene Glycol 

and Triethylene Glycol Case will now include:

1. Case 3146: triethylene glycol (PC code 083501);

2. Case 3126: propylene glycol (PC code 068603) and dipropylene glycol (PC code 

068604)

1.3 Chemical Identification and Properties

Table 5 presents the active ingredients to be assessed in Case 3146: triethylene glycol (PC Code 

083501); and Case 3126: propylene glycol (PC Codes 068603) dipropylene glycol (PC Code 

068604). 

Table 5- Chemical Identification of Triethylene, Propylene and Dipropylene Glycols

Common 

Name Triethylene Glycol Propylene Glycol Dipropylene Glycol

Classification

Glycol

Dihydroxy alcohols

Oxygenated Hydrocarbon

Glycol

Dihydroxy alcohols

Glycol

Dihydroxy alcohols

Oxygenated hydrocarbon

Case # 3146 3126 3126
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Common 

Name Triethylene Glycol Propylene Glycol Dipropylene Glycol

PC Code 083501 068603 068604

CAS No. 112-27-6 57-55-6 25265-71-8 

Case No. 3146 3126 3126

Molecular 

Formula C6H14O4 C3H8O2 C6H14O3

Molecular 

Weight 150.17 g/mol 76.09 g/mol 134.20 g/mol 

Molecular 

Structure:

Triethylene glycol, propylene glycol and dipropylene glycol product chemistry information

relevant to the risk assessment is summarized in Table 6 and more detailed product chemistry 

information is provided in Appendix B. Sources of information used to construct Table 6 consist 

of MRIDs 42814401, 42814402, 42814403, 43178601, 43178603, 43179501, 43179502, 

43179503, and EPI Suite v4.1.

Table 6– Physical-Chemical and Fate Properties for Triethylene, Propylene and 

Dipropylene Glycols

Guideline 

No. Property Triethylene Glycol Propylene Glycol Dipropylene Glycol

830.7000 pH 6.0 - 9.5 Neutral Neutral

830.7050 UV/Visible 

Absorption

Does not absorb light at 

wavelengths >290 nm 

and therefore it is not 

expected to be susceptible 

to direct photolysis by 

sunlight.

Does not absorb light at 

wavelengths >290 nm and 

therefore it is not expected 

to be susceptible to direct 

photolysis by sunlight.

Does not absorb light at 

wavelengths >290 nm and 

therefore it is not expected 

to be susceptible to direct 

photolysis by sunlight.

830.7200 

Melting point:

Freezing point:

Not applicable. Product is 

liquid at room 

temperature.

−4.3°C to −7 °C

Not applicable. Product is 

liquid at room 

temperature.

−59°C

Not applicable. Product is 

liquid at room 

temperature.

−59°C

830.7220 Boiling point 288.0°C at 760 mm Hg. 188 °C at 760 mm Hg 230 oC at 760 mm Hg

830.7300 Density 1.1255 g/mL at 25°C 1.032 g/ mL at 25°C 1.022 g/ mL at 25oC

830.7370 Dissociation 

Constant (pKa)

Not applicable. Does not 

dissociate in water.

Not applicable. Does not 

dissociate in water.

Not applicable. Does not 

dissociate in water.

830.7550 Partition coefficient

(Log Kow) −1.75 − 0.92 − 0.67

830.7840 Solubility in water Completely soluble. Completely soluble. Completely soluble.

830.7950 Vapor pressure

(at 25°C) 1.32 x10-3 mm Hg 1.3 x10-1 mm Hg 1.6 x10-2 mm Hg 

Henry law constant 

(atm-m3/mole) 3 x 10-11 1.29 x 10-8 6.58 x 10-13

Ready 

Biodegradation YES YES YES

Stability in air 

(hours) 3.5 10 4
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Guideline 

No. Property Triethylene Glycol Propylene Glycol Dipropylene Glycol

Koc (L/kg) 0.089 1 0.45

NG STP removal (%) ~ 2 ~ 2 ~ 2

NG Effluent (%) 98 98 98

NG: non-guideline information

1.4 Use/Usage Description

1.4.1 Registrations

There are two EPA-registered products that contain propylene glycol as an active ingredient 

(a.i.). The percent a.i. in both products is 4.4% and the formulations include pressurized liquids 

in aerosol cans and automatic aerosol dispenser. There is no propylene glycol manufacturing use 

product.

There are two EPA-registered products that contain dipropylene glycol as an a.i. The percent a.i. 

in the products is 4.4% and 5.31% and the formulations include pressurized liquids in aerosol 

cans and automatic aerosol dispenser. There is no dipropylene glycol manufacturing use 

product.

There are 18 EPA-registered products that contain triethylene glycol as an a.i. The percent a.i. 

ranges from 0.05% to 86% and the formulations include pressurized liquids in aerosol cans, 

automatic aerosol dispenser, and total release foggers. There is no triethylene glycol 

manufacturing use product.

1.4.2 Summary of Registered Uses

Table 7 presents a summary of the registered uses of triethylene glycol, propylene glycol and 

dipropylene glycol that will be assessed in this registration review. Triethylene, propylene and 

dipropylene glycols can be applied by the following application methods: aerosol can, automatic 

aerosol dispenser, and total release fogger.

Table 7– Summary of Triethylene Propylene and Dipropylene Glycols Registered Uses

Use Application Method Application 

Rate

Commercial, Industrial, Institutional, Premises and Equipment

Space spray and surface treatment Aerosol can and automatic aerosol dispenser See footnote1

Food Handling/Storage Establishments Premises and Equipment2

Space spray and surface treatment Aerosol can and automatic aerosol dispenser See footnote1

Residential and Public Access Premises

Aerosol, fog, space spray and surface Aerosol can, automatic aerosol dispenser, and total See footnote1

 1 Many of the aerosol labels specify a surface spray to spray until completely wet for 10 minutes; many labels 

specify to spray upward in center of room for 3-10 seconds in a room of average size 12 by 12 feet. 2 Dipropylene glycol is the only chemical in this case that has currently registered food uses.
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treatment release fogger

Medical/Dental/Veterinary Premises and Equipment

Space spray and surface treatment Aerosol can and automatic aerosol dispenser, See footnote1

1.4.3 Usage Information 

Usage information is not available for the propylene glycol, dipropylene glycol or triethylene 

glycol. The Kline Biocides Report for 2004/2005 (Kline, 2005) does not include propylene 

glycol, dipropylene glycol or triethylene glycol.

1.5 Regulatory History 

Propylene glycol and dipropylene glycol were first registered in 1950 and 1959, respectively, for 

use in hospitals as air disinfectants. The Agency completed a Reregistration Eligibility Decision 

(RED) for propylene glycol and dipropylene glycol in 2006.

Triethylene glycol was first registered in 1947 for use in hospitals as an air disinfectant. The 

Agency completed a RED for triethylene glycol in 2003.

1.5.1 Recent/Pending Regulatory Actions 

There are no recent regulatory actions for propylene glycol, dipropylene glycol or triethylene 

glycol.

1.5.2 Tolerance Information 

EPA has not established a tolerance or tolerance exemption for residues of propylene glycol, 

dipropylene glycol or triethylene glycol in food resulting from registered uses as an active 

ingredient. Based on the current uses for dipropylene glycol, the agency has identified the need 

to establish a tolerance and/or exemption from the requirement of a tolerance in 40 CFR Section 

180. As part of this registration review, EPA intends to establish the appropriate tolerance and/or 

exemption in response to the petitions expected to be received from registrants supporting the 

following uses for dipropylene glycol: hard nonporous food service use sites. Triethylene glycol 

and propylene glycol are not used as active ingredients in currently registered food use products. 

Therefore, tolerances and/or exemptions are not needed for triethylene glycol and propylene 

glycol. EPA has established exemptions from the requirement of a tolerance when propylene 

glycol is used as an intentionally-added inert ingredient (solvent or cosolvent) in pesticide 

formulations (40 CFR 180.910 and 180.930). Dipropylene glycol has been exempted from the 

requirement of a tolerance when used as an intentionally-added inert ingredient (solvent or 

cosolvent) in pesticide formulations (40 CFR 180.910). Triethylene glycol is exempted from the 

requirement of a tolerance when used as an intentionally-added inert ingredient (deactivator) in 

pesticide formulations (40 CFR 180.920). Propylene glycol has been classified as Generally 

Recognized as Safe (GRAS) by FDA in association with several uses: as an emulsifying agent 

(21 CFR 582.4666), as a general purpose food additive (21 CFR 582.1666), and as a direct food 

additive (21 CFR 184.1666). Dipropylene glycol and triethylene glycol are the subject of the 
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following indirect food additive regulations: components of adhesives (21 CFR 175.105), 

components of paper and paperboard in contact with aqueous and fatty foods (21 CFR 176.170), 

surface lubricants used to make metallic food contact articles (21 CFR 178.3910), defoaming 

agent used in coatings (176.200), as a component of cellophane (21 CFR 177.1200), in 

packaging materials for food to be irradiated (21 CFR 179.45), as components of resinous and 

polymeric coatings (21 CFR 175.300), as adjuvants and production aids as plasticizers in 

polymeric substances (21 CFR 178.3740), and as an optional adjuvant in resinous and polymeric 

coatings for polyolefin films. No Food Contact Substance Notifications (FCNs) have been 

determined to be effective by FDA for propylene glycol, dipropylene glycol or triethylene 

glycol. 

1.6 Incidents

1.6.1 Human Health 

No reports of incidents associated with human exposure to propylene glycol and/or dipropylene 

glycol have been reported in the OPP Incident Data System during the time period from 2001to

2012.

However, for triethylene glycol, there are 413 incidents which have been reported in the OPP 

Incident Data System (2001 – 2012) which have been specifically associated with exposure to 

triethylene glycol. However, triethylene glycol is a high production volume chemical with

approximately 5,000,000 pounds produced from 2004 to 2012 for pesticide products. Given the 

high production volume of the chemical and the 11 year period of which incidents occurred, the

number of incidents is not unusual. Inhalation exposure is the primary exposure route in these 

reported cases followed by dermal exposure. Most of the incidents are related to inhalation 

irritation and/or allergic-type reaction. For inhalation exposure incidents, the reported symptoms 

include respiratory irritation, coughing, chest tightness, difficulty breathing, shortness of breath 

and wheezing. For dermal exposure, blisters, hives, welts, rash, and bleeding have been 

reported. In addition, ocular irritation and fever have also been reported.

1.6.2 Ecological

No ecological incidents reported for triethylene glycol, propylene glycol and dipropylene glycol 

from 2001-2012 (IDS).

2 Anticipated Data Needs

No data are anticipated to be needed to support a human health or environmental risk assessment 

for the triethylene glycol, propylene glycol and dipropylene glycol registration review.

3 Human Health Risk Assessment

The agency does not anticipate the need to conduct a human health risk assessment for 

triethylene, propylene and dipropylene glycols. The agency does not expect to require additional 

data for use in conducting the registration review. According to the triethylene glycol RED and 

propylene and dipropylene glycol RED, potential for dermal, inhalation, or incidental ingestion
Page 13 of 58

exposure may occur during application of the glycols as well as post-application following use of 

glycols may occur following air sanitization, hard surface disinfection and direct use on pets. 

However, there is no evidence of adverse effects at doses of triethylene glycol, propylene glycol 

or dipropylene glycol up to the established limit dose in repeat-exposure dermal (1000 

mg/kg/day) and inhalation (1 mg/L or 1000 mg/m3

) toxicity studies. Thus, no toxicological 

endpoints of concern have been established for either of these chemicals based on review of the 

available mammalian toxicity data. Due to the low order of toxicity and low application rates 

from the current uses of these chemicals, no risks associated with potential exposures have been 

quantified for use of triethylene glycol, propylene glycol or dipropylene glycol as active 

ingredients in pesticide products. 

3.1 Existing Toxicological Endpoints 

In the September 2006 Propylene Glycol and Diproylene Glycol RED and the September 2003 

Triethylene Glycol RED, the Agency concluded that propylene glycol, dipropylene glycol, and 

triethylene glycol pose no toxicological concerns due to their low toxicity; therefore, no 

toxicological endpoints of concern were developed. Based on a review of the available toxicity 

data (see Appendix A), the agency concludes that for registration review these chemicals pose no 

toxicological concerns when used according to pesticide labeled uses. No additional toxicity 

data requirements are anticipated at this time for registration review. This conclusion is based on 

the results of toxicity testing of propylene glycol and dipropylene and triethylene glycol at dose 

levels near or above testing limits (as established in the OPPTS 870 series harmonized test 

guidelines). No significant toxicity was observed in any of the animal toxicity studies in the 

existing toxicological database for registration review. A detailed description of the toxicity 

studies for triethylene glycol, propylene glycol and dipropylene glycol for registration review is 

provided in Appendix A .

3.2 Dietary Exposure

3.2.1 Food 

Although human dietary exposure to the subject glycols could potentially occur as a result of the 

registered uses, there is no risk associated with these related compounds because they do not 

induce adverse systemic effects except at doses much higher than could be expected from 

pesticidal uses (EPA 2013a and 2013b). As part of this registration review, EPA intends to 

establish the appropriate tolerance and/or exemption in response to the petitions expected to be 

received from registrants supporting the following uses for dipropylene glycol: hard nonporous 

food service use sites. Triethylene glycol and propylene glycol are not used in currently 

registered food use products. Therefore, tolerances and/or exemptions are not needed for 

triethylene glycol and propylene glycol. 

3.2.2 Drinking Water

Although human dietary exposure via drinking water to the glycols may occur as a result of the 

registered uses, there is no risk associated with these related compounds because they do not 

induce adverse systemic effects except at doses much higher than could be expected from 

pesticidal uses (EPA 2013a and 2013b). Therefore, no additional data are anticipated to be 
Page 14 of 58

needed and dietary risk assessments reflecting exposures to the glycols in drinking water are not 

expected to be necessary.

3.3 Occupational and Residential Exposures

The agency does not anticipate that a new occupational and residential risk assessment will be 

needed based on the lack of toxicological endpoints. No toxicological endpoints of concern have 

been established for either of these chemicals based on review of the available mammalian 

toxicity data. Due to the low order of toxicity and low application rates from the current uses of 

these chemicals, no risks associated with potential exposures have been quantified for use of 

triethylene glycol, propylene glycol or dipropylene glycol as active ingredients in pesticide 

products. The earlier risk assessments for propylene and dipropylene glycol completed in 

February 5, 2007 and triethylene glycol on May 24, 2005 do not need to be updated (EPA 2007a 

and EPA 2005).

3.3.1 Occupational Handler Exposure

The agency does not anticipate the need to revise the occupational handler assessments that were 

already conducted during reregistration. Although there is potential for occupational dermal 

and/or inhalation exposure, no toxicological endpoints of concern were identified. Therefore no 

risk assessments can be conducted or are anticipated as needed. 

Potential exposure may occur during application of the glycols as well as post-application 

following air sanitization, hard surface disinfection, and direct use on pets. No chemical-specific 

handler data were submitted to estimate the potential exposures associated with these uses of 

triethylene, propylene and dipropylene glycol (nor are they anticipated as needed at this time

since a risk assessment cannot be conducted without toxicological endpoints). 

Table 8 – Occupational Handler Exposure Scenarios for Triethylene, Propylene and 

Dipropylene Glycols

Scenario Exposure 

Route(s) Duration

Occupational Exposures

Applying disinfectant spray to hard surfaces and the air using an

aerosol can Dermal /Inhalation Short, Intermediate, and Long Term

Applying disinfectant spray to the air using an automatic aerosol 

dispenser Inhalation Short, Intermediate, and Long Term

Applying disinfectant to the air using total release foggers or misters Inhalation Short and Intermediate Term

3.3.2 Residential Handler Exposures

EPA does not anticipate the need to revise the residential handler assessment conducted in 

support of reregistration. Potential for residential dermal and/or inhalation exposure may occur 

during application of the glycols as well as post-application following air sanitization, hard 

surface disinfection, and direct use on pets. No chemical-specific handler data were submitted to 

estimate the potential exposures associated with these uses of triethylene, propylene and 

dipropylene glycol (nor are they anticipated as needed at this time since a risk assessment cannot 
Page 15 of 58

be conducted without toxicological endpoints). However, because no toxicological endpoints of 

concern were identified, the exposures have not been quantified and no handler data were 

required in the RED and none are anticipated as needed for registration review.

Table 9 – Residential Handler Exposure Scenarios for Triethylene, Propylene and 

Dipropylene Glycols

Scenario Exposure Route(s) Duration

Residential Exposures

Applying disinfectant spray to hard surfaces and the air using an

aerosol can Dermal /Inhalation Short and Intermediate Term

Applying disinfectant spray to the air using an automatic aerosol 

dispenser Inhalation Short and Intermediate

Applying disinfectant to the air using total release foggers or misters Inhalation Short and Intermediate 

Term

3.3.3 Occupational Post-Application Exposures

Potential for occupational post application exposure may occur to individuals reentering treated 

rooms and/or contacting sprayed surfaces. Disinfectant properties are utilized in the household 

for hard, nonporous surfaces including windows, shower stalls, countertops, refrigerators, 

microwave ovens, and tubs (i.e., non-food contact surfaces). As an air sanitizer, this active 

ingredient has numerous listed active use sites including industrial/institutional use in 

washrooms, auditoriums, public rooms, hotel lobbies, theaters, hospitals, classrooms, railroads, 

airplanes, buses, taxicabs, sitting rooms, locker rooms, factories, mills, and department stores. 

However, because no toxicological endpoints of concern were identified, the exposures have not 

been quantified and no post application data were required during reregistration and none are 

anticipated as needed for registration review.

Table 10 – Occupational Post-Application Exposure Scenarios for Triethylene, Propylene, 

and Dipropylene Glycols

Scenario Exposure 

Route(s) Duration

Post application exposure bystanders to aerosols and vapors released from 

air deodorizing treatments Inhalation Short and Intermediate Term

3.3.4 Residential Post-Application Exposures

Potential for residential post application exposure may occur to individuals reentering treated 

rooms and/or contacting sprayed surfaces. Disinfectant properties are utilized in the household 

for hard, nonporous surfaces including windows, shower stalls, countertops, refrigerators, 

microwave ovens, and tubs (i.e., non-food contact surfaces). Children could become exposed to 

residues from hand-to-mouth or from dermal contact. As an air sanitizer, this active ingredient 

has numerous listed active use sites in bathrooms. However, because no toxicological endpoints 

of concern were identified, the exposures have not been quantified and no post application data 

were required during reregistration and none are anticipated as needed for registration review.
Page 16 of 58

Table 11 – Residential Post-Application Exposure Scenarios for Triethylene, Propylene, 

and Dipropylene Glycols

Scenario Exposure Route(s) Duration

Postapplication exposure to children from dermal and hand-to-mouth 

contact from treated floors.

Incidental 

ingestion/dermal

Short and Intermediate 

Term

Post application exposure bystanders to aerosols and vapors released 

from air deodorizing treatments Inhalation Short and Intermediate 

Term

3.4 Aggregate and Cumulative Exposure

3.4.1 Aggregate Exposures

In examining aggregate exposure, EPA takes into account the available and reliable information 

concerning exposures to pesticide residues in food and drinking water, and non-occupational 

pesticide exposures. An aggregate risk assessment cannot be conducted because toxicological

endpoints for propylene glycol, dipropylene glycol, and triethylene glycol have not been

established.

3.4.2 Cumulative Exposures

Unlike other pesticides for which EPA has followed a cumulative risk approach based on a 

common mechanism of toxicity, EPA has not made a common mechanism of toxicity finding as 

to propylene glycol, dipropylene glycol, and triethylene glycol and any other substances . For 

information regarding EPA’s efforts to determine which chemicals have a common mechanism 

of toxicity and to evaluate the cumulative effects of such chemicals, see the policy statements 

released by EPA’s Office of Pesticide Programs concerning common mechanism determinations 

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

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

4 Environmental Risk Assessment

The agency does not anticipate the need to conduct an environmental risk assessment for 

triethylene glycol, propylene glycol and dipropylene glycol because the indoor air and surface 

disinfection uses with the given application methods are not expected to result in exposure of 

terrestrial or aquatic organisms. No changes to the use patterns have occurred for the glycols 

since the Propylene and Dipropylene Glycol RED or the Triethylene Glycol RED (See Section 

1.5.1). There are new models and approaches that the agency has been implementing since the 

publication of these REDs. Application methods using aerosol cans, automatic aerosol 

dispensers, and foggers are not expected to result in down-the-drain disposal and there is no 

direct exposure to non-target organisms. The agency does not anticipate requiring additional 

data for this registration review.

4.1 Environmental Fate Assessment

The Agency does not anticipate requiring additional environmental fate data at this time because 

triethylene glycol, dipropylene glycol and propylene glycol are not persistent in the environment. 
Page 17 of 58

In 2003, the Agency issued an Ecological Risk Assessment for triethylene glycol which 

concluded: “Triethylene glycol is miscible in water, mobile in soils, and stable to abiotic 

hydrolysis, as well as soil and aquatic photolysis. River dye-away tests indicate that triethylene 

glycol degrades in soils from a few days to weeks. It undergoes ready biodegradation, according 

to the activated sludge studies.” In 2006, the Agency completed an Ecological Risk Assessment 

for propylene glycol and dipropylene glycol. In its fate assessment, the Agency concluded that “ 

Propylene glycol and dipropylene glycol are miscible in water, mobile in soils, have low 

absorptivity to soil, and are stable to abiotic hydrolytic degradation as well as it does not undergo 

abiotic photodegradation in soil and in water. However, in aerobic soils propylene glycol 

biodegrades to carbon dioxide (CO2) in 4 days, whereas biodegradation of dipropylene glycol 

may be a slightly slower process according to biological (biodegradability) screening tests. 

However, this process may still be an important mechanism for removal of dipropylene glycol 

from aerobic soils.” The physical and chemical properties and fate data are summarized in Table 

6.

The low Kow of -1.75, -0.92 and -0.67 for triethylene glycol, propylene glycol and, dipropylene 

glycol, respectively, are not likely to bioaccumulate in aquatic organisms. With a vapor pressure 

of 0.00132 mmHg at 25 oC, 0.13 mm Hg and 1.6 x10-2 mm Hg at 25 oC, for triethylene glycol,

propylene glycol and dipropylene glycol, respectively, these glycols would exist in large part in 

the vapor phase in the atmosphere but degrade rapidly (half-life approximately between 3.5 to 10 

hours) by reaction with photo-chemically produced hydroxyl radicals. Therefore, the presence of 

triethylene glycol, propylene glycol, dipropylene glycol in the environment, including the 

atmosphere, will be transient and not persistent.

Additional fate parameters obtained from the Agency’s EPI Suite v 4.1 estimation program 

indicate that these glycols have low Koc values of 1, 0.45 and 0.089 which make them have a 

high mobility in soils; but as observed earlier, these glycols degrade fast in soils. All three 

glycols are ready biodegradable and dye-away testing shows these glycols have a tendency to 

mineralize within a few days to two weeks. Because of their high solubility in water from 811 to 

1000 g/L, these glycols will not likely be adsorbed to sediments. The Agency does not anticipate 

requiring additional environmental fate data at this time for this registration review.

4.2 Conceptual Models for Environmental Exposure Pathways

All registered pesticide uses of propylene glycol, dipropylene glycol and triethylene glycol as 

active ingredients are considered to have no exposure to non-target organisms. The indoor air 

and surface disinfection using aerosol cans, automatic aerosol dispensers, and foggers as 

application methods are not expected to result in down-the-drain disposal and as a result, there is 

no direct exposure to non-target organisms. The lack of exposure means, except for spills or 

accidental releases, there is no ecological risk of concern from their use. 

4.3 Ecological Effects Assessment

4.3.1 Mechanism of Action

Propylene glycol, dipropylene glycol and triethylene glycol are all alcohols and dipropylene 

glycol and triethylene glycol are also esters. They inactivate target pests by denaturing proteins 

found in cell membranes and viral protein coats. This leads to the target pests losing structural 
Page 18 of 58

integrity and losing the ability to cause infections (USEPA, 2004, 2006b). For non-target aquatic 

animals, these chemicals act acutely by narcosis, a non-specific mechanism of action.

4.3.2 Measures of Effect (Ecotoxicology Endpoints)

Propylene glycol and dipropylene glycol show very low acute toxicity to terrestrial and aquatic 

animals (Table 12 and Appendix C). The toxicity endpoints presented below are based on the 

results of toxicity studies submitted by registrants to meet the Agency’s ecological effects data 

requirements for the uses of propylene glycol and dipropylene glycol. Additional information 

was located in EPA/ORD’s ECOTOX database, which provides summary endpoints from the 

open scientific literature as well as studies submitted to the Agency. For missing data, the 

structure activity program ECOSAR v1.10 was used to estimate endpoint values. While 

ECOSAR v1.10 provided estimates for chronic fish and invertebrate endpoints, these results,

while in Appendix C, are not in Table 12 because they are not required for the assessment.

Table 12 Selected Endpoints for Assessment of Propylene and Dipropylene Glycols

Receptor Group Surrogate 

Species

Risk

Scenario

Toxicity

Endpointa

Reference

(MRID)

Birds

Northern 

bobwhite 

quail

Acute oral LD50>2,000 mg/kg-bw 43762301

43760607

Subacute dietary Data not required --

Chronic Data not required --

Mammals Rat Acute LD50 >5,000 mg/kg-bw See Appendix A

Chronic Data not required

Freshwater fish Fathead 

minnow

Acute 96-hr LC50 = 790 ppm propylene 

glycol

ECOSAR v1.10 See 

Appendix C

Chronic Data not required --

Freshwater

invertebrates Waterflea Acute 48-hr EC50 > 100 ppma Several MRIDs see 

Appendix C

Chronic Data not required --

Estuarine/marine 

fish Generic fish Acute 96-hr LC50 > 24,000 ppma ECOSAR v1.10 See 

Chronic Data not required Appendix C

Estuarine/marine

invertebrates

Eastern 

Oyster Acute Data not required --

Mysid Acute 96-hr LC50 >100,000 ppma ECOSAR v1.10 See 

Chronic Data not required Appendix C

Aquatic Plants Green algae Nonlisted species 96-hr IC50 >5,000 ppma ECOSAR v1.10 See 

Listed Species 96-hr Chv >300 ppm Appendix C a

a For definitive values see Appendix C. Non-definitive values are provided in the table to show that both chemicals 

have low toxicity, and are considered potentially non-toxic. For the propylene and dipropylene gylcol uses, green 

algae data and acute animal data were required only for hazard labeling purposes. No risk assessment is anticipated.

Triethylene glycol show very low acute toxicity to terrestrial and aquatic animals (Table 13 and 

Appendix D). The toxicity endpoints presented below are based on the results of toxicity studies 

submitted by registrants to meet the Agency’s ecological effects data requirements for the uses of 

triethylene glycol. Additional information was located in EPA/ORD’s ECOTOX database, 

which provides summary endpoints from the open scientific literature as well as studies 

submitted to the Agency. For missing data, the structure activity program ECOSAR v1.10 was 

used to estimate endpoint values. However, the ECOSAR v1.10 neutral organics model may not 

be appropriate for triethylene gylcol. Estimates of acute values were higher than actual 
Page 19 of 58

laboratory studies in some cases. While ECOSAR v1.10 provided estimates for chronic fish and 

invertebrate endpoints, these results, while in Appendix D, are not in Table 13 because they are 

not required for the assessment.

Table 13 Selected Endpoints for Assessment of Triethylene Glycol

Receptor Group Surrogate 

Species

Risk

Scenario

Toxicity

Endpointa

Reference

(MRID)

Birds

Northern 

bobwhite 

quail

Acute oral None None

Subacute dietary Data not required --

Chronic Data not required --

Mammals Rat Acute LD50 = 15,000 mg/kg-bw See Appendix A

Chronic Data not required

Freshwater fish Bluegill 

sunfish

Acute 96-hr LC50 = 10,000 ppm Verschuren, 1983

Chronic Data not required --

Freshwater 

invertebrates Waterflea Acute 48-hr EC50 =116,000 ppma ECOSAR v1.10 See 

Appendix D

Chronic Data not required --

Estuarine/marine 

fish

Inland 

Silverside

Acute 96-hr LC50 = 10,000 ppm Verschuren, 1983 Chronic Data not required

Estuarine/marine 

invertebrates

Eastern 

Oyster Acute Data not required --

Mysid Acute 96-hr LC50 = 11,000 ppm 40228401 Chronic Data not required

Aquatic Plants Green algae Nonlisted species 96-hr IC50 = 67,640 ppm ECOSAR v1.10 See 

Listed Species 96-hr Chv = 2,486 ppm Appendix C

4.4 Exposure Analysis Plan

4.4.1 Aquatic and Terrestrial Wildlife Exposure Estimates

Since the agency does not anticipating conducting an environmental risk assessment, no 

exposure analysis plan is needed. The agency does not anticipate exposure of aquatic and 

terrestrial organisms.

4.5 Effects Analysis Plan

Since the agency does not anticipating conducting an environmental risk assessment, no effects 

analysis plan is needed.

4.5.1 Endangered Species Effects Determination

Based on the low likelihood of exposure of triethylene glycol, dipropylene glycol and propylene 

glycol in various environmental media like water, soils, and air, the Agency intends to conclude 

that the registered uses of triethylene glycol, dipropylene glycol and propylene glycol will have 

'no effect' on endangered or threatened terrestrial or aquatic species, or their designated critical 

habitats, as listed by the U.S. Fish and Wildlife Service (USFWS) and the National Oceanic and 

Atmospheric Administration's (NOAA) National Marine Fisheries Service (NMFS). EPA 

anticipates conducting no further analysis of potential risks to endangered or threatened species 
Page 20 of 58

unless public comment or other submissions provide data or information that would otherwise 

inform the Agency's determination. However, the Agency will review any comments made by 

the public on this document and will conduct an environmental risk assessment if new 

information warrants such action. 

5 Endocrine Disruptor Screening Program (EDSP)

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 reregistration decision, for propylene glycol, dipropylene glycol 

and triethylene glycol, 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), propylene glycol, dipropylene glycol and triethylene glycol are 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. 

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. Propylene glycol, 

dipropylene glycol and triethylene glycol are not among the group of 58 pesticide active 

ingredients on the initial list to be screened under the EDSP. Accordingly, as part of registration 

review, EPA will issue future EDSP orders/data call-ins, requiring the submission of EDSP 

screening assays for propylene glycol, dipropylene glycol and triethylene glycol.

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

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

website: http://www.epa.gov/endo/. 
Page 21 of 58

6 Guidance for Commenters

6.1 Preliminary Work Plan 

The public is invited to comment on EPA’s Preliminary Work Plan and rationale. The Agency 

will carefully consider all comments as well as any additional information or data provided in a 

timely manner prior to issuing a final work plan for the Propylene Glycol, Dipropylene Glycol 

and Triethylene Glycol registration review case. 

6.1.1 Trade Irritants 

Through the registration review process, the Agency intends to solicit information on trade 

irritants and, to the extent feasible, take steps toward facilitating irritant resolution. The Agency 

will work to harmonize tolerances and international maximum residue limits (MRLs) and may 

modify tolerance levels to do so, when possible. Stakeholders are asked to comment on any 

trade irritant issues resulting from lack of MRLs or disparities between U.S. tolerances and 

MRLs in key export markets, providing as much specificity as possible regarding the nature of 

the concern.

6.1.2 Water Quality 

Glycols, specifically ethylene glycol and propylene glycol (one of the three glycols in the present 

case) are identified as a cause of impairment of Yeader Creek, Polk County in Des Moines, 

Iowa. This water body is listed as impaired under section 303(d) of the Clean Water Act3. 

Yeader Creek is across the Des Moines International Airport where the use of ethylene glycol for 

deicing of planes occurs. All sites listed for pesticides and organics were reviewed and only this 

site was identified as impaired. Total Maximum Daily Load (TMDL) for Des Moines 

International Airport to Yeader Creek for ethylene glycol was: 125 mg/L (30-day average), and 

190 mg/L for daily maximum. TMDL for propylene glycol was: 100 mg/L (30-day average), 

and 150 mg/L for the daily maximum. Effects on benthic macroinvertebrates were recognized as 

the biological target (Index of Biotic Integrity (IBI) = 43a4). However, the impairment was due 

to a non-pesticidal use of propylene glycol. 

More information on impaired water bodies and TMDLs can be found at EPA’s website5. The 

Agency invites submission of water quality data for this pesticide. To the extent possible, 

data should conform to the quality standards in Appendix A of the OPP Standard Operating 

Procedure: Inclusion of Impaired Water Body and Other Water Quality Data in OPP’s 

Registration Review Risk Assessment and Management Process6 in order to ensure they can be 

used quantitatively or qualitatively in pesticide risk assessments.

 3 http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885 4 TMDL for Priority Organics, Yeader Creek, Polk County, 2005

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

6 http://www.epa.gov/oppsrrd1/registration_review/water_quality_sop.htm
Page 22 of 58

6.1.3 Environmental Justice

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

people, regardless of race, color, national origin, or income, in the development, implementation, 

and enforcement of environmental laws, regulations, and policies. To help address potential 

environmental justice issues, the Agency seeks information on any groups or segments of the 

population who, as a result of their location, cultural practices, or other factors, may have 

atypical, unusually high exposure to propylene glycol, dipropylene glycol and triethylene glycol 

compared to the general population. Please comment if you are aware of any sub-populations 

that may have atypical, unusually high exposure compared to the general population.

6.1.4 Structure Activity Relationships 

EPA must rely upon information of appropriate quality and reliability for each decision made by 

the Agency. In the Office of Pesticide Programs (OPP), the evaluation process for a pesticide 

chemical traditionally begins with the applicant’s submission of a set of studies conducted with 

the specific pesticide chemical of interest. The use of the results of such testing (measured data) 

is a logical, scientifically rigorous process that identifies the physical, chemical, and 

environmental fate properties of the pesticide, as well as the dose and endpoints at which an 

adverse effect can occur in various animal species. 

Today, there is significant interest in alternative techniques, i.e., techniques other than data 

generation that could significantly inform the Agency’s decision-making process. Recently, OPP 

has made increasing use of structure activity relationship (SAR) as part of its regulatory 

decision-making process. In the SAR process, a chemical's molecular structure is compared to 

that of other chemicals for which data are available. These structural similarities are then used to 

make predictive judgments about a chemical’s physical, chemical, and biological properties. 

Thus, the chemical’s physical, chemical, and biological properties are a function of (or directly 

related to) the chemical’s molecular structure. Quantitative SAR is referred to as QSAR. To 

develop a QSAR, a selected set of measured data on a single physical, chemical, or biological 

property is used to derive a model (an equation) to predict the value of that property. 

Since SAR assessments and QSAR modeling are another set of tools that are available to Agency 

scientists, OPP has begun a process shift that envisions shifting from the current study-by-study 

approach to an approach in which the use of predicted data, generated using validated models, is 

considered along with information from open literature and studies specifically generated under 

Part 161 requirements. All relevant information would be considered as part of a weight-of-theevidence evaluation. 

At this time, EPA believes that for certain endpoints, especially physical/chemical and fate 

properties, that SAR and QSAR might be effectively utilized to fulfill these data requirements 

for many antimicrobial pesticide chemicals. When considering biological properties, at this time, 

EPA believes that SAR and QSAR can be most effectively utilized in the evaluation of 

chemicals that exhibit lower toxicity for human health and/or ecotoxicity parameters. This is 

appropriate because the risk assessment for lower toxicity chemicals can be stream-lined, i.e., a 

screening-level assessment procedure rather than multiple tiers of assessments with progressively 

more data requirements. 
Page 23 of 58

If stakeholders believe that submission of predicted data can fulfill one of the data needs for the 

Propylene Glycol, Dipropylene Glycol and Triethylene Glycol Case, then the Agency invites 

submission of this information. The submitter would be expected to supply a rationale describing 

the utility of the information and provide documentation on the scientific validity of the 

information. The determination that the predicted data fulfills the data requirement would be at 

the sole discretion of the Agency. Pre-submission consultation with the Agency is encouraged. 

6.1.5 Additional Information 

Stakeholders are also specifically asked to provide available information and data that will assist 

the Agency in refining its risk assessments, including any species-specific ecological effects 

determinations. The Agency is interested in receiving the following information: 

1. Confirmation on the following label information: 

A. Sites of application 

B. Formulations 

C. Application methods and equipment 

D. Maximum application rates 

E. Frequency of application, application intervals and maximum number of 

applications 

F. Geographic limitations on use 

2. Use or potential use distribution 

3. Use history 

4. Usage/use information for non-agricultural uses (e.g., materials preservation) 

5. Typical application interval 

6. State or local use restrictions 

7. Ecological incidents (non-target plant damage and avian, fish, reptilian, amphibian and 

mammalian mortalities) not already reported to the Agency 

8. Monitoring data 

7 Next Steps

After the 60-day comment period closes in August 2013, the Agency will review and respond to 

any comments received in a timely manner, and then issue a Final Work Plan for the Propylene 

Glycol, Dipropylene Glycol and Triethylene Glycol case.
Page 24 of 58

8 References 

Agency for Toxic Substances and Disease Registry (ATSDR). 1997. Toxicological Profile for 

Propylene Glycol. U.S. Department of Health and Human Services, Public Health 

Service, Atlanta, GA. 176 pp. http://www.atsdr.cdc.gov/ToxProfiles/tp189.pdf

Amdur, M.O., J. Doull, et al. (1991). Casarett and Doull's Toxicology: The Basic Science of 

Poisons. pp 705. MRID 46892501

ATSDR. 2008. Addendum to the Toxicological Profile for Propylene Glycol. Division of 

Toxicology and Environmental Medicine, Atlanta, GA. 17 pp. 

http://www.atsdr.cdc.gov/toxprofiles/propylene_glycol_addendum.pdf

Bartsch, W., G. Sponer, et al. (1976). Acute Toxicity of Various Solvents in the Mouse and Rat. 

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Arzneimittelforsch 26:1581-1583.

Braun, H.A. and G.F. Cartland. (1936). The Toxicity of Propylene Glycol. J. Am. Pharm. 

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Budden, R., U.G. Kuehl, et al. (1979). Experiments on the Toxic, Sedative, and Muscle

Relaxant Potency of Various Drug Solvents in Mice. Methods Toxicol. 102:467-474.

Bridie, A.L., C.J.M. Wolff, and M. Winter. 1979. The Acute Toxicity of Some Petrochemicals 

to Goldfish. Water Res. 13(7):623-626. (ECOTOX reference #623).

Bossert, N.L., et al. (1992) Reproductive Toxicity of Triethylene Glycol and its Diacetate and

Dimethyl ether Derivatives in a Continuous Breeding Protocol in Swiss CD-1 mice. Fund.

Appl. Pharmacol. 18: 602-608.

Budavari, S., M.J. O’Neill, A. Smith, and P.E. Heckelman (eds.)1989. The Merck Index: An 

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Campbell and Beavers, 1995. Acute oral toxicity of dipropylene glycol to Northernbobwhite. 

Unpublished data. MRID 43760807. 

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Unpublished data. MRID 43762301.

Clark C.R., T.C. Marshall, et al. (1979). Toxicological Assessment of Heat Transfer Fluids 

Proposed for Use in Solar Energy Applications. Toxicology and Applied Pharmacology 

51:529-535.
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Clayton, G.D. and F.E. Clayton (eds.). Patty’s Industrial Hygiene and Toxicology: Volume

2A, 2B, 2C: Toxicology. 3rd ed. New York: John Wiley Sons, 1981-1982. 3839.

Collins, 1995. Acute toxicity of propylene glycol to the waterflea (Daphnia magna). Unpublished 

data. MRID 43888003.

Conquet, P., et al. (1977). Evaluation of Ocular Irritation in the Rabbit: Objective versus 

Subjective Assessment. Toxicology and Applied Pharmacology 39:129-139. MRID 

46892502

Cornell, J.S., D.A. Pillard, and M.T. Hernandez. 2000. Comparative Measures of the Toxicity of 

Component Chemicals in Aircraft Deicing Fluid. Environ. Toxicol. Chem. 19(6):1465-

1472. (ECOTOX reference #48385).

Davis, K. (1993) Compilation of Toxicology Data References for Triethylene Glycol: Lab Project

Number: TEGTOX. Unpublished study prepared by RegWest Co. 131 (MRID 

42814404)

Draize, J.H., et al. (1944). Journal of Pharmacology and Experimental Therapy 82:377.

Driscoll, C.D., M.F. Kubena, et al. (1993). Propylene Glycol: Developmental Toxicity Gavage 

Study III in CD-1 Mice. Danbury (CT): Industrial Chemicals Division, Union Carbide 

Chemicals and Plastics Company Inc.

Gaunt, I.F., F.M.B. Carpanini, et al.(1972). Long-Term Toxicity of Propylene Glycol in Rats. 

Food Cosmetics and Toxicology 10:151-162. MRID 46892504

Gimeno, S., Komen, H., Gerritsen, A.G., and Bowner, T. (1998a): Feminisation of young males 

of the common carp, Cyprinus carpio, exposed to 4-tert-pentyphenol during sexual 

differentiation. Aquatic Toxicology (Amsterdam) 43: 77-92.

Guillot, J.P., et al. (1982) Safety Evaluation of Some Humectants and Moisturizers Used in

Cosmetic Formulations. International J. Cosmetic Sci., 4: 67.

Goldstein, I., et al. (1970) Toxicity of Glycol Derivatives. Igenia.

Graves and Swigert, 1995. Acute toxicity of dipropylene glycol to the waterflea 

(Daphnia magna). MRID 43760808. 

Graves and Swigert, 1995. Acute toxicity of propylene glycol to the waterflea (Daphnia magna). 

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Page 26 of 58

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Page 34 of 58

Appendix A Toxicology Profile

Acute Toxicity for Product Labeling 

Dipropylene glycol 

The dipropylene glycol (DiPG) toxicological database is comprised of studies submitted by the 

Glycols Joint Venture Consortium and published literature studies. Low acute toxicities for 

DiPG were established in rodents, rabbits, and guinea pigs. Acute LD50 values appear to be 

relatively high concentrations and fall within the toxicity classification of category IV for all of 

the acute experiments (Table 1). Acute oral LD50 values were greater than 5010 mg/kg/day when 

DiPG was administered to Sprague-Dawley male and female rats (43760801). When DiPG was 

administered topically to NZW rabbits, the dermal LD50 was also greater than 5010 mg/kg/day

(highest dose tested). No toxicological effects were observed at the doses tested in the acute 

dermal toxicity study (43760802). 

In a 4-hour inhalation whole-body exposure study with Sprague-Dawley rats, the LC50 was found 

to be greater than 2.34 mg/L. There were no treatment-related effects observed in rats exposed 

to DiPG and all of the animals survived the exposure and observation period with no indication 

of toxicity (43760803).

Instillation of 0.1 mL DiPG in eyes of New Zealand White (NZW) rabbits showed no evidence 

of corneal damage and was classified as a slight irritant based on observed conjunctival irritation 

that subsided within 24 hours (43760804). DiPG (0.5 mL of 100% TGAI) was administered to 

NZW rabbits in a primary dermal irritation study. There was evidence of erythema in a single 

site that subsided in 24 hours while there were no traces of edema observed in treated animals; 

DiPG was classified as a non irritant (43760805). 

A study for dermal sensitization assessed a single challenge application of 0.5 mL DiPG (100% 

purity) to guinea pigs that had previously been treated with DiPG. The topical administration did 

not produce any evidence of dermal sensitization in treated animals (43760806). 

In multiple open literature reports, when rats were exposed to DiPG, the acute oral toxicity LD50

values were similar to PG values and ranged from greater than 5000 to 15000 mg/kg/day for 

treated animals (46892504). DiPG was found to be an irritant to rabbits when administered in 

an undiluted dose of 510 mg in a primary eye irritation study (NIOSH, 1981). 

Intraperitoneal and intravenous injections to rodents resulted in toxicity values similar to other 

acute studies, with LD50 values ranging from 4600-10000 and 5800-11500 mg/kg/day, 

respectively (Latven, 1939; Bartsch, 1976; Sax, 1979; Fischer, 1949; Weatherby, 1938; Budden, 

1979).
Page 35 of 58

Table 14 Acute Toxicity Profile of Dipropylene Glycol

Guideline Study Type MRID Number

and/or Citation

Results Toxicity 

Category

870.1100 Acute Oral - Rat 43760801 LD50 = > 5010 mg/kg IV

870.1100 Acute Oral - Rat 46892504; NIOSH, 1981 LD50 > 5000-15000 mg/kg IV

870.1200 Acute Dermal - Rabbit 43760802 LD50 = > 5010 mg/kg IV

870.1300 Acute Inhalation - Rat 43760803 LC50= > 2.34 mg/L IV

870.2400 Acute Eye Irritation -

Rabbit

43760804 Slight irritant IV

870.2400 Acute Eye Irritation -

Rabbit

NIOSH, 1981 Irritant IV

870.2500 Acute Skin Irritation -

Rabbit

43760805 Non irritant IV

870.2600 Skin Sensitization -

Guinea Pig

43760806 Non sensitizer N/A

N/A = Not applicable

Propylene glycol

The toxicological database for propylene glycol (PG) is comprised of published literature studies

(Table 1). Acute oral toxicity studies yielded similar, low acute toxicities with relatively high 

LD50 values (all considered to be Toxicity Category IV) ranging from 8000-46000 mg/kg/day 

PG for rodents and 18000-20000 mg/kg/day for both rabbits and guinea pigs. Signs of nervous 

system toxicity were reported in the rabbit and guinea pig at lethal doses whereas effects of this 

nature (loss of balance, marked depression, and analgesia) were only evident in one study with 

mice at LD50 values of 23000-24900 mg/kg/day (46892501; 46892509; Clark, 1979; Bartsch, 

1976; Sax, 1979; Layton, 1987). 

PG induced degeneration of goblet cells (+69%) in the tracheal lining of rabbits after 20 and 120 

minutes of aerosol exposure in an acute inhalation toxicity study; no other toxicological effects 

were observed (Konradova, 1978). In primary eye irritation studies, PG was instilled in the eyes 
Page 36 of 58

of rabbits (0.1-0.5 mL). There were no treatment-related effects on the corneas of the animals 

and PG was classified as a non-irritant (46892104; 46892502; 46892507; Clark, 1979; Draize, 

1944; Guillot, 1982). Acute dermal toxicity studies were not available for PG. In a series of 

skin sensitization tests, no reactions were observed in guinea pigs exposed to solutions of PG up 

to 70% active ingredient (46892104).

Additionally, several studies established intraperitoneal and intravenous LD50 values for mice, 

rats, and rabbits. The acute LD50 values for intraperitoneal injection of PG ranged from 11200-

13000 mg/kg/day for rodents. Similar, but lower, values were observed in intravenous injections 

experiments; with LD50 ranges of 6200-8000 mg/kg/day for rodents and 6500 mg/kg/day for 

rabbits (Latven, 1939; Bartsch, 1976; Sax, 1979; Fischer, 1949; Weatherby, 1938; Budden, 

1979). 

Table 15 Acute Toxicity Profile of Propylene Glycol

Guideline Study Type MRID Number

and/or Citation

Results Toxicity 

Category

870.1100 Acute Oral - Rat 46892501; 46892509;

Clark, 1979; Bartsch, 

1976; Sax, 1979; 

Layton, 1987

LD50 = 8000-46000 mg/kg IV

870.1300 Acute Inhalation - Rat Konradova, 1978 LC50 > 2.0 mg/L (no deaths) IV

870.2400 Acute Eye Irritation -

Rabbit

46892104; 46892502;

46892508; Clark, 1979; 

Draize, 1954; 

Guillot, 1982

Non irritant IV

870.2500 Acute Skin Irritation -

Rabbit

Clark, 1979 Non irritant IV

870.2600 Skin Sensitization –

Guinea pig

Kero, 1980 Non sensitizer NA

N/A = Not applicable

Triethylene Glycol

Published literature studies submitted by the Glycols Joint Venture consortium show low 

toxicity (Toxicity Categories III and IV) following acute exposures (Table 16). The acute oral

and dermal toxicity of the chemical appears to be low, with reported oral LD50 values ranging

from 15-22 g/kg compiled from monographs and review articles. The data available on acute
Page 37 of 58

dermaltoxicity were not sufficient to establish a dermal LD50, but the data requirement was 

waived based on the low order of toxicity observed in other studies with triethylene glycol. 

Data on inhalation toxicity showed a maximum tolerated level of 800 mg/m3 in rats, but

intratracheal instillation of 0.25 cc undiluted chemical caused marked pulmonary irritation,

edema, and later, fibrosis and abcess formation in these animals (intratracheal instillation is not

an accepted route of administration for the Agency’s toxicity testing guidelines). Published

literature data on the skin and eye irritation as well as skin sensitization showed triethylene

glycol to be non-irritating to the skin and eye (when tested at the limit doses established by the

Agency for acute toxicity testing) and not a dermal sensitizer (Safety Assessment of 

Triethylene Glycol and PEG-4, 2003; Budavari, 1989; Clayton, 1981-1982; Smyth, 1941).

Triethylene glycol was evaluated for acute inhalation toxicity in male and female SpragueDawley albino rats in a study submitted to the Agency’s Office of Toxic Substances. A review

of this study by the Agency established a four hour LC50 greater than 5.2 mg/L and places acute

inhalation in Toxicity Category IV. Based on these results, this study is considered adequate for

regulatory purposes and it now replaces the earlier submitted acute inhalation information 

(Nachreiner, 1991).

Table 16 Acute Toxicity Profile of Triethylene Glycol

Guideline Study Type MRID Number

and/or Citation

Results Toxicity 

Category

870.1100 Acute Oral - Rat 42814404 LD50 = 15-22 g/kg

IV

870.1200 Acute Dermal - Rabbit 42814404 LD50 not determined

Study

Requirement 

Waived

870.1300 Acute Inhalation - Rat Nachreiner, 1991 LC50 > 5.2 mg/L

IV

870.2400 Acute Eye Irritation -

Rat 42814404 Mild irritant

III

870.2500 Acute Skin Irritation -

Rabbit

42814404 Slight irritant IV

870.2600 Skin Sensitization 42814404 Son- sensitizer

N/A
Page 38 of 58

Subchronic Toxicity Subchronic Toxicity

Propylene glycol

Subchronic toxicity studies for PG were available from published open literature studies. With 

relatively high-dose and no-observed-adverse-effect levels (NOAEL), PG exhibits low toxicity 

to animals exposed over a moderate period of time. In a 15-week feeding study, there were no 

adverse toxicological effects observed in rats administered 2500 mg/kg/day PG (46892504). In 

another subchronic toxicity study, PG was administered to rats in drinking water for 140 days. 

Although there were clinical signs (CNS depression and minor liver toxicity) exhibited in 

animals at a dose of 13200 mg/kg/day, these effects occurred well above the testing limit dose of 

1000 mg/kg/day established for an oral subchronic toxicity study in rats (Seindenfeld, 1932).

In a 90-day inhalation study, female rats were exposed to PG vapors (1.0 or 2.2 mg/L) for 6 

hours/day, 5 days/week over a period of 90 days. Animals experienced decreases in body weight 

and food consumption, although there were no changes in respiratory rates, minute volumes, or 

tidal volumes during exposure. With the exception of a significant increase in the number of 

goblet cells in the nasal passages of the mid- and high-dose animals (both male and female) 

males were unaffected by PG treatment (0.16, 1.0, or 2.2 mg/L) in this subchronic inhalation 

study (46892103).

Dipropylene glycol

Two published literature studies were available to address the subchronic toxicity of DiPG. In a

drinking water study, DiPG was administered to mice at concentrations of 715, 1350, 2620, 

4790, or 11000 mg/kg/day for males and 1230, 2140, 4020, 7430, or 14700 mg/kg/day for 

females over a period of 90 days. There were treatment-related increases in mortality at the highdose for both males and females and increased body weight in females treated with 2140 

mg/kg/day DiPG. Minimal toxicity was observed at these relatively high doses of DiPG; 11000 

and 14700 mg/kg/day for males and females, respectively (46892101).

In a similar study, male and female rats exhibited reductions in body weight at 425 and 1690 

mg/kg/day, respectively, when exposed to DiPG in drinking water for 90 days (425, 890, 1840, 

3890, or 12800 mg/kg/day for males and 460, 920, 1690, 3340, or 8950 mg/kg/day for females). 

Water consumption increased at the high-dose for all animals by the second week and continued 

throughout the remainder of the study. There were increases in weight and the appearance of 

lesions in liver and kidneys of treated animals at concentrations exceeding those that induced 

body weight reductions. High-dose (12800 mg/kg/day) males experienced testicular effects, 

hypoactivity and poor hair coats (46892208).

Triethethylene Glycol

Repeat oral dosing studies conducted in rats to determine triethylene glycol toxicity showed, in 

general, that the chemical was either without any adverse effects or produced toxicities only at 

doses at or greater than the limit doses established for EPA guideline test requirements. 

Triethylene glycol administered in the drinking water to rats at concentrations of 3% and 5% by 

volume for 30 days showed signs of toxicity (weight loss, alopecia and poor grooming) at the 
Page 39 of 58

lower concentration with one animal dying on day 25 of the study. All rats in the 3% test group 

survived to study completion with no signs of toxicities (Lauter, 1940).

 In a 14-day oral toxicity

study, Fischer 344 rats receiving triethylene glycol in the feed (doses equivalent to 1132, 2311, or

3916 mg/kg/day for males and 1177, 2411, or 6209 mg/kg/day for females) showed only changes 

in urinalysis (increased urine volume, decreased urine pH, and decreased urine triple phosphate 

crystals) at the highest respective doses tested in male and female rats (Union Carbide, 1989).

 In

a third oral toxicity study conducted for 90-days in rats, triethylene glycol was administered in the

diet at doses of 748, 1522 or 3849 mg/kg/day (males) and 848, 1699, or 4360 mg/kg (females). 

Although toxicities were noted at the high dose in male and female rats (decreases in body

weight, slight decreases in hemoglobin and hematocrit, slight increases in mean corpuscular

volume, and increased relative kidney and brain weights), these effects were noted at dose levels 

that exceed the established limit dose of 1000 mg/kg/day for such studies Union Carbide, 1990).

In a 21-day dermal toxicity study, there was no evidence of dermal or systemic toxicity from 

repeated dermal applications of 2ml (approximately 600 mg/kg) triethylene glycol applied to the 

skin of rabbits (Guillot, 1982). These results are supported by triethylene glycols’ low dermal

irritancy a negative response as a skin sensitizer (42814404).

Sprague-Dawley rats exposed (whole body) to triethylene glycol in an aerosol inhalation study at

concentrations of 494, 2011, or 4842 mg/m3 (0.5, 2.0, or 5.0 mg/L/day), for six hours a day, nine

times over a two-week period showed the following toxicities at the highest concentration level

tested: ataxia, prostration, unkept fur, labored respiration (males only), ocular discharge, swollen

periocular tissue, perinasal and perioral encrustation, blepharospasm and reduced body weight

Necropies revealed hyperinflation of the lungs, ocular opacity, congestion and hemorrhage in

many organs and tissues (pituitary gland, brain, nasal mucosa, kidney, thymus and lungs). All 

high-dose group rats died or were sacrificed moribund by day 5 of the study. Clinical signs of

toxicity observed at the low- and mid-dose of 0.5 and 2.0 mg/L/day, respectively, were limited to

swollen periocular tissues and perinasal encrustations. Treatment-related changes in organ

weights in mid-dose males included an increase in liver and kidney weights relative to body 

weight; mid-dose females showed increases in absolute and relative (to body and brain weights) 

liver and kidney weights. Statistically significant clinical chemistry findings for males treated with 

2.0 mg/L/day triethylene glycol included an increase in ALT activity and a decrease in serum 

creatinine levels. Mid-dose females showed increases in urea nitrogen, inorganic phosphorus, 

ALT and ALK activity, and decreases in glucose, creatinine, and chloride. However, the changes 

in organ weights and clinical chemistry findings were not correlated with any histopathological 

observations (Sun, 1992).

Rats exposed to the test material via a whole-body inhalation protocol are also receiving the 

chemical via the oral and dermal routes. These additional routes of exposure may have

increased the total dose received and contributed to the toxicities observed in the whole-body

exposure inhalation study. Therefore, a second study was conducted using a nose-only

exposure for 6 hours a day, 9 consecutive days. In this second inhalation toxicity study, mean

exposure concentrations of 102, 517, or 1036 mg/m3 (approximately 0.1, 0.5, 1.0 mg/L/day)

triethylene glycol produced no treatment-related toxicities at any dose tested (Norris, 1994).

Monkeys exposed by inhalation to approximately 1 ppm vapor from two weeks to 13 months 

and human volunteers exposed to air saturated with vapor (approximately 0.5 to 1 ppm)
Page 40 of 58

showed no adverse reactions or histopathological changes suggestive of toxicity from

prolonged exposure to triethylene glycol (Robertson, 1947).

Dogs given daily intravenous injections (0.1 or 0.5 ml/kg) of triethylene glycol for four weeks 

showed no mortality or toxicity with the exception of flattened epithelial cells in the urine and 

phlebitis at the site of injection (Stenger, 1968).

Developmental and Reproductive Toxicity

Open literature studies examining the developmental and reproductive toxicity of 

propylene/dipropylene/triethylene glycol showed minimal evidence of toxicity at relatively high 

concentrations (10000 mg/kg/day) that exceed the established limit dose of 1000 mg/kg/day. 

Propylene glycol

PG, administered to mice at a concentration of 10000 mg/kg/day in drinking water, did not 

produce any overt adverse effects in fetal development (46892201). In a second study, PG 

administered to mice via subcutaneous injections at a dose of 10400 mg/kg/day on gestation day 

(GD) 9, 10, and 11 did not exhibit significant increases in fetal malformations (46892203). Two

additional studies involving oral administration of PG in mice up to concentrations of 10400 

mg/kg/day did not induce any maternal, reproductive, or developmental toxicity in this study 

(46892508; Driscoll, 1993). 

Several developmental studies were performed on rats, mice, rabbits, and hamsters in which oral 

doses of PG, that ranged from 12.3-1600 mg/kg/day, were administered during gestation. In all 

four studies, there were no incidents of treatment-related maternal, reproductive, or 

developmental toxicities observed in this study (46892207; FDRL, 1973; NTP, 1973).

PG was administered to rats (1600-6200 mg/kg/day), mice (1550-10000 mg/kg/day), and rabbits 

(1230 mg/kg/day) during gestation via a stomach tube. There were no adverse reproductive 

effects observed in any of these experiments. However, a slight maternal toxicity was noted in 

mice treated with 10000 mg/kg/day PG (highest dose administered) on GD 8-12 (46892508; 

FDRL, 1973). 

In a second reproductive toxicity study, rats from three successive generations were orally 

administered 2.5, 5, 7.5, 10, 20, or 30% PG. No adverse effects were observed up to the 20% 

dose (equivalent to a dietary level of approximately 11900 mg/kg/day), where 50% of the 

animals failed to produce offspring. No offspring were produced by any of the rats in the 30% 

high-dose PG group (Guerrant, 1947). 

Mice were administered 1820, 4800, or 10100 mg/kg/day in drinking water over a course of 18 

weeks in a third reproductive toxicity study. There were no treatment-related maternal, 

reproductive, or offspring effects observed at any of the PG doses tested in this study 

(46892204).

Dipropylene glycol
Page 41 of 58

DiPG was administered to NZW rabbits in a developmental toxicity study at concentrations up to 

1200 mg/kg/day on GD 6-19. No treatment-related maternal, reproductive, or developmental 

toxicities were observed in treated animals (46892205). However, there were decreases in 

maternal food consumption and body weight in rats treated with 2000 and 5000 mg/kg/day 

DiPG. Increases in liver weight were also observed in these dose groups. No reproductive or 

developmental toxicity effects were observed in rats at any dose levels of DiPG from 800-5000 

mg/kg/day (46892206).

Triethylene glycol

Triethylene glycol was administered orally at doses of 0, 0.5, 5.6, and 11.27 g/kg/day in 

timed pregnant CD-1 mice from gestation Days 6 through 15. There were no treatment

related maternal deaths and no abortions. Hyperactivity and rapid respiration were observed

at the highest dose level tested. No effects were observed on maternal weight gain or food

consumption at any dose level. Pregnancy outcome was unaffected at any dose level tested. 

There were no treatment-related effects observed for external or visceral malformations in

offspring. Some evidence of delayed ossification was observed at the high dose level (Union 

Carbide, 1990).

In a second study, pregnant Sprague-Dawley rats were administered triethylene glycol by 

gavage on gestation days 6 through 15 at dose levels of 0, 1.0, 5.6, and 11.27 g/kg/day. There 

were no effects on maternal mortality and there were no abortions. Clinical toxicity was

observed in maternal rats at the high dose and consisted of audible respiration, periocular

encrustation, and perioral wetness. Decreased body weight and food consumption was observed

in maternal rats at the 5.6 g/kg/day dose. No effects were observed at the 1.0 g/kg/day dose. In

offspring, mean fetal body weight was decreased at the 11.27 g/kg/day dose level, but there

were no treatment- related increases in external, visceral, or skeletal malformations Union 

Carbide, 1991). Published literature examined the effect of triethylene glycol on reproduction in

Swiss CD-1 mice. Doses of 0, 0.3, 1.5, and 3% were administered in drinking water using a

continuous breeding protocol. No effects on reproductive function were observed at any dose

level tested (up to the high dose of 6.78 g/kg) including sperm concentration, morphology, and

motility. Reduced pup weight was observed at the 1.5 and 3% doses of triethylene glycol

(Bossert, 1992; Lamb, 1997).

In a study submitted to the Agency, rats were exposed to an atmosphere saturated with 

triethylene glycol (approx. 1 ppm) for 12-18 months with no adverse reproductive effects 

noted (Robertson, 1947; Goldstein, 1970).

The available developmental and reproductive studies conducted with triethylene glycol are 

from published sources or from studies submitted to the Office of Toxic Substances and do

not report all the data that are normally reported under the OPPTS 870 toxicity test

guidelines. However, it is apparent that the toxicities observed in these studies are

consistently manifested only at doses of triethylene glycol that exceed the established limit

doses for animal studies and are of a non-specific nature. Therefore, there is no concern for

the developmental or reproductive toxicity of triethylene glycol.
Page 42 of 58

Chronic Toxicity and Carcinogenicity

Published literature studies examining the chronic toxicity and carcinogenic potential of 

propylene/dipropylene/triethylene glycol have shown the chemicals to be noncarcinogenic in 

rodent and non-rodent species under the conditions of each study protocol. In addition, systemic 

adverse effects were noted only at doses of propylene, dipropylene, and triethylene glycol that 

exceed the limit dose of 1000 mg/kg/day established for mammalian chronic toxicity studies.

Propylene glycol

Several studies in the rat involving dietary, drinking water, and inhalation exposure to PG 

comprise the chronic toxicity database. There was little evidence of adverse toxicological effects 

at the relatively high concentrations used within these studies and chronic toxicity associated 

with PG was low. With the exception of slight liver damage in treated animals, there were no 

signs of toxic effects when PG was administered 1230 or 2450 mg/kg/day in the diet for 2 year 

(Morris, 1942). In another study, slight liver damage and no other effects were observed in a 2-

year drinking water study that administered 1834 mg/kg/day PG to rats (46892509; Braun, 

1936).

In a continuous-exposure inhalation study, rats were exposed to 0.17-0.35 mg/L PG for 18 

months and a chronic toxicity lowest observed adverse effect level (LOAEL) of 0.35 mg/L was 

established based on a 50% increase in body weight. There were no other effects observed in 

treated animals in this study (Robertson, 1947).

A carcinogenicity study in rats fed PG at dietary concentrations of 200, 400, 900, or 1700 

mg/kg/day for males and 300, 500, 1000, or 2100 mg/kg/day for females was carried out for 2 

years with little evidence of chronic toxicity or significant treatment-related neoplasms 

(46892504). In a dermal carcinogenicity study conducted in mice, there was no change in 

longevity or increase in dermal tumors following chronic treatment with 0.02 mL of 10, 50 or 

100% (46892301).

Dipropylene glycol

There were decreases in survival and body weight of male and female rats treated with 3040 and 

2330 mg/kg/day DiPG, respectively, in drinking water for 2 years. Clinical signs of toxicity 

were noted in males with an increase in focal histiocytic and focal granulomatous inflammation 

in the liver. There was no evidence of carcinogenic activity in rats treated with DiPG over the 

course of 24 months (NTP, 2003e). In a similar mouse study, animals experienced decreased 

survival and body weight at the high-dose (2390 mg/kg/day for males and 1950 mg/kg/day for 

females) of DiPG tested in the study. Males in the 2390 mg/kg/day dose group also exhibited 

reduced water consumption. After 2 years of DiPG administration in drinking water, mice failed 

to show any evidence of carcinogenic activity (NTP, 2003d).

Triethylene glycol

Published literature sources examining the chronic toxicity and carcinogenic potential of 

triethylene glycol have shown the chemical to be non toxic/negative in rodent species.
Page 43 of 58

In a 12 month study, monkeys receiving triethylene glycol (0.25 mL to 0.5 mL) orally in egg 

nog (approximately 50 to 100 times the quantity an animal could absorb by breathing glycol 

saturated air) showed no adverse effects in physiological function or organ histopathology 

(Robertson, 1947).

Triethylene glycol administered in feed at levels of 0, 1, 2 or 4% to Osborn-Mendel rats for 2 

years showed that the body weight gains, hematological parameters and clinical chemistries

were not affected by treatment. Under the conditions of this study, triethylene glycol was not 

carcinogenic in rats. The doses tested in rats are equivalent to as much as 3 to 4 g/kg/day, 

which are well above the upper limit dose of 1 g/kg/day (1000 mg/kg/day) for testing pesticides 

via the oral route in subchronic and chronic toxicity studies (Fitzhugh, 1946).

Mutagenicity 

Open published literature studies comprise the mutagenicity database for propylene/dipropylene 

glycol/triethylene glycol. In a battery of studies, propylene and dipropylene glycol did not 

exhibit mutagenic or genotoxic activity. 

Propylene glycol

There were no signs of mutagenicity in several bacterial reverse mutation tests in tester strains 

TA 1535, TA 1537, TA 100, TA 98, and TA 1538 that were performed with concentrations of 

PG ranging from 1-10000 μg/plate. PG did not induce mutant colonies and was negative in all 

cases (46892102; 46892503; Clark, 1979). Similar negative results were observed in additional 

mutagenicity studies, including an in vitro mammalian cell gene mutation test, an in vitro

mammalian chromosome aberration test, a mammalian erythrocyte micronucleus test, and a 

dominant lethal assay (46892506; Litton Bionetics, 1974; Swenberg, 1976).

Dipropylene glycol

Non-mutagenic results were observed in both a bacterial reverse mutation and in vitro

mammalian cell gene mutation test. There was no increase in mutant frequencies when DiPG 

was administered (100-10000 μg/plate) to the bacterial tester strains TA 98, TA 100, TA 1535, 

and TA 1537 (NCI, 1986). In an in vitro mammalian cell gene mutation test, mice were given 

0.005, 0.01, 0.05, 0.1, 0.5, 1.0, 5.0, 10, or 50 μL/mL DiPG and failed to produce a positive 

response in either the presence or absence of metabolic activation (NCI, 1987). 

Triethylene glycol

Triethylene glycol was tested for mutagenic or genotoxic potential and found to be negative in a

battery of studies: a bacterial gene mutation assay using Salmonela typhimurium, an in vitro 

Chinese hamster ovary (CHO) mutation assay, an in vitro Chinese hamster ovary (CHO) 

chromosomal aberration assay and an in vitro sister chromatid exchange assay (Guzzie, 1986a; 

Guzzie, 1986b; Slensinski, 1986a; Slensinski, 1986b).

Neurotoxicity
Page 44 of 58

From the available toxicity studies, evidence of neurotoxicity was observed in mice, rabbits, and 

guinea pigs following a single dose of propylene glycol; loss of balance, marked depression, and 

analgesia observed at lethal doses of 18400-24900 mg/kg/day (Braun, 1936; Laug, 1939; Smyth, 

1941; Latven, 1939). Central nervous system (CNS) depression was also noted in rats 

administered propylene glycol at greater than 13200 mg/kg/day in drinking water for 140 days 

(Seidenfeld, 1932). However, these CNS effects were observed only at a dose level that far 

exceeds the established limit dose (1000 mg/kg/day) for an oral subchronic toxicity study. Based 

on a weight-of-evidence evaluation of the available data, the Agency does not anticipate needing 

neurotoxicity testing, including a developmental neurotoxicity study for either propylene or 

dipropylene glycol. 

Metabolism and Excretion

Propylene glycol

In an elimination and metabolism study a maximum concentration of 29.21∀2.92 mmol/L PG 

was found in the blood of rats 2 hours with the high-dose administration of PG (treatment with 

4.83, 9.66, 19.32, 38.64, and 77.28 mmol/kg PG) (Morshed, 1988). PG was readily absorbed in 

the gastrointestinal tract of several animals in other studies. The absorption was rapid and 

complete and PG was broken down into glycogen (Hanzlik, 1939; Opitz, 1958; Salter, 1935; Van 

Winkle, 1941). PG was administered orally to humans (70 g) and dogs (150 g) in a NTIS study 

in which a portion of PG was metabolized and an appreciable fraction was excreted in the urine. 

Within 10 hours, 20-25% of the 70 g dose given to the human subjects was excreted. The dogs 

excreted 20% of the 150 g dose within 24 hours (Hanzlik, 1939). 

Dipropylene glycol

No metabolism studies conducted with DiPG are available in the toxicity data base.

Triethylene glycol

The fate of 14C-labeled triethylene glycol in rats and of unlabeled material in rabbits was recently

studied. Following oral dosing, the rat and rabbit excreted most of the triethylene glycol in both

unchanged and/or oxidized forms (mono- and dicarboxylic acid derivatives of triethylene glycol). 

In rabbits dosed with 200 or 2000 mg/kg triethylene glycol respectively excreted 34.3% or 28%,

of the administered dose in the urine as unchanged triethylene glycol and 35.2% as a hydroxyacid

form of this chemical. In the studies with rats, little if any C14-oxalate or C14- triethylene glycol in

conjugated form was found in the urine. Trace amounts of orally administered 14C triethylene

glycol were excreted in expired air as carbon dioxide (<1%) and in detectable amounts in feces (2

to 5 %). The total elimination of radioactivity (urine, feces and CO2) during the five day period

following an oral dose of labeled compound (22.5 mg) ranged from 91 to 98%. The majority of

the radioactivity appeared in the urine (McKennis, 1962).
Page 45 of 58

Dermal Absorption

Propylene glycol

There have been no reports dealing with PG and skin absorption. PG has been found to penetrate 

the outermost layer of the epidermis; however, because of this property, PG is commonly used as 

a cosmetic ingredient in many products. Although absorption through the skin is possible, it is 

doubtful any appreciable systemic/dermal injury would occur based on the lack of irritation in 

acute dermal studies, no evidence of chronic toxicity or tumor response following a 2-year 

dermal application study, and the widespread use in cosmetics that is considered safe 

(46892301; Clark, 1979). 

Dipropylene glycol

No dermal penetration/skin absorption studies were identified for dipropylene glycol. Similar to 

PG, DiPG is used in many cosmetic formulations and has been generally recognized as a low 

toxicity chemical by the FDA. Dermal and systemic injury from skin exposure to DiPG is 

unlikely considering its widespread use in cosmetics, the lack of evidence of dermal toxicity in 

acute studies, and the lack of evidence of skin sensitization in repeat-exposure studies 

(43760802; 43760805; 43760806).

Triethylene glycol

No studies have been reported dealing with the skin absorption of triethylene glycol.

Although it is possible that, under conditions of very severe prolonged exposures to this chemical, 

absorption through the skin may occur, it is doubtful any appreciable systemic/dermal injury would

occur because triethylene glycol has 1) a low order of dermal irritancy (42814404), (2) is not a skin

sensitizer (42814404) and (3) showed no evidence of dermal or systemic toxicity following

repeated dermal applications of 2ml (approximately 600 mg/kg) triethylene glycol applied to the

skin of rabbits in a 21-day dermal toxicity study (Guillot, 1982).
Page 46 of 58

Appendix B Product Chemistry

Triethylene glycol, Propylene glycol and Dipropylene glycol product chemistry information is 

summarized in Table B1 (source: MRIDs 42814401, 42814402, 42814403, 43178601, 

43178603, 43179501, 43179502, 43179503, and EPI Suite v4.1).

Table 17– Product Chemistry of Triethylene, Propylene and Dipropylene Glycols

Guideline 

No. 

Physical and Chemical 

Properties Triethylene Glycol Propylene Glycol Dipropylene Glycol

830.1550 Product identity and 

composition 

Refer to Table 5 Refer to Table 5 Refer to Table 5

830.1600 Description of materials 

used to produce the 

product

Confidential Business 

Information (CBI)

CBI CBI

830.1620 Description of 

production process

CBI CBI CBI

830.1650 Description of 

Formulation Process

CBI CBI CBI

830.1670 Discussion of 

formulation of impurities

CBI CBI CBI

830.1700 Preliminary analysis CBI CBI CBI

830.1750 Certified limits CBI CBI CBI

830.1800 Enforcement analytical 

method 

Gas Chromatography (GC) GC GC

830.1900 Submittal of samples CBI CBI CBI

830.6302 Color Colorless viscous liquid Colorless viscous liquid Colorless viscous liquid

830.6303 Physical State Liquid Liquid Liquid

830.6304 Odor Mild, characteristic odor. Slight acrid to none. Practically odorless.

830.6313 Stability to normal and 

elevated temperature, 

metals/metal ions 

Stable at normal 

temperatures of use and 

storage. Exposure to 

elevated temperatures can 

cause decomposition.

Stable at normal 

temperatures of use and 

storage. Exposure to 

elevated temperatures 

can cause decomposition.

Stable at normal 

temperatures of use and 

storage. Exposure to 

elevated temperatures 

can cause decomposition.

830.6314 Oxidation/Reduction:

Chemical 

Incompatibility:

Not applicable. Product 

contains no oxidizing or 

reducing agents.

Incompatible with strong 

acids, strong bases, and 

strong oxidizers.

Not applicable. Product 

contains no oxidizing or 

reducing agents.

Incompatible with strong 

acids, strong bases, and 

strong oxidizers.

Not applicable. Product 

contains no oxidizing or 

reducing agents.

Incompatible with strong 

acids, strong bases, and 

strong oxidizers.

830.6315 Flammability Flash point: 177°C (Closed 

Cup).

Flash point: 191°C (Open 

Cup).

Flash point: 103 o C Flash point: 124 o C

830.6316 Explodability Not applicable. Product is 

not explosive.

Not applicable. Product 

is not explosive.

Not applicable. Product 

is not explosive.

830.7000 pH 6.0 - 9.5 Neutral Neutral

830.7050 UV/Visible Absorption Does not absorb light at Does not absorb light at Does not absorb light at 
Page 47 of 58

Guideline 

No. 

Physical and Chemical 

Properties Triethylene Glycol Propylene Glycol Dipropylene Glycol

wavelengths >290 nm and 

therefore it is not expected 

to be susceptible to direct 

photolysis by sunlight.

wavelengths >290 nm 

and therefore it is not 

expected to be 

susceptible to direct 

photolysis by sunlight.

wavelengths >290 nm 

and therefore it is not 

expected to be 

susceptible to direct

photolysis by sunlight.

830.7200 Melting point:

Freezing point:

Not applicable. Product is 

liquid at room 

temperature.

−4.3°C to −7 °C

Not applicable. Product 

is liquid at room 

temperature.

−59°C

Not applicable. Product 

is liquid at room 

temperature.

−59°C

830.7220 Boiling point 288.0°C at 760 mm Hg. 188 °C at 760 mm Hg 230 oC at 760 mm Hg

830.7300 Density 1.1255 g/mL at 25°C 1.032 g/ mL at 25°C 1.022 g/ mL at 25oC

830.7370 Dissociation Constant 

(pKa)

Not applicable. Does not 

dissociate in water.

Not applicable. Does not 

dissociate in water.

Not applicable. Does not 

dissociate in water.

830.7520 Particle size, fiber 

length, & diameter 

distribution 

Not Applicable; soluble in 

water

Not Applicable; soluble 

in water

Not Applicable; soluble 

in water

830.7550 Partition coefficient

(Log Kow)

−1.75 − 0.92 − 0.67

830.7840 Solubility in water Completely soluble. Completely soluble. Completely soluble.

830.7860 Solubility in organic 

solvents 

Soluble in alcohol, 

benzene, toluene, 

sparingly soluble in ether 

and insoluble in petroleum 

ether.

Soluble in ethanol, 

acetone, and most 

organic solvents.

Soluble in ethanol, 

acetone, and most 

organic solvents.

830.7950 Vapor pressure 0.00132 mm Hg at 25°C 0.13 mm Hg at 25°C 0.016 mm Hg at 25°C
Page 48 of 58

Appendix C Ecotoxicology Profile for 

Propylene Glycol and Dipropylene Glycol

Toxicity to Terrestrial Animals

Avian acute oral and dietary toxicity

To establish the toxicity of propylene glycol and dipropylene glycol to birds, the Agency 

required an acute oral toxicity study using the technical grade of the active ingredient (TGAI). 

The preferred test species was either mallard duck (a waterfowl) or bobwhite quail (an upland 

game bird). The results of submitted studies are provided in the following table (Table 18). The 

results indicate that both propylene and dipropylene glycol are practically non-toxic to birds on 

an acute oral basis. The studies are acceptable and fulfill guideline requirements (71-1/OPPTS 

850.2100).

A subacute dietary study using the TGAI was not required for propylene glycol or dipropylene 

glycol because of a lack of acute toxicity in the bobwhite quail (Table 16). 

Table 18 Acute Oral Toxicity of Propylene and Dipropylene Glycol to Birds

Species % Active 

Ingredient (ai)

Endpoint

(mg/kg)

Toxicity 

Category 

(TGAI)

Satisfies 

Guidelines/

Comments

Reference

Propylene Glycol

Northern bobwhite

(Colinus 

virginianus)

100 LD50 > 2000

NOEL = 2000

Practically nontoxicYes Campbell and 

Beavers, 1995

MRID 43762301

Northern bobwhite

(Colinus 

virginianus)

99.88 LD50 > 2150

NOEL = 2150

Practically nontoxicYes Pedersen, 1995

MRID 43888002

Dipropylene Glycol

Northern bobwhite

(Colinus 

virginianus)

100 LD50 > 2000

NOEL = 2000

Practically nontoxicYes

• core study

• 14-day test 

duration

Campbell and 

Beavers, 1995

MRID 43760807

Mammals

Both propylene and dipropylene glycol show low acute toxicity to mammals in laboratory 

studies, and do not produce developmental or reproductive effects at fairly high doses (Table 12, 

Appendix A).
Page 49 of 58

Table 19 Toxicity of Propylene and Dipropylene Glycol to Mammals (excerpted from 

Appendix A)

Species Test Type Results

Propylene Glycol

Rat Acute oral LD50 8000 - 46000 mg/kg (Toxicity Category IV)

Rat 15-week Subchronic

(feeding)

NOAEL = 2500 mg/kg/day

Mouse Developmental maternal, reproductive, developmental NOAEL = 10400 mg/kg/day (oral)

Dipropylene Glycol

Rat Acute oral LD50 >5010 mg/kg (Toxicity category IV)

Mouse 90-day Subchronic 

(drinking water)

NOAEL = 4790mg/kg/day male, 7430 mg/kg/day female

Rat Developmental reproductive, developmental NOAEL = 5000 mg/kg/day 

Toxicity to Aquatic Animals

Freshwater Fish, Acute

In order to establish the acute toxicity of an antimicrobial pesticide to freshwater fish for the 

listed propylene and dipropylene glycol use patterns, the Agency required a freshwater fish 

toxicity study using the TGAI. Data are generally required on only one species for these use 

patterns unless the active ingredient or principal transformation products are stable in the 

environment and the LC50 in the first species is less than or equal to 1 ppm. The preferred test 

species was rainbow trout (a coldwater fish) or bluegill sunfish (a warmwater fish). No fish 

acute toxicity testing has been submitted to the Agency. A survey of the EPA/ORD database 

ECOTOX provided multiple freshwater fish acute toxicity endpoints for propylene glycol, which 

are summarized in Table 20.

The results indicate that propylene glycol, dipropylene glycol and triethylene glycol are

practically non-toxic to freshwater fish on an acute basis. Since these data are supplemental 

information, Guideline 72-1/850.1075 is not fulfilled; however, because multiple published 

studies demonstrate very low toxicity to freshwater fish, no further testing is required for 

propylene glycol, dipropylene glycol, triethylene glycol.

Table 20 Acute Toxicity of Propylene and Dipropylene Glycol to Freshwater Fish

Species Endpoints Toxicity Category Reference

Propylene Glycol

Goldfish (Carassius 

auratus) Static 24 hr. LC50 >5000 ppm ai Practically non-toxic Bridie et al., 1979 (ECOTOX reference #623)

Rainbow trout 

(Oncorhynchus mykiss) Static 24-hr LC50 = 50,000 ppm Practically non-toxic Majewski et al., 1978 (ECOTOX reference # 991)

Fathead minnow 

(Pimephales promelas) 48 hr LC50 = 790 ppm Practically non-toxic Pillard, 1995(ECOTOX reference #13727)

Fathead minnow 

(Pimephales promelas) 96 hr LC50 = 710 ppm Practically non-toxic Pillard, 1995(ECOTOX reference #13727)
Page 50 of 58

Species Endpoints Toxicity Category Reference

Fathead minnow 

(Pimephales promelas) 96 hr LC50 = 62,000 ppm ai Practically non-toxic Pillard, 1995(ECOTOX reference #13727)

Dipropylene Glycol

Goldfish (Carassius 

auratus) 24 hr. LC50 >5000 ppm ai Practically non-toxic Bridie et al., 1979 (ECOTOX reference #623)

Freshwater Invertebrates, Acute

The Agency required a freshwater aquatic invertebrate toxicity study using the TGAI to establish 

the acute toxicity of an antimicrobial pesticide to freshwater invertebrates. The preferred test 

species is Daphnia magna.

The results of the studies in Table 19 indicate that propylene and dipropylene glycol are both 

practically non-toxic to freshwater invertebrates. The testing guideline requirement has been 

fulfilled (850.1010/72-2). Additional data on the acute toxicity of propylene glycol to freshwater 

invertebrates were retrieved from the ECOTOX database. This information is provided in Table 

22. Because the agency has acceptable, albeit limit7 study data, no formal agency review of the 

public literature studies were conducted. The results from the following studies do provide 

further weight –of-evidence that propylene and dipropylene glycol demonstrate very low toxicity 

to freshwater invertebrates. While not reviewed these results do provide further weight-ofevidence that propylene and dipropylene glycol demonstrate very low toxicity to freshwater 

invertebrates.

Table 21 Acute Toxicity of Propylene/Dipropylene Glycol to Freshwater Invertebrates

Species % Active 

Ingredient 

(ai)

Endpoints

(ppm)

Toxicity 

Category 

(TGAI)

Satisfies 

Guidelines/

Comments

Reference

Propylene Glycol

Waterflea 

(Daphnia 

magna)

100 48-hr. EC50 >110 ppm ai

NOEC > 110 ppm ai

Practically 

non-toxic Yes

Graves and 

Swigert, 1995. 

MRID 43762302

Waterflea

(Daphnia 

magna)

99.76 48-hr. EC50 >1,000 ppm ai

NOEC > 1,000 ppm ai

Practically 

non-toxic Yes Collins, 1995

MRID 43888003

Dipropylene Glycol

Waterflea

(Daphnia 

magna)

100 48-hr. EC50 > 109 ppm ai

NOEC > 109 ppm ai

Practically 

non-toxic Yes

Graves and 

Swigert, 1995. 

MRID 43760808

 7 A limit study or Tier I study refers here to a study where instead of testing several concentrations to establish a 

dose response and a definitive endpoint value, only a single concentration of at least 100 mg/L (ppm) or the 

solubility limit, whichever is lower, is tested.
Page 51 of 58

Table 22 Open Literature Freshwater Invertebrate Acute Toxicity Data for Propylene 

Glycol

Species Endpoints Toxicity Category Reference

Waterflea (Ceriodaphnia 

dubia)

48 hr. LC50 = 1,020 ppm ; 

NOEC = 660 ppm Practically non-toxic Pillard, 1995(ECOTOX reference #13727)

Waterflea (Ceriodaphnia 

dubia)

48 hr LC50= 18,340 ppm ai; 

NOEC = 13,020 ppm ai Practically non-toxic Pillard, 1995(ECOTOX reference #13727)

Waterflea (Ceriodaphnia 

dubia) 48 hr LC50 = 4,919 ppm ai Practically non-toxic Cornell et al., 2000(ECOTOX reference #48385)

Waterflea (Daphnia 

magna) 48 hr EC50 > 10,000 ppm Practically non-toxic Kuhn et al., 1989(ECOTOX reference #846)

Estuarine and Marine Organisms, Acute Toxicity

Acute toxicity testing with estuarine and marine organisms using the TGAI is required when the 

end-use product is intended for direct application to the marine/estuarine environment or effluent 

containing the active ingredient is expected to reach this environment. Neither propylene glycol 

nor dipropylene glycol has such uses on their labels and neither is exposure expected to occur. 

Therefore, testing with marine/estuarine organisms is not anticipated to be required. Some 

information on the acute toxicity of propylene glycol to an inland saltwater lake invertebrate 

species, brine shrimp,was found in ECOTOX, and the results are provided in Table 23. 

Estimates of propylene gylcol and dipropylene gylcol (neutral organics class) acute toxicity 

using ECOSAR v1.10 are 24,391 mg/L and 32,012 mg/L, respectively, for a saltwater fish and 

119,000 mg/L and 142,000 mg/L, respectively, for a mysid. 

Table 23 Acute Toxicity of Propylene Glycol to Inland Saltwater Lake Species

Species Endpoints Toxicity Category Reference

Brine Shrimp 

(Artemia salina) Static 24 hr. LC50 > 10000 ppm Practically nontoxic

Price et al., 1974

(ECOTOX reference #2408)

Aquatic Animals, Chronic Toxicity

There are no submitted chronic data in the files and no comparable endpoints were found in the 

open literature ECOTOX database. Estimates of propylene gylcol and dipropylene gylcol 

(neutral organics class) chronic toxicity to aquatic animals using ECOSAR v1.10 range from 413 

to 1,894 mg/L for freshwater animals and 484 to 26,858 mg/L for saltwater animals (Table 24). 

Chronic toxicity testing (Fish early life stage, 850.1300/72-4a and aquatic invertebrate life cycle, 

850.1400/72-4b) is not required for the currently registered uses of propylene glycol or 

dipropylene glycol. Therefore, aquatic animal chronic testing is not anticipated to be required at 

this time.
Page 52 of 58

Table 24 Chronic Toxicity of Propylene Glycol and Dipropylene Glycol to Aquatic 

Animals

Species Propylene Glycol Chv Dipropylene Glycol Chv Reference

Fish, Freshwater 1,422 mg/L 1,894 mg/L ECOSAR v1.10

Daphnid, Freshwater Invertebrate 413 mg/L 569 mg/L ECOSAR v1.10

Fish, Saltwater 484 mg/L 693 mg/L ECOSAR v1.10

Mysid, Estuarine/Marine Invertebrate 23,526 mg/L 26,858 mg/L ECOSAR v1.10

Chv = geometric mean of a NOEC and LOEC value

Toxicity to Plants

No data, such as phytotoxicity, were available from submitted studies or open literature to 

address the risk to plants. Estimates for toxicity to green algae for propylene gylcol and 

dipropylene gylcol, as neutral organics, from ECOSAR v1.10 consist of 96-h IC50 values of 

5,611 mg/L and 7,567 mg/L, respectively, and Chv (geometric mean of a NOEC and LOEC) 

values of 329 mg/L and 476 mg/L, respectively. This information is sufficient for any hazard 

labeling. Additionally, exposure to plants is not expected from the current registered uses of 

propylene glycol and dipropylene glycol. Therefore, plant toxicity testing is not anticipated to be 

required at this time. 

ECOSAR Version 1.10 Results Page—Propylene Glygol

SMILES : OCC(O)C

CHEM : 1,2-Propanediol

CAS Num: 000057-55-6

ChemID1: 

MOL FOR: C3 H8 O2 

MOL WT : 76.10

Log Kow: -0.782 (EPISuite Kowwin v1.68 Estimate)

Log Kow: (User Entered)

Log Kow: -0.92 (PhysProp DB exp value - for comparison only)

Melt Pt: (User Entered for Wat Sol estimate)

Melt Pt: -60.00 (deg C, PhysProp DB exp value for Wat Sol est)

Wat Sol: 1E+006 (mg/L, EPISuite WSKowwin v1.43 Estimate)

Wat Sol: (User Entered)

Wat Sol: 1E+006 (mg/L, PhysProp DB exp value)

--------------------------------------

Values used to Generate ECOSAR Profile

--------------------------------------

Log Kow: -0.782 (EPISuite Kowwin v1.68 Estimate)

Wat Sol: 1E+006 (mg/L, PhysProp DB exp value)

------------------------------------------------

Available Measured Data from ECOSAR Training Set

------------------------------------------------

 No Data Available

--------------------------------------
Page 53 of 58

ECOSAR v1.1 Class-specific Estimations

--------------------------------------

Neutral Organics

 Predicted

ECOSAR Class Organism Duration End Pt mg/L (ppm)

=========================== ================== ======== ====== ==========

Neutral Organics : Fish 96-hr LC50 19700.475

Neutral Organics : Fish 14-day LC50 18018.713

Neutral Organics : Daphnid 48-hr LC50 8688.484

Neutral Organics : Green Algae 96-hr EC50 5611.575

Neutral Organics : Fish ChV 1422.289

Neutral Organics : Daphnid ChV 412.807

Neutral Organics : Green Algae ChV 329.329

Neutral Organics : Fish (SW) 96-hr LC50 24391.777

Neutral Organics : Mysid 96-hr LC50 1.19e+005

Neutral Organics : Fish (SW) ChV 484.236

Neutral Organics : Mysid (SW) ChV 23526.172

Neutral Organics : Earthworm 14-day LC50 257.073

Note: * = asterisk designates: Chemical may not be soluble enough to

 measure this predicted effect. If the effect level exceeds the

 water solubility by 10X, typically no effects at saturation (NES)

 are reported.

------------------------------

Class Specific LogKow Cut-Offs

------------------------------

If the log Kow of the chemical is greater than the endpoint specific cut-offs

presented below, then no effects at saturation are expected for those endpoints.

Neutral Organics:

----------------

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50, Mysid LC50)

Maximum LogKow: 6.0 (Fish 14-day LC50; Earthworm LC50)

Maximum LogKow: 6.4 (Green Algae EC50)

Maximum LogKow: 8.0 (ChV)

ECOSAR Version 1.10 Results Page—Dipropylene Glycol

SMILES : CC(O)COCC(O)C

CHEM : Propanol, oxybisCAS Num: 025265-71-8

ChemID1: 

MOL FOR: C6 H14 O3 

MOL WT : 134.18

Log Kow: -0.639 (EPISuite Kowwin v1.68 Estimate)

Log Kow: (User Entered)

Log Kow: (PhysProp DB exp value - for comparison only)

Melt Pt: (User Entered for Wat Sol estimate)

Melt Pt: -40.00 (deg C, PhysProp DB exp value for Wat Sol est, <-40)

Wat Sol: 1E+006 (mg/L, EPISuite WSKowwin v1.43 Estimate)

Wat Sol: (User Entered)

Wat Sol: 1E+006 (mg/L, PhysProp DB exp value)

--------------------------------------

Values used to Generate ECOSAR Profile

--------------------------------------

Log Kow: -0.639 (EPISuite Kowwin v1.68 Estimate)

Wat Sol: 1E+006 (mg/L, PhysProp DB exp value)
Page 54 of 58

------------------------------------------------

Available Measured Data from ECOSAR Training Set

------------------------------------------------

 No Data Available

--------------------------------------

ECOSAR v1.1 Class-specific Estimations

--------------------------------------

Neutral Organics

 Predicted

ECOSAR Class Organism Duration End Pt mg/L (ppm)

=========================== ================== ======== ====== ==========

Neutral Organics : Fish 96-hr LC50 25833.533

Neutral Organics : Fish 14-day LC50 23787.684

Neutral Organics : Daphnid 48-hr LC50 11541.943

Neutral Organics : Green Algae 96-hr EC50 7567.450

Neutral Organics : Fish ChV 1894.386

Neutral Organics : Daphnid ChV 569.086

Neutral Organics : Green Algae ChV 476.003

Neutral Organics : Fish (SW) 96-hr LC50 32012.744

Neutral Organics : Mysid 96-hr LC50 1.42e+005

Neutral Organics : Fish (SW) ChV 693.606

Neutral Organics : Mysid (SW) ChV 26857.861

Neutral Organics : Earthworm 14-day LC50 438.047

Note: * = asterisk designates: Chemical may not be soluble enough to

 measure this predicted effect. If the effect level exceeds the

 water solubility by 10X, typically no effects at saturation (NES)

 are reported.

------------------------------

Class Specific LogKow Cut-Offs

------------------------------

If the log Kow of the chemical is greater than the endpoint specific cut-offs

presented below, then no effects at saturation are expected for those endpoints.

Neutral Organics:

----------------

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50, Mysid LC50)

Maximum LogKow: 6.0 (Fish 14-day LC50; Earthworm LC50)

Maximum LogKow: 6.4 (Green Algae EC50)

Maximum LogKow: 8.0 (ChV)

------------------------------------------------------------------------------
Page 55 of 58

Appendix D Ecotoxicology Profile for 

Triethylene Glycol

Toxicity to Terrestrial Animals

Avian acute oral and dietary toxicity

To establish the toxicity of triethylene glycol to birds, the Agency required an acute oral toxicity 

study using the technical grade of the active ingredient (TGAI). The preferred test species was 

either mallard duck (a waterfowl) or bobwhite quail (an upland game bird). The results of 

submitted studies are provided in the following table . The results indicate that triethylene glycol 

is practically non-toxic to birds on an acute oral basis. The studies are acceptable and fulfill 

guideline requirements (71-1/OPPTS 850.2100).

Mammals

Triethylene glycol shows low acute toxicity to mammals in laboratory studies (see Table 

Appendix A).

Table 25 Toxicity of Triethylene Glycol to Mammals (excerpted from Appendix A)

Species Test Type Results

Rat Acute oral LD50 15,000 - 22,000 mg/kg-bw (Toxicity Category IV)

Toxicity to Aquatic Receptors

Freshwater Fish, Acute

The results indicate that triethylene glycol is practically non-toxic to freshwater fish on an acute 

basis. Since these data are supplemental information, Guideline 72-1/850.1075 is not fulfilled; 

however, because multiple published studies demonstrate very low toxicity to freshwater fish for 

the glcols, no further testing is anticipated to be required for triethylene glycol at this time.

Table 26 Acute Toxicity of Triethylene Glycol to Freshwater Fish

Species Endpoints Toxicity Category Reference

Bluegill sunfish (Lepomis 

macrochirus) 96 hr LC50 = 10,000 ppm Practically non-toxic Verschuren, 1983

Fathead minnow 

(Pimephales promelas)

96 hr LC50 = 59,900 – 77,400 

ppm Practically non-toxic Geiger et al., 1988
Page 56 of 58

Freshwater Invertebrates, Acute

The Agency requires a freshwater aquatic invertebrate toxicity study using the TGAI to establish 

the acute toxicity of an antimicrobial pesticide to freshwater invertebrates. The preferred test 

species is Daphnia magna.

No data have been submitted for triethylene glycol and no data was found in the EPA/ORD 

ECOTOX database. An estimate of triethylene gylcol (neutral organics class) acute toxicity 

using ECOSAR v1.10 is 116,000 mg/L for a freshwater daphnid (see ECOSAR results page at 

end of this appendix). Triethylene glycol is expected to be practically nontoxic on an acute basis 

to freshwater invertebrates. No additional acute data are anticipated to be required for the 

assessment.

Estuarine and Marine Organisms, Acute Toxicity

Acute toxicity testing with estuarine and marine organisms (a fish, a mollusk, and a shrimp) 

using the TGAI is required when the end-use product is intended for direct application to the 

marine/estuarine environment or effluent containing the active ingredient is expected to reach 

this environment. The triethylene glycol uses are not expected to result in such exposure. 

Therefore, testing with marine/estuarine organisms is not anticipated to be required. However, a 

sheepshead minnow study and a mysid study were conducted by EPA (Mayer, 1986). 

Additionally, the acute toxicity of triethylene glycol to another fish species (Inland silverside) 

was found in ECOTOX, and the results are provided in Table 27. Triethylene glycol is 

practically nontoxic to estuarine/marine fish and invertebrates based on this data. No additional 

acute data are anticipated to be required for the assessment.

Table 27 Open Literature Estuarine/Marine Fish and Invertebrate Acute Toxicity Data for 

Triethylene Glycol

Species Endpoints Toxicity Category Reference

Sheepshead minnow 

(Cyprinodon variegatus) 96 hr LC50 = 48,000 ppm Practically non-toxic Mayer, 1986MRID 40228401

Inland silverside

Menidia beryllina 96 hr LC50 = 10,000 ppm Practically non-toxic Verschuren, 1983

Mysid (Mysidopsis bahia) 96 hr LC50 = 11,000 ppm Practically non-toxic Mayer, 1986

MRID # 40228401

Aquatic Animals, Chronic Toxicity

There are no submitted chronic data in the files and no comparable endpoints were found in the 

open literature ECOTOX database. Estimates of triethylene gylcol (neutral organics class) 

chronic toxicity to aquatic animals using ECOSAR v1.10 range from 4,288 to 18,640 mg/L for 

freshwater animals and 3,885 to 873,000 mg/L for saltwater animals (Table 28). The model 

appears to underestimate chronic toxicity to aquatic animals. There is a laboratory acute study 

for a mysid with a 96-hr LC50 (concentration at which 50% of exposed organisms are expected to 

die) of 11,000 ppm but the modeled chronic value is 873,000 ppm, which is not appropriate. 

Chronic toxicity testing (Fish early life stage, 850.1300/72-4a and aquatic invertebrate life cycle, 

850.1400/72-4b) is not anticipated to be required for the currently registered uses of triethylene

glycol. 
Page 57 of 58

Table 28 Chronic Toxicity of Triethylene Glycol to Aquatic Animals

Species Triethylene Glycol Chv Reference

Fish, Freshwater 18,640 mg/La ECOSAR v1.10

Daphnid, Freshwater Invertebrate 4,288 mg/L ECOSAR v1.10

Fish, Saltwater 3,885 mg/L ECOSAR v1.10

Mysid, Estuarine/Marine Invertebrate 873,000 mg/Lb ECOSAR v1.10

Chv = geometric mean of a NOEC and LOEC value b Model may not be appropriate for triethylene gylcol as the laboratory acute 96-hr LC50 values for freshwater fish of 

10,000 to 77,400 ppm is lower than the modeled 96-hr LC50 value for freshwater fish of 287,000 ppm (see Table 

27). b Model is not appropriate for triethylene gylcol as the chronic value is above the laboratory 96-hr LC50 value of 

11,000 ppm (see Table 27).

Toxicity to Plants

No data, such as phytotoxicity, were available from submitted studies or open literature to 

address the risk to plants. Estimates for toxicity to green algae for triethylene gylcol, as a neutral 

organic, from ECOSAR v1.10 consist of a 96-h IC50 value of 67,639 mg/L and a Chv (geometric 

mean of a NOEC and LOEC) value of 2,486 mg/L. This information is sufficient for any hazard 

labeling. Additionally, exposure to plants is not expected from the current registered uses of 

triethylene glycol. Therefore, plant toxicity testing is not anticipated to be required at this time.

ECOSAR Version 1.10 Results Page – Triethylene Glycol

SMILES : O(CCOCCO)CCO

CHEM : Ethanol, 2,2 -[1,2-ethanediylbis(oxy)]bisCAS Num: 000112-27-6

ChemID1: 

MOL FOR: C6 H14 O4 

MOL WT : 150.18

Log Kow: -1.748 (EPISuite Kowwin v1.68 Estimate)

Log Kow: (User Entered)

Log Kow: -1.75 (PhysProp DB exp value - for comparison only)

Melt Pt: (User Entered for Wat Sol estimate)

Melt Pt: -7.00 (deg C, PhysProp DB exp value for Wat Sol est)

Wat Sol: 1E+006 (mg/L, EPISuite WSKowwin v1.43 Estimate)

Wat Sol: (User Entered)

Wat Sol: 1E+006 (mg/L, PhysProp DB exp value)

--------------------------------------

Values used to Generate ECOSAR Profile

--------------------------------------

Log Kow: -1.748 (EPISuite Kowwin v1.68 Estimate)

Wat Sol: 1E+006 (mg/L, PhysProp DB exp value)

------------------------------------------------

Available Measured Data from ECOSAR Training Set

------------------------------------------------
Page 58 of 58

 Measured

CAS No Organism Duration End Pt mg/L (ppm) Ecosar Class 

Reference

=========== ========== ========== ====== ========== =========================== 

=========================

000112-27-6 Fish 96-hr LC50 59900 Neutral organics DUL

000112-27-6 Fish 96-hr LC50 70200 Neutral organics DUL

000112-27-6 Fish 96-hr LC50 77400 Neutral organics DUL

000112-27-6 Fish 14-day LC50 62601.4 Neutral organics 

Konemann, 1981

--------------------------------------

ECOSAR v1.1 Class-specific Estimations

--------------------------------------

Neutral Organics

 Predicted

ECOSAR Class Organism Duration End Pt mg/L (ppm)

=========================== ================== ======== ====== ==========

Neutral Organics : Fish 96-hr LC50 2.87e+005

Neutral Organics : Fish 14-day LC50 2.51e+005

Neutral Organics : Daphnid 48-hr LC50 1.16e+005

Neutral Organics : Green Algae 96-hr EC50 67639.422

Neutral Organics : Fish ChV 18639.736

Neutral Organics : Daphnid ChV 4288.514

Neutral Organics : Green Algae ChV 2486.059

Neutral Organics : Fish (SW) 96-hr LC50 3.53e+005

Neutral Organics : Mysid 96-hr LC50 3.32e+006 *

Neutral Organics : Fish (SW) ChV 3885.237

Neutral Organics : Mysid (SW) ChV 8.73e+005

Neutral Organics : Earthworm 14-day LC50 639.014

Note: * = asterisk designates: Chemical may not be soluble enough to

 measure this predicted effect. If the effect level exceeds the

 water solubility by 10X, typically no effects at saturation (NES)

 are reported.

------------------------------

Class Specific LogKow Cut-Offs

------------------------------

If the log Kow of the chemical is greater than the endpoint specific cut-offs

presented below, then no effects at saturation are expected for those endpoints.

Neutral Organics:

----------------

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50, Mysid LC50)

Maximum LogKow: 6.0 (Fish 14-day LC50; Earthworm LC50)

Maximum LogKow: 6.4 (Green Algae EC50)

Maximum LogKow: 8.0 (ChV)

------------------------------------------------------------------------------