TOXICOLOGICAL PROFILE FOR
 

ETHYLENE GLYCOL
 


 


 


 


 

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
 

Public Health Service
 

Agency for Toxic Substances and Disease Registry
 

November 2010 
 

ETHYLENE GLYCOL ii 

DISCLAIMER 

The use of company or product name(s) is for identification only and does not imply endorsement by the 

Agency for Toxic Substances and Disease Registry. 
 

ETHYLENE GLYCOL iii 

UPDATE STATEMENT
 

A Toxicological Profile for Ethylene Glycol, Draft for Public Comment was released in October 2007. 

This edition supersedes any previously released draft or final profile. 

Toxicological profiles are revised and republished as necessary. For information regarding the update 

status of previously released profiles, contact ATSDR at: 

Agency for Toxic Substances and Disease Registry
 

Division of Toxicology and Environmental Medicine/Applied Toxicology Branch
 

1600 Clifton Road NE
 

Mailstop F-62
 

Atlanta, Georgia 30333
 
ETHYLENE GLYCOL iv 

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FOREWORD 


This toxicological profile is prepared in accordance with guidelines* developed by the Agency for 

Toxic Substances and Disease Registry (ATSDR) and the Environmental Protection Agency (EPA). The 

original guidelines were published in the Federal Register on April 17, 1987. Each profile will be revised 

and republished as necessary. 

The ATSDR toxicological profile succinctly characterizes the toxicologic and adverse health 

effects infonnation for these toxic substances described therein. Each peer-reviewed profile identifies and 

reviews the key literature that describes a substance's toxicologic properties. Other pertinent literature is 

also presented, but is described in less detail than the key studies. The profile is not intended to be an 

exhaustive document; however, more comprehensive sources of specialty information are referenced. 

The focus ofthe profiles is on health and toxicologic infonnation; therefore, each toxicological 

profile begins with a public health statement that describes, in nontechnical language, a substance's 

relevant toxicological properties. Following the public health statement is infonnation concerning levels 

of significant human exposure and, where known, significant health effects. The adequacy of infonnation 

to detennine a substance's health effects is described in a health effects summary. Data needs that are of 

significance to protection of public health are identified by ATSDR. 

Each profile includes the following: 

(A) The examination, summary, and interpretation ofavailable toxicologic infonnation and 

epidemiologic evaluations on a toxic substance to ascertain the levels of significant human 

exposure for the substance and the associated acute, subacute, and chronic health effects; 

(B) 	A determination ofwhether adequate infonnation on the health effects of each substance is 

available or in the process of development to detennine levels ofexposure that present a 

significant risk to human health ofacute, subacute, and chronic health effects; and 

(C) Where appropriate, identification oftoxicologic testing needed to identifY the types or levels 

ofexposure that may present significant risk of adverse health effects in humans. 

The principal audiences for the toxicological profiles are health professionals at the Federal, State, 

and local levels; interested private sector organizations and groups; and members ofthe public. 

This profile reflects ATSDR's assessment ofall relevant toxicologic testing and infonnation that 

has been peer-reviewed. Staffs ofthe Centers for Disease Control and Prevention and other Federal 

scientists have also reviewed the profile. In addition, this profile has been peer-reviewed by a 

nongovernmental panel and was made available for public review. Final responsibility for the contents 

and views expressed in this toxicological profile resides with ATSDR. 

// 7\\ /) ;/A~-'0/.L.-- /r:../C~--(Xj 

Thomas R. Frieden, M.D., M.P.H. 


Administrator 


Agency for Toxic Substances and 


Disease Registry 

"Legislative Background 

The toxicological profiles are developed under the Comprehensive Environmental Response, 

Compensation, and Liability Act of 1980, as amended (CERCLA or Superfund). CERCLA section 

104(i)(1) directs the Administrator of ATSDR to " ...effectuate and implement the health related 

authorities" ofthe statute. This includes the preparation oftoxicological profiles for hazardous 

substances most commonly found at facilities on the CERCLA National Priorities List and that pose the 

most significant potential threat to human health, as determined by ATSDR and the EPA. Section 

104(i)(3) ofCERCLA, as amended, directs the Administrator ofATSDR to prepare a toxicological profile 

for each substance on the list. In addition, A TSDR has the authority to prepare toxicological profiles for 

substances not found at sites on the National Priorities List, in an effort to " ...establish and maintain 

inventory of literature, research, and studies on the health effects oftoxic substances" under CERCLA 

Section 104(i)(IXB), to respond to requests for consultation under section 104(i)(4), and as otherwise 

necessary to support the site-specific response actions conducted by A TSDR. 
 

 

 

 

 

 

ETHYLENE GLYCOL vii 

QUICK REFERENCE FOR HEALTH CARE PROVIDERS 

Toxicological Profiles are a unique compilation of toxicological information on a given hazardous 

substance. Each profile reflects a comprehensive and extensive evaluation, summary, and interpretation 

of available toxicologic and epidemiologic information on a substance. Health care providers treating 

patients potentially exposed to hazardous substances will find the following information helpful for fast 

answers to often-asked questions. 

Primary Chapters/Sections of Interest 

Chapter 1: Public Health Statement: The Public Health Statement can be a useful tool for educating 

patients about possible exposure to a hazardous substance. It explains a substance’s relevant 

toxicologic properties in a nontechnical, question-and-answer format, and it includes a review of 

the general health effects observed following exposure. 

Chapter 2: Relevance to Public Health: The Relevance to Public Health Section evaluates, interprets, 

and assesses the significance of toxicity data to human health. 

Chapter 3: Health Effects: Specific health effects of a given hazardous compound are reported by type 

of health effect (death, systemic, immunologic, reproductive), by route of exposure, and by length 

of exposure (acute, intermediate, and chronic). In addition, both human and animal studies are 

reported in this section. 

NOTE: Not all health effects reported in this section are necessarily observed in the clinical 

setting. Please refer to the Public Health Statement to identify general health effects observed 

following exposure. 

Pediatrics: Four new sections have been added to each Toxicological Profile to address child health 

issues: 

Section 1.6 How Can (Chemical X) Affect Children?
 

Section 1.7 How Can Families Reduce the Risk of Exposure to (Chemical X)?
 

Section 3.7 Children’s Susceptibility
 

Section 6.6 Exposures of Children
 

Other Sections of Interest: 

Section 3.8 Biomarkers of Exposure and Effect 

Section 3.11 Methods for Reducing Toxic Effects 

ATSDR Information Center 

Phone: 1-800-CDC-INFO (800-232-4636) or 1-888-232-6348 (TTY) Fax: (770) 488-4178 

E-mail: cdcinfo@cdc.gov Internet: http://www.atsdr.cdc.gov 

The following additional material can be ordered through the ATSDR Information Center: 

Case Studies in Environmental Medicine: Taking an Exposure History—The importance of taking an 

exposure history and how to conduct one are described, and an example of a thorough exposure 

history is provided. Other case studies of interest include Reproductive and Developmental 

Hazards; Skin Lesions and Environmental Exposures; Cholinesterase-Inhibiting Pesticide 

Toxicity; and numerous chemical-specific case studies. 
 

 

 

 

 

 

 

ETHYLENE GLYCOL viii 

Managing Hazardous Materials Incidents is a three-volume set of recommendations for on-scene 

(prehospital) and hospital medical management of patients exposed during a hazardous materials 

incident. Volumes I and II are planning guides to assist first responders and hospital emergency 

department personnel in planning for incidents that involve hazardous materials. Volume III— 

Medical Management Guidelines for Acute Chemical Exposures—is a guide for health care 

professionals treating patients exposed to hazardous materials. 

Fact Sheets (ToxFAQs) provide answers to frequently asked questions about toxic substances. 

Other Agencies and Organizations 

The National Center for Environmental Health (NCEH) focuses on preventing or controlling disease, 

injury, and disability related to the interactions between people and their environment outside the 

workplace. Contact: NCEH, Mailstop F-29, 4770 Buford Highway, NE, Atlanta, 

GA 30341-3724 • Phone: 770-488-7000 • FAX: 770-488-7015. 

The National Institute for Occupational Safety and Health (NIOSH) conducts research on occupational 

diseases and injuries, responds to requests for assistance by investigating problems of health and 

safety in the workplace, recommends standards to the Occupational Safety and Health 

Administration (OSHA) and the Mine Safety and Health Administration (MSHA), and trains 

professionals in occupational safety and health. Contact: NIOSH, 200 Independence Avenue, 

SW, Washington, DC 20201 • Phone: 800-356-4674 or NIOSH Technical Information Branch, 

Robert A. Taft Laboratory, Mailstop C-19, 4676 Columbia Parkway, Cincinnati, OH 45226-1998 

• Phone: 800-35-NIOSH. 

The National Institute of Environmental Health Sciences (NIEHS) is the principal federal agency for 

biomedical research on the effects of chemical, physical, and biologic environmental agents on 

human health and well-being. Contact: NIEHS, PO Box 12233, 104 T.W. Alexander Drive, 

Research Triangle Park, NC 27709 • Phone: 919-541-3212. 

Referrals 

The Association of Occupational and Environmental Clinics (AOEC) has developed a network of clinics 

in the United States to provide expertise in occupational and environmental issues. Contact: 

AOEC, 1010 Vermont Avenue, NW, #513, Washington, DC 20005 • Phone: 202-347-4976 

• FAX: 202-347-4950 • e-mail: AOEC@AOEC.ORG • Web Page: http://www.aoec.org/. 

The American College of Occupational and Environmental Medicine (ACOEM) is an association of 

physicians and other health care providers specializing in the field of occupational and 

environmental medicine. Contact: ACOEM, 25 Northwest Point Boulevard, Suite 700, Elk 

Grove Village, IL 60007-1030 • Phone: 847-818-1800 • FAX: 847-818-9266. 
ETHYLENE GLYCOL ix 

CONTRIBUTORS 

CHEMICAL MANAGER(S)/AUTHOR(S): 

Obaid Faroon, D.V.M., Ph.D.
 

Carolyn Tylenda, D.M.D., Ph.D.
 

Carolyn C. Harper, M.S., Ph.D.
 

Dianyi Yu, M.D., Ph.D.
 

Amanda Cadore, M.P.H.
 

ATSDR, Division of Toxicology and Environmental Medicine, Atlanta, GA
 

Stephen Bosch, B.S.
 

David Wohlers, Ph.D.
 

Daniel Plewak, B.S.
 

Heather Carlson-Lynch, S.M.
 

SRC, Inc., North Syracuse, NY
 

THE PROFILE HAS UNDERGONE THE FOLLOWING ATSDR INTERNAL REVIEWS: 

1.	 Health Effects Review. The Health Effects Review Committee examines the health effects 

chapter of each profile for consistency and accuracy in interpreting health effects and classifying 

end points. 

2.	 Minimal Risk Level Review. The Minimal Risk Level Workgroup considers issues relevant to 

substance-specific Minimal Risk Levels (MRLs), reviews the health effects database of each 

profile, and makes recommendations for derivation of MRLs. 

3.	 Data Needs Review. The Applied Toxicology Branch reviews data needs sections to assure 

consistency across profiles and adherence to instructions in the Guidance. 

4.	 Green Border Review. Green Border review assures the consistency with ATSDR policy. 
ETHYLENE GLYCOL x 

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ETHYLENE GLYCOL xi 

PEER REVIEW
 

A peer review panel was assembled for ethylene glycol. The panel consisted of the following members: 

Draft for Public Comment: 

1.	 Phillip Goad, Ph.D., Center for Toxicology and Environmental Health, LLC, North Little Rock, 

Arkansas; 

2.	 Jerrold Leikin, M.D., ENH-OMEGA, Glenview, Illinois; and 

3.	 Kenneth McMartin, Ph.D., Louisiana State University, Shreveport, Louisiana. 

These experts collectively have knowledge of ethylene glycol's physical and chemical properties, 

toxicokinetics, key health end points, mechanisms of action, human and animal exposure, and 

quantification of risk to humans. All reviewers were selected in conformity with the conditions for peer 

review specified in Section 104(I)(13) of the Comprehensive Environmental Response, Compensation, 

and Liability Act, as amended. 

Scientists from the Agency for Toxic Substances and Disease Registry (ATSDR) have reviewed the peer 

reviewers' comments and determined which comments will be included in the profile. A listing of the 

peer reviewers' comments not incorporated in the profile, with a brief explanation of the rationale for their 

exclusion, exists as part of the administrative record for this compound. 

The citation of the peer review panel should not be understood to imply its approval of the profile's final 

content. The responsibility for the content of this profile lies with the ATSDR. 
ETHYLENE GLYCOL xii 

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ETHYLENE GLYCOL xiii 

CONTENTS
 

DISCLAIMER ..............................................................................................................................................ii
 

UPDATE STATEMENT .............................................................................................................................iii
 

FOREWORD ................................................................................................................................................v
 

QUICK REFERENCE FOR HEALTH CARE PROVIDERS....................................................................vii
 

CONTRIBUTORS.......................................................................................................................................ix
 

PEER REVIEW ...........................................................................................................................................xi
 

CONTENTS...............................................................................................................................................xiii
 

LIST OF FIGURES ..................................................................................................................................xvii
 

LIST OF TABLES.....................................................................................................................................xix
 

1. PUBLIC HEALTH STATEMENT..........................................................................................................1
 

1.1 WHAT IS ETHYLENE GLYCOL?...............................................................................................1
 

1.2 WHAT HAPPENS TO ETHYLENE GLYCOL WHEN IT ENTERS THE
 

ENVIRONMENT?.........................................................................................................................2
 

1.3 HOW MIGHT I BE EXPOSED TO ETHYLENE GLYCOL? ......................................................2
 

1.4 HOW CAN ETHYLENE GLYCOL ENTER AND LEAVE MY BODY? ...................................3
 

1.5 HOW CAN ETHYLENE GLYCOL AFFECT MY HEALTH? ....................................................3
 

1.6 HOW CAN ETHYLENE GLYCOL AFFECT CHILDREN? .......................................................4
 

1.7 HOW CAN FAMILIES REDUCE THE RISK OF EXPOSURE TO ETHYLENE 

GLYCOL?......................................................................................................................................4
 

1.8 IS THERE A MEDICAL TEST TO DETERMINE WHETHER I HAVE BEEN EXPOSED
 

TO ETHYLENE GLYCOL?..........................................................................................................5
 

1.9 WHAT RECOMMENDATIONS HAS THE FEDERAL GOVERNMENT MADE TO 

PROTECT HUMAN HEALTH? ...................................................................................................5
 

1.10 WHERE CAN I GET MORE INFORMATION?..........................................................................6
 

2. RELEVANCE TO PUBLIC HEALTH ...................................................................................................9
 

2.1 BACKGROUND AND ENVIRONMENTAL EXPOSURES TO ETHYLENE GLYCOL
 

IN THE UNITED STATES ...........................................................................................................9
 

2.2 SUMMARY OF HEALTH EFFECTS......................................................................................... 10
 

2.3 MINIMAL RISK LEVELS (MRLs) ............................................................................................16
 

3. HEALTH EFFECTS..............................................................................................................................39
 

3.1 INTRODUCTION........................................................................................................................39
 

3.2 DISCUSSION OF HEALTH EFFECTS BY ROUTE OF EXPOSURE .....................................39
 

3.2.1 Inhalation Exposure ..............................................................................................................41
 

3.2.1.1 Death..............................................................................................................................41
 

3.2.1.2 Systemic Effects.............................................................................................................41
 

3.2.1.3 Immunological and Lymphoreticular Effects................................................................46
 

3.2.1.4 Neurological Effects ......................................................................................................46
 

3.2.1.5 Reproductive Effects......................................................................................................47
 

3.2.1.6 Developmental Effects...................................................................................................48
 

3.2.1.7 Cancer............................................................................................................................49
 

3.2.2 Oral Exposure........................................................................................................................49
 

3.2.2.1 Death..............................................................................................................................49
 

3.2.2.2 Systemic Effects.............................................................................................................51
 

3.2.2.3 Immunological and Lymphoreticular Effects..............................................................100
 

3.2.2.4 Neurological Effects ....................................................................................................102
 

3.2.2.5 Reproductive Effects....................................................................................................104
 
 

ETHYLENE GLYCOL xiv 

3.2.2.6 Developmental Effects.................................................................................................107
 

3.2.2.7 Cancer..........................................................................................................................111
 

3.2.3 Dermal Exposure.................................................................................................................111
 

3.2.3.1 Death............................................................................................................................111
 

3.2.3.2 Systemic Effects...........................................................................................................112
 

3.2.3.3 Immunological and Lymphoreticular Effects..............................................................112
 

3.2.3.4 Neurological Effects ....................................................................................................114
 

3.2.3.5 Reproductive Effects....................................................................................................114
 

3.2.3.6 Developmental Effects.................................................................................................114
 

3.2.3.7 Cancer..........................................................................................................................115
 

3.3 GENOTOXICITY......................................................................................................................115
 

3.4 TOXICOKINETICS...................................................................................................................117
 

3.4.1 Absorption...........................................................................................................................117
 

3.4.1.1 Inhalation Exposure .....................................................................................................117
 

3.4.1.2 Oral Exposure ..............................................................................................................118
 

3.4.1.3 Dermal Exposure .........................................................................................................119
 

3.4.2 Distribution .........................................................................................................................119
 

3.4.2.1 Inhalation Exposure .....................................................................................................119
 

3.4.2.2 Oral Exposure ..............................................................................................................119
 

3.4.2.3 Dermal Exposure .........................................................................................................120
 

3.4.3 Metabolism..........................................................................................................................123
 

3.4.4 Elimination and Excretion...................................................................................................127
 

3.4.4.1 Inhalation Exposure ..................................................................................................... 127
 

3.4.4.2 Oral Exposure ..............................................................................................................127
 

3.4.4.3 Dermal Exposure .........................................................................................................130
 

3.4.5 Physiologically Based Pharmacokinetic (PBPK)/Pharmacodynamic (PD) Models...........130
 

3.5 MECHANISMS OF ACTION ...................................................................................................137
 

3.5.1 Pharmacokinetic Mechanisms.............................................................................................137
 

3.5.2 Mechanisms of Toxicity......................................................................................................138
 

3.5.3 Animal-to-Human Extrapolations.......................................................................................142
 

3.6 TOXICITIES MEDIATED THROUGH THE NEUROENDOCRINE AXIS...........................142
 

3.7 CHILDREN’S SUSCEPTIBILITY............................................................................................143
 

3.8 BIOMARKERS OF EXPOSURE AND EFFECT .....................................................................148
 

3.8.1 Biomarkers Used to Identify or Quantify Exposure to Ethylene Glycol.............................149
 

3.8.2 Biomarkers Used to Characterize Effects Caused by Ethylene Glycol...............................150
 

3.9 INTERACTIONS WITH OTHER CHEMICALS .....................................................................152
 

3.10 POPULATIONS THAT ARE UNUSUALLY SUSCEPTIBLE ............................................152
 

3.11 METHODS FOR REDUCING TOXIC EFFECTS................................................................153
 

3.11.1 Reducing Peak Absorption Following Exposure.............................................................153
 

3.11.2 Reducing Body Burden ...................................................................................................154
 

3.11.3 Interfering with the Mechanism of Action for Toxic Effects..........................................156
 

3.12 ADEQUACY OF THE DATABASE.....................................................................................156
 

3.12.1 Existing Information on Health Effects of ethylene glycol.............................................156
 

3.12.2 Identification of Data Needs............................................................................................158
 

3.12.3 Ongoing Studies ..............................................................................................................173
 

4. CHEMICAL AND PHYSICAL INFORMATION..............................................................................175
 

4.1 CHEMICAL IDENTITY............................................................................................................175
 

4.2 PHYSICAL AND CHEMICAL PROPERTIES......................................................................... 175
 
 

 

 

 

 

ETHYLENE GLYCOL xv 

5. PRODUCTION, IMPORT/EXPORT, USE, AND DISPOSAL..........................................................179
 

5.1 PRODUCTION ..........................................................................................................................179
 

5.2 IMPORT/EXPORT ....................................................................................................................183
 

5.3 USE ............................................................................................................................................183
 

5.4 DISPOSAL.................................................................................................................................185
 

6. POTENTIAL FOR HUMAN EXPOSURE .........................................................................................187
 

6.1 OVERVIEW...............................................................................................................................187
 

6.2 RELEASES TO THE ENVIRONMENT...................................................................................189
 

6.2.1 Air .......................................................................................................................................189
 

6.2.2 Water...................................................................................................................................192
 

6.2.3 Soil ......................................................................................................................................192
 

6.3 ENVIRONMENTAL FATE ......................................................................................................193
 

6.3.1 Transport and Partitioning...................................................................................................193
 

6.3.2 Transformation and Degradation ........................................................................................194
 

6.3.2.1 Air................................................................................................................................194
 

6.3.2.2 Water............................................................................................................................194
 

6.3.2.3 Sediment and Soil ........................................................................................................195
 

6.4 LEVELS MONITORED OR ESTIMATED IN THE ENVIRONMENT..................................196
 

6.4.1 Air .......................................................................................................................................196
 

6.4.2 Water...................................................................................................................................197
 

6.4.3 Sediment and Soil ...............................................................................................................198
 

6.4.4 Other Environmental Media................................................................................................198
 

6.5 GENERAL POPULATION AND OCCUPATIONAL EXPOSURE ........................................ 198
 

6.6 EXPOSURES OF CHILDREN..................................................................................................200
 

6.7 POPULATIONS WITH POTENTIALLY HIGH EXPOSURES ..............................................201
 

6.8 ADEQUACY OF THE DATABASE ........................................................................................201
 

6.8.1 Identification of Data Needs ...............................................................................................202
 

6.8.2 Ongoing Studies..................................................................................................................205
 

7. ANALYTICAL METHODS................................................................................................................207
 

7.1 BIOLOGICAL MATERIALS....................................................................................................207
 

7.2 ENVIRONMENTAL SAMPLES ..............................................................................................212
 

7.3 ADEQUACY OF THE DATABASE ........................................................................................215
 

7.3.1 Identification of Data Needs ...............................................................................................215
 

7.3.2 Ongoing Studies..................................................................................................................216
 

8. REGULATIONS, ADVISORIES, AND GUIDELINES.....................................................................217
 

9. REFERENCES ....................................................................................................................................221
 

10. GLOSSARY ......................................................................................................................................249
 

APPENDICES 

A. ATSDR MINIMAL RISK LEVELS AND WORKSHEETS .............................................................A-1
 

B. USER’S GUIDE.................................................................................................................................. B-1
 

C. ACRONYMS, ABBREVIATIONS, AND SYMBOLS...................................................................... C-1
 

D. INDEX ................................................................................................................................................D-1
 
ETHYLENE GLYCOL xvi 

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ETHYLENE GLYCOL xvii 

LIST OF FIGURES
 

3-1. Levels of Significant Exposure to Ethylene Glycol - Inhalation ........................................................ 43
 

3-2. Levels of Significant Exposure to Ethylene Glycol - Oral ................................................................. 81
 

3-3. Metabolic Pathway for Ethylene Glycol...........................................................................................124
 

3-4. Conceptual Representation of a Physiologically Based Pharmacokinetic (PBPK) Model for a
 

Hypothetical Chemical Substance....................................................................................................132
 

3-5. Existing Information on Health Effects of Ethylene Glycol.............................................................157
 

6-1. Frequency of NPL Sites with Ethylene Glycol Contamination........................................................188
 
ETHYLENE GLYCOL xviii 

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ETHYLENE GLYCOL xix 

LIST OF TABLES
 

3-1. Levels of Significant Exposure to Ethylene Glycol - Inhalation ........................................................ 42
 

3-2. Levels of Significant Exposure to Ethylene Glycol - Oral ................................................................. 52
 

3-3. Levels of Significant Exposure to Ethylene Glycol - Dermal .......................................................... 113
 

3-4. Genotoxicity of Ethylene Glycol In Vitro ........................................................................................116
 

3-5. Distribution of Radioactivity (Percent of Administered Dose) in Tissues 96 Hours After Oral
 

or Percutaneous Exposure to 14C-Ethylene Glycol ..........................................................................121
 

3-6. Radioactivity (Percent of Administered Dose) in Excreta 96 Hours After 6-Hour Occluded 

Percutaneous Exposure to 14C-Ethylene Glycol...............................................................................122
 

3-7. Radioactivity (Percent of Administered Dose) in Excreta 96 Hours After Oral or Exposure to 

14C-Ethylene Glycol.........................................................................................................................129
 

3-8. Physiological Parameters in PBPK Models for Ethylene Glycol.....................................................134
 

3-9. Biochemical Parameters in PBPK Models for Ethylene Glycol.......................................................135
 

4-1. Chemical Identity of Ethylene Glycol ..............................................................................................176
 

4-2. Physical and Chemical Properties of Ethylene Glycol.....................................................................177
 

5-1. Companies that Produce Ethylene Glycol in the United States and Annual Capacities
 

During 2008 .....................................................................................................................................180
 

5-2. Facilities that Produce, Process, or Use Ethylene Glycol.................................................................181
 

5-3. U.S. Ethylene Glycol Imports and Exports by Year in Metric Tons................................................184
 

6-1. Releases to the Environment from Facilities that Produce, Process, or Use Ethylene Glycol .........190
 

7-1. Analytical Methods for Determining Ethylene Glycol in Biological Materials...............................208
 

7-2. Analytical Methods for Determining Ethylene Glycol in Environmental Samples .........................213
 

8-1. Regulations, Advisories, and Guidelines Applicable to Ethylene Glycol ........................................219
 
ETHYLENE GLYCOL xx 

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ETHYLENE GLYCOL 1 

1. PUBLIC HEALTH STATEMENT 

This public health statement tells you about ethylene glycol and the effects of exposure to it. 

The Environmental Protection Agency (EPA) identifies the most serious hazardous waste sites in the 

nation. These sites are then placed on the National Priorities List (NPL) and are targeted for long-term 

federal clean-up activities. Ethylene glycol has been found in at least 37 of the 1,689 current or former 

NPL sites. Although the total number of NPL sites evaluated for this substance is not known, the 

possibility exists that the number of sites at which ethylene glycol is found may increase in the future as 

more sites are evaluated. This information is important because these sites may be sources of exposure 

and exposure to this substance maybe harmful. 

When a substance is released either from a large area, such as an industrial plant, or from a container, 

such as a drum or bottle, it enters the environment. Such a release does not always lead to exposure. You 

can be exposed to a substance only when you come in contact with it. You may be exposed by breathing, 

eating, or drinking the substance, or by skin contact. 

If you are exposed to ethylene glycol, many factors will determine whether you will be harmed. These 

factors include the dose (how much), the duration (how long), and how you come in contact with it. You 

must also consider any other chemicals you are exposed to and your age, sex, diet, family traits, lifestyle, 

and state of health. 

1.1 WHAT IS ETHYLENE GLYCOL? 

Colorless liquid 

that is odorless 

Ethylene glycol is a synthetic liquid substance that absorbs water. It is 

odorless, but has a sweet taste. 

Used in 

consumer 

products 

Ethylene glycol is used to make antifreeze and de-icing solutions for cars, 

airplanes, and boats. 

Consumer products containing ethylene glycol include: 

• Antifreeze 

• Hydraulic brake fluids 

• Inks used in stamp pads, ballpoint pens, and print shops 

For more information on the sources, properties, and uses of ethylene glycol, see Chapters 4 and 5. 
 

 

 

 

 

 

ETHYLENE GLYCOL 2 

1. PUBLIC HEALTH STATEMENT 

1.2 WHAT HAPPENS TO ETHYLENE GLYCOL WHEN IT ENTERS THE ENVIRONMENT? 

Released into 

air, water, and 

soil 

The primary source of ethylene glycol in the environment is from run-off at 

airports where is used in de-icing agents for runways and airplanes. Ethylene 

glycol can also enter the environment through the disposal of products that 

contain it. 

Quickly broken 

down 

Air: Ethylene glycol in air will break down in about 10 days. 

Water and soil: Ethylene glycol in water and in soil will breakdown within 

several days to a few weeks. 

See Chapters 5 and 6 for more information on ethylene glycol in the environment. 

1.3 HOW MIGHT I BE EXPOSED TO ETHYLENE GLYCOL? 

Antifreeze The general public can be exposed to ethylene glycol through skin contact 

when using automobile antifreeze. Accidental or intentional ingestion can 

occur because antifreeze is a sweet tasting, brightly colored liquid. 

Air, water, soil Background concentrations of ethylene glycol in air, surface water, 

groundwater, drinking water, soil, and sediment have not been reported. 

Exposure to ethylene glycol in air, drinking water, or soil is not expected. 

Workplace air People who work in industries that use ethylene glycol may be exposed by 

touching products such as solvents, antifreeze, and feedstocks that contain 

this substance 

Workers can also be exposed to low levels from ethylene glycol-containing 

products such as airplane de-icing solutions that have been sprayed into the 

air. 

See Chapter 6 for more information on exposure to ethylene glycol. 
 

 

 

 

 

 

 

ETHYLENE GLYCOL 3 

1. PUBLIC HEALTH STATEMENT 

1.4 HOW CAN ETHYLENE GLYCOL ENTER AND LEAVE MY BODY? 

Enters your body 

after ingestion, 

inhalation, or 

dermal contact 

Ingested ethylene glycol is quickly absorbed in large amounts. 

There is some information suggesting that inhaled ethylene glycol is also 

absorbed. 

Ethylene glycol can also slowly enter your bloodstream through your skin if 

you come in direct contact with it and do not wash it off. 

Typically leaves 

your body within 

1–2 days 

Once in your body, most of the ethylene glycol is broken down (into other 

more toxic chemicals) and some of it remains unchanged. Ethylene glycol 

and its break down products are removed from your body through the 

excretion of urine. 

1.5 HOW CAN ETHYLENE GLYCOL AFFECT MY HEALTH? 

This section looks at studies concerning potential health effects in animal and human studies. 

Scientists use many tests to protect the public from harmful effects of toxic chemicals and to find ways 

for treating persons who have been harmed. 

One way to learn whether a chemical will harm people is to determine how the body absorbs, uses, and 

releases the chemical. For some chemicals, animal testing may be necessary. Animal testing may also 

help identify health effects such as cancer or birth defects. Without laboratory animals, scientists would 

lose a basic method for getting information needed to make wise decisions that protect the public’s health. 

Scientists have the responsibility to treat research animals with care and compassion. Scientists must 

comply with strict animal care guidelines because laws today protect the welfare of research animals. 

The effect of ethylene glycol on human health depends on how much ethylene glycol is present. 

Very small 

amounts will not 

affect your health 

Your health is not likely to be seriously affected by the very small amounts 

of ethylene glycol that could be tasted or otherwise accidentally eaten (for 

example, by putting your fingers in your mouth after getting them wet with 

antifreeze). Accidental or intentional ingestion of larger amounts of ethylene 

glycol can cause serious illness or death. 
 

 

 

 

 

 

 

ETHYLENE GLYCOL 4 

1. PUBLIC HEALTH STATEMENT 

Large amounts 

can damage the 

kidneys, nervous 

system, and heart 

When ethylene glycol breaks down in the body, it forms chemicals that 

crystallize, and the crystals can collect in your kidneys and affect kidney 

function. 

Ethylene glycol also forms acidic chemicals in the body, which can change 

the body's acid/base balance and affect your nervous system, lungs, and 

heart. 

Early treatment 

can prevent 

damage 

Treatment after early diagnosis has been very successful in people drinking 

large amounts of ethylene glycol. 

Further information on the health effects of ethylene glycol in humans and animals can be found in 

Chapters 2 and 3. 

1.6 HOW CAN ETHYLENE GLYCOL AFFECT CHILDREN? 

This section discusses potential health effects in humans from exposures during the period from 

conception to maturity at 18 years of age. 

Children are likely 

to have similar 

effects as adults 

Clinical findings in children who were poisoned by accidentally or 

intentionally drinking ethylene glycol indicate that it is likely that children 

would show the same health effects as adults. We do not know whether 

children differ in their susceptibility to the effects of ethylene glycol. 

Birth defects We do not know whether ethylene glycol causes birth defects in people. 

Skeletal defects and low birth weights have occurred in newborn animals 

whose mothers ingested large amounts of ethylene glycol during pregnancy. 

Lactation 

exposure 

We do not know whether ethylene glycol can accumulate in breast milk. 

1.7 HOW CAN FAMILIES REDUCE THE RISK OF EXPOSURE TO ETHYLENE GLYCOL? 

If your doctor finds that you have been exposed to substantial amounts of ethylene glycol, ask whether 

your children might also have been exposed. Your doctor might need to ask your state health department 

to investigate. 
 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 5 

1. PUBLIC HEALTH STATEMENT 

Avoid ingestion of Antifreeze products should be used with caution and kept out of the reach of 

antifreeze by children. Open bottles of antifreeze should not be left on or near the ground 

careful handling where children can reach them. 

and storage 

Antifreeze should not be stored in anything other than the original container, 

such as in a cup or soft drink bottle, to avoid someone mistaking it for a 

beverage. Antifreeze containers should have a child-proof cap, be stored 

away from food, and be properly marked. 

Get medical Ethylene glycol poisoning can be effectively treated, but early diagnosis is 

advice if needed to prevent serious injury. Medical attention should be sought as 

antifreeze is soon as possible in cases of known or suspected antifreeze ingestion. 

ingested 

Limit dermal 

exposure to 

products 

containing 

ethylene glycol 

Minimize skin contact when using antifreeze and other consumer products 

containing ethylene glycol. Avoid spilling or draining antifreeze on the 

ground to prevent children from playing in a puddle of ethylene glycol. 

1.8 IS THERE A MEDICAL TEST TO DETERMINE WHETHER I HAVE BEEN EXPOSED TO 

ETHYLENE GLYCOL? 

Analysis of blood 

and urine 

Ethylene glycol and its effects can be measured in blood and urine. The 

metabolites cause characteristic chemical changes in the blood and urine 

that help to diagnose ethylene glycol poisoning. 

You should have these tests done within a few hours after exposure occurs 

because ethylene glycol leaves the body very quickly and early diagnosis is 

necessary for effective treatment. 

The presence of crystals in the urine may indicate kidney damage. 

Refer to Chapters 3 and 7 for more information on these tests. 

1.9 WHAT RECOMMENDATIONS HAS THE FEDERAL GOVERNMENT MADE TO 

PROTECT HUMAN HEALTH? 

The federal government develops regulations and recommendations to protect public health. Regulations 

can be enforced by law. The EPA, the Occupational Safety and Health Administration (OSHA), and the 

Food and Drug Administration (FDA) are some federal agencies that develop regulations for toxic 

substances. Recommendations provide valuable guidelines to protect public health, but cannot be 

enforced by law. The Agency for Toxic Substances and Disease Registry (ATSDR) and the National 
 

 

 

 

 

 

 

ETHYLENE GLYCOL 6 

1. PUBLIC HEALTH STATEMENT 

Institute for Occupational Safety and Health (NIOSH) are two federal organizations that develop 

recommendations for toxic substances. 

Regulations and recommendations can be expressed as “not-to-exceed” levels. These are levels of a toxic 

substance in air, water, soil, or food that do not exceed a critical value. This critical value is usually based 

on levels that affect animals; they are then adjusted to levels that will help protect humans. Sometimes 

these not-to-exceed levels differ among federal organizations because they used different exposure times 

(an 8-hour workday or a 24-hour day), different animal studies, or other factors. 

Recommendations and regulations are also updated periodically as more information becomes available. 

For the most current information, check with the federal agency or organization that provides it. 

Some regulations and recommendations for ethylene glycol include the following: 

Levels in drinking 

water set by EPA 

The EPA has determined that exposure to ethylene glycol in drinking water 

at concentrations of 20 milligrams per liter (mg/L) for 1 day or 6 mg/L for 

10 days is not expected to cause any adverse effects in a child. 

The EPA has determined that lifetime exposure to 14 mg/L ethylene glycol 

in drinking water is not expected to cause any adverse effects. 

For more information on the regulations and guidelines that apply to ethylene glycol, see Chapter 8. 

1.10 WHERE CAN I GET MORE INFORMATION? 

If you have any more questions or concerns, please contact your regional poison control center (1-800-

222-1222), community or state health or environmental quality department, or contact ATSDR at the 

address and phone number below. 

ATSDR can also tell you the location of occupational and environmental health clinics. These clinics 

specialize in recognizing, evaluating, and treating illnesses that result from exposure to hazardous 

substances. 

Toxicological profiles are also available on-line at www.atsdr.cdc.gov and on CD-ROM. You may 

request a copy of the ATSDR ToxProfilesTM CD-ROM by calling the toll-free information and technical 
 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 7 

1. PUBLIC HEALTH STATEMENT 

assistance number at 1-800-CDCINFO (1-800-232-4636), by e-mail at cdcinfo@cdc.gov, or by writing 

to: 

Agency for Toxic Substances and Disease Registry
 

Division of Toxicology and Environmental Medicine
 

1600 Clifton Road NE
 

Mailstop F-62
 

Atlanta, GA 30333
 

Fax: 1-770-488-4178
 

Organizations for-profit may request copies of final Toxicological Profiles from the following: 

National Technical Information Service (NTIS)
 

5285 Port Royal Road
 

Springfield, VA 22161
 

Phone: 1-800-553-6847 or 1-703-605-6000
 

Web site: http://www.ntis.gov/
 
 

ETHYLENE GLYCOL 8 

1. PUBLIC HEALTH STATEMENT 

This page is intentionally blank. 
 

 

 

 

 

 

ETHYLENE GLYCOL 9 

2. RELEVANCE TO PUBLIC HEALTH
 

2.1 BACKGROUND AND ENVIRONMENTAL EXPOSURES TO ETHYLENE GLYCOL IN 

THE UNITED STATES 

Ethylene glycol is a colorless, odorless liquid that mixes completely with water. It is released into the 

environment primarily through industrial emissions and through the use and disposal of ethylene glycolbased automobile antifreeze and airport de-icing formulations. Ethylene glycol that is released into the 

environment does not persist since it is degraded within days to a few weeks in air, water, and soil. 

Available monitoring data indicate that ethylene glycol is only found near areas of release. Ethylene 

glycol vapor concentrations measured in the air at airports during de-icing spray operations ranged from 

0.05 to 22 mg/m3

. Ethylene glycol has also been detected in airport stormwater. Background 

concentrations of ethylene glycol in the environment are not available. 

Since ethylene glycol is not expected to be present away from areas where it is released, background 

exposure of the general population to this substance is not expected to be important. The most common 

route of exposure to ethylene glycol for the general population is through dermal contact with ethylene 

glycol-containing automobile antifreeze. However, accidental or intentional ingestion of antifreeze is the 

most serious route of exposure, resulting in thousands of poisonings reported each year in the United 

States. Ethylene glycol concentrations in blood, urine, tissue, or breast milk are not available for the 

general population. 

Individuals who live near hazardous waste sites, industrial facilities where ethylene glycol is produced or 

used, or areas where ethylene glycol-based de-icing formulations are used may be exposed to ethylene 

glycol through dermal contact with contaminated soil or water, inhalation of ethylene glycol vapor or 

mist, or ingestion of contaminated groundwater. Occupational exposure through dermal contact and 

inhalation of ethylene glycol vapor or mist is expected for individuals involved in airport de-icing spray 

operations. Ethylene glycol has been detected in urine samples collected from airport de-icing workers. 

Ingestion of ethylene glycol containing antifreeze is a potential route of exposure for children since they 

are attracted to the bright colors of antifreeze formulations and the sweet taste of ethylene glycol. 

Exposure through ingestion is more likely to occur when adults leave opened antifreeze containers within 

reach or store antifreeze in other types of containers such as beverage bottles. A bittering agent has been 

added to some ethylene glycol antifreeze formulations in order to deter ingestion; however, caution 

should still be used since ingestion poisoning has occurred even when a bittering agent was present. 
 

 

 

 

 

 

ETHYLENE GLYCOL 10 

2. RELEVANCE TO PUBLIC HEALTH 

2.2 SUMMARY OF HEALTH EFFECTS 

Ethylene glycol is quickly and extensively absorbed through the gastrointestinal tract of many species, but 

dermal absorption is slow in rodents and is expected to be slow in humans. Limited information is 

available on absorption of inhaled ethylene glycol, but the existing toxicity studies suggest absorption via 

the respiratory tract by both humans and rodents. Following absorption, ethylene glycol is distributed in 

aqueous compartments throughout the body. Ethylene glycol is initially metabolized to glycolaldehyde 

by alcohol dehydrogenase (with possible contribution from cytochrome P-450 enzymes). Glycolaldehyde 

is rapidly converted to glycolate and glyoxal by aldehyde oxidase and aldehyde dehydrogenase. 

Metabolism of glycolate by glycolate oxidase or lactate dehydrogenase results in the formation of 

glyoxylate, which may be further metabolized to formate, oxalate, glycine, and carbon dioxide. 

Elimination of ethylene glycol occurs via exhaled carbon dioxide and urinary elimination of both ethylene 

glycol and glycolic acid. The half-life for elimination in humans has been estimated to be in the range of 

2.5–8.4 hours. 

The vast majority of information relating to the toxicity of ethylene glycol is from studies of oral 

exposure. Information on the health effects of oral exposure in humans is largely limited to case reports 

of acute accidental or intentional ingestion of ethylene glycol. These case reports have identified three 

stages of acute oral ethylene glycol toxicity in humans. These stages are well documented and occur 

within 72 hours after ingestion. The first stage involves central nervous system depression, metabolic 

changes (hyperosmolality), and gastrointestinal upset, and spans the period from 30 minutes to 12 hours. 

During the second stage (12–24 hours after ingestion), metabolic acidosis and associated cardiopulmonary symptoms (tachypnea, hyperpnea, tachycardia, cyanosis, pulmonary edema, and/or cardiac 

failure) become evident. During stage three, which covers the period 24–72 hours after ethylene glycol 

ingestion, renal involvement becomes evident. The third stage is characterized by flank pain and 

oliguria/anuria. Histopathological findings show renal tubular necrosis and deposition of calcium oxalate 

crystals. Often, the cardiopulmonary effects in the second stage are not evident, so the distinguishing 

symptoms of ethylene glycol intoxication are central nervous system depression, acidosis, and 

nephrotoxicity. Limited information suggests that a fourth stage involving cranial nerves may occur 6 or 

more days after exposure. This stage is characterized by neurological symptoms including deafness, 

facial paralysis, and other sequelae. 
 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 11 

2. RELEVANCE TO PUBLIC HEALTH 

Reports of fatalities following ingestion of ethylene glycol indicate that a volume of 150–1,500 mL 

consumed at one time may cause death. In humans, the lethal dose of ethylene glycol is estimated to be in 

the range of 1,400–1,600 mg/kg. Based on these estimates, it appears that humans may be more 

susceptible to the acute lethality of ingested ethylene glycol than other species. In laboratory animals 

(rats, mice, monkeys), oral doses of ≥4,000 mg/kg were needed to cause death. However, difficulties in 

quantifying the amounts consumed by persons who have succumbed to the toxic effects lead to 

uncertainty in the human lethal dose estimates. 

A study with human subjects found that inhalation exposure to ethylene glycol vapor at an average 

concentration of 30 mg/m3 for 20–22 hours/day for 30 days was well tolerated, with effects that were 

essentially limited to occasional complaints of mild upper respiratory tract irritation. There were no 

indications of renal or other systemic effects as shown by urinalysis, hematology and clinical chemistry 

evaluations, and neurobehavioral tests throughout the exposure period. Short-term, high-exposure 

sessions found that ethylene glycol was tolerated for only 15 minutes at 188 mg/m3

, 2 minutes at 

244 mg/m3

, and one or two breaths at 308 mg/m3. The study authors stated that respiratory tract irritation 

became common at an ethylene glycol concentration of approximately 140 mg/m3 (incidence data and 

exposure duration not specified) and that concentrations ≥200mg/m3 were intolerable due to strong 

irritation of the upper respiratory tract that included a burning sensation in the trachea and a burning 

cough. This study was used as the basis for an acute-duration inhalation MRL for ethylene glycol (see 

Section 2.3). 

Animal studies indicate that oral exposure to ethylene glycol can cause effects in a number of different 

organ systems, although the developing fetus and kidneys are particularly sensitive and well-documented 

targets of toxicity. Oral effects have also been observed in the central and peripheral nervous systems, 

heart, liver, hematopoietic system, and immunological and lymphoreticular systems. Available 

information suggests that the neurological and cardiopulmonary effects stem from metabolic acidosis 

associated with acute, high-dose exposures. Reported effects on the immunological and lymphoreticular 

systems are limited to suppressed immune responses in mice given a single near-lethal oral dose, and 

neutrophilia and lymph node hemosiderosis in rats orally exposed for 2 years. Effects on hematological 

parameters have largely been observed at high doses in longer-term studies, and are not consistently 

reported across studies or across species. 

Oral studies in animals have identified the developing fetus as the most sensitive target for acute-duration 

exposure to ethylene glycol. Gavage exposure of laboratory rodents to ethylene glycol during gestation 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 12 

2. RELEVANCE TO PUBLIC HEALTH 

results in a consistent pattern of developmental effects including reduced fetal body weight and increases 

in malformations, particularly axial skeletal malformations. Developmental toxicity has also been 

assessed by the inhalation and dermal routes. Results of the inhalation developmental studies are 

generally consistent with the oral findings, but are confounded by concurrent oral exposure via ingestion 

of aerosolized ethylene glycol on the fur of exposed animals. A single study of dermal exposure to 

ethylene glycol in pregnant mice did not indicate developmental effects. 

The kidney is clearly identified as the most sensitive target organ in rats and mice after intermediateduration oral exposure. Typical renal effects included oxalate crystal deposition and renal tubular 

dilation, vacuolation, and degeneration. Oxalate, a metabolite of glycolic acid, forms a precipitate in the 

presence of calcium, and the deposition of these crystals in the renal tubules are hallmarks of ethylene 

glycol toxicity. Glycolic acid accumulation and metabolic acidosis do not contribute to renal toxicity, 

which is solely caused by oxalate crystal accumulation. Males were more sensitive than females, and rats 

were more sensitive than mice. Chronic oral studies confirm that the kidney is a main target organ in 

male rats, although a minor liver effect (slight fatty metamorphosis) occurred in female rats at doses 

lower than those inducing kidney effects. No hepatic effects were observed in intermediate-duration 

studies. 

There is no indication that ethylene glycol is carcinogenic based on results of a limited renal cancer 

mortality study in chemical plant workers and well-designed chronic oral bioassays in rats (one study) 

and mice (two studies). 

A more detailed discussion of the developmental and renal effects associated with ethylene glycol 

exposure follows. The reader is referred to Section 3.2, Discussion of Health Effects by Route of 

Exposure, for additional information on these and other health effects. 

Developmental Effects. No studies have addressed the developmental toxicity of ethylene glycol in 

humans. The developmental toxicity of ethylene glycol in animals has been assessed by inhalation, oral, 

and dermal exposure in acute-duration studies and by oral exposure in intermediate-duration studies. The 

acute oral studies indicate that developmental effects (a skeletal variation and total malformations) occur 

at doses of ≥500 mg/kg/day when administered by gavage during gestation days (Gd) 6–15 to CD-1 mice. 

Dose-response data for these developmental effects in mice were used to derive an acute-duration oral 

MRL for ethylene glycol (see Section 2.3). Reduced fetal body weight occurred in mice given gavage 

doses of ≥750 mg/kg/day. In CD rats, doses of ≥1,000 mg/kg/day by gavage on Gd 6–15 have resulted in 
 

 

 

 

 

ETHYLENE GLYCOL 13 

2. RELEVANCE TO PUBLIC HEALTH 

increased incidences of skeletal malformations. In F344 rats dosed on Gd 6–15 with 1,000 mg/kg/day in 

feed, skeletal malformations were not observed, suggesting the possible importance of dose-rate in 

producing developmental effects; however, strain differences in response cannot be ruled out. No 

teratogenic effects were observed in rabbits exposed to maternally lethal oral doses of 2,000 mg/kg/day 

during gestation. In the only dermal exposure study, no developmental toxicity occurred in pregnant 

CD-1 mice that were treated with 6-hour daily exposures to ethylene glycol (estimated doses up to 

3,549 mg/kg/day) by occluded cutaneous application on Gd 6–15. 

Developmental toxicity studies of inhaled ethylene glycol in mice and rats found effects consistent with 

the oral findings, but all of the studies are confounded by concurrent ingestion of ethylene glycol 

deposited on the fur. In inhalation studies using whole-body exposure, significant effects on implant 

viability, weight of live fetuses, and incidence of external, visceral, and skeletal malformations were 

observed in mice exposed to ≥1,000 mg/m3 for 6 hours/day on Gd 6–15. In rats exposed similarly, 

reduced ossification at some sites in the axial skeleton occurred at ≥1,000mg/m3

, however, in an Expert 

Panel Review, the National Toxicology Program-Center for the Evaluation of Risks to Human 

Reproduction concluded that the relationship of this effect to treatment was uncertain due to the lack of a 

dose-response relationship. In a follow-up study aimed at reducing the confounding oral exposure, 

pregnant CD-1 mice were exposed nose-only to 500–2,500 mg/m3 aerosolized ethylene glycol. At 

2,500 mg/m3

, live fetal body weight was significantly reduced, and there was a significant increase in the 

one type of skeletal malformation (fused ribs). Increases in some skeletal variations were also observed 

at 2,500 mg/m3

, and one type (extra ossification sites in the sagittal suture) was significantly increased at 

≥500 mg/m3

. The authors observed that the animals in the nose-only experiment were also exposed by 

ingestion of ethylene glycol deposited on the face. Furthermore, one study noted that stress from restraint 

in the nose-only exposure study may have contributed to the developmental effects observed with 

ethylene glycol, which were similar in nature to effects observed in a study of restrained nose-only 

exposure to water vapor. Because of the confounding oral exposure in both the whole-body and noseonly experiments, a study concluded that the data from these studies were not suitable for evaluation of 

effect levels from inhalation exposure to ethylene glycol. 

Developmental effects of intermediate-duration oral exposure to ethylene glycol include kidney effects in 

offspring and decreased pup body weights. In mice tested in a continuous breeding assay, pup body 

weights were reduced in both F1 and F2 generations at drinking water doses of ≥897 mg/kg/day. In a 

15-day gestational exposure study (Gd 6–20), postnatal effects on kidney weights were observed in pups 

of CD rats exposed to gavage doses of ≥1,250 mg/kg/day in utero. In a three-generation study of rats, no 
 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 14 

2. RELEVANCE TO PUBLIC HEALTH 

effects on gestation survival or pup body weight through postpartum day (ppd) 21 were observed in F1 or 

F2 pups after parental exposure to dietary doses up to 1,000 mg/kg/day. 

Recent reviews of mechanistic studies on ethylene glycol developmental toxicity have concluded that 

glycolic acid, alone or in combination with its downstream metabolites and resultant metabolic acidosis, 

was likely the proximate toxicant responsible for the developmental effects of ethylene glycol. Using a 

physiologically based pharmacokinetic (PBPK) model developed for humans, a study estimated that the 

glycolic acid blood threshold concentration for developmental effects in rodents would only be reached in 

human females ingesting doses of 350 mg/kg (assuming a 58-kg female). While the model has been 

validated against data from acute human oral and inhalation exposures to ethylene glycol, the model was 

not calibrated to pregnancy, and it is not clear whether physiological and/or biochemical changes that 

could affect ethylene glycol toxicokinetics might occur during pregnancy. Further, a study noted that 

additional data were needed to fully delineate the rate of glycolic acid metabolism in humans; such 

additional data may alter the model predictions of peak glycolic acid concentrations in humans exposed to 

ethylene glycol. 

Renal Effects. The renal toxicity of ethylene glycol in humans is well documented in numerous case 

reports of accidental or intentional ingestion. Adverse renal effects occur in the third stage of human 

ethylene glycol poisoning, which occurs 24–72 hours after acute exposure. The hallmark of renal toxicity 

is the presence of calcium oxalate monohydrate crystals in the renal tubules and urine following ingestion 

of large amounts of ethylene glycol. Characteristic histopathological changes include renal tubular focal 

degeneration, atrophy, and interstitial inflammation. Renal damage, if untreated, can lead to renal failure. 

With therapy, normal or near-normal renal function can be restored. 

Humans who inhaled ethylene glycol showed no indications of impaired renal function. No significant 

alterations in renal end points were found in volunteers exposed to ethylene glycol aerosol at an average 

concentration of 30 mg/m3 for 20–22 hours/day for 30 days. Evaluations were performed throughout the 

study and included examination of urine for presence of oxalate crystals and erythrocytes; determinations 

of urine volume, specific gravity, color, clarity, pH, amino acid nitrogen, and creatinine; and 

determination of blood urea nitrogen. There also was no indication of renal impairment in aviation 

workers who were intermittently exposed to ethylene glycol during airplane de-icing operations over a 

2-month winter period. Ethylene glycol concentrations as high as 22 mg/m3 for vapor and 190 mg/m3 for 

mist were measured, although the vast majority of samples were below the limit of quantification 

(2.5 mg/m3 for vapor and 17 mg/m3 for mist); the frequency and average levels and durations of exposure 
 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 15 

2. RELEVANCE TO PUBLIC HEALTH 

were not reported. Measurements of urinary albumin, β-N-acetyl-glucosaminidase, β-2-microglobulin, 

and retinol-binding protein were used to assess kidney function. 

Renal effects in orally exposed animals are consistent with those observed in humans. In acute-duration 

studies, effects occurred in the kidneys of rats exposed to 1,250–2,500 mg/kg/day by gavage or 2,615– 

5,270 mg/kg/day in drinking water for 9–29 days, and rabbits exposed to 2,000 mg/kg/day by gavage for 

13 days. Evaluation of these animals showed effects that generally included increased kidney weight and 

renal tubular calcium oxalate deposits, dilation, degeneration, and/or necrosis. 

The renal effects of intermediate-duration oral exposure to ethylene glycol are well characterized in a 

number of studies in rats and mice. These studies indicate that renal toxicity varies with sex, species, and 

strain, with males more sensitive than females, rats more sensitive than mice, and Wistar rats more 

sensitive than other strains of rats. Renal effects in Sprague-Dawley rats that were exposed to ethylene 

glycol in drinking water for 90 days included renal tubular oxalate crystal deposition, dilation, and 

degeneration in males at ≥947 mg/kg/day and females at 3,087 mg/kg/day. Findings in F344 rats exposed 

for 13 weeks via diet included renal tubular dilation, necrosis, fibrosis, and oxalate crystal deposition in 

males at ≥2,500 mg/kg/day, and mild renal lesions (e.g., inflammation and vacuolation) with no crystal 

deposition in females at 10,000 mg/kg/day. Results of 16-week dietary studies showed that male Wistar 

rats are approximately twice as sensitive as male F344 rats to ethylene glycol nephrotoxicity, and that 

kidney lesions in male Wistar rats occurred at average doses as low as 180 mg/kg/day. In a 13-week 

dietary study in B6C3F1 mice, effects were observed in the kidneys (minimal to mild tubule dilation, 

cytoplasmic vacuolation, and regenerative hyperplasia, without tubular oxalate crystal deposition) of 

males at ≥6,450 mg/kg/day, with no renal effects in females at doses ≤16,000 mg/kg/day. 

Chronic toxicity studies provide information on renal effects in rats and mice exposed to ethylene glycol 

in the diet for up to 2 years. Males were more sensitive than females and rats were more sensitive than 

mice. Renal effects in rats included oxalate nephrosis in Wistar males at ≥300 mg/kg/day, oxalate crystal 

deposition and apparent tubular degenerative changes in Sprague-Dawley males at ≥375 mg/kg/day and 

females at ≥750 mg/kg/day, and oxalate nephrosis (and consequent mortality) in F344 males at 

1,000 mg/kg/day, with changes in F344 females at this dose limited to increased kidney weight and 

crystalluria without histopathology. No kidney histopathology occurred in male or female CD-1 mice 

exposed to 1,000 mg/kg/day or female B6C3F1 mice exposed to ≤12,000 mg/kg/day, and effects in male 

B6C3F1 mice were limited to small numbers of oxalate-like crystals and/or calculi in the renal tubules, 

urethrae, and urinary bladder in a few animals at 6,000 mg/kg/day. 
 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 16 

2. RELEVANCE TO PUBLIC HEALTH 

2.3 MINIMAL RISK LEVELS (MRLs) 

Estimates of exposure levels posing minimal risk to humans (MRLs) have been made for ethylene glycol. 

An MRL is defined as an estimate of daily human exposure to a substance that is likely to be without an 

appreciable risk of adverse effects (noncarcinogenic) over a specified duration of exposure. MRLs are 

derived when reliable and sufficient data exist to identify the target organ(s) of effect or the most sensitive 

health effect(s) for a specific duration within a given route of exposure. MRLs are based on 

noncancerous health effects only and do not consider carcinogenic effects. MRLs can be derived for 

acute, intermediate, and chronic duration exposures for inhalation and oral routes. Appropriate 

methodology does not exist to develop MRLs for dermal exposure. 

Although methods have been established to derive these levels (Barnes and Dourson 1988; EPA 1990), 

uncertainties are associated with these techniques. Furthermore, ATSDR acknowledges additional 

uncertainties inherent in the application of the procedures to derive less than lifetime MRLs. As an 

example, acute inhalation MRLs may not be protective for health effects that are delayed in development 

or are acquired following repeated acute insults, such as hypersensitivity reactions, asthma, or chronic 

bronchitis. As these kinds of health effects data become available and methods to assess levels of 

significant human exposure improve, these MRLs will be revised. 

Inhalation MRLs 

•	 An MRL of 2 mg/m3 has been derived for acute-duration inhalation exposure (14 days or less) to 

ethylene glycol. 

Information on the toxicity of acute-duration inhalation exposure to ethylene glycol is available from an 

experimental study in humans (Wills et al. 1974) and three developmental toxicity studies in rats and 

mice (Tyl 1988a; Tyl et al. 1995a, 1995b). 

In the human study, exposure to ethylene glycol aerosol at an average concentration of 23 mg/m3 for 20– 

22 hours/day for 14 days was well tolerated, with effects that were essentially limited to occasional 

complaints of mild upper respiratory tract irritation (Wills et al. 1974). There were no indications of renal 

or other systemic effects as shown by urinalysis and hematology, clinical chemistry, and neurobehavioral 

evaluations. Short-term, high-exposure sessions showed that respiratory tract irritation became common 

at approximately 140 mg/m3 and intolerable for more than a few minutes at approximately 200 mg/m3

. 
 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 17 

2. RELEVANCE TO PUBLIC HEALTH 

Developmental toxicity studies were conducted in rats and mice using whole-body exposure to 150, 

1,000, or 2,500 mg/m3 of ethylene glycol aerosol for 6 hours/day on Gd 6–15 (Tyl 1988a; Tyl et al. 

1995a). Reduced ossification at some sites in the axial skeleton occurred in rats at ≥1,000mg/m3

, 

although an Expert Panel Review (NTP-CERHR 2004) concluded that the relationship of this effect to 

treatment was uncertain due to the lack of a dose-response relationship. In mice, significant effects on 

implant viability, weight of live fetuses, and incidence of external, visceral, and skeletal malformations 

were observed at ≥1,000 mg/m3

. Maternal toxicity (e.g., increased liver weight in rats and reduced body 

weight gain in mice) was evident at 2,500 and 1,000 mg/m3 in rats and mice, respectively (Tyl et al. 

1995a). Both of these whole-body exposure studies were confounded by concurrent ingestion exposure to 

ethylene glycol deposited on the fur. In a follow-up study aimed at reducing concurrent exposure from 

ingestion, mice were exposed nose-only to 500, 1,000, or 2,500 mg/m3 aerosolized ethylene glycol for 

6 hours/day on Gd 6–15 (Tyl 1988a; Tyl et al. 1995b). In maternal animals, there were no effects other 

than changes in kidney weights. Absolute kidney weight was significantly increased at 1,000 and 

2,500 mg/mg3

, and relative kidney weight was increased at 2,500 mg/m3; however, the increases were 

small (6.6–9.5% higher than controls) and microscopic examination of kidneys showed no 

histopathological changes. At 2,500 mg/m3

, live fetal body weight was significantly reduced, and there 

was a significant increase in the one type of skeletal malformation (fused ribs). Increases in some skeletal 

variations were observed at 2,500 mg/m3

, and one type (extra ossification sites in the sagittal suture) was 

significantly increased at concentrations of ≥500mg/m3

. The authors observed that the animals in the 

nose-only experiment were also exposed by ingestion of ethylene glycol deposited on the face (Tyl 

1988a; Tyl et al. 1995a). Furthermore, stress from restraint in the nose-only exposure study may have 

contributed to the developmental effects observed with ethylene glycol (NTP-CERHR 2004; Tyl et al. 

1995a), which were similar in nature to effects observed in a study of restrained nose-only exposure to 

water vapor (Tyl et al. 1994). 

Because of the confounding oral exposures in both the whole-body and nose-only developmental toxicity 

studies, NTP-CERHR (2004) concluded that the data from these studies were not suitable for evaluation 

of effect levels from inhalation exposure to ethylene glycol. The available data do, however, provide a 

conservative estimate of the inhalation (NOAEL), with the caveat that total exposure to ethylene glycol in 

these studies included intake via ingestion. Collectively, these studies suggest that inhalation exposure to 

ethylene glycol at a nominal concentration of about 150 mg/m3 is not associated with developmental 

toxicity in mice or rats, or renal toxicity in mice (kidney histopathology not assessed in rats). The next 

highest concentration (500 mg/m3 in the nose-only study) was associated with developmental effects 
 

 

 

 

 

 

 

ETHYLENE GLYCOL 18 

2. RELEVANCE TO PUBLIC HEALTH 

(increased incidence of skeletal variations), but it is not possible to conclusively relate these effects to 

inhalation of ethylene glycol. 

As indicated above, the developmental studies (Tyl 1988a; Tyl et al. 1995a, 1995b) collectively suggest 

that 150 mg/m3 is a conservative NOAEL for developmental toxicity in rats and kidney toxicity in mice. 

This concentration is similar to the 140 mg/m3 lowest-observed-adverse-effect level (LOAEL) for 

respiratory tract irritation in humans (Wills et al. 1974). The human NOAEL of 23 mg/m3 is a suitable 

basis for MRL derivation because it is based on evaluations for renal and other systemic effects as well as 

local irritation, and is well within the NOAEL range for developmental toxicity in animals. As 

summarized below, the human study (Wills et al. 1974) was conducted in prisoners. ATSDR recognizes 

that there is some ethical concern about using a study in prisoners for MRL derivation, but the protocol 

was acceptable at the time the study was conducted. 

In the human study, health effects were assessed in 19 male prisoners who voluntarily were exposed to 

ethylene glycol aerosol for 20–22 hours/day for 30 days. The diameter of the aerosol droplets ranged 

from 1 to 5 μm. Air samples were collected at three intervals during each day from each of five sampling 

locations. The concentrations of ethylene glycol from the five sampling locations were averaged for each 

sampling time and means from the three sampling times were averaged to obtain a mean daily value. The 

daily means were averaged to obtain weekly and fortnightly means. The highest measured concentration 

of ethylene glycol during the first 14 days of the study was 44.8 mg/m3

. Mean weekly concentrations 

during the first 2 weeks of the study were 29 and 17 mg/m3

, respectively. The highest measured 

concentration of ethylene glycol during the 30-day study was 66.8 mg/m3

; mean weekly concentrations 

during the entire 30-day exposure period ranged from 17 to 49 mg/m3

. The study authors stated that 

mean daily ethylene glycol concentrations ranged from 3 to 67 mg/m3

, but did not provide more specific 

information regarding mean daily concentrations. The average mean weekly exposure was 23 mg/m3 for 

days 1–14 and 30 mg/m3 for days 1–30. The average exposure levels did not include brief periods during 

the last 10 days of the study in which the concentration was intentionally increased to higher levels to 

assess acute responses. A control group consisted of 14 male prisoners; 10 of these men were never 

exposed to ethylene glycol, whereas the remaining 4 men had been exposed to a mean concentration of 

37 mg/m3 for 20–22 hours/day for 7 days during the week that preceded the start of the study. Subjective 

responses (symptoms) were monitored throughout the study. During the last 10 days of the study, the 

concentration of ethylene glycol was occasionally intentionally increased to various high levels (up to 

308 mg/m3

) when the volunteers left the exposure chamber during meals; subjective responses to short 

exposures to the high concentrations were assessed when they re-entered the chamber. Complete physical 
 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 19 

2. RELEVANCE TO PUBLIC HEALTH 

examinations that included slit-lamp, electrocardiographic, and electroencephalographic studies, and a 

battery of psychological tests designed to reveal effects on simple reaction time, reaction time with 

discrimination, visual-motor coordination, depth perception, and mental ability (encoding and subtraction 

accuracy) were conducted on all subjects pre-exposure and after 14 and 30 days of exposure. Blood 

samples were collected on days 0, 1, 3, 5, 8, 12, 19, 22, 26, and 29 for evaluation of hematology, clinical 

chemistry (including blood urea nitrogen, serum creatinine, and liver enzymes), and ethylene glycol 

concentration. Urine was evaluated daily for oxalate crystals, erythrocytes, and ethylene glycol, and 

twice weekly for volume, specific gravity, color, clarity, pH, amino acid nitrogen, and creatinine. 

Concentrations of ethylene glycol in the blood and urine were similar in the exposed and control groups. 

The near-continuous exposure levels were tolerated with effects that were limited to occasional 

complaints of upper respiratory tract irritation, slight headache, and low backache (incidences and other 

information not reported). The short-term, high-exposure sessions showed that irritation became common 

at approximately 140 mg/m3 (incidences and exposure duration not specified); exposure was tolerated for 

only 15 minutes at 188 mg/m3

, 2 minutes at 244 mg/m3, and one or two breaths at 308 mg/m3. Based on 

these results and those of other trials, the investigators concluded that concentrations ≥200mg/m3 were 

intolerable due to strong irritation of the upper respiratory tract that included a burning sensation in the 

trachea and a burning cough. Because the near-continuous exposures were tolerated with respiratory 

irritation that was infrequent and not serious, and not accompanied by neurological, hematology, clinical 

chemistry, or urinalysis findings indicative of renal or other systemic effects, the interim (12–14-day) 

findings in this study identified a NOAEL of 23 mg/m3 for acute-duration exposure in humans. The 

LOAEL in humans was 140 mg/m3 because brief exposures to this concentration commonly caused 

respiratory irritation. 

The NOAEL of 23 mg/m3 for respiratory tract irritation and systemic toxicity in humans (Wills et al. 

1974) was divided by an uncertainty factor of 10 (for human variability) to derive an MRL of 2 mg/m3 for 

acute inhalation exposure to ethylene glycol. The NOAEL was not adjusted for discontinuous daily 

exposure (20 hours/24 hours) because the critical effect is concentration dependent and not duration 

dependent. 

An MRL has not been derived for intermediate-duration inhalation exposure (15–364 days) to ethylene 

glycol. 
 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 20 

2. RELEVANCE TO PUBLIC HEALTH 

Information on the toxicity of intermediate-duration inhalation exposure to ethylene glycol is available 

from two studies in humans (Gérin et al. 1997; Wills et al. 1974) and one multiple species study in 

animals (Coon et al. 1970). 

In one of the human studies, health effects were assessed in 19 male prisoners who voluntarily were 

exposed to ethylene glycol aerosol at an average concentration of 30 mg/m3 for 20–22 hours/day for 

30 days (Wills et al. 1974). The exposure was well tolerated, with effects that were essentially limited to 

occasional complaints of mild upper respiratory tract irritation; there were no indications of renal or other 

systemic effects as shown by urinalysis and hematology, clinical chemistry, and neurobehavioral 

evaluations. This study is summarized in detail in the acute inhalation MRL section. The other human 

study assessed kidney function in 33 male aviation workers who were intermittently exposed to ethylene 

glycol-based de-icing fluid during airplane de-icing operations during a 2-month winter period (Gérin et 

al. 1997). Personal exposures to ethylene glycol ranged up to 22 mg/m3 for vapor and 190 mg/m3 for 

mist, although the vast majority of samples were below the limits of quantification (2.5 mg/m3 for vapor 

and 17 mg/m3 for mist). The frequency and average levels and durations of exposure were not reported. 

Measurements of urinary albumin, β-N-acetyl-glucosaminidase, β-2-microglobulin, and retinol-binding 

protein indicated no impairment of renal function. 

In the animal study, Sprague-Dawley and Long-Evans rats (15/concentration, mixed strains and sexes), 

Princeton-derived guinea pigs (15/concentration, mixed sexes), New Zealand rabbits (3 males/ 

concentration), Beagle dogs (2 males/concentration), and Squirrel monkeys (2–3 males/concentration) 

were exposed to apparently aerosolized ethylene glycol in concentrations of 0, 10, or 57 mg/m3 for 

8 hours/day, 5 days/week for 6 weeks, or to 0 or 12 mg/m3 continuously for 90 days (Coon et al. 1970). 

Evaluations included clinical signs, limited hematology, serum liver enzymes, gross pathology, and 

limited histology (mainly kidney, liver, spleen, heart, and lung). No clear treatment-related effects were 

observed in the intermittent exposure 6-week study. In the 90-day study, continuous exposure to 

12 mg/m3 caused moderate to severe eye irritation in 3/3 rabbits and corneal opacity with possible 

blindness in 2/15 rats, and mortality in 1/3 rabbits, 1/15 rats, and 3/15 guinea pigs. 

The experimental study in humans (Wills et al. 1974) identified a NOAEL of 30 mg/m3 for respiratory 

tract irritation and systemic effects for near-continuous exposure to ethylene glycol for 30 days. 

Urinalysis in this study showed no indications of renal effects (e.g., presence of oxalate crystals in urine), 

and are consistent with the negative results of kidney function evaluations in the aviation workers who 

were intermittently exposed to lower levels of ethylene glycol for 2 months (Gérin et al. 1997). The 
 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 21 

2. RELEVANCE TO PUBLIC HEALTH 

6-week intermittent exposure study in rats, guinea pigs, and small numbers of rabbits, dogs, and monkeys 

(Coon et al. 1970) identified a NOAEL of 57 mg/m3 for kidney histopathology and other systemic effects 

in all species. Continuous exposure to 12 mg/m3 for 90 days caused ocular irritation in rats and rabbits 

(Coon et al. 1970), but confidence in this LOAEL is low due to small numbers of affected animals, and its 

relevance is unclear because there was no eye irritation in the humans near-continuously exposed to 

30 mg/m3 for 30 days (Wills et al. 1974). Continuous exposure to 12 mg/m3 for 90 days also caused 

mortality in rats, rabbits, and guinea pigs, although the reliability of this LOAEL is low due to low 

incidences, small numbers of animals, and likely confounding by oral exposure from ingestion of aerosol 

deposited on the fur. Documentation for this probable confounder is provided by the developmental 

toxicity studies (Tyl et al. 1995a, 1995b) discussed in the acute-duration inhalation MRL derivation. The 

human NOAEL of 30 mg/m3 is not a suitable basis for intermediate-duration MRL derivation due to 

insufficient information on renal and other possible systemic effects of exposures >30 days. Although 

exposures as long as 90 days were conducted in the animal study, it was limited in scope (e.g., lacked 

sufficient numbers of animals and urinalysis) and likely confounded by oral exposure. 

An MRL has not been derived for chronic-duration inhalation exposure (365 days or more) to ethylene 

glycol. 

Information on the health effects of chronic exposure to ethylene glycol is essentially limited to the 

negative results of an epidemiologic study on renal cancer mortality in humans (Bond et al. 1985). This 

study does not provide a basis for MRL consideration because it lacks noncancer end points, measured 

exposure concentrations, and other relevant information. 

Oral MRLs 

•	 An MRL of 0.8 mg/kg/day has been derived for acute-duration oral exposure (14 days or less) to 

ethylene glycol. 

Information on effects of acute-duration oral exposure to ethylene glycol is available from human case 

reports, a 10-day drinking water study in rats (Robinson et al. 1990), a 4-day gavage study examining 

effects on hematology and reproductive organs (Hong et al. 1988), and developmental toxicity studies in 

mice, rats, and rabbits (Maronpot et al. 1983; Marr et al. 1992; Neeper-Bradley et al. 1995, Price et al. 

1985; Schuler et al. 1984; Tyl 1989; Tyl et al. 1993). 
 

 

 

 

ETHYLENE GLYCOL 22 

2. RELEVANCE TO PUBLIC HEALTH 

The available human studies consist of clinical case reports of high-dose intentional or accidental 

ingestion of ethylene glycol, and are thus not suitable for dose-response assessment. 

In the 10-day drinking water study, groups of 10 male and 10 female Sprague-Dawley rats were 

administered 0, 0.5, 1.0, 2.0, or 4.0% ethylene glycol; reported mean compound consumption was 649, 

1,343, 2,615, and 5,279 mg/kg/day in males, and 794, 1,506, 2,953, and 7,327 mg/kg/day in females 

(Robinson et al. 1990). The incidence and severity of renal lesions were significantly increased and doserelated in males at doses ≥2,615 mg/kg/day; effects included tubular dilation, degeneration, necrosis, and 

intratubular calcium oxalate crystals. Effects on body weight, organ weights, and hematological 

parameters were observed at the high dose only. Changes in serum chemistry parameters were observed 

at lower doses in both males and females; however, these were not accompanied by histopathological 

changes in the liver. This study identified a LOAEL of 2,615 mg/kg/day for renal toxicity in male 

Sprague-Dawley rats. 

No effects were observed on hematology parameters, but dose-related effects on bone marrow and 

erythropoiesis were noted when doses of 0, 50, 100, or 250 mg/kg/day ethylene glycol were given for 

4 consecutive days by gavage to B6C3F1 mice (Hong et al. 1988). Seven mice per sex were sacrificed 

1 day postexposure for measurement of body, liver, thymus, spleen, kidney, and testis weights, and 

histopathology of these organs as well as the lung, heart, adrenals, stomach, bone marrow, urinary 

bladder, intestines, and uterus. Hematology, bone marrow parameters, and erythropoiesis were evaluated 

in other groups of mice examined between 1 and 14 days after exposure. Microscopic examination of the 

spleen and bone marrow did not reveal any histopathological changes, and there were no significant 

changes to hematological parameters (hemoglobin, hematocrit, mean corpuscular volume, erythrocyte, 

and leukocyte counts) evaluated 5 days after exposure termination. Exposure to ethylene glycol resulted 

in statistically significant decreases in bone marrow cellularity (up to about 25% below control values) at 

doses ≥100 mg/kg/day; this effect persisted up to 14 days after exposure in males. Granulocytemacrophage progenitor formation was suppressed (~15% below controls) at 50 mg/kg/day in males 

evaluated 14 days postexposure and at higher doses in both males and females evaluated at earlier time 

points. The magnitude of reduction in granulocyte-macrophage progenitor formation ranged up to 40% 

below controls at 250 mg/kg/day. Iron uptake in the bone marrow was suppressed (38% below controls) 

in males at 250 mg/kg/day. 

While Hong et al. (1988) observed bone marrow effects in male mice exposed to doses of 50– 

250 mg/kg/day, the biological significance of these effects is uncertain. No effects were observed on any 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 23 

2. RELEVANCE TO PUBLIC HEALTH 

hematological parameters, or on bone marrow or spleen histology (Hong et al. 1988). Studies using much 

higher doses and longer durations have failed to indicate effects on bone marrow, spleen, or hematology 

in mice, and provided inconsistent findings in rats. No histological changes in the bone marrow were 

observed in mice or rats exposed to higher doses of ethylene glycol for longer durations; these included 

B6C3F1 mice receiving ≤16,000 mg/kg/day from the diet for 13 weeks or ≤12,000 mg/kg/day from the

diet for 2 years (Melnick 1984; NTP 1993), F344 rats receiving ≤10,000 mg/kg/day from the diet for

13 weeks (Melnick 1984), and Sprague-Dawley rats receiving ≤7,327 mg/kg/day from the drinking water

for 10 or 90 days (Robinson et al. 1990). Results of routine hematology evaluations in these studies were 

unremarkable except for some alterations in the 10- and 90-day studies in rats. In the 10-day study, 

statistically significant decreases in hemoglobin, hematocrit, erythrocytes, and total leukocytes (7.3, 8.9, 

8.5, and 34.8% less than controls, respectively) occurred in female rats at 7,327 mg/kg/day (Robinson et 

al. 1990). In the 90-day study, total leukocyte counts were significantly reduced in female rats at 597, 

3,087, and 5,744 mg/kg/day (32, 30, and 50% less than controls, respectively) (Robinson et al. 1990). 

Results of differential counts were not reported and no clear hematological changes occurred in male rats 

in either study. Hematology evaluations were also negative in other studies that did not examine bone 

marrow histology; these included studies of B6C3F1 mice receiving ≤12,000 mg/kg/day fromthe diet for 

2 years (DePass 1986a), Wistar rats administered ≤2,000 mg/kg/day by gavage for 4 weeks (Schladt et al. 

1998), and Wistar rats receiving ≤1,128 mg/kg/day from the diet for 16 weeks (Gaunt et al. 1974). In 

male F344 rats receiving 1,000 mg/kg/day from the diet for 2 years, significant hematological changes 

were observed, but this dose also caused mortality due to renal toxicity (DePass 1986a). 

The hematopoietic system is an established target system for several ethylene glycol ethers (e.g., ethylene 

glycol monomethyl ether, ethylene glycol monobutyl ether [IRIS 2010]). For these compounds, 

hematological effects are consistently observed across different species, doses, and exposure durations. 

In contrast, few studies have suggested hematological effects from ethylene glycol exposure, and those 

with positive findings were at higher doses than Hong et al. (1988) and gave inconsistent results. Given 

the lack of supporting evidence for hematological, bone marrow, or splenic effects in mice and rats 

exposed to much higher doses of ethylene glycol and for longer durations, the biological significance of 

the effects observed by Hong et al. (1988) is considered uncertain, and the results of this study do not 

provide an adequate basis from which to derive an acute-duration oral MRL for ethylene glycol. 

The remaining animal studies collectively identify the developing fetus as the most sensitive target of 

acute oral exposure to ethylene glycol. In acute-duration oral developmental toxicity studies in rodents, 

fetal effects have consistently been observed at doses that are not maternally toxic. Furthermore, the 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 24 

2. RELEVANCE TO PUBLIC HEALTH 

developmental effects observed after ethylene glycol exposure appear to be generally consistent across 

studies and across rodent species, with the primary end point consisting of skeletal malformations. The 

incidence of malformations was increased in CD-1 mice at doses ≥500 mg/kg/day when administered by 

gavage during gestation (Gd 6–15) (Neeper-Bradley et al. 1995; Tyl 1989). Embryotoxicity was also 

manifested as a reduction in fetal body weight in CD-1 mice given doses ≥750 mg/kg/day on Gd 6– 

15 (Neeper-Bradley 1990; Price et al. 1985; Tyl 1989). In rats, doses ≥1,000mg/kg/day by gavage on Gd 

6–15 resulted in an increased incidence of skeletal malformations in offspring (Neeper-Bradley 1990; 

Neeper-Bradley et al. 1995; Price et al. 1985). Decreases in pup body weight and increases in both the 

number of litters with malformations and the number of malformed fetuses per litter were observed in rats 

treated during Gd 6–15 with doses≥2,500 mg/kg/day (Neeper-Bradley 1990; Neeper-Bradley et al. 1995; 

Price et al. 1985). In mice given 3,000 mg/kg/day during Gd 6–15, neural tube and craniofacial defects 

were increased and the number of live fetuses per litter was decreased (Price et al. 1985). In contrast to 

the results in rodents, no developmental effects were observed in fetuses of rabbits gavaged at a 

maternally lethal dose level of 2,000 mg/kg/day during gestation (Tyl et al. 1993). 

Among the available developmental studies, only four (Price et al. 1985 [rat study only]; NTP 1988 [rats]; 

and Neeper-Bradley et al. 1995 or Tyl 1989 [mice and rats]) identified both a NOAEL and a LOAEL; the 

remaining studies identified only a NOAEL (Maronpot et al. 1983; Schuler et al. 1984; Tyl 1993) or a 

LOAEL (Price et al. 1985 [mice]; Marr 1992). The lowest LOAEL values were identified by NeeperBradley (1990; Neeper-Bradley et al. 1995; Tyl 1989) for mice (500 mg/kg/day) and rats 

(1,000 mg/kg/day) and by Price et al. (1985) for mice (750 mg/kg/day). Price et al. (1985) failed to 

identify a NOAEL for mice, while Neeper-Bradley et al. (1995; Tyl 1989) used lower doses and were 

able to identify both a NOAEL and a LOAEL; thus, the data from Price et al. (1985) were not considered 

for acute-duration oral MRL derivation. Both the mouse and rat studies published by Neeper-Bradley 

(1990; Neeper-Bradley et al. 1995; Tyl 1989) were well-conducted studies using adequate numbers of 

animals (25–30/dose), including four dose levels in addition to controls, and evaluating relevant end 

points (skeletal and other malformations as well as reproductive and litter parameters). The mouse study 

(Neeper-Bradley et al. 1995; Tyl 1989) identified the lowest LOAEL (500 mg/kg/day) for developmental 

effects following gavage administration of ethylene glycol to pregnant dams during critical stages of 

organogenesis; thus these data were selected for use in deriving the acute-duration oral MRL for ethylene 

glycol. 

In the mouse study by Neeper-Bradley et al. (1995; Tyl 1989), groups of 30 timed-pregnant CD-1 mice 

were given doses of 50, 150, 500, or 1,500 mg/kg ethylene glycol daily by gavage on Gd 6–15; vehicle 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 25 

2. RELEVANCE TO PUBLIC HEALTH 

controls were given water on the same schedule. Maternal animals were observed daily for clinical signs 

and weighed periodically; water intake was measured throughout gestation. At sacrifice on Gd 18, body 

weight, gravid uterine weight, liver weight, and kidney weight were measured in dams. Kidneys from 

control and high-dose dams were examined microscopically. Corpora lutea and uterine contents were 

evaluated, and live fetuses were weighed and sexed. External, visceral, and skeletal malformations and 

variations in the fetuses were evaluated. 

No effects on maternal body weight, water consumption, or liver or kidney weight were observed. There 

were no significant effects on the number of corpora lutea/dam, number of total, nonviable, or viable 

implants/litter, or sex ratio. Average fetal body weight per litter was reduced (13% below controls) at 

1,500 mg/kg/day. The incidence of individual external or visceral malformations was not significantly 

increased in any treatment group relative to the vehicle control; however, exencephaly (a malformation 

observed by Price et al. [1985] at higher doses) was observed in two fetuses in the 500 mg/kg/day group 

and in three fetuses of the 1,500 mg/kg/day dose group. There was a significant increase in the incidence 

of two skeletal malformations (fused ribs or thoracic arches) in the 1,500 mg/kg/day group (15/21 litters 

with fused ribs vs. 1/19 controls; 8/21 litters with fused thoracic arches vs. 0/19 controls). Further, the 

incidence of total malformations per litter (external, visceral, and skeletal) was significantly increased 

both at 500 and 1,500 mg/kg/day (3/19, 7/20, 5/24, 12/24, and 17/21 from control to high dose). The 

incidences of 23 skeletal variations were increased in the 1,500 mg/kg/day group. One of these variations 

(bilateral extra rib 14) was also significantly increased at ≥500mg/kg/day (4/19, 4/20, 6/24, 17/24, and 

21/21 in control through high-dose groups, respectively). This study identified a developmental NOAEL 

of 150 mg/kg/day and a LOAEL of 500 mg/kg/day for increased incidence of total malformations and 

bilateral extra rib 14. The high dose (1,500 mg/kg/day) was a NOAEL for maternal effects. 

To derive a point of departure for MRL derivation, benchmark dose (BMD) modeling was conducted 

using the mouse data on the incidence of litters with malformations (of any kind) and on the incidence of 

one skeletal variation (bilateral extra rib 14). These two end points were observed at lower doses than 

other observed effects (skeletal malformations, pup body weight reductions). All dichotomous models in 

the EPA Benchmark Dose Software (Version 2.1.1) were fit to the malformation and skeletal variation 

data. Although one of the end points modeled (total malformations) represents a more serious effect, the 

group sizes in this study (19–24 litters/dose examined) did not support a benchmark response (BMR) 

lower than 10%; thus, an extra risk incidence of 10% above controls was selected as the BMR. The 

multistage and quantal linear models converged on the same model providing the best fit to the data on 

total malformations; these models both predicted a BMD10 of 113.84 mg/kg/day and a BMDL10 of 
 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 26 

2. RELEVANCE TO PUBLIC HEALTH 

75.59 mg/kg/day. For the data on bilateral extra rib 14, the probit model provided the best fit, and 

predicted a BMD10 of 99.35 mg/kg/day and a BMDL10 of 75.56 mg/kg/day. Modeling of both the 

malformation and skeletal variation end points resulted in the same BMDL10, indicating that an acute oral 

MRL based on this point of departure should provide protection against both effects. The BMDL10 of 

76 mg/kg/day was divided by an uncertainty factor of 100 (10 for extrapolation from animals to humans 

and 10 for human variability) to derive an MRL of 0.8 mg/kg/day for acute-duration oral exposure to 

ethylene glycol. 

Although some mechanistic information suggests that humans may be less sensitive than rodents to the 

developmental effects of ethylene glycol, the available data are not adequate to support a lower 

interspecies uncertainty factor; thus, a full 10-fold uncertainty factor was used for interspecies 

extrapolation. While in vitro data suggest that humans metabolize glycolic acid (the proximate 

developmental toxicant) more efficiently than rats (Booth et al. 2004; Corley et al. 2005), NTP-CERHR 

(2004) observed that the data supporting the glycolic acid metabolic rate in humans are limited. In 

addition, NTP-CERHR (2004) reviewed preliminary data indicating that the inverted yolk sac placenta, a 

stage in placental development that does not exist in humans, tends to concentrate weak acids such as 

glycolic acid in the embryonic fluids. These data suggest enhanced sensitivity to ethylene glycol 

developmental effects in rodents compared with humans; however, NTP-CERHR (2004) characterized 

the available data as inconclusive. A 10-fold uncertainty factor for human variability was also used. 

Ethylene glycol metabolism is known to involve alcohol dehydrogenase and aldehyde dehydrogenase, 

and may also involve cytochrome p450 isozymes (NTP-CERHR 2004). Polymorphisms in the genes 

encoding these enzymes may lead to wide variability in the production and elimination of glycolic acid 

and other metabolites in humans exposed to ethylene glycol, but data quantifying the range of variability 

are not currently available (NTP-CERHR 2004). In addition, fetal and/or placental differences in 

expression of these enzymes over the course of gestation will affect local concentrations of glycolic acid 

and other metabolites to which the developing conceptus is exposed, yet little is known about these 

differences (NTP-CERHR 2004). 

Corley et al. (2005) published a PBPK model to predict the behavior of ethylene glycol and glycolic acid 

in rats and humans. However, there are no in vivo data from which the saturation concentration of 

glycolic acid (the proximate developmental toxicant of ethylene glycol) could be determined in humans. 

Furthermore, no model has yet been developed for mice, the species used in the study selected for MRL 

derivation. As a result, available data do not support the use of PBPK modeling to derive an acute oral 

MRL for ethylene glycol based on developmental toxicity in mice. 
 

 

 

 

 

 

ETHYLENE GLYCOL 27 

2. RELEVANCE TO PUBLIC HEALTH 

A key consideration in the acute-duration oral database for ethylene glycol stems from the use of gavage 

administration in most of the developmental toxicity studies. Bolus doses from gavage administration 

lead to higher peak concentrations of glycolic acid (the proximate developmental toxicant) in the blood 

than occur with equivalent doses at slower dose-rates associated with environmentally-relevant exposures 

(Carney et al. 2001; NTP-CERHR 2004). This indicates that results of high-dose and high dose-rate 

gavage studies lead to exaggerated risk estimates. In support of this notion, Maronpot et al (1983) 

observed neither fetal nor maternal toxicity following dietary exposure of pregnant F344 rat dams to 

ethylene glycol during Gd 6–15 at concentrations resulting in doses as high as 1,000 mg/kg/day, while 

Neeper-Bradley et al. (1995) reported skeletal malformations and effects on fetal body weight in CD rats 

given 1,000 mg/kg via gavage. Data supporting glycolic acid as the proximate toxicant (Carney et al. 

1996, 1999; Klug et al. 2001; Munley et al. 1999), and evidence for much lower serum levels of glycolic 

acid following slower dose-rate administration of ethylene glycol than the fast dose-rate resulting from 

bolus dosing (Carney et al. 2001, 2002), suggest that the lack of developmental toxicity observed by 

Maronpot et al. (1983) likely resulted from the difference in dose-rate. However, strain differences in 

susceptibility to ethylene glycol cannot be ruled out as an explanation for the dissimilar results. NeeperBradley et al. (1995) also reported significantly increased incidences of skeletal variations and 

malformations in fetuses of CD-1 mice administered ethylene glycol by gavage at doses ≥500 mg/kg/day

(compared to controls) but not at doses ≤150 mg/kg/day. Lamb et al (1985) used the same strain of mice 

(CD-1 strain) in a continuous breeding study in which groups of mice were exposed to ethylene glycol in 

the drinking water at concentrations of 0, 0.25, 0.5, or 1% (estimated doses of 0, 410, 840, or 

1,640 mg/kg/day) for the entire study period which began in the F0 females prior to mating and continued 

to weaning of the final F1 generation produced during 14 weeks of 1:1 cohabitation with a male. Unusual 

facial features (shorter snout, wide-set eyes) were observed in some of the high-dose F1 offspring and 

further skeletal examination with Alizarin Red in 4 mice/sex/group revealed a pattern of skeletal defects 

that included shortened skull bones, fused ribs, abnormally shaped or missing sternebrae, and abnormal 

vertebrae. None of these defects were observed in examined control mice. Although the study authors 

stated that neither the low- nor mid-dose groups were significantly affected, it appears that this statement 

refers to gross observations, not the more detailed skeletal examinations performed on high-dose 

offspring. Thus, the study of Lamb et al. (1985) did not identify a definitive NOAEL, and a direct 

comparison between the effects of high dose-rate (bolus gavage) and slower dose-rate (drinking water 

consumption) within the same strain of mice cannot be made. 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 28 

2. RELEVANCE TO PUBLIC HEALTH 

Slikker et al. (2004) developed a working model to describe the mode of action for ethylene glycol 

developmental toxicity based on available results of pharmacokinetic, developmental toxicity, and 

mechanistic data. According to the model, a threshold of approximately 2 mM of glycolic acid in 

maternal blood (approximately 4 mM in the conceptus) is indicated, below which developmental effects 

are not elicited. Apparent requirements for exceeding this threshold include (1) a high dose of ethylene 

glycol, (2) an exposure route that results in rapid absorption as occurs following oral exposure, and 

(3) administration at a rapid rate as occurs under bolus gavage dosing. 

The potential impact of pregnancy on the pharmacokinetics of ethylene glycol in rats was assessed in a 

study by Pottenger et al. (2001). Pregnant and nonpregnant CD rats were administered 13C-labeled 

ethylene glycol via gavage on Gd 10 at doses of 10 or 2,500 mg/kg. Blood concentration time courses 

and urinary data for the pregnant and nonpregnant rats were similar, indicating that ethylene glycol 

pharmacokinetics were not significantly altered at least by Gd 10 exposure. Based on this result, the 

extensive body of pharmacokinetic data for nonpregnant laboratory animals appears to be relevant for the 

period of pregnancy as well. Some degree of uncertainty is inherent, however, because this study 

assessed pregnancy-related pharmacokinetics at a single time point in the gestation period. 

Available mechanistic data indicate that humans may be less sensitive than rodents to the developmental 

effects of ethylene glycol. Limited in vitro data indicate that humans metabolize glycolic acid (the 

proximate developmental toxicant) more efficiently than rats (Booth et al. 2004; Corley et al. 2005). As 

noted by NTP-CERHR (2004) and Slikker et al. (2004), preliminary data indicate that the conceptus of 

rats and mice concentrates glycolic acid due to pH gradients between maternal blood and the conceptus, 

the conceptus being more alkaline. Conversely, pH gradients between maternal blood and the conceptus 

of rabbits are the reverse, favoring diffusion of weak acids such as glycolic acid out of the conceptus. 

This species-specific difference in pH gradient may explain why the rabbit is relatively insensitive to the 

developmental effects of ethylene glycol. Although quantitative data are not available regarding the 

distribution of glycolic acid in the human conceptus, the human conceptus shares some common 

morphological features with the rabbit conceptus (e.g., yolk sac morphology, large volume of 

extraembryonic fluid relative to embryo size) that might favor reduced exposure of the human conceptus 

to glycolic acid. 

In summary, based on evidence that mice are more sensitive than rats to ethylene glycol developmental 

toxicity; the lack of comparative data to demonstrate the effect of dose rate on developmental end points 

in a common species and strain of laboratory animal; the lack of in vivo quantitative metabolic data in 
 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 29 

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humans; and the lack of a PBPK model for mice, the results of the gavage study of Neeper-Bradley et al. 

(1995) are considered to be potentially relevant to humans. 

•	 An MRL of 0.8 mg/kg/day has been adopted for intermediate-duration oral exposure (15–
 

364 days) to ethylene glycol.
 

Information on the toxicity of intermediate-duration oral exposure to ethylene glycol essentially consists 

of several well-designed studies in rats (Cruzan et al. 2004; Gaunt et al. 1974; Melnick 1984; Robinson et 

al. 1990) and mice (Melnick 1984; NTP 1993). Based on generally comprehensive evaluations that 

included body and organ weights, food and water consumption, hematology, blood chemistry, urinalysis, 

and histopathology in adequate numbers of animals, these studies consistently showed that the kidney is 

the predominant and most sensitive target of ethylene glycol toxicity. As summarized below, renal 

toxicity varied with sex, species, and strain, with males more sensitive than females, rats more sensitive 

than mice, and Wistar rats more sensitive than other strains of rats. 

Renal effects in Sprague-Dawley rats that were exposed to ethylene glycol in drinking water for 90 days 

included renal tubular oxalate crystal deposition, dilation, and degeneration in males at ≥947 mg/kg/day 

and females at 3,087 mg/kg/day (Robinson et al. 1990). Key findings in F344 rats exposed for 13 weeks 

via diet consisted of renal tubular dilation, necrosis, fibrosis, and oxalate crystal deposition in males at 

≥2,500 mg/kg/day, mortality in males at 5,000 mg/kg/day, and mild renal lesions (e.g., inflammation and 

vacuolation) with no crystal deposition or mortality in females at 10,000 mg/kg/day (Melnick 1984). 

Results of 16-week dietary studies showed that male Wistar rats are approximately twice as sensitive as 

male F344 rats to ethylene glycol nephrotoxicity (Cruzan et al. 2004), and that kidney lesions in male 

Wistar rats occurred at average doses as low as 180 mg/kg/day (Gaunt et al. 1974). In a 13-week dietary 

study in B6C3F1 mice, effects were observed in the kidneys (minimal to mild tubule dilation, cytoplasmic 

vacuolation, and regenerative hyperplasia, without tubular oxalate crystal deposition) and liver 

(centrilobular hyaline degeneration) of males at ≥6,450mg/kg/day, with no effects in females at doses 

≤16,000 mg/kg/day (Melnick 1984; NTP 1993). 

The 16-week study by Cruzan et al. (2004) compared the renal toxicity of ethylene glycol in male Wistar 

and F344 rats. The comparison was conducted to confirm an apparent greater sensitivity of the Wistar 

strain indicated by seemingly inconsistent renal effect levels in key intermediate- and chronic-duration 

studies (i.e., a LOAEL of 180 mg/kg/day in Wistar rats exposed for 16 weeks [Gaunt et al. 1974] that was 

lower than a NOAEL of 200 mg/kg/day in F344 rats exposed for 2 years [DePass et al. 1986a]). In the 

Cruzan et al. (2004) study, groups of 10 male Wistar rats and 10 male F-344 rats were administered 
 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 30 

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ethylene glycol in the diet in constant dose levels of 0, 50, 150, 500, or 1,000 mg/kg/day for 16 weeks. 

Clinical signs, body weight, and food intake were evaluated throughout the study. Water consumption 

was measured and urine was collected for urinalysis during the 24 hours prior to sacrifice; parameters 

included specific gravity, pH, color, appearance, protein, glucose, bilirubin, urobilinogen, ketones, occult 

blood, leukocytes, nitrites, volume, and microscopy of sediment. Following sacrifice, complete 

necropsies were performed, and kidneys were evaluated for organ weight and histological changes and 

presence of alpha 2-μ-globulin. Effects observed in Wistar rats included reduced body weight gain at 

500 and 1,000 mg/kg/day (final weight 9 and 23% lower than controls), and reduced food intake and 

2/10 deaths at 1,000 mg/kg/day; these end points were not affected in F344 rats. Significantly increased 

water intake (~200% higher than controls) and urine volume, decreased urine specific gravity, and 

increased occurrence of white blood cells in urine occurred in Wistar rats at ≥500 mg/kg/day and 

F344 rats at 1,000 mg/kg/day. Calcium oxalate crystals in the urine were increased in both strains of rats 

at ≥150 mg/kg/day; incidences at 0, 50, 150, 500, and 1,000 mg/kg/day were 0/10, 1/10, 5/10, 10/10, and 

4/8 in Wistar rats, and 1/10, 0/10, 3/10, 10/10, and 7/10 in F344 rats. Absolute and relative kidney 

weights were significantly increased at ≥500 mg/kg/day in Wistar rats and 1,000 mg/kg/day in F344 rats. 

No treatment-related increases in alpha 2-μ-globulin were observed in either strain of rats. The 

histological examinations showed crystal deposition in the kidneys and associated nephropathy in both 

strains of rats at ≥500 mg/kg/day, with greater severity in the Wistar rats. Respective incidences of 

nephropathy with crystal deposition at 0, 50, 150, 500, and 1,000 mg/kg/day were 0/10, 0/10, 0/10, 10/10, 

and 10/10 in Wistar rats, and 0/10, 0/10, 0/10, 1/10, and 10/10 in F344 rats. Because crystal-induced 

nephropathy occurred in only 1/10 F344 rats at 500 mg/kg/day (compared to 10/10 Wistar rats at this 

dose), and six additional F344 rats at 500 mg/kg/day had crystals in the kidney tubules without 

nephropathy, this dose is a less serious LOAEL in the F344 rats. The severity of the crystal nephropathy 

in the Wistar rats at 500 mg/kg/day was approximately equivalent to that in the F344 rats at 

1,000 mg/kg/day. Due to the higher incidence and greater severity of the crystal nephropathy, as well as 

the accompanying impairment of kidney function (i.e., compromised kidney water regulation as indicated 

by increased urine volume and decreased urine specific gravity leading to increased water consumption), 

500 mg/kg/day is a serious LOAEL in the Wistar rats. The only effect observed at doses lower than 

500 mg/kg/day was calcium oxalate crystals in the urine of both strains at 150 mg/kg; this is a NOAEL 

because excretion of crystals in the urine reflects a detoxification process and is not considered adverse in 

the absence of crystal deposition in the renal tubule epithelium and associated histopathology. 

The 16-week study by Gaunt et al. (1974) exposed male and female weanling Wistar rats to diets 

containing 0, 0.05, 0.1, 0.25, or 1.0% ethylene glycol for 2 weeks (5/sex/dose), 6 weeks (5/sex/dose), or 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 31 

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16 weeks (15/sex/dose). Reported calculated average daily chemical intakes were 35, 71, 180, and 

715 mg/kg/day in males, and 0, 38, 85, 185, and 1,128 mg/kg/day in females. Intakes were averaged 

among rats housed five per cage and decreased throughout the study because the amount of ethylene 

glycol in the diet was not adjusted for changing food consumption and body weight. Survival, clinical 

signs, food and water intake, and body weight were evaluated throughout the exposure period. 

Hematology (hemoglobin, hematocrit, packed cell volume, total erythrocytes, reticulocytes, total and 

differential leukocytes), serum chemistry (urea, glucose, protein, albumin, glutamic-oxaloacetic 

transaminase, glutamic-pyruvic transaminase, and lactic dehydrogenase), organ weights (including 

kidneys, liver, spleen, brain, heart, stomach, small intestines, caecum, adrenals, pituitary, thyroid, and 

gonads), and histology (organs that were weighed and 19 additional tissues) were evaluated at the 2-, 6-, 

and 16-week sacrifices. Urinalysis (glucose, ketones, bile salts, blood, protein, and presence of oxalic 

acid crystals, cells, and other microscopic constituents) and renal function (urine concentration and 

dilution tests measuring volume and specific gravity, and cell excretion) were evaluated at weeks 2 and 

16. Urine was additionally analyzed for oxalic acid at weeks 2, 6, 12, 14, and 16. There were no clear 

exposure-related effects on survival, clinical signs, body weight, hematology, or serum chemistry. 

Pneumonial changes occurred in the lungs of most males and females and salivary adenitis occurred in 

90% of the males and 45% of the females, but these effects were not considered exposure-related. 

Urinary excretion of oxalic acid was significantly increased in males at 715 mg/kg/day at weeks 2–16 and 

in females at 1,128 mg/kg/day at weeks 6–16, with the magnitude of the effect markedly greater in males 

(100–500% of control levels) than females (40–100% of control values). Increased absolute kidney 

weight, oxalic acid crystals in urine, and excretion of a larger volume of urine with a lower specific 

gravity after a prolonged period (16 hours) without water were observed in the 715 mg/kg/day males at 

week 16. Exposure-related histopathologic changes occurred only in the kidneys. Incidences of kidney 

lesions were statistically significantly increased in males at ≥180mg/kg/day. Specific renal 

histopathologic findings in the males at 16 weeks included individual nephrons with degenerative changes 

(incidences of 0/15, 1/15, 1/15, 2/15, and 5/15 [p<0.05] in the control to high-dose groups), individual 

nephrons with degenerative changes and occasional oxalate crystals (0/15, 0/15, 0/15, 1/15, and 

4/15 [p<0.05]), and generalized tubular damage and heavy oxalate crystals (0/15, 0/15, 0/15, 0/15, and 

4/15 [p<0.05]). At 0, 35, 71, 180, and 715 mg/kg/day, the total incidence of male rats with oxalate 

crystals was 0/15, 0/15, 0/15, 1/15, and 10/15 (p<0.001), and the total incidence of male rats with renal 

tubular damage was 0/15, 1/15, 1/15, 4/15 (p<0.05), and 15/15 (p<0.001). Females had an increased 

incidence of renal tubular damage at 1,128 mg/kg/day, but the increase was not statistically significant. 

The histological evaluations of the kidneys in the five rats/sex/dose exposed for 2 or 6 weeks showed no 

statistically significant increases in incidences of specific changes, although the total incidence of animals 
 

 

ETHYLENE GLYCOL 32 

2. RELEVANCE TO PUBLIC HEALTH 

with tubular damage was significantly increased in the 715 mg/kg/day males at 6 weeks. Based on the 

16-week kidney histopathology data in male Wistar rats, this study identified a NOAEL of 71 mg/kg/day 

and a LOAEL of 180 mg/kg/day for intermediate-duration exposure. 

The 16-week studies of Cruzan et al. (2004) and Gaunt et al. (1974) provide dose-response data for the 

critical effect in the most sensitive species, strain, and sex (i.e., kidney lesions in male Wistar rats). The 

respective NOAEL and LOAEL values were 150 and 500 mg/kg/day in the Cruzan et al. (2004) study and 

71 and 180 mg/kg/day in the Gaunt et al. (1974) study. Although Gaunt et al. (1974) identified a lower 

apparent LOAEL, this study is not suitable for MRL consideration because the animal care was 

questionable and the daily dose was not constant. Nearly all of the rats, possibly from the beginning of 

the study, showed evidence of respiratory infection (pneumonia) and infectious salivary adenitis, either of 

which could have confounded the results. Also, the rats were fed a constant dietary percentage of 

ethylene glycol, such that daily consumption varied throughout the study. For example, in the 

180 mg/kg/day LOAEL group, the rats were exposed to approximately 300 mg/kg/day for the first 

2-weeks, which is a level above the threshold for renal toxicity in male Wistar rats in a 12-month study 

(Corley et al. 2008) (see chronic-duration MRL discussion). Further, the rats were housed in groups of 

five, such that consumption of individual rats among the groups likely varied. Hence, the dose levels in 

the Gaunt et al. (1974) study are not reliably consistent, unlike the study by Cruzan et al. (2004), which 

was conducted in the same rat strain and sex for the same duration. An additional reason to use the 

Cruzan et al. (2004) study for MRL derivation is that the 12-month study (Corley et al. 2008) showed the 

same NOAEL of 150 mg/kg/day and a LOAEL of 300 mg/kg/day, thus appearing to substantiate the 

results of Cruzan et al. (2004) but not Gaunt et al. (1974). 

The Cruzan et al. (2004) 16-week study in rats is a suitable basis for intermediate-duration oral MRL 

derivation because it identified the lowest reliable LOAEL and has no confounding factors. The 

incidences of the critical effect, crystal nephropathy, were 0/10, 0/10, 0/10, 10/10, and 10/10 at 0, 50, 150, 

500, and 1,000 mg/kg/day, respectively. This data set is not appropriate for BMD analysis because the 

incidences increased from 0% at doses ≤150 mg/kg/day to 100% at doses ≥500 mg/kg/day; the lack of 

low-response data points limits the accuracy of dose-response modeling. Selection of the NOAEL of 

150 mg/kg/day as a point of departure and application of an uncertainty factor of 100 (10 for animal to 

human extrapolation and 10 for human variability) yield an intermediate-duration oral MRL of 

1.5 mg/kg/day, but this value is higher than the acute-duration oral MRL of 0.8 mg/kg/day. Therefore, 

the acute-duration oral MRL was adoptedfor intermediate-duration oral exposure. The acute-duration 

oral MRL was derived from a study that identified a NOAEL of 150 mg/kg/day for developmental 
 

ETHYLENE GLYCOL 33 

2. RELEVANCE TO PUBLIC HEALTH 

toxicity in mice (Neeper-Bradley et al. 1995; Tyl 1989), which is the same as the intermediate- and 

chronic-duration NOAELs for kidney effects in male Wistar rats (Corley et al. 2008; Cruzan et al. 2004). 

Because available evidence indicates that the acute-duration oral MRL for ethylene should be protective 

for kidney effects following longer-term exposure, the acute-duration value of 0.8 mg/kg/day is adopted 

for intermediate-duration exposure. 

An MRL has not been derived for chronic-duration oral exposure (365 days or more) to ethylene glycol. 

The chronic oral toxicity of ethylene glycol has been evaluated in three studies in rats (Blood 1965; 

Corley et al. 2008; DePass et al. 1986a) and two studies in mice (DePass et al. 1986a; NTP 1993) using 

dietary exposure. As summarized below, the main target organs were the kidneys in rats and liver in 

mice, and rats were more sensitive than mice. 

Male Wistar rats (20/dose) were exposed to ethylene glycol in dietary doses of 0, 50, 150, 300 or 

400 mg/kg/day for 12 months (Corley et al. 2008). Ten rats/group (main group) were used to assess 

toxicity; end points included clinical observations, body weight, feed and water consumption, urinalysis, 

organ weights, gross necropsy, and kidney and bladder histopathology. Urinalysis was performed the 

week prior to study termination and included color, appearance, specific gravity, volume, pH, bilirubin, 

glucose, proteins, ketones, blood, urobilinogen, and microscopic evaluation for crystal types. Five 

rats/group were used to determine renal clearance of 14C-oxalate and 3

H-inulin, and five rats/group were 

used to evaluate concentrations of ethylene glycol and its glycolate and oxalate metabolites in blood, 

urine, and kidneys. No adverse effects occurred at 50 or 150 mg/kg/day, but toxicity was pronounced at 

300 and 400 mg/kg/day. Effects at 400 mg/kg/day included mortality (4/10 died or were moribund on 

days 43–193) and weight loss, which led to early termination of the remaining animals on day 203. 

Mortality was also increased at 300 mg/kg/day (4/10 died or were moribund on days 111–221). Other 

effects at ≥300 mg/kg/day included increased water consumption with corresponding increased urine 

volume and decreased urine specific gravity, increased absolute and relative kidney weights, and gross 

and histopathological changes in the kidneys and bladder. Gross pathology included calculi, dilatation, 

and hemorrhage in the bladder at ≥300 mg/kg/day and calculi and dilatation in the renal pelvis and ureter 

at 400 mg/kg/day. Renal histopathology occurred in the majority of animals at 300 mg/kg/day and in all 

animals at 400 mg/kg/day; lesions included crystalluria-related nephropathy, tubule dilatation, 

birefringent crystals (particularly in the pelvic fornix), pelvic dilatation, and transitional cell hyperplasia. 

Incidences of crystal nephropathy, the most prevalent lesion, were 0/14, 0/15, 0/15, 12/13, and 10/10 at 0, 

50, 150, 300, and 400 mg/kg/day, respectively. Histopathological changes in the bladder occurred in the 

majority of animals at ≥300 mg/kg/day; the basic change was transitional cell hyperplasia, progressing to 
 

 

ETHYLENE GLYCOL 34 

2. RELEVANCE TO PUBLIC HEALTH 

acute inflammation and hemorrhage in severe cases. The early deaths were considered related to the 

inflammation and hemorrhage of the bladder wall. Decreased urinary pH and increased urinary oxalate 

crystals occurred at all treatment levels (≥50 mg/kg/day); these effects were not considered adverse, but 

rather normal metabolic/physiological consequences of ethylene glycol exposure. There were no 

treatment-related effects on renal clearance of oxalate or inulin. Urinary levels of oxalate were 

unchanged at all doses, urinary ethylene glycol followed a linear dose-response relationship, and urinary 

glycolic acid was linear between 50 and 150 mg/kg/day with a disproportionate nonlinear increase at 

300 mg/kg/day. Kidney concentrations of glycolate and oxalate were unchanged at 50 and 

150 mg/kg/day, but clear nonlinear increases in both of these metabolites occurred at ≥300 mg/kg/day, 

indicating that the accumulation of calcium oxalate in the kidneys correlated with the appearance of renal 

toxicity. A NOAEL of 150 mg/kg/day and a LOAEL of 300 mg/kg/day were identified in male Wistar 

rats based on histopathology in the kidneys (crystal nephropathy) and bladder (inflammation and 

hemorrhage). 

Sprague-Dawley rats (16/sex/dose) were fed ethylene glycol in estimated dietary doses of 0, 75, 150, 375, 

750, or 3,000 mg/kg/day for up to 2 years (Blood 1965). Evaluations included food and water 

consumption, body and organ weights, hematology, urinary protein, and limited histopathology. 

Decreased body weight gain, increased water consumption, proteinuria, and mortality occurred in males 

at ≥750 mg/kg/day and females at 3,000 mg/kg/day. Incidences of calcification (oxalate crystal 

deposition) in the kidneys were increased in both sexes at ≥750 mg/kg/day, and oxalate-containing calculi 

were increased in males at ≥750 mg/kg/day and females at 3,000 mg/kg/day. Oxalate crystal deposition 

also occurred in males at 375 mg/kg/day (4/10 compared to 0/7 controls), although the increase was not 

statistically significantly. The report implied, but did not adequately document, that many of the animals 

with crystal deposition in the renal tubules also had degenerative changes in the tubular epithelium. Due 

to the insufficiently reported histopathology findings and lack of a clear (statistically significant) increase 

in oxalate crystal deposition at 375 mg/kg/day due to small number of animals, this study provides limited 

evidence that 375 mg/kg/day was a LOAEL for kidney toxicity in male Sprague-Dawley rats; the 

NOAEL was 150 mg/kg/day. 

F344 rats (130/sex/dose) were fed ethylene glycol in approximate dietary doses of 0, 40, 200, or 

1,000 mg/kg/day for up to 2 years (DePass et al. 1986a). End points included food and water 

consumption, body and organ weights, hematology, clinical chemistry, extensive urinalysis, and 

comprehensive histopathology. No treatment-related or statistically significant changes occurred in the 

male rats at 40 or 200 mg/kg/day. Toxicity was pronounced in males at 1,000 mg/kg/day as shown by 
 

 

ETHYLENE GLYCOL 35 

2. RELEVANCE TO PUBLIC HEALTH 

increased mortality from month 9 (100% day 475), and various other effects that included increased water 

consumption and urine volume, increased blood urea nitrogen (BUN) and serum creatinine, decreased 

urine specific gravity and pH, increased urinary calcium oxalate crystals, and increased kidney weight and 

lesions. All 1,000 mg/kg/day males sacrificed at 12 months had calcium oxalate crystalluria and multiple 

severe renal lesions that included tubular dilation, proteinosis, hyperplasia, glomerular shrinkage, and/or 

chronic interstitial nephritis. Most of the 1,000 mg/kg/day males that died during the study or were 

sacrificed when moribund had oxalate nephrosis, which was the primary cause of death, as well as 

hydronephrosis. In the male rats at 0, 40, 200, and 1,000 mg/kg/day, the total incidences of oxalate 

nephrosis were 0/256, 0/129, 0/129, and 95/116, respectively. Non-neoplasic lesions in several non-renal 

tissues were also significantly increased in the 1,000 mg/kg/day males; these included cellular hyperplasia 

in the parathyroids and mineralization in the heart (vessels and muscle), lungs (interstitial), stomach, and 

vascular system. A NOAEL of 200 mg/kg/day and a serious LOAEL of 1,000 mg/kg/day were identified 

in male F344 rats based on kidney toxicity (oxalate nephrosis)-induced mortality. 

In the female F344 rats, effects occurred in kidneys and lymph nodes at 1,000 mg/kg/day and liver at 

≥200 mg/kg/day (DePass et al. 1986a). Renal effects in females were limited to increased kidney weight 

and calcium oxalate crystals and uric acid crystals in the urine at 1,000 mg/kg/day; no kidney 

histopathology or mortality occurred as in males (DePass et al. 1986a). Hemosiderosis in the mesenteric 

lymph nodes was increased at 1,000 mg/kg/day. Hepatic effects included increases in mononuclear cell 

infiltrates at 1,000 mg/kg/day and fatty metamorphosis (slight) at ≥200 mg/kg/day. Total incidences of 

liver fatty metamorphosis in the 0, 40, 200, and 1,000 mg/kg/day females were 34/256, 16/129, 27/125, 

and 35/128, respectively; the increases at 200 and 1,000 mg/kg/day were statistically significant. The 

liver fatty metamorphosis is not considered to be adverse because the effect was slight and there was no 

other evidence of hepatotoxicity; at no time (6, 12, 18, or 24 months) was there an increase in liver 

function parameters (serum chemistry) or in liver weight, even in animals dosed at 1,000 mg/kg/day. 

Additionally, this was the only long-term study (intermediate- or chronic-duration) to find liver lesions in 

rats, and the mode of action supports the kidney as the critical target. Based on the kidney effects, a 

NOAEL of 200 mg/kg/day and a LOAEL of 1,000 mg/kg/day were identified in female F344 rats. 

CD-1 mice (80/sex/dose) were fed ethylene glycol in approximate dietary doses of 0, 40, 200, or 

1,000 mg/kg/day for up to 2 years (DePass et al. 1986a). Evaluations were limited to clinical signs, body 

weight, food consumption, and comprehensive histopathology. No clear treatment-related effects were 

observed in either sex, indicating that this study identified a NOAEL of 1,000 mg/kg/day and no LOAEL 

in CD-1 mice. In the other mouse study, B6C3F1 mice (60/sex/dose) were exposed to ethylene glycol in 
 

ETHYLENE GLYCOL 36 

2. RELEVANCE TO PUBLIC HEALTH 

the diet for up to 2 years (NTP 1993). Estimated average doses were 0, 1,500, 3,000, and 

6,000 mg/kg/day in males and 0, 3,000, 6,000, and 12,000 mg/kg/day in females. Evaluations included 

hematology, clinical chemistry, organ weights (limited), and comprehensive histopathology. Effects were 

essentially limited to increased incidences of hepatocellular hyaline degeneration in males at 

≥3,000 mg/kg/day and females at 12,000 mg/kg/day, and medial hyperplasia of the pulmonary arterioles 

in females at ≥3,000 mg/kg/day; the biological significance of the pulmonary lesion was unclear (NTP 

1993). Small numbers of oxalate-like crystals and/or calculi were noted in the renal tubules, urethrae, and 

urinary bladder in a few males at 6,000 mg/kg/day. A NOAEL of 1,500 mg/kg/day and a LOAEL of 

3,000 mg/kg/day for liver histopathology were identified in male B6C3F1 mice. 

Key findings in the chronic toxicity studies were kidney lesions (oxalate nephrosis) and mortality at 

≥300 mg/kg/day in male Wistar rats (Corley et al. 2008), kidney lesions (oxalate crystal deposition and 

implied degenerative changes) at ≥375 mg/kg/day and mortality at 750 mg/kg/day in male SpragueDawley rats (Blood 1965), kidney lesions (oxalate nephrosis) and mortality at 1,000 mg/kg/day in male 

F344 rats (DePass et al. 1986a), no kidney or liver histopathology in male or female CD-1 mice at 

1,000 mg/kg/day (DePass et al. 1986a), and liver lesions (hepatocellular hyaline degeneration) in male 

B6C3F1 mice at ≥3,000 mg/kg/day (NTP 1993). The kidney lesions and mortality in male rats occurred 

at doses that were NOAELs in mice, indicating that rats were more sensitive than mice and the most 

appropriate species for MRL consideration. 

Chronic effect levels for kidney lesions and mortality in male rats included a NOAEL of 150 mg/kg/day 

and a serious LOAEL of 300 mg/kg/day in Wistar males (Corley et al. 2008), a NOAEL of 

200 mg/kg/day and a serious LOAEL of 1,000 mg/kg/day in F344 males (DePass et al. 1986a), and a 

NOAEL of 150 mg/kg/day and a serious LOAEL of 750 mg/kg/day in Sprague-Dawley males (Blood 

1965). An apparent increase in kidney lesions without mortality occurred in Sprague-Dawley males at 

375 mg/kg/day (Blood 1965), suggesting that this dose was a less serious LOAEL for renal effects in this 

strain of rats. The 150 mg/kg/day NOAEL for renal effects in Wistar males (Corley et al. 2008) and 

Sprague-Dawley males (Blood 1965) is consistent with the 200 mg/kg/day NOAEL for renal effects in 

F344 males (DePass et al. 1986a). 

The study in male Wistar rats (Corley et al. 2008) is the most appropriate basis for chronic MRL 

derivation because it identified the lowest LOAEL (300 mg/kg/day) and is the only study providing 

information on effects of chronic exposure in Wistar rats, a strain shown to be approximately twice as 

sensitive as F344 rats to kidney toxicity in a 16-week study (Cruzan et al. 2004) (see intermediate-
 

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2. RELEVANCE TO PUBLIC HEALTH 

duration MRL discussion). The incidences of the critical chronic effect, oxalate nephropathy, were 0/14, 

0/15, 0/15, 12/13, and 10/10 at 0, 50, 150, 300, and 400 mg/kg/day, respectively (Corley et al. 2008). 

This data set is not appropriate for BMD analysis because the incidences increased from 0% in the rats at 

doses ≤150 mg/kg/day to 92% at 300 mg/kg/day and 100% at 400 mg/kg/day; the lack of low-response 

data points limits the accuracy of dose-response modeling. Selection of the NOAEL of 150 mg/kg/day 

and application of an uncertainty factor of 100 (10 for animal to human extrapolation and 10 for human 

variability) yield an MRL of 1.5 mg/kg/day, but this value is higher than the acute-duration oral MRL of 

0.8 mg/kg/day. It is against ATSDR policy to derive a chronic-duration MRL that is higher than the 

acute-duration MRL. The acute MRL is based on a NOAEL of 150 mg/kg/day for developmental toxicity 

in mice (Neeper-Bradley et al. 1995; Tyl 1989), which is the same as the intermediate- and chronicduration NOAELs for kidney effects in male Wistar rats (Corley et al. 2008; Cruzan et al. 2004). The 

available evidence therefore indicates that the acute-duration oral MRL should be protective for chronic 

kidney effects. 
 

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3.1 INTRODUCTION 

The primary purpose of this chapter is to provide public health officials, physicians, toxicologists, and 

other interested individuals and groups with an overall perspective on the toxicology of ethylene glycol. 

It contains descriptions and evaluations of toxicological studies and epidemiological investigations and 

provides conclusions, where possible, on the relevance of toxicity and toxicokinetic data to public health. 

A glossary and list of acronyms, abbreviations, and symbols can be found at the end of this profile. 

The general population may be exposed to ethylene glycol. Ethylene glycol is widely sold in grocery 

stores and in automobile supply, discount, drug, and other stores throughout the United States for general 

use as an antifreeze/coolant in automobile radiators. Additionally, it is used in the manufacturing or 

blending of polyester products; aircraft and runway de-icing fluids; heat transfer fluids used in heating, 

ventilation, and air conditioning systems; humectants; polyester and alkyd resins; plasticizers; electrolytic 

capacitors; low freeze dynamite; and brake and shock solutions. 

Dermal exposure, through activities such as changing antifreeze, is the most likely route of exposure to 

ethylene glycol, but dermal exposure is not likely to lead to toxic effects. Only oral exposure, through 

accidental or intentional ingestion, is likely to lead to such effects, and then only if a sufficient amount is 

swallowed at one time. A review of the literature for ethylene glycol indicated that the stages of oral 

ethylene glycol poisoning in humans are well understood and documented. There is adequate knowledge 

of ethylene glycol metabolism to permit successful treatment of ethylene glycol intoxication, and 

substantial information concerning pathology and pathophysiology of the organ systems involved is 

available. Although the majority of the studies in humans represent descriptions of case studies of 

accidental or intentional poisoning, or exposure in industrial settings, they have been collected for a 

period of >60 years. Animal studies corroborate human findings and were used to provide quantitative 

data to support observations made in humans. 

3.2 DISCUSSION OF HEALTH EFFECTS BY ROUTE OF EXPOSURE 

To help public health professionals and others address the needs of persons living or working near 

hazardous waste sites, the information in this section is organized first by route of exposure (inhalation, 

oral, and dermal) and then by health effect (death, systemic, immunological, neurological, reproductive, 
 

 

 

 

 

ETHYLENE GLYCOL 40 

3. HEALTH EFFECTS 

developmental, genotoxic, and carcinogenic effects). These data are discussed in terms of three exposure 

periods: acute (14 days or less), intermediate (15–364 days), and chronic (365 days or more). 

Levels of significant exposure for each route and duration are presented in tables and illustrated in 

figures. The points in the figures showing no-observed-adverse-effect levels (NOAELs) or lowestobserved-adverse-effect levels (LOAELs) reflect the actual doses (levels of exposure) used in the studies. 

LOAELs have been classified into "less serious" or "serious" effects. "Serious" effects are those that 

evoke failure in a biological system and can lead to morbidity or mortality (e.g., acute respiratory distress 

or death). "Less serious" effects are those that are not expected to cause significant dysfunction or death, 

or those whose significance to the organism is not entirely clear. ATSDR acknowledges that a 

considerable amount of judgment may be required in establishing whether an end point should be 

classified as a NOAEL, "less serious" LOAEL, or "serious" LOAEL, and that in some cases, there will be 

insufficient data to decide whether the effect is indicative of significant dysfunction. However, the 

Agency has established guidelines and policies that are used to classify these end points. ATSDR 

believes that there is sufficient merit in this approach to warrant an attempt at distinguishing between 

"less serious" and "serious" effects. The distinction between "less serious" effects and "serious" effects is 

considered to be important because it helps the users of the profiles to identify levels of exposure at which 

major health effects start to appear. LOAELs or NOAELs should also help in determining whether or not 

the effects vary with dose and/or duration, and place into perspective the possible significance of these 

effects to human health. 

The significance of the exposure levels shown in the Levels of Significant Exposure (LSE) tables and 

figures may differ depending on the user's perspective. Public health officials and others concerned with 

appropriate actions to take at hazardous waste sites may want information on levels of exposure 

associated with more subtle effects in humans or animals (LOAELs) or exposure levels below which no 

adverse effects (NOAELs) have been observed. Estimates of levels posing minimal risk to humans 

(Minimal Risk Levels or MRLs) may be of interest to health professionals and citizens alike. 

A User's Guide has been provided at the end of this profile (see Appendix B). This guide should aid in 

the interpretation of the tables and figures for Levels of Significant Exposure and the MRLs. 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 41 

3. HEALTH EFFECTS 

3.2.1 Inhalation Exposure 

Information regarding health effects of ethylene glycol following inhalation exposure is limited. Health 

effects in humans were found in only a few studies (Bond et al. 1985; Troisi 1950; Wills et al. 1974). 

Animal studies were described by Tyl (1985, 1988a). 

3.2.1.1 Death 

No studies were located regarding death in humans after inhalation exposure to ethylene glycol. 

Mortality occurred in 1/15 rats, 3/15 guinea pigs, 1/3 rabbits, 0/3 dogs, and 0/3 monkeys that were 

continuously whole-body exposed to 12 mg/m3

of ethylene glycol aerosol for 90 days, although none of 

the affected animals showed “any specific signs of toxicity” (Coon et al. 1970). This concentration is not 

a reliable LOAEL for mortality because intake of ethylene glycol from ingestion of aerosol deposited on 

the fur likely significantly contributed to total dose (Tyl et al. 1995a, 1995b). Exposure to 10 or 

57 mg/m3 ethylene glycol aerosol for 8 hours/day, 5 days/week for 6 weeks caused no mortality in rats 

(15/concentration), guinea pigs (15/concentration), rabbits (3/concentration), dogs (2/concentration), or 

monkeys (2/concentration) (Coon et al. 1970). 

3.2.1.2 Systemic Effects 

No studies were located regarding gastrointestinal, musculoskeletal, endocrine, dermal, ocular, body 

weight, or metabolic effects in humans or respiratory, gastrointestinal, musculoskeletal, dermal, or body 

weight effects in animals after inhalation exposure to ethylene glycol. The highest NOAEL values and all 

reliable LOAEL values for systemic effects in each species and duration category for ethylene glycol after 

inhalation exposure are reported in Table 3-1 and plotted in Figure 3-1. 

Respiratory Effects. Tolerable nose and throat irritation were occasional complaints in 19 volunteers 

(incidence and frequency not reported) who were exposed to ethylene glycol aerosol for 20–22 hours/day 

for 30 days in a controlled study (Wills et al. 1974). The average mean weekly exposure concentration 

was 23 mg/m3 for days 1–14 and 30 mg/m3 for days 1–30. Sessions in which the concentration was 

increased for short periods during the last 10 days of the study showed that upper respiratory tract 

irritation became common at approximately 140 mg/m3

, and caused exposure to be tolerated for only 

15 minutes at 188 mg/m3

, 2 minutes at 244 mg/m3, and one or two breaths at 308 mg/m3 due to symptoms 
336

140 188

N131

23232323

335

23

337

30303030

338

30

Table 3-1 Levels of Significant Exposure to Ethylene Glycol - Inhalation 

Exposure/ 

Duration/ 

a 

Key to Species Frequency 

Figure (Strain) (Route) 

ACUTE EXPOSURE Systemic 

1 Human 15 min 2 Human 14 d 

20-22 hr/d 

Neurological 

3 Human 14 d 

20-22 hr/d 

INTERMEDIATE EXPOSURE Systemic 

4 Human 30 d 

20-22 hr/d 

Neurological 

5 Human 30 d 

20-22 hr/d 

System 

Resp Resp Hemato Hepatic Renal Resp Hemato Hepatic Renal 

LOAEL 

NOAEL 

(mg/m3) 

Less Serious 

(mg/m3) 

Serious 

(mg/m3) 

Reference Chemical Form 

140 M (respiratory tract 

irritation) 

188 M (intolerable respiratory 

tract irritation) 

Wills et al. 1974 

b

23 M Wills et al. 1974 

23 M 23 M 23 M 

23 M Wills et al. 1974 30 M Wills et al. 1974 

30 M 30 M 30 M 

30 M Wills et al. 1974 

a The number corresponds to entries in Figure 3-1.b Used to derive an acute-duration inhalation minimal risk level (MRL) of 2 mg/m3; the NOAEL of 23 mg/m3 was divided by an uncertainty factor of 10 for human vad = day(s); Gastro = gastrointestinal; Gd = gestational day; Hemato = hematological; hr = hour(s); LOAEL = lowest-observed-adverse-effect level; M = male; min = = no-observed-adverse-effect level; Resp = respiratory
Respiratory 

Hematological Hepatic Renal Neurological 

Figure 3-1 Levels of Significant Exposure to Ethylene Glycol - Inhalation 

Acute (≤14 days) 

Systemic 

mg/m3
	

1000
	

1
	

1
	

100
	

2
	 2
	 2
	 2
	 3
	

10
	

1
	

ETHYLENE GLYCOL

3. HEALTH EFFECTS

c-Cat 

d-Dog

r-Rat 

p-Pig

q-Cow

 -Humans 

k-Monkey

m-Mouse 

h-Rabbit 

a-Sheep 

f-Ferret 

j-Pigeon

e-Gerbil 

s-Hamster 

g-Guinea Pig 

n-Mink 

o-Other

 Cancer Effect Level-Animals

 LOAEL, More Serious-Animals

LOAEL, Less Serious-Animals

NOAEL - Animals

 Cancer Effect Level-Humans

 LOAEL, More Serious-Humans

LOAEL, Less Serious-Humans

NOAEL - Humans

 LD50/LC50

Minimal Risk Level

 for effects

 other than

 Cancer 

43
Respiratory 

Hematological Hepatic Renal Neurological 

Figure 3-1 Levels of Significant Exposure to Ethylene Glycol - Inhalation (Continued)

Intermediate (15-364 days) 

Systemic 

mg/m3
	

100
	

4
	 4
	 4
	 4
	 5
	

10
	

ETHYLENE GLYCOL

3. HEALTH EFFECTS

c-Cat 

d-Dog

r-Rat 

p-Pig

q-Cow

 -Humans 

k-Monkey

m-Mouse 

h-Rabbit 

a-Sheep 

f-Ferret 

j-Pigeon

e-Gerbil 

s-Hamster 

g-Guinea Pig 

n-Mink 

o-Other

 Cancer Effect Level-Animals

 LOAEL, More Serious-Animals

LOAEL, Less Serious-Animals

NOAEL - Animals

 Cancer Effect Level-Humans

 LOAEL, More Serious-Humans

LOAEL, Less Serious-Humans

NOAEL - Humans

 LD50/LC50

Minimal Risk Level

 for effects

 other than

 Cancer 

44
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 45 

3. HEALTH EFFECTS 

that included a burning sensation in the trachea and a burning cough. The NOAEL of 23 mg/m3 for 

days 1–14 was used to derive an acute-duration inhalation MRL for ethylene glycol as indicated in the 

footnote to Table 3-1 and discussed in Chapter 2 and Appendix A. 

Cardiovascular Effects. Electrocardiographs conducted after 14 and 30 days of exposure were 

normal in a controlled study of 19 volunteers who were exposed to ethylene glycol aerosol for 20– 

22 hours/day for 30 days (Wills et al. 1974). The average mean weekly exposure concentration was 

23 mg/m3 for days 1–14 and 30 mg/m3 for days 1–30. 

No gross or histological effects in the heart occurred in rats (15/concentration), guinea pigs 

(15/concentration), rabbits (3/concentration), dogs (2/concentration), or monkeys (2–3/concentration) that 

were whole-body exposed to apparently aerosolized ethylene glycol in concentrations of 10 or 

57 mg/m3 for 8 hours/day, 5 days/week for 6 weeks, or 12 mg/m3 continuously for 90 days (Coon et al. 

1970). The histology examinations in the rats and guinea pigs were limited to eight animals each. This 

study identified NOAELs of 57 mg/m3 (intermittent exposure) and 12 mg/m3 (continuous exposure) for 

cardiovascular effects, but the relevance of these NOAELs is unclear because intake of ethylene glycol 

from ingestion of aerosol deposited on the fur likely significantly contributed to total dose (Tyl et al. 

1995a, 1995b). 

Hematological Effects. No significant hematologic alterations were found in a controlled study of 

19 volunteers who were exposed to ethylene glycol aerosol for 20–22 hours/day for 30 days (Wills et al. 

1974). The average mean weekly exposure concentration was 23 mg/m3 for days 1–14 and 30 mg/m3 for 

days 1–30. Evaluations were performed approximately every 2–3 days and included hematocrit, 

hemoglobin, total and differential leucocyte counts, and prothrombin time. 

No treatment-related hematological effects were found in rats (15/concentration), guinea pigs 

(15/concentration), rabbits (3/concentration), dogs (2/concentration), or monkeys (2–3/concentration) that 

were whole-body exposed to apparently aerosolized ethylene glycol in concentrations of 10 or 

57 mg/m3 for 8 hours/day, 5 days/week for 6 weeks, or 12 mg/m3 continuously for 90 days (Coon et al. 

1970). Evaluations included hemoglobin concentration, packed erythrocyte volume, total leukocyte 

counts, and prothrombin time. This study identified NOAELs of 57 mg/m3 (intermittent exposure) and 

12 mg/m3 (continuous exposure) for hematological effects, but the relevance of these NOAELs is unclear 

because intake of ethylene glycol from ingestion of aerosol deposited on the fur likely significantly 

contributed to total dose (Tyl et al. 1995a, 1995b). 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 46 

3. HEALTH EFFECTS 

Endocrine Effects. No gross or histological effects occurred in the adrenals in dogs (2/concentration) 

or monkeys (2–3/concentration), or thyroid in dogs (2/concentration), following whole-body exposure to 

apparently aerosolized ethylene glycol in concentrations of 10 or 57 mg/m3 for 8 hours/day, 5 days/week 

for 6 weeks, or 12 mg/m3 continuously for 90 days (Coon et al. 1970). Additional endocrine end points 

were not evaluated. The relevance of these NOAELs is unclear because intake of ethylene glycol from 

ingestion of aerosol deposited on the fur likely significantly contributed to total dose (Tyl et al. 1995a, 

1995b). 

Ocular Effects. Rats (15/concentration), guinea pigs (15/concentration), rabbits (3/concentration), 

dogs (2/concentration), and monkeys (2–3/concentration) were exposed to apparently aerosolized 

ethylene glycol in concentrations of 10 or 57 mg/m3 for 8 hours/day, 5 days/week for 6 weeks, or 

12 mg/m3 continuously for 90 days (Coon et al. 1970). No signs of ocular or nasal irritation were 

observed in any of the animals that were intermittently exposed to ≤57mg/m3 in the 6-week study. In the 

90-day study, continuous exposure to 12 mg/m3 caused moderate to severe eye irritation (erythema, 

edema, and discharge) in all (3/3) rabbits and corneal opacity with possible blindness in 2/15 rats; both 

species were affected within 8 days of the initial exposure. 

3.2.1.3 Immunological and Lymphoreticular Effects 

No studies were located specifically regarding adverse immunological effects in humans or animals after 

inhalation exposure to ethylene glycol. There were no significant alterations in total or differential white 

blood cell counts in a controlled study of 19 volunteers who were exposed to ethylene glycol aerosol for 

20–22 hours/day for 30 days (Wills et al. 1974). The average mean weekly exposure concentration was 

23 mg/m3 for days 1–14 and 30 mg/m3 for days 1–30 (Wills et al. 1974). 

3.2.1.4 Neurological Effects 

Slight headache and backache were occasional complaints in 19 volunteers (incidence and frequency not 

reported) who were exposed to ethylene glycol aerosol for 20–22 hours/day for 30 days in a controlled 

study (Wills et al. 1974). The average mean weekly exposure concentration was 23 mg/m3 for days 1– 

14 and 30 mg/m3 for days 1–30. No effects were seen in electroencephalographs or a battery of 

psychological tests conducted after 14 and 30 days of exposure; the tests evaluated simple reaction time, 

reaction time with discrimination, visual-motor coordination, depth perception, and mental ability 

(encoding and subtraction accuracy). 
 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 47 

3. HEALTH EFFECTS 

No gross or histological effects in the brain or spinal cord occurred in dogs (2/concentration) that were 

whole-body exposed to apparently aerosolized ethylene glycol in concentrations of 10 or 57 mg/m3 for 

8 hours/day, 5 days/week for 6 weeks, or 12 mg/m3 continuously for 90 days (Coon et al. 1970). This 

study identified NOAELs of 57 mg/m3 (intermittent exposure) and 12 mg/m3 (continuous exposure) for 

neurological effects based on small numbers of animals. The relevance of these NOAELs is unclear 

because neurobehavioral function was not evaluated and intake of ethylene glycol from ingestion of 

aerosol deposited on the fur likely significantly contributed to total dose (Tyl et al. 1995a, 1995b). 

The highest NOAEL values and all reliable LOAEL values for neurological effects in each species and 

duration category for ethylene glycol after inhalation exposure are reported in Table 3-1, and plotted in 

Figure 3-1. 

3.2.1.5 Reproductive Effects 

No studies were located regarding reproductive effects in humans after inhalation exposure to ethylene 

glycol. 

Acute-duration developmental toxicity studies of inhaled ethylene glycol in mice and rats are available, 

but all of the studies are confounded by concurrent ingestion exposure to ethylene glycol deposited on the 

fur. Whole-body exposure of pregnant CD-1 mice to 150–2,500 mg/m3 aerosolized ethylene glycol for 

6 hours/day on gestation days (Gd) 6–15 caused a decrease in the number of live fetuses per litter at 

≥1,000 mg/m3

, but no effect on reproductive parameters was observed in CD rats dosed under the same 

regimen (Tyl 1985, 1988a; Tyl et al. 1995a). Both the mouse and rat studies were confounded by 

ingestion of ethylene glycol deposited on the fur of exposed animals and consumed during grooming; the 

authors estimated that ingestion comprised the majority of exposure. In a companion study, nose-only 

exposure of CD-1 mice to 500–2,500 mg/m3 aerosolized ethylene glycol using the same study design 

resulted in no effects on pre- or postimplantation loss (Tyl 1988a; Tyl et al. 1995a). Although this study 

was aimed at reducing confounding from concurrent ingestion exposure, the authors noted that the 

animals in the nose-only experiment were also exposed by ingestion of ethylene glycol deposited on the 

face during nose-only exposure. 
 

 

 

 

 

ETHYLENE GLYCOL 48 

3. HEALTH EFFECTS 

As a result of confounding from exposure via ingestion, NTP-CERHR (2004) characterized the 

developmental toxicity studies as inadequate for the purpose of identifying effect levels for inhalation 

exposure; thus, there are no reliable NOAEL or LOAEL values. 

3.2.1.6 Developmental Effects 

No studies were located regarding developmental effects in humans after inhalation exposure to ethylene 

glycol. 

Acute-duration developmental toxicity studies of inhaled ethylene glycol in mice and rats are available, 

but all of the studies are confounded by concurrent ingestion exposure to ethylene glycol deposited on the 

fur. Groups of 25 pregnant CD-1 mice and CD rats were exposed (whole-body) to target concentrations 

of 0, 150, 1,000, or 2,500 mg/m3 aerosolized ethylene glycol (mass median aerodynamic diameter 

[MMAD] of 2.3 μm) for 6 hours/day on Gd 6–15 (Tyl 1985, 1988a; Tyl et al. 1995a). Fetal evaluations 

included litter size, fetal weight, and external, visceral, and skeletal malformations. Maternal toxicity 

(e.g., increased liver weight in rats and reduced body weight gain in mice) was evident at 2,500 and 

1,000 mg/m3 in rats and mice, respectively (Tyl et al. 1995b). In mice, significant decreases in the 

number of live fetuses per litter and in the weight of live fetuses, as well as increases in the number of late 

resorptions per litter and the incidence of external, visceral, and skeletal malformations were observed at 

target concentrations of ≥1,000 mg/m3

. In rats, reduced ossification at some sites in the axial skeleton 

was observed with exposure to 1,000 and 2,500 mg/m3 (Tyl 1985; Tyl et al. 1995a); however, in an 

Expert Panel Review, NTP-CERHR (2004) concluded that the relationship of this effect to treatment was 

uncertain due to the lack of a dose-response relationship. This study was confounded by significant 

ingestion of ethylene glycol deposited on the fur and consumed during grooming; the authors estimated 

that the ingestion dose comprised the majority of exposure. 

In a follow-up study aimed at reducing the confounding from ingestion exposure, pregnant CD-1 mice 

were exposed nose-only to 0, 500, 1,000, or 2,500 mg/m3 aerosolized ethylene glycol (MMAD 2.6 μm)

(Tyl 1988a; Tyl et al. 1995b). Fetal weight and incidence of external, visceral, and skeletal 

malformations were evaluated in the offspring. In maternal animals, there were no effects other than 

changes in kidney weights. Absolute kidney weight was significantly increased at 1,000 and 

2,500 mg/mg3

, and relative kidney weight was increased at 2,500 mg/m3; however, the increases were 

small (6.6–9.5% higher than controls) and microscopic examination of kidneys showed no 

histopathological changes. At 2,500 mg/m3

, live fetal body weight was significantly reduced, and there 
 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 49 

3. HEALTH EFFECTS 

was a significant increase in the one type of skeletal malformation (fused ribs). Increases in some skeletal 

variations were observed at 2,500 mg/m3

, and one type (extra ossification sites in the sagittal suture) was 

significantly increased at all concentrations. Although this study used restraint to minimize oral exposure, 

the authors noted that oral exposure was possible via grooming of the face after exposure. In addition, 

NTP-CERHR (2004) noted that stress from restraint during nose-only exposure (struggling was observed) 

may have contributed to the developmental effects observed with ethylene glycol, which were similar in 

nature to effects observed in a study of restrained nose-only exposure to water vapor (Tyl et al. 1994). 

All of the available studies of developmental effects after inhalation exposure to ethylene glycol are 

confounded by concurrent ingestion exposure and the single nose-only exposure study is also confounded 

by stress related to restraint during exposure. In its review of these studies, NTP-CERHR (2004) 

concluded that the data are insufficient to identify effect levels from inhaled ethylene glycol in animals; 

thus, there are no reliable NOAEL or LOAEL values. 

3.2.1.7 Cancer 

An epidemiologic study on renal cancer mortality examined the work and health histories of 

1,666 chemical plant employees and found no elevation in the odds ratio for workers exposed to ethylene 

glycol (Bond et al. 1985), although the sample size was quite small. Exposure was presumed to be by 

inhalation. 

No studies were located regarding cancer effects in animals after inhalation exposure to ethylene glycol. 

3.2.2 Oral Exposure 

Ethylene glycol is a colorless, water-soluble liquid with a sweet taste and little or no odor, most 

commonly used as an antifreeze fluid. The ready availability of antifreeze mixtures and the sweet taste 

make ethylene glycol intoxication a significant medical and veterinary problem. Antifreeze mixtures 

contain up to 95% ethylene glycol (Mallya et al. 1986; Siew et al. 1975a). Ingestion is the exposure route 

most commonly associated with adverse effects. 

3.2.2.1 Death 

The American Association of Poison Control Centers (AAPCC) reported 25 fatalities for 2005 due to 

ethylene glycol ingestion (Lai et al. 2006). Other fatal ethylene glycol poisonings included case reports of 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 50 

3. HEALTH EFFECTS 

deaths resulting from accidental or intentional ingestion of ethylene glycol or antifreeze containing 99% 

ethylene glycol (Froberg et al. 2006; Godolphin et al. 1980; Gordon and Hunter 1982; Hantson et al. 

2002; Hewlett et al. 1986; Jacobsen et al. 1984; Leth and Gregersen 2005; Siew et al. 1975a; Zeiss et al. 

1989). A 22-year-old male who ingested 300 mL of antifreeze (approximately 4,071 mg/kg ethylene 

glycol) lapsed into a coma 24 hours after hospital admission and died 24 hours later (Siew et al. 1975a). 

A dose of 7,850 mg/kg can be estimated in the case of a 73-year-old male who consumed 500 mL of 95% 

ethylene glycol and died of myocardial failure after 68 hours (Gordon and Hunter 1982). A 25-year-old 

male who ingested ethylene glycol-based antifreeze in an apparent amount of 225 cc (approximately 

3,600 mg/kg) died within 24 hours of hospital admission (Froberg et al. 2006). In five other fatal cases of 

accidental or intentional poisoning, the amount of ingested ethylene glycol ranged from 150 to 1,500 mL 

(2,379–23,786 mg/kg) (Karlson-Stiber and Persson 1992; Walton 1978). Thus, oral dose of ethylene 

glycol required to cause death in humans is not well defined in the literature. The minimum lethal dose 

for adults is thought to be 1.4 mL/kg of 95% ethylene glycol, or about 1,330 mg ethylene glycol/kg body 

weight (Parry and Wallach 1974; Robinson and McCoy 1989; Siew et al. 1975a). 

A single dose oral LD50 of 4,000 mg/kg was determined in female F344 rats (Clark et al. 1979). Male 

Wistar rats administered 12,900 mg/kg ethylene glycol in a single oral dose had 55% mortality within 

48 hours (Richardson 1973). Pregnant CD-1 mice given 11,090 mg/kg/day ethylene glycol orally on 

Gd 7–14 showed 10% mortality (Schuler et al. 1984) and pregnant rabbits exhibited 42% mortality after 

receiving 2,000 mg/kg/day ethylene glycol orally on Gd 6–19 (Tyl et al. 1993). Cats administered a 

single 4,440–8,880 mg/kg dose by gavage had 100% mortality within 20–36 hours (Penumarthy and 

Oehme 1975). A single gavage dose of 4,180–12,540 mg/kg/day caused 17–100% mortality in dogs 

within 72 hours (Kersting and Nielsen 1965). Dogs administered a single oral dose of 4,880 mg/kg in 

food had 100% mortality within 6 days (Beckett and Shields 1971). 

Intermediate-duration dietary exposure to 1,000 mg/kg/day for 16 weeks caused 20% mortality in male 

Wistar rats, with no deaths occurring in similarly treated male F344 rats; females were not tested (Cruzan 

et al. 2004). Male F344/N rats fed 5,000 mg/kg/day ethylene glycol had 40% mortality after 13 weeks, 

whereas similarly treated females did not die (Melnick 1984). A chronic dietary study of ethylene glycol 

in Sprague-Dawley rats found 100% mortality after 12–24 months in males at 750 mg/kg/day and females 

at 3,000 mg/kg/day (Blood 1965). Male F344 rats given 1,000 mg/kg/day ethylene glycol in the feed all 

died within 16 months (DePass et al. 1986a; Woodside 1982). In a 12-month dietary study in male 

Wistar rats, exposure to 300 mg/kg/day caused 40% mortality (died or were moribund) on days 111–221 

(Corley et al. 2008). 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 51 

3. HEALTH EFFECTS 

All reliable LOAEL and LD50 values for death in each species and duration category for ethylene glycol 

after oral exposure are reported in Table 3-2, and plotted in Figure 3-2. 

3.2.2.2 Systemic Effects 

No studies were located regarding hematological, musculoskeletal, endocrine, hepatic, dermal, ocular, or 

body weight effects in humans after oral exposure to ethylene glycol. 

The highest NOAEL values and all reliable LOAEL values for systemic effects in each species and 

duration category for ethylene glycol after oral exposure are reported in Table 3-2 and Figure 3-2. 

Respiratory Effects. Respiratory system involvement occurs 12–24 hours after ingestion of 

sufficient amounts of ethylene glycol and is considered to be part of a second stage in ethylene glycol 

poisoning (Davis et al. 1997; Hess et al. 2004; Vale 1979). The symptoms include hyperventilation 

(Godolphin et al. 1980; Gordon and Hunter 1982), shallow rapid breathing (Woolf et al. 1992; Zeiss et al. 

1989), and generalized pulmonary edema with calcium oxalate crystals occasionally present in the lung 

parenchyma (Friedman et al. 1962; Johnson et al. 1999; Leth and Gregersen 2005; Pellegrino et al. 2006; 

Vale 1979). Respiratory system involvement appears to be dose-dependent and occurs concomitantly 

with cardiovascular changes. Pulmonary infiltrates and other changes compatible with adult respiratory 

distress syndrome (ARDS) may characterize the second stage of ethylene glycol poisoning (Bey et al. 

2002; Piagnerelli et al. 1999; Taylor et al. 1997). Pulmonary edema can be secondary to cardiac failure, 

ARDS, or aspiration of gastric contents (Walder and Tyler 1994). Symptoms related to acidosis such as 

hyperpnea and tachypnea are frequently observed; however, major respiratory morbidities such as 

pulmonary edema and bronchopneumonia are relatively rare and usually only observed with extreme 

poisoning (e.g., in only 5 of 36 severely poisoned cases) (Friedman et al. 1962; Johnson et al. 1999; 

Karlson-Stiber and Persson 1992; Leth and Gregersen 2005; Parry and Wallach 1974; Piagnerelli et al. 

1999; Verrilli et al. 1987). In one case, respiratory failure occurred in a woman who had consumed 

9,771 mg/kg ethylene glycol (as antifreeze) (Blakeley et al. 1993). Pulmonary hyperemia and edema 

were frequent findings in dogs that ingested unknown lethal amounts of ethylene glycol in cases of 

antifreeze poisoning (Kersting and Nielsen 1965). A generalized soft tissue mineralization that included 

the lungs (interstitial) occurred in male F344 rats exposed to 1,000 mg/kg/day in the diet for 1 year 

(DePass et al. 1986a; Woodside 1982). Histological examinations of the lungs showed no effects in 

Sprague-Dawley rats exposed to ≤7,327 mg/kg/day in drinking water for 10 days or ≤5,744 mg/kg/day in 
125

7070

45

4071

153

2379

N9

4000

N10

11090

N12

2000

16

4332

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral 

a 

Key to 

Figure 

Species 

(Strain) 

Exposure/ 

Duration/ 

Frequency 

(Route) 

ACUTE EXPOSURE Death 

1 Human once 

System 

NOAEL 

(mg/kg/day) 

Less Serious 

(mg/kg/day) 

LOAEL 

Serious 

(mg/kg/day) 

7070 M (death 68 hours after 

ingestion of ethylene glycol) 

Reference Chemical Form 

Gordon and Hunter 198

2 Human once 4071 M (death 48 hours after 

ingestion) 

Siew et al. 1975a 

3 Human once 2379 (death in 6/11) Walton 1978 

4 Rat 

(Fischer 344) 

once (G) 4000 F (24-hour LD50) Clark et al. 1979 

5 Mouse 

(Swiss CD-1) 

8 d Gd 7-14 1 x/d (G) 

11090 F (5/50 died) Schuler et al. 1984 

6 Rabbit 

(New Zealand) 

Systemic 

7 Human 

14 d Gd 6-19 1 x/d (GW) once Metab 

2000 F (8/19 died) 

4332 M (severe metabolic 

acidosis) 

Tyl et al. 1993 Cheng et al. 1987 
127

7070707070707070

55

1123811238

30

2714

53

317131713171

N130

76007600

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

Exposure/ LOAEL 

Duration/ 

a 

Key to Species Frequency NOAEL Less Serious Serious Reference 

Figure (Strain) (Route) System (mg/kg/day) (mg/kg/day) (mg/kg/day) Chemical Form 

8 Human once Resp 7070 M (hyperventilation) Gordon and Hunter 198

Cardio 7070 M (myocardial failure) 

Renal 7070 M (renal failure) Metab 7070 M (metabolic acidosis) 

9 Human once Renal 11238 F (calcium oxalate 

crystalluria) 

Heckerling 1987 

Metab 11238 F (metabolic acidosis) 

10 Human once Renal 2714 M (renal failure) Mallya et al. 1986 

11 Human once Cardio 3171 M (tachycardia, ventricular 

gallop) 

Parry and Wallach 1974 

Renal 3171 M (calcium oxalate 

crystalluria, renal failure) 

Metab 3171 M (metabolic acidosis) 

12 Human once Renal 7600 M (ethylene glycol in urine) Peterson et al. 1981 

Metab 7600 M (metabolic acidosis) 
47

407140714071

49

128401284012840

N16

2500

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

Exposure/ 

Duration/ 

a 

Key to Species Frequency 

Figure (Strain) (Route) 

13 Human once 14 Human once 

(W) 

15 Rat 

(SpragueDawley) 

10 d Gd 6-15 1 x/d (GW) 

LOAEL 

System 

NOAEL 

(mg/kg/day) 

Less Serious 

(mg/kg/day) 

Serious 

(mg/kg/day) 

Reference Chemical Form 

Cardio 4071 M (ventricular tachycardia, Siew et al. 1975a 

cardiac arrest) 

Renal 4071 M (oxalate nephrosis) 

Metab 4071 M (metabolic acidosis) Gastro 12840 M (upper gastrointestinal Spillane et al. 1991 

bleeding) 

Renal 12840 M (renal failure) Metab 12840 M (metabolic acidosis) Bd Wt 2500 F (treatment period weight Marr et al. 1992 

gain decreased 27%; gestational weight gain decreased 13%) 
N17

25001000

2500

1000

2500

113

50001250

25001250

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to 

Figure 

Species 

(Strain) 

Exposure/ 

Duration/ 

Frequency 

(Route) System NOAEL (mg/kg/day) Less Serious (mg/kg/day) 

LOAEL 

Serious 

(mg/kg/day) 

Reference Chemical Form 

16 Rat 

(CD) 

10 d Gd 6-15 1 x/d (GW) 

Hepatic 2500 F Neeper-Bradley 1990, 

Neeper-Bradley et al. 19

Renal 1000 F 2500 F (increased absolute and 

relative kidney weight) 

Bd Wt 1000 F 2500 F (26% decreased body 

weight) 

17 Rat 

(CD) 

10 d Gd 6-15 1 x/d (GW) 

Hepatic 5000 F Price et al. 1985 

Renal 1250 F 2500 F (increased relative 

kidney weight) 

Bd Wt 1250 F (17% decreased body 

weight) 
339

732773272953

7327

732773271343

2615

732773272615 5279

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to 

Figure 

Species 

(Strain) 

Exposure/ 

Duration/ 

Frequency 

(Route) System 

18 Rat 

(SpragueDawley) 

10 d (W) Resp 

Gastro Hemato Musc/skel Hepatic Renal Endocr Dermal Bd Wt 

LOAEL 

NOAEL Less Serious Serious Reference

(mg/kg/day) (mg/kg/day) (mg/kg/day) Chemical Form 

7327 F Robinson et al. 1990 

7327 F 2953 F 7327 F (Decreased hemoglobin,

hematocrit, erythrocytesand total leukocytes)

7327 F 7327 F 1343 M 2615 M (tubular oxalate crystals,

dilation, degenerationand necrosis)

7327 F 7327 F 2615 M 5279 M (13% body weight loss) 
69

25025025050

100

111

3000750

1500

N20

150015001500

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

Exposure/ 

Duration/ 

a 

Key to Species Frequency 

Figure (Strain) (Route) 

19 Mouse 

(B6C3F1) 

4 d (GW) 

20 Mouse 

(CD-1) 

10 d Gd 6-15 1 x/d (GW) 

21 Mouse 

(CD-1) 

10 d Gd 6-15 1 x/d (GW) 

System 

Resp 

Cardio Gastro Hemato Hepatic 

Bd Wt 

Hepatic RenalBd Wt

LOAEL 

NOAEL 

(mg/kg/day) 

Less Serious 

(mg/kg/day) 

Serious 

(mg/kg/day) 

Reference Chemical Form 

250 Hong et al. 1988 

250 

250 

50 F 100 F (bone marrow 

hypocellularity) 

3000 F Price et al. 1985 

750 F 1500 F (31% reduced weight 

gain) 

1500 F 

Tyl 1989; Neeper-Bradl1995 

1500 F 1500 F 
78

10743

N22

2000

2000

2000

73

4440

374

2615

5279

388

250

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to 

Figure 

Species 

(Strain) 

Exposure/ 

Duration/ 

Frequency 

(Route) System NOAEL (mg/kg/day) Less Serious (mg/kg/day) 

LOAEL 

Serious 

(mg/kg/day) 

Reference Chemical Form 

22 Dog once 

(F) Renal 10743 (renal failure, oxalate nephrosis) Grauer et al. 1987 

23 Rabbit 

(New Zealand) 

14 d Gd 6-19 1 x/d (GW) 

Hepatic 2000 F Tyl et al. 1993 

Renal 2000 F (intraluminal oxalate 

crystals, epithelial necrosis, and tubular dilatation and degeneration of the cortical tubules) 

Bd Wt 2000 F 

24 Cat once 

(G) 

Immuno/ Lymphoret 

25 Rat 

(SpragueDawley) 

10 d (W) 

Renal 

2615 M 5279 M (decreased spleen and 

thymus weights) 

4440 (oxalate nephrosis) Penumarthy and Oehm

Robinson et al. 1990 

26 Mouse 

(B6C3F1) 

4 d (GW) 250 Hong et al. 1988 
389

12000

390

12000

N23

9771

15

4332

54

11238

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to Species 

Figure (Strain) 

27 Mouse 

CBA 

28 Mouse 

CBA 

Neurological 

29 Human 30 Human 31 Human 

Exposure/ 

Duration/ 

Frequency 

(Route) System NOAEL (mg/kg/day) Less Serious (mg/kg/day) 

LOAEL 

Serious 

(mg/kg/day) 

Reference Chemical Form 

once (G) 12000 M (increased mortality from E. coli infection, 

decreased number of spleen CFUs, and inhibited antibody formation) 

Zabrodskii and German2000 

once 12000 M (reduced natural killer 

cell activity) 

Zabrodskii et al. 2003 

once 9771 F (unresponsive, 

incontinent, no corneal, gag, or deep-tendon reflexes) 

Blakeley et al. 1993 

once 4332 M (tremors, agitation) Cheng et al. 1987 once 11238 F (unresponsive to deep 

pain, delayed pupillary light reflex, no deep tendon or corneal reflex) 

Heckerling 1987 
29

2714

52

3171

46

4071

48

12840

383

7327

79

10743

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to 

Figure 

32 33 34 35 36 37 

Species 

(Strain) 

Human Human Human Human Rat (SpragueDawley) Dog 

Exposure/ 

Duration/ 

Frequency 

(Route) System NOAEL (mg/kg/day) Less Serious (mg/kg/day) 

LOAEL 

Serious 

(mg/kg/day) 

Reference Chemical Form 

once 2714 M (bilateral facial paralysis, 

hearing loss, absent gag reflex, unilateral facial numbness) 

Mallya et al. 1986 

once 3171 M (ataxia, somnolence, 

slurred speech, stupor, seizures, bilateral 6th nerve paralysis, lethargy) 

Parry and Wallach 1974 

once 4071 (stupor, loss of 

consciousness, coma) 

Siew et al. 1975a 

once 12840 M (unresponsive, 

depressed mental status, dysfunction of cranial nerves 9 and 10) 

Spillane et al. 1991 

10 d (W) 7327 F Robinson et al. 1990 

once (F) 10743 (depression, ataxia) Grauer et al. 1987 
72

4440

356

2500

308

2500

384

52797327

N104

250

306

1500

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to Species 

Figure (Strain) 

38 Cat 

Reproductive 

39 Rat 

(SpragueDawley) 

40 Rat 

(CD) 

41 Rat 

(SpragueDawley) 

42 Mouse 

(B6C3F1) 

43 Mouse 

(CD-1) 

Exposure/ 

Duration/ 

Frequency 

(Route) System NOAEL (mg/kg/day) Less Serious (mg/kg/day) 

LOAEL 

Serious 

(mg/kg/day) 

Reference Chemical Form 

once (G) 4440 (convulsions and coma) Penumarthy and Oehm

10 d Gd 6-15 1 x/d (GW) 

2500 F Marr et al. 1992 

10 d Gd 6-15 1 x/d (GW) 

2500 F Neeper-Bradley 1990, 

Neeper-Bradley et al. 19

10 d (W) 5279 M 

7327 F 

Robinson et al. 1990 

4 d (GW) 250 Hong et al. 1988 

10 d Gd 6-15 1 x/d (GW) 

1500 Tyl 1989; Neeper-Bradl

1995 
100

1000

N29

2500

N30

500

1000

112

1250

2500

N31

750

2500

110

750

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to 

Figure 

Species 

(Strain) 

Exposure/ 

Duration/ 

Frequency 

(Route) System 

LOAEL 

NOAEL 

(mg/kg/day) 

Less Serious 

(mg/kg/day) 

Serious 

(mg/kg/day) 

Reference Chemical Form 

Developmental 

44 Rat 

(Fischer 344) 

10 d Gd 6-15 (F) 

1000 F Maronpot et al. 1983 

45 Rat 

(SpragueDawley) 

10 d Gd 6-15 1 x/d (GW) 

2500 F (increased skeletal 

malformations, decreased extent of ossification) 

Marr et al. 1992 

46 Rat 

(CD) 

10 d Gd 6-15 1 x/d (GW) 

500 F 1000 F (increased skeletal 

malformations) 

Neeper-Bradley 1990, Neeper-Bradley et al. 19

47 Rat 

(CD) 

10 d Gd 6-15 1 x/d (GW) 

1250 F 2500 F (increased skeletal 

malformations, decreased live fetuses/litter) 

Price et al. 1985 

48 Mouse 

(Swiss Crl:CD-1) 

7 d Gd 8-14 1 x/d (GW) 

750 F 2500 (decreased pup body 

weight on ppd 1 and 4) 

Harris et al. 1992 

49 Mouse 

(CD-1) 

10 d Gd 6-15 1 x/d (GW) 

750 F (increased skeletal 

malformations) 

Price et al. 1985 
N32

11090

N33

150

500

N34

2000

345

1000

341

5000

360

2826

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to 

Figure 

Species 

(Strain) 

Exposure/ 

Duration/ 

Frequency 

(Route) System NOAEL (mg/kg/day) Less Serious (mg/kg/day) 

LOAEL 

Serious 

(mg/kg/day) 

Reference Chemical Form 

50 Mouse 

(Swiss CD-1) 

8 d Gd 7-14 1 x/d (G) 

11090 F (decreased numbers of Schuler et al. 1984

viable litters and live pups per litter) 

51 Mouse 

(CD-1) 

10 d Gd 6-15 1 x/d (GW) 

b

150 F Tyl 1989; Neeper-Bradl

1995 

500 (increased total 

malformations) 

52 Rabbit 

(New Zealand) 

14 d Gd 6-19 1 x/d (GW) 

INTERMEDIATE EXPOSURE Death 

53 Rat 

(Wistar) 

16 wk (F) 

2000 F Tyl et al. 1993 

1000 M (2/10 deaths) Cruzan et al. 2004

54 Rat 

(Fischer 344/N) 

13 wk (F) 5000 M (4/10 deaths) Melnick 1984; NTP 199

55 Mouse 

(CD-1) 

2 gen (W) NTP 1986; Morrissey et 

1989; Bolon et al. 1997 2826 M (18% mortality in F1 males) 
343

150

500

500

1000

344

150

500

1000

102

10001000

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to 

Figure 

Species 

(Strain) 

Exposure/ 

Duration/ 

Frequency 

(Route) System NOAEL (mg/kg/day) Less Serious (mg/kg/day) 

LOAEL 

Serious 

(mg/kg/day) 

Reference Chemical Form 

Systemic 

56 Rat 

(Wistar) 

16 wk (F) Renal 

c

150 M 500 M (oxalate crystal 

nephropathy with impaired kidney function) 

Cruzan et al. 2004 

Bd Wt 500 M 1000 M (23% reduced body 

weight gain) 

57 Rat 

(Fischer- 344) 

16 wk (F) Renal 150 M 500 M (oxalate crystals in tubles with normal kidney 

function) 

Cruzan et al. 2004 

Bd Wt 1000 M 

58 Rat 

(Fischer 344) 

3 gen (F) Renal 1000 DePass et al. 1986b 

Bd Wt 1000 
342

112811281128112811281128711128

180

112811281128

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to 

Figure 

Species 

(Strain) 

Exposure/ 

Duration/ 

Frequency 

(Route) System NOAEL (mg/kg/day) Less Serious (mg/kg/day) 

LOAEL 

Serious 

(mg/kg/day) 

Reference Chemical Form 

59 Rat 

(Wistar) 

16 wk (F) Resp 1128 F Gaunt et al. 1974 

Cardio 1128 F Gastro 1128 F Hemato 1128 F Musc/skel 1128 F Hepatic 1128 F Renal 71 M 180 M (renal tubular damage) 

1128 F 

Endocr 1128 F Ocular 1128 F Bd Wt 1128 F 
116

1000010000100001000012502500

5000

2500

100001250

2500

N123

250

1250

1250

2250

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

Exposure/ 

Duration/ 

a 

Key to Species Frequency 

Figure (Strain) (Route) 

60 Rat 

(Fischer 344/N) 

13 wk (F) 

61 Rat 

(CD) 

15 d Gd 6-20 1 x/d (GW) 

System 

Cardio 

Gastro Musc/skel Hepatic Renal Endocr Bd Wt Renal Bd Wt 

LOAEL 

NOAEL 

(mg/kg/day) 

Less Serious 

(mg/kg/day) 

Serious 

(mg/kg/day) 

Reference Chemical Form 

10000 F Melnick 1984; NTP 199

10000 F 10000 F 10000 F 

1250 M 2500 F 

5000 F (increased relative kidney 

weight) 

2500 M (renal tubular oxalate 

crystals, dilation, necrosis, and fibrosis) 

10000 F 

1250 M 2500 M (13% reduced body 

weight gain) 

250 1250 (renal tubular dilatation 

and degeneration) 

NTP 1988 

1250 2250 (21% decreased weight 

gain) 
340

57445744

597

574457444071145

9473087

57445744947

3134

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to 

Figure 

Species 

(Strain) 

Exposure/ 

Duration/ 

Frequency 

(Route) System 

62 Rat 

(SpragueDawley) 

90 d (W) Resp 

Gastro Hemato Musc/skel Hepatic Renal Endocr Dermal Bd Wt 

LOAEL 

NOAEL 

(mg/kg/day) 

Less Serious 

(mg/kg/day) 

Serious 

(mg/kg/day) 

Reference Chemical Form 

5744 F Robinson et al. 1990 

5744 F 

597 F (decreased leukocyte 

level) 

5744 F 5744 F 

407 M 947 M (increased kidney weight 

and tubular oxalate 

1145 F crystals, dilation and 

degeneration) 

3087 F (tubular lesions lower in 

frequency and severity than in males) 

5744 F 5744 F 

947 M 3134 M (17% reduced body 

weight gain) 
362

20002000

2000

20002000

N35

250025002500

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to 

Figure 

Species 

(Strain) 

Exposure/ 

Duration/ 

Frequency 

(Route) System NOAEL (mg/kg/day) Less Serious (mg/kg/day) 

LOAEL 

Serious 

(mg/kg/day) 

Reference Chemical Form 

63 Rat 

(Wistar) 

33 d 1 x/d (GW) 

Cardio 2000 Schladt et al. 1998 

Hepatic 2000 Renal 2000 (oxalate crystals in renal 

tubules and pelvis, tubulopathy, epithelial hyperplasia in renal pelvis) 

Endocr 2000 

Bd Wt 2000 

64 Mouse 

(Swiss Crl:CD-1) 

17 d 1 x/d (GW) 

Hepatic 2500 M Harris et al. 1992 

Renal 2500 M Bd Wt 2500 M 
119

160001600016000160003230

6450

323016000

6450

1600016000

361

28261798

2826

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

Exposure/ 

Duration/ 

a 

Key to Species Frequency 

Figure (Strain) (Route) 

65 Mouse 

(B6C3F1) 

13 wk (F) 

66 Mouse 

(CD-1) 

2 gen (W) 

System 

Resp 

Cardio Gastro Musc/skel Hepatic Renal Endocr Bd Wt Hepatic 

Renal 

LOAEL 

NOAEL 

(mg/kg/day) 

Less Serious 

(mg/kg/day) 

Serious 

(mg/kg/day) 

Reference Chemical Form 

16000 F Melnick 1984; NTP 199

16000 F 16000 F 16000 F 

3230 M 6450 M (hyaline degeneration of 

centrilobular hepatocytes) 

3230 M 

16000 F 

6450 M (mild nephrosis and 

regenerative hyperplasia) 

16000 F 16000 F 

2826 NTP 1986; Morrissey et 

1989; Bolon et al. 1997 

1798 M 2826 M (tubular oxalate crystals, 

dilation and degeneration in F0 males) 
382

1128

371

10000

385

5744

364

2000

369

16000

391

1128

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to 

Figure 

Species 

(Strain) 

Exposure/ 

Duration/ 

Frequency 

(Route) System NOAEL (mg/kg/day) Less Serious (mg/kg/day) 

LOAEL 

Serious 

(mg/kg/day) 

Reference Chemical Form 

Immuno/ Lymphoret 

67 Rat 

(Wistar) 

16 wk (F) 1128 F Gaunt et al. 1974 

68 Rat 

(Fischer 344/N) 

13 wk (F) 10000 F Melnick 1984; NTP 199

69 Rat 

(SpragueDawley) 

90 d (W) 5744 F Robinson et al. 1990 

70 Rat 

(Wistar) 

33 d 1 x/d (GW) 

2000 Schladt et al. 1998 

71 Mouse 

(B6C3F1) 

13 wk (F) 16000 F Melnick 1984; NTP 199

Neurological 

72 Rat 

(Wistar) 

16 wk (F) 1128 F Gaunt et al. 1974 
115

2500

5000

386

5744

365

2000

368

16000

101

1000

381

7151128

372

500010000

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to 

Figure 

Species 

(Strain) 

Exposure/ 

Duration/ 

Frequency 

(Route) System NOAEL (mg/kg/day) Less Serious (mg/kg/day) 

LOAEL 

Serious 

(mg/kg/day) 

Reference Chemical Form 

73 Rat 

(Fischer 344\N) 

13 wk (F) 2500 M 5000 M (calcium oxalate deposits in brain blood vessel 

walls) 

Melnick 1984; NTP 199

74 Rat 

(SpragueDawley) 

90 d (W) 5744 M Robinson et al. 1990 

75 Rat 

(Wistar) 

33 d 1 x/d (GW) 

2000 F Schladt et al. 1998 

76 Mouse 

(B6C3F1) 

Reproductive 

77 Rat 

(Fischer 344) 

13 wk (F) 3 gen (F) 

16000 F 

1000 

Melnick 1984; NTP 199DePass et al. 1986b 

78 Rat 

(Wistar) 

16 wk (F) 715 M 

1128 F 

Gaunt et al. 1974 

79 Rat 

(Fischer 344/N) 

13 wk (F) 5000 M 

10000 F 

Melnick 1984; NTP 199
309

1250

2250

387

31345744

363

2000

N37

2500

N38

750

2500

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to Species 

Figure (Strain) 

80 Rat 

(CD) 

81 Rat 

(SpragueDawley) 

82 Rat 

(Wistar) 

83 Mouse 

(Swiss Crl:CD-1) 

84 Mouse 

(Swiss Crl:CD-1) 

Exposure/ 

Duration/ 

Frequency 

(Route) System NOAEL (mg/kg/day) Less Serious (mg/kg/day) 

LOAEL 

Serious 

(mg/kg/day) 

Reference Chemical Form 

15 d Gd 6-20 1 x/d (GW) 

1250 F 2250 decreased postnatal 

viability) 

NTP 1988 

90 d (W) 3134 M 

5744 F 

Robinson et al. 1990 

33 d 1 x/d (GW) 

2000 Schladt et al. 1998 

17 d 1 x/d (GW) 

2500 M Harris et al. 1992 

20 d 1 x/d (GW) 

750 2500 (decreased live fetuses, 

increased dead implants, 2/6 litters totally resorbed) 

Harris et al. 1992 
N106

840

1640

370

1290016000

359

8971798

1798 2826

N122

1250

2250

358

897

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to Species 

Figure (Strain) 

85 Mouse 

(CD-1) 

86 Mouse 

(B6C3F1) 

87 Mouse 

(CD-1) 

Developmental 

88 Rat 

(CD) 

89 Mouse 

(CD-1) 

Exposure/ 

Duration/ 

Frequency 

(Route) 

15-18 wk (W) 13 wk (F) 2 gen (W) 15 d Gd 6-20 1 x/d (GW) 2 gen (W) 

NOAEL 

System (mg/kg/day) 

840 

12900 M 16000 F 

897 M 

1798 F 1250 F 

LOAEL 

Less Serious Serious 

(mg/kg/day) (mg/kg/day) 

1640 (slightly decreased 

numbers of litters/mating pair and live pups/litter) 

1798 M (reduced seminal vesicle 2826 (testicular degeneration 

and epididymis weights in F0 and F1 males; 

and sperm motility in F1 reduced live F0 female males) and total pups per litter) 

2250 (decreased postnatal 

viability, increased malformations in axial skeleton) 

897 F (reduced pup weight in

F0 females)

Reference Chemical Form 

Lamb et al. 1985 Melnick 1984; NTP 199NTP 1986; Morrissey et 1989; Bolon et al. 1997 NTP 1988 NTP 1986; Morrissey et 1989; Bolon et al. 1997 
123

7503000

394

300

348

1000

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to 

Figure 

Species 

(Strain) 

Exposure/ 

Duration/ 

Frequency 

(Route) 

CHRONIC EXPOSURE Death 

90 Rat 

(SpragueDawley) 

2 yr (F) 

System 

NOAEL 

(mg/kg/day) 

Less Serious 

(mg/kg/day) 

LOAEL 

Serious 

(mg/kg/day) 

750 M (100% mortality within 

100 days) 

Reference Chemical Form 

Blood 1965 

3000 F (100% mortality during 

second year) 

91 Rat 

(Wistar) 

12 mo (F) 300 M (4/10 died or were moribund on days 

111-221) 

Corley et al. 2008 

92 Rat 

(Fischer 344) 

16 mo (F) 1000 M (100% dead or moribund by day 475) DePass et al. 1986a; Woodside 1982 
355

30003000150375

375750

3000375

750

393

150

300

300

400

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to 

Figure 

Species 

(Strain) 

Exposure/ 

Duration/ 

Frequency 

(Route) System NOAEL (mg/kg/day) Less Serious (mg/kg/day) 

LOAEL 

Serious 

(mg/kg/day) 

Reference Chemical Form 

Systemic 

93 Rat 

(SpragueDawley) 

2 yr (F) Gastro 3000 F Blood 1965 

Hepatic 3000 F Renal 150 M 

375 F 

375 M (renal tubular oxalate 

crystal deposition and degenerative changes) 

750 F (renal tubular oxalate 

crystal deposition and degenerative changes) 

Endocr 3000 F Bd Wt 375 M 750 M (30% decreased body 

weight gain within 100 days) 

94 Rat 

(Wistar) 

12 mo (F) Renal 150 M 300 M (oxalate nephrosis and bladder inflammation and 

hemorrhage) 

Corley et al. 2008 

Bd Wt 300 M 400 M (31% reduced body 

weight gain on day 197) 
333

200 1000200

1000

200

1000

200

1000

100040

200

200

1000

1000

100010001000200

1000

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

Exposure/

Duration/

a Frequency Key to Species (Route) Figure (Strain) System 

95 Rat 24 mo Resp (Fischer 344) (F) 

Cardio Gastro Hemato Musc/skel Hepatic Renal Endocr Dermal Ocular Bd Wt 

LOAEL 

NOAEL 

(mg/kg/day) 

Less Serious 

(mg/kg/day) 

Serious 

(mg/kg/day) 

Reference Chemical Form 

200 M 1000 M (mineralization in lungs) DePass et al. 1986a; 

Woodside 1982 

200 M 1000 M (mineralization in heart 

vessels and muscle) 

200 M 1000 M (mineralization in 

stomach) 

200 M 1000 M (mineralization in 

vascular system, decreased erythrocytes, hematocrit and hemoglobin) 

1000 

40 F 200 F (slight fatty 

metamorphosis) 

200 1000 F (increased kidney weight 1000 M (oxalate nephrosis) 

and crystalluria without lesions) 

1000 1000 1000 

200 M 1000 M (15% decreased body 

weight gain) 
350

1000100010001000100010001000100010001000

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to 

Figure 

Species 

(Strain) 

Exposure/ 

Duration/ 

Frequency 

(Route) System 

96 Mouse 

(CD-1) 

24 mo (F) Resp 

Cardio Gastro Musc/skel Hepatic Renal Endocr Dermal Ocular Bd Wt 

LOAEL 

NOAEL 

(mg/kg/day) 

Less Serious 

(mg/kg/day) 

Serious 

(mg/kg/day) 

Reference Chemical Form 

1000 DePass et al. 1986a; 

Woodside 1982 

1000 

1000 

1000 1000 1000 1000 1000 1000 

1000 
353

3000

120001200012000120001500

3000

300012000

6000

120001200012000

367

3000

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

Exposure/

Duration/

a Frequency Key to Species (Route) Figure (Strain) System 

97 Mouse 24 mo Resp (B6C3F1) (F) 

Cardio Gastro Hemato Musc/skel Hepatic Renal Endocr Dermal Bd Wt 

Immuno/ Lymphoret 

98 Rat 2 yr 

(Sprague- (F) Dawley) 

LOAEL 

NOAEL 

(mg/kg/day) 

Less Serious 

(mg/kg/day) 

Serious 

(mg/kg/day) 

Reference Chemical Form 

3000 F (medial hyperplasia of NTP 1993 

pulmonary arterioles) 

12000 F 12000 F 12000 F 12000 F 

1500 M 3000 M (hepatocellular hyaline 

degeneration) 

3000 M 6000 M (oxalate-like crystals and 

calculi in tubules)

12000 F 12000 F 12000 F 12000 F 

3000 F Blood 1965 
349

200

1000

377

1000

379

12000

366

3000

375

1000

376

200

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to 

Figure 

Species 

(Strain) 

Exposure/ 

Duration/ 

Frequency 

(Route) System NOAEL (mg/kg/day) Less Serious (mg/kg/day) 

LOAEL 

Serious 

(mg/kg/day) 

Reference Chemical Form 

99 Rat 

(Fischer 344) 

24 mo (F) 200 F 1000 F (hemosiderosis in mesenteric lymph nodes) DePass et al. 1986a; Woodside 1982 

100 Mouse 

(CD-1) 

24 mo (F) 1000 DePass et al. 1986a; Woodside 1982 

101 Mouse 

(B6C3F1) 

24 mo (F) 12000 F NTP 1993 

Neurological 

102 Rat 

(SpragueDawley) 

103 Rat 

(Fischer 344) 

2 yr (F) 24 mo (F) 

3000 F 1000 

Blood 1965 DePass et al. 1986a; Woodside 1982 

104 Mouse 

(CD-1) 

24 mo (F) 200 DePass et al. 1986a; Woodside 1982 
380

12000

346

1000

351

1000

378

600012000

Table 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (continued) 

a 

Key to 

Figure 

Species 

(Strain) 

Exposure/ 

Duration/ 

Frequency 

(Route) System NOAEL (mg/kg/day) Less Serious (mg/kg/day) 

LOAEL 

Serious 

(mg/kg/day) 

Reference Chemical Form 

105 Mouse 

(B6C3F1) 

24 mo (F) 12000 F NTP 1993 

Reproductive 

106 Rat 

(Fischer 344) 

24 mo (F) 1000 DePass et al. 1986a; Woodside 1982 

107 Mouse 

(CD-1) 

24 mo (F) 1000 DePass et al. 1986a; Woodside 1982 

108 Mouse 

(B6C3F1) 

24 mo (F) 6000 M 

12000 F 

NTP 1993 

a The number corresponds to entries in Figure 3-2. b An acute-duration oral minimal risk level (MRL) of 0.8 mg/kg/day was derived from a BMDL10 of 76 mg/kg/day based on benchmark dose analysis of the incidenctotal malformations and incidences of bilateral extra rib 14; the BMDL10 was divided by an uncertainty factor of 100 (10 for extrapolation from animals to humans avariability. c An intermediate-duration MRL based on Cruzan et al. (2004) would be higher than the acute-duration MRL, as discussed in Section 2.3. Because available evidethe acute-duration MRL should be protective for kidney effects following longer-term exposure, the acute-duration value of 0.8 mg/kg/day was adopted for intermedexposure. Bd Wt = body weight; Cardio = cardiovascular; CFU = colony forming unit; d = day(s); (F)= feed; F = Female; (G) = gavage; Gastro = gastrointestinal; Gd = gestatiogastrointestinal; (GW) = gavage in water; Hemato = hematological; Immuno/Lymphoret = immunological/lymphoreticular; LD50 = lethal dose, 50% kill; LOAEL = lowest-observed-adverse-effect level; M = male; mo = month(s); Metab = metabolic; NOAEL = no-observed-adverse-effect level; ppd = post-parturition day; Resp = time(s); (W) = drinking water; wk = week(s); yr = year(s) 
Death 

Respiratory Cardiovascular Gastrointestinal Hematological Musculoskeletal Hepatic Renal Endocrine Dermal Body Weight 

Figure 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral 

Acute (≤14 days) 

Systemic 

mg/kg/day 

100000 

14 14 5m 22d 9 00 

1 8 18r 8 18r 18r 18r 18r 8 12 18r 18r

17r 18r

2 4r 13 24c 13

11 18r 20m 11

3 16r 10 16r 17r 18r 15r 16r 18r

6h 23h 23h 23h 

21m 21m 18r 20m 21m 17r 17r 00 16r 16r

20m 

19m 19m 19m 

00 19m 

19m 

10 

100

10

1

1 

0.1 

ETHYLENE GLYCOL

3. HEALTH EFFECTS

c-Cat 

81

d-Dog

r-Rat 

p-Pig

q-Cow

 -Humans 

k-Monkey

m-Mouse 

h-Rabbit 

a-Sheep 

f-Ferret 

j-Pigeon

e-Gerbil 

s-Hamster 

g-Guinea Pig 

n-Mink 

o-Other

 Cancer Effect Level-Animals

 LOAEL, More Serious-Animals

LOAEL, Less Serious-Animals

NOAEL - Animals

 Cancer Effect Level-Humans

 LOAEL, More Serious-Humans

LOAEL, Less Serious-Humans

NOAEL - Humans

 LD50/LC50

Minimal Risk Level

 for effects

 other than

 Cancer 
Metabolic 

Immuno/LymphoNeurological Reproductive Developmental 

100000 

mg/kg/day 

14 27m 28m 35

10000 9 37d 29 31 50m

8 12 36r 41r

25r 41r 7 13 38c 30 34

11 33 25r 32 39r 40r 48m 45r 47r 52h 

43m 47r 1000 44r 46r 

48m 49m 

51m 46r 

26m 42m 

51m
	

100
	

10 

1 

0.1 

c-Cat 

d-Dog

r-Rat 

p-Pig

q-Cow

 -Humans 

k-Monkey

m-Mouse 

h-Rabbit 

a-Sheep 

f-Ferret 

j-Pigeon

e-Gerbil 

s-Hamster 

g-Guinea Pig 

n-Mink 

o-Other

 Cancer Effect Level-Animals

 LOAEL, More Serious-Animals

LOAEL, Less Serious-Animals

NOAEL - Animals

 Cancer Effect Level-Humans

 LOAEL, More Serious-Humans

LOAEL, Less Serious-Humans

NOAEL - Humans

 LD50/LC50

Minimal Risk Level

 for effects

 other than

 Cancer 

r 

Figure 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (Continued)
 

Acute (≤14 days)
	

Systemic
	

ETHYLENE GLYCOL

3. HEALTH EFFECTS

82
Death 

Respiratory Cardiovascular Gastrointestinal Hematological Musculoskeletal Hepatic Renal Endocrine Dermal Ocular 

mg/kg/day 

100000 

65m 65m 65m 65m 65m 65m
	

10000
	 60r 60r 60r 60r 60r 

65m 65m 62r 62r 62r 62r 62r 62r 54r 60r 

65m 65m 62r 55m 66m 66m 64m 64m 60r 60r 

63r 63r 63r 63r 66m 

60r 61r 59r 59r 59r 59r 59r 59r 59r 62r 59r 59r 1000 53r 58r 62r 

62r 

56r 57r 

62r 

61r 

59r 

56r 57r
	

100
	

59r 

10 

c-Cat 

d-Dog

r-Rat 

p-Pig

q-Cow

 -Humans 

k-Monkey

m-Mouse 

h-Rabbit 

a-Sheep 

f-Ferret 

j-Pigeon

e-Gerbil 

s-Hamster 

g-Guinea Pig 

n-Mink 

o-Other

 Cancer Effect Level-Animals

 LOAEL, More Serious-Animals

LOAEL, Less Serious-Animals

NOAEL - Animals

 Cancer Effect Level-Humans

 LOAEL, More Serious-Humans

LOAEL, Less Serious-Humans

NOAEL - Humans

 LD50/LC50

Minimal Risk Level

 for effects

 other than

 Cancer 

Figure 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (Continued)

Intermediate (15-364 days) 

Systemic 

ETHYLENE GLYCOL

3. HEALTH EFFECTS

83
Body Weight 

Immuno/LymNeurological Reproductive Development

100000 

mg/kg/day 

65m 71m 76m 86m 

86m 

10000 68r 79r 

69r 74r 81r 73r 79r 

62r 81r 87m 64m 60r 73r 83m 84m 61r 80r 88r 63r 70r 75r 82r 87m 87m 85m 

60r 61r 80r 88r 59r 67r 72r 78r 1000 56r 57r 58r 62r 77r

85m 87m 89m

84m 78r 

56r 

100 

10 

c-Cat 

d-Dog

r-Rat 

p-Pig

q-Cow

 -Humans 

k-Monkey

m-Mouse 

h-Rabbit 

a-Sheep 

f-Ferret 

j-Pigeon

e-Gerbil 

s-Hamster 

g-Guinea Pig 

n-Mink 

o-Other

 Cancer Effect Level-Animals

 LOAEL, More Serious-Animals

LOAEL, Less Serious-Animals

NOAEL - Animals

 Cancer Effect Level-Humans

 LOAEL, More Serious-Humans

LOAEL, Less Serious-Humans

NOAEL - Humans

 LD50/LC50

Minimal Risk Level

 for effects

 other than

 Cancer 

phor 

al 

Figure 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (Continued)
 

Intermediate (15-364 days)
	

Systemic
	

ETHYLENE GLYCOL

3. HEALTH EFFECTS

84
mg/kg/day Death 

RespiratoryCardiovascGastrointesHematologiMusculoskeHepatic Renal Endocrine Dermal 

100000 

97m 97m 97m 97m 97m 97m 97m 

10000 

97m 

90r 97m 93r 97m 93r 97m 93r 

97m 

1000 92r 96m 95r 96m 95r 96m 95r 95r 96m 95r 96m 96m 95r 95r 96m 95r 96m 95r 

90r 93r 

93r 93r 

91r 94r 

95r 95r 95r 95r 95r 95r 

93r 94r 

100 

95r 

10 

c-Cat 

d-Dog

r-Rat 

p-Pig

q-Cow

 -Humans 

k-Monkey

m-Mouse 

h-Rabbit 

a-Sheep 

f-Ferret 

j-Pigeon

e-Gerbil 

s-Hamster 

g-Guinea Pig 

n-Mink 

o-Other

 Cancer Effect Level-Animals

 LOAEL, More Serious-Animals

LOAEL, Less Serious-Animals

NOAEL - Animals

 Cancer Effect Level-Humans

 LOAEL, More Serious-Humans

LOAEL, Less Serious-Humans

NOAEL - Humans

 LD50/LC50

Minimal Risk Level

 for effects

 other than

 Cancer 

ular 

tinal 

cal 

letal 

Figure 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (Continued)
 

Chronic (≥365 days)
	

Systemic 

ETHYLENE GLYCOL

3. HEALTH EFFECTS

85
Ocular 

Body Weight Immuno/Lymphor Neurological Reproductive 

100000 

Systemic
	

mg/kg/day 

97m 101m 105m 108m 

10000 

108m 

98r 102r 

1000 96m 95r 96m 95r 100m 99r 103r 107m 106r 

93r 

94r 93r 

94r 

95r 99r 104m 

100 

10 

c-Cat 

d-Dog

r-Rat 

p-Pig

q-Cow

 -Humans 

k-Monkey

m-Mouse 

h-Rabbit 

a-Sheep 

f-Ferret 

j-Pigeon

e-Gerbil 

s-Hamster 

g-Guinea Pig 

n-Mink 

o-Other

 Cancer Effect Level-Animals

 LOAEL, More Serious-Animals

LOAEL, Less Serious-Animals

NOAEL - Animals

 Cancer Effect Level-Humans

 LOAEL, More Serious-Humans

LOAEL, Less Serious-Humans

NOAEL - Humans

 LD50/LC50

Minimal Risk Level

 for effects

 other than

 Cancer 

Figure 3-2 Levels of Significant Exposure to Ethylene Glycol - Oral (Continued)
 

Chronic (≥365 days)
	 ETHYLENE GLYCOL

3. HEALTH EFFECTS

86
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 87 

3. HEALTH EFFECTS 

drinking water for 90 days (Robinson et al. 1990), Wistar rats exposed to ≤2,000mg/kg/day by gavage for 

4 weeks (Schladt et al. 1998), Wistar rats exposed to ≤1,128mg/kg/day in the diet for 16 weeks (Gaunt et 

al. 1974), F344 rats exposed to ≤10,000 mg/kg/day in the diet for 13 weeks (Melnick 1984), SpragueDawley rats exposed to ≤3,000 mg/kg/day in the diet for 2 years (Blood 1965), B6C3F1 mice exposed to 

≤250 mg/kg/day by gavage for 4 days (Hong et al. 1988), B6C3F1 mice exposed to ≤16,000 mg/kg/day in 

the diet for 13 weeks or ≤12,000 mg/kg/day in the diet for 2 years (Melnick 1984; NTP 1993), or 

CD-1 mice exposed to ≤1,000 mg/kg/day in the diet for 2 years (DePass et al. 1986a; Woodside 1982). 

The 10- and 90-day drinking water studies in rats also found no histopathological changes in the nasal 

cavity or turbinates (Robinson et al. 1990). 

Cardiovascular Effects. Cardiovascular system involvement in humans occurs at the same time as 

respiratory system involvement, during the second phase of oral ethylene glycol poisoning, which is 12– 

24 hours after acute exposure (Vale 1979). The symptoms of cardiac involvement include tachycardia, 

ventricular gallop (Morgan et al. 2000; Parry and Wallach 1974; Siew et al. 1975a), and cardiac 

enlargement (Friedman et al. 1962; Vale 1979; Verrilli et al. 1987). Repeated cardiac arrhythmias were 

observed prior to cardiac arrest and death in a 22-year-old man who ingested 4,071 mg/kg of ethylene 

glycol (Siew et al. 1975a). Ingestion of ethylene glycol may also cause hypertension or hypotension, 

which may progress to cardiogenic shock (Chung and Tuso 1989; Jobard et al. 1996; Morgan et al. 2000; 

Rasic et al. 1999; Walder and Tyler 1994). Episodes of hypotension were observed prior to renal failure 

and death in a 73-year-old man who ingested 7,850 mg/kg ethylene glycol, contained in antifreeze 

(Gordon and Hunter 1982). Myocarditis has been observed at autopsy in cases of people who died 

following acute ingestion of ethylene glycol (Friedman et al. 1962). As in the case of respiratory effects, 

cardiovascular involvement occurs with ingestion of relatively high doses of ethylene glycol. 

Nevertheless, circulatory disturbances are a rare occurrence, having been reported in only 8 of 36 severely 

poisoned cases (Karlson-Stiber and Persson 1992). Therefore, it appears that acute exposure to high 

levels of ethylene glycol can cause serious cardiovascular effects in humans. The effects of a long-term, 

low-dose exposure are unknown. 

Edema of the heart was occasionally observed in dogs that ingested unknown lethal amounts of ethylene 

glycol in cases of antifreeze poisoning (Kersting and Nielsen 1965). A generalized soft tissue 

mineralization that included the heart (vessels and muscle) occurred in male F344 rats exposed to 

1,000 mg/kg/day in the diet for 1 year (DePass et al. 1986a; Woodside 1982). Histological examinations 

of the heart showed no effects in Wistar rats exposed to ≤2,000mg/kg/day by gavage for 4 weeks 

(Schladt et al. 1998), F344 rats exposed to ≤10,000 mg/kg/day in the diet for 13 weeks (Melnick 1984), 
 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 88 

3. HEALTH EFFECTS 

Wistar rats exposed to ≤1,128 mg/kg/day in the diet for 16 weeks (Gaunt et al. 1974), B6C3F1 mice 

exposed to ≤250 mg/kg/day by gavage for 4 days (Hong et al. 1988), B6C3F1 mice exposed to 

≤16,000 mg/kg/day in the diet for 13 weeks or ≤12,000 mg/kg/day in the diet for 2 years (Melnick 1984; 

NTP 1993), or CD-1 mice exposed to ≤1,000 mg/kg/day in the diet for 2 years (DePass et al. 1986a; 

Woodside 1982). 

Gastrointestinal Effects. Nausea, vomiting with or without blood, pyrosis, and abdominal cramping 

and pain are common early effects of acute ethylene glycol ingestion (Davis et al. 1997; Johnson et al. 

1999; Moossavi et al. 2003; Singh et al. 2001; Verrilli et al. 1987). Hemorrhagic areas in the gastric 

mucosa were observed at autopsy in a case of fatal oral poisoning with ethylene glycol (Hantson et al. 

2002). Ischemic hemorrhagic necrosis of the colon was possibly ethylene glycol-related in a case of acute 

oral poisoning due to the absence of any other apparent causes (Singh et al. 2001). Acute effects of 

ethylene glycol ingestion in another patient included intermittent diarrhea and abdominal pain, which 

were attributed to mild colonic ischemia; severe abdominal pain secondary to colonic stricture and 

perforation developed 3 months after ingestion, and histology of the resected colon showed birefringent 

crystals highly suggestive of oxalate deposition (Gardner et al. 2003, 2004). 

A 33-year-old man who drank a quart of ethylene glycol (12,840 mg/kg) developed upper gastrointestinal 

tract bleeding secondary to multiple gastric lesions (Spillane et al. 1991). It is not clear whether or not the 

gastric lesions were a pre-existing condition in this patient. 

A generalized soft tissue mineralization that included the stomach, but not other parts of the 

gastrointestinal tract, occurred in male F344 rats exposed to 1,000 mg/kg/day in the diet for 1 year 

(DePass et al. 1986a; Woodside 1982). Histological examinations of the gastrointestinal tract showed no 

effects in Sprague-Dawley rats exposed to ≤7,327 mg/kg/day in drinking water for 10 days or 

≤5,744 mg/kg/day in drinking water for 90 days (Robinson et al. 1990), F344 rats exposed to 

≤10,000 mg/kg/day in the diet for 13 weeks (Melnick 1984), Wistar rats exposed to ≤1,128mg/kg/day in 

the diet for 16 weeks (Gaunt et al. 1974), Sprague-Dawley rats exposed to ≤3,000 mg/kg/day in the diet 

for 2 years (Blood 1965), B6C3F1 mice exposed to ≤250 mg/kg/day by gavage for 4 days (Hong et al. 

1988), B6C3F1 mice exposed to ≤16,000 mg/kg/day in the diet for 13 weeks or ≤12,000 mg/kg/day in the 

diet for 2 years (Melnick 1984; NTP 1993), or CD-1 mice exposed to ≤1,000 mg/kg/day in the diet for 

2 years (DePass et al. 1986a; Woodside 1982). 
 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 89 

3. HEALTH EFFECTS 

Hematological Effects. Initial laboratory findings in cases of acute ethylene glycol poisoning may 

include moderate leukocytosis with a predominance of polymorphonuclear neutrophils and a normal 

hematocrit (Davis et al. 1997; Parry and Wallach 1974; Reddy et al. 2007; Verrilli et al. 1987). 

No effects were observed on hematology parameters, but dose-related effects on bone marrow and 

erythropoietic parameters were observed when gavage doses up to 250 mg/kg/day ethylene glycol were 

given for 4 consecutive days to B6C3F1 mice (Hong et al. 1988). Granulocyte-macrophage progenitor 

formation was suppressed in males exposed to 50 mg/kg/day and in both sexes at higher doses. Ethylene 

glycol treatment resulted in bone marrow hypocellularity in both sexes up to 14 days after dosing at 

100 mg/kg/day. Iron uptake in the bone marrow was suppressed in males exposed to 250 mg/kg/day; 

erythroid precursor colony-forming units were not significantly affected in mice at any dose. The 

biological significance of the bone marrow effects is uncertain in the absence of supporting data from 

other studies, as summarized below. 

No histological changes in the bone marrow were observed in mice or rats exposed to higher doses of 

ethylene glycol for longer durations; these included F344 rats exposed to ≤10,000 mg/kg/day in the diet 

for 13 weeks (Melnick 1984), Sprague-Dawley rats exposed to ≤7,327 mg/kg/day in drinking water for 

10 or 90 days (Robinson et al. 1990), and B6C3F1 mice exposed to ≤16,000 mg/kg/day in the diet for 

13 weeks or ≤12,000 mg/kg/day in the diet for 2 years (Melnick 1984; NTP 1993). Results of routine 

hematology evaluations in these studies were unremarkable except for some alterations in 10- and 90-day 

studies in rats. In the 10-day study, statistically significant decreases in hemoglobin, hematocrit, 

erythrocytes, and total leukocytes (7.3, 8.9, 8.5, and 34.8% less than controls, respectively) occurred in 

female rats at 7,327 mg/kg/day (Robinson et al. 1990). In the 90-day study, total leukocyte counts were 

significantly reduced in female rats at 597, 3,087 and 5,744 mg/kg/day (32, 30, and 50% less than 

controls, respectively) (Robinson et al. 1990). Results of differential counts were not reported and no 

clear hematological changes occurred in male rats in either study. Hematology evaluations were also 

negative in studies that did not examine bone marrow histology; these included studies of Wistar rats 

exposed to ≤2,000 mg/kg/day by gavage for 33 days (Schladt et al. 1998), Wistar rats exposed to 

≤1,128 mg/kg/day in the diet for 16 weeks (Gaunt et al. 1974), and CD-1 mice exposed to 

≤1,000 mg/kg/day in the diet for 2 years (DePass et al. 1986a). Hematological changes (decreased 

erythrocyte count and hematocrit and hemoglobin concentration, and increased neutrophil count) were 

observed in male F344 rats exposed to 1,000 mg/kg/day in the diet for 1 year, although this dose was a 

serious LOAEL for renal toxicity and mortality (DePass et al. 1986a). 
 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 90 

3. HEALTH EFFECTS 

Musculoskeletal Effects. Reported musculoskeletal effects in cases of acute ethylene glycol 

poisoning have included diffuse muscle tenderness and myalgias associated with elevated serum 

creatinine phosphokinase levels, and myoclonic jerks and tetanic contractions associated with 

hypocalcemia (Davis et al. 1997; Friedman et al. 1962; Parry and Wallach 1974; Verrilli et al. 1987). In 

some of these cases, autopsies showed interstitial and parenchymatous myositis in skeletal muscle 

(Friedman et al. 1962; Verrilli et al. 1987). 

Histological examinations of skeletal muscle and/or bone in acute-, intermediate- and chronic-duration 

studies of ethylene glycol showed no effects in rats or mice. These studies included Sprague-Dawley rats 

exposed to ≤7,327 mg/kg/day in drinking water for 10 days or ≤5,744 mg/kg/day in drinking water for 

90 days (Robinson et al. 1990), Wistar rats exposed to ≤1,128mg/kg/day in the diet for 16 weeks (Gaunt 

et al. 1974), F344 rats exposed to ≤10,000 mg/kg/day in the diet for 13 weeks (Melnick 1984) or 

1,000 mg/kg/day in the diet for 2 years (DePass et al. 1986a; Woodside 1982), B6C3F1 mice exposed to 

≤16,000 mg/kg/day in the diet for 13 weeks or ≤12,000 mg/kg/day in the diet for 2 years (Melnick 1984; 

NTP 1993), or CD-1 mice exposed to ≤1,000 mg/kg/day in the diet for 2 years (DePass et al. 1986a; 

Woodside 1982). 

Hepatic Effects. Central hydropic or fatty degeneration, parenchymal necrosis, and calcium oxalate 

crystals in the liver have been observed at autopsy in cases of people who died following acute ingestion 

of ethylene glycol (Friedman et al. 1962; Leth and Gregersen 2005; Verrilli et al. 1987). 

Acute-duration studies of ethylene glycol showed no effects on liver weight or liver histology in SpragueDawley rats exposed to ≤7,327 mg/kg/day in drinking water for 10 days (Robinson et al. 1990) or 

B6C3F1 mice exposed to ≤250 mg/kg/day by gavage for 4 days (Hong et al. 1988). Developmental 

toxicity studies found no effect on maternal liver weight (histology not examined) in CD rats exposed to 

≤5,000 mg/kg/day by gavage on Gd 6–15 (Neeper-Bradley 1990; Neeper-Bradley et al. 1995; Price et al. 

1985), CD-1 mice exposed to ≤3,000 mg/kg/day by gavage on Gd 6–15 (Neeper-Bradley et al. 1995; 

Price et al. 1985; Tyl 1989), or New Zealand rabbits exposed to ≤2,000mg/kg/day by gavage on Gd 6–19 

(Tyl et al. 1993). 

Histopathologic changes in the liver were reported in one intermediate-duration study in mice (Melnick 

1984), one chronic study in mice (NTP 1993), and one chronic study in rats (DePass et al. 1986a; 

Woodside 1982). 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 91 

3. HEALTH EFFECTS 

A centrilobular degenerative change occurred in the liver of male B6C3F1 mice exposed to ethylene 

glycol in estimated dietary doses of 6,450 or 12,900 mg/kg/day for 13 weeks (Melnick 1984; NTP 1993). 

This effect was characterized by the accumulation of a non-birefringent eosinophilic hyaline material in 

the cytoplasm of hepatocytes adjacent to or close to the central veins, and was not observed in females 

similarly exposed to ≤16,000 mg/kg/day (Melnick 1984; NTP 1993). No liver lesions or changes in liver 

weight were observed in CD-1 mice exposed to ≤2,500 mg/kg/day by gavage for 17 days (Harris et al. 

1992) or ≤2,826 mg/kg/day in the diet for one or two generations (Bolon et al. 1997; Morrissey et al. 

1989; NTP 1986), Wistar rats exposed to ≤2,000 mg/kg/day by gavage for 33 days (Schladt et al. 1998) or 

≤1,128 mg/kg/day in the diet for 16 weeks (Gaunt et al. 1974), F344 rats exposed to ≤10,000 mg/kg/day 

in the diet for 13 weeks (Melnick 1984), or Sprague-Dawley rats exposed to ≤5,744 mg/kg/day in 

drinking water for 90 days (Robinson et al. 1990). There were no effects on serum alanine 

aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AP), lactate 

dehydrogenase (LDH), cholesterol, and/or bilirubin in the 33- and 90-day studies in rats (Robinson et al. 

1990; Schladt et al. 1998); clinical chemistry was not evaluated in the other intermediate-duration studies. 

A 2-year study of ethylene glycol in B6C3F1 mice found significantly increased incidences of 

centrilobular hepatocyte hyaline degeneration in males at estimated dietary doses of 3,000 and 

6,000 mg/kg/day (45 and 67% compared to 0% in controls) and females at 12,000 mg/kg/day (52% 

compared to 0% in controls) (NTP 1993). The lesions appeared similar to the hyaline degeneration in the 

13-week study by the same investigators (Melnick 1984; NTP 1993) and consisted of cytoplasmic 

accumulations of non-birefringent, eosinophilic, granular to globular material resembling erythrocytes in 

size, shape, and tinctorial properties. Severity did not increase with dose. In another chronic study, 

CD-1 mice and F344 rats of both sexes were exposed to doses as high as 1,000 mg/kg/day in the diet for 

up to 2 years (DePass et al. 1986a; Woodside 1982). There were no effects on liver weight or 

histopathology in mice of either sex or male rats, or on serum parameters of liver function in male or 

female rats (not evaluated in mice). The female F344 rats had significantly increased incidences of slight 

liver fatty metamorphosis at ≥200 mg/kg/day and liver mononuclear cell infiltrates at 1,000 mg/kg/day; 

the incidences of slight fatty metamorphosis were 13% (34/256), 12% (16/129), 22% (27/125), and 27% 

(35/128) at 0, 40, 200, and 1,000 mg/kg/day, respectively. The biological significance of these minor 

hepatic lesions is questionable because of the lack of effects on liver weight and liver function measures, 

even at the highest dose. A 2-year dietary study in Sprague-Dawley rats found no effects on liver weight 

or histopathology in males at ≤375 mg/kg/day (higher doses caused early mortality) or females at 

≤3,000 mg/kg/day (Blood 1965). 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 92 

3. HEALTH EFFECTS 

Renal Effects. Adverse renal effects after ethylene glycol ingestion in humans can be observed during 

the third stage of ethylene glycol toxicity 24–72 hours after acute exposure (Davis et al. 1997; Hess et al. 

2004). The hallmark of renal toxicity is the presence of birefringent calcium oxalate monohydrate 

crystals deposited in renal tubules and their presence in urine after ingestion of relatively high amounts of 

ethylene glycol (CDC 1987; Baum et al. 2000; Blakeley et al. 1993; Boyer et al. 2001; Chung and Tuso 

1989; Davis et al. 1997; Factor and Lava 1987; Froberg et al. 2006; Godolphin et al. 1980; Hantson et al. 

2002; Heckerling 1987; Huhn and Rosenberg 1995; Leth and Gregersen 2005; Lovrić et al. 2007; Olivero 

1993; Parry and Wallach 1974; Rasic et al. 1999; Rothman et al. 1986; Siew et al. 1975a; Takayesu et al. 

2006; Underwood and Bennett 1973). In addition to birefringent oxalate crystals in the tubular lumens, 

other signs of nephrotoxicity can include tubular cell degeneration and necrosis and tubular interstitial 

inflammation (Davis et al. 1997; Factor and Lava 1987; Froberg et al. 2006; Hantson et al. 2002; Rasic et 

al. 1999; Tobe et al. 2002). In a case study of a 38-year-old female who consumed 240 mL of antifreeze 

(3,454 mg ethylene glycol/kg/day), crystalluria was not present upon hospital admission (about 12 hours 

after ingestion). Within 5 hours, excretion of calcium oxalate dihydrate crystals was evident, although 

monohydrate crystals became the primary form in the urine thereafter (2–3 hours) (Jacobsen et al. 1988). 

In the course of ethylene glycol intoxication, serum creatinine (Factor and Lava 1987; Spillane et al. 

1991) and serum blood urea nitrogen (BUN) (Chung and Tuso 1989; Factor and Lava 1987) levels may 

be increased. If untreated, the degree of renal damage caused by high doses of ethylene glycol progresses 

and leads to hematuria (Baum et al. 2000; CDC 1987; Davis et al. 1997; Rothman et al. 1986; Underwood 

and Bennett 1973), proteinuria (Davis et al. 1997; Rothman et al. 1986), decreased renal function, 

oliguria, anuria (Davis et al. 1997; Mallya et al. 1986; Parry and Wallach 1974; Spillane et al. 1991; 

Woolf et al. 1992; Zeiss et al. 1989), and ultimately renal failure (Chung and Tuso 1989; Gordon and 

Hunter 1982; Jacobsen et al. 1984; Johnson et al. 1999; Mallya et al. 1986; Takayesu et al. 2006). These 

changes in the kidney are linked to acute tubular necrosis (Factor and Lava 1987), but normal or near 

normal renal function can return with adequate supportive therapy (see Section 3.11, Methods for 

Reducing Toxic Effects). 

In acute-duration studies in rats, kidney effects occurred at doses as low as 1,250 mg/kg/day by gavage 

and 1,400 mg/kg/day in drinking water. Renal tubular dilation and regeneration were increased in female 

Sprague-Dawley rats that were exposed to 1,250 or 2,250 mg/kg/day ethylene glycol by gavage on Gd 6– 

20 and examined on postnatal day (Pnd) 1 (NTP 1988). Increased relative and absolute kidney weights, 

but no renal histopathology, occurred in female CD rats exposed to 2,500 mg/kg/day by gavage on Gd 6– 

15 and examined on Gd 21 (Neeper-Bradley 1990; Neeper-Bradley et al. 1995). In a 10-day drinking 

water systemic toxicity study, the incidence and severity of renal lesions were significantly increased in 
 

 

 

 

 

 

 

 

 

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male Sprague-Dawley rats exposed to 2,615 and 5,270 mg/kg/day, but not at doses ≤1,343 mg/kg/day; 

lesions included tubular dilation, degeneration, necrosis, and intratubular calcium oxalate crystals 

(Robinson et al. 1990). Exposure to 1,400 mg/kg/day in the drinking water for 15–29 days caused renal 

tubular oxalate deposits, but apparently no nephrosis, in male Sprague-Dawley rats (Khan et al. 1993). 

Mice that were administered doses ≤1,000 mg/kg by gavage for 4 days had no histopathological changes 

in the kidneys (Hong et al. 1988). Renal toxicity occurred in female New Zealand white rabbits that were 

exposed to 2,000 mg/kg/day by gavage on Gd 6–19 and examined on Gd 30; lesions that included tubule 

dilatation and regeneration, epithelial necrosis, and intraluminal oxalate crystal deposition were increased 

at this dose level, but not at doses ≤1,000 mg/kg/day (Tyl et al. 1993). 

Limited data are available on acute renal effects in other species. A single oral dose of 4,440 mg/kg in 

cats (Penumarthy and Oehme 1975) or 4,880 or 10,743 mg/kg in dogs (Beckett and Shields 1971; Grauer 

et al. 1987) caused kidney damage leading to oliguria and renal failure. Dogs administered a single dose 

of 10,600 mg/kg ethylene glycol as antifreeze or as reagent-grade ethylene glycol in feed exhibited 

polyuria, azotemia, and renal failure (Dial et al. 1994). Serum BUN and creatinine were not increased in 

two dogs given a single gavage dose of approximately 1,000 mg/kg/day, suggesting that renal function 

was not altered (Hewlett et al. 1989). Histopathological changes in the kidneys of dogs given a single 

3,300 mg/kg gavage dose of ethylene glycol first appeared at 12 hours post-dosing; effects were most 

common in the proximal convoluted tubules and included interstitial edema, tubular dilation, and cellular 

degeneration and necrosis (Smith et al. 1990). Crystal formation was observed mainly within tubular 

lumina (most frequently in the proximal convoluted tubules), but generally not before 24 hours postdosing. In male macaque monkeys exposed to ethylene glycol in drinking water, five of seven animals 

receiving doses ranging from 1,665 to 146,520 mg/kg/day for 6–13 days had calcium oxalate crystals and 

evidence of necrosis in the kidneys (Roberts and Seibold 1969). 

The renal effects of intermediate-duration oral exposure to ethylene glycol are well characterized in a 

number of studies in rats and mice (Cruzan et al. 2004; Gaunt et al. 1974; Melnick 1984; NTP 1993; 

Robinson et al. 1990). As summarized below, the results of these studies indicate that renal toxicity 

varies with sex, species, and strain, with males more sensitive than females, rats more sensitive than mice, 

and Wistar rats more sensitive than other strains of rats. 

In a 90-day drinking water study with Sprague-Dawley rats (Robinson et al. 1990), incidences of renal 

lesions were significantly increased in males at ≥947 mg/kg/day and females at ≥3,087 mg/kg/day. Males 

showed a greater number and severity of lesions than females; lesions included tubular dilation and 
 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 94 

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degeneration, acute and subacute inflammation, calcium oxalate crystals in tubules and pelvis epithelium, 

dilation of urinary pelvis, and hyperplasia and degeneration of pelvis epithelium. The male rats also had 

increases in relative kidney weight and serum creatinine at ≥947mg/kg/day and BUN at 

3,134 mg/kg/day. A 13-week dietary study in F344 rats (Melnick 1984) found renal effects that included 

increased relative kidney weight at ≥2,500 mg/kg/day in males and ≥5,000 mg/kg/day in females, 

increased BUN and serum creatinine in males at ≥2,500 mg/kg/day, and histopathology in males 

≥2,500 mg/kg/day and females at 10,000 mg/kg/day. The lesions were more severe in the males (e.g., 

dilation, necrosis, fibrosis, and crystal deposition in renal tubules) than in the females (e.g., inflammation 

and vacuolation without crystal deposition). The NOAELs for renal toxicity in this study were 

1,250 mg/kg/day in males and 2,500 mg/kg/day in females. 

In a 16-week dietary study in Wistar rats (Gaunt et al. 1974), renal findings in males included no effects 

at 71 mg/kg/day, increased incidences of kidney lesions at ≥180 mg/kg/day, and oxalic acid crystals in 

urine, increased absolute kidney weight, increased urine volume, and decreased urine specific gravity at 

715 mg/kg/day. The lesions ranged from degenerative changes in individual nephrons with occasional 

oxalate crystals to generalized tubular damage with heavy crystal deposition. At the 0, 35, 71, 180, and 

715 mg/kg/day dose levels for the male rats in this study, the overall incidence of renal tubular damage 

was 0/15, 1/15, 1/15, 4/15, and 15/15, respectively. The only effect observed in females was a nonstatistically significant increase in kidney lesions at 1,128 mg/kg/day, the highest tested dose. Limitations 

of this study include questionable animal care and dose levels that were not constant. Most of the rats 

showed evidence of respiratory infection (pneumonia) and infectious salivary adenitis, either of which 

could have confounded the results. The dose levels decreased throughout the exposure period because the 

amount of ethylene glycol in the diet was not adjusted for changing food consumption and body weight. 

For example, at the apparent LOAEL of 180 mg/kg/day, the rats were exposed to approximately 

300 mg/kg/day for the first 2 weeks of the study; this level is above the threshold for renal toxicity in 

male Wistar rats shown in a 12-month study (Corley et al. 2008). Further, the rats were housed in groups 

of five, such that consumption of individual rats among the groups likely varied. 

In another 16-week dietary study (Cruzan et al. 2004), male Wistar and male F344 rats were exposed to 

dose levels of 0, 50, 150, 500, or 1,000 mg/kg/day. Effects included calcium oxalate crystals in the urine 

of both strains of rats at ≥150 mg/kg/day and increased absolute and relative kidney weights, increased 

water intake, increased urine volume, and decreased urine specific gravity at ≥500mg/kg/day in Wistar 

rats and 1,000 mg/kg/day in F344 rats. No treatment-related increases in alpha 2-μ-globulin were 

observed in the kidneys of either strain of rats. No histological effects occurred in the kidneys of either 
 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 95 

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strain of rats at 50 or 150 mg/kg/day. At higher doses, histopathological findings included calcium 

oxalate crystal deposition in the renal tubules with associated nephropathy in all Wistar rats (10/dose) at 

≥500 mg/kg/day. Histological findings in the F344 rats included crystals in the tubules without 

nephropathy in 6/10 animals at 500 mg/kg/day, and crystal nephropathy in 1/10 animals at 500 mg/kg/day 

and 10/10 animals at 1,000 mg/kg/day. The severity of the crystal nephropathy in the Wistar rats at 

500 mg/kg/day was approximately equivalent to that in the F344 rats at 1,000 mg/kg/day. Although the 

male Wistar rats were more sensitive than the male F344 rats, the LOAEL for kidney toxicity was 

500 mg/kg/day in both strains. The NOAEL in both strains of rats is 150 mg/kg/day because the only 

effect at this dose, crystalluria, reflects a detoxification process and is not adverse in the absence of 

crystal deposition in the renal tubule epithelium and associated histopathology. 

Information on the intermediate-duration renal toxicity of ethylene glycol is also available in mice. In a 

13-week dietary study in B6C3F1 mice, effects were observed in the kidneys of males at 

≥6,450 mg/kg/day (minimal to mild tubule dilation, cytoplasmic vacuolation, and regenerative 

hyperplasia, without tubular oxalate crystal deposition), with no effects on kidney histology or urinalysis 

in females at doses ≤16,000 mg/kg/day (Melnick 1984; NTP 1993). No histopathological changes were 

observed in the kidneys of male CD-1 mice that were administered doses as high as 2,500 mg/kg/day by 

gavage for 17 days (Harris et al. 1992). Kidney weight and histology were evaluated in F0 and F1 parental 

male and female CD-1 mice that were exposed to 2,826 mg/kg/day in the drinking water in a twogeneration reproduction study (Bolon et al. 1997; Morrissey et al. 1989; NTP 1986). The exposure period 

of both generations included 14 weeks of cohabitation through gestation and lactation. Kidney lesions 

occurred in 60% of the F0 male mice; the lesions included tubular degeneration, dilation, and 

regeneration, as well as a low incidence of oxalate crystal deposition (3/20 treated vs. 0/21 controls). 

There was no effect on kidney weight in the F0 males or on kidney weight or histology in the F0 females 

or F1 males or females. 

A 1-year study in rats (Corley et al. 2008) and 2-year studies in rats (Blood 1965; DePass et al. 1986a) 

and mice (DePass et al. 1986a; NTP 1993) provide information on chronic renal toxicity of ethylene 

glycol. Males were more sensitive than females, rats were more sensitive than mice, and Wistar rats 

appear to be the most sensitive strain to ethylene glycol nephrotoxicity. 

Male Wistar rats were exposed to ethylene glycol in dietary doses of 0, 50, 150, 300, or 400 mg/kg/day 

for 12 months (Corley et al. 2008). Decreased urinary pH and increased urinary oxalate crystals occurred 

at all dose levels; these effects were not considered adverse, but rather normal metabolic/physiological 
 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 96 

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consequences of ethylene glycol exposure. Effects at ≥300 mg/kg/day included increased water

consumption with corresponding increased urine volume and decreased urine specific gravity, increased 

absolute and relative kidney weights, and gross and histopathological changes in the kidneys and bladder. 

Gross pathology included calculi, dilatation, and hemorrhage in the bladder at ≥300 mg/kg/day and 

calculi and dilatation in the renal pelvis and ureter at 400 mg/kg/day. Renal histopathology occurred in 

the majority of animals at 300 mg/kg/day and in all animals at 400 mg/kg/day; lesions included 

crystalluria-related nephropathy, tubule dilatation, birefringent crystals (particularly in the pelvic fornix), 

pelvic dilatation, and transitional cell hyperplasia. Incidences of crystal nephropathy, the most prevalent 

lesion, were 0/14, 0/15, 0/15, 12/13, and 10/10 at 0, 50, 150, 300, and 400 mg/kg/day, respectively. 

Histopathological changes in the bladder occurred in the majority of animals at ≥300 mg/kg/day; the basic

change was transitional cell hyperplasia, progressing to acute inflammation and hemorrhage in severe 

cases. Inflammation and hemorrhage of the bladder wall apparently contributed to mortality at 

≥300 mg/kg/day. There were no treatment-related effects on renal clearance of oxalate or inulin. Kidney 

concentrations of glycolate and oxalate were unchanged at 50 and 150 mg/kg/day, but clear nonlinear 

increases in both of these metabolites occurred at ≥300 mg/kg/day, indicating that the accumulation of

calcium oxalate in the kidneys correlated with the appearance of renal toxicity. A NOAEL of 

150 mg/kg/day and a LOAEL of 300 mg/kg/day were identified in male Wistar rats based on 

histopathology in the kidneys (crystal nephropathy) and bladder (inflammation and hemorrhage). 

In Sprague-Dawley rats that were fed ethylene glycol for 2 years, effects included increased water 

consumption, proteinuria, and mortality in males at ≥750 mg/kg/day and females at 3,000 mg/kg/day. 

Incidences of calcification (oxalate crystal deposition) in the kidneys were increased in both sexes at 

≥750 mg/kg/day, and oxalate-containing calculi were increased in males at ≥750 mg/kg/day and females 

at 3,000 mg/kg/day. The incidences of oxalate crystal deposition in the males were 0/7, 0/12, 0/10, 4/10, 

7/7, and 15/15 at 0, 75, 150, 375, 750 and 3,000 mg/kg/day; the increase at 375 mg/kg/day was not 

statistically significant. The report implied, but did not adequately document, that many of the animals 

with crystal deposition in the renal tubules also had degenerative changes (mainly cytoplasmic 

vacuolation) in the tubular epithelium. Due to the insufficiently reported histopathology findings and lack 

of a clear (statistically significant) increase in oxalate crystal deposition at 375 mg/kg/day due to small 

numbers of animals, this study provides limited evidence that 375 mg/kg/day was a chronic LOAEL for 

kidney toxicity in male Sprague-Dawley rats. 

F344 rats (130/sex/dose) were fed ethylene glycol in the dietary concentrations that yielded reported 

approximate doses of 0, 40, 200, or 1,000 mg/kg/day for up to 2 years (DePass et al. 1986a). No 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 97 

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treatment-related or statistically significant changes occurred in the male rats at 40 or 200 mg/kg/day. A 

number of renal effects were observed in the 1,000 mg/kg/day males after 12 months (subsequent 

sacrifices at this dose level were precluded by early mortality), including increased water consumption 

and urine volume, decreased urine specific gravity and pH, increased urinary calcium oxalate crystals, 

increased BUN and serum creatinine. Increases in absolute and relative kidney weights and incidences of 

kidney lesions were increased at 1,000 mg/kg/day at 6 and 12 months. At 6 months, incidences of the 

following renal lesions were significantly increased in the 1,000 mg/kg/day males: calcium oxalate 

crystalluria, tubular hyperplasia, tubular dilation, and peritubular nephritis. All of the 1,000 mg/kg/day 

males that were sacrificed at 12 months had calcium oxalate crystalluria as well as multiple severe renal 

lesions that included tubular dilation, proteinosis and hyperplasia, glomerular shrinkage, and/or chronic 

interstitial nephritis. Most of the 1,000 mg/kg/day males that died during the study or were sacrificed 

when moribund had oxalate nephrosis, which was the primary cause of death, and hydronephrosis. The 

female rats were less sensitive to kidney toxicity than the males as shown by renal effects that were 

limited to increases in kidney weight and calcium oxalate crystals and uric acid crystals in the urine at 

1,000 mg/kg/day; no histopathological changes occurred in the kidneys. A NOAEL of 200 mg/kg/day 

and serious LOAEL of 1,000 mg/kg/day were identified in male F344 rats based on kidney toxicity 

(oxalate nephrosis)-induced mortality. 

CD-1 mice (80/sex/dose) were also fed ethylene glycol in the dietary concentrations that yielded reported 

approximate doses of 0, 40, 200, or 1,000 mg/kg/day for up to 2 years (DePass et al. 1986a). No 

treatment-related kidney histopathology occurred in either sex; water consumption, clinical chemistry, 

urinalysis, and organ weight were not evaluated as in the companion study in rats. B6C3F1 mice 

(60/sex/dose) were exposed to ethylene glycol in the diet for up to 2 years at estimated doses as high as 

6,000 mg/kg/day in males and 12,000 mg/kg/day in females (NTP 1993). Histopathological evaluations 

of the kidneys showed effects that were limited to small numbers of oxalate-like crystals and/or calculi 

were noted in the renal tubules, urethrae, and urinary bladder in a few males at 6,000 mg/kg/day. 

Endocrine Effects. Histological examinations of endocrine organs in acute-, intermediate- and 

chronic-duration studies of ethylene glycol showed no effects in rats or mice. As indicated in Table 3-2, 

the evaluations included the adrenals, pancreas, pituitary, thyroid, and/or parathyroids in Sprague-Dawley 

rats exposed to ≤7,327 mg/kg/day in drinking water for 10 days or ≤5,744 mg/kg/day in drinking water 

for 90 days (Robinson et al. 1990), Wistar rats exposed to ≤2,000mg/kg/day by gavage for 4 weeks 

(Schladt et al. 1998), F344 rats exposed to ≤10,000 mg/kg/day in the diet for 13 weeks (Melnick 1984), 

Wistar rats exposed to ≤1,128 mg/kg/day in the diet for 16 weeks (Gaunt et al. 1974), Sprague-Dawley 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 98 

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rats exposed to ≤3,000 mg/kg/day in the diet for 2 years (Blood 1965), F344 rats exposed to 

1,000 mg/kg/day in the diet for 1 year (DePass et al. 1986a; Woodside 1982), B6C3F1 mice exposed to 

≤250 mg/kg/day by gavage for 4 days (Hong et al. 1988), B6C3F1 mice exposed to ≤16,000 mg/kg/day in 

the diet for 13 weeks or ≤12,000 mg/kg/day in the diet for 2 years (Melnick 1984; NTP 1993), or 

CD-1 mice exposed to ≤1,000 mg/kg/day in the diet for 2 years (DePass et al. 1986a; Woodside 1982). 

None of these studies included assessments of endocrine function. 

Dermal Effects. Histological examinations of the skin showed no effects in Sprague-Dawley rats 

exposed to ≤7,327 mg/kg/day in drinking water for 10 days or ≤5,744 mg/kg/day in drinking water for 

90 days (Robinson et al. 1990), F344 rats exposed to 1,000 mg/kg/day in the diet for 1 year (DePass et al. 

1986a; Woodside 1982), B6C3F1 mice exposed to ≤12,000 mg/kg/day in the diet for 2 years (Melnick 

1984; NTP 1993), or CD-1 mice exposed to ≤1,000 mg/kg/day in the diet for 2 years (DePass et al. 

1986a; Woodside 1982). 

Ocular Effects. Histological examinations of the eyes showed no effects in Wistar rats exposed to 

≤1,128 mg/kg/day in the diet for 16 weeks (Gaunt et al. 1974), or in F344 rats or CD-1 mice exposed to 

≤1,000 mg/kg/day in the diet for 1–2 years (DePass et al. 1986a; Woodside 1982). 

Body Weight Effects. In an acute-duration study, male Sprague-Dawley rats exposed to 

5,279 mg/kg/day ethylene glycol in the diet for 10 days experienced 13% body weight loss; no effect 

occurred in females at doses as high as 7,327 mg/kg/day (Robinson et al. 1990). Administration of 

ethylene glycol by gavage during gestation (Gd 6–15 or 6–20) caused 17–31% decreases in maternal 

body weight gain in CD and Sprague-Dawley rats exposed to 1,250–2,500 mg/kg/day and B6C3F1 mice 

exposed to 1,500 mg/kg/day (Marr et al. 1992; Neeper-Bradley 1990, Neeper-Bradley et al. 1995; NTP 

1988; Price et al. 1985). Body weight gain corrected for gravid uterine weight was generally similar to 

controls, indicating that intrauterine loss was a significant contributor to the reduced maternal weight gain 

during pregnancy. New Zealand white rabbits showed no changes in maternal body weight after gavage 

exposure to 2,000 mg/kg/day ethylene glycol on Gd 6–19 (Tyl et al. 1993). 

In intermediate-duration studies, body weight gain was 9–30% lower than controls in Wistar rats exposed 

to 500 mg/kg/day in the diet for 16 weeks, Sprague-Dawley rats exposed to 750 mg/kg/day in the diet or 

3,134 mg/kg/day in drinking water for 90–100 days, and F344 rats exposed to 2,500 mg/kg/day in the diet 

for 13 weeks (Blood 1965; Cruzan et al. 2004; Melnick 1984; NTP 1993; Robinson et al. 1990). No 

adverse effects on body weight occurred in CD-1 mice exposed to 2,500 mg/kg/day by gavage for 17 days 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 99 

3. HEALTH EFFECTS 

(Harris et al. 1992) or B6C3F1 mice exposed 16,000 mg/kg/day in the diet for 13 weeks (Melnick 1984; 

NTP 1993). 

Chronic (2-year) dietary studies of ethylene glycol found decreased body weight gain (15% less than 

controls) in male F344 rats at 1,000 mg/kg/day, but not in male F344 or Sprague-Dawley rats at 200– 

375 mg/kg/day (Blood 1965; DePass et al. 1986b); decreased body weight gain in female SpragueDawley rats at 3,000 mg/kg/day, but not in female Sprague-Dawley or F344 rats at 750–1,000 mg/kg/day 

(Blood 1965; DePass et al. 1986b); and no effects on body weight in CD-1 or B6C3F1 mice at 1,000– 

12,000 mg/kg/day (DePass et al. 1986a; Melnick 1984; NTP 1993; Woodside 1982). In a 12-month 

dietary study in male Wistar rats, body weight gain was reduced 8.4% on day 365 at 300 mg/kg/day and 

31.3% on day 197 at 400 mg/kg/day (Corley et al. 2008). 

Metabolic Effects. One of the major adverse effects following acute oral exposure of humans to 

ethylene glycol involves metabolic changes. These changes occur as early as 12 hours after ethylene 

glycol exposure. Ethylene glycol intoxication is accompanied by metabolic acidosis which is manifested 

by decreased pH and bicarbonate content of serum and other bodily fluids caused by accumulation of 

excess glycolic acid (Amathieu et al. 2006; CDC 1987; Berger and Ayyar 1981; Blakeley et al. 1993; 

Cheng et al. 1987; Chung and Tuso 1989; Gordon and Hunter 1982; Heckerling 1987; Jacobsen et al. 

1988; Parry and Wallach 1974; Pellegrino et al. 2006; Siew et al. 1975a; Spillane et al. 1991; Takayesu et 

al. 2006; Woolf et al. 1992; Zeiss et al. 1989). There is an inverse relationship between the decreasing 

plasma pH and increasing plasma glycolic acid concentrations (Clay and Murphy 1977). The normal 

level of bicarbonate of 24 mmol/L can be depleted in cases of severe ethylene glycol intoxication to reach 

concentrations as low as 2 mmol/L (Jacobsen et al. 1984). This decrease in base concentration indicates 

that a similar quantity of acid has to be present to achieve such a depletion. Glycolic acid is the only 

acidic metabolite present in such quantities. Humans highly intoxicated with ethylene glycol had 

glycolate concentrations of 17–29 and <1 mmol of glyoxylate and oxalate, respectively (Jacobsen et al. 

1984). Similar observations were made in animals. Metabolic acidosis due to glycolate accumulation 

was observed after acute oral exposure of dogs to 1,000–1,360 mg/kg of ethylene glycol (Hewlett et al. 

1989) and of rats to 1,000 mg/kg (Marshall 1982). These results indicate that glycolic acid is the major 

toxic metabolite causing metabolic acidosis, and that its high serum levels are likely responsible for 

systemic toxicity observed after ethylene glycol exposure. 

Other characteristic metabolic effects of ethylene glycol poisoning are increased serum anion gap, 

increased osmolal gap, and hypocalcemia. Serum anion gap is calculated from concentrations of sodium, 
 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 100 

3. HEALTH EFFECTS 

chloride, and bicarbonate, is normally 12–16 mM, and is typically elevated after ethylene glycol ingestion 

due to increases in unmeasured metabolite anions (mainly glycolate) (Amathieu et al. 2006; Chung and 

Tuso 1989; Curtin et al. 1992; Davis et al. 1997; Factor and Lava 1987; Heckerling 1987; Hess et al. 

2004; Jacobsen et al. 1984; Pellegrino et al. 2006; Spillane et al. 1991; Takayesu et al. 2006; Taylor et al. 

1997; Walder and Tyler 1994; Zeiss et al. 1989). Osmolal gap represents the difference between the 

measured and calculated osmolalities and is also typically elevated during ethylene glycol intoxication 

(Baum et al. 2000; Boyer et al. 2001; Curtin et al. 1992; Davis et al. 1997; Taylor et al. 1997; Walder and 

Tyler 1994). The normal value for osmolal gap in humans is 10–15 mOsm/kg water (Egbert and 

Abraham 1999; Leth and Gregersen 2005; Scalley et al. 2002). Each 16 mM (100 mg/dL) increment in 

ethylene glycol concentration contributes to about 16 mOsm/kg water (Hess et al. 2004). Amounts of 

ethylene glycol causing these in humans effects have ranged from 1,628 to 12,840 mg/kg/day (Chung and 

Tuso 1989; Heckerling 1987; Spillane et al. 1991). Dogs receiving a single dose of 10,600 mg/kg 

ethylene glycol as antifreeze or as reagent grade ethylene glycol in feed exhibited metabolic acidosis and 

hyperosmolality (Dial et al. 1994). Although a high anion gap metabolic acidosis and an increased 

osmolal gap are common metabolic changes associated with ethylene glycol intoxication, clinically 

significant ingestions are possible without substantially elevating either of these parameters (Davis et al. 

1997; Huhn and Rosenberg 1995; Moossavi et al. 2003; Pellegrino et al. 2006; Taylor et al. 1997). One 

case report presented a patient who developed recurrent severe anion gap metabolic acidosis with no 

osmolar gap consequent to episodic ethylene glycol ingestion (Moossavi et al. 2003). Hypocalcemia is 

occasionally reported and occurs when oxalate chelates with calcium ions forming insoluble calcium 

oxalate monohydrate crystals (Davis et al. 1997; Takayesu et al. 2006). This affects the overall ion 

concentration and can lead to an imbalance of divalent ion concentrations (Zeiss et al. 1989). 

3.2.2.3 Immunological and Lymphoreticular Effects 

No specific information was located regarding immunological and lymphoreticular effects in humans 

orally exposed to ethylene glycol. Moderate leukocytosis has been observed in some cases of acute oral 

poisoning (Davis et al. 1997; Parry and Wallach 1974; Reddy et al. 2007; Verrilli et al. 1987). 

Immune responses were investigated in male CBA mice that were treated with a single 12,000 mg/kg 

dose of ethylene glycol by gavage (Zabrodskii and Germanchuk 2000; Zabrodskii et al. 2003). Exposurerelated effects were observed on all tested end points; results included increased mortality from 

Escherichia coli-induced infection (peritonitis), decreased number of spleen colony-forming units, 

decreased numbers of antibody-producing cells in spleen to sheep erythrocytes (T cell-dependent antigen) 
 

 

 

 

 

 

 

ETHYLENE GLYCOL 101 

3. HEALTH EFFECTS 

and Vi-agglutinin (T cell-independent antigen), decreased activity of natural killer cells, decreased 

antibody-dependent cytotoxicity of splenocytes to sheep erythrocytes, and decreased delayed-type 

hypersensitivity to sheep erythrocytes. 

No information is available on immune function in animals following intermediate- or chronic-duration 

exposure to ethylene glycol. 

Histological examinations of immune and lymphoreticular system tissues in acute-, intermediate-, and 

chronic-duration studies of ethylene glycol showed no effects in rats or mice. As indicated in Table 3-2, 

the evaluations included spleen, lymph nodes, and/or thymus in Wistar rats exposed to ≤2,000 mg/kg/day 

by gavage for 4 weeks (Schladt et al. 1998), Sprague-Dawley rats exposed to ≤7,327 mg/kg/day in 

drinking water for 10 days or ≤5,744 mg/kg/day in drinking water for 90 days (Robinson et al. 1990), 

Wistar rats exposed to ≤1,128 mg/kg/day in the diet for 16 weeks (Gaunt et al. 1974), F344 rats exposed 

to ≤10,000 mg/kg/day in the diet for 13 weeks (Melnick 1984), F344 rats exposed to 1,000 mg/kg/day in 

the diet for 1 year (DePass et al. 1986a; Woodside 1982), Sprague-Dawley rats exposed to 

≤3,000 mg/kg/day in the diet for 2 years (Blood 1965), B6C3F1 mice exposed to ≤250 mg/kg/day by 

gavage for 4 days (Hong et al. 1988), B6C3F1 mice exposed to ≤16,000 mg/kg/day in the diet for 

13 weeks or ≤12,000 mg/kg/day in the diet for 2 years (Melnick 1984; NTP 1993), or CD-1 mice exposed 

to ≤1,000 mg/kg/day in the diet for 2 years (DePass et al. 1986a; Woodside 1982). 

Leukocyte counts were generally unaffected in the acute-, intermediate- and chronic-duration studies of 

ethylene glycol cited above. Exceptions included statistically significant decreased total leukocyte counts 

in female Sprague-Dawley rats exposed to 7,327 mg/kg/day for 10 days (34.8% less than controls) or 

597–5,744 mg/kg/day for 90 days (30–50% less than controls) (Robinson et al. 1990), and significantly 

increased neutrophil count (38% higher than controls) in male F344 rats exposed to 1,000 mg/kg/day for 

1 year (DePass et al. 1986a). 

The highest NOAEL values and all reliable LOAEL values for immunological and lymphoreticular 

effects in rats after intermediate-duration oral exposure to ethylene glycol are reported in Table 3-2 and 

plotted in Figure 3-2. 
 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 102 

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3.2.2.4 Neurological Effects 

Adverse neurological reactions are among the first symptoms to appear in humans after ethylene glycol 

ingestion. These early neurotoxic effects are also the only symptoms attributed to unmetabolized 

ethylene glycol. Together with metabolic changes, they occur during the period of 30 minutes to 12 hours 

after exposure and are considered to be part of the first stage in ethylene glycol intoxication (Davis et al. 

1997; Hess et al. 2004; Robinson and McCoy 1989; Vale 1979). In cases of acute intoxication, in which 

a large amount of ethylene glycol is ingested over a very short time period, there is a progression of 

neurological manifestations which, if not treated, may lead to generalized seizures and coma (Chung and 

Tuso 1989; Froberg et al. 2006; Hantson et al. 2002; Jobard et al. 1996; Leth and Gregersen 2005; 

Olivero 1993; Siew et al. 1975a; Takayesu et al. 2006; Zeiss et al. 1989). Ataxia, slurred speech, 

confusion, and somnolence are common during the initial phase of ethylene glycol intoxication (Boyer et 

al. 2001; Buell et al. 1998; CDC 1987; Parry and Wallach 1974; Reddy et al. 2007; Takayesu et al. 2006; 

Tobe et al. 2002; Zeiss et al. 1989), as are irritation, restlessness, and disorientation (Cheng et al. 1987; 

Factor and Lava 1987; Gordon and Hunter 1982; Rothman et al. 1986; Woolf et al. 1992), and 

semiconsciousness and unresponsiveness (Blakeley et al. 1993; Chung and Tuso 1989; Heckerling 1987; 

Spillane et al. 1991; Underwood and Bennett 1973). In an unusual case of ethylene glycol poisoning, 

initial neurological symptoms of confusion, slurred speech, and somnolence were followed by the 

development of deafness, dysphagia, and dysarthria after 7 days and full paralysis after 12 days (Tobe et 

al. 2002). The patient was completely unresponsive to any stimulus, all brainstem reflexes were absent, 

clinical neurophysiological examination showed a severe axonal polyneuropathy, and sural nerve biopsy 

findings showed severe axonal degeneration and oxalate deposits. 

Cerebral edema and crystalline deposits of calcium oxalate in the walls of small blood vessels in the brain 

were found at autopsy in people who died after acute ethylene glycol ingestion (Friedman et al. 1962; 

Froberg et al. 2006; Hantson et al. 2002; Leth and Gregersen 2005; Zeiss et al. 1989). In one case of fatal 

ethylene glycol poisoning, the development of rapid cerebral edema was documented by computed 

tomography (CT) scan and was accompanied by definitive evidence of calcium oxalate crystals within 

walls of central nervous system blood vessels, with associated inflammation and edema (Froberg et al. 

2006). In a case of nonfatal poisoning, CT showed a marked edema and leukoencephalopathy of both 

cerebral hemispheres on the tenth day after ingestion that conformed to a toxic or inflammatory 

encephalopathy (Chung and Tuso 1989). The cerebral edema decreased drastically during the next 

20 days, although some residual temporal lobe dysfunctions and auditory verbal agnosia developed. 

Unusual brain findings in other cases of ethylene glycol poisoning included bilateral pallidal hemorrhage 
 

 

 

 

 

 

 

ETHYLENE GLYCOL 103 

3. HEALTH EFFECTS 

(Caparros-Lefebvre et al. 2005) and acute hemorrhagic necrosis of the basal ganglia that resulted in acute 

Parkinson’s syndrome (Reddy et al. 2007). 

Effects on cranial nerves appear late (generally 5–20 days post-ingestion), are relatively rare, and 

according to some investigators constitute a fourth, late cerebral phase in ethylene glycol intoxication 

(Chung and Tuso 1989; Gardner et al. 2004; Lewis et al. 1997). Clinical manifestations of the cranial 

neuropathy commonly involve lower motor neurons of the facial and bulbar nerves and are reversible 

over many months. In one case, facial paralysis and bilateral optic nerve dysfunction were noted in a 

patient 13 days after ethylene glycol ingestion (Factor and Lava 1987). Delay in treatment may have 

contributed to the development of these symptoms; the patient was not treated until 3 days after ingesting 

ethylene glycol. Severe cranial nerve dysfunction including nerves VII, IX, and X was noted in a man 

5 days after he ingested 12,840 mg/kg of ethylene glycol (Spillane et al. 1991). In another case of 

ethylene glycol poisoning, bilateral facial paralysis and peripheral neurosensory hearing loss were 

observed in a patient 18 days after ingestion of 2,714 mg/kg of ethylene glycol; this effect was only 

partially reversible (Mallya et al. 1986). Bilateral paralysis of cranial nerve VII, as well as bilateral 

dysfunction of cranial nerves II, V, VIII, IX, X, and XII, developed in a woman 10–11 days after 

dyspnea, nausea, confusion, metabolic acidosis, and other initial effects of acute toxic ingestion; the 

cranial neuropathy resolved over a period of 11 months (Lewis et al. 1997). In another case, a CT scan 

3 days after ingestion of approximately 24,000 mg/kg of ethylene glycol showed low density areas in the 

basal ganglia, thalami, midbrain, and upper pons (Morgan et al. 2000). Clinical findings reflected 

dysfunction in all the areas of hypodensity on the CT scan and included gaze-directed nystagmus with 

bilateral sixth cranial nerve palsies that developed 7 days following ingestion. Although a magnetic 

resonance imaging (MRI) of the brain 24 days after ingestion revealed bilateral putamen necrosis, the 

patient’s neurologic sequelae resolved over the following 4 months. 

Information on the neurotoxicity of ethylene glycol in orally-exposed animals is essentially limited to 

results of clinical observations and histopathology evaluations, as summarized below; tests of 

neurobehavioral function have not been conducted. 

Ataxia, convulsions, and/or central nervous system depression occurred in dogs given a single nonlethal 

dose of 4,880–10,743 mg/kg ethylene glycol in food (Beckett and Shields 1971; Dial et al. 1994; Grauer 

et al. 1987). Clinical signs of neurotoxicity were observed prior to death in cats given a single 

4,440 mg/kg dose by gavage; effects included abnormal gait, loss of reflexes, central nervous system 

depression (symptoms not specified), and convulsions (Penumarthy and Oehme 1975). In F344 rats, a 
 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 104 

3. HEALTH EFFECTS 

single gavage dose of 4,000 mg/kg ethylene glycol caused ataxia and coma prior to death (Clark et al. 

1979). There were no clinical signs of neurotoxicity or histopathological changes in brain or sciatic nerve 

tissue in Sprague-Dawley rats exposed to 7,327 mg/kg/day in drinking water for 10 days (Robinson et al. 

1990). 

Calcium oxalate crystals were observed in the brain of male F344 rats exposed to 5,000 mg/kg/day 

ethylene glycol in the diet for 13 weeks (Melnick 1984). The authors reported no significant tissue 

response to the crystals or clinical signs of neurotoxicity, and the effect did not occur in males at 

2,500 mg/kg/day or in females at doses as high as 10,000 mg/kg/day (highest tested dose). As indicated 

above, a similar effect occurred in humans who died from acute ethylene glycol poisoning (Friedman et 

al. 1962; Froberg et al. 2006; Hantson et al. 2002; Leth and Gregersen 2005; Zeiss et al. 1989). 

There were no clinical signs of neurotoxicity or histopathological changes in nervous system tissue in 

other intermediate- or chronic-duration studies of ethylene glycol in rats or mice. As indicated in 

Table 3-2, the histopathological evaluations included brain, spinal cord, and/or sciatic nerve in Wistar rats 

exposed to ≤2,000 mg/kg/day by gavage for 4 weeks (Schladt et al. 1998), Sprague-Dawley rats exposed 

≤5,744 mg/kg/day in drinking water for 90 days (Robinson et al. 1990), Wistar rats exposed to 

≤1,128 mg/kg/day in the diet for 16 weeks (Gaunt et al. 1974), F344 rats exposed to 1,000 mg/kg/day in 

the diet for 1 year (DePass et al. 1986a; Woodside 1982), Sprague-Dawley rats exposed to 

≤3,000 mg/kg/day in the diet for 2 years (Blood 1965), B6C3F1 mice exposed to ≤16,000 mg/kg/day in 

the diet for 13 weeks or ≤12,000 mg/kg/day in the diet for 2 years (Melnick 1984; NTP 1993), or 

CD-1 mice exposed to ≤1,000 mg/kg/day in the diet for 2 years (DePass et al. 1986a; Woodside 1982). 

The highest NOAEL values and all reliable LOAEL values for neurological effects in each species and 

duration category for ethylene glycol after oral exposure are reported in Table 3-2 and plotted in 

Figure 3-2. 

3.2.2.5 Reproductive Effects 

No studies were located regarding reproductive effects in humans after oral exposure to ethylene glycol. 

Ethylene glycol treatment did not affect gestational length in CD rats given 2,500 mg/kg/day ethylene 

glycol by gavage administration on Gd 6–15 (Marr et al. 1992). Testis and uterine weights and 
 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 105 

3. HEALTH EFFECTS 

histopathology were not affected in B6C3F1 mice treated with ethylene glycol for 4 consecutive days at 

doses up to 250 mg/kg/day and evaluated 1 day later (Hong et al. 1988). 

Reproductive function after intermediate-duration oral exposure to ethylene glycol has been tested in 

three multi-generation studies (one in rats and two in mice) and several shorter studies (15–20 days in rats 

and mice). In these studies, effects on fertility, fetal viability, and male reproductive organs were 

observed in mice, while the only effect in rats was an increase in gestational duration. 

In a continuous breeding study in which CD-1 mice were exposed to ethylene glycol in drinking water, 

there were slight, but statistically significant, reductions in the number of litters per fertile pair and in the 

mean number of live pups per litter at 1,640 mg/kg/day of the F0 generation (Lamb et al. 1985; Morrissey 

et al. 1989). In mated F1 offspring, there were no differences between high-dose and control groups in 

fertility or live litter size. In a follow-up to this study using the same overall protocol, the number of live 

female pups and the number of live pups per litter were significantly reduced at 2,826 mg/kg/day in the 

F0 generation of mice, but there were no effects on reproductive parameters in the F1 generation 

(Morrissey et al. 1989; NTP 1986). Ethylene glycol treatment did not affect mating or fertility rate in 

either generation, or in F0 parents used in a crossover mating trial (20/sex high-dose mice mated to 20/sex 

controls) (Morrissey et al. 1989; NTP 1986). Female Swiss CD-1 mice given ethylene glycol at 

2,500 mg/kg/day by gavage for 20 days including a 5-day mating period (days 8–12) with concurrently 

treated males had significantly decreased live implants and significantly increased dead implants as well 

as complete resorption of two of six litters (Harris et al. 1992). Total number of implantation sites was 

not affected. 

In a three-generation reproductive toxicity and dominant lethality study in F344 rats exposed via the diet, 

no treatment-related effects on fertility index, gestation index, gestation survival index, or days from first 

mating to litter were observed in any generation at doses up to 1,000 mg/kg/day (DePass et al. 1986b). 

Number of implantation sites was not affected at doses up to 2,250 mg/kg/day in timed pregnant CD rats 

given gavage doses of ethylene glycol on Gd 6–20 (NTP 1988). 

Effects on the male reproductive system, manifested mainly as changes in sperm parameters and testicular 

lesions, occurred in CD-1 mice exposed to ethylene glycol in drinking water in a continuous breeding 

study (Morrissey et al. 1989; NTP 1986). Sperm number was decreased in F1 males at doses as low as 

897 mg/kg/day, but the effect did not exhibit a dose-response relationship. Sperm motility, absolute 

seminal vesicle weight, relative epididymis weight, and absolute and relative testis weights were 
 

 

 

 

 

 

ETHYLENE GLYCOL 106 

3. HEALTH EFFECTS 

significantly reduced in F1 males at ≥1,798 mg/kg/day. Effects at 2,826 mg/kg/day included increased 

incidence of abnormal sperm and decreased sperm motility in F0 males, and increased incidence and 

severity of testicular and epididymal lesions in F0 males (seminiferous tubule degeneration, loss of 

spermatozoa, spermatic, spermatogonia and spermatocytes, vacuolization of epithelial cells, and 

interstitial cell hyperplasia) and F1 males (seminiferous tubule degeneration and interstitial cell 

hyperplasia). An Expert Panel review of this study (NTP-CERHR 2004) concluded that, while this study 

provided some evidence for testicular changes and effects on sperm parameters, the high incidence of 

testicular effects in the control animals limited the ability to draw conclusions about the relationship of 

this effect to treatment. Ethylene glycol treatment did not affect testis weight, epididymis weight, sperm 

count, sperm motility, or microscopic findings in testis or epididymis of male Swiss CD-1 mice treated by 

gavage at doses up to 2,500 mg/kg/day for 17 days (Harris et al. 1992). In a three-generation 

reproductive toxicity study in F344 rats exposed via the diet, no treatment-related effects on 

histopathology of male reproductive organs were observed in any generation at doses up to 

1,000 mg/kg/day (DePass et al. 1986b). 

Limited information is available on reproductive effects of ethylene glycol in female animals. In a 

continuous breeding study in which CD-1 mice were exposed to ethylene glycol in drinking water, there 

were no effects on estrous cyclicity, or weights or microscopic findings in the ovary, uterus, or vagina in 

either generation (Morrissey et al. 1989; NTP 1986). Bolon et al. (1997) sectioned the ovaries of 

10 female mice/dose from the NTP continuous breeding study (Morrissey et al. 1989; NTP 1986) and 

evaluated differential follicular counts (small, growing, and antral), observing no difference in follicular 

counts attributable to ethylene glycol treatment. In a three-generation reproductive toxicity study in 

F344 rats exposed via the diet, no treatment-related effects on gestation index or on histopathology of 

female reproductive organs were observed in any generation at doses up to 1,000 mg/kg/day (DePass et 

al. 1986b). Average gestational length was significantly longer in pregnant CD rats given gavage doses 

of 1,250 and 2,250 mg/kg/day on Gd 6–20 (NTP 1988). 

In summary, oral exposure to ethylene glycol can affect fertility and fetal viability at high doses 

(≥1,640 mg/kg/day in mice and ≥2,500 mg/kg/day in rats), and there is suggestive evidence for an effect 

on male reproductive function in mice at doses ≥897 mg/kg/day and on gestational duration in rats 

exposed to ≥1,250 mg/kg/day. The highest NOAEL values and all reliable LOAEL values for 

reproductive effects in each species and duration category for ethylene glycol after oral exposure are 

reported in Table 3-2 and plotted in Figure 3-2. 
 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 107 

3. HEALTH EFFECTS 

3.2.2.6 Developmental Effects 

No studies were located regarding developmental effects in humans after oral exposure to ethylene glycol. 

The developmental toxicity of ethylene glycol has been assessed in several acute-duration studies using 

mice, rats, and rabbits. Available studies indicate that malformations, especially skeletal malformations, 

occur in both mice and rats exposed during gestation; mice are apparently more sensitive to the 

developmental effects of ethylene glycol. Other evidence of embryotoxicity in laboratory animals 

exposed to ethylene glycol exposure includes reduction in fetal body weight. 

Studies in laboratory animals indicate that acute-duration oral exposure to high doses of ethylene glycol 

during gestation can affect fetal viability and postimplantation loss. Of 37 pregnancies in CD-1 mice 

receiving gavage doses of 11,090 mg/kg/day on Gd 7–14, only 15 litters had at least 1 live-born pup, 

compared with 29/29 control pregnancies (Schuler et al. 1984). In the treated group, there was a 

significant decrease in the number of live pups per litter and a significant increase in the number of dead 

pups per litter at birth. Ethylene glycol treatment (up to 2,500 mg/kg/day) of mated female Swiss 

CD-1 mice during Gd 8–14 did not affect the number of females littering, number of implantation sites, or 

number of live pups at birth (Harris et al. 1992). The percentage of postimplantation loss per litter was 

significantly increased in CD rats treated by gavage on Gd 6–15 with 5,000 mg/kg/day and the number of 

live fetuses per litter was reduced at both 2,500 and 5,000 mg/kg/day (Price et al. 1985). There were no 

significant effects of treatment on total implantations, preimplantation loss, or litter size when pregnant 

F344 rats were given ethylene glycol in the diet at target doses of up to 1,000 mg/kg/day on Gd 6–15 

(Maronpot et al. 1983). In New Zealand white rabbits given gavage doses of up to 2,000 mg/kg/day 

ethylene glycol on Gd 6–19, the numbers of pre- or post-implantation losses were not increased in any 

treatment group, although 42% of the high-dose dams died prior to sacrifice (Tyl et al. 1993). 

The most sensitive indicator of the developmental toxicity of acute oral exposure to ethylene glycol 

appears to be an increased incidence of malformations, primarily skeletal malformations, in both mice and 

rats. Available data suggest that malformations appear in mice at lower gavage doses than those that 

cause malformations in rats. The incidence of skeletal and other malformations was increased at all doses 

when groups of at least 20 timed-pregnant CD-1 mice were treated by gavage with ethylene glycol doses 

of 0, 750, 1,500, or 3,000 mg/kg/day on Gd 6–15 (Price et al. 1985). The percentages of malformed 

fetuses per litter and of litters with one or more malformed fetuses were significantly increased at all 

doses. The malformations primarily consisted of neural tube, craniofacial, and axial skeletal defects, with 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 108 

3. HEALTH EFFECTS 

skeletal defects comprising the majority. Minimal maternal toxicity (decreased body weight gain and 

liver weight) was observed at doses ≥1,500 mg/kg/day. In a later study aimed at identifying a NOAEL

for developmental effects in CD-1 mice, an increased incidence of malformations was observed at gavage 

doses ≥500 mg/kg/day on Gd 6–15 (Neeper-Bradley et al. 1995; Tyl 1989). The incidence of total 

malformations per litter (external, visceral, and skeletal) was significantly increased at both 500 and 

1,500 mg/kg/day. There was a significant increase in the incidence of two skeletal malformations (fused 

ribs or thoracic arches) in the 1,500 mg/kg/day group, and the incidences of 23 skeletal variations were 

also increased in this group. One of these variations (bilateral extra rib 14) was also significantly 

increased at 500 mg/kg/day. The incidence of individual external or visceral malformations was not 

significantly increased in any treatment group relative to the vehicle control; however, exencephaly (a 

malformation observed by Price et al. [1985] at higher doses) was observed in two fetuses in the 

500 mg/kg/day group and in three fetuses of the 1,500 mg/kg/day dose group (Neeper-Bradley et al. 1995; 

Tyl 1989). No evidence of maternal toxicity was observed at any dose in this study. 

In rats, gestational gavage doses of at least 1,000 mg/kg/day were required to induce malformations. The 

number of litters with malformations, number of malformed fetuses per litter, and number of litters with 

skeletal malformations were increased at doses ≥2,500mg/kg/day in CD rats treated on Gd 6–15 (Price et 

al. 1985). At 5,000 mg/kg/day, the number of litters with fetuses having external and visceral 

malformations (primarily neural tube and craniofacial defects) was also increased. The authors reported a 

significant increase in visceral malformations at 1,250 mg/kg/day, but NTP-CERHR (2004) classified the 

observed effects (hydroureter, hydronephrosis, and great artery anomalies) as variations rather than 

malformations, and characterized the 1,250 mg/kg/day dose as a developmental NOAEL. In later studies 

using lower doses, the incidence of litters with fetuses having two skeletal malformations (missing 

thoracic arch and missing ribs) was increased in CD rats administered gavage doses ≥1,000mg/kg/day on 

Gd 6–15 (Neeper-Bradley 1990; Neeper-Bradley et al. 1995). The incidences of total skeletal 

malformations and skeletal variations (delayed ossification) were also significantly increased at 

≥1,000 mg/kg/day. The highest dose (2,500 mg/kg/day) was associated with increased frequencies of 

visceral and external malformations, including gastroschisis, hydrocephaly, lateral ventricle dilation, 

umbilical hernia, and atelectasis (Neeper-Bradley 1990; Neeper-Bradley et al. 1995). No evidence of 

maternal toxicity was observed at doses as high as 1,000 mg/kg/day in this study. 

Reduced ossification of the vertebral centra was observed in the 1,000 mg/kg/day dose group when 

F344 rats were given ethylene glycol in the diet on Gd 6–15 (Maronpot et al. 1983). However, an Expert 

Panel Review of this study (NTP-CERHR 2004) identified the high dose (1,000 mg/kg/day) as a 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 109 

3. HEALTH EFFECTS 

developmental NOAEL, noting the lack of other findings (change in body weights or consistent 

alterations in skeletal integrity) to support the authors’ suggestion that reduced ossification was indicative 

of minimal embryotoxicity. No maternal toxicity was observed (Maronpot et al. 1983). 

When developmental effects were assessed over the course of postnatal development, there were 

significant reductions in percentages of total ossification, sternebral ossification, and vertebral centra 

ossification on Gd 20 and at all postnatal evaluations up to ppd 63 in CD rats gavaged with ethylene 

glycol at 2,500 mg/kg/day on Gd 6–15 (Marr et al. 1992). The percent of malformed fetuses per litter was 

also significantly increased at all scheduled sacrifice times other than ppd 63. The percent of litters with 

skeletal malformations (primarily skeletal axial defects) was 100% in the treated litters at all time points 

other than ppd 63 (Marr et al. 1992). Maternal toxicity (reduced weight gain) was also observed at this 

dose (2,500 mg/kg/day) (Marr et al. 1992). 

Fetal body weight and postnatal weight gain are also sensitive indicators of embryotoxicity after ethylene 

glycol treatment, albeit at higher doses than skeletal and other malformations in mice. Average fetal body 

weight per litter was significantly decreased in CD-1 mice treated by gavage with doses ≥750 mg/kg/day 

ethylene glycol on Gd 6–15 (Price et al. 1985), although in a later study in the same strain, average fetal 

body weight per litter was reduced only at 1,500 mg/kg/day on Gd 6–15 (Neeper-Bradley et al. 1995; Tyl 

1989). Ethylene glycol treatment of Swiss Crl:CD-1 mice by gavage at 2,500 mg/kg/day on Gd 8–14 

resulted in decreased pup body weight on ppd 1 and 4 (Harris et al. 1992). There were significant 

decreases in pup birth weight as well as pup weight gain and survival over ppd 1–3 in CD-1 mice given 

11,090 mg/kg/day ethylene glycol by gavage on Gd 7–14 (Schuler et al. 1984). In CD rats, fetal body 

weight was significantly decreased at gavage doses ≥1,000 mg/kg/day (Neeper-Bradley 1990; NeeperBradley et al. 1995) or ≥2,500 mg/kg/day (Price et al. 1985) on Gd 6–15. In another study, when CD rats 

were given 2,500 mg/kg/day ethylene glycol by gavage on Gd 6–15, mean pup body weight per litter was 

significantly lower than controls on ppd 1, but was not different from controls at later postnatal 

evaluations (Marr et al. 1992). 

A single study in rabbits suggests that, in this species, developmental toxicity may not occur at acute 

doses that are not maternally toxic. There was significant mortality (42%) at 2,000 mg/kg/day in New 

Zealand white rabbits given gavage doses of ethylene glycol on Gd 6–19 (Tyl et al. 1993). One doe 

aborted and three delivered early at this dose, but there was no evidence of developmental toxicity in live 

litters at any exposure level. 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 110 

3. HEALTH EFFECTS 

One gestational exposure study, a 20-day exposure study, and three multi-generation reproductive toxicity 

studies with some developmental toxicity end points are available to assess developmental effects of 

intermediate-duration exposure to ethylene glycol. As with acute exposure, intermediate-duration 

exposure was associated with malformations, decreases in pup body weight, and effects on fetal viability 

in both rats and mice. 

In a continuous breeding study, skeletal evaluation of F1 offspring of CD-1 mice exposed to 

1,640 mg/kg/day exhibiting facial anomalies indicated a pattern of skeletal defects affecting the skull, 

sternebrae, ribs, and vertebrae in both sexes (Lamb et al. 1985; Morrissey et al. 1989). Bone morphology, 

but not histology, differed in the affected mice. In a follow-up study using a similar design, similar facial 

abnormalities were observed in F1 mice treated with 1,798 or 2,826 mg/kg/day (Morrissey et al. 1989; 

NTP 1986). There was a significant increase in the incidence of skeletal malformations (rib, sternebral, 

and vertebral defects) at 2,250 mg/kg/day ethylene glycol when CD rats were given gavage doses on 

Gd 6–20; the authors noted that 9/443 pups in this group also had hydrocephaly (NTP 1988). In this 

study, evidence of maternal effects (increased gestational length and renal lesions) occurred at a lower 

dose (1,250 mg/kg/day) (NTP 1988). 

Average pup weight was reduced in the F0 generation at 1,640 mg/kg/day in a continuous breeding study 

in CD-1 mice (Lamb et al. 1985; Morrissey et al. 1989), but female pup body weights and pup weight 

adjusted for litter size were significantly reduced at doses as low as 897 mg/kg/day in both F0 and 

F1 generations in a follow-up study (Morrissey et al. 1989; NTP 1986). In a crossover mating trial using 

the F0 parents, pup body weight were reduced when 2,826 mg/kg/day females were mated to control 

males (Morrissey et al. 1989; NTP 1986). In studies on the postnatal effects of intrauterine exposure, 

average pup body weights were not affected on ppd 4, 14, or 21 in F344 rats exposed via the diet to doses 

up to 1,000 mg/kg/day in a three-generation reproductive toxicity study (DePass et al. 1986b); however, 

pup body weights were lower than controls at various times between ppd 1 and 22 when CD rats were 

administered 2,250 mg/kg/day ethylene glycol by gavage on Gd 6–20 (NTP 1988). Postnatal decreases in 

kidney weight (1,250 and 2,250 mg/kg/day groups) and brain weight (2,250 mg/kg/day group), without 

corresponding histopathology changes, have also been observed in the offspring of rats exposed in utero 

(Gd 6–20) to ethylene glycol (NTP 1988). 

Dams exposed to 2,500 mg/kg/day ethylene glycol had significantly fewer live implants and significantly 

more dead implants as well as complete resorption of two of six litters in a study exposing female Swiss 

CD-1 mice by gavage at doses up to 2,500 mg/kg/day for 20 days including a period of mating to 
 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 111 

3. HEALTH EFFECTS 

concurrently treated males (Harris et al. 1992). In a study of postnatal effects of intrauterine exposure, 

cumulative pup mortality was significantly higher on ppd 1 and 4 in CD rats administered 

2,250 mg/kg/day ethylene glycol by gavage on Gd 6–20 (NTP 1988). 

In summary, there is a substantial database demonstrating developmental toxicity in rats and mice at 

ethylene glycol doses that are not maternally toxic. Mice appear to be more vulnerable to the 

developmental effects of ethylene glycol, responding at lower doses than rats. Skeletal and other 

malformations appear to be the most sensitive indicators of toxicity, with effects observed at bolus doses 

≥500 mg/kg/day in mice and ≥1,000 mg/kg/day in rats. Effects on fetal body weight and fetal viability 

occur at higher doses. The highest NOAEL values and all reliable LOAEL values for developmental 

effects in each species and duration category for ethylene glycol after oral exposure are reported in 

Table 3-2 and plotted in Figure 3-2. 

3.2.2.7 Cancer 

No studies were located regarding carcinogenicity in humans after oral exposure to ethylene glycol. 

Comprehensive histopathological evaluations showed no evidence of carcinogenicity in Sprague-Dawley 

rats exposed to ≤3,000 mg/kg/day in the diet for 2 years (Blood 1965), F344 rats exposed to 

1,000 mg/kg/day in the diet for 1 year (DePass et al. 1986a; Woodside 1982), B6C3F1 mice exposed to 

≤12,000 mg/kg/day in the diet for 2 years (Melnick 1984; NTP 1993), or CD-1 mice exposed to 

≤1,000 mg/kg/day in the diet for 2 years (DePass et al. 1986a; Woodside 1982). 

3.2.3 Dermal Exposure 

Dermal exposure, through activities such as changing antifreeze, is the most likely route of exposure to 

ethylene glycol, but dermal exposure is not likely to lead to toxic effects. 

3.2.3.1 Death 

No studies were located regarding death in humans or animals after dermal exposure to ethylene glycol. 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 112 

3. HEALTH EFFECTS 

3.2.3.2 Systemic Effects 

No studies were located regarding respiratory, cardiovascular, gastrointestinal, hematological, 

musculoskeletal, hepatic, renal, endocrine, dermal, ocular, body weight, or metabolic effects in humans or 

respiratory, cardiovascular, gastrointestinal, hematological, musculoskeletal, endocrine, or metabolic 

effects in animals after dermal exposure to ethylene glycol. 

The highest NOAEL values for systemic effects in each species and duration category for ethylene glycol 

after dermal exposure are reported in Table 3-3. 

Hepatic Effects. Maternal liver weight was not affected in female CD-1 mice exposed to 

3,549 mg/kg/day ethylene glycol for 6 hours/day on Gd 6–15 by occluded dermal application; liver 

histopathology was not evaluated (Tyl 1988b; Tyl et al. 1995c). 

Renal Effects. Evaluations of maternal kidney weight and kidney histopathology showed no effects 

female CD-1 mice exposed to 3,549 mg/kg/day ethylene glycol for 6 hours/day on Gd 6–15 by occluded 

dermal (Tyl 1988b; Tyl et al. 1995c). 

Dermal Effects. Minimal skin irritation occurred in New Zealand white rabbits 24–72 hours after 

application of 0.5 mL (550 mg) ethylene glycol to shaved skin (Clark et al. 1979). Female mice exposed 

to 3,549 mg/kg/day ethylene glycol for 6 hours/day on Gd 6–15 by occluded dermal application showed 

no dermal effects (Tyl 1988b; Tyl et al. 1995c). 

Ocular Effects. Ocular instillation of 0.1 mL (110 mg) ethylene glycol caused mild eye irritation in 

rabbits; transient conjunctival redness was the most prominent response (Clark et al. 1979). 

Body Weight Effects. Maternal CD-1 mice showed no changes in body weight after exposure to 

3,549 mg/kg/day ethylene glycol for 6 hours/day on Gd 6–15 by occluded dermal application (Tyl 1988b; 

Tyl et al. 1995c). 

3.2.3.3 Immunological and Lymphoreticular Effects 

No studies were located regarding immunological and lymphoreticular effects in humans or animals after 

dermal exposure to ethylene glycol. 
N49

mg/kg

mg/kg/day

mg/kg

mg/kg

N50 mgN51 mg304

mg/kg/day

N52

mg/kg/day

Table 3-3 Levels of Significant Exposure to Ethylene Glycol - Dermal 

Exposure/ LOAEL

Duration/

Species Frequency Reference (Route) (Strain) System NOAEL Less Serious Serious Chemical Form 

ACUTE EXPOSURE 

Systemic 

Mouse 10 d (CD-1) Gd 6-15 6 hr/d 

Rabbit once (New Zealand) 

Rabbit once (New Zealand) 

Reproductive 

Mouse 10 d (CD-1) Gd 6-15 6 hr/d 

Developmental 

Mouse 10 d (CD-1) Gd 6-15 6 hr/d 

Tyl 1988b; Tyl et al. 199Clark et al. 1979 Clark et al. 1979 Tyl 1988b; Tyl et al. 199Tyl 1988b; Tyl et al. 199

Hepatic Renal 

Dermal 

Bd Wt 

Dermal Ocular 

3549 F 

mg/kg 

3549 F 

mg/kg/day 

3549 F 

mg/kg 

3549 F 

mg/kg 

550 F 

mg 

110 F 

mg 

3549 

mg/kg/day 

3549 

mg/kg/day 

Bd Wt = body weight; d = day(s); F = Female; Gd = gestational day; hr = hour(s); LOAEL = lowest-observed-adverse-effect level; M = male; min = minute(s); NOAEno-observed-adverse-effect level; Resp = respiratory 
 

 

 

 

ETHYLENE GLYCOL 114 

3. HEALTH EFFECTS 

3.2.3.4 Neurological Effects 

No studies were located regarding neurological effects in humans or animals after dermal exposure to 

ethylene glycol. 

3.2.3.5 Reproductive Effects 

No studies were located regarding reproductive effects in humans after dermal exposure to ethylene 

glycol. 

Reproductive function has not been assessed in animals exposed dermally to ethylene glycol. In an acuteduration developmental toxicity study, pregnant CD-1 mice exposed to ethylene glycol at doses up to 

3,549 mg/kg on Gd 6–15 by occluded dermal application exhibited no adverse effects on the number of 

resorptions or number of total, viable, or nonviable implants per litter (Tyl 1988b; Tyl et al. 1995c). 

The highest NOAEL value for reproductive effects in mice for the acute-duration category for ethylene 

glycol after dermal exposure is reported in Table 3-3. 

3.2.3.6 Developmental Effects 

No studies were located regarding developmental effects in humans after dermal exposure to ethylene 

glycol. 

In the single acute-duration dermal study of developmental toxicity, groups of 30 pregnant CD-1 mice 

were treated with 6-hour daily dermal exposures to ethylene glycol by occluded cutaneous application on 

Gd 6–15 (Tyl et al. 1995c). The authors estimated the applied doses to be 404, 1,677, or 

3,549 mg/kg/day. Neither implantations nor resorptions were affected by treatment. The incidence of 

malformations (individual or total external, visceral, or skeletal) was not significantly increased in any 

ethylene glycol dermal treatment group, but was significantly increased in the positive (ethylene glycol by 

gavage) control group. There were significant increases in the incidence of litters with two skeletal 

variations (reduced ossification of the skull bone and phalanges) at 3,549 mg/kg/day. 

The highest NOAEL value for developmental effects in mice for the acute-duration category for ethylene 

glycol after dermal exposure is reported in Table 3-3. 
 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 115 

3. HEALTH EFFECTS 

3.2.3.7 Cancer 

No studies were located regarding cancer effects in humans or animals after dermal exposure to ethylene 

glycol. 

3.3 GENOTOXICITY 

Studies in humans have not addressed the genotoxic effects of ethylene glycol. However, available 

in vivo and in vitro laboratory studies provide consistently negative genotoxicity results for ethylene 

glycol. 

In F344 rats that received oral doses of 40, 200, and 1,000 mg/kg/day for three generations, there were no 

dominant lethal mutations (DePass et al. 1986b). 

Table 3-4 summarizes information from available in vitro studies. Ethylene glycol produced consistently 

negative results in the Ames assay for reverse mutation in several strains of Salmonella typhimurium (Clark 

et al. 1979; Kubo et al. 2002; McCann et al. 1975; Pfeiffer and Dunkelberg 1980; Zeiger et al. 1987). No 

growth inhibition due to DNA damage by ethylene glycol was observed in a battery of E. coli repairdeficient strains (McCarroll et al. 1981). Negative results were also obtained in two sets of studies when 

ethylene glycol was tested for gene mutation in the yeast, Schizosaccharomyces pombe (Abbondandolo et 

al. 1980), and for aneuploidy induction in the fungus, Neurospora crassa (Griffiths 1979, 1981). Ethylene 

glycol did not induce gene mutations in L5178Y mouse lymphoma cells (McGregor et al. 1991) 

deoxyribonucleic acid (DNA) strand breaks in primary rat hepatocytes (Storer et al. 1996). 

Two recent genotoxicity assays have been developed and tested against results of standard genotoxicity 

assays for a variety of chemicals, including ethylene glycol. Ethylene glycol did not induce gene mutation 

in a low volume, high-throughput forward mutation assay using a TA100-derived 5-fluorouracil-resistant 

strain of S. typhimurium (Miller et al. 2005). Ethylene glycol did not induce DNA damage in a highthroughput (GreenScreen HC) assay that links the regulation of the human GADD45a gene to the 

production of Green Fluorescent Protein (Hastwell et al. 2006). 
 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 116 

3. HEALTH EFFECTS 

Table 3-4. Genotoxicity of Ethylene Glycol In Vitro 

Results 

With Without 

Species (test system) End point activation activation Reference 

Prokaryotic organisms: 

Salmonella typhimurium 

(Ames test in strains TA98, 

TA100, TA1535, TA1537, 

TA1538) 

Gene mutation – – Clark et al. 1979 

S. typhimurium 

(Ames test in strains TA97, 

TA98, TA100) 

Gene mutation – – Kubo et al. 2002 

S. typhimurium 

(Ames test in strains TA98, 

TA100, TA1535, TA1537) 

Gene mutation – No data McCann et al. 1975 

S. typhimurium 

(Ames test in strains TA98, 

TA100, TA1535, TA1537) 

Gene mutation No data – Pfeiffer and Dunkelberg 

1980 

S. typhimurium 

(Ames test in strains TA97, 

TA98, TA100, TA1535, 

TA1537) 

Gene mutation – – Zeiger et al. 1987 

S. typhimurium 

(Forward mutation in TA100 

derived 5-fluorouracilresistant strain) 

Gene mutation – – Miller et al. 2005 

Escherichia coli DNA damage – – McCarroll et al. 1981 

Eukaryotic organisms: 

Yeast: 

Schizosaccharomyces 

pombe 

Gene mutation – – Abbondandolo et al. 1980 

Fungi: 

Neurospora crassa Aneuploidy 

induction 

No data – Griffiths 1979, 1981 

Mammalian cells: 

Mouse (L5178Y cells) Gene mutation – – McGregor et al. 1991 

Rat (hepatocytes) DNA breaks No data – Storer et al. 1996 

Human (GreenScreen HC 

assay using TK6 cell line) 

DNA damage No data – Hastwell et al. 2006 

C = negative result 
 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 117 

3. HEALTH EFFECTS 

3.4 TOXICOKINETICS 

Ethylene glycol is quickly and extensively absorbed through the gastrointestinal tract. Limited 

information suggests that it is also absorbed through the respiratory tract; dermal absorption is apparently 

slow. Following absorption, ethylene glycol is distributed throughout the body according to total body 

water. In most mammalian species, including humans, ethylene glycol is initially metabolized by alcohol 

dehydrogenase to form glycolaldehyde, which is rapidly converted to glycolic acid and glyoxal by 

aldehyde oxidase and aldehyde dehydrogenase. These metabolites are oxidized to glyoxylate; glyoxylate 

may be further metabolized to formic acid, oxalic acid, and glycine. Breakdown of both glycine and 

formic acid can generate CO2, which is one of the major elimination products of ethylene glycol. In 

addition to exhaled CO2, ethylene glycol is eliminated in the urine as both the parent compound and 

glycolic acid. Elimination of ethylene glycol from the plasma in both humans and laboratory animals is 

rapid after oral exposure; elimination half-lives are in the range of 1–4 hours in most species tested. 

3.4.1 Absorption 

3.4.1.1 Inhalation Exposure 

Limited information suggests that ethylene glycol is absorbed across the human respiratory tract. 

Inhalation of aerosolized ethylene glycol from an automobile heater resulted in a blood ethylene glycol 

level of 28 mg/dL (Wezorek et al. 1995). When two male volunteers inhaled 13C-labeled ethylene glycol 

vapor (estimated to result in inhaled doses of 0.96 and 1.51 mg/kg body weight), 13C-ethylene glycol and 

13C2-glycolic acid were detected in the plasma and urine, providing evidence of absorption (Carstens et al. 

2003). Similar results were obtained from two other volunteers exposed to 13C-ethylene glycol vapors 

(Upadhyay et al. 2008). No increase, as compared to controls, in serum or urinary levels of ethylene 

glycol was recorded in men exposed to 17–49 mg/m3 ethylene glycol aerosol for 30 days (Wills et al. 

1974). However, in a review of this study, NTP-CERHR (2004) noted that the analytical techniques used 

for serum and urine analysis of ethylene glycol may not have been adequately sensitive to detect a 

difference. 

In rats exposed nose-only for 30 minutes to 14C-ethylene glycol vapor (32 mg/mg3

) or for 17 minutes to 

14C-ethylene glycol aerosol (184 mg/m3

) on gallium oxide particles, between 75 and 85% of the deposited 

radiolabel was found to be distributed throughout the body regardless of the form of the compound 
 

 

 

 

 

 

 

ETHYLENE GLYCOL 118 

3. HEALTH EFFECTS 

(Marshall and Cheng 1983). In its review, NTP-CERHR (2004) estimated that 60–90% of the inhaled 

dose was absorbed in this study. 

3.4.1.2 Oral Exposure 

Indirect evidence of the oral absorption of ethylene glycol by humans is available from case reports of 

clinical symptoms in persons accidentally or intentionally ingesting ethylene glycol (Hewlett et al. 1986; 

Jacobsen et al. 1988; Robinson and McCoy 1989; Walton 1978). Direct evidence of absorption comes 

from measurements of the plasma concentration of ethylene glycol after acute poisoning (studies report 

levels ranging from 1 to 40 mmol/L; Hewlett et al. 1986; Jacobsen et al. 1988); however, because the 

amounts ingested in these events were generally unknown, and blood analyses were performed at varying 

times after exposure, the data are not useful for quantifying the rate or extent of oral absorption in 

humans. 

In rats, ingested ethylene glycol is rapidly absorbed, usually reaching peak blood levels within 1 hour 

after single gavage doses of 150–20,000 mg/kg (Frantz et al. 1989, 1996a, 1996c; Pottenger et al. 2001; 

Winek et al. 1978). Absorption is equally rapid in other species, with peak blood levels reached within 1– 

3 hours after gavage exposure in mice, monkeys, dogs, and pregnant rabbits (Carney et al. 2008; Frantz et 

al. 1991, 1996a, 1996b; Grauer et al. 1987; Hewlett et al. 1989; McChesney et al. 1971). In addition, 

available data suggest near complete absorption of ingested ethylene glycol in both rats and mice. After 

gavage doses of 10 and 1,000 mg/kg 14C-ethylene glycol to both rats and mice, the areas under the 

ethylene glycol plasma concentration versus time curves were comparable to those observed with 

equivalent intravenous doses (Frantz et al. 1989, 1991, 1996a). 

Results of one study suggest that pregnancy does not alter absorption kinetics in rats dosed once on 

Gd 10. The time course and peak plasma levels of ethylene glycol did not differ between pregnant and 

nonpregnant rats given 10 or 2,500 mg/kg by gavage (Pottenger et al. 2001). 
 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 119 

3. HEALTH EFFECTS 

3.4.1.3 Dermal Exposure 

Information regarding the dermal absorption of ethylene glycol in humans is limited. Upadhyay et al. 

(2008) applied 0.8 mL of 13C-ethylene glycol to the forearm (occluded) of each of three volunteers for 

4 or 6 hours and assessed the appearance of 13C-ethylene glycol and 13C-glycolic acid in serum and urine. 

Their results indicated that only 1.0–1.3% of the epidermally-applied dose was absorbed. A skin 

permeability constant of 0.000027 cm/hour was calculated. 

In vivo studies with rats and mice suggest incomplete dermal absorption of ethylene glycol. In rats 

exposed to occluded dermal doses (applied to thoracic dorsal area after light clipping of fur) of 10 or 

1,000 mg/kg 14C-ethylene glycol or 1,000 mg/kg of a 50% solution of 14C-ethylene glycol, measurement 

of radioactivity recovered in body tissues, excreta, and exhaled air suggested apparent absorption of 26– 

32% of the administered dose (Frantz et al. 1989, 1996b). In the same study, similar treatment of mice 

with 100 or 1,000 mg/kg 14C-ethylene glycol or 1,000 mg/kg of 50% 14C-ethylene glycol lead to apparent 

absorption estimates ranging from 60 to 84% (Frantz et al. 1991, 1996b). 

3.4.2 Distribution 

3.4.2.1 Inhalation Exposure 

Data on the tissue distribution of ethylene glycol in humans exposed via inhalation are not available. 

Based on plasma concentrations of ethylene glycol in two volunteers who inhaled doses of 0.96 and 

1.51 mg/kg, Carstens et al. (2003) estimated the volumes of distribution (Vd) to be 0.78 and 0.91 L/kg. A 

similar result was obtained from another volunteer who inhaled ethylene glycol vapors (Upadhyay et al. 

2008). 

In rats inhaling 14C-ethylene glycol vapor (32 mg/m3 for 30 minutes) or aerosol (184 mg/mg3 for 

17 minutes), radioactivity was distributed quickly (Marshall and Cheng 1983). The authors estimated that 

60% of ethylene glycol (in either form) was deposited in the respiratory tract, primarily in the nasal 

cavity, and 75–80% of the initial body burden was distributed throughout the body upon sacrifice 

immediately after exposure (Marshall and Cheng 1983). 

3.4.2.2 Oral Exposure 

After oral exposure, ethylene glycol is distributed throughout the body according to total body water. The 

apparent volume of distribution of ethylene glycol in humans exposed orally has been estimated to be 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 120 

3. HEALTH EFFECTS 

0.54–0.56 L/kg based on clearance data in two patients poisoned with ethylene glycol (Jacobsen et al. 

1988). The ratios of urine to plasma ethylene glycol concentration in one patient were similar to those of 

ethanol, indicating distribution with total body water. 

In rats, 6–22% of the radioactivity derived from single oral doses of 10 and 1,000 mg/kg of 14C-ethylene 

glycol were recovered from body tissues and carcass (combined) 96 hours after exposure (Frantz et al. 

1989, 1996b, 1996c); mice retained similar percentages (3–11%) in their tissues following single oral 

doses across the same range (Frantz et al. 1991, 1996b). Among the few tissues examined individually 

(liver, kidney, brain, fat, and lung), the highest radioactivity was found in the liver of both species (see 

Table 3-5). In two Rhesus monkeys given single oral doses of about 1,100 mg/kg unlabeled ethylene 

glycol, the parent compound was evenly distributed throughout the tissues 4 hours after exposure; tissue 

to plasma concentration ratios ranged from 0.85 to 1.91 for the brain, heart, kidney, gastrointestinal tract, 

liver, lung, muscle, pancreas, and spleen (McChesney et al. 1971). 

Ethylene glycol crosses the placenta and enters the developing fetus. In a toxicokinetic study of orally 

exposed pregnant rabbits, ethylene glycol levels were measured in maternal blood and kidney tissue as 

well as yolk sac cavity fluid, the yolk sac itself, and fetal tissues (Carney et al. 2008). Measured ethylene 

glycol concentrations were initially somewhat lower in the yolk sac cavity fluid than those of maternal 

blood, but were slightly higher during the elimination phase (Carney et al. 2008). Levels of unchanged 

ethylene glycol in yolk sac and embryos were approximately 14–20% of the level in maternal blood. In a 

study designed to compare levels of ethylene glycol, glycolic acid, and oxalic acid in maternal blood and 

extraembryonic fluids of rats and rabbits (Carney et al. 1998), gavage doses of 500 or 2,500 mg/kg 

ethylene glycol were administered to pregnant rats and rabbits on Gd 10 or 9, respectively. Maternal 

blood levels of ethylene glycol were similar in the rats and rabbits, indicating no significant species 

differences in absorption. Ethylene glycol levels were determined in the extraembryonic fluid of both 

species and were found to be approximately 2-fold higher in the rat compared to the rabbit. 

3.4.2.3 Dermal Exposure 

Frantz et al. (1989, 1996b, 1996c) evaluated the distribution of a 10 or 1,000 mg/kg dose of undiluted 

14C-ethylene glycol or a 1,000 mg/kg dose of 50% aqueous 14C-ethylene glycol applied dermally to rats 

under an occlusive bandage. Table 3-6 shows the disposition of radioactivity. The pelt contained the 

highest radioactivity (5–6% of applied dose) among the tissues examined (liver, kidney, brain, lung, pelt, 

and remaining carcass) (Frantz et al. 1989, 1996b). Similar experiments in mice at doses of 100 or 
 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 121 

3. HEALTH EFFECTS 

Table 3-5. Distribution of Radioactivity (Percent of Administered Dose) in 

Tissues 96 Hours After Oral or Percutaneous Exposure to 

14C-Ethylene Glycol 

Oral Percutaneous 

1,000 mg/kg 

10 mg/kg 1,000 mg/kg (50% 

10 mg/kg 1,000 mg/kg (undiluted) (undiluted) solution) 

Female rats 

Liver 2.43±0.44a 0.74±0.22 0.69±0.38 0.47±0.07 0.48±0.11

 Kidney 0.20±0.02 0.10±0.01 0.06±0.03 0.03±0.00 0.03±0.00

 Brain 0.05±0.01 0.02±0.01 0.01±0.01 0.01±0.00 0.01±0.00

 Lung 0.14±0.01 0.06±0.01 0.04±0.02 0.02±0.00 0.02±0.00

 Carcass 9.58±1.24 4.20±0.13 2.24±1.25 1.39±0.18 1.70±0.35

 Pelt 2.78±0.34 1.21±0.16 5.09±4.28 5.24±2.53 5.84±1.04 

Male rats

 Liver 2.29±0.39 0.88±0.17 1.06±0.10 0.53±0.09 0.39±0.09

 Kidney 0.24±0.03 0.88±0.17 0.09±0.01 0.05±0.01 0.03±0.01

 Brain 0.04±0.00 0.01±0.00 0.02±0.00 0.01±0.00 0.01±0.00

 Lung 0.13±0.02 0.06±0.01 0.04±0.01 0.02±0.01 0.01±0.00

 Testis 0.12±0.02 0.06±0.01 0.05±0.00 0.03± 0.01 0.01±0.00

 Carcass 11.60±1.09 4.97±0.52 3.39±0.72 2.10±0.48 1.34±0.20

 Pelt 7.28±0.99 3.67±1.21 3.36±0.26 6.94±3.90 5.18±1.18 

Female mice 

Liver 3.02±0.95 0.63±0.16 0.60±0.06 0.59±0.16 0.58±0.07

 Kidney 0.30±0.13 0.11±0.01 0.06±0.01 0.07±0.02 0.06±0.02

 Brain 0.09±0.04 0.05±0.00 0.02±0.01 0.02±0.01 0.02±0.01

 Lung 0.11±0.05 0.05±0.01 0.02±0.00 0.28±0.01 0.02±0.01

 Carcass/pelt 7.21±2.01 2.56±0.28 14.77±3.85 7.59±2.03 10.10±0.79 

a

Mean±standard deviation from groups of four animals. 

Source: Frantz et al. 1996b, 1996c 
 

 

 

 

 

 

 

ETHYLENE GLYCOL 122 

3. HEALTH EFFECTS 

Table 3-6. Radioactivity (Percent of Administered Dose) in Excreta 96 Hours 

After 6-Hour Occluded Percutaneous Exposure to 14C-Ethylene Glycol
 

Undiluted 50% Aqueous solution 

10 mg/kg 1,000 mg/kg 1,000 mg/kg 

Female rats 

Expired CO2 13.1±7.2a 11.4±1.8 9.3±1.9 

Urine 8.2±4.7 7.6±0.9 4.4±0.7 

Feces 1.1±0.7 1.4±1.0 0.5±0.2 

Tissues 6.0±4.6 5.8±2.5 6.4±1.2 

Carcass 2.2±1.2 1.4±0.2 1.7±0.4 

Occlusion materials and skin 10.9±3.3 55.6±2.2 56.8±4.2 

Total recoveryb 42.4±19.2 84.7±2.0 82.7±4.5 

Male rats 

Expired CO2 14.0±1.1 14.4±4.4 5.9±2.0 

Urine 6.7±0.8 8.1±2.5 4.6±1.4 

Feces 1.1±0.5 0.6±0.1 0.6±0.1 

Tissues 4.7±0.4 7.6±3.9 5.6±1.2 

Carcass 3.4±0.7 2.1±0.5 1.3±0.2 

Occlusion materials and skin 17.4±3.1 48.2±9.4 59.2±6.7 

Total recoveryc 48.9±5.0 83.8±4.1 81.2±3.8 

Female mice 

Expired CO2 10.4±2.0 15.9±4.8 10.4±3.2 

Exhaled VOCs 34.0±5.9 33.1±8.6 20.9±2.6 

Urine 6.7±2.8 12.3±5.6 5.4±1.6 

Feces 6.1±2.4 7.5±1.7 6.4±2.4 

Tissues 0.7±0.1 0.7±0.2 0.7±0.1 

Carcass 14.8±3.8 7.6±2.0 10.0±0.8 

Occlusion materials and skin 23.0±4.6 4.8±4.2 25.4±15.3 

Total recoveryd 99.5±9.4 89.2±3.9 85.2±6.7 

a

Mean±standard deviation from groups of four animals

b

Cage wash accounted for 0.9–4%
 c

Cage wash accounted for 2–4% d

Cage wash accounted for 4–7%
 

CO2 = carbon dioxide; VOCs = volatile organic compounds 

Source: Frantz et al. 1996b, 1996c 
 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 123 

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1,000 mg/kg undiluted 14C-ethylene glycol or 1,000 mg/kg 50% aqueous solution of 14C-ethylene glycol 

showed the highest radioactivity in the carcass and pelt combined (~8–15%) (Frantz et al. 1991, 1996b). 

3.4.3 Metabolism 

The metabolic pathway for ethylene glycol is shown in Figure 3-3. Asterisks indicate rate-limiting steps 

in the pathway. The metabolism of ethylene glycol was reviewed by NTP-CERHR (2004) and Slikker et 

al. (2004). Ethylene glycol is converted to glycolaldehyde by nicotinamide adenine dinucleotide (NAD)-

dependent alcohol dehydrogenase. Subsequent reduction of NAD results in the formation of lactic acid 

from pyruvate. Glycolaldehyde has a brief half-life and is rapidly converted to glycolic acid (and to a 

lesser extent glyoxal) by aldehyde dehydrogenase and aldehyde oxidase, respectively. Glycolic acid is 

oxidized to glyoxylic acid by glycolic acid oxidase or lactic dehydrogenase. Glyoxylic acid can be 

metabolized to formate, glycine, or malate, all of which may be further broken down to generate 

respiratory CO2, or to oxalic acid, which is excreted in the urine. In excess, oxalic acid can form calcium 

oxalate crystals. Rate-limiting steps in the metabolism of ethylene glycol include the initial formation of 

glycolaldehyde and the conversion of glycolic acid to glyoxylic acid, both of which are saturable 

processes. The conversion of glycolic acid to glyoxylic acid is the most rate-limiting step in ethylene 

glycol metabolism (Slikker et al. 2004). 

Both glycolic acid and oxalic acid are found in the blood and urine of unexposed individuals as a result of 

normal metabolism of proteins and carbohydrates (NTP-CERHR 2004). The ranges of background levels 

of glycolic acid are 0.0044–0.0329 mM (plasma) and 0.075–0.790 mM (urine) (NTP-CERHR 2004). For 

oxalic acid, the background ranges are 0.002–0.0233 mM (plasma) and 0.086–0.444 mM (urine) (NTPCERHR 2004). 

In volunteers who inhaled 13C-ethylene glycol for 4 hours, glycolic acid concentrations in the plasma 

peaked at about 4–5 hours after the commencement of exposure (Carstens et al. 2003). About 1% of the 

estimated dose of 0.96–1.51 mg/kg was excreted in the urine as glycolic acid, and 0.08–0.28% was 

excreted as oxalic acid over 30 hours. Expired CO2 was not measured in this study. Similar results were 

obtained for two other similarly exposed volunteers (Upadhyay et al. 2008). 

Plasma glycolate levels of 12.2 and 15.4 mmol/L were reported upon hospital admission of an infant 

female and an adult male, respectively, with ethylene glycol intoxication after oral exposure (Hewlett et 

al. 1986). The infant survived, while the adult male died, probably due to delayed treatment. In a case 
 

ETHYLENE GLYCOL 124 

3. HEALTH EFFECTS 

Figure 3-3. Metabolic Pathway for Ethylene Glycol 

HO	 C C OH
 H2 H2
 

Ethylene glycol 

Lactate NAD * Alcohol 

dehydrogenase 

O Pyruvate NADH 

HO C C 

H2 

H 

Glucose Glycoaldehyde O O

NAD C C 

Krebs cycle Aldehyde H H dehydrogenase 

Glyoxal 

NADH O 

HO C C 

H2 OH O 

H C OH CO Glycolic acid 2 

Formate 

** 

Glycolate oxidase or 

lactate dehydrogenase 

O O

C C 

H OH 

Glyoxylic acid 

O 

H2N C C

O O	 H2 OH
 

Malate
 C C

Glycine HO OH 

Oxalic acid Acetate 

CO2 and other metabolites 

Calcium oxalate 

*Rate-limiting step 

**Most rate-limiting step 

Sources: NTP-CERHR 2004; Slikker et al. 2004 
 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 125 

3. HEALTH EFFECTS 

report of six adult male patients with ethylene glycol intoxication, one of whom died, plasma glycolate 

levels on admission ranged from 17.0 to 29.3 mmol/L (Jacobsen et al. 1984). 

Glycolic acid was the major metabolite in the plasma of male rats exposed orally to single gavage doses 

of 10, 100, or 1,000 mg/kg 14C-ethylene glycol (Frantz et al. 1989, 1996c). During the first 12 hours after 

dosing, no oxalate was detected in the plasma at any dose, but glyoxylate and glyoxal, as well as trace 

amounts of glycoaldehyde, were detected in plasma samples from the lower dose groups (100 and 

1,000 mg/kg). In the 10 mg/kg group, glyoxylate levels exceeded glycolate levels throughout the 

12 hours postdosing. 

In rats given 2,000 mg/kg ethylene glycol by gavage, peak plasma levels of ethylene glycol occurred 

2 hours after administration, while plasma glycolate levels peaked 6 hours after dosing (Hewlett et al. 

1989). Dogs receiving 1,000 or 1,360 mg/kg ethylene glycol by gavage exhibited peak plasma ethylene 

glycol levels at 2 hours after dosing and peak plasma glycolate levels 4 hours after dosing (Hewlett et al. 

1989). 

Carney et al. (2001) showed that enzymes metabolizing glycolate are more quickly saturated with bolus 

subcutaneous dosing than with slow, continuous dosing (i.e., via infusion pump), leading to higher peak 

plasma glycolate levels (~3–10-fold higher) with bolus dosing. This study demonstrates the importance 

of dose rate on the dose at which glycolic acid metabolism is saturated. 

In vivo studies in rats and mice show increasing urinary excretion (as a percent of dose) of glycolic acid 

and other metabolites with increasing dose, probably corresponding to saturation of glycolic acid 

metabolism. In male rats exposed to 10 or 1,000 mg/kg 14C-ethylene glycol via gavage, most of the 

urinary radioactivity consisted of unmetabolized ethylene glycol at the low dose (>90% of urinary 

radioactivity) (Frantz et al. 1996c). At the high dose, glycolic acid comprised 25% of the urinary 

radioactivity in the first 12 hours after dosing and 37% during the following 12 hours. Oxalic acid was 

detected in the urine sample from the 12–24-hour interval, accounting for 7.4% of the urinary 

radioactivity in that sample (Frantz et al. 1989, 1996c). The urinary metabolite pattern was similar in 

female rats treated at these doses (Frantz et al. 1989, 1996b). In mice exposed orally to 10, 100, 200, 400, 

or 1,000 mg/kg 14C-ethylene glycol, the proportion of urinary radioactivity excreted as ethylene glycol or 

glycolate also varied with dose, with increasing excretion of glycolate at higher doses (Frantz et al. 1991, 

1996b). No other metabolites were detected in mouse urine after oral doses. 
 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 126 

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In both rats and mice exposed percutaneously to 10 or 1,000 mg/kg (rats) or 100 or 1,000 mg/kg (mice) 

undiluted 14C ethylene glycol, or 1,000 mg/kg 50% aqueous solution, most of the urinary radioactivity 

was excreted as ethylene glycol (Frantz et al. 1989, 1991, 1996b, 1996c). In rats, 87–100% of the urinary 

radioactivity apparently was parent compound, regardless of dermal dose. In mice, glycolate represented 

a greater proportion of urinary radioactivity after exposure to 1,000 mg/kg of 50% ethylene glycol (up to 

20% in the 12–24-hour interval). 

Urinary excretion of ethylene glycol and glycolate accounted for 20.7 and 4.5% (respectively) of a 

2,000 mg/kg dose of ethylene glycol in rats over the course of 24 hours post-dosing (Hewlett et al. 1989). 

Male Porton rats receiving 1,000–1,110 mg/kg ethylene glycol in the drinking water for 21 days had 

urinary oxalate levels equivalent to 1.18% conversion of ethylene glycol to oxalate; rats given diets 

supplemented with 30 or 60% sucrose (administered to evaluate the role of carbohydrates in calcium 

oxalate crystal formation) excreted oxalate equivalent to 1.11 and 0.7% conversion of ethylene glycol, 

respectively (Rofe et al. 1986). 

Corley and Soelberg (2005) evaluated levels of ethylene glycol, glycolic acid, and oxalate in the blood, 

urine, and/or kidneys of male Wistar rats treated with ethylene glycol doses up to 400 mg/kg/day for 

12 months. In the kidneys, levels of glycolic acid and oxalate did not differ from controls at doses up to 

150 mg/kg/day, but at levels ≥300 mg/kg/day, concentrations were substantially higher than controls and 

increased with dose. Levels of oxalate in the kidneys of rats exposed to 400 mg/kg/day averaged 

18,800 μg/g, with large interindividual variability. Similar results were observed with glycolic acid in 

blood, with no difference from control at doses up to 150 mg/kg/day but 3.3-fold higher concentrations in 

rats dosed with 300 mg/kg/day. Ethylene glycol was excreted in the urine at levels proportional to dose 

across all doses tested. A disproportionate increase in urinary excretion of glycolic acid occurred at 

300 mg/kg/day, suggesting that the metabolism of glycolic acid is saturated at doses between 150 and 

300 mg/kg/day in male Wistar rats. Oxalate concentrations in blood and urine were similar across all 

doses, reflecting the low solubility of this compound in physiological fluids (Corley and Soelberg 2005). 

In vitro data suggest that humans may metabolize glycolic acid at a higher rate than do rats. In vitro 

metabolism studies using liver homogenates from female humans and Sprague-Dawley rats generated 

Vmax/Km estimates of 2.16 and 0.68 L/hour/g for humans and rats, respectively (Corley et al. 2005). 

Booth et al. (2004) reported Vmax/Km values of 0.43 and 0.28 L/hour/g (humans and rats, respectively) 

from a study using human and rat liver slices. 
 

 

 

 

 

 

 

 

 

 

 

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3.4.4 Elimination and Excretion 

Little information is available on the elimination of ethylene glycol in humans; most of the elimination 

data are from humans accidentally poisoned and given therapeutic treatments to reduce the metabolism of 

ethylene glycol or extract it from the blood. In laboratory animals treated with 14C-ethylene glycol, the 

primary routes of excretion are exhaled air and urine, regardless of the route of exposure. After oral 

exposure, saturation of metabolic pathways at higher doses leads to a shift in excretory pattern, with 

greater urinary excretion (and corresponding decreases in elimination via expired air) at higher doses. 

3.4.4.1 Inhalation Exposure 

Carstens et al. (2003) evaluated the urinary excretion of ethylene glycol and its two primary metabolites 

(glycolic and oxalic acids) in two volunteers who inhaled 13C-ethylene glycol at doses estimated by the 

authors to be 0.96 and 1.51 mg/kg. Urinary excretion of 13C-ethylene glycol up to 30 hours after exposure 

constituted 6.4–9.3% of the inhaled dose, while 13C-glycolic acid and 13C-oxalic acid together comprised 

1–2% of the inhaled dose. However, the dose estimates are highly uncertain, as they were calculated by 

estimating the loss of 13C-ethylene glycol from an inhalation vessel in which the compound was 

“warmed”. Air concentrations to which the volunteers were exposed were not measured, and the 

warming temperature was not reported. The authors reported that 13C-ethylene glycol was not detectable 

in exhaled air, but did not assess expiration of 13CO2. Similar results were obtained for two other 

similarly exposed volunteers (Upadhyay et al. 2008). 

In rats, the major route of elimination for inhaled ethylene glycol is expiration of CO2. Rats exposed for 

30 minutes to 14C-ethylene glycol vapor (32 mg/m3

) or for 17 minutes to 14C-ethylene glycol aerosol 

(184 mg/m3

) excreted 63% (over 4 days) and 75% (over 6 days), respectively, of the initial body burden 

as 14CO2 (Marshall and Cheng 1983). Urinary excretion constituted 20 and 12% of the initial body 

burden after vapor and aerosol exposures, respectively, while fecal excretion was 3% and 1% (Marshall 

and Cheng 1983). 

3.4.4.2 Oral Exposure 

In untreated adults, the serum half-life has been estimated to be between 3.0 and 8.4 hours (Jacobsen et al. 

1988; Peterson et al. 1981). In a series of 19 patients, the mean half-life of ethylene glycol during a 

period without ADH inhibitor treatment and without dialysis was 8.6 hours, while elimination after 

fomepizole therapy was slower, with a half-life of 19.7 hours (Sivilotti et al. 2000). In another study, the 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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half-life of ethylene glycol during fomepizole therapy was 11–14.75 hours (Baud et al. 1988). The 

approximate serum half-life of ethylene glycol was 1.5–3.0 hours in a child treated with hemodialysis and 

mannitol therapy (Rothman et al. 1986), and 2.7 hours in an adult male during hemodialysis and 

intravenous ethanol treatment (Cheng et al. 1987). As these half-lives indicate, the rate of ethylene glycol 

elimination is greatly increased by dialysis. 

In laboratory animals, the elimination half-lives for ethylene glycol in the plasma have been estimated at 

1.4–2.5 hours in rats given between 10 and 2,000 mg/kg; 0.3–1.1 hours in mice given doses between 

10 and 1,000 mg/kg; 3.5 hours in dogs given 1,000–1,360 mg/kg; and 2.7–3.7 hours in monkeys given 

1,110 mg/kg (Frantz et al. 1989, 1991, 1996a, 1996c; Hewlett et al. 1989; McChesney et al. 1971). The 

plasma elimination half-life for ethylene glycol was similar (1.4–1.7 hours) in pregnant rats treated with 

single oral doses of 10 or 2,500 mg/kg on Gd 10 (Pottenger et al. 2001). Data from intravenous 

administration of ethylene glycol show similar elimination half-lives (Frantz et al. 1989, 1991, 1996a, 

1996c; Martis et al. 1982). 

Frantz et al. (1989, 1991, 1996b, 1996c) treated rats and mice with single oral doses of 14C-ethylene 

glycol between 10 and 1,000 mg/kg and measured radioactivity in exhaled air, excreta, tissues, and 

carcass up to 96 hours after exposure. Table 3-7 shows the disposition of radioactivity. In male and 

female rats, the major excretory routes were via CO2 exhalation (27–48% of the administered 

radioactivity) and urinary elimination (21–43%); 2–4% was excreted via the feces (Frantz et al. 1989, 

1996b, 1996c). Female mice showed a similar profile when exposed over the same dose range, exhaling 

22–55% of the dose as CO2 and 3–11% as exhaled volatile organic compounds (VOCs), while excreting 

24–56% in the urine and 5–16% in the feces (Frantz et al. 1991, 1996b). In mice, the majority of the 

exhaled radioactivity was eliminated during the first 12 hours after dosing (Frantz et al. 1991, 1996b). 

Both mice and rats exhibited a dose-dependent shift in excretory patterns, as shown in the data in 

Table 3-7. An increase in urinary excretion of radioactivity was evident between 10 and 100 mg/kg in 

female mice, between 10 and 400 mg/kg in female rats, and between 800 and 1,000 mg/kg in male rats. 

In its review of these data, NTP-CERHR (2004) noted that the increased urinary excretion of radioactivity 

probably resulted from saturation of the enzymes that metabolize glycolic acid, leading to increased 

excretion of this metabolite in the urine. Pottenger et al. (2001) provided data on urinary levels of 

ethylene glycol and glycolate in female rats exposed to doses of 10–2,500 mg/kg that confirmed the 

saturation of glycolic acid metabolism in the dose range between 150 and 500 mg/kg. 
 

 

 

 

 

 

 

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Table 3-7. Radioactivity (Percent of Administered Dose) in Excreta 96 Hours 

After Oral or Exposure to 14C-Ethylene Glycol
 

10 mg/kg 400 mg/kg 600 mg/kg 800 mg/kg 1,000 mg/kg 

Female rats 

Expired CO2 47.9±0.8a 39.4±1.0 32.8±3.4 32.1±2.3 28.2±2.1 

Urine 25.5±3.8 38.0±7.6 37.1±17.0 41.0±5.1 35.0±13.2 

Feces 2.8±0.8 NA NA NA 4.4±3.4 

Tissues 5.7±0.5 NA NA NA 2.2±0.4 

Carcass 9.6±1.2 NA NA NA 4.2±0.1 

Total recoveryb 91.8±3.4 NA NA NA 83.3±3.5 

Male rats 

Expired CO2 42.2±0.3 38.77±0.85 34.00±1.5 30.12±2.13 27.3±1.4 

Urine 26.2±2.1 20.52±9.44 25.78±10.25 26.69±6.41 42.7±7.1 

Feces 2.9±0.6 NA NA NA 2.4±0.8 

Tissues 10.1±1.1 NA NA NA 4.8±2.2 

Carcass 11.6±1.1 NA NA NA 5.0±0.5 

Total recoveryc 93.4±2.1 NA NA NA 83.2±7.2 

Female mice 

Expired CO2 55.4±10.2 42.3±2.7 31.4±5.5 26.1±5.3 21.6±1.7 

Exhaled VOCs 3.1±2.0 2.5±0.7 3.8±1.5 11.5±3.8 4.2±1.2 

Urine 23.6±12.1 43.0±3.4 43.6±13.1 44.8±10.4 55.7±10.9 

Feces 6.6±4.1 4.5±1.5 10.9±4.2 16.2±9.8 3.7±0.8 

Tissues 3.6±1.1 2.3±0.9 1.3±0.3 1.1±0.7 0.8±0.2 

Carcass 7.2±2.0 5.0±1.4 3.7±0.8 4.2±1.6 2.6±0.3 

Total recoveryd 102.1±12.9 100.1±1.6 96.4±3.8 106.7±7.6 94.1±6.6 

a

Mean±standard deviation from groups of four animals

b

Cage wash accounted for 0.3–9%
 c

Cage wash accounted for 0.3–1% d

Cage wash accounted for 0.5–6%
 

CO2 = carbon dioxide; NA = not applicable; VOCs = volatile organic compounds
 

Source: Frantz et al. 1996b, 1996c 
 

 

 

 

 

 

 

 

 

 

 

 

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Monkeys given a single oral dose of 1 mL/kg 14C-ethylene glycol (equivalent to 1,110 mg/kg) excreted 

about 24% of the administered dose as unchanged parent compound in the urine within 48 hours 

(McChesney et al. 1971). In dogs, approximately 50% of an oral dose of ethylene glycol (173 mmol/kg) 

was excreted via the urine within 72 hours after exposure (Grauer et al. 1987). 

3.4.4.3 Dermal Exposure 

13C-Glycolytic acid was detected in the urine of three volunteers following 4- or 6-hour dermal exposure 

to 13C-ethylene glycol (Upadhyay et al. 2008). 

Rats and mice were treated with dermal application of doses of 10–1,000 mg/kg undiluted 14C-ethylene 

glycol or 1,000 mg/kg 50% aqueous solution of 14C-ethylene glycol under occlusion for 6 hours, and 

radioactivity was measured in expired air, excreta, tissues, remaining carcass, and occlusion materials and 

skin (unabsorbed dose) for 96 hours after dosing (Frantz et al. 1989, 1991, 1996b, 1996c). Table 3-6 

shows the disposition of radioactivity. In male and female rats, 6–14% of the administered dose was 

expired, while 4–8% was excreted in the urine, and ~1% was recovered from the feces (Frantz et al. 1989, 

1996b, 1996c). In female mice treated similarly (except with a low dose of 100 mg/kg undiluted ethylene 

glycol), most of the administered dose was recovered as exhaled volatile organic compounds (21–34%) or 

CO2 (10–16%) (Frantz et al. 1991, 1996b). Urine and feces each accounted for another 5–12% of the 

dose (Frantz et al. 1991, 1996b). No dose-related shift in excretory patterns was observed in either 

species, suggesting that metabolic pathways were not saturated under the slower absorption conditions 

observed with dermal exposure. 

3.4.5 Physiologically Based Pharmacokinetic (PBPK)/Pharmacodynamic (PD) Models 

Physiologically based pharmacokinetic (PBPK) models use mathematical descriptions of the uptake and 

disposition of chemical substances to quantitatively describe the relationships among critical biological 

processes (Krishnan et al. 1994). PBPK models are also called biologically based tissue dosimetry 

models. PBPK models are increasingly used in risk assessments, primarily to predict the concentration of 

potentially toxic moieties of a chemical that will be delivered to any given target tissue following various 

combinations of route, dose level, and test species (Clewell and Andersen 1985). Physiologically based 

pharmacodynamic (PBPD) models use mathematical descriptions of the dose-response function to 

quantitatively describe the relationship between target tissue dose and toxic end points. 
 

 

 

 

 

 

 

 

 

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PBPK/PD models refine our understanding of complex quantitative dose behaviors by helping to 

delineate and characterize the relationships between: (1) the external/exposure concentration and target 

tissue dose of the toxic moiety, and (2) the target tissue dose and observed responses (Andersen and 

Krishnan 1994; Andersen et al. 1987). These models are biologically and mechanistically based and can 

be used to extrapolate the pharmacokinetic behavior of chemical substances from high to low dose, from 

route to route, between species, and between subpopulations within a species. The biological basis of 

PBPK models results in more meaningful extrapolations than those generated with the more conventional 

use of uncertainty factors. 

The PBPK model for a chemical substance is developed in four interconnected steps: (1) model 

representation, (2) model parameterization, (3) model simulation, and (4) model validation (Krishnan and 

Andersen 1994). In the early 1990s, validated PBPK models were developed for a number of 

toxicologically important chemical substances, both volatile and nonvolatile (Krishnan and Andersen 

1994; Leung 1993). PBPK models for a particular substance require estimates of the chemical substancespecific physicochemical parameters, and species-specific physiological and biological parameters. The 

numerical estimates of these model parameters are incorporated within a set of differential and algebraic 

equations that describe the pharmacokinetic processes. Solving these differential and algebraic equations 

provides the predictions of tissue dose. Computers then provide process simulations based on these 

solutions. 

The structure and mathematical expressions used in PBPK models significantly simplify the true 

complexities of biological systems. If the uptake and disposition of the chemical substance(s) are 

adequately described, however, this simplification is desirable because data are often unavailable for 

many biological processes. A simplified scheme reduces the magnitude of cumulative uncertainty. The 

adequacy of the model is, therefore, of great importance, and model validation is essential to the use of 

PBPK models in risk assessment. 

PBPK models improve the pharmacokinetic extrapolations used in risk assessments that identify the 

maximal (i.e., the safe) levels for human exposure to chemical substances (Andersen and Krishnan 1994). 

PBPK models provide a scientifically sound means to predict the target tissue dose of chemicals in 

humans who are exposed to environmental levels (for example, levels that might occur at hazardous waste 

sites) based on the results of studies where doses were higher or were administered in different species. 

Figure 3-4 shows a conceptualized representation of a PBPK model. 
 

ETHYLENE GLYCOL 132 

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Figure 3-4. Conceptual Representation of a Physiologically Based
 

Pharmacokinetic (PBPK) Model for a Hypothetical
 

Chemical Substance
 

Inhaled c hem ic al E x ha led c hem ic al 

Inges tion 

Lungs 

Liv er 

V m a x GI K m T ra c t A 

V R 

E F at T 

N E 

O R 

U I S lo w ly S perfus ed A 

tis s ues L 

R ic h ly B perfus ed L B tis s ues O L F ec es O O 

D O K idney D 

U rin e

S k in 

 C h e m ic a ls 

contacting skin 

Note: This is a conceptual representation of a physiologically based pharmacokinetic (PBPK) model for a 

hypothetical chemical substance. The chemical substance is shown to be absorbed via the skin, by inhalation, or by 

ingestion, metabolized in the liver, and excreted in the urine or by exhalation. 

Source: adapted from Krishnan and Andersen 1994 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 133 

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If PBPK models for ethylene glycol exist, the overall results and individual models are discussed in this 

section in terms of their use in risk assessment, tissue dosimetry, and dose, route, and species 

extrapolations. 

A PBPK model is available to describe the disposition of ethylene glycol and its intermediate metabolite, 

glycolic acid, in rats and humans after inhalation, oral consumption, intraperitoneal injection, intravenous 

injection, or subcutaneous infusion of ethylene glycol or glycolic acid (Corley et al. 2005). The model is 

composed of submodels for ethylene glycol and glycolic acid, which are linked via saturable metabolism 

in the liver. The submodel for ethylene glycol consists of eight compartments connected by blood flow 

(lungs, richly perfused tissues, poorly perfused tissues, fat, skin, gastrointestinal tract, liver, and kidney); 

the submodel for glycolic acid has a similar structure except that the lung is included in the richly 

perfused tissue group. Gastrointestinal tract, lung, and skin were included separately in order to permit 

simulation of different exposure routes. The model assumes instantaneous dispersion of ethylene glycol 

and glycolic acid through each compartment based on blood perfusion rates and relative tissue:blood 

partition coefficients. Urinary elimination of ethylene glycol and glycolic acid were modeled. 

Physiological parameters used in the model are shown in Table 3-8. Tissue volumes were scaled to body 

weight; alveolar ventilation and cardiac output were scaled as (body weight)0.75; blood flows were scaled 

to cardiac output; and kidney parameters (glomerular filtration, tubule urine volume, and urine 

production) were scaled as a fraction of kidney weights. Partition coefficients used in the model are given 

in Table 3-9. Blood:air partition coefficients were measured in vitro using human and female SpragueDawley rat blood; tissue:blood coefficients were measured in rats, and human partition coefficients were 

assumed to equal those of rats. 

A simplified metabolic pathway simulating metabolism of ethylene glycol to glycolic acid and from 

glycolic acid to glyoxylic acid (the rate-limiting steps) with saturable Michaelis-Menten kinetics was used 

in the model. Metabolic rate constants were estimated from in vitro data. The elimination of ethylene 

glycol into urine was described as a first-order clearance of arterial blood scalable by (body weight)0.70 . 

Urinary elimination of glycolic acid was initially simulated as a first-order equation, but was modified to 

allow for reabsorption of glycolic acid in the renal tubules by a saturable Michaelis-Menten-like process 

in order to better predict elimination of this metabolite at low doses (<200 mg/kg). Table 3-9 shows the 

metabolic and renal elimination parameters used in the study. 
 

 

 

 

 

 

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Table 3-8. Physiological Parameters in PBPK Models for Ethylene Glycol 

Parameter SD rat Human 

Physiologic parameters 

Body weight (kg) 0.23 60 

Tissue volumes (fraction of body weight) 

Blood 0.059 0.059 

Liver 0.034 0.0314 

Kidneys 0.007 0.0044 

Lungs 0.005 0.0115 

Gastrointestinal tract 0.05 0.034 

Fat 0.07 0.231 

Skin 0.19 0.051 

Richly perfused 0.0423 0.0371 

Slowly perfused 0.91, sum other tissues 

Flows (liter/hour/kg) 

Cardiac output 15 15 

Alveolar ventilation 15 15 

Blood flows (fraction of cardiac output) 

Liver 0.18 0.25 

Gastrointestinal tract 0.15 0.21 

Kidney 0.141 0.25 

Fat 0.07 0.05 

Skin 0.058 0.03 

Richly perfused 1.0, sum other tissues 

Slowly perfused 0.17 0.17 

Source: Corley et al. 2005 
 

 

 

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Table 3-9. Biochemical Parameters in PBPK Models for Ethylene Glycol 

Ethylene glycol Glycolic acid 

Parameter SD rat Human SD Rat Human 

Absorption rate (hour-1) 

Oral gavage 1–5 1 1 1 

Subcutaneous 1 - 1 -

Intraperitoneal 1 - - -

Partition coefficients 

Blood:air 17,901 17,542 - -

Blood:saline 1.14 1.14 3.36 3.36 

Skin:saline 1.36 1.36 2.51 2.51 

Skin:air 17,901 17,542 - -

Liver:blood 0.96 0.96 0.97 0.97 

Kidney:blood 1.22 1.22 1.40 1.40 

Lung:blood 0.96 0.96 - -

Fat:blood 0.64 0.64 1.09 1.09 

Skin:blood 1.19 1.19 0.75 0.75 

Gastrointestinal tract:blood 1.48 1.48 0.95 0.95 

Richly perfused:blood 0.96 0.96 0.97 0.97 

Slowly perfused:blood 0.67 0.67 0.70 0.70 

Elimination (L/hour/kg) 

Urinary clearance 0.06 0.06 0.06 (alternate 0.06 (alternate 

model) model) 

SD = Sprague-Dawley 

Source: Corley et al. 2005 
 

 

 

 

 

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The model was validated against several pharmacokinetic studies in rats and humans (Corley and 

McMartin 2005; Corley et al. 2005). In the examples reported by Corley et al. (2005), the model 

predictions provided reasonably good fit to measured plasma concentrations of ethylene glycol and 

glycolic acid after oral exposure to ethylene glycol in female Sprague-Dawley rats and intraperitoneal 

exposure to male Wistar rats, although predictions of glycolic acid concentrations after low-dose 

(10 mg/kg) oral exposure were not as reliable. The authors suggested that differences in analytical 

methods used to measure glycolic acid in the dataset used to determine model parameters and the 

validation dataset may have contributed to the less reliable prediction after low-dose exposure. 

Validation against human data was complicated by the need to incorporate effects of therapeutic 

interventions on blood levels of ethylene glycol and glycolic acid in humans acutely poisoned with 

ethylene glycol. With modifications to simulate these effects, the model provided reasonably good 

predictions of blood levels reported in several clinical case reports over a broad range of oral doses 

(Corley and McMartin 2005). 

Using the model for humans, Corley et al. (2005) estimated that the threshold glycolic acid concentration 

for developmental effects in rodents (considered by the authors to be a peak of 2 mM) would only be 

reached in human females ingesting doses of 350 mg/kg (assuming a 58-kg female). However, the model 

was not calibrated to pregnancy, and it is not clear whether physiological and/or biochemical changes that 

could affect ethylene glycol toxicokinetics might occur during pregnancy (NTP-CERHR 2004). 

Furthermore, uncertainty in the glycolic acid saturation concentration in humans somewhat limits the 

usefulness of this model for predicting developmental toxicity in human embryos. 

Data from a single study (Pottenger et al. 2001) suggested that pregnancy status did not affect the time 

course of ethylene glycol, glycolic acid, or oxalic acid pharmacokinetics in maternal blood and urine 

(including peak concentration, time of peak concentration, area under the concentration vs. time curve, or 

elimination half-time) when groups of pregnant and nonpregnant rats were treated by gavage with doses 

of 10 or 2,500 mg/kg ethylene glycol (pregnant rats treated on Gd 10). While Gd 10 is a sensitive time 

point for developmental effects, NTP-CERHR (2004) observed that pregnancy-related changes in 

metabolism would not be captured in this study due to the narrow exposure window. In their review, 

NTP-CERHR (2004) noted that there were no data to assess whether maternal levels of enzymes involved 

in ethylene glycol metabolism might change over the course of gestation. In addition, the study measured 

maternal, not fetal, levels of ethylene glycol and its metabolites. However, Corley et al. (2002) showed 

that levels of glycolic acid in rat embryos and extraembryonic fluid paralleled those of maternal blood, 

albeit at levels 1.4–4-fold higher than maternal levels. Slikker et al. (2004) reported that there are 
 

 

 

 

 

 

 

 

 

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species-specific differences in the transfer of glycolic acid from maternal blood to conceptus. Likewise, 

fetal and/or placental differences in expression of enzymes metabolizing ethylene glycol and glycolic acid 

over the course of gestation may affect local concentrations of glycolic acid to which the developing 

conceptus is exposed, yet little is known about these differences (NTP-CERHR 2004). In particular, there 

are no data on the ontogeny of glycolate oxidase (the enzyme that breaks down glycolic acid) expression 

in rodent or human embryos (NTP-CERHR 2004). 

Additional data are needed to reduce uncertainty in the saturation concentration of glycolic acid in 

humans, and such data may alter the model predictions of peak glycolic acid concentrations in humans 

exposed to ethylene glycol. Although in vitro data suggest that humans may metabolize glycolic acid 

more efficiently than rats, based on comparisons of apparent Vmax/Km values obtained using liver 

homogenates and liver slices, there are no in vivo human data with which to predict the saturation point in 

humans (NTP-CERHR 2004). 

As identified in Section 3.12.3 (Ongoing Studies), Corley and coworkers are working to extend the PBPK 

model for ethylene glycol and glycolic acid in rats and humans (Corley et al. 2005) to include glyoxylic 

acid and oxalic acid. However, at the time of publication of this ATSDR update Toxicological Profile for 

Ethylene Glycol, the model revisions had not been completed. 

3.5 MECHANISMS OF ACTION 

3.5.1 Pharmacokinetic Mechanisms 

Absorption. No studies investigating the mechanism by which ethylene glycol is absorbed from the 

lung, gastrointestinal tract, or skin were located. 

Distribution. As discussed in more detail in Section 3.4.2, there are limited data on the distribution of 

ethylene glycol after inhalation exposure. Studies in rats, mice, and monkeys, as well as limited data in 

humans, suggest that ethylene glycol is distributed according to total body water (Frantz et al. 1989, 1991, 

1996b, 1996c; Jacobsen et al. 1988). There are no data on the sites of ethylene glycol metabolism or on 

the distribution of its primary metabolite (glycolic acid) in the body. The inverted yolk sac placenta, 

which develops in both mice and rats, tends to concentrate weak acids such as glycolic acid; neither 

humans nor rabbits develop a yolk sac placenta, and a preliminary study showed that glycolic acid does 

not concentrate in rabbit embryonic fluids (NTP-CERHR 2004). Corley et al. (2002) confirmed that the 

rat embryo and embryonic fluid concentrate glycolic acid, reaching levels roughly 2–4-fold higher than 
 

 

 

 

 

 

 

 

 

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maternal blood. No additional data are available to characterize the mechanisms by which ethylene 

glycol is transported to the kidneys or developing fetus, the primary sites of toxic action. 

Metabolism. As discussed in more detail in Section 3.4.3, ethylene glycol metabolism has been well 

characterized. Glycolic acid has been identified as the primary metabolite and putative developmental 

toxicant associated with ethylene glycol exposure, while a downstream metabolite (oxalate) is associated 

with renal toxicity. There are no data on the tissues most responsible for metabolism of ethylene glycol. 

Two of the primary enzymes involved in ethylene glycol metabolism (alcohol dehydrogenase and 

aldehyde dehydrogenase) are also responsible for ethanol metabolism, and ethanol metabolism largely 

takes place in the liver. Thus, it is likely that the liver is also the primary site of ethylene glycol 

metabolism; however, other tissues, including the placenta, also produce these enzymes. Pharmacokinetic 

parameters (e.g., plasma half-life, area under the curve, and peak ethylene glycol concentration) are 

similar after both oral and intravenous exposure (Frantz et al. 1989, 1991, 1996a, 1996b, 1996c), 

indicating that a first-pass effect, if any, has a negligible effect on the toxicokinetics. 

Excretion. As discussed in more detail in Section 3.4.4, studies in mice and rats of ethylene glycol 

excretion after oral, dermal, and intravenous exposure indicate that ethylene glycol is principally excreted 

as expired CO2 and as both parent compound and glycolic acid in the urine (Frantz et al. 1989, 1991, 

1996b, 1996c). At higher doses, oxalate was also excreted at measurable levels. 

3.5.2 Mechanisms of Toxicity 

There are three main effects responsible for the toxicity of ethylene glycol: increased osmolal gap, 

metabolic acidosis, and formation of calcium oxalate crystals. Several lines of evidence suggest that 

metabolites of ethylene glycol (Figure 3-3) are responsible for these effects. First, there is a latent period 

before the symptoms of acidosis appear; second, there is no correlation between observed toxicity and 

ethylene glycol blood concentration; and third, inhibition of ethylene glycol oxidation prevents toxicity 

(Jacobsen and McMartin 1986). 

In the initial stages after ingestion (there are no reports of clinical toxicity in humans following inhalation 

or dermal exposure), the ethylene glycol concentration in extracellular fluids increases, leading to 

increased osmolality. This increased osmolality (hyperosmolarity) causes increased osmolal gap, one of 

the hallmarks of ethylene glycol intoxication. Osmolal gap is defined as a difference between the 

measured and calculated osmolality. Osmolality (calculated) can be estimated from the formula that takes 
 

 

 

 

 

 

 

 

 

 

 

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into account normal serum concentrations of sodium, glucose, and BUN. This calculated osmolality is 

then compared to the serum osmolality measured following ethylene glycol ingestion; a difference 

>10 indicates an increased osmolal gap (Fligner et al. 1985). The increased osmolal gap is not specific to 

ethylene glycol intoxication and can occur when any unmeasured, osmotically active, low molecular 

weight solute (e.g., methanol or ethanol) is present in the serum. In dogs given oral doses of 

10,743 mg/kg ethylene glycol, serum osmolality peaked (460 milliosmoles/kg) at 3–6 hours, and the 

osmolal gap peaked (134 milliosmoles/kg) at 3 hours, coinciding with peak serum ethylene glycol levels 

at 3 hours (Grauer et al. 1984). In these animals, the anion gap was also significantly increased at 3 hours 

(19 Meq/L). 

The second characteristic of ethylene glycol intoxication is metabolic acidosis. Ethylene glycol itself has 

low toxicity (Godolphin et al. 1980; Jacobsen and McMartin 1986), but it is metabolized to a variety of 

toxic metabolites such as glycolaldehyde, glycolic acid (glycolate), glyoxylic acid (glyoxylate), and 

oxalic acid (oxalate) (Jacobsen et al. 1988; Parry and Wallach 1974; Vale 1979; Wiener and Richardson 

1988). In general, the accumulation of acids leads to acidosis, a state that is characterized by actual or 

relative decrease of alkali in body fluids in relation to the acid content. In the case of ethylene glycol, 

metabolic processes that follow ethylene glycol ingestion lead to the accumulation of glycolic and lactic 

acids resulting in metabolic acidosis. Glycolic acid is the most abundant ethylene glycol metabolite 

(Jacobsen et al. 1984). Following ingestion of high doses of ethylene glycol, glycolic acid tends to 

accumulate as a result of metabolic saturation. The accumulation of metabolites such as glycolic acid and 

oxalate, as well as lactic acid formed through the reduction of NAD, leads to an increased serum anion 

gap (the difference between the sum of the measured cations and anions) and metabolic acidosis, which 

are responsible for toxicity observed after ethylene glycol exposure. While lactate levels increase in some 

human cases up to 5–7 mmol (Jacobsen et al. 1984, 1988; Parry and Wallach 1974), glycolate levels 

range up to 20–25 mmol, thus accounting for a greater portion of the anion gap. Glycolic acid accounts 

for approximately 96% of the anion gap in ethylene glycol-poisoned patients (Gabow et al. 1986; 

Jacobsen et al. 1984). In dogs given oral doses of 10,743 mg/kg ethylene glycol, the anion gap was 

significantly increased at 3 hours (19 Meq/L) coinciding with peak serum ethylene glycol levels (Grauer 

et al. 1984). The maximum production of metabolites occurs 6–12 hours after ethylene glycol ingestion 

and coincides with development of respiratory and cardiovascular symptoms. 

Nephrotoxicity and neurotoxicity can follow because oxalate can produce renal and brain damage as it 

chelates with calcium ions forming insoluble calcium oxalate monohydrate crystals, another characteristic 

of ethylene glycol poisoning (Jacobsen et al. 1988). Glycolic acid accumulation and metabolic acidosis 
 

 

 

 

 

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do not contribute to renal toxicity, which is solely caused by oxalate crystal accumulation (Cruzan et al. 

2004; Green et al. 2005). Oxalate crystal formation may lead to hypocalcemia and imbalance of serum 

divalent ion concentrations (Zeiss et al. 1989). Recent in vitro studies confirm that intracellular calcium 

oxalate, not the oxalate ion, is responsible for cytotoxicity observed in cultured human proximal tubule 

cells (Guo and McMartin 2005; Guo et al. 2007). Results of studies using isolated rat kidney 

mitochondria indicate that calcium oxalate, not oxalate ion, induces changes in mitochondrial 

permeability, which may lead to renal cell death (McMartin and Wallace 2005). 

Although the mechanism of ethylene glycol neurotoxicity is not completely understood, the available 

information on humans suggests that it occurs in two stages, an early one (30 minutes to 12 hours after 

exposure) and a late one (several days after exposure). The early-stage symptoms are due to the direct 

toxicity of ethylene glycol, while the late-stage neurotoxicity is due to metabolic acidosis caused by the 

accumulation of ethylene glycol metabolites, primarily glycolic acid, which leads to metabolic acidosis. 

Additional evidence for this late neurotoxicity is crystalline deposits of calcium oxalate in the walls of 

small blood vessels found in the brain of humans who died of acute ethylene glycol poisoning (Froberg et 

al. 2006; Zeiss et al. 1989). Similar effects were observed in rats fed 2,500 mg/kg/day ethylene glycol for 

13 weeks (Melnick 1984). The role of calcium in ethylene-glycol-induced neurotoxicity is not known but 

the formation of calcium oxalate crystals may cause perturbation of intracellular calcium homeostasis 

causing membrane abnormalities generally associated with cell injury and cell death. A generalized soft 

tissue mineralization that included the heart (vessels and muscle), lungs (interstitial), stomach, and 

vascular system occurred in male F344 rats exposed to 1,000 mg/kg/day in the diet for 1 year (DePass et 

al. 1986a; Woodside 1982). These histopathological changes may be the result of altered calcium 

metabolism (Rajagopal et al. 1977). Other effects of ethylene glycol metabolites include inhibition of 

oxidative phosphorylation, respiration, glucose metabolism, protein synthesis, DNA replication, 

ribosomal ribonucleic acid (RNA) synthesis, central nervous system respiration, and serotonin 

metabolism (Vale 1979). 

The presented data indicate that glycolic acid is the major toxic metabolite contributing to metabolic 

acidosis, which is a primary cause of systemic toxicity following exposure to ethylene glycol. Glycolic 

acid has also been identified as the proximate cause of developmental effects observed with ethylene 

glycol exposure (NTP-CERHR 2004; Slikker et al. 2004). A number of mechanistic studies have ruled 

out both ethylene glycol itself and other metabolites as the primary developmental toxicants, while 

metabolic acidosis was shown to interact with glycolic acid at high doses to enhance developmental 

effects. The available data suggest that peak concentrations in the range of 2–3 mM glycolic acid are 
 

 

 

 

 

 

 

 

 

 

 

 

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necessary for developmental toxicity to occur in rodents (Carney et al. 2001; Corley et al. 2002; NTPCERHR 2004; Slikker et al. 2004). 

Klug et al. (2001) compared the effects of several ethylene glycol metabolites on rat whole embryos 

(Gd 9.5) in culture, observing that only glycolic acid affected embryonic development at metabolite 

concentrations observed in in vivo studies of ethylene glycol. Ethylene glycol and other metabolites did 

not affect development except at much higher concentrations than have been seen in vivo. 

Using rat whole embryos (Gd 10) exposed to either ethylene glycol or glycolic acid for 46 hours in vitro, 

Carney et al. (1996) showed that ethylene glycol concentrations up to 50 mM did not cause 

morphological changes, while glycolic acid caused changes in the skeletal and craniofacial regions at 

concentrations ≥12 mM. These changes are consistent with the dysmorphogenesis observed in rats after 

in vivo exposure to ethylene glycol. In the same study, the role of medium acidification in the observed 

effects was investigated by comparing the effects of 12.5 mM glycolic acid (pH 6.7), 12.5 mM sodium 

glycolate (pH 7.4), and control medium (pH 7.4 or 6.7) on rat whole embryos in culture. The incidence of 

affected embryos was 67% in the glycolic acid group, 58% in the sodium glycolate group, 8% in the 

pH 6.7 controls, and 0% in the pH 7.4 controls. The authors concluded that glycolic acid was the primary 

developmental toxicant, and that medium acidification was a minor contributor to the observed effects. 

In vivo studies have shown similar results. When glycolic acid was administered to CD rats via gavage 

on Gd 6–15, the observed effects on offspring were similar to those observed after ethylene glycol 

exposure (Munley et al. 1999). In an effort to determine the extent to which metabolic acidosis 

contributed to the developmental effects induced by glycolic acid, Carney et al. (1999) treated time-mated 

Sprague-Dawley rats with ethylene glycol (2,500 mg/kg) or glycolic acid (650 mg/kg) via gavage or 

sodium glycolate via subcutaneous injection on Gd 6–15. Metabolic acidosis was induced in both the 

ethylene glycol and glycolic acid groups, but not in the sodium glycolate treatment group. Upon sacrifice 

on Gd 21, fetal body weights were decreased and malformations were increased in all three groups, 

indicating that glycolate was capable of inducing effects in the absence of metabolic acidosis. The 

authors reported that developmental toxicity was enhanced by an interaction between metabolic acidosis 

and glycolate at high doses (Carney et al. 1999). 
 

 

 

 

 

 

 

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3.5.3 Animal-to-Human Extrapolations 

Toxicokinetic and mechanistic data suggest that humans may be less sensitive than rodents to systemic 

and developmental effects of ingested ethylene glycol. In vitro studies by Corley et al. (2005) and Booth 

et al. (2004) found that human liver tissue was more effective than liver tissue from rats and rabbits in 

metabolizing glycolic acid to glyoxylic acid, suggesting that humans are less likely to accumulate glycolic 

acid (the proximate developmental toxicant). In addition, NTP-CERHR (2004) reviewed preliminary data 

by Carney and coworkers indicating that the inverted yolk sac placenta, a stage in placental development 

that does not exist in humans or rabbits, tends to concentrate weak acids such as glycolic acid in the 

embryonic fluids. Corley et al. (2002) confirmed that the rat embryo and embryonic fluid concentrate 

glycolic acid, reaching levels roughly 2–4-fold higher than maternal blood. These data suggest enhanced 

sensitivity to ethylene glycol developmental effects in rodents compared with humans. 

3.6 TOXICITIES MEDIATED THROUGH THE NEUROENDOCRINE AXIS 

Recently, attention has focused on the potential hazardous effects of certain chemicals on the endocrine 

system because of the ability of these chemicals to mimic or block endogenous hormones. Chemicals 

with this type of activity are most commonly referred to as endocrine disruptors. However, appropriate 

terminology to describe such effects remains controversial. The terminology endocrine disruptors, 

initially used by Thomas and Colborn (1992), was also used in 1996 when Congress mandated the EPA to 

develop a screening program for “...certain substances [which] may have an effect produced by a 

naturally occurring estrogen, or other such endocrine effect[s]...”. To meet this mandate, EPA convened a 

panel called the Endocrine Disruptors Screening and Testing Advisory Committee (EDSTAC), and in 

1998, the EDSTAC completed its deliberations and made recommendations to EPA concerning endocrine 

disruptors. In 1999, the National Academy of Sciences released a report that referred to these same types 

of chemicals as hormonally active agents. The terminology endocrine modulators has also been used to 

convey the fact that effects caused by such chemicals may not necessarily be adverse. Many scientists 

agree that chemicals with the ability to disrupt or modulate the endocrine system are a potential threat to 

the health of humans, aquatic animals, and wildlife. However, others think that endocrine-active 

chemicals do not pose a significant health risk, particularly in view of the fact that hormone mimics exist 

in the natural environment. Examples of natural hormone mimics are the isoflavinoid phytoestrogens 

(Adlercreutz 1995; Livingston 1978; Mayr et al. 1992). These chemicals are derived from plants and are 

similar in structure and action to endogenous estrogen. Although the public health significance and 

descriptive terminology of substances capable of affecting the endocrine system remains controversial, 

scientists agree that these chemicals may affect the synthesis, secretion, transport, binding, action, or 
 

 

 

 

 

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elimination of natural hormones in the body responsible for maintaining homeostasis, reproduction, 

development, and/or behavior (EPA 1997). Stated differently, such compounds may cause toxicities that 

are mediated through the neuroendocrine axis. As a result, these chemicals may play a role in altering, 

for example, metabolic, sexual, immune, and neurobehavioral function. Such chemicals are also thought 

to be involved in inducing breast, testicular, and prostate cancers, as well as endometriosis (Berger 1994; 

Giwercman et al. 1993; Hoel et al. 1992). 

Insufficient information is available to adequately assess the endocrine disruptor potential of ethylene 

glycol. No studies were located regarding endocrine disruption in humans after exposure to ethylene 

glycol. 

No histopathological changes occurred in endocrine organs of rats or mice in acute-, intermediate- and 

chronic-duration oral studies of ethylene glycol. As discussed in the Endocrine Effects subsection of 

Section 3.2.2.2, histological examinations in these studies included the adrenals, pancreas, pituitary, 

thyroid, and/or parathyroids (Blood 1965; DePass et al. 1986a; Hong et al. 1988; Melnick 1984; NTP 

1993; Robinson et al. 1990; Schladt et al. 1998; Woodside 1982). Assessments of endocrine function 

(e.g., hormone levels) were not conducted in these or other studies of ethylene glycol. 

Reproductive toxicity studies showed that oral exposure to high doses of ethylene glycol affected fertility 

and fetal viability in mice and rats (Harris et al. 1992; Lamb et al. 1985; Morrissey et al. 1989; NTP 1986; 

Price et al. 1985; Schuler et al. 1984), and possibly male reproductive function in mice (Morrissey et al. 

1989; NTP 1986) and gestational duration in rats (NTP 1988). 

Ethylene glycol had no estrogenic or antiestrogenic activity in an in vitro MVLN cell-based 

transactivation assay (Freyberger and Schmuck 2005). MVLN cells constitutively express the estrogen 

receptor (ER) and are stably transfected with the luciferase reporter gene and the corresponding hormone 

responsive element derived from the Xenopus Vitellogenin A2 gene. Evaluations included cytotoxicity 

and luciferase gene expression in the absence and presence of estradiol stimulation, as well as ER-α 

binding affinity. 

3.7 CHILDREN’S SUSCEPTIBILITY 

This section discusses potential health effects from exposures during the period from conception to 

maturity at 18 years of age in humans, when all biological systems will have fully developed. Potential 
 

 

 

 

 

 

 

 

 

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effects on offspring resulting from exposures of parental germ cells are considered, as well as any indirect 

effects on the fetus and neonate resulting from maternal exposure during gestation and lactation. 

Relevant animal and in vitro models are also discussed.
 

Children are not small adults. They differ from adults in their exposures and may differ in their
 

susceptibility to hazardous chemicals. Children’s unique physiology and behavior can influence the
 

extent of their exposure. Exposures of children are discussed in Section 6.6, Exposures of Children.
 

Children sometimes differ from adults in their susceptibility to hazardous chemicals, but whether there is 

a difference depends on the chemical (Guzelian et al. 1992; NRC 1993). Children may be more or less
 

susceptible than adults to health effects, and the relationship may change with developmental age 

(Guzelian et al. 1992; NRC 1993). Vulnerability often depends on developmental stage. There are
 

critical periods of structural and functional development during both prenatal and postnatal life, and a
 

particular structure or function will be most sensitive to disruption during its critical period(s). Damage 

may not be evident until a later stage of development. There are often differences in pharmacokinetics 

and metabolism between children and adults. For example, absorption may be different in neonates 

because of the immaturity of their gastrointestinal tract and their larger skin surface area in proportion to 

body weight (Morselli et al. 1980; NRC 1993); the gastrointestinal absorption of lead is greatest in infants
 

and young children (Ziegler et al. 1978). Distribution of xenobiotics may be different; for example, 

infants have a larger proportion of their bodies as extracellular water, and their brains and livers are 

proportionately larger (Altman and Dittmer 1974; Fomon 1966; Fomon et al. 1982; Owen and Brozek
 

1966; Widdowson and Dickerson 1964). The infant also has an immature blood-brain barrier (Adinolfi
 

1985; Johanson 1980) and probably an immature blood-testis barrier (Setchell and Waites 1975). Many
 

xenobiotic metabolizing enzymes have distinctive developmental patterns. At various stages of growth 

and development, levels of particular enzymes may be higher or lower than those of adults, and 

sometimes unique enzymes may exist at particular developmental stages (Komori et al. 1990; Leeder and
 

Kearns 1997; NRC 1993; Vieira et al. 1996). Whether differences in xenobiotic metabolism make the
 

child more or less susceptible also depends on whether the relevant enzymes are involved in activation of
 

the parent compound to its toxic form or in detoxification. There may also be differences in excretion, 

particularly in newborns who all have a low glomerular filtration rate and have not developed efficient
 

tubular secretion and resorption capacities (Altman and Dittmer 1974; NRC 1993; West et al. 1948). 

Children and adults may differ in their capacity to repair damage from chemical insults. Children also 

have a longer remaining lifetime in which to express damage from chemicals; this potential is particularly
 

relevant to cancer.
 
 

 

 

 

 

 

 

 

 

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Certain characteristics of the developing human may increase exposure or susceptibility, whereas others 

may decrease susceptibility to the same chemical. For example, although infants breathe more air per 

kilogram of body weight than adults breathe, this difference might be somewhat counterbalanced by their 

alveoli being less developed, which results in a disproportionately smaller surface area for alveolar 

absorption (NRC 1993). 

Young children are susceptible to ethylene glycol poisoning through the accidental ingestion of antifreeze 

because it is a brightly colored, sweet tasting liquid that can be mistaken for a beverage (Leth and 

Gregersen 2005). Many ethylene glycol poisonings occur when an antifreeze bottle is in use or when 

antifreeze is not kept in its original container (e.g., if it is poured into a cup or soft drink bottle), because 

children can ingest ethylene glycol from an accessible open container (EPA 2004b; Leth and Gregersen 

2005). Children also may play in a puddle of antifreeze that has been spilled or drained onto the ground. 

Children and adolescents comprise a significant percentage of ethylene glycol acute intoxications from 

accidental or intentional ingestion. For example, in a total of 735 exposures voluntarily reported to U.S. 

poison control centers in 2003, 150 (20%) were younger than 19 years old and 84 (11%) were younger 

than 6 years old (Watson et al. 2004). Similarly, of 751 total exposures reported in 2005, 167 (22%) were 

≤19 years old and 69 (9%) were younger than 6 years old (Lai et al. 2006). It has been reported that 

ingestion of as little as 10–15 mL ethylene glycol can be fatal in small children (White and Liebelt 2006). 

A limited amount of information on health effects of ethylene glycol in children is available from several 

case reports of patients admitted to hospitals for treatment of acute oral poisoning. A 4-year-old girl 

(14 kg) who accidentally ingested an unknown amount of antifreeze containing 41% ethylene glycol 

vomited and was admitted to a hospital 4 hours later, where drowsiness, hypotonia, and metabolic 

acidosis subsequently developed (Harry et al. 1998). A 13-year-old girl (80 kg) who intentionally 

ingested approximately 4 fluid ounces of antifreeze (ethylene glycol concentration not reported) was 

brought to a hospital approximately 30 minutes after ingestion with no evidence of intoxication, but 

subsequently developed ataxia, dysarthria, metabolic acidosis, and oxalate crystals in the urine (Boyer et 

al. 2001). An 8-month-old boy (7.7 kg) who drank up to 120 mL ethylene glycol (95%) was taken to a 

hospital where he appeared lethargic; metabolic acidosis, increased osmolal gap, and oxalate crystals in 

the urine were detected 3–4 hours post-ingestion (Baum et al. 1999). Six children ranging in age from 

22 months to 14 years were admitted to a hospital for treatment of ethylene glycol poisoning over a 4-year 

period (Caravati et al. 2004). Four of the children (7–13 years old, 22–50 kg) ingested between 30 and 

120 mL (alleged doses) of antifreeze (ethylene glycol concentration not reported); the amounts ingested 
 

 

 

 

 

 

 

 

 

 

 

 

 

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by the other two children were unknown. Presenting symptoms included dizziness, slurred speech, 

nausea, ataxia, and lethargy. Varying degrees of metabolic acidosis were also observed, but renal 

function was normal. 

The effects in the pediatric patients summarized above are largely consistent with the first stage of 

ethylene glycol poisoning in adults (e.g., central nervous system depression, metabolic changes, 

gastrointestinal upset). Treatment with fomepizole (4-methylpyrazole), alone or in combination with 

other methods (see Section 3.11, Methods for Reducing Toxic Effects), generally mitigated the 

progression of the clinical course to the second and third stages of ethylene glycol poisoning (pronounced 

metabolic acidosis, cardiopulmonary compromise, and renal insufficiency) and led to full recovery. The 

case reports are consistent with an expectation that health effects in children and adults are similar. 

Although there are no known differences in the toxicity of ethylene glycol between adults and children, 

there is no evidence to substantiate the presumption. There is no evidence to indicate that children are 

likely to be exposed to higher (or lower) amounts of ethylene glycol from everyday living, suggesting that 

children are perhaps equally at risk for non-accidental or non-intentional exposure and potential toxic side 

effects. 

Information on the developmental toxicity of ethylene glycol is available from oral, inhalation, and 

dermal studies in rats, mice, and rabbits. Oral studies in animals have identified the developing fetus as 

the most sensitive target for acute-duration exposure to ethylene glycol. Gavage exposure of rats and 

mice to ethylene glycol during gestation results in a consistent pattern of developmental effects including 

reduced fetal body weight and increases in malformations, particularly axial skeletal malformations 

(Neeper-Bradley 1990; Neeper-Bradley et al. 1995; Price et al. 1985). No teratogenic effects were 

observed in rabbits orally exposed during gestation (Tyl et al. 1993). Results of inhalation developmental 

studies in rats and mice are generally consistent with the oral findings, but are confounded by concurrent 

oral exposure (Tyl 1985, 1988a; Tyl et al. 1995a, 1995b). A single study of dermal exposure to ethylene 

glycol in pregnant mice did not indicate developmental effects (Tyl 1988b; Tyl et al. 1995c). 

Developmental effects of intermediate-duration oral exposure to ethylene glycol in animals include 

decreased body weight and kidney effects in offspring. In mice exposed via drinking water in a 

continuous breeding assay, pup body weights were reduced in both F1 and F2 generations (Morrissey et al. 

1989; NTP 1986). Effects on postnatal kidney weight were observed in pups of rats exposed by gavage 

for 15 days during gestation (NTP 1988). In a three-generation dietary study in rats, no effects on 

gestation survival or pup body weight through postnatal day 21 were observed in F1 or F2 pups (DePass et 
 

 

 

 

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al. 1986b). The available animal data are insufficient for determining whether postnatal developmental 

toxicity is a potential concern in exposed children. Effects of ethylene glycol on the immune and 

endocrine systems have not been adequately studied. Ethylene glycol did not induce dominant lethal 

mutations in orally-exposed rats (DePass et al. 1986b) and was consistently negative in in vitro 

genotoxicity assays in a variety of test systems, indicating that it is unlikely to affect DNA in parental 

germ cells. 

No studies are available that describe potential differences in the toxicokinetics or the mechanism of 

action of ethylene glycol in children. As discussed in Section 3.5.2, Mechanisms of Toxicity, glycolic 

acid is the major toxic metabolite contributing to metabolic acidosis, which is a primary cause of systemic 

toxicity in children as well as adults following exposure to ethylene glycol. Glycolic acid has also been 

identified as the proximate cause of the developmental effects in animals observed with ethylene glycol 

exposure (NTP-CERHR 2004; Slikker et al. 2004). 

Ethylene glycol metabolism is known to involve alcohol dehydrogenase and aldehyde dehydrogenase, 

and may also involve cytochrome P450 isozymes (NTP-CERHR 2004). Polymorphisms in the genes 

encoding these enzymes may lead to wide variability in the production and elimination of glycolic acid 

and other metabolites in humans exposed to ethylene glycol, but data quantifying the range of variability 

are not currently available (NTP-CERHR 2004). In addition, fetal and/or placental differences in 

expression of these enzymes over the course of gestation will affect local concentrations of glycolic acid 

and other metabolites to which the developing conceptus is exposed, yet little is known about these 

differences (NTP-CERHR 2004). 

A PBPK model for ethylene glycol in adult humans has been developed and has been used to estimate 

that the threshold glycolic acid concentration for developmental effects in rodents would only be reached 

in human females ingesting doses of 350 mg/kg (assuming a 58-kg female) (Corley et al. 2005). 

However, the model was not calibrated to pregnancy, and it is not clear whether physiological and/or 

biochemical changes that could affect ethylene glycol toxicokinetics might occur during pregnancy. No 

models are available for children or lactating women. A PBPK model has also been developed for rats 

(Corley et al. 2005), but there is no model for mice, which are more sensitive than rats to ethylene glycol 

developmental toxicity. Biomonitoring data for children, including levels of ethylene glycol in placental 

tissue, cord blood, neonatal blood, meconium fluid, or breast milk, have not been located. 
 

 

 

 

 

 

 

 

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3.8 BIOMARKERS OF EXPOSURE AND EFFECT 

Biomarkers are broadly defined as indicators signaling events in biologic systems or samples. They have 

been classified as markers of exposure, markers of effect, and markers of susceptibility (NAS/NRC 

1989). 

A biomarker of exposure is a xenobiotic substance or its metabolite(s) or the product of an interaction 

between a xenobiotic agent and some target molecule(s) or cell(s) that is measured within a compartment 

of an organism (NAS/NRC 1989). The preferred biomarkers of exposure are generally the substance 

itself, substance-specific metabolites in readily obtainable body fluid(s), or excreta. However, several 

factors can confound the use and interpretation of biomarkers of exposure. The body burden of a 

substance may be the result of exposures from more than one source. The substance being measured may 

be a metabolite of another xenobiotic substance (e.g., high urinary levels of phenol can result from 

exposure to several different aromatic compounds). Depending on the properties of the substance (e.g., 

biologic half-life) and environmental conditions (e.g., duration and route of exposure), the substance and 

all of its metabolites may have left the body by the time samples can be taken. It may be difficult to 

identify individuals exposed to hazardous substances that are commonly found in body tissues and fluids 

(e.g., essential mineral nutrients such as copper, zinc, and selenium). Biomarkers of exposure to ethylene 

glycol are discussed in Section 3.8.1. 

Biomarkers of effect are defined as any measurable biochemical, physiologic, or other alteration within an 

organism that, depending on magnitude, can be recognized as an established or potential health 

impairment or disease (NAS/NRC 1989). This definition encompasses biochemical or cellular signals of 

tissue dysfunction (e.g., increased liver enzyme activity or pathologic changes in female genital epithelial 

cells), as well as physiologic signs of dysfunction such as increased blood pressure or decreased lung 

capacity. Note that these markers are not often substance specific. They also may not be directly 

adverse, but can indicate potential health impairment (e.g., DNA adducts). Biomarkers of effects caused 

by ethylene glycol are discussed in Section 3.8.2. 

A biomarker of susceptibility is an indicator of an inherent or acquired limitation of an organism's ability 

to respond to the challenge of exposure to a specific xenobiotic substance. It can be an intrinsic genetic or 

other characteristic or a preexisting disease that results in an increase in absorbed dose, a decrease in the 

biologically effective dose, or a target tissue response. If biomarkers of susceptibility exist, they are 

discussed in Section 3.10, Populations That Are Unusually Susceptible. 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

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3.8.1 Biomarkers Used to Identify or Quantify Exposure to Ethylene Glycol 

The presence of parent compound in the blood and urine serves as the only biomarker of exposure that is 

specific to ethylene glycol. The half-life of ethylene glycol in plasma is estimated to be 3–7 hours in 

laboratory animals (Marshall 1982; Winek et al. 1978). Available human data indicate a similar half-life 

for ethylene glycol in human plasma (Eder et al. 1998). The elimination half-life of ethylene glycol in the 

urine of acutely intoxicated humans ranges from 3.0 to 8.4 hours (Jacobsen et al. 1988; Peterson et al. 

1981). Based on the relatively short half-life in the blood and urine, the presence of parent compound 

would serve as a reliable biomarker of exposure only within the first day following exposure. Rapid 

methods for determining ethylene glycol in serum and urine are available for use in the clinical setting 

(Aarstad et al. 1993; Blandford and Desjardins 1994), but may not always be readily available in 

emergency situations. 

Other biomarkers of exposure are typically used in conjunction with serum and urinary ethylene glycol 

levels to assist in confirmation and quantitation of ethylene glycol intoxication. For example, levels of 

glycolic, lactic, and oxalic acid metabolites of ethylene glycol may be useful indicators of ethylene 

glycol-induced toxicity. However, these other biomarkers are not specific to ethylene glycol. As 

discussed in detail in Section 3.4, ethylene glycol is rapidly metabolized to glycolic acid, which 

accumulates in the blood and causes metabolic acidosis (Gabow et al. 1986; Jacobsen et al. 1984). 

Glycolic acid blood levels have been more closely correlated to clinical symptoms than ethylene glycol 

blood levels (Hewlett et al. 1986). Due to the rapid formation of glycolic acid in the body and its 

correlation to clinical symptoms of ethylene glycol poisoning, measurements of both parent compound 

and glycolic acid levels are important in diagnosis and treatment (Hess et al. 2004). Although glycolate is 

not a specific biomarker for ethylene glycol exposure (because it is an endogenous chemical that can also 

be obtained from the diet), an increase in plasma glycolate above the general background level (<1 mM) 

is a good indication of ethylene glycol exposure (McMartin 2007). It is particularly useful in situations 

where there is a lengthy period between exposure and blood sampling; in these situations, there is often 

no ethylene glycol in the plasma (due to its metabolism and elimination), whereas there still are elevated 

levels of glycolate. Only a few clinical toxicology laboratories routinely offer glycolic acid analyses 

(Hess et al. 2004; Pellegrino et al. 2006). Lactic acid may contribute to metabolic acidosis, whereas 

oxalic acid forms calcium oxalate crystals that are considered to be the cause of ethylene glycol-induced 

nephrotoxicity (Jacobsen and McMartin 1986; Moossavi et al. 2003; Pellegrino et al. 2006; Wiley 1999). 
 

 

 

 

 

 

 

 

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Metabolic acidosis with increased serum anion and osmolal gaps are suggestive of ethylene glycol 

poisoning, but do not provide a specific diagnosis. Serum anion gap is calculated from concentrations of 

sodium, chloride, and bicarbonate, is normally 12–16 mM, and is elevated after ethylene glycol ingestion 

(Chung and Tuso 1989; Factor and Lava 1987; Heckerling 1987; Hess et al. 2004; Spillane et al. 1991; 

Zeiss et al. 1989). The increase in the anion gap correlates with the elevation in plasma glycolate levels 

(Hess et al. 2004; Jacobsen et al. 1984). Osmolal gap represents the difference between the measured and 

calculated osmolalities and is also elevated during ethylene glycol intoxication. As unmetabolized 

ethylene glycol accounts for most of the osmolality gap, it is only raised in the initial stages of toxicity, 

and decreases later as anion gap increases due to metabolism of the parent compound to acidic 

intermediates (Hess et al. 2004; Leth and Gregersen 2005). The normal value for osmolal gap in humans 

is 10–15 mOsm/kg water (Egbert and Abraham 1999; Leth and Gregersen 2005; Scalley et al. 2002). 

Normal osmolality gap does not exclude ethylene glycol poisoning, although an elevated osmolality gap 

is suggestive (Leth and Gregersen 2005). 

The presence of calcium oxalate monohydrate crystals is an indicator of possible ethylene glycol 

intoxication, although not specific to ethylene glycol. The crystals can be found in renal tubules and/or 

urine after exposure to relatively large amounts of ethylene glycol (CDC 1987; Chung and Tuso 1989; 

Factor and Lava 1987; Godolphin et al. 1980; Heckerling 1987; Parry and Wallach 1974; Rothman et al. 

1986; Siew et al. 1975a; Underwood and Bennett 1973). 

3.8.2 Biomarkers Used to Characterize Effects Caused by Ethylene Glycol 

Biomarkers of effects exist for ethylene glycol poisoning, but none are specific to ethylene glycol. These 

include clinical manifestations of nervous system, cardiopulmonary toxicity, renal toxicity, and laboratory 

findings of metabolic acidosis and calcium oxalate crystalluria. 

Clinical manifestations progress in three main stages, although the course may vary between individuals. 

Signs of central nervous system toxicity appear within 0.5–12 hours following acute ingestion exposure 

and include ataxia, slurred speech, nystagmus, semiconsciousness, unresponsiveness, and somnolence 

that can culminate in convulsions and coma (CDC 1987; Cheng et al. 1987; Chung and Tuso 1989; Factor 

and Lava 1987; Hess et al. 2004; Leth and Gregersen 2005; Parry and Wallach 1974; Rothman et al. 

1986; Spillane et al. 1991; Underwood and Bennett 1973; Zeiss et al. 1989). Neurological manifestations 

suggestive of cranial nerve damage, including facial paralysis and impaired vision, may appear in 

survivors as late as 1–2 weeks after an acute exposure to ethylene glycol (Chung and Tuso 1989; Factor 
 

 

 

 

 

 

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and Lava 1987; Lewis et al. 1997; Mallya et al. 1986; Spillane et al. 1991). Cardiopulmonary 

manifestations, including respiratory distress and congestive heart failure, generally develop after 12– 

24 hours and usually in patients with coma; signs include tachycardia, dyspnea, tachypnea, hypertension, 

and pulmonary edema (Godolphin et al. 1980; Hess et al. 2004; Leth and Gregersen 2005; Parry and 

Wallach 1974; Siew et al. 1975a; Vale 1979; Zeiss et al. 1989). Renal failure occurs 24–72 hours after 

ingestion with clinical manifestations that include flank pain, hematuria, proteinuria, or anuria (Leth and 

Gregersen 2005). 

Metabolic acidosis occurs approximately 12–24 hours following ethylene glycol ingestion, results from 

accumulation of acid metabolites (primarily glycolic acid), and is characterized by pronounced serum 

osmolal and anion gaps (Hess et al. 2004; Leth and Gregersen 2005). Serum osmolality is determined 

from the concentrations of sodium, urea nitrogen, and glucose, and increased osmolality (osmolal gap) 

suggests the presence of unmeasured osmotically active substances such as ethylene glycol, methanol, 

ethanol, or acetone (Eder et al. 1998; Hoffman et al. 1993). As ethylene glycol is metabolized, the 

osmolal gap is decreased and the anion gap (the difference between the sum of the measured cations and 

anions) is increased (Jacobsen et al. 1988). Organic acids increase the anion gap; glycolic acid accounts 

for approximately 96% of the anion gap in ethylene glycol-poisoned patients (Gabow et al. 1986; 

Jacobsen et al. 1984). 

Calcium oxalate crystals in the urine can appear 4–8 hours after ethylene glycol ingestion, and deposition 

of calcium oxalate monohydrate crystals in the renal tubules can subsequently result in nephropathy and 

eventual renal failure 24–72 hours after ingestion (CDC 1987; Chung and Tuso 1989; Factor and Lava 

1987; Godolphin et al. 1980; Heckerling 1987; Jacobsen et al. 1988; Leth and Gregersen 2005; Parry and 

Wallach 1974; Rothman et al. 1986; Siew et al. 1975a; Underwood and Bennett 1973). Two forms of 

oxalate crystals may be found in the urine; the monohydrate form is an elongated crystal, and the 

anydrous form is octahedral (pyramid in shape). Renal toxicity can also be indicated by increased serum 

levels of BUN or creatinine (Grauer et al. 1987). 

For more information on biomarkers for renal effects of chemicals see ATSDR/CDC Subcommittee Report 

on Biological Indicators of Organ Damage (Agency for Toxic Substances and Disease Registry 1990) 

and for information on biomarkers for neurological effects see OTA (1990). 
 

 

 

 

 

 

 

 

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3.9 INTERACTIONS WITH OTHER CHEMICALS 

Information regarding the influence of other chemicals on the toxicity of ethylene glycol comes from case 

studies describing treatment after accidental or intentional ingestion of ethylene glycol. The toxic effects 

of ethylene glycol result from its metabolic conversion by alcohol dehydrogenase into glycolic acid, 

which is further metabolized to oxalate. The formation of oxalate crystals is associated with renal toxicity 

encountered after exposure to ethylene glycol. Administration of ethanol, 4-methyl pyrazole, or 

1,3-butanediol reduces or eliminates ethylene glycol toxicity. This is accomplished by the following 

mechanisms: (1) ethanol, which is also metabolized by alcohol dehydrogenase, competes with ethylene 

glycol for the enzyme, thus preventing the formation of potentially toxic ethylene glycol metabolites; 

(2) 4-methyl pyrazole inhibits the activity of alcohol dehydrogenase (Baud et al. 1987, 1988); and 

(3) 1,3-butanediol is also a competitive inhibitor of ethylene glycol biotransformation and reduces the 

formation of glycolic acid (Hewlett et al. 1983). Therefore, ethanol, 4-methyl pyrazole, and 

1,3-butanediol reduce the toxicity of ethylene glycol by interacting with or inhibiting the activity of 

alcohol dehydrogenase, thus reducing the amount of glycolic acid and oxalate formed. 

Magnesium and vitamin B6 were found to affect the toxicity of ethylene glycol in animals. In rats, 

vitamin B6 accelerates the oxidation of glyoxylate to carbon dioxide rather than to oxalate (Gershoff and 

Andrus 1962). Vitamin B6 deficiency can cause inhibition of ethylene glycol's oxidation to carbon 

dioxide and thus cause an increase in ethylene glycol toxicity. Magnesium may prevent renal deposition 

of calcium oxalate by altering solvent characteristics of oxalate in urine (Browning 1965; Gershoff and 

Andrus 1962; Khan et al. 1993). 

3.10 POPULATIONS THAT ARE UNUSUALLY SUSCEPTIBLE 

A susceptible population will exhibit a different or enhanced response to ethylene glycol than will most 

persons exposed to the same level of ethylene glycol in the environment. Reasons may include genetic 

makeup, age, health and nutritional status, and exposure to other toxic substances (e.g., cigarette smoke). 

These parameters result in reduced detoxification or excretion of ethylene glycol, or compromised 

function of organs affected by ethylene glycol. Populations who are at greater risk due to their unusually 

high exposure to ethylene glycol are discussed in Section 6.7, Populations with Potentially High 

Exposures. 

Individuals deficient in vitamin B6 could be more sensitive to toxic effects of ethylene glycol because 

vitamin B6 may increase the accumulation of toxic metabolites (Browning 1965; Gershoff and Andrus 
 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 153 

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1962). Similarly, magnesium deficiency appears to encourage calcium oxalate deposition in the renal 

tubules, especially in the presence of high calcium levels (Ebisuno et al. 1987). Thus, individuals who are 

deficient in magnesium and/or ingest high levels of calcium may be more sensitive to the toxic effects of 

ethylene glycol. 

3.11 METHODS FOR REDUCING TOXIC EFFECTS 

This section will describe clinical practice and research concerning methods for reducing toxic effects of 

exposure to ethylene glycol. However, because some of the treatments discussed may be experimental 

and unproven, this section should not be used as a guide for treatment of exposures to ethylene glycol. 

When specific exposures have occurred, poison control centers and medical toxicologists should be 

consulted for medical advice. The following texts provide specific information about treatment following 

exposures to ethylene glycol: 

Egbert PA, Abraham K. 1999. Ethylene glycol intoxication: Pathophysiology, diagnosis, and 

emergency management. ANNA J 26(3):295-300. 

Ellenhorn MJ, Schonwald S, Ordog G, et al, eds. 1997. Ellenhorn's medical toxicology. Diagnosis and 

treatment of human poisoning. Baltimore, MD: Williams & Wilkins, 1152-1156. 

Jolliff HA, Sivilotti MLA. 2004. Ethylene glycol. In: Dart RC, ed. Medical toxicology. 3rd. ed. 

Philadelphia, PA: Lippicott Williams & Wilkins, 1223-1230. 

Mégarbane B, Borron SW, Baud FJ. 2005. Current recommendations for treatment of severe toxic 

alcohol poisonings. Intensive Care Med 31(2):189-195. 

Scalley RD, Ferguson DR, Piccaro JC, et al. 2002. Treatment of ethylene glycol poisoning. Am Fam 

Physician 66(5):807-812. 

White ML, Liebelt EL. 2006. Update on antidotes for pediatric poisoning. Pediatr Emerg Care 

22(11):740-749. 

Wiener SW. 2006. Toxic alcohols. In: Flomenbaum NE, Goldfrank LR, Hoffman RS, et al., eds. 

Goldfrank's toxicologic emergenices. New York, NY: McGraw-Hill Companies, Inc., 1447-1459. 

3.11.1 Reducing Peak Absorption Following Exposure 

No studies were found describing methods to reduce peak absorption of ethylene glycol after inhalation 

exposure. After oral exposure, nasogastric lavage may be of benefit in reducing absorption, but only if 

performed within 1–2 hours following ingestion (Barceloux et al. 1999; Egbert and Abraham 1999; Leth 

and Gregersen 2005; Wiley 1999). Activated charcoal is only partially effective at preventing 
 

 

 

 

 

 

 

 

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gastrointestinal absorption of ethylene glycol because large amounts are needed to bind relatively small 

amounts of ethylene glycol, and the therapeutic window for this action is less than an hour (Scalley et al. 

2002). The degree to which activated charcoal may lower absorption of ethylene glycol of may adsorb its 

toxic metabolites by entero-enteric dialysis is not known (Wiley 1999). Administration of syrup of ipecac 

for gastric emptying is strongly contraindicated due to the potential for altered mental status, seizures, and 

cardiac dysrhythmias, which may occur abruptly in ethylene glycol poisoning (Barceloux et al. 1999; 

Leth and Gregersen 2005; Wiley 1999). Dermal absorption can be minimized through washing the skin 

with soap to remove any existing ethylene glycol. Copious irrigation with water or saline can aid in 

ocular decontamination. 

3.11.2 Reducing Body Burden 

Clinical procedures for treating ethylene glycol poisoning focus on reduction of the body burden of 

ethylene glycol and its toxic metabolites, interference with toxic metabolite formation (which results in 

increased urinary excretion of parent compound), increased elimination of toxic metabolites produced, 

reduction of metabolic acidosis, and prevention of kidney failure. Procedures include administration of 

antidotes (ethanol or fomepizole), intravenous bicarbonate and hydration for profound acidemia, and 

hemodialysis for refractory acidosis (Barceloux et al. 1999; Egbert and Abraham 1999; Gardner et al. 

2004; Leth and Gregersen 2005; Scalley et al. 2002). 

Antidotes for ethylene glycol include the alcohol dehydrogenase inhibitors, ethanol and fomepizole, 

which act to decrease the alcohol dehydrogenase-catalyzed metabolism of ethylene glycol, thus 

effectively increasing the urinary excretion of ethylene glycol. Ethanol competes with ethylene glycol for 

alcohol dehydrogenase receptor sites and fomepizole acts as a potent inhibitor of alcohol dehydrogenase 

(Barceloux et al. 1999; Egbert and Abraham 1999; Gardner et al. 2004; Leth and Gregersen 2005). 

Antidotal therapy is indicated if ethylene glycol blood levels exceed 200 mg/L (Gardner et al. 2004). 

Hemodialysis (see below) may be avoided if patients are diagnosed and treated with fomepizole or 

ethanol early in the course of poisoning. 

Fomepizole treatment has repeatedly been demonstrated to be a particularly effective therapy for ethylene 

glycol poisoning and is the preferred treatment/antidote in adults and children (Amathieu et al. 2006; 

Boyer et al. 2001; Caravati et al. 2004; Harry et al. 1998; Pizon and Brooks 2006; Scalley et al. 2002; 

White and Liebelt 2006). When compared with ethanol, the advantages of fomepizole include a slower 

rate of excretion by the kidneys, lack of central nervous system depression and hypoglycemia (which are 
 

 

 

 

 

 

ETHYLENE GLYCOL 155 

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major hazards of ethanol therapy in children), and easier maintenance of effective plasma levels (Scalley 

et al. 2002), indicating that ethanol should only be used if fomepizole is not available. The standard 

treatment regimen for fomepizole in adult and pediatric patients is an intravenous loading dose of 

15 mg/kg followed by maintenance dosing of 10 mg/kg intravenous every 12 hours for four doses 

(Scalley et al. 2002; White and Liebelt 2006). Subsequent doses (if needed) are 15 mg/kg intravenous 

every 12 hours until plasma ethylene glycol level has been reduced below 20 mg/dL. 

Intravenous fluid administration may be initiated early to increase urine output, which effectively 

increases the excretion of ethylene glycol and toxic metabolites such as glycolic and oxalic acids (Egbert 

and Abraham 1999). Sodium bicarbonate infusion is used to correct metabolic acidosis, increase 

elimination of renal glycolic acid, and inhibit the precipitation of calcium oxalate crystals, although the 

latter benefit has not been demonstrated in clinical trials (Egbert and Abraham 1999; Leth and Gregersen 

2005; Scalley et al. 2002). 

Hemodialysis is indicated when initial serum ethylene glycol levels exceed 50 mg/dL or when ingestion 

of ethylene glycol results in refractory acidosis, deteriorating clinical status, or renal compromise (Egbert 

and Abraham 1999; Mégarbane et al. 2005; Scalley et al. 2002). Hemodialysis can effectively remove 

ethylene glycol and the acid metabolites, glycolic and oxalic acids, because they have low molecular 

weights and do not exhibit protein binding (Egbert and Abraham 1999). Hemodialysis is also effective in 

treating metabolic acidosis (Leth and Gregersen 2005; Scalley et al. 2002). 

Thiamine (vitamin B1) and pyroxidine (vitamin B6) are co-factors for the metabolism of ethylene glycol. 

Thiamine is believed to reduce the formation of toxic oxalic acid by shifting glyoxylic acid metabolism to 

the less toxic α-hydroxy-β-ketoadipic acid (Egbert and Abraham 1999; Goldfrank et al. 2002). 

Pyroxidine, in the presence of magnesium, may promote the conversion of glyoxylic acid to glycine and 

benzoic acid, which also results in reduced toxic oxalic acid formation (Egbert and Abraham 1999; 

Gardner et al. 2004; Goldfrank et al. 2002; Leth and Gregersen 2005; Scalley et al. 2002). However, the 

efficacy of treatment with thiamine and pyroxidine has not been demonstrated in human cases of ethylene 

glycol poisoning. 

Some recent investigations have focused on methods to prevent or reduce calcium oxalate formation. 

Calcium oxalate, an end metabolite of ethylene glycol and a major component of kidney stones, has been 

demonstrated to cause cytotoxicity in cultured human proximal tubule cells (Guo and McMartin 2005; 

Guo et al. 2007). Treatment with aluminum citrate was shown to significantly decrease calcium oxalate-
 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 156 

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induced cytotoxicity (Guo and McMartin 2007). These results indicate that aluminum citrate may protect 

against tissue damage caused by high levels of calcium oxalate accumulation. In rats administered 

ethylene glycol in the drinking water at sufficient concentrations to induce the precipitation of calcium 

oxalate in proximal renal tubules, intraperitoneal injection of thymoquinone (a major component of 

Nigella sativa seeds) significantly decreased the number and size of the calcium oxalate deposits 

(Hadjzadeh et al. 2008). However, the usefulness of thymoquinone as a therapeutic drug for kidney 

calculi requires further investigation. 

3.11.3 Interfering with the Mechanism of Action for Toxic Effects 

There are no documented methods for interfering with mechanisms of action for toxic effects of ethylene 

glycol and its potent metabolites. As described in Section 3.11.2, clinical procedures for treating ethylene 

glycol poisoning consist of measures focused on reduction of the body burden of parent compound and its 

metabolites that are responsible for ethylene glycol-induced adverse neurological, cardiovascular, 

metabolic, and renal effects. 

3.12 ADEQUACY OF THE DATABASE 

Section 104(I)(5) of CERCLA, as amended, directs the Administrator of ATSDR (in consultation with the 

Administrator of EPA and agencies and programs of the Public Health Service) to assess whether 

adequate information on the health effects of ethylene glycol is available. Where adequate information is 

not available, ATSDR, in conjunction with the National Toxicology Program (NTP), is required to assure 

the initiation of a program of research designed to determine the health effects (and techniques for 

developing methods to determine such health effects) of ethylene glycol. 

The following categories of possible data needs have been identified by a joint team of scientists from 

ATSDR, NTP, and EPA. They are defined as substance-specific informational needs that if met would 

reduce the uncertainties of human health assessment. This definition should not be interpreted to mean 

that all data needs discussed in this section must be filled. In the future, the identified data needs will be 

evaluated and prioritized, and a substance-specific research agenda will be proposed. 

3.12.1 Existing Information on Health Effects of ethylene glycol 

The existing data on health effects of inhalation, oral, and dermal exposure of humans and animals to 

ethylene glycol are summarized in Figure 3-5. The purpose of this figure is to illustrate the existing 
 

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ETHYLENE GLYCOL 157 

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Figure 3-5. Existing Information on Health Effects of Ethylene Glycol 
 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 158 

3. HEALTH EFFECTS 

information concerning the health effects of ethylene glycol. Each dot in the figure indicates that one or 

more studies provide information associated with that particular effect. The dot does not necessarily 

imply anything about the quality of the study or studies, nor should missing information in this figure be 

interpreted as a “data need”. A data need, as defined in ATSDR’s Decision Guide for Identifying 

Substance-Specific Data Needs Related to Toxicological Profiles (Agency for Toxic Substances and 

Disease Registry 1989), is substance-specific information necessary to conduct comprehensive public 

health assessments. Generally, ATSDR defines a data gap more broadly as any substance-specific 

information missing from the scientific literature. 

Information on the health effects of ethylene glycol inhalation in humans is limited to an experimental 

study of acute- to intermediate-duration exposure providing data on respiratory, renal, neurologic, and 

other systemic end points, an intermediate-duration study of kidney function in workers, and a chronic 

renal cancer mortality study in workers. Inhalation data in animals are also limited, consisting of three 

acute-duration developmental toxicity studies in rats and mice and an intermediate-duration systemic 

toxicity studies in rats, guinea pigs, rabbits, dogs, and monkeys. 

Health effects data in orally exposed humans comprise numerous case reports of acute ingestion 

documenting the progression of neurologic, cardiovascular, renal, and other systemic effects. The health 

effects of ethylene glycol in orally exposed animals are generally well documented in acute-, 

intermediate-, and chronic-duration studies of systemic, reproductive, and developmental toxicity and 

carcinogenicity in rats and mice. A limited amount of information is available on the immunologic, 

lymphoreticular, and neurological effects of oral exposure in animals. 

Information on the health effects of dermal exposure to ethylene glycol is essentially limited to two acuteduration studies in animals investigating skin and eye irritation in rabbits and developmental toxicity in 

mice. 

3.12.2 Identification of Data Needs 

Acute-Duration Exposure. Information on the toxicity of acute-duration inhalation exposure to 

ethylene glycol is available from an experimental study in humans (Wills et al. 1974) and three 

developmental toxicity studies in rats and mice (Tyl 1988a; Tyl et al. 1995a, 1995b). In the human study, 

exposure to ethylene glycol aerosol at an average concentration of 23 mg/m3 for 20–22 hours/day for 

14 days was well-tolerated in 19 subjects with effects that were essentially limited to occasional 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 159 

3. HEALTH EFFECTS 

complaints of mild upper respiratory tract irritation; there were no indications of renal or other systemic 

effects as shown by urinalysis and hematology, clinical chemistry, and neurobehavioral evaluations (Wills 

et al. 1974). Short-term (e.g., 15-minute), high-exposure sessions showed that ethylene glycol was 

tolerated for only 15 minutes at 188 mg/m3

, 2 minutes at 244 mg/m3, and one or two breaths at 

308 mg/m3

. The study authors stated that irritation became common at approximately 140 mg/m3 

(incidences and exposure duration not specified) and concluded that concentrations ≥200mg/m3 were 

intolerable due to strong irritation of the upper respiratory tract that included a burning sensation in the 

trachea and a burning cough. The developmental studies (Tyl 1988a; Tyl et al. 1995a, 1995b) are limited 

by confounding oral exposures, as discussed in data needs for Developmental Toxicity, but collectively 

suggest that 150 mg/m3 is a conservative NOAEL for developmental toxicity in rats and kidney toxicity in 

mice. This concentration is similar to the 140 mg/m3 LOAEL for respiratory tract irritation in humans 

(Wills et al. 1974). The human NOAEL of 23 mg/m3 is a suitable basis for acute inhalation MRL 

derivation because it is based on evaluations for renal and other systemic effects as well as local irritation, 

and is within the NOAEL range for developmental toxicity in animals. Additional studies would help to 

define the threshold for respiratory irritation in humans, particularly for acute exposures longer than 

several minutes, and confirm that the respiratory tract is the most sensitive target for acute exposure. 

These inhalation studies could also address the potential increased toxicity of ethylene glycol when it is 

heated (e.g., through its use as an automobile antifreeze/coolant). 

Information on effects of acute-duration oral exposure to ethylene glycol is available from human case 

reports (Godolphin et al. 1980; Gordon and Hunter 1982; Hewlett et al. 1986; Jacobsen et al. 1984; Siew 

et al. 1975a; Zeiss et al. 1989), a 10-day drinking water study in rats (Robinson et al. 1990), a 4-day 

gavage study examining effects on hematology and reproductive organs (Hong et al. 1988), and 

developmental toxicity studies in mice, rats, and rabbits (Maronpot et al. 1983; Marr et al. 1992; NeeperBradley et al. 1995; Price et al. 1985; Schuler et al. 1984; Tyl 1989; Tyl et al. 1993). The available 

human studies consist of clinical case reports of high-dose intentional or accidental ingestion of ethylene 

glycol, and thus, are not suitable for dose-response assessment or MRL consideration. The 4-day gavage 

study (Hong et al. 1988) identified bone marrow effects in mice at doses of 50–250 mg/kg/day; these 

included suppressed granulocyte-macrophage progenitor formation at ≥50 mg/kg/day, bone marrow 

hypocellularity at ≥100 mg/kg/day, and suppressed iron uptake in the bone marrow at 250 mg/kg/day. 

The biological significance of these effects is uncertain in light of the lack of supporting evidence for 

effects on bone marrow, spleen, or hematology in longer-duration studies of mice and rats exposed to 

much higher doses (DePass et al. 1986a; Gaunt et al. 1974; Melnick 1984; NTP 1993; Robinson et al. 

1990; Schladt et al. 1998). Additional testing for acute bone marrow effects is needed to corroborate the 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 160 

3. HEALTH EFFECTS 

findings of the Hong et al. (1988) study, clarify their biological significance, and confirm that bone 

marrow effects are not an appropriate basis for MRL derivation. The remaining animal studies 

collectively identify the developing fetus as the most sensitive target of acute oral exposure to ethylene 

glycol. Among the developmental toxicity studies, the study by Neeper-Bradley et al. (1995; Tyl 1989) in 

mice identified the lowest LOAEL (500 mg/kg/day for increased incidence of total malformations and 

bilateral extra rib 14), and dose-response data for these effects were used in deriving the acute oral MRL 

for ethylene glycol. 

Information on the acute dermal toxicity of ethylene glycol is limited to one study in rabbits that found 

minimal skin and eye irritation following single applications (Clark et al. 1979) and one negative 

developmental toxicity study in mice exposed to 3,549 mg/kg/day for 6 hours/day on Gd 6–15 (Tyl 

1988b; Tyl et al. 1995c). Additional dermal studies would be helpful in evaluating the potential for 

systemic toxicity by this route of exposure. 

Intermediate-Duration Exposure. Information on the toxicity of intermediate-duration inhalation 

exposure to ethylene glycol is available from two studies in humans (Gérin et al. 1997; Wills et al. 1974) 

and one multiple species study in animals (Coon et al. 1970). In one of the human studies, health effects 

were assessed in 19 subjects who were exposed to ethylene glycol aerosol at an average concentration of 

30 mg/m3 for 20–22 hours/day for 30 days (Wills et al. 1974). The near-continuous exposure was 

tolerated with effects that included occasional complaints of upper respiratory tract irritation, slight 

headache, and low backache. These occasional complaints were not associated with any particular 

exposure concentration and incidence and frequency data were not included in the study report; there was 

no mention of self-reported results from a control group. Therefore, neither a reliable LOAEL nor a 

definitive NOAEL were established in this study. The study found no indications of renal or other 

systemic effects as shown by urinalysis and hematology, clinical chemistry, and neurobehavioral 

evaluations. The other human study found no effects on kidney function in 33 male aviation workers who 

were intermittently exposed to ethylene glycol during airplane de-icing operations during a 2-month 

winter period (Gérin et al. 1997), but identification of a NOAEL is precluded by inadequate monitoring 

data. In the animal study, rats, guinea pigs, and small numbers of rabbits, dogs, and monkeys were 

exposed to ethylene glycol aerosol in concentrations of 0, 10, or 57 mg/m3 for 8 hours/day, 5 days/week 

for 6 weeks, or to 0 or 12 mg/m3 continuously for 90 days (Coon et al. 1970). The 6-week intermittent 

exposure study identified a NOAEL of 57 mg/m3 for kidney histopathology and other systemic effects in 

all species. Continuous exposure to 12 mg/m3 for 90 days caused ocular irritation and/or mortality in rats, 

rabbits, and guinea pigs (Coon et al. 1970), but confidence in this LOAEL is low due to small numbers of 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 161 

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animals and likely confounding by oral exposure from ingestion of aerosol deposited on the fur, and its 

relevance is unclear because there were no eye irritation or other effects in humans near-continuously 

exposed to 30 mg/m3 for 30 days (Wills et al. 1974). Although exposures as long as 90 days were 

conducted in the animal study, it was limited in scope (e.g., lacked sufficient numbers of animals and 

urinalysis) and likely confounded by oral exposure. A well-designed, intermediate-duration systemic 

toxicity study in animals is needed to provide a sufficient basis for inhalation MRL derivation. 

Information on intermediate-duration oral toxicity of ethylene glycol essentially consists of several 

generally well-designed studies in rats (Cruzan et al. 2004; Gaunt et al. 1974; Melnick 1984; Robinson et 

al. 1990) and mice (Melnick 1984; NTP 1993). These studies consistently showed that the kidney is the 

predominant and most sensitive target of intermediate-duration oral exposure, and that renal toxicity 

varied with sex, species, and strain, with males more sensitive than females, rats more sensitive than 

mice, and Wistar rats more sensitive than other strains of rats. The 16-week studies of Cruzan et al. 

(2004) and Gaunt et al. (1974) were considered for intermediate oral MRL consideration because they 

provide dose-response data for the critical effect in the most sensitive species, strain, and sex (i.e., kidney 

lesions in male Wistar rats). The NOAEL and LOAEL values were 150 and 500 mg/kg/day in the Cruzan 

et al. (2004) study and 71 and 180 mg/kg/day in the Gaunt et al. (1974) study. Although Gaunt et al. 

(1974) identified a lower apparent LOAEL, this study is not suitable for MRL consideration because the 

animal care was questionable and the daily dose was not constant. Nearly all of the rats showed evidence 

of respiratory infection (pneumonia) and infectious salivary adenitis, either of which could have 

confounded the results. Chemical intake varied throughout the study because the amount of ethylene 

glycol in the diet was not adjusted for changing food consumption and body weight. The Cruzan et al. 

(2004) study is considered adequate for deriving an intermediate-duration oral MRL for ethylene glycol 

because it does not have the limitations of the Gaunt et al. (1974) study. The data set for the critical effect 

(crystal nephropathy) is not appropriate for BMD analysis because the incidences increased from 0% at 

doses ≤150 mg/kg/day to 100% at the higher dose levels (i.e., 500 and 1,000 mg/kg/day). Basing the

intermediate-duration MRL on the NOAEL of 150 mg/kg/day yields a value that is higher than the acuteduration oral MRL. Because available evidence indicates that the acute-duration oral MRL for ethylene 

should be protective for kidney effects following longer-term exposure, the acute-duration value was 

adopted for intermediate-duration exposure. An intermediate-duration oral toxicity study in male Wistar 

rats that provides dose-response data for kidney effects in the 150–300 mg/kg/day dose range is needed to 

provide a suitable basis for MRL derivation. 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 162 

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No information is available on the intermediate-duration dermal toxicity of ethylene glycol. Studies using 

the dermal route would be useful because absorption and systemic distribution of ethylene glycol has 

been shown in dermal toxicokinetic studies in rats and mice (Frantz et al. 1989, 1991, 1996b, 1996c). 

Chronic-Duration Exposure and Cancer. Information on the health effects of chronic inhalation 

exposure to ethylene glycol is essentially limited to the negative results of an epidemiologic study on 

renal cancer mortality in humans (Bond et al. 1985). This study is not suitable for assessing chronic 

inhalation toxicity because it lacks noncancer end points, measured exposure concentrations, and other 

relevant information. Chronic testing in animals is needed to provide a basis for chronic inhalation MRL 

derivation and to adequately assess the potential for inhalation carcinogenicity. 

Chronic oral effects of ethylene glycol have been evaluated in three studies in rats (Blood 1965; Corley et 

al. 2008; DePass et al. 1986a) and two studies in mice (DePass et al. 1986a; NTP 1993) using dietary 

exposure. None of the studies provided evidence of carcinogenicity. The main target organs for toxicity 

were the kidneys in rats and liver in mice, and rats were more sensitive than mice. Effects in the rats 

included kidney lesions and mortality at doses ≥300 mg/kg/day in Wistar males (Corley et al. 2008), 

kidney lesions at doses ≥375 mg/kg/day and mortality at 750 mg/kg/day in Sprague-Dawley males (Blood 

1965), and kidney lesions and mortality at 1,000 mg/kg/day in F344 males (DePass et al. 1986a). The 

study in male Wistar rats (Corley et al. 2008) is the most appropriate basis for chronic MRL derivation 

because it identified the lowest LOAEL (300 mg/kg/day) and is the only study providing information on 

effects of chronic exposure in Wistar rats, a strain shown to be approximately twice as sensitive as F344 

rats to kidney toxicity in a 16-week study (Cruzan et al. 2004). The data set for the critical effect in this 

study, oxalate nephropathy is not appropriate for BMD analysis because the incidences increased from 

0% in the rats at doses ≤150 mg/kg/day to 92% at 300 mg/kg/day (next highest dose) and 100% at

400 mg/kg/day (highest dose). Basing the MRL on the NOAEL of 150 mg/kg/day yields an intermediateduration MRL that is higher than the acute-duration oral MRL. It is against ATSDR policy to derive a 

chronic-duration MRL that is higher than the acute-duration MRL, although available evidence indicates 

that the acute MRL should be protective for chronic kidney effects. A chronic oral study in male Wistar 

rats that provides dose-response data for kidney effects in the 150–300 mg/kg/day dose range is needed to 

increase confidence in the chronic-duration oral MRL. This study could also be used to confirm the lack 

of carcinogenicity in the available studies. 

Genotoxicity. Human genotoxicity data were not located for ethylene glycol. A single in vivo study 

was located in which ethylene glycol did not produce dominant lethality in orally-exposed rats (DePass et 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 163 

3. HEALTH EFFECTS 

al. 1986b). Available in vitro assays in a variety of test systems consistently provide negative results for 

genotoxicity (Abbondandolo et al. 1980; Clark et al. 1979; Griffiths 1979, 1981; Hastwell et al. 2006; 

Kubo et al. 2002; McCann et al. 1975; McCarroll et al. 1981; McGregor et al. 1991; Miller et al. 2005; 

Pfeiffer and Dunkelberg 1980; Storer et al. 1996; Zeiger et al. 1987). Additional in vivo animal studies 

could be conducted to more completely assess the genotoxicity of ethylene glycol, although available data 

do not indicate that the compound is of genotoxicity concern. 

Reproductive Toxicity. Studies have not addressed the reproductive toxicity of ethylene glycol in 

humans. Reproductive testing in animals includes three multigeneration studies (one in rats and two in 

mice) and several shorter studies (15–20 days in rats and mice) by the oral route (DePass et al. 1986b; 

Harris et al. 1992; Lamb et al. 1985; Morrissey et al. 1989; NTP 1986. 1988). The only effect in rats was 

an increase in gestational duration, whereas fertility and fetal viability were affected in mice. Mice also 

showed some changes in sperm parameters, as well as testicular and epididymal lesions (Morrissey et al. 

1989; NTP 1986); however, the incidence of testicular effects was high in the control group, so the 

relationship to ethylene glycol exposure is uncertain. Additional reproductive testing may not be needed 

because several multigeneration studies have been conducted, most studies suggest that reproductive 

effects occur at higher doses than developmental effects, and there are no toxicokinetic data suggesting 

that reproductive effects would be route-specific. 

Developmental Toxicity. Studies have not addressed the developmental toxicity of ethylene glycol 

in humans. The developmental toxicity of oral exposure to ethylene glycol has been studied in rats, mice 

and rabbits over a wide range of doses (DePass et al. 1986b; Harris et al. 1992; Lamb et al. 1985; 

Maronpot et al. 1983; Marr et al. 1992; Morrissey et al. 1989; Neeper-Bradley 1990; Neeper-Bradley et 

al. 1995; NTP 1986; Price et al. 1985; Schuler et al. 1984; Tyl 1989; Tyl et al. 1993), indicating that 

further evaluation of the developmental toxicity of orally-administered ethylene glycol toxicity may not 

be warranted. The most sensitive indicator of developmental toxicity appears to be an increased 

incidence of malformations, primarily skeletal malformations, in both mice and rats. Available data 

suggest that malformations appear in mice at lower doses than those which cause malformations in rats. 

As indicated in the discussion of data needs for Acute-Duration Exposure, the acute oral MRL for 

ethylene glycol is based on developmental effects in mice exposed to ethylene glycol daily by gavage on 

Gd 6–15 (Neeper-Bradley et al. 1995; Tyl 1989). An uncertainty in the acute-duration oral MRL that 

may need to be addressed stems from the use of gavage administration in the MRL study. Bolus doses 

from gavage administration lead to higher peak blood concentrations of glycolic acid (the proximate 

developmental toxicant) than occur with slower dose-rates associated with environmentally-relevant 
 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 164 

3. HEALTH EFFECTS 

exposures (Carney et al. 2001; Corley et al. 2002; NTP-CERHR 2004). Because the MRL study used 

gavage administration, the dose at which effects were observed is likely lower than would be observed 

with non-bolus dosing. 

Developmental toxicity has also been assessed in rats and mice by the inhalation route. Results of the 

inhalation developmental studies are generally consistent with the oral findings, but are confounded by 

concurrent oral exposure via ingestion of aerosolized ethylene glycol on the fur of exposed animals (Tyl 

1985, 1988a; Tyl et al. 1995a, 1995b). The studies included a nose-only inhalation study in mice aimed 

at reducing the confounding oral exposure, but these animals had exposure by ingestion of ethylene glycol 

deposited on the face (Tyl 1988a; Tyl et al. 1995a). Additionally, stress from restraint in the nose-only 

exposure study may have contributed to the developmental effects observed with ethylene glycol 

(NTP-CERHR 2004), which were similar in nature to effects observed in a study of restrained nose-only 

exposure to water vapor (Tyl et al. 1994). Because of the confounding oral exposure in both the wholebody and nose-only studies, as well as the confounding effect of stress due to restraint in the nose-only 

study, additional testing is needed to adequately evaluate developmental effect levels from inhalation 

exposure to ethylene glycol. Given the problems of oral exposure from deposition of ethylene glycol on 

the fur, the feasibility of conducting an adequate inhalation study is unclear. 

A single well-designed study of dermal gestational exposure to ethylene glycol found no developmental 

toxicity in mice (Tyl 1988b; Tyl et al. 1995c). Additional dermal testing could confirm the apparent low 

potential for developmental toxicity by this route of exposure. 

Immunological and Lymphoreticular Effects. A limited amount of information on 

immunological and lymphoreticular effects of ethylene glycol is available from oral studies in animals. 

There were no histopathological alterations in the spleen, lymph nodes, or thymus, or consistent changes 

in leukocyte counts in rats or mice in acute-, intermediate-, and chronic-duration oral studies of ethylene 

glycol (Blood 1965; DePass et al. 1986a; Gaunt et al. 1974; Hong et al. 1988; Melnick 1984; NTP 1993; 

Robinson et al. 1990; Schladt et al. 1998). Immune responses were suppressed in mice administered a 

single 12,000 mg/kg (0.8 LD50) gavage dose of ethylene glycol; effects included increased mortality from 

E. coli-induced infection, decreased number of spleen colony-forming units, decreased numbers of 

antibody-producing cells in spleen to sheep erythrocytes and Vi-agglutinin, decreased activity of natural 

killer cells, decreased antibody-dependent cytotoxicity of splenocytes to sheep erythrocytes, and 

decreased delayed-type hypersensitivity to sheep erythrocytes (Zabrodskii and Germanchuk 2000; 

Zabrodskii et al. 2003). Other dose levels were not tested in this study. Although the findings indicate 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 165 

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that a very high single dose of ethylene glycol was immunotoxic in mice, no studies of immune function 

following repeated acute exposure (e.g., 14 days) or intermediate- or chronic-duration exposure have been 

conducted. Comprehensive immunological testing that includes a range of dose levels and repeated 

exposures is needed to adequately assess the immunotoxic potential of ethylene glycol. 

Neurological Effects. Information on the neurotoxicity of inhaled ethylene glycol is essentially 

limited to a human study in which subjects were exposed to ethylene glycol aerosol for 20–22 hours/day 

for up to 30 days (Wills et al. 1974). No effects were seen in electroencephalographs or a battery of 

psychological tests conducted after 14 and 30 days of exposure (23 and 30 mg/m3

, respectively); the tests 

evaluated simple reaction time, reaction time with discrimination, visual-motor coordination, depth 

perception, and mental ability (encoding and subtraction accuracy). There were no clear clinical signs of 

neurotoxicity; slight headache and backache were occasional complaints, but incidence and frequency 

were not reported. No human or animal studies were located that provide information on neurological 

effects of dermal exposure. 

The neurotoxicity of acute oral exposure to large doses of ethylene glycol is well characterized in 

humans. Adverse neurological reactions are among the first symptoms to appear in human ethylene 

glycol poisoning. These symptoms are attributable directly to unmetabolized ethylene glycol, resemble 

ethanol intoxication, occur within 30 minutes to 12 hours after exposure, and include ataxia, 

disorientation, restlessness, slurred speech, and somnolence, progressing to convulsions and coma (Cheng 

et al. 1987; Factor and Lava 1987; Gordon and Hunter 1982; Robinson and McCoy 1989; Vale 1979; 

Woolf et al. 1992). Some evidence exists that damage to the cranial nerves may occur much later in the 

toxic process, especially if supportive therapy is delayed (Chung and Tuso 1989; Factor and Lava 1987; 

Lewis et al. 1997; Mallya et al. 1986; Spillane et al. 1991). 

Clinical signs of neurotoxicity similar to those in humans summarized above occurred in rats, dogs, and 

cats following administration of large oral bolus doses of ethylene glycol (Beckett and Shields 1971; 

Clark et al. 1979; Dial et al. 1994; Grauer et al. 1987; Penumarthy and Oehme 1975). No clinical signs of 

neurotoxicity or histopathological changes in brain, spinal cord, or peripheral nerve tissue were observed 

in rats or mice exposed to ethylene glycol in the diet or drinking water in acute-, intermediate-, or 

chronic-duration studies (Blood 1965; DePass et al. 1986a; Gaunt et al. 1974; Melnick 1984; NTP 1993; 

Robinson et al. 1990; Schladt et al. 1998). Tests of neurobehavioral function have not been conducted in 

orally-exposed animals. Although there were no effects on neurobehavioral function in humans exposed 
 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 166 

3. HEALTH EFFECTS 

by inhalation (Wills et al. 1974), neurobehavioral testing in orally-exposed animals is needed to 

adequately assess the neurotoxic potential of lower doses of ethylene glycol. 

Epidemiological and Human Dosimetry Studies. A limited amount of epidemiological data on 

ethylene glycol is available from two studies of workers mainly exposed by inhalation with possible 

secondary exposure by the dermal route. One of these occupational studies evaluated kidney function in a 

small number of aviation workers who were intermittently exposed to ethylene glycol during airplane deicing operations over a 2-month winter period (Gérin et al. 1997). Personal exposures to ethylene glycol 

vapor and aerosol were measured, but most samples were below the detection limit and average levels 

were not reported. This study found no indication of renal impairment based on a limited number of 

urinary end points (albumin, β-N-acetyl-glucosaminidase, β-2-microglobulin, and retinol-binding 

protein). The other study assessed renal cancer mortality in 1,666 chemical plant employees and found no 

increase in a small number of workers exposed to unmeasured levels of ethylene glycol (Bond et al. 

1985). Epidemiological studies of orally-exposed humans are not available, although numerous clinical 

case reports of intentional or accidental ingestion have documented neurological, renal, and other effects 

of high acute doses of ethylene glycol. The available information suggests that ethylene glycol is likely to 

cause effects in humans similar to those found in animals. Additional epidemiological studies 

investigating dose-response relationships between ethylene glycol exposure and likely target organ 

toxicity would be useful. Potential study populations include individuals exposed through dermal contact 

with ethylene glycol-containing automobile antifreeze and individuals who live near hazardous waste 

sites, industrial facilities where ethylene glycol is produced or used, or areas where ethylene glycol-based 

de-icing formulations are used and may be exposed through dermal contact with contaminated soil or 

water, inhalation of ethylene glycol vapor or mist, or ingestion of contaminated groundwater. 

Additionally, occupational exposure through inhalation of ethylene glycol vapor or mist and dermal 

contact is expected for individuals involved in airport de-icing spray operations. Background exposure of 

the general population is not expected to be important because ethylene glycol is rapidly degraded in air, 

water, and soil, and available monitoring data indicate that it is only found near areas of release (Atkinson 

1989; Battersby and Wilson 1989; Conway et al. 1983; Kameya et al. 1995; McGahey and Bouwer 1992; 

Revitt and Worrall 2003; Schoenberg et al. 2001; Staples et al. 2001). 

Biomarkers of Exposure and Effect. 

Exposure. The only biomarker of exposure that is specific to ethylene glycol is parent compound in the 

blood and urine. Based on the relatively short half-life of ethylene glycol in the blood and urine (Eder et 
 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 167 

3. HEALTH EFFECTS 

al. 1998; Jacobsen et al. 1988; Peterson et al. 1981), parent compound would likely be detectable only 

within a few hours to 1 day following acute ingestion. Rapid methods for determining ethylene glycol in 

serum and urine are available for use in the clinical setting (Aarstad et al. 1993; Blandford and Desjardins 

1994), but are often not readily available in emergency situations. 

Other identified biomarkers of exposure are not specific to ethylene glycol. They include ethylene glycol 

metabolites such as glycolic, lactic, and oxalic acids in blood and/or urine; and calcium oxalate 

monohydrate crystals in renal tubules and/or urine. However, increased blood glycolate above normal 

human background levels is strongly indicative of ethylene glycol exposure and is often used for clinical 

diagnosis or confirmation. 

Based on available information regarding the toxicokinetics of ethylene glycol and its metabolites, and 

available methods for identifying parent compound and metabolites in body fluids, it appears that 

ethylene glycol poisoning can be adequately diagnosed in most cases. Additional studies to assess 

additional potential biomarkers of exposure for ethylene glycol do not appear necessary at this time. 

Effect. Biomarkers of effects exist for ethylene glycol poisoning, but none are specific to ethylene glycol. 

These include clinical manifestations of central nervous system, cardiopulmonary, and renal toxicity, and 

laboratory findings of metabolic acidosis and calcium oxalate crystalluria. Clinical manifestations 

progress in three main stages. Signs of central nervous system toxicity appear within 0.5–12 hours 

following acute ingestion, although manifestations suggestive of cranial nerve damage may appear as late 

as 1–2 weeks after exposure (CDC 1987; Cheng et al. 1987; Chung and Tuso 1989; Factor and Lava 

1987; Hess et al. 2004; Leth and Gregersen 2005; Lewis et al. 1997; Mallya et al. 1986; Parry and 

Wallach 1974; Rothman et al. 1986; Spillane et al. 1991; Underwood and Bennett 1973; Zeiss et al. 

1989). Cardiopulmonary manifestations generally develop after 12–24 hours and renal failure occurs 

after 24–72 hours (Godolphin et al. 1980; Hess et al. 2004; Leth and Gregersen 2005; Parry and Wallach 

1974; Siew et al. 1975a; Vale 1979; Zeiss et al. 1989). Ethylene glycol-induced metabolic acidosis 

occurs approximately 12–24 hours following ingestion and is characterized by pronounced serum osmolal 

and anion gaps (Eder et al. 1998; Hess et al. 2004; Hoffman et al. 1993; Gabow et al. 1986; Jacobsen et 

al. 1984; Leth and Gregersen 2005). Calcium oxalate crystals in the urine can appear 4–8 hours after 

ethylene glycol ingestion, and deposition of crystals in the renal tubules can subsequently result in 

nephropathy and eventual renal failure 24–72 hours after ingestion (CDC 1987; Chung and Tuso 1989; 

Factor and Lava 1987; Godolphin et al. 1980; Heckerling 1987; Jacobsen et al. 1988; Leth and Gregersen 

2005; Parry and Wallach 1974; Rothman et al. 1986; Siew et al. 1975a; Underwood and Bennett 1973). 
 

 

 

 

 

 

 

ETHYLENE GLYCOL 168 

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Based on the well-characterized sequence of events and toxicity targets of ethylene glycol poisoning, 

studies for additional biomarkers of effect for ethylene glycol do not appear necessary. 

Absorption, Distribution, Metabolism, and Excretion. Additional data are needed to quantify 

the absorption, distribution, metabolism, and excretion of inhaled ethylene glycol across relevant 

concentration ranges in humans and animals. Only two studies evaluating toxicokinetic data in humans 

exposed via inhalation was identified (Carstens et al. 2003; Upadhyay et al. 2008). However, these 

studies are limited by inadequate definition of exposure levels and a lack of data on expired CO2. 

Similarly, one study of the toxicokinetics of inhaled ethylene glycol in animals used only a single vapor 

and a single aerosol concentration (Marshall and Cheng 1983). 

Although the human oral absorption of ethylene glycol has not been quantitatively characterized, case 

reports indicate that humans can absorb toxicologically significant amounts of this compound by the oral 

route (Godolphin et al. 1980; Gordon and Hunter 1982; Hewlett et al. 1986; Jacobsen et al. 1984, 1988; 

Karlson-Stiber and Persson 1992; Litovitz et al. 1990, 1991; Peterson et al. 1981; Siew et al. 1975a; 

Walton 1978; Zeiss et al. 1989). In addition, several case reports (Cheng et al. 1987; Hewlett et al. 1986; 

Jacobsen et al. 1984, 1988; Peterson et al. 1981; Rothman et al. 1986) provide data on plasma levels of 

ethylene glycol or glycolate in humans acutely poisoned with ethylene glycol. While the tissue levels of 

ethylene glycol in humans exposed orally have not been studied, information on the volume of 

distribution and urine-to-plasma concentration ratios suggest distribution with total body water (Jacobsen 

et al. 1988). Data on the distribution of radioactivity in mice, rats, and monkeys exposed orally support 

this finding (Frantz et al. 1989, 1991, 1996b, 1996c; McChesney et al. 1971). 

The in vivo metabolism of ethylene glycol has been thoroughly studied in rats and mice exposed via 

intravenous, oral, and dermal routes (Frantz et al. 1989, 1991, 1996b, 1996c). Data on plasma and urinary 

metabolites from these studies support the widely accepted metabolic scheme for ethylene glycol. 

Because metabolites of ethylene glycol (glycolic and oxalic acids) have been identified as the probable 

proximate toxicants (for both renal and developmental effects), additional data on the specific isozymes 

responsible for metabolizing ethylene glycol and glycolic acid, inter-individual variability in metabolic 

parameters (e.g., polymorphisms in genes encoding these isozymes), and developmental ontogeny of 

these isozymes are needed to better characterize species differences and identify sensitive subpopulations. 

In addition, further information is needed on species differences in metabolic rates and saturation points, 

as available data provide inadequate information on the relative sensitivity of humans and laboratory 

rodents. 
 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 169 

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Because most human exposure has been associated with acute accidental or intentional poisoning 

incidents, there are few data on the elimination kinetics of ethylene glycol after oral exposure in humans. 

Most of the available estimates of plasma elimination half-lives have been confounded by concurrent 

therapeutic treatments such as ethanol administration or hemodialysis that modify elimination kinetics. 

Elimination of orally-administered ethylene glycol across a broad dose range has been thoroughly studied 

in rats and mice (Frantz et al. 1989, 1991, 1996b, 1996c), and to a more limited extent in monkeys 

(McChesney et al. 1971). 

Information regarding the dermal absorption of ethylene glycol in humans is limited. Results of 

Upadhyay et al. (2008) indicate that only approximately 1% of an epidermally applied dose may be 

absorbed. No data were found regarding the kinetics of dermally absorbed ethylene glycol in humans. 

The in vitro permeability of human skin to ethylene glycol has been studied, with widely varying results. 

Using full-thickness cadaver skin, Loden (1986) estimated a percutaneous absorption rate of 

118 μg/cm2

/hour with a steady-state concentration of 0.97 mg/cm2, while Driver et al. (1993) estimated 

absorption rates of 0.09–0.25 μg/cm2

/hour for three different skin samples. Although the absorption, 

distribution, metabolism, and elimination of ethylene glycol administered dermally has been thoroughly 

studied in rats and mice (Frantz et al. 1989, 1991, 1996b, 1996c), acute in vivo studies in humans are 

needed to better characterize the toxicokinetics for this route of exposure. 

All of the toxicokinetic data in humans and animals were collected after acute exposures to ethylene 

glycol; there are no data on toxicokinetics after intermediate- or chronic-duration exposures. 

Intermediate- and chronic-duration data are needed in order to adequately assess absorption, metabolism, 

and elimination with prolonged exposure. Studies with heated ethylene glycol would be useful due to the 

potential increased toxicity of ethylene glycol when it is heated (e.g., through its use as an automobile 

antifreeze/coolant). 

Comparative Toxicokinetics. Species differences in in vivo toxicokinetics are not well 

characterized. While there are high quality toxicokinetic data comparing absorption, distribution, 

metabolism, and excretion in mice and rats (Frantz et al. 1989, 1991, 1996a, 1996b, 1996c), available data 

in other species (Hewlett et al. 1989; McChesney et al. 1971) are more limited; in many cases, only single 

dose levels were used, the numbers of animals per dose were small, and mass balance information was 

incomplete. Available data in humans are limited to acute, high-dose exposures, with toxicokinetic data 

often confounded by the effects of therapeutic interventions. 
 

 

 

 

 

 

 

 

 

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Using a PBPK model for humans, Corley et al. (2005) estimated that the threshold glycolic acid 

concentration for developmental effects in rodents (considered by the authors to be a peak of 2 mM) 

would only be reached in human females ingesting doses of 350 mg/kg (assuming a 58-kg female). 

However, the model was not calibrated to pregnancy, and it is not clear whether physiological and/or 

biochemical changes that could affect ethylene glycol toxicokinetics might occur during pregnancy. 

Slikker et al. (2004) reported that there are species-specific differences in the transfer of glycolic acid, the 

primary metabolite and putative developmental toxicant associated with ethylene glycol exposure, from 

maternal blood to conceptus. NTP-CERHR (2004) noted that the inverted yolk sac placenta that develops 

in both mice and rats tends to concentrate weak acids including glycolic acid; neither humans nor rabbits 

develop a yolk sac placenta. A preliminary study by Carney and coworkers (2001) showed that glycolic 

acid does not concentrate in rabbit embryonic fluids, while Corley et al. (2002) have shown in rats that 

glycolic acid is consistently higher in the conceptus compared to the maternal blood. In addition, fetal 

and/or placental differences in expression of enzymes metabolizing ethylene glycol and glycolic acid over 

the course of gestation will affect local concentrations of glycolic acid to which the developing conceptus 

is exposed, yet little is known about species differences in the ontogeny of these enzymes (NTP-CERHR 

2004). 

Additional data are needed to reduce uncertainty in the saturation concentration of glycolic acid in 

humans. Although in vitro data suggested that humans may metabolize glycolic acid more efficiently 

than rats (Corley et al. 2005; Booth et al. 2004), there are no in vivo human data to confirm this 

observation. 

Methods for Reducing Toxic Effects. No studies were found describing methods to reduce peak 

absorption of ethylene glycol after inhalation exposure. After oral exposure, gastric lavage and possibly 

activated charcoal may be of benefit in reducing absorption, but only if performed within 1–2 hours 

following ingestion (Barceloux et al. 1999; Egbert and Abraham 1999; Leth and Gregersen 2005). 

Dermal absorption can be minimized through washing the skin with soap to remove any existing ethylene 

glycol. Copious irrigation with water or saline can aid in ocular decontamination. 

Clinical procedures for treating ethylene glycol poisoning focus on reducing the body burden of ethylene 

glycol and its toxic metabolites, interference with toxic metabolite formation (which results in increased 

urinary excretion of parent compound), increased elimination of toxic metabolites produced, reduction of 
 

 

 

 

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metabolic acidosis, and prevention of kidney failure. Procedures include administration of antidotes 

(ethanol or fomepizole), intravenous bicarbonate and hydration for profound acidemia, and hemodialysis 

for refractory acidosis (Barceloux et al. 1999; Egbert and Abraham 1999; Gardner et al. 2004; Leth and 

Gregersen 2005; Scalley et al. 2002). 

Antidotes for ethylene glycol include the alcohol dehydrogenase inhibitors, ethanol and fomepizole, 

which act to decrease the alcohol dehydrogenase-catalyzed metabolism of ethylene glycol, thus 

effectively increasing the urinary excretion of ethylene glycol (Barceloux et al. 1999; Egbert and 

Abraham 1999; Gardner et al. 2004; Leth and Gregersen 2005). 

Intravenous fluid administration may be initiated early to increase urine output, which effectively 

increases the excretion of ethylene glycol and toxic metabolites such as glycolic and oxalic acids (Egbert 

and Abraham 1999). Sodium bicarbonate infusion is used to correct metabolic acidosis, increase 

elimination of renal glycolic acid, and inhibit the precipitation of calcium oxalate crystals (Egbert and 

Abraham 1999; Leth and Gregersen 2005; Scalley et al. 2002). 

Hemodialysis can effectively remove ethylene glycol and the acid metabolites, glycolic and oxalic acids, 

because they have low molecular weights and do not exhibit protein binding (Egbert and Abraham 1999). 

Thiamine (vitamin B1) and pyroxidine (vitamin B6) are co-factors for the metabolism of ethylene glycol 

and may reduce toxicity by assisting in the formation of relatively nontoxic metabolites (Egbert and 

Abraham 1999; Gardner et al. 2004; Goldfrank et al. 2002; Leth and Gregersen 2005; Scalley et al. 2002). 

However the efficacy of treatment with thiamine and pyroxidine has not been demonstrated in human 

cases of ethylene glycol poisoning. 

There are no documented methods for interfering with mechanisms of action for toxic effects of ethylene 

glycol and its potent metabolites. 

Additional information that might be useful in treating ethylene glycol poisoning include studies designed 

to identify additional methods to reduce the body burden of ethylene glycol and its toxic metabolites and 

studies designed to elucidate methods for interfering with mechanisms of action. 
 

 

 

 

 

 

 

 

 

 

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Children’s Susceptibility. Data needs relating to both prenatal and childhood exposures, and 

developmental effects expressed either prenatally or during childhood, are discussed in detail in the 

Developmental Toxicity subsection above. 

A limited amount of information on health effects of ethylene glycol in children is available from several 

case reports of patients admitted to hospitals for treatment of acute oral poisoning (Baum et al. 1999; 

Boyer et al. 2001; Caravati et al. 2004; Harry et al. 1998). The effects in these pediatric patients were 

largely consistent with the first stage of ethylene glycol poisoning in adults (e.g., central nervous system 

depression, metabolic changes, gastrointestinal upset). Treatment with fomepizole (4-methylpyrazole), 

alone or in combination with other methods, generally mitigated the progression of the clinical course to 

the second and third stages of ethylene glycol poisoning (pronounced metabolic acidosis, 

cardiopulmonary compromise, and renal insufficiency) and led to full recovery. The case reports are 

consistent with an expectation that health effects in children and adults are similar. Although there are no 

known differences in the toxicity of ethylene glycol between adults and children, there is no evidence to 

substantiate the presumption. There is no evidence to indicate that children are likely to be exposed to 

higher or lower amounts of ethylene glycol from everyday living, suggesting that children are perhaps 

equally at risk for non-accidental/non-intentional acute oral exposure and potential toxic side effects. 

Information is lacking on the toxicity of longer duration exposures in children, as well as on 

developmental effects in children. 

No studies are available that describe potential differences in the toxicokinetics or the mechanism of 

action of ethylene glycol in children. Glycolic acid is the major toxic metabolite contributing to 

metabolic acidosis, which is a primary cause of systemic toxicity in children as well as adults following 

exposure to ethylene glycol. Glycolic acid has also been identified as the proximate cause of the 

developmental effects in animals observed with ethylene glycol exposure (NTP-CERHR 2004; Slikker et 

al. 2004). 

Limited mechanistic information suggests that humans may be less sensitive than rodents to the 

developmental effects of ethylene glycol. Two in vitro studies (Booth et al. 2004; Corley et al. 2005) 

suggested that humans metabolize glycolic acid more efficiently than rats, although the data supporting 

the glycolic acid metabolic rate in humans are limited (NTP-CERHR 2004). Additionally, NTP-CERHR 

(2004) reviewed preliminary data indicating that the inverted yolk sac placenta, a stage in placental 

development that occurs in rats and mice but does not exist in humans or rabbits, tends to concentrate 

weak acids such as glycolic acid in the embryonic fluids. These data suggest enhanced sensitivity to 
 

 

 

 

 

 

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ethylene glycol developmental effects in rodents compared with humans, although NTP-CERHR (2004) 

characterized the available data as inconclusive. 

Ethylene glycol metabolism is known to involve alcohol dehydrogenase and aldehyde dehydrogenase, 

and may also involve cytochrome P450 isozymes (NTP-CERHR 2004). Polymorphisms in the genes 

encoding these enzymes may lead to wide variability in the production and elimination of glycolic acid 

and other metabolites in humans exposed to ethylene glycol, but data quantifying the range of variability 

are not currently available (NTP-CERHR 2004). In addition, fetal and/or placental differences in 

expression of these enzymes over the course of gestation will affect local concentrations of glycolic acid 

and other metabolites to which the developing conceptus is exposed, yet little is known about these 

differences (NTP-CERHR 2004). 

Child health data needs relating to exposure are discussed in Section 6.8.1, Identification of Data Needs: 

Exposures of Children. 

3.12.3 Ongoing Studies 

No relevant health effects studies for ethylene glycol were located in the Federal Research in Progress 

database (FEDRIP 2007). However, Corley and coworkers are presently extending the PBPK model for 

ethylene glycol and glycolic acid in rats and humans (Corley et al. 2005) to include glyoxylic acid and 

oxalic acid. 
 

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ETHYLENE GLYCOL 175 

4. CHEMICAL AND PHYSICAL INFORMATION
 

4.1 CHEMICAL IDENTITY
 

Information regarding the chemical identity of ethylene glycol is located in Table 4-1. This information 

includes synonyms, chemical formula and structure, and identification numbers. 

4.2 PHYSICAL AND CHEMICAL PROPERTIES 

Information regarding the physical and chemical properties of ethylene glycol is located in Table 4-2. 
 

 

ETHYLENE GLYCOL 176 

4. CHEMICAL AND PHYSICAL INFORMATION 

Table 4-1. Chemical Identity of Ethylene Glycola 

Characteristic Information 

Chemical name Ethylene glycol 

Synonyms and trade names 1,2-Dihydroxyethane; 1,2-ethandiol; 1,2-ethane-diol; 

2-hydroxyethanol; ethylene alcohol; ethylene dihydrate; glycol; 

monoethylene glycol; MEG; Lutrol-9; Dowtherm Sr 1; Fridex; 

Norkool; Ramp; Tescol; Ucar 17 

Chemical formula C2H6O2 

Chemical structure 

Identification numbers: 

CAS registry 107-21-1 

NIOSH RTECS KW2975000b 

EPA hazardous waste No data 

DOT/UN/NA/IMDG shipping No data 

HSDB 5012 

NCI C00920 

HO 

OH 

a

All information obtained from HSDB 2009 except where noted.

b

NIOSH 2005 

CAS = Chemical Abstracts Service; DOT/UN/NA/IMDG = Department of Transportation/United Nations/North 

America/International Maritime Dangerous Goods Code; EPA = Environmental Protection Agency; 

HSDB = Hazardous Substances Data Bank; NCI = National Cancer Institute; NIOSH = National Institute for 

Occupational Safety and Health; RTECS = Registry of Toxic Effects of Chemical Substances 
 

 

ETHYLENE GLYCOL 177 

4. CHEMICAL AND PHYSICAL INFORMATION 

Table 4-2. Physical and Chemical Properties of Ethylene Glycola 

Property Ethylene glycol 

Molecular weight 62.07 

Color Clear, colorlessb 

Physical state Liquidb 

Melting point -12.69 °Cc 

Boiling point 197.3 °Cc 

Density: 

at 20 °C (g/cm3

) 1.1135d 

Vapor density 2.14 (air=1) 

Odor Odorless 

Odor threshold No data 

Solubility: 

Water at 20 °C Miscible with water 

Organic solvent(s) Soluble in lower aliphatic alcohols, glycerol, acetic acid, acetone; 

slightly soluble in ether; practically insoluble in benzene, chlorinated 

hydrocarbons, petroleum ether, oils. 

Partition coefficients: 

Log Kow -1.36e 

Koc 1 (estimated) 

Vapor pressure at 25 °C 0.089 mm Hg (extrapolated)f 

Henry's law constant at 25 °C 6x10-8 atm-m3/moleg 

Autoignition temperature 398 °C 

Flashpoint 127 °Ch 

Explosive limits 3.20–53%i 

Conversion factors 1 ppm = 2.58 mg/m3 

1 mg/m3 = 0.39 ppm 

a

All information obtained from HSDB 2009, except where noted.

b

Lewis 2001 

c

Lide 2005 d

O'Neil et al. 2001 

e

Hansch et al. 1995 

f

AIChE 1995 

g

Hine and Mookerjee 1975

h

Forkner et al. 2004 

i

Rebsdat and Mayer 2005 
ETHYLENE GLYCOL 178 

4. CHEMICAL AND PHYSICAL INFORMATION 

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ETHYLENE GLYCOL 179 

5. PRODUCTION, IMPORT/EXPORT, USE, AND DISPOSAL 

5.1 PRODUCTION 

Commercial production of ethylene glycol in the United States began in 1925 (McClelland and Rector 

1951; Miller 1966). The reported U.S. production volume was 2.189 million pounds (993 metric tons) 

during that year (McClelland and Rector 1951). Large-scale commercial use of ethylene glycol as an 

antifreeze began in 1930; this use led to a strong demand for ethylene glycol, especially during and after 

World War II (Brown et al. 1980; McClelland and Rector 1951). Production volume information is not 

available for this period. By 1950, the U.S. production volume had risen to 510 million pounds 

(230,000 metric tons) (Brown et al. 1980; McClelland and Rector 1951). Production continued to rise 

steadily, reaching approximately 900,000 metric tons by 1968 (Brown et al. 1980). Ethylene glycol 

production rose more dramatically in late 1960s and early 1970s due to the additional demand for use of 

this substance in the manufacturing of polyester fiber and film (Brown et al. 1980; CMR 1972, 1975). 

Production in 1970 was approximately 1,400,000 metric tons (Brown et al. 1980). Production fluctuated 

between 1,500,000 and 1,800,000 metric tons over the next 18 years, reaching 1,820,000 metric tons by 

1978 (Brown et al. 1980). 

Production volume information is not available for years following 1978; however, production capacity 

data for the 1980s, 1990s, and early 2000s have been located. Total reported U.S. production capacities 

were 2,638,000 metric tons during 1981, 2,820,000 metric tons during 1990, 3,727,000 metric tons during 

2001, and 3,242,000 metric tons during 2008 (CMR 1981, 1990, 2001; SRI 2008). The growth of 

ethylene glycol production capacity over these decades has been attributed to the demand for this 

substance in the manufacture of plastics, especially polyethylene terephthalate (PET) resin bottles (CMR 

1981, 1987, 1984, 1990, 1993, 1998, 2001, 2004). The companies that produced ethylene glycol in the 

United States, their production sites, and their annual capacities during 2008 (the most recent year for 

which figures are available) are shown in Table 5-1 (SRI 2008). 

Table 5-2 summarizes the number of facilities in each state that manufactured or processed ethylene 

glycol in 2006, the ranges of maximum amounts on site, if reported, and the activities and uses as 

reported in the Toxics Release Inventory (TRI) (TRI06 2008). The data listed in this table should be used 

with caution since only certain types of facilities are required to report. This is not an exhaustive list. 

The first method used in the commercial production of ethylene glycol in the United States was the 

conversion of chlorohydrin to ethylene oxide and subsequent hydrolysis to ethylene glycol (Forkner et al. 
 

 

 

ETHYLENE GLYCOL 180 

5. PRODUCTION, IMPORT/EXPORT, USE, AND DISPOSAL 

Table 5-1. Companies that Produce Ethylene Glycol in the United States 

and Annual Capacities During 2008 

Capacity (million Capacity 

Company Location pounds/year) (metric tons) 

The Dow Chemical Company	 Plaquemine, Louisiana 465 211,000 

Seadrift, Texas 575 260,900 

Taft, Louisiana 1,545 701,000 

Eastman Chemical Company 

Chemicals and Fibers Group Longview, Texas 200 90,740 

Equistar Chemicals, LP Bayport, Texas 580 263,100 

Formosa Plastics Corporation, USA Point Comfort, Texas 660 299,400 

Huntsman LLC 

Huntsman Performance Products Port Neches, Texas 805a 365,200 

Old World Industries, Inc. Pasadena, Texas 695 315,300 

PD Glycol Beaumont, Texas 790 358,400 

Shell Chemical Company Geismar Louisiana 830 376,600 

Total	 7,145 3,242,000 

Source: SRI 2008 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 181 

5. PRODUCTION, IMPORT/EXPORT, USE, AND DISPOSAL 

Table 5-2. Facilities that Produce, Process, or Use Ethylene Glycol 

Minimum Maximum 

Number of amount on site amount on site 

Statea facilities in poundsb in poundsb Activities and usesc 

AK 8 10,000 9,999,999 2, 3, 4, 7, 9, 12 

AL 69 0 99,999,999 1, 2, 3, 6, 7, 8, 9, 10, 11, 12, 13, 14 

AR 43 0 49,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 

AZ 33 0 999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 

CA 168 0 999,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14 

CO 43 0 49,999,999 1, 2, 4, 5, 6, 7, 8, 9, 10, 11, 12 

CT 24 1,000 999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12 

DE 27 0 999,999 1, 5, 6, 7, 8, 10, 11, 12, 13 

FL 64 0 49,999,999 2, 3, 4, 6, 7, 8, 9, 10, 11, 12 

GA 101 0 499,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14 

HI 2 10,000 999,999 12 

IA 75 0 49,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 

ID 27 0 999,999 1, 2, 3, 5, 7, 8, 10, 11, 12 

IL 150 0 499,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 

IN 109 0 499,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 

KS 59 0 999,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 

KY 83 0 49,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14 

LA 114 0 10,000,000,000 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 

MA 64 0 9,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 

MD 45 0 9,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 

ME 18 1,000 999,999 1, 2, 3, 5, 6, 7, 9, 10, 11, 12, 14 

MI 136 0 499,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 

MN 68 0 49,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 

MO 110 0 49,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 

MS 50 0 49,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 

MT 20 1,000 999,999 1, 2, 3, 4, 7, 8, 9, 10, 11, 12 

NC 140 0 49,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 

ND 10 1,000 9,999,999 7, 8, 9, 10, 11, 12 

NE 23 0 9,999,999 2, 3, 4, 7, 8, 9, 10, 11, 12 

NH 22 0 99,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 

NJ 153 0 499,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 

NM 25 100 999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 

NV 15 0 999,999 1, 2, 3, 4, 5, 6, 7, 11, 12, 13 

NY 86 0 99,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 

OH 138 0 99,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 

OK 56 0 9,999,999 1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 182 

5. PRODUCTION, IMPORT/EXPORT, USE, AND DISPOSAL 

Table 5-2. Facilities that Produce, Process, or Use Ethylene Glycol 

Minimum Maximum 

Number of amount on site amount on site 

Statea facilities in poundsb in poundsb Activities and usesc 

OR 44 0 9,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 

PA 121 0 49,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 

PR 47 0 499,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 

RI 31 0 9,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 

SC 108 0 99,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 

SD 5 1,000 99,999 7, 8, 11, 12 

TN 108 0 49,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 

TX 261 0 499,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 

UT 32 100 499,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14 

VA 98 0 499,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 

VT 8 0 99,999 11, 12 

WA 54 0 99,999,999 1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 14 

WI 94 0 99,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 

WV 85 0 10,000,000,000 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 

WY 15 100 9,999,999 2, 3, 4, 7, 9, 10, 11, 12 

a

Post office state abbreviations used 

b

Amounts on site reported by facilities in each state 

c

Activities/Uses: 

1. Produce 6. Impurity 11. Chemical Processing Aid 

2. Import 7. Reactant 12. Manufacturing Aid 

3. Onsite use/processing 8. Formulation Component 13. Ancillary/Other Uses 

4. Sale/Distribution 9. Article Component 14. Process Impurity 

5. Byproduct 10. Repackaging 

Source: TRI06 2008 (Data are from 2006) 
 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 183 

5. PRODUCTION, IMPORT/EXPORT, USE, AND DISPOSAL 

2004; Rebsdat and Mayer 2005). A second method was introduced in 1937, the direct oxidation of 

ethylene to ethylene oxide followed by hydrolysis to ethylene glycol (Brown et al. 1980; CMR 2008; 

Forkner et al. 2004). This soon became the primary method for the production of ethylene glycol and is 

currently the only method used in the United States (Brown et al. 1980; Forkner et al. 2004; Rebsdat and 

Mayer 2005). 

Other methods that have been used to manufacture ethylene glycol include the direct oxidation of 

ethylene and synthesis from carbon monoxide, methanol, hydrogen, and formaldehyde (Forkner et al. 

2004; Rebsdat and Mayer 2005). The methanol and formaldehyde used in the latter method is obtained 

from syngas, which is originally obtained from coal. 

Ethylene oxide is converted to ethylene glycol through uncatalyzed neutral hydrolysis (pH 6–10) in the 

presence of a large excess of water at high temperatures and pressures (Forkner et al. 2004; Rebsdat and 

Mayer 2005). Selectivity of ethylene glycol is 89–91% in this process. The primary byproduct is 

diethylene glycol with higher glycols such as triethylene and tetraethylene glycols formed in smaller 

amounts. The product mixture is fed through a series of evaporators to remove the water and then 

through vacuum distillation for separation and refinement of the individual glycols. 

5.2 IMPORT/EXPORT 

Both U.S. imports and exports of ethylene glycol have increased since the 1970s. Annual ethylene glycol 

imports rose from 29,300 metric tons in 1977 to 289,000 metric tons in 2006, while annual exports rose 

from 56,800 metric tons in 1978 to 573,000 metric tons in 2006 (HSDB 2009; ITA 2007). From 2000 to 

2006, the average annual U.S. import and export quantities were 317,000 and 556,000 metric tons, 

respectively (ITA 2007). Annual U.S. ethylene glycol import and export quantities reported for different 

years are listed in Table 5-3. Over 70% of the ethylene glycol imported into the United States during 

2006 was imported from Saudi Arabia (114,846 metric tons) and Canada (93,669 metric tons) (ITA 

2007). 

5.3 USE 

Ethylene glycol has been used in a wide variety of industrial applications because of its unique chemical 

and physical properties. Ethylene glycol dissolves in water and is miscible in alcohol and acetone, has the 

capacity to hold large amounts of heat before boiling, and lowers the freezing point of water (Lewis 2001; 

O'Neil et al. 2001; Rebsdat and Mayer 2005). In addition, ethylene glycol is hygroscopic (has the ability 
 

ETHYLENE GLYCOL 184 

5. PRODUCTION, IMPORT/EXPORT, USE, AND DISPOSAL 

Table 5-3. U.S. Ethylene Glycol Imports and Exports by Year in Metric Tons 

Year Imports Exports Reference 

1977 29,300 NA HSDB 2007 

1978 NA 56,800 HSDB 2007 

1982 17,000 NA HSDB 2007 

1983 NA 31,600 HSDB 2007 

1985 130,000 270,000 HSDB 2007 

1986 156,980 NA CMR 1987 

1989 167,869 NA CMR 1990 

1994 239,000 423,000 CMR 1996 

1997 172,000 898,000 CMR 1998 

2000 287,000 534,000 ITA 2007 

2001 332,000 334,000 ITA 2007 

2002 363,000 527,000 ITA 2007 

2003 316,000 660,000 ITA 2007 

2004 277,000 724,000 ITA 2007 

2005 351,000 540,000 ITA 2007 

2006 289,000 573,000 ITA 2007 

NA = not available 
 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 185 

5. PRODUCTION, IMPORT/EXPORT, USE, AND DISPOSAL 

to absorb twice its weight in water), is suitable for use as an industrial humectant (drying agent), and 

possesses excellent solvent properties (Forkner et al. 2004; Lewis 2001; O'Neil et al. 2001). 

Approximately 35% of all ethylene glycol produced is used to make PET solid-state resins, 26% is used 

in antifreeze, 24% is used to make polyester fibers, 4% is used to make polyester film, 3% is used in PET 

chip resin exports, and 8% is used in surface coatings, polyester and alkyd resins, chemical intermediates, 

and other miscellaneous industrial applications (CMR 2004). 

Ethylene glycol plays an essential role in the transportation industry, where it is used as an ingredient in 

hydraulic brake fluids, as the major component in automotive antifreeze/coolant, and as a component of 

de-icing fluids for aircraft, runways, and taxiways (Forkner et al. 2004; Lewis 2001; O'Neil et al. 2001; 

Rebsdat and Mayer 2005). Another important industrial use for ethylene glycol is as an intermediate in 

the synthesis of esters, ethers, and resinous products, particularly polyester fibers and resins (O'Neil et al. 

2001; Rowe and Wolf 1982). As a solvent, ethylene glycol is used in the paint and plastic industries in 

the formulation of printers' inks, stamp pad inks, and inks for ball point pens, and as a softening agent in 

cellophane (O'Neil et al. 2001). Ethylene glycol has also been used as a stabilizer for soy bean foam used 

in fire extinguishers and in the manufacture of explosives, plasticizers, elastomers, and synthetic waxes 

(Lewis 2001; O'Neil et al. 2001). According to Browning (1965), small amounts of ethylene glycol have 

been used in pharmaceutical preparations (components of skin lotions and powders, and as a substitute for 

glycerin); more recent information describing this use has not been located. 

5.4 DISPOSAL 

Two promising methods for the complete (>99%) destruction of ethylene glycol in waste water are 

ultraviolet (UV) light-catalyzed oxidation and supercritical oxidation. In the UV light-catalyzed 

oxidation method, ethylene glycol-containing waste water in the presence of 10% hydrogen peroxide is 

oxidized by UV irradiation (200–250 nm) with light from a mercury lamp (DOE 1993b). The 

UV/hydrogen peroxide undergoes photochemical decomposition to produce OH radicals that are strong 

oxidants capable of oxidizing most organic compounds stepwise to complete mineralization (e.g., carbon 

dioxide and water). In the supercritical water oxidation method, the waste water is subjected to oxidation 

at >550 °C and 4,000 psi pressure with a residence time of <30 seconds (DOE 1993a). 

A new technology, in situ vitrification (a thermal treatment technology) (Drajun 1991), has shown 

potential for the remediation of soil contaminated with ethylene glycol. During the in situ vitrification 

process, contaminated soil is transformed into silicate glass using large amounts of electrical energy and a 
 

 

ETHYLENE GLYCOL 186 

5. PRODUCTION, IMPORT/EXPORT, USE, AND DISPOSAL 

crystalline product similar to obsidian is formed. Another novel approach involving an encapsulated 

biooxidation method proposes that sodium percarbonate encapsulated in polyvinylidene chloride be 

inserted in subsurface soil by a method called hydraulic fracturing. Oxygen slowly released from the 

encapsulated sodium percarbonate increases the number of glycol-degrading organisms. This method is 

expected to remediate soils contaminated with glycols via enhanced aerobic biodegradation in subsurface 

soils (Vesper et al. 1994). 

Distillation of used automobile and heavy duty engine coolant under reduced pressure has been assessed 

to be an acceptable technology for recycling ethylene glycol in terms of economic potential, waste 

reduction potential, and product quality that meets both American Society for Testing and Materials 

(ASTM) and SAE standards (EPA 1993d). 
 

 

 

 

 

 

ETHYLENE GLYCOL 187 

6. POTENTIAL FOR HUMAN EXPOSURE 

6.1 OVERVIEW 

Ethylene glycol has been identified in at least 37 of the 1,689 hazardous waste sites that have been 

proposed for inclusion on the EPA National Priorities List (NPL) (HazDat 2007). However, the number 

of sites evaluated for ethylene glycol is not known. The frequency of these sites can be seen in 

Figure 6-1. 

Two promising methods for the complete (>99%) destruction of ethylene glycol in waste water are 

ultraviolet (UV) light-catalyzed oxidation and supercritical oxidation. In the UV light-catalyzed 

oxidation method, ethylene glycol-containing waste water in the presence of 10% hydrogen peroxide is 

oxidized by UV irradiation (200–250 nm) with light from a mercury lamp (DOE 1993b). The 

UV/hydrogen peroxide undergoes photochemical decomposition to produce OH radicals that are strong 

oxidants capable of oxidizing most organic compounds stepwise to complete mineralization (e.g., carbon 

dioxide and water). In the supercritical water oxidation method, the waste water is subjected to oxidation 

at >550 °C and 4,000 psi pressure with a residence time of <30 seconds (DOE 1993a). 

A new technology, in situ vitrification (a thermal treatment technology) (Drajun 1991), has shown 

potential for the remediation of soil contaminated with ethylene glycol. During the in situ vitrification 

process, contaminated soil is transformed into silicate glass using large amounts of electrical energy and a 

crystalline product similar to obsidian is formed. Another novel approach involving an encapsulated 

biooxidation method proposes that sodium percarbonate encapsulated in polyvinylidene chloride be 

inserted in subsurface soil by a method called hydraulic fracturing. Oxygen slowly released from the 

encapsulated sodium percarbonate increases the number of glycol-degrading organisms. This method is 

expected to remediate soils contaminated with glycols via enhanced aerobic biodegradation in subsurface 

soils (Vesper et al. 1994). 

Distillation of used automobile and heavy duty engine coolant under reduced pressure has been assessed 

to be an acceptable technology for recycling ethylene glycol in terms of economic potential, waste 

reduction potential, and product quality that meets both American Society for Testing and Materials 

(ASTM) and SAE standards (EPA 1993d). 
ETHYLENE GLYCOL 188 

6. POTENTIAL FOR HUMAN EXPOSURE 

Figure 6-1. Frequency of NPL Sites with Ethylene Glycol Contamination 
 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 189 

6. POTENTIAL FOR HUMAN EXPOSURE 

6.2 RELEASES TO THE ENVIRONMENT 

The Toxics Release Inventory (TRI) data should be used with caution because only certain types of 

facilities are required to report (EPA 2005). This is not an exhaustive list. Manufacturing and processing 

facilities are required to report information to the TRI only if they employ 10 or more full-time 

employees; if their facility is included in Standard Industrial Classification (SIC) Codes 10 (except 1011, 

1081, and 1094), 12 (except 1241), 20–39, 4911 (limited to facilities that combust coal and/or oil for the 

purpose of generating electricity for distribution in commerce), 4931 (limited to facilities that combust 

coal and/or oil for the purpose of generating electricity for distribution in commerce), 4939 (limited to 

facilities that combust coal and/or oil for the purpose of generating electricity for distribution in 

commerce), 4953 (limited to facilities regulated under RCRA Subtitle C, 42 U.S.C. section 6921 et seq.), 

5169, 5171, and 7389 (limited S.C. section 6921 et seq.), 5169, 5171, and 7389 (limited to facilities 

primarily engaged in solvents recovery services on a contract or fee basis); and if their facility produces, 

imports, or processes ≥25,000 pounds of any TRI chemical or otherwise uses >10,000 pounds of a TRI

chemical in a calendar year (EPA 2005). 

6.2.1 Air 

Estimated releases of 3.1 million pounds (1,400 metric tons) of ethylene glycol to the atmosphere from 

1,454domestic manufacturing and processing facilities in 2006, accounted for about 41% of the estimated 

total environmental releases from facilities required to report to the TRI (TRI06 2008). These releases are 

summarized in Table 6-1. 

During the application of de-icing solutions to aircraft, an estimated 49–80% of de-icing solutions 

containing ethylene glycol are released on airport runway aprons. The remainder is retained on the 

aircraft or is immediately dispersed to the air (Sills and Blakeslee 1992). 

Ethylene glycol has been identified in air samples collected at 2 of the 37 NPL hazardous waste sites 

where it was detected in some environmental media (HazDat 2007). 
 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 190 

6. POTENTIAL FOR HUMAN EXPOSURE 

Table 6-1. Releases to the Environment from Facilities that Produce, Process, or
 

Use Ethylene Glycola
 

Reported amounts released in pounds per yearb 

Total release 

On- and offStatec RFd Aire Waterf UIg Landh Otheri On-sitej Off-sitek site 

AK 3 54 No data 0 0 0 54 0 54 

AL 30 49,624 219 0 104,418 1,867 154,008 2,120 156,128 

AR 9 11,603 40 9,931 1,030 0 21,624 980 22,604 

AZ 12 19,755 No data 0 0 0 19,755 0 19,755 

CA 85 65,434 8 237 97,403 1,148 144,114 20,115 164,229 

CO 15 6,468 812 0 5 684 7,285 684 7,969 

CT 10 1,492 5 0 0 0 1,497 0 1,497 

DE 3 156 No data 0 0 250 156 250 406 

FL 33 17,500 0 0 8,637 0 17,500 8,637 26,137 

GA 59 10,273 1,705 0 8,437 1,189 14,113 7,491 21,604 

IA 29 11,033 1,430 0 460 2,258 12,463 2,718 15,181 

ID 3 9 No data 0 22,074 0 22,063 20 22,083 

IL 87 56,055 8,704 0 57,990 244 64,825 58,168 122,993 

IN 49 29,895 24,005 810 237,458 655 58,515 234,308 292,822 

KS 17 10,438 0 0 0 0 10,438 0 10,438 

KY 29 7,253 17,215 0 3,511 0 24,468 3,511 27,979 

LA 48 56,501 17,324 21,687 238,430 0 315,521 18,421 333,942 

MA 24 16,574 0 0 133 2,670 16,574 2,803 19,377 

MD 16 3,299 No data 0 280 0 3,299 280 3,579 

ME 2 1,370 2,300 0 750 0 3,670 750 4,420 

MI 58 26,211 920 0 115,219 20,865 28,407 134,808 163,215 

MN 34 10,629 7,492 0 4 13,205 18,121 13,209 31,330 

MO 41 4,284 0 0 43 293 4,327 293 4,620 

MS 11 55,647 30,005 0 1,643 0 85,652 1,643 87,296 

MT 7 2,865 990 0 19,469 144 23,279 189 23,468 

NC 59 438,298 15,741 0 83,059 9,130 454,469 91,759 546,228 

ND 5 0 0 0 45,800 0 45,800 0 45,800 

NE 11 3,018 0 0 1,316 32 3,268 1,098 4,366 

NH 2 0 No data 0 0 0 0 0 0 

NJ 42 10,196 2,663 0 2,192 4,463 12,983 6,531 19,514 

NM 9 2,423 5 2,594 0 3,156 2,428 5,750 8,178 

NV 6 6 No data 0 112,586 0 112,592 0 112,592 

NY 28 3,098 4,780 0 20,087 6,400 27,383 6,982 34,365 

OH 93 83,662 16,809 357,322 38,018 8,833 456,593 48,051 504,643 
 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 191 

6. POTENTIAL FOR HUMAN EXPOSURE 

Table 6-1. Releases to the Environment from Facilities that Produce, Process, or
 

Use Ethylene Glycola
 

Reported amounts released in pounds per yearb 

Total release 

On- and offStatec RFd Aire Waterf UIg Landh Otheri On-sitej Off-sitek site 

OK 32 94,801 0 750 31,193 819 125,987 1,576 127,563 

OR 16 8,087 5 0 0 10 8,092 10 8,102 

PA 68 55,282 3,388 0 16,751 138,419 67,409 146,430 213,840 

PR 10 2,285 No data 0 100 321 2,285 421 2,706 

RI 7 1,192 0 0 2,210 0 1,192 2,210 3,402 

SC 52 511,500 39,405 0 736,820 42,112 550,905 778,932 1,329,837 

SD 1 0 No data 0 0 0 0 0 0 

TN 25 262,245 247,371 0 91,085 0 516,191 84,510 600,701 

TX 158 454,959 50,198 914,240 114,001 1,905 924,881 610,422 1,535,303 

UT 11 7,706 0 0 71,169 385 78,802 458 79,260 

VA 28 459,257 455 0 28 2,700 459,712 2,728 462,440 

VT 1 0 300 0 0 302 300 302 602 

WA 14 8,305 0 0 468 2,589 8,305 3,057 11,362 

WI 41 107,031 54 0 2,280 3,021 107,085 5,301 112,386 

WV 15 97,225 96 0 87,843 80 148,388 36,856 185,244 

WY 6 25 No data 13,836 32 0 13,861 32 13,893 

Total 1,454 3,085,022 494,445 1,321,407 2,374,430 270,149 5,200,639 2,344,813 7,545,453 

a

The TRI data should be used with caution since only certain types of facilities are required to report. This is not an 

exhaustive list. Data are rounded to nearest whole number.
 b

Data in TRI are maximum amounts released by each facility.
 c

Post office state abbreviations are used.
 d

Number of reporting facilities.
 e

The sum of fugitive and point source releases are included in releases to air by a given facility.
 f

Surface water discharges, waste water treatment-(metals only), and publicly owned treatment works (POTWs) (metal
 

and metal compounds).
 g

Class I wells, Class II-V wells, and underground injection. h

Resource Conservation and Recovery Act (RCRA) subtitle C landfills; other on-site landfills, land treatment, surface 

impoundments, other land disposal, other landfills.

i

Storage only, solidification/stabilization (metals only), other off-site management, transfers to waste broker for
 

disposal, unknown

j

The sum of all releases of the chemical to air, land, water, and underground injection wells.

k

Total amount of chemical transferred off-site, including to POTWs.
 

RF = reporting facilities; UI = underground injection 

Source: TRI06 2008 (Data are from 2006) 
 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 192 

6. POTENTIAL FOR HUMAN EXPOSURE 

6.2.2 Water 

Estimated releases of 0.5 million pounds (220 metric tons) of ethylene glycol to surface water from 

1,454 domestic manufacturing and processing facilities in 2006, accounted for about 6.5% of the 

estimated total environmental releases from facilities required to report to the TRI (TRI06 2008). 

Ethylene glycol is released to surface waters in waste water from production and processing facilities, 

from spills, in runoff (e.g., through the use of the compounds as de-icing fluids), and in the disposal of 

used antifreeze (Christian and Moorehead 1985; EPA 2000; Ware 1988). Ethylene and propylene glycol 

concentrations up to 19,000 mg/L (ppm) were detected in storm water runoff at the Salt Lake City Airport 

in Utah, and airport runoff was found to contain up to 3,100 mg/L (ppm) at the Toronto International 

Airport in Canada and up to 5,050 mg/L (ppm) at the Denver Airport in Colorado (Sills and Blakeslee 

1992). Ethylene glycol was detected, but not quantified, in effluents from a chemical plant in 

Brandenburg, Kentucky (EPA 1976). 

EPA (2000) estimated that 21 million gallons of aircraft deicing fluid (including both ethylene and 

propylene glycol-based fluids) are discharged to surface waters per year in the United States with an 

additional 2 million gallons discharged to publicly owned treatment works (POTWs). These releases are 

expected to decrease as source reduction technologies and recycling/recovery systems are improved. 

Airports that have updated equipment and collection systems have achieved a 70% collection efficiency 

on average. 

Ethylene glycol that is released onto the ground when used in aircraft de-icing fluid may contaminate 

nearby groundwater (Corsi et al. 2001a). Groundwater samples collected from a perched water table at 

the Ottawa Airport in Canada contained 415 mg/L (ppm) of ethylene glycol (Sills and Blakeslee 1992). 

Ethylene glycol has been identified in surface water and groundwater samples collected at 1 and 7 of the 

37 NPL hazardous waste sites, respectively, where it was detected in some environmental media (HazDat 

2007). 

6.2.3 Soil 

Estimated releases of 2.4 million pounds (1,080 metric tons) of ethylene glycol to soils from 

1,454 domestic manufacturing and processing facilities in 2006, accounted for about 31% of the estimated 

total environmental releases from facilities required to report to the TRI (TRI06 2008). An additional 
 

 

 

 

 

 

 

 

 

 

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1.3 million pounds (600 metric tons), constituting about 17.5% of the total environmental emissions, were 

released via underground injection (TRI06 2008). These releases are summarized in Table 6-1. 

The major sources of ethylene glycol release to soil are from the disposal of used antifreeze fluids and deicing fluids containing this compound (EPA 1979, 1987; Ware 1988). Ethylene glycol may also be 

released to soil via natural processes associated with the metabolism of ethylene by plants (Blomstrom 

and Beyer 1980). 

Ethylene glycol has been identified in soil and sediment samples collected at 2 and 1 of the 37 NPL 

hazardous waste sites, respectively, where it was detected in some environmental media (HazDat 2007). 

6.3 ENVIRONMENTAL FATE 

6.3.1 Transport and Partitioning 

Ethylene glycol has a low vapor pressure (0.089 mm Hg at 25 °C) and is miscible with water (see 

Table 4-2). If released to the atmosphere (e.g., as vapors generated at elevated temperatures), ethylene 

glycol should exist almost entirely in the vapor phase (Eisenreich et al. 1981). The high solubility of 

ethylene glycol in water ensures that at least partial removal of the compound will occur by wet 

deposition. The low Henry's law constant value for this compound (6.00x10-8 atm-m3

/mole, see 

Table 4-2) suggests that ethylene glycol released to surface water will not partition to the atmosphere via 

volatilization (Simmons et al. 1976; Thomas 1990). Ethylene glycol is not expected to adsorb to 

sediment or soil particulates based on an estimated Koc value of 1 (see Table 4-2). Based on the low Koc 

value (see Table 4-2), ethylene glycol is expected to have a very high mobility in soil and could leach into 

groundwater (Swann et al. 1983). 

The low octanol/water partition coefficient (Kow) value of -1.36 (see Table 4-2) suggests that 

bioconcentration and biomagnification of ethylene glycol are not likely to occur. Laboratory testing with 

this compound confirms insignificant bioconcentration in fish (Freitag et al. 1985). The bioconcentration 

factor (BCF) for ethylene glycol in fish (Golden ide) was 10 after 3 days of exposure. 

Ethylene glycol is expected to be highly mobile, particularly in moist soils, and it may leach into 

groundwater upon release to surface soils. In laboratory studies, ethylene glycol was found to percolate 

rapidly through soil columns with little or no adsorption (LA DOTD 1989; Løkke 1984); however, rapid 

biodegradation is expected to limit the extent of leaching through soil (see Section 6.3.2.3). The 
 

 

 

 

 

 

 

 

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compound may also volatilize from dry surface soils (EPA 1979, 1987; Hine and Mookerjee 1975). In 

dry soils, ethylene glycol liquid can enter the soil system and travel through the porous media before 

contacting free water. Amoozegar et al. (1986) reported that in dry soils (<1% water) the rate of ethylene 

glycol movement was the slowest of 6 organic liquids tested (toluene, xylene, kerosene, acetone, and 

isopropyl alcohol). 

6.3.2 Transformation and Degradation 

6.3.2.1 Air 

Ethylene glycol released to the atmosphere is expected to undergo rapid photochemical oxidation via 

reaction with hydroxyl radicals. The half-life for the photochemical oxidation of ethylene glycol is 

1.4 days calculated using a measured reaction rate constant of 7.7x10-12 cm3

/molecule-second at 25 °C, 

assuming a 12-hour day and an average day-light atmospheric hydroxyl radical concentration of 

1.5x106 radicals/cm3 (Atkinson 1989; EPA 1993e). Direct photolysis of ethylene glycol is not expected 

since alcohols do not absorb UV light at environmental wavelengths (above 295 nm) (Boethling and 

Mackay 2000). 

6.3.2.2 Water 

Biodegradation is the most important transformation process for ethylene glycol in surface waters under 

both aerobic and anaerobic conditions (Staples et al. 2001). In screening tests using aerobic sewage 

sludge inocula, the incubation time for the majority of the biodegradation of ethylene glycol to take place 

ranges from within a day to a few weeks (Bridie et al. 1979; Conway et al. 1983; Ettinger 1956; 

Heukelekian and Rand 1955; Lamb and Jenkins 1952; Means and Anderson 1981; Pitter 1976; Price et al. 

1974; Slave et al. 1974; Wagner 1976; Young et al. 1968). Evans and David (1974) performed river 

die-away tests in which ethylene glycol, added to river water at concentrations ≤10mg/L (ppm), was 

completely biodegraded after 3 days at 20 °C and after 14 days at 8 °C. 

Other reports of biotransformation of ethylene glycol include anaerobic metabolism (Battersby and 

Wilson 1989; Bieszkiewicz et al. 1979; Dwyer and Tiedje 1983; Hovious et al. 1973; Kameya et al. 1995; 

Watson and Jones 1977). Based on available data, ethylene glycol appears to be completely degraded 

within 1–2 weeks under anaerobic conditions (Battersby and Wilson 1989; Dwyer and Tiedje 1983; 

Kameya et al. 1995). Schoenberg et al. (2001) measured first-order biodegradation rate constants of 3.5– 

5.2 per day for ethylene glycol-based deicing fluids under anaerobic conditions, corresponding to half-
 

 

 

 

 

 

 

 

 

 

 

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lives of <1 day. Dwyer and Tiedje (1983) proposed that the methanogenic degradation pathway proceeds 

through formation of ethanol followed by acetate. 

Waste water carrying ethylene glycol can be purified using the activated sludge method provided the 

concentration of ethylene glycol does not exceed 1,000 mg/L (ppm) (Bieszkiewicz et al. 1979). Similar 

results were observed for the degradation of ethylene glycol in groundwater (McGahey and Bouwer 

1992). At an initial substrate concentration of 111 mg/L (ppm), naturally occurring microorganisms in 

groundwater biodegraded ethylene glycol with a calculated half-life of <1 day following a lag phase of 

<3 days. 

Ethylene glycol is not expected to undergo significant abiotic transformation in surface waters via 

hydrolysis or oxidation (EPA 1979; Harris 1990). Glycols are resistant to hydrolysis (Harris 1990). 

Ethylene glycol is not expected to undergo direct photolysis in sunlit waters since alcohols do not absorb 

UV light at environmental wavelengths (above 295 nm) (Boethling and Mackay 2000). However, 

indirect photolysis of ethylene glycol sorbed to goethite (a common natural constituent of surface water 

sediments) by near ultraviolet radiation (300–400 nm) has been demonstrated in the laboratory. 

Formaldehyde and glycolaldehyde were detected as degradation products (Cunningham et al. 1985). 

6.3.2.3 Sediment and Soil 

Biodegradation under both aerobic and anaerobic conditions is also the most important transformation 

process for ethylene glycol in soils, with half-lives similar to or less than those measured in surface waters 

(EPA 1987). 

The rate of biodegradation of ethylene glycol in simulated subsurface soils is dependent on substrate 

concentrations, soil types, and ambient soil temperatures (McGahey and Bouwer 1992). Greater than 

95% removal was consistently accomplished in <5 days and 7 days at ethylene glycol concentrations of 

100 and 1,000 ppm, respectively; however, substrate concentrations of 10,000 ppm showed negligible 

loss of ethylene glycol. The rate of degradation was higher in soils with high organic matter. A doubling 

in the degradation rate was also observed with a 10 °C increase in soil temperature. McGahey and 

Bouwer (1992) concluded that microorganisms naturally occurring in soils and groundwater are effective 

in biodegrading ethylene glycol with the half-life ranging from 0.2 to 0.9 days. Approximately 23–26% 

of ethylene glycol at 2.25 ppm was biodegraded in anaerobic sandy till soil grab sample tests run for 

86 and 140 days (Løkke 1984). 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Klecka et al. (1993) studied the biodegradation of aircraft de-icing fluids in soils adjacent to airport 

runways at various ethylene glycol concentrations and at various temperatures ranging from -2 to 25 °C. 

Generally, the rate of biodegradation of ethylene glycol was faster in soils with low glycol concentrations, 

high organic carbon content, and higher ambient soil temperatures. Ethylene glycol present in soils at 

concentrations <6,000 mg/kg (ppm) biodegraded at an average rate of 3.0 mg/kg (ppm) soil/day at -2 °C, 

at 19.7 mg/kg (ppm) soil/day at 8 °C, and at an average rate of 66.3 mg/kg (ppm) soil/day at 25 °C 

(Klecka et al. 1993). Based on these results, biodegradation is expected to play a major role in removing 

ethylene glycol residues from soils adjacent to airport runways and taxiways. Revitt and Worrall (2003) 

measured first-order biodegradation rate constants of 0.064 day-1 at 1 °C, 0.082 day-1 at 4 °C, and 

0.091 day-1 at 8 °C for an ethylene glycol-diethylene glycol de-icing formulation on paving blocks taken 

from an airport. These rates correspond to half-lives of 10.8, 8.5, and 7.6 days, respectively. 

As in surface waters, abiotic transformation of ethylene glycol in soil is not expected to be a significant 

process (EPA 1987). 

6.4 LEVELS MONITORED OR ESTIMATED IN THE ENVIRONMENT 

Reliable evaluation of the potential for human exposure to ethylene glycol depends in part on the 

reliability of supporting analytical data from environmental samples and biological specimens. 

Concentrations of ethylene glycol in unpolluted atmospheres and in pristine surface waters are often so 

low as to be near the limits of current analytical methods. In reviewing data on ethylene glycol levels 

monitored or estimated in the environment, it should also be noted that the amount of chemical identified 

analytically is not necessarily equivalent to the amount that is bioavailable. The analytical methods 

available for monitoring ethylene glycol in a variety of environmental media are detailed in Chapter 7. 

6.4.1 Air 

Ethylene glycol was detected in ambient air samples, at time-weighted average (TWA) concentrations of 

<0.05–0.33 mg/m3 as aerosol and <0.05–10.4 mg/m3 as vapor, following spray application of de-icing 

fluids containing 50% solutions of the compound to the surfaces of bridges. The ambient air samples 

were collected above the sprayed bridges (LA DOTD 1989). Ethylene glycol was detected as a vapor 

above 2.5 mg/m3 in 18 out of 154 air samples collected during de-icing operations at a Montreal airport 

(Gérin et al. 1997). The maximum concentration reported was 22.0 mg/m3

. Three of the air samples 

contained ethylene glycol as a mist at concentrations of 76, 91, and 190 mg/m3

. 
 

 

 

 

 

 

 

 

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Ethylene glycol was identified in air samples collected in four new manufactured houses and seven sitebuilt houses (Hodgson et al. 2000). The range and geometric mean of ethylene glycol concentrations 

were <9.2–43.8 and 17.9 mg/m3

, respectively, in the manufactured houses and 20.7–491 and 2.7 mg/m3, 

respectively, in the site-built houses. Latex paint was indicated as a source for ethylene glycol emissions 

in the new houses. 

Background concentrations of ethylene glycol in ambient air are not available. 

6.4.2 Water 

Monitoring data from several contractor and airport authority reports reveal that storm water runoff from 

airports may contain several hundred to several thousand mg/L (ppm) glycols (Sills and Blakeslee 1992). 

Ethylene and propylene glycol levels up to 19,000 mg/L (ppm) were detected in storm water from the Salt 

Lake City International Airport. The concentration of ethylene glycol in runoff from runway apron areas 

at the Toronto International Airport ranged from 75.0 mg/L to 3,100 mg/L (ppm) and was up to 70 mg/L 

(ppm) in a stream that received runoff from the airport. Ethylene glycol concentrations ranged from 2 to 

660 mg/L (ppm) and from 5 to 170 mg/L (ppm) in streams flowing through Winnipeg International 

Airport and St. John's International Airport (Newfoundland), respectively (Environment Canada 2000). 

Ethylene glycol concentrations were less than the detection limit (25 mg/L) in Etobicoke Creek, which 

receives storm water from Lester B. Pearson International Airport in Toronto. The concentration of 

ethylene glycol in storm water runoff from Stapleton International Airport in Denver, Colorado ranged 

from near zero to 5,050 mg/L (ppm) (Sills and Blakeslee 1992). Although the potential for groundwater 

contamination is quite low for many airports with predominantly heavy soil, the movement of glycols 

through unsaturated silty sand can be potentially high (Sills and Blakeslee 1992). Thus, although 

ethylene glycol was not detected even in shallow soils at the edge of the runway at the Stapleton 

International Airport, the groundwater in the perched water table at Ottawa International Airport in 

Canada, which contained sandy soil, was found to contain ethylene glycol at levels up to 415 mg/L 

(ppm). Peak concentrations occurred in June and declined to nondetectable levels by the fall. 

No information was found regarding background concentrations of ethylene glycol in surface water, 

groundwater, or drinking water. 
 

 

 

 

 

 

 

ETHYLENE GLYCOL 198 

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6.4.3 Sediment and Soil 

No information was found regarding the concentrations of ethylene glycol in soil or sediment. 

6.4.4 Other Environmental Media 

Ethylene glycol has been found to migrate into a number of foods from regenerated cellulose films 

containing triethylene glycol and polyethylene glycol as softening agents. Ethylene glycol was detected 

in fruit cakes at 27–34 mg/kg (ppm) after 84–336 days of storage, in meat pies at <10 mg/kg (ppm) after 

3–7 days of storage, in toffee at <10–22 mg/kg (ppm) after 168–450 days of storage, in madeira cake at 

<10–22 mg/kg (ppm) after 21–28 days storage, and in boiled sweets at 14–34 mg/kg (ppm) after 168– 

450 days storage (Castle et al. 1988a). According to Kashtock and Breder (1980), ethylene glycol can 

migrate into food simulants from polyethylene terephthalate (PET) bottles used in the packaging of 

carbonated beverages. The compound was detected at a concentration of about 100 ppb (0.1 ppm) in a 

3% acetic acid solution used as a food simulant after 6 months of storage at 32 °C (Kashtock and Breder 

1980). These authors stated that the source of ethylene glycol in this food simulant is the small amount of 

unreacted ethylene glycol in the polyethylene terephthalate polymer. More recent information regarding 

levels of ethylene glycol in food is not available. 

Ethylene glycol has been identified in negligible amounts in the water-soluble component of cigarette 

smoke (Schumacher et al. 1977). 

6.5 GENERAL POPULATION AND OCCUPATIONAL EXPOSURE 

Ethylene glycol concentrations in blood, urine, tissue, or breast milk are not available for the general 

population in the United States. The most common route of human exposure to ethylene glycol for 

members of the general population is dermal contact with ethylene glycol-based automobile antifreeze. 

However, intentional or accidental ingestion of antifreeze is the most serious type of exposure, resulting 

in thousands of ethylene glycol poisonings including several deaths reported each year in the United 

States (Fraser 2002; Leth and Gregersen 2005). 

Exposure to ethylene glycol through consumption of foods or drinks stored in plastics made from this 

chemical may be possible if the plastic contains unreacted ethylene glycol that can migrate into the food 

(Kashtock and Breder 1980). However, current levels of ethylene glycol in food have not been located; 
 

 

 

 

 

 

 

 

 

 

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therefore, evidence is not available to indicate that this as an important route of human exposure to 

ethylene glycol. 

Background concentrations of ethylene glycol in air, surface water, groundwater, drinking water, soil, and 

sediment are not available. Ethylene glycol is not expected to be found in the environment away from 

areas where it is released since this substance is degraded within days to a few weeks in air, water, and 

soil. Therefore, inhalation of ambient air, ingestion of drinking water, and dermal contact with water or 

soil are not expected to be important routes of exposure of the general population to ethylene glycol. 

Contact with the skin and eyes is the most likely route of worker exposure to ethylene glycol. Inhalation 

may be an important route of human exposure under occupational conditions where the compound is 

heated or if mists are generated by heat or violent agitation (Rowe and Wolf 1982). Individuals involved 

in airport de-icing operations are exposed to ethylene glycol through inhalation since the de-icing 

formulation is sprayed through the air, generating ethylene glycol vapor and mist. Dermal exposure to 

ethylene glycol in deicing fluids may also be important, especially for workers who do not have adequate 

skin protection during or after application (Leggat and Smith 2006; Upadhyay et al. 2008). 

Gérin et al. (1997) measured urinary ethylene glycol concentrations for 33 aviation workers exposed to 

de-icing fluid over a winter period of 2 months. Ethylene glycol was detected above 2.5 mg/m3 (limit of 

quantification) as vapor in only 18 out of 154 air samples collected during spray operations. Reported 

concentrations ranged from 0.9 to 22 mg/m3

. Ethylene glycol was also detected as a mist in three of the 

air samples with concentrations of 76, 91, and 190 mg/m3

. Ethylene glycol quantities in post-shift and 

next-morning urine samples exceeded 5 mmol/mol creatinine in 16 of the 33 workers (5.2–129 mmol/mol 

creatinine). Exposure was greatest for basket operators and coordinators. Air samples taken from the 

breathing zones of workers applying de-icing fluids (50% ethylene glycol) to bridge surfaces contained 

the compound at concentrations of <0.05–2.33 mg/m3 as aerosols and <0.05–3.37 mg/m3 as vapors 

(LA DOTD 1989). 

Laitinen et al. (1995) measured urinary ethylene glycol concentrations in 10 car mechanics frequently 

exposed to ethylene glycol and a control group of 10 male office workers. Levels were noticeably higher 

in the urine of the mechanics. Ethylene glycol and oxalic acid concentrations were 7.3 and 47 mmol/mol 

creatinine, respectively, in the urine of the car mechanics and 1.7 and 36 mmol/mol creatinine, 

respectively, in the urine of the controls. Ethylene glycol concentrations in the air of the mechanics' 

environment were negligible. A health hazard evaluation of a newspress facility in Buffalo, New York 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 200 

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found that concentrations of ethylene glycol in air were below occupational exposure criteria 

(<0.50 mg/m3

); however, dermal exposure to ethylene-glycol-containing solvent washes was reported to 

be a significant route of exposure for employees (NIOSH 2006). Letzel et al. (2000) reported mean and 

median ethylene glycol concentrations of 0.31 and 0.23 mg/L, respectively, measured in the urine of 

16 individuals living in Germany who had no known occupational exposure to glycols. 

The National Occupational Exposure Survey (NOES) conducted by NIOSH during 1981–1983 estimated 

that 1.5 million workers are potentially exposed to ethylene glycol each year (NIOSH 1990). 

6.6 EXPOSURES OF CHILDREN 

This section focuses on exposures from conception to maturity at 18 years in humans. Differences from 

adults in susceptibility to hazardous substances are discussed in Section 3.7, Children’s Susceptibility. 

Children are not small adults. A child’s exposure may differ from an adult’s exposure in many ways. 

Children drink more fluids, eat more food, breathe more air per kilogram of body weight, and have a 

larger skin surface in proportion to their body volume. A child’s diet often differs from that of adults. 

The developing human’s source of nutrition changes with age: from placental nourishment to breast milk 

or formula to the diet of older children who eat more of certain types of foods than adults. A child’s 

behavior and lifestyle also influence exposure. Children crawl on the floor, put things in their mouths, 

sometimes eat inappropriate things (such as dirt or paint chips), and spend more time outdoors. Children 

also are closer to the ground, and they do not use the judgment of adults to avoid hazards (NRC 1993). 

Ethylene glycol antifreeze is a brightly-colored liquid and can be confused for a beverage, especially 

when it is not kept in its original container (Leth and Gregersen 2005). The sweet taste of ethylene glycol 

adds to this attraction. For this reason, some states have mandated that the bittering agent, denatonium 

benzoate, be added to ethylene glycol antifreeze formulations (Hogue 2006; White et al. 2008). Although 

the presence of a bittering agent is expected to deter children from accidentally ingesting ethylene glycolbased antifreeze, caution should still be used. Harry et al. (1998) reported a case of accidental ingestion 

of ethylene glycol antifreeze by a 4-year-old child even though the formulation contained denatonium 

benzoate. 

Many ethylene glycol poisonings occur when an antifreeze bottle is in use (EPA 2004b; Leth and 

Gregersen 2005; Schwerk et al. 2007). Children may touch or ingest ethylene glycol from an opened 
 

 

 

 

 

ETHYLENE GLYCOL 201 

6. POTENTIAL FOR HUMAN EXPOSURE 

container of antifreeze that an adult has placed within reach. Children may also play with a puddle of 

antifreeze that has been spilled onto the ground. 

Children who live near facilities that manufacture or use ethylene glycol may be exposed to this substance 

through contact with contaminated soil or water. Children living near airports where ethylene glycol is 

used in de-icing operations may be exposed through ingestion of contaminated groundwater or inhalation 

of ethylene glycol vapor. 

Biomonitoring data for children, including levels of ethylene glycol measured in breast milk, neonatal 

blood, cord blood, and meconium fluid have are not available. A 28-year-old woman who was 26 weeks 

pregnant was admitted to the hospital following ingestion of 400 mL ethylene glycol (Kralova et al. 2006; 

Kuczkowski 2006). The child was delivered immediately via cesarean section. Serum ethylene glycol 

levels measured in the mother and child were 2,480 and 2,206 mg/L, respectively (Kralova et al. 2006). 

6.7 POPULATIONS WITH POTENTIALLY HIGH EXPOSURES 

Workers in industries involved in the manufacture or use of products containing high concentrations of 

ethylene glycol (e.g., antifreeze, coolants, de-icing fluids, brakes fluids, solvents) may be exposed to 

concentrations of the compound at levels higher than the general population, particularly in operations 

involving heating or spraying of these materials. 

Members of the general population who currently have potentially high exposures to ethylene glycol 

include individuals living near sites where ethylene glycol is manufactured or used and individuals living 

near waste disposal sites contaminated with ethylene glycol. Persons living near airports where large 

amounts of ethylene glycol are used for de-icing of aircraft or near hazardous waste sites are potentially at 

greater risk of exposure, particularly from consumption of contaminated groundwater. 

6.8 ADEQUACY OF THE DATABASE 

Section 104(i)(5) of CERCLA, as amended, directs the Administrator of ATSDR (in consultation with the 

Administrator of EPA and agencies and programs of the Public Health Service) to assess whether 

adequate information on the health effects of ethylene glycol is available. Where adequate information is 

not available, ATSDR, in conjunction with NTP, is required to assure the initiation of a program of 

research designed to determine the health effects (and techniques for developing methods to determine 

such health effects) of ethylene glycol. 
 

 

 

 

 

 

 

 

 

 

 

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The following categories of possible data needs have been identified by a joint team of scientists from 

ATSDR, NTP, and EPA. They are defined as substance-specific informational needs that if met would 

reduce the uncertainties of human health assessment. This definition should not be interpreted to mean 

that all data needs discussed in this section must be filled. In the future, the identified data needs will be 

evaluated and prioritized, and a substance-specific research agenda will be proposed. 

6.8.1 Identification of Data Needs 

Physical and Chemical Properties. As seen in Table 4-2, the relevant physical and chemical 

properties of ethylene glycol are known (AIChE 1995; Forkner et al. 2004; Hansch et al. 1995; Hine and 

Mookerjee 1975; HSDB 2009; Lewis 2001; Lide 2005; O'Neil et al. 2001; Rebsdat and Mayer 2005) and 

predicting the environmental fate and transport of ethylene glycol based on these properties is possible. 

No further information is needed. 

Production, Import/Export, Use, Release, and Disposal. According to the Emergency 

Planning and Community Right-to-Know Act of 1986, 42 U.S.C. Section 11023, industries are required 

to submit substance release and off-site transfer information to the EPA. The TRI, which contains this 

information for 2005, became available in February of 2007. This database is updated yearly and should 

provide a list of industrial production facilities and emissions. 

Production, Import/Export, Use, Release, and Disposal. Knowledge of production and use 

data for a chemical is important in predicting its potential for environmental contamination and human 

exposure. Both recent and historical production data are available for ethylene glycol (Brown et al. 1980; 

CMR 1981, 1984, 1987, 1990, 1993, 1998, 2001, 2004; Forkner et al. 2004; McClelland and Rector 1951; 

Miller 1966; Rebsdat and Mayer 2005; SRI 2008). Similarly, data on the import/export volumes for 

ethylene glycol for the last several years are available (HSDB 2009; ITA 2007). Information on the 

various uses of this compound is also available (Browning 1965; CMR 2004; Forkner et al. 2004; Lewis 

2001; O'Neil et al. 2001; Rebsdat and Mayer 2005; SRI 2008). Ethylene glycol enters the environment 

primarily during its use as a component of automotive antifreeze/coolants, as a de-icing fluid for aircraft, 

and as an intermediate in the synthesis of polyester fibers (Klecka et al. 1993; Lewis 2001; O'Neil et al. 

2001; Rowe and Wolf 1982). Major sources of ethylene glycol releases to soils are from the disposal of 

used antifreeze and de-icing solutions in hazardous waste sites (EPA 1979, 1987; Ware 1988). 
 

 

 

 

 

 

 

 

 

 

 

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Information regarding the disposal of ethylene glycol-containing waste waters (DOE 1993a, 1993b) and 

for remediation of ethylene glycol contaminated soils (Drajun 1991; Vesper et al. 1994) is available. 

Environmental Fate. Information regarding the fate of ethylene glycol in the air is available that 

suggests that the compound would be primarily found in the vapor phase and would likely be removed 

from the atmosphere via wet deposition (Eisenreich et al. 1981; EPA 1979). Ethylene glycol undergoes 

rapid photochemical oxidation via reaction with hydroxyl radicals with a half-life of 1.4 hours (Atkinson 

1989; EPA 1993e). Because of its high solubility in water, the compound is expected to be transported 

primarily in aqueous media (EPA 1979) and will not partition to the atmosphere via volatilization from 

water (Thomas 1990). Adsorption to sediment or soil particles is not expected to be significant based on 

the low Koc value; therefore, ethylene glycol is expected to have a high mobility in soil and the potential 

to leach into groundwater (Swann et al. 1983). Ethylene glycol is degraded in both water (Battersby and 

Wilson 1989; Bieszkiewicz et al. 1979; Bridie et al. 1979; Caskey and Taber 1981; Dwyer and Tiedje 

1983; Evans and David 1974) and soil (Klecka et al. 1993; McGahey and Bouwer 1992; Revitt and 

Worrall 2003) primarily by biodegradation. Based on available data, ethylene glycol is biodegraded 

under both aerobic and anaerobic conditions from within a day to a few weeks. No additional information 

on degradation of ethylene glycol in air, water, or soil is required. 

Bioavailability from Environmental Media. Available information regarding the rate of ethylene 

glycol absorption following inhalation, oral, or dermal contact has been discussed in the Toxicokinetics 

section (see Section 3.4). Although no data on ethylene glycol's bioavailability from contaminated air are 

available, the bioavailability from inhalation exposure is expected to be high because ethylene glycol is 

likely to be present in the vapor phase (Eisenreich et al. 1981) and not in the particulate phase in the 

adsorbed state. Similarly, no data on the bioavailability of ethylene glycol from water, soil, or plant 

material are available; however, ethylene glycol is miscible in water and does not adsorb readily to soil. 

Ethylene glycol, therefore, is expected to be readily bioavailable from soil and water. Information on the 

bioavailability of ethylene glycol from actual environmental media needs further development. 

Food Chain Bioaccumulation. Based on its low Koc value, ethylene glycol is not expected to 

bioconcentrate in aquatic food chains. Freitag et al. (1985) reported a BCF value of 10 measured in fish. 

Information is also lacking regarding the biomagnification potential of ethylene glycol through aquatic 

food chains, although biomagnification is probably a minor process because of the rapid degradation rate 

for the chemical in aquatic systems. No further information on the bioconcentration or biomagnification 

potential of ethylene glycol is needed. 
 

 

 

 

 

 

 

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Exposure Levels in Environmental Media. Reliable monitoring data for the levels of ethylene 

glycol in contaminated media at hazardous waste sites are needed so that the information obtained on 

levels of ethylene glycol in the environment can be used in combination with the known body burden of 

ethylene glycol to assess the potential risk of adverse health effects in populations living in the vicinity of 

hazardous waste sites. 

Information on the number of hazardous waste sites on the NPL at which ethylene glycol was detected in 

air, surface water, groundwater, soil, and sediment is available (HazDat 2007). However, more specific 

information, such as concentrations in these media, is needed to give a better indication of the potential 

for human exposure to ethylene glycol in areas near hazardous waste sites. 

No information was located on the concentration of ethylene glycol in ambient air. Time weighted 

average concentrations of the compound as both an aerosol and a vapor were measured following the 

spray application of de-icing fluids containing ethylene glycol on a bridge (LA DOTD 1989) and at an 

airport (Gérin et al. 1997). These data are not general enough to estimate inhalation exposure to ethylene 

glycol for the general population in the United States. No data on the level of ethylene glycol in drinking 

water were located, although ethylene glycol has been detected at up to 415 mg/L (ppm) in groundwater 

in the vicinity of an airport (Sills and Blakeslee 1992). No information on the background levels of 

ethylene glycol in soil, surface water, or groundwater was located. Additional information regarding the 

levels of ethylene glycol in ambient air, drinking water, surface water, groundwater, and soil is needed. 

Some older data on ethylene glycol levels in foods, particularly those stored in cellulose films or in PET 

bottles are available (Castle et al. 1988a; Kashtock and Breder 1980). Additional quantitative information 

on current levels of ethylene glycol in various environmental media and levels of contamination in foods 

would be helpful in assessing the health risks to the general population and in occupational settings. 

Exposure Levels in Humans. Little quantitative information on ethylene glycol levels in various 

human tissues and body fluids of a control population, populations near hazardous waste sites, or 

occupationally exposed groups in the United States is available. Most information is available for oral 

exposures derived from intentional or accidental poisonings (Gabow et al. 1986; Hewlett et al. 1986; 

Jacobsen et al. 1988; Parry and Wallach 1974; Robinson and McCoy 1989; Vale 1979; Wiener and 

Richardson 1988). Some information is available on plasma glycolate levels for poisoning victims 

admitted to a hospital (Jacobsen et al. (1984), and on urine and other tissues (Cheng et al. 1987; Rothman 

et al. 1986; Winek et al. 1978). Data are needed on the levels of ethylene glycol and its metabolites in 
 

 

 

 

ETHYLENE GLYCOL 205 

6. POTENTIAL FOR HUMAN EXPOSURE 

body tissues and fluids especially from dermal and inhalation studies. Two studies have been located that 

report urinary concentrations for airport de-icing workers and car mechanics (Gérin et al. 1997; Laitinen 

et al. 1995). Additional information on control populations, populations living in the vicinity of 

hazardous waste sites, and those who are occupationally exposed to ethylene glycol is needed. 

This information is necessary for assessing the need to conduct health studies on these populations. 

Exposures of Children. Information regarding the background exposure of children to ethylene 

glycol is not available. Body burden studies measuring the levels of ethylene glycol in the blood, urine, 

and body tissue of children would be helpful. Studies measuring the levels of this chemical in the 

neonatal blood, cord blood, and meconium fluid of infants would also be helpful. Levels of ethylene 

glycol in breastmilk have not been located. Children are considered to be more susceptible to accidental 

ingestion of ethylene glycol than adults (Leth and Gregersen 2005). Information is needed regarding how 

effective the use of a bittering agent has been in deterring accidental ingestion of ethylene glycol by 

children. 

Child health data needs relating to susceptibility are discussed in Section 3.12.2, Identification of Data 

Needs: Children’s Susceptibility. 

Exposure Registries. No exposure registries for ethylene glycol were located. This substance is not 

currently one of the compounds for which a sub-registry has been established in the National Exposure 

Registry. The substance will be considered in the future when chemical selection is made for subregistries to be established. The information that is amassed in the National Exposure Registry facilitates 

the epidemiological research needed to assess adverse health outcomes that may be related to exposure to 

this substance. 

6.8.2 Ongoing Studies 

Ongoing studies related to the potential for human exposure to ethylene glycol were not located. 
ETHYLENE GLYCOL 206 

6. POTENTIAL FOR HUMAN EXPOSURE 

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ETHYLENE GLYCOL 207 

7. ANALYTICAL METHODS 

The purpose of this chapter is to describe the analytical methods that are available for detecting, 

measuring, and/or monitoring ethylene glycol, its metabolites, and other biomarkers of exposure and 

effect to ethylene glycol. The intent is not to provide an exhaustive list of analytical methods. Rather, the 

intention is to identify well-established methods that are used as the standard methods of analysis. Many 

of the analytical methods used for environmental samples are the methods approved by federal agencies 

and organizations such as EPA and the National Institute for Occupational Safety and Health (NIOSH). 

Other methods presented in this chapter are those that are approved by groups such as the Association of 

Official Analytical Chemists (AOAC) and the American Public Health Association (APHA). 

Additionally, analytical methods are included that modify previously used methods to obtain lower 

detection limits and/or to improve accuracy and precision. 

7.1 BIOLOGICAL MATERIALS 

Table 7-1 is a summary of some of the most commonly used methods reported in the literature for 

detecting ethylene glycol in biological samples. The primary method for measuring ethylene glycol in 

biological samples is derivatization followed by gas chromatography (GC) using either a flame ionization 

detector (FID) or mass spectrometry (MS) for quantification. GC is the preferred analytical method 

because of the ease of sample preparation and the accuracy of the quantification of sample concentrations. 

Alkali flame ionization detectors have also been used for ethylene glycol analysis and give a response 

ratio of 3:1 compared with FID (Bogusz et al. 1986). 

Sample preparation for GC is important and proceeds through several steps: acidification, esterification, 

and extraction into an organic solvent. The use of internal standards is necessary for quantification. 

Detection of ethylene glycol in biological samples using GC with either FID or MS is very sensitive, with 

detection limits ranging from sub to low ppm. The coefficient of variation (CV) varies with the 

concentration of glycol used but typically ranges from 0.4 to 27% and is usually <10%. In GC 

procedures, the glycols and their acid metabolites are derivatized to form esters in order to facilitate 

quantitative elution from the chromatographic columns (see Table 7-1). Yao and Porter (1996) and Porter 

et al. (1999) have developed a procedure for the simultaneous determination of ethylene glycol and 

glycolic acid in human serum. The entire procedure can be completed in <2 hours. Simple and rapid 

methods are also available for the quantitation of the glycols in urine, serum, or deproteinated whole 
 

 

 

 

 

 

 

ETHYLENE GLYCOL 208 

7. ANALYTICAL METHODS 

Table 7-1. Analytical Methods for Determining Ethylene Glycol in 

Biological Materials
 

Sample 

Analytical detection Percent 

Sample matrix Preparation method method limit recovery Reference 

Human plasma Deproteinization with acetic HRGC/MS 5 ppm 94–106 Giachetti et 

acid; vortex; centrifugation; al. 1989 

supernatant spiked with 

internal standard; reaction 

with butyl-boronic acid; 

neutralize with NH4OH, 

extraction with 

dichloromethane; 

concentration. 

Human serum Internal standard (in HRGC/FID NR 95 Smith 1984 

acetonitrile) added to sample; 

centrifugation to remove 

protein precipitate; 

esterification with 

butylboronic acid and 

2,2-dimethoxypropane; 

neutralization with NH4OH in 

acetonitrile. 

Human serum Addition of internal standard GC/MS 10 ppm 91.1% Porter et al. 

(ethylene glycol (in acetonitrile) followed by (ethylene 1999 

and glycolic centrifugation. Supernate is glycol); 

acid) treated with 2,2-dimethoxy­ 77.6% 

propane/dimethylformamide. (glycolic 

Volume is then reduced, but acid) 

not to dryness. 

Human serum Deprotonization of samples CCGC 10 ppm NR Williams et 

via ultrafiltration followed by al. 2000 

addition of internal standard 

to the filtrate and injection into 

the GC. 

Human serum Internal standard added; HRGC/FID 1.0 ppm 89–98 Houzé et al. 

and urine centrifugation; derivatization 1993 

with phenylboronate in 

methanol. 

Human Anhydrous Na2SO4 ground GC/FID/AFID NR 70 Bogusz et 

blood/tissue with sample; derivatization al. 1986 

with n-butylboronic acid in 

acetone containing internal 

standard; centrifugation or 

filtration. 
 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 209 

7. ANALYTICAL METHODS 

Table 7-1. Analytical Methods for Determining Ethylene Glycol in 

Biological Materials
 

Sample 

Analytical detection Percent 

Sample matrix Preparation method method limit recovery Reference 

Human serum Colorimetric: precipitation of Absorbance at 1.0 mmol/L NR Fraser and 

(glycolic acid) protein with trichloroacetic 580 nm or (60 ppm, MacNeil 

acid followed by GC/FID as w/v) for both 1993 

centrifugation, addition of appropriate methods; 3– 

chromotropic acid, heating, 6% RSD 

and dilution; gas 

chromatographic: addition of 

internal standard and acetone 

followed by centrifugation, 

addition of NaOH, 

evaporation to dryness, and 

formation of methyl ester. 

Humans serum Extraction from salted, HPLC/UV 0.05 mmol/L NR Hewlett et 

(glycolic acid) acidified serum using methyl (3 ppm, al. 1986 

ethyl ketone followed by w/v); 1% 

removal of organic phase and RSD 

evaporation to dryness and 

derivatization with PNBDI. 

Urine Acidification; extraction with TLC NR NR Riley et al. 

CHCl3; concentration; TLC. 1982 

Urine (sodium Untreated samples read in Fluorescence NR NR Winter et al. 

fluorescein) borosilicate tubes. (Wood's lamps) 1990 

Dog urine Dilution; NaCl addition and HPLC/UV 1–2 ng 96 Hewlett et 

(glycolic acid) acidification; extraction in al. 1983 

MEK; evaporation; dissolution 

of residue in ethylacetate; 

derivatization with PNBDl. 

Human plasma, Heparinized blood HPLC/UV Plasma: 85 Brega et al. 

urine (oxalate) deproteinated by addition of 0.15 mg/L 1992 

acetonitrile and phosphate (ppm, w/v); 

buffer (pH=7), centrifugation, 7.5% RSD; 

removal of solvent and urine: 

evaporation to dryness; 0.5 mg/L 

derivatization as for urine; (ppm, w/v); 

urine acidified and derivatized 5% RSD. 

using 1,2-diaminobenzene, 

adjustment of pH to 5–6, 

centrifugation. 

Kidney tissue Tissue ground with acidic TLC NR NR Riley et al. 

dog (hippurate) methanol; filtration; 1982 

concentration; spot on 

254 nm TLC plate. 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 210 

7. ANALYTICAL METHODS 

Table 7-1. Analytical Methods for Determining Ethylene Glycol in 

Biological Materials
 

Sample 

Analytical detection Percent 

Sample matrix Preparation method method limit recovery Reference 

Human tissue	 Samples extraction in HPLC HPLC/RI 5 ppm 98 at Wu and 

grade water for 24 hours; 1 mg/mL Malinin 1987 

filtration of supernatant. (1,000 ppm) 

AFID = alkali flame ionization detector; ATP = adenosine triphosphate; CHCl3 = chloroform; CH3OH = methanol; 

CCGC = Capillary column gas chromatography; ECD = electron capture detector; EG = ethylene glycol; FID = flame 

ionization detector; GC = gas chromatography; HCl = hydrochloric acid; HClO4 = chloroform; HPLC = highperformance liquid chromatography; HRGC = high resolution gas chromatography; KOH = potassium hydroxide; 

MEK = methylethyl ketone; MgSO4 = magnesium sulfate; MS = mass spectrometry; NaCl = sodium chloride; 

NAD = nicotinamide adenine dinucleotide; Na2SO4 = sodium sulfate; NH4OH = ammonium hydroxide; NR = not 

reported; PG = propylene glycol; PNBDl = O-p-nitrobenzyl-N,N'-diisopropylisourea; RSD = relative standard 

deviation; RI = refractive index detector; TLC = thin-layer chromatography; UV = ultraviolet detector; 

w/v = weight:volume 
 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 211 

7. ANALYTICAL METHODS 

blood. These methods use direct sample injection without prior solvent extraction and derivatization 

(Aarstad et al. 1993; Edinboro et al. 1993; Jonsson et al. 1989). However, such methods, particularly 

those that use packed columns may misidentify propionic acid (found in patients with methylmalonic 

acidemia) as ethylene glycol (Shoemaker et al. 1992). 

High performance liquid chromatography (HPLC) has also been used to identify ethylene glycol and its 

metabolites such as glycolate (Hewlett et al. 1983, 1986), hippurate (Riley et al. 1982), and oxalate 

(Brega et al. 1992) in biological samples, particularly blood and urine. Positive results may be confirmed 

with GC/MS. This makes GC/MS the preferred method since the HPLC step can be omitted. However, 

HPLC methods to measure plasma levels of glycolate have been used to aid in diagnosis and treatment of 

ethylene glycol poisoning (Hewlett et al. 1986; Jacobsen et al. 1988). Gas chromatographic and 

colorimetric methods for quantification of glycolate have been presented (Fraser and MacNeil 1993). 

Microscopy can be used to identify metabolic products of ethylene glycol. Scanning electron microscopy 

(SEM) at 20 kilovolts will detect crystals of calcite, calcium oxalate monohydrate, and calcium oxalate 

dihydrate in kidney tissue (Siew et al. 1975b). Phase-contrast polarization and light microscopy X-ray 

powder diffraction may be used to identify hippuric acid crystals in urine (Foit et al. 1985). 

The use of ethylene oxide to sterilize tissue for transplantation may result in the formation of ethylene 

glycol when ethylene oxide is in prolonged contact with tissue. To quantify the formation of ethylene 

glycol in tissue, an HPLC method using a differential refractive index detector has been developed. The 

HPLC system can be used to detect ppm levels of ethylene glycol with a sensitivity of 2x10-6 refractive 

index unit full scale. This procedure has three advantages: (1) requires only 4 minutes for analysis, 

(2) simple sample preparation, and (3) good reproducibility (Wu and Malinin 1987). 

Techniques using GC and various detection systems to detect and quantify ethylene glycol in human 

blood have been developed for use in hospital laboratories to assist in the diagnosis of ethylene glycol 

poisoning (caused by drinking antifreeze containing ethylene glycol). These techniques are quite rapid, 

usually <30 minutes, and do not require elaborate sample preparation. The specific techniques used for 

each analytical method are listed in the table if that information was provided by the author(s). 

An alternative method, developed in a hospital, for detecting ethylene glycol in blood is the use of the 

DuPont Automated Clinical Analyzer triglyceride assay pack. This enzymatic method, while relatively 

simple, cannot be used when the triglyceride concentration of the serum exceeds 12 g/L and requires that 
 

 

 

 

 

 

ETHYLENE GLYCOL 212 

7. ANALYTICAL METHODS 

positive results for ethylene glycol be confirmed using another method (Ochs et al. 1988; Ryder et al. 

1986). The enzymatic method has been modified to eliminate some of the interference problems present 

in the earlier methods (Blandford and Desjardins 1994). 

Thin-layer chromatography (TLC) with a chloroform solvent has been used to detect ethylene glycol and 

its metabolites in urine or renal tissue (Riley et al. 1982). Metabolites of ethylene glycol in the blood may 

be detected by analytical isotachophoresis using a system equipped with both a conductivity detector and 

an ultraviolet detector. Blood and serum samples should not have been previously treated with oxalate, 

citrate, or ethylene diamine tetracetic acid. This technique may be of value when ethylene glycol 

poisoning is suspected but sufficient time has elapsed for metabolism of the compound to have occurred 

(Ovrebo et al. 1987). A simple and rapid colorimetric method that uses chromatropic acid has been 

proposed for the quantitation of glycolic acid, the major toxic metabolite of ethylene glycol (Fraser and 

MacNeil 1993). 

No information was located on detecting ethylene glycol in feces, adipose tissue, or human milk. 

7.2 ENVIRONMENTAL SAMPLES 

As with biological samples, GC is the major technique used to determine ethylene glycol concentrations 

in environmental samples whether in air, water, food, drugs, or other substances. Capillary gas 

chromatography with FID or ECD, possibly followed by MS, generally gives good quantitative results 

down to the ppm range with recovery usually >80%. The determination of ethylene glycol in air requires 

adsorption onto a surface and subsequent extraction. Water samples may be analyzed without preparation 

(EPA 1995a, 1995b). Detection of ethylene glycol in foods and drugs may be accomplished by 

chromatography of the sample; for substances with a high fat content, extraction with hexane may be used 

to remove the fat. Table 7-2 is a summary of some of the most commonly used methods reported in the 

literature for detecting ethylene glycol in environmental samples. The specific techniques used for each 

analytical method are listed in the table if that information was provided by the author(s). 

Air sampling for ethylene glycol is performed by adsorption onto a resin column such as Amberlite 

XAD-2. Although activated charcoal filters have some utility, recovery is greater with the Amberlite, and 

it is the preferred adsorption medium. Ethylene glycol is then solvent-extracted with recovery of 98%. If 

activated charcoal is used for adsorption, 5% methanol in dichloromethane is the best solvent with 

maximum recovery of 84% (Andersson et al. 1982, 1984). An alternative method for sampling ethylene 
 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 213 

7. ANALYTICAL METHODS 

Table 7-2. Analytical Methods for Determining Ethylene Glycol in 

Environmental Samples
 

Sample Analytical Sample Percent 

matrix Preparation method method detection limit recovery Reference 

Air Sample collection on GC/FID 0.05 ppm 93.4–101 NIOSH 1996 

glass fiber filters and silica 

gel; extraction with 

methanol; ultrasonic bath 

(Method 5523). 

Air Sample adsorbed on 

Amberlite® XAD-2 with 

GC/FID NR 75–98 Andersson et al. 1982 

personal sampling pump; 

extraction with diethyl 

ether. 

Water Direct injection (Method GC/FID NR NR EPA 2000 

8015C). 

Water Direct injection (Method GC/FTIR NR NR EPA 1996 

8430). 

Plastics Sample extraction from GC/FID 16.5 ng 58–61 Muzeni 1985 

plastic with carbon 

disulfide. 

Plastics Sample extraction with GC/FID 2 ppm NR De Rudder et al. 

solvent of ethylacetate­ 1986 

water-methanol. 

Ground Extraction with anhydrous GC/FID NR NR AOAC 1990b 

tobacco methanol. 

Aqueous Sample concentration, GC/FID 50 ppb 97–103 Kashtock and Breder 

solution then dilution with water; 1980 

concentration with helium 

gas; redilution. 

Beer Addition of ammonium HRGC/FID 0.73 ppm 88 Williamson and 

sulfate and extract with Iverson 1993 

ethyl acetate. 

Food Addition of hot water to HRGC/FID; 10 ppm 78–107 Castle et al. 1988b 

sample to obtain slurry; GC/MS 

extraction with hexane; 

precipitation of sugars 

with calcium hydroxide; 

concentration; 

derivatization with BSTFA. 

Anchovies Extraction with methanol HRGC/MS/ 12.5 ppb NR Matusik et al. 1993 

and concentration. MS (PICI) 

BSTFA = bis(trimethylsilyl)trifluoroacetamide; FID = flame ionization; GC = gas chromatography; HRGC = high 

resolution gas chromatography; MS = mass spectrometry; MS/MS = tandem mass spectrometry; PICI = positive ion 

chemical ionization 
 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 214 

7. ANALYTICAL METHODS 

glycol involves passage of air through a glass fiber filter with a silica gel tube. Ethylene glycol is then 

extracted in a 2-propanol:water solvent mixture and injected into the gas chromatograph (Tucker and 

Deye 1981). A similar version of this method is the NIOSH-approved method for the determination of 

ethylene glycol in occupational air (see Table 7-2). 

A portable, automated, photoionization gas chromatograph has been used to detect ethylene glycol in air 

samples in industrial facilities at levels as low as 0.05 ppm (Adams and Collins 1988). 

Ethylene glycol may be detected by a colorimetric reaction with 3-methyl-2-benzothiazolinone hydrazone 

hydrochloride after oxidation of the glycols to the corresponding aldehydes with acidified permanganate. 

The solution is read at 630 nm in a spectrophotometer. This method may be used for ethylene glycol in 

water (Evans and Dennis 1973) or to detect ethylene oxide in air (Kring et al. 1984); however, this 

method is not quantitative and is relatively insensitive compared with GC/MS. 

The migration of ethylene glycol from plastics into solution can be studied with GC. Sample preparation 

methods include extraction in hydrochloric acid (Ball 1984), distilled water (Spitz and Weinberger 1971), 

carbon disulfide (Muzeni 1985), dimethylformamide (Danielson et al. 1990), and a mixture of ethyl 

acetate, water, and methanol (De Rudder et al. 1986). Other methods for detecting ethylene glycol in 

industrial products include HPLC (Aboul-Enein and Islam 1989) and a periodate flow-through ionselective electrode (Diamandis et al. 1980). 

The presence of ethylene glycol in foods packaged with plastic films containing the compounds has been 

studied, as have ethylene glycol levels in drugs sterilized with ethylene oxide. Sample preparation is 

important because procedures vary depending on the fat content of the food sample. Foods with low fat 

content can be extracted with ethyl acetate, derivatized to a trimethylsilyl ether, and then injected into the 

gas chromatograph. For foods with a high fat content, hexane is used as the defatting agent prior to 

derivatization. Quantifying ethylene glycol in wines requires no preparation of the samples prior to 

analysis (Kaiser and Rieder 1987; Klaus and Fischer 1987). Drugs in aqueous solutions may be analyzed 

directly, water insoluble drugs should be extracted in water, and ointments may be dissolved in hexane 

and then extracted with water. Recovery is between 80 and 114%, with detection limits in the low-ppm 

range (Hartman and Bowman 1977; Manius 1979). Although the use of TLC (Ballarin 1980) has been 

recommended, it has been superseded by GC. 

No information was located on techniques for detecting and analyzing ethylene glycol in soil. 
 

 

 

 

 

 

 

ETHYLENE GLYCOL 215 

7. ANALYTICAL METHODS 

7.3 ADEQUACY OF THE DATABASE 

Section 104(i)(5) of CERCLA, as amended, directs the Administrator of ATSDR (in consultation with the 

Administrator of EPA and agencies and programs of the Public Health Service) to assess whether 

adequate information on the health effects of ethylene glycol is available. Where adequate information is 

not available, ATSDR, in conjunction with NTP, is required to assure the initiation of a program of 

research designed to determine the health effects (and techniques for developing methods to determine 

such health effects) of ethylene glycol. 

The following categories of possible data needs have been identified by a joint team of scientists from 

ATSDR, NTP, and EPA. They are defined as substance-specific informational needs that if met would 

reduce the uncertainties of human health assessment. This definition should not be interpreted to mean 

that all data needs discussed in this section must be filled. In the future, the identified data needs will be 

evaluated and prioritized, and a substance-specific research agenda will be proposed. 

7.3.1 Identification of Data Needs 

Methods for Determining Biomarkers of Exposure and Effect. 

Exposure. Methods are available for the determination of ethylene glycol in blood, tissue, and urine 

(Bogusz et al. 1986; Giachetti et al. 1989; Houzé et al. 1993; Riley et al. 1982; Smith 1984; Wu and 

Malinin 1987) with sensitivities in the low and sub-ppm range. Methods are also available for 

metabolites of ethylene glycol (glycolic acid, oxalic acid) in blood and urine (Brega et al. 1992; Fraser 

and MacNeil 1993; Hewlett et al. 1986) with sensitivities as low as 3 ppm for glycolic acid and of 

0.15 ppm for oxalic acid. Glycolic acid was identified in Chapter 3 as a sensitive biomarker of exposure 

to ethylene glycol. These methods seem to be adequate for the measurement of ethylene glycol and its 

metabolites in the human population. 

Effect. Serum concentrations of blood urea nitrogen (BUN) or creatinine can serve as indicators of renal 

toxicity induced by exposure to ethylene glycol, but these are not specific for ethylene glycol intoxication 

(Grauer et al. 1987). 

Methods for Determining Parent Compounds and Degradation Products in Environmental 

Media. Methods for the determination of ethylene glycol have been reported for air (Andersson et al. 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 216 

7. ANALYTICAL METHODS 

1982; NIOSH 1996), water or aqueous solutions (EPA 1996, 2000; Kashtock and Breder 1980), and 

foods (Castle et al. 1988b; Matusik et al. 1993; Williamson and Iverson 1993). Methods have also been 

developed for the determination of glycols that leach from plastics (De Rudder et al. 1986; Muzeni 1985) 

and can end up in foods stored in containers made from the plastics. 

The MRL for inhalation exposure to ethylene glycol is 0.5 ppm and thus requires a method level of 

detection (LOD) of 0.5 ppm. This value is below the LODs of the methods reported. Although it should 

be possible to increase the sampling volumes and increase the sensitivities of the methods, this would 

need to be shown to be free of problems. Oral MRLs have been established to be 2 mg/kg/day for acute 

exposure and 0.2 mg/kg/day for chronic exposure. Assuming a 70-kg individual and oral intakes of either 

2 L/day of water or 2 kg/day of food, analytical methods would need sensitivities <70 ppm in water or 

food. The methods reported for aqueous solutions (LOD=50 ppb, Kashtock and Breder 1980), beer 

(LOD=0.73 ppm, Williamson and Iverson 1993), and foods (LOD=10 ppm, Castle et al. 1988b; 

LOD=12.5 ppb, Matusik et al. 1993) should be adequate to measure acute exposure. However, chronic 

exposure requires method LODs of approximately 7 ppm and only the methods of Kashtock and Breder 

(1980) for aqueous solutions, Williamson and Iverson (1993) for beer, and Matuslik et al. (1993) for 

anchovies can meet this requirement. The applicability of these methods to other beverages and foods has 

not been demonstrated. Thus, additional methods should be developed and validated for ethylene glycol 

in other beverages and foods at concentrations relevant to the chronic oral MRL. 

7.3.2 Ongoing Studies 

Ongoing studies related to the potential for human exposure to ethylene glycol were not located. 
ETHYLENE GLYCOL 217 

8. REGULATIONS, ADVISORIES, AND GUIDELINES 

MRLs are substance specific estimates, which are intended to serve as screening levels, are used by 

ATSDR health assessors and other responders to identify contaminants and potential health effects that 

may be of concern at hazardous waste sites. 

An MRL of 2 mg/m3

 has been derived for acute-duration inhalation exposure (≤14 days) to ethylene 

glycol. The MRL is based on a NOAEL of 23 mg/m3

 for respiratory tract irritation and systemic toxicity 

in humans (Wills et al. 1974), which was divided by an uncertainty factor of 10 (for human variability). 

An MRL of 0.8 mg/kg/day has been derived for acute-duration oral exposure (14 days or less) to ethylene 

glycol. BMD dose modeling was conducted using developmental toxicity data in mice (total 

malformations and a skeletal variation) (Neeper-Bradley et al. 1995; Tyl 1989). The resulting BMDL10 of 

76 mg/kg/day was divided by an uncertainty factor of 100 (10 for extrapolation from animals to humans 

and 10 for human variability) to derive an MRL of 0.8 mg/kg/day for acute-duration oral exposure to 

ethylene glycol. 

The acute-duration oral MRL of 0.8 mg/kg/day has been adopted for intermediate-duration oral exposure 

(15–364 days) to ethylene glycol. The critical effect for intermediate-duration exposure is kidney lesions 

in male Wistar rats (Cruzan et al. 2004). Basing the intermediate-duration MRL on the NOAEL for this 

effect yielded a value that is higher than the acute-duration MRL. Because available evidence indicates 

that the acute-duration MRL should be protective for kidney effects following longer-term exposure, the 

acute-duration value of 0.8 mg/kg/day was adopted for intermediate-duration exposure. 

EPA (IRIS 2010) assigned ethylene glycol an oral reference dose (RfD) of 2 mg/kg/day with an 

uncertainty factor of 100 (10 for interspecies extrapolation and 10 for differences in individual human 

sensitivity) based on kidney toxicity in rats (DePass et al. 1986a). 

EPA has not derived an inhalation reference concentration (RfC) for ethylene glycol. 

Neither the International Agency for Research on Cancer (IARC) nor the EPA has classified ethylene 

glycol for human carcinogenicity (IARC 2006; IRIS 2010). The American Conference of Governmental 

Industrial Hygienists (ACGIH) has classified ethylene glycol as an A4 carcinogen (not classifiable as a 

human carcinogen) (ACGIH 2006). The National Toxicology Program (NTP) has not classified ethylene 
ETHYLENE GLYCOL 218 

8. REGULATIONS, ADVISORIES, AND GUIDELINES 

glycol for human carcinogenicity, but it appears on the Testing Status of Agents at NTP and has 

undergone standard toxicology, carcinogenesis, reproductive, developmental, and genetic toxicity studies 

(NTP 2007). 

OSHA (2006) and NIOSH (2005) have not established a permissible exposure limit (PEL) or a 

recommended exposure limit (REL) for ethylene glycol. Under the “Proposed Rule on Air 

Contaminants" (29 CFR 1910, Docket No. H-020), NIOSH questioned whether the OSHA PEL for 

ethylene glycol (ceiling 50 ppm) was adequate to protect workers from potential health hazards (NIOSH 

2005). ACGIH (2006) has established a 100 mg/m3

 ceiling limit for ethylene glycol. 

EPA (2007b) has designated ethylene glycol as a hazardous air pollutant (HAP) under the Clean Air Act 

(CAA). Ethylene glycol is on the list of chemicals appearing in “Toxic Chemicals Subject to Section 313 

of the Emergency Planning and Community Right-to-Know Act of 1986" and has been assigned a 

reportable quantity (RQ) limit of 5,000 pounds (EPA 2007d). The RQ represents the amount of a 

designated hazardous substance which, when released to the environment, must be reported to the 

appropriate authority. 

Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), ethylene glycol is exempt from 

tolerances for residues when used in foliar applications to peanut plants (EPA 2007f). 

The international and national regulations, advisories, and guidelines regarding ethylene glycol in air, 

water, and other media are summarized in Table 8-1. 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 219 

8. REGULATIONS, ADVISORIES, AND GUIDELINES 

Table 8-1. Regulations, Advisories, and Guidelines Applicable to Ethylene Glycol 

Agency Description Information Reference 

INTERNATIONAL 

Guidelines: 

IARC Carcinogenicity classification No data IARC 2006 

WHO Air quality guidelines 

Drinking water quality guidelines 

No data 

No data 

WHO 2000 

WHO 2004 

NATIONAL 

Regulations and 

Guidelines: 

a. Air 

ACGIH 

EPA 

TLV (8-hour TWA) 

TLV-ceiling (aerosol only) 

The Second List of AEGL priority 

chemicals for guideline developmenta 

Hazardous air pollutant 

No data 

100 mg/m3 

Yes 

Yes 

ACGIH 2006 

EPA 2007a 

EPA 2007b 

42 USC 7412 

NIOSH REL (10-hour TWA) Not establishedb NIOSH 2005 

IDLH No data 

OSHA PEL (8-hour TWA) for general industry No data OSHA 2006 

29 CFR 1910.1000 

b. Water 

EPA Drinking water standards and health 

advisories 

EPA 2006b 

1-Day health advisory for a 10-kg 

child 

20 mg/L 

10-Day health advisory for a 10-kg 

child 

6 mg/L 

DWEL 

Lifetime 

10-4 Cancer risk 

70 mg/L 

14 mg/L 

No data 

National primary drinking water 

standards 

No data EPA 2003 

c. Food 

EPA Inert ingredients in pesticide products List 3c EPA 2004a 

FDA 

Exempt from the requirement of a 

tolerance 

Substance for use only as components 

of adhesives 

When used in foliar 

applications to peanut 

plants 

Yes 

EPA 2007f 

40 CFR 180.1040 

FDA 2006 

21 CFR 175 

d. Other 

ACGIH Carcinogenicity classification A4d ACGIH 2006 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 220 

8. REGULATIONS, ADVISORIES, AND GUIDELINES 

Table 8-1. Regulations, Advisories, and Guidelines Applicable to Ethylene Glycol 

Agency Description Information Reference 

NATIONAL (cont.) 

CPSC Designated a hazardous substance Ethylene glycol and CPSC 2007 

under Section 3(b) of the Federal mixtures containing 

Hazardous Substances Act and 

requires special labeling 

10% or more by weight 

of ethylene glycole 

EPA Carcinogenicity classification No data IRIS 2010 

RfC No data 

RfD 2 mg/kg/day 

Master Testing List Yesf EPA 2007c 

Superfund, emergency planning, and 

community right-to-know 

Designated CERCLA hazardous Yesg EPA 2007d 

substance 40 CFR 302.4 

Reportable quantity 5,000 pounds 

Effective date of toxic chemical 01/01/87 EPA 2007e 

release reporting 40 CFR 372.65 

NTP Carcinogenicity classification No datah NTP 2005 

a

The Second List of AEGL priority chemicals is a composite of 371 priority chemicals from numerous priority lists of
 

acutely toxic chemicals and represents the selection of chemicals for AEGL development by the NAC/AEGL (EPA
 

2007a).

b

NIOSH has not established a REL for ethylene glycol under the “Proposed Rule on Air Contaminants" (29 CFR
 

1910, Docket No. H-020) in which NIOSH questioned whether the OSHA PEL for ethylene glycol (ceiling 50 ppm)
 

was adequate enough to protect workers from potential health hazards (NIOSH 2005).
 c

List 3: Inerts of unknown toxicity are placed on this list if there was no basis for listing it on any of the other lists.
 

EPA continues to evaluate ethylene glycol as additional information becomes available, to determine if
 

reclassification to List 1, 2, or 4 is appropriate (EPA 2004a).

d

A4: not classifiable as a human carcinogen
 e

Ethylene glycol requires special labeling with the word “warning”' and the statement “harmful or fatal if swallowed”
 

because ethylene glycol and mixtures containing 10% or more by weight of ethylene glycol are commonly marketed,
 

stored, and used in a manner that increases the possibility of accidental ingestion (CPSC 2007).

f

Ethylene glycol was recommended to the MTL by the U.S. EPA’s Office of Air and Radiation on the basis that it is a 

hazardous air pollutant. Ethylene glycol was added to the MTL in 1995 and EPA is initiating development of a testing 

action via TSCA Section 4 FRM, a TSCA Section 4 ECA, or a VTA (EPA 2007c). The testing needs indicated for
 

health effects include acute, subchronic toxicity/90 day, neurotoxicity, and immunotoxicity studies.
 g

Designated CERCLA hazardous substance pursuant to Section 112 of the Clean Air Act.

h

Ethylene glycol has undergone the following testing at NTP: toxicology, carcinogenesis, reproductive,
 

developmental, and genetic toxicity studies (NTP 2007).
 

ACGIH = American Conference of Governmental Industrial Hygienists; AEGL = acute exposure guideline levels;
 

CERCLA = Comprehensive Environmental Response, Compensation, and Liability Act; CFR = Code of Federal
 

Regulations; CPSC = Consumer Product Safety Commission; DWEL = drinking water equivalent level;
 

ECA = Enforceable Consent Agreement; EPA = Environmental Protection Agency; FDA = Food and Drug
 

Administration; FRM = Final Rule-Making; IARC = International Agency for Research on Cancer; IDLH = immediately
 

dangerous to life or health; IRIS = Integrated Risk Information System; MTL = Master Testing List; NIOSH = National
 

Institute for Occupational Safety and Health; NTP = National Toxicology Program; OSHA = Occupational Safety and 

Health Administration; PEL = permissible exposure limit; REL = recommended exposure limit; RfC = inhalation
 

reference concentration; RfD = oral reference dose; STEL = short-term expoure limit; TLV = threshold limit values;
 

TSCA = Toxic Substances Control Act; TWA = time-weighted average; USC = United States Code; VTA = Voluntary
 

Testing Agreement; WHO = World Health Organization
 
 

 

 

 

 

 

 

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ETHYLENE GLYCOL 249 

10. GLOSSARY 

Absorption—The taking up of liquids by solids, or of gases by solids or liquids. 

Acute Exposure—Exposure to a chemical for a duration of 14 days or less, as specified in the 

Toxicological Profiles. 

Adsorption—The adhesion in an extremely thin layer of molecules (as of gases, solutes, or liquids) to the 

surfaces of solid bodies or liquids with which they are in contact. 

Adsorption Coefficient (Koc)—The ratio of the amount of a chemical adsorbed per unit weight of 

organic carbon in the soil or sediment to the concentration of the chemical in solution at equilibrium. 

Adsorption Ratio (Kd)—The amount of a chemical adsorbed by sediment or soil (i.e., the solid phase) 

divided by the amount of chemical in the solution phase, which is in equilibrium with the solid phase, at a 

fixed solid/solution ratio. It is generally expressed in micrograms of chemical sorbed per gram of soil or 

sediment. 

Benchmark Dose (BMD)—Usually defined as the lower confidence limit on the dose that produces a 

specified magnitude of changes in a specified adverse response. For example, a BMD10 would be the 

dose at the 95% lower confidence limit on a 10% response, and the benchmark response (BMR) would be 

10%. The BMD is determined by modeling the dose response curve in the region of the dose response 

relationship where biologically observable data are feasible. 

Benchmark Dose Model—A statistical dose-response model applied to either experimental toxicological 

or epidemiological data to calculate a BMD. 

Bioconcentration Factor (BCF)—The quotient of the concentration of a chemical in aquatic organisms 

at a specific time or during a discrete time period of exposure divided by the concentration in the 

surrounding water at the same time or during the same period. 

Biomarkers—Broadly defined as indicators signaling events in biologic systems or samples. They have 

been classified as markers of exposure, markers of effect, and markers of susceptibility. 

Cancer Effect Level (CEL)—The lowest dose of chemical in a study, or group of studies, that produces 

significant increases in the incidence of cancer (or tumors) between the exposed population and its 

appropriate control. 

Carcinogen—A chemical capable of inducing cancer. 

Case-Control Study—A type of epidemiological study that examines the relationship between a 

particular outcome (disease or condition) and a variety of potential causative agents (such as toxic 

chemicals). In a case-controlled study, a group of people with a specified and well-defined outcome is 

identified and compared to a similar group of people without outcome. 

Case Report—Describes a single individual with a particular disease or exposure. These may suggest 

some potential topics for scientific research, but are not actual research studies. 

Case Series—Describes the experience of a small number of individuals with the same disease or 

exposure. These may suggest potential topics for scientific research, but are not actual research studies. 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 250 

10. GLOSSARY 

Ceiling Value—A concentration of a substance that should not be exceeded, even instantaneously. 

Chronic Exposure—Exposure to a chemical for 365 days or more, as specified in the Toxicological 

Profiles. 

Cohort Study—A type of epidemiological study of a specific group or groups of people who have had a 

common insult (e.g., exposure to an agent suspected of causing disease or a common disease) and are 

followed forward from exposure to outcome. At least one exposed group is compared to one unexposed 

group. 

Cross-sectional Study—A type of epidemiological study of a group or groups of people that examines 

the relationship between exposure and outcome to a chemical or to chemicals at one point in time. 

Data Needs—Substance-specific informational needs that if met would reduce the uncertainties of human 

health assessment. 

Developmental Toxicity—The occurrence of adverse effects on the developing organism that may result 

from exposure to a chemical prior to conception (either parent), during prenatal development, or 

postnatally to the time of sexual maturation. Adverse developmental effects may be detected at any point 

in the life span of the organism. 

Dose-Response Relationship—The quantitative relationship between the amount of exposure to a 

toxicant and the incidence of the adverse effects. 

Embryotoxicity and Fetotoxicity—Any toxic effect on the conceptus as a result of prenatal exposure to 

a chemical; the distinguishing feature between the two terms is the stage of development during which the 

insult occurs. The terms, as used here, include malformations and variations, altered growth, and in utero 

death. 

Environmental Protection Agency (EPA) Health Advisory—An estimate of acceptable drinking water 

levels for a chemical substance based on health effects information. A health advisory is not a legally 

enforceable federal standard, but serves as technical guidance to assist federal, state, and local officials. 

Epidemiology—Refers to the investigation of factors that determine the frequency and distribution of 

disease or other health-related conditions within a defined human population during a specified period. 

Genotoxicity—A specific adverse effect on the genome of living cells that, upon the duplication of 

affected cells, can be expressed as a mutagenic, clastogenic, or carcinogenic event because of specific 

alteration of the molecular structure of the genome. 

Half-life—A measure of rate for the time required to eliminate one half of a quantity of a chemical from 

the body or environmental media. 

Immediately Dangerous to Life or Health (IDLH)—The maximum environmental concentration of a 

contaminant from which one could escape within 30 minutes without any escape-impairing symptoms or 

irreversible health effects. 

Immunologic Toxicity—The occurrence of adverse effects on the immune system that may result from 

exposure to environmental agents such as chemicals. 
 

 

 

 

 

 

ETHYLENE GLYCOL 251 

10. GLOSSARY 

Immunological Effects—Functional changes in the immune response. 

Incidence—The ratio of individuals in a population who develop a specified condition to the total 

number of individuals in that population who could have developed that condition in a specified time 

period. 

Intermediate Exposure—Exposure to a chemical for a duration of 15–364 days, as specified in the 

Toxicological Profiles. 

In Vitro—Isolated from the living organism and artificially maintained, as in a test tube. 

In Vivo—Occurring within the living organism. 

Lethal Concentration(LO) (LCLO)—The lowest concentration of a chemical in air that has been reported 

to have caused death in humans or animals. 

Lethal Concentration(50) (LC50)—A calculated concentration of a chemical in air to which exposure for 

a specific length of time is expected to cause death in 50% of a defined experimental animal population. 

Lethal Dose(LO) (LDLo)—The lowest dose of a chemical introduced by a route other than inhalation that 

has been reported to have caused death in humans or animals. 

Lethal Dose(50) (LD50)—The dose of a chemical that has been calculated to cause death in 50% of a 

defined experimental animal population. 

Lethal Time(50) (LT50)—A calculated period of time within which a specific concentration of a chemical 

is expected to cause death in 50% of a defined experimental animal population. 

Lowest-Observed-Adverse-Effect Level (LOAEL)—The lowest exposure level of chemical in a study, 

or group of studies, that produces statistically or biologically significant increases in frequency or severity 

of adverse effects between the exposed population and its appropriate control. 

Lymphoreticular Effects—Represent morphological effects involving lymphatic tissues such as the 

lymph nodes, spleen, and thymus. 

Malformations—Permanent structural changes that may adversely affect survival, development, or 

function. 

Minimal Risk Level (MRL)—An estimate of daily human exposure to a hazardous substance that is 

likely to be without an appreciable risk of adverse noncancer health effects over a specified route and 

duration of exposure. 

Modifying Factor (MF)—A value (greater than zero) that is applied to the derivation of a Minimal Risk 

Level (MRL) to reflect additional concerns about the database that are not covered by the uncertainty 

factors. The default value for a MF is 1. 

Morbidity—State of being diseased; morbidity rate is the incidence or prevalence of disease in a specific 

population. 

Mortality—Death; mortality rate is a measure of the number of deaths in a population during a specified 

interval of time. 
 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 252 

10. GLOSSARY 

Mutagen—A substance that causes mutations. A mutation is a change in the DNA sequence of a cell’s 

DNA. Mutations can lead to birth defects, miscarriages, or cancer. 

Necropsy—The gross examination of the organs and tissues of a dead body to determine the cause of 

death or pathological conditions. 

Neurotoxicity—The occurrence of adverse effects on the nervous system following exposure to a 

chemical. 

No-Observed-Adverse-Effect Level (NOAEL)—The dose of a chemical at which there were no 

statistically or biologically significant increases in frequency or severity of adverse effects seen between 

the exposed population and its appropriate control. Effects may be produced at this dose, but they are not 

considered to be adverse. 

Octanol-Water Partition Coefficient (Kow)—The equilibrium ratio of the concentrations of a chemical 

in n-octanol and water, in dilute solution. 

Odds Ratio (OR)—A means of measuring the association between an exposure (such as toxic substances 

and a disease or condition) that represents the best estimate of relative risk (risk as a ratio of the incidence 

among subjects exposed to a particular risk factor divided by the incidence among subjects who were not 

exposed to the risk factor). An OR of greater than 1 is considered to indicate greater risk of disease in the 

exposed group compared to the unexposed group. 

Organophosphate or Organophosphorus Compound—A phosphorus-containing organic compound 

and especially a pesticide that acts by inhibiting cholinesterase. 

Permissible Exposure Limit (PEL)—An Occupational Safety and Health Administration (OSHA) 

allowable exposure level in workplace air averaged over an 8-hour shift of a 40-hour workweek. 

Pesticide—General classification of chemicals specifically developed and produced for use in the control 

of agricultural and public health pests. 

Pharmacokinetics—The dynamic behavior of a material in the body, used to predict the fate 

(disposition) of an exogenous substance in an organism. Utilizing computational techniques, it provides 

the means of studying the absorption, distribution, metabolism, and excretion of chemicals by the body. 

Pharmacokinetic Model—A set of equations that can be used to describe the time course of a parent 

chemical or metabolite in an animal system. There are two types of pharmacokinetic models: data-based 

and physiologically-based. A data-based model divides the animal system into a series of compartments, 

which, in general, do not represent real, identifiable anatomic regions of the body, whereas the 

physiologically-based model compartments represent real anatomic regions of the body. 

Physiologically Based Pharmacodynamic (PBPD) Model—A type of physiologically based doseresponse model that quantitatively describes the relationship between target tissue dose and toxic end 

points. These models advance the importance of physiologically based models in that they clearly 

describe the biological effect (response) produced by the system following exposure to an exogenous 

substance. 

Physiologically Based Pharmacokinetic (PBPK) Model—Comprised of a series of compartments 

representing organs or tissue groups with realistic weights and blood flows. These models require a 
 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL 253 

10. GLOSSARY 

variety of physiological information: tissue volumes, blood flow rates to tissues, cardiac output, alveolar 

ventilation rates, and possibly membrane permeabilities. The models also utilize biochemical 

information, such as air/blood partition coefficients, and metabolic parameters. PBPK models are also 

called biologically based tissue dosimetry models. 

Prevalence—The number of cases of a disease or condition in a population at one point in time. 

Prospective Study—A type of cohort study in which the pertinent observations are made on events 

occurring after the start of the study. A group is followed over time. 

q1*—The upper-bound estimate of the low-dose slope of the dose-response curve as determined by the 

multistage procedure. The q1* can be used to calculate an estimate of carcinogenic potency, the 

incremental excess cancer risk per unit of exposure (usually μg/L for water, mg/kg/day for food, and 

μg/m3 for air). 

Recommended Exposure Limit (REL)—A National Institute for Occupational Safety and Health 

(NIOSH) time-weighted average (TWA) concentration for up to a 10-hour workday during a 40-hour 

workweek. 

Reference Concentration (RfC)—An estimate (with uncertainty spanning perhaps an order of 

magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups) 

that is likely to be without an appreciable risk of deleterious noncancer health effects during a lifetime. 

The inhalation reference concentration is for continuous inhalation exposures and is appropriately 

expressed in units of mg/m3 or ppm. 

Reference Dose (RfD)—An estimate (with uncertainty spanning perhaps an order of magnitude) of the 

daily exposure of the human population to a potential hazard that is likely to be without risk of deleterious 

effects during a lifetime. The RfD is operationally derived from the no-observed-adverse-effect level 

(NOAEL, from animal and human studies) by a consistent application of uncertainty factors that reflect 

various types of data used to estimate RfDs and an additional modifying factor, which is based on a 

professional judgment of the entire database on the chemical. The RfDs are not applicable to 

nonthreshold effects such as cancer. 

Reportable Quantity (RQ)—The quantity of a hazardous substance that is considered reportable under 

the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Reportable 

quantities are (1) 1 pound or greater or (2) for selected substances, an amount established by regulation 

either under CERCLA or under Section 311 of the Clean Water Act. Quantities are measured over a 

24-hour period. 

Reproductive Toxicity—The occurrence of adverse effects on the reproductive system that may result 

from exposure to a chemical. The toxicity may be directed to the reproductive organs and/or the related 

endocrine system. The manifestation of such toxicity may be noted as alterations in sexual behavior, 

fertility, pregnancy outcomes, or modifications in other functions that are dependent on the integrity of 

this system. 

Retrospective Study—A type of cohort study based on a group of persons known to have been exposed 

at some time in the past. Data are collected from routinely recorded events, up to the time the study is 

undertaken. Retrospective studies are limited to causal factors that can be ascertained from existing 

records and/or examining survivors of the cohort. 

Risk—The possibility or chance that some adverse effect will result from a given exposure to a chemical. 
 

 

 

 

 

ETHYLENE GLYCOL 254 

10. GLOSSARY 

Risk Factor—An aspect of personal behavior or lifestyle, an environmental exposure, or an inborn or 

inherited characteristic that is associated with an increased occurrence of disease or other health-related 

event or condition. 

Risk Ratio—The ratio of the risk among persons with specific risk factors compared to the risk among 

persons without risk factors. A risk ratio greater than 1 indicates greater risk of disease in the exposed 

group compared to the unexposed group. 

Short-Term Exposure Limit (STEL)—The American Conference of Governmental Industrial 

Hygienists (ACGIH) maximum concentration to which workers can be exposed for up to 15 minutes 

continually. No more than four excursions are allowed per day, and there must be at least 60 minutes 

between exposure periods. The daily Threshold Limit Value-Time Weighted Average (TLV-TWA) may 

not be exceeded. 

Standardized Mortality Ratio (SMR)—A ratio of the observed number of deaths and the expected 

number of deaths in a specific standard population. 

Target Organ Toxicity—This term covers a broad range of adverse effects on target organs or 

physiological systems (e.g., renal, cardiovascular) extending from those arising through a single limited 

exposure to those assumed over a lifetime of exposure to a chemical. 

Teratogen—A chemical that causes structural defects that affect the development of an organism. 

Threshold Limit Value (TLV)—An American Conference of Governmental Industrial Hygienists 

(ACGIH) concentration of a substance to which most workers can be exposed without adverse effect. 

The TLV may be expressed as a Time Weighted Average (TWA), as a Short-Term Exposure Limit 

(STEL), or as a ceiling limit (CL). 

Time-Weighted Average (TWA)—An allowable exposure concentration averaged over a normal 8-hour 

workday or 40-hour workweek. 

Toxic Dose(50) (TD50)—A calculated dose of a chemical, introduced by a route other than inhalation, 

which is expected to cause a specific toxic effect in 50% of a defined experimental animal population. 

Toxicokinetic—The absorption, distribution, and elimination of toxic compounds in the living organism. 

Uncertainty Factor (UF)—A factor used in operationally deriving the Minimal Risk Level (MRL) or 

Reference Dose (RfD) or Reference Concentration (RfC) from experimental data. UFs are intended to 

account for (1) the variation in sensitivity among the members of the human population, (2) the 

uncertainty in extrapolating animal data to the case of human, (3) the uncertainty in extrapolating from 

data obtained in a study that is of less than lifetime exposure, and (4) the uncertainty in using lowestobserved-adverse-effect level (LOAEL) data rather than no-observed-adverse-effect level (NOAEL) data. 

A default for each individual UF is 10; if complete certainty in data exists, a value of 1 can be used; 

however, a reduced UF of 3 may be used on a case-by-case basis, 3 being the approximate logarithmic 

average of 10 and 1. 

Xenobiotic—Any chemical that is foreign to the biological system. 
 

 

 

 

ETHYLENE GLYCOL A-1 

APPENDIX A. ATSDR MINIMAL RISK LEVELS AND WORKSHEETS 

The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) [42 U.S.C. 

9601 et seq.], as amended by the Superfund Amendments and Reauthorization Act (SARA) [Pub. L. 99– 

499], requires that the Agency for Toxic Substances and Disease Registry (ATSDR) develop jointly with 

the U.S. Environmental Protection Agency (EPA), in order of priority, a list of hazardous substances most 

commonly found at facilities on the CERCLA National Priorities List (NPL); prepare toxicological 

profiles for each substance included on the priority list of hazardous substances; and assure the initiation 

of a research program to fill identified data needs associated with the substances. 

The toxicological profiles include an examination, summary, and interpretation of available toxicological 

information and epidemiologic evaluations of a hazardous substance. During the development of 

toxicological profiles, Minimal Risk Levels (MRLs) are derived when reliable and sufficient data exist to 

identify the target organ(s) of effect or the most sensitive health effect(s) for a specific duration for a 

given route of exposure. An MRL is an estimate of the daily human exposure to a hazardous substance 

that is likely to be without appreciable risk of adverse noncancer health effects over a specified duration 

of exposure. MRLs are based on noncancer health effects only and are not based on a consideration of 

cancer effects. These substance-specific estimates, which are intended to serve as screening levels, are 

used by ATSDR health assessors to identify contaminants and potential health effects that may be of 

concern at hazardous waste sites. It is important to note that MRLs are not intended to define clean-up or 

action levels. 

MRLs are derived for hazardous substances using the no-observed-adverse-effect level/uncertainty factor 

approach. They are below levels that might cause adverse health effects in the people most sensitive to 

such chemical-induced effects. MRLs are derived for acute (1–14 days), intermediate (15–364 days), and 

chronic (365 days and longer) durations and for the oral and inhalation routes of exposure. Currently, 

MRLs for the dermal route of exposure are not derived because ATSDR has not yet identified a method 

suitable for this route of exposure. MRLs are generally based on the most sensitive chemical-induced end 

point considered to be of relevance to humans. Serious health effects (such as irreparable damage to the 

liver or kidneys, or birth defects) are not used as a basis for establishing MRLs. Exposure to a level 

above the MRL does not mean that adverse health effects will occur. 

MRLs are intended only to serve as a screening tool to help public health professionals decide where to 

look more closely. They may also be viewed as a mechanism to identify those hazardous waste sites that 
 

 

 

ETHYLENE GLYCOL A-2 

APPENDIX A 

are not expected to cause adverse health effects. Most MRLs contain a degree of uncertainty because of 

the lack of precise toxicological information on the people who might be most sensitive (e.g., infants, 

elderly, nutritionally or immunologically compromised) to the effects of hazardous substances. ATSDR 

uses a conservative (i.e., protective) approach to address this uncertainty consistent with the public health 

principle of prevention. Although human data are preferred, MRLs often must be based on animal studies 

because relevant human studies are lacking. In the absence of evidence to the contrary, ATSDR assumes 

that humans are more sensitive to the effects of hazardous substance than animals and that certain persons 

may be particularly sensitive. Thus, the resulting MRL may be as much as 100-fold below levels that 

have been shown to be nontoxic in laboratory animals. 

Proposed MRLs undergo a rigorous review process: Health Effects/MRL Workgroup reviews within the 

Division of Toxicology and Environmental Medicine, expert panel peer reviews, and agency-wide MRL 

Workgroup reviews, with participation from other federal agencies and comments from the public. They 

are subject to change as new information becomes available concomitant with updating the toxicological 

profiles. Thus, MRLs in the most recent toxicological profiles supersede previously published levels. 

For additional information regarding MRLs, please contact the Division of Toxicology and 

Environmental Medicine, Agency for Toxic Substances and Disease Registry, 1600 Clifton Road NE, 

Mailstop F-62, Atlanta, Georgia 30333. 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL A-3 

APPENDIX A 

MINIMAL RISK LEVEL (MRL) WORKSHEET 

Chemical name(s): Ethylene glycol 

CAS number(s): 107-21-1 

Date: May 2010 

Profile status: Final Draft Post-Public Comment 

Route: [X] Inhalation [ ] Oral 

Duration: [X] Acute [ ] Intermediate [ ] Chronic 

Key to figure: 2 

Species: Human 

MRL: 2 [ ] mg/kg/day [ ] ppm [X] mg/m3 

Reference: Wills JH, Coulston F, Harris ES, et al. 1974. Inhalation of aerosolized ethylene glycol by 

man. Clin Toxicol 7(5):463-476. 

Experimental design: Health effects were assessed in 19 male prisoners who voluntarily were exposed to 

ethylene glycol aerosol for 20–22 hours/day for 30 days. The diameter of the aerosol droplets ranged 

from 1 to 5 μm. Mean daily and mean weekly concentrations during the first 14 days of the study were 

0.8–44.8 and 17–29 mg/m3

, respectively. Mean daily and mean weekly concentrations during the entire 

30-day exposure period were 0.8–67 and 17–49 mg/m3

, respectively. The average mean weekly 

exposures were 23 mg/m3 for days 1–14 and 30 mg/m3 for days 1–30. The average exposure levels did 

not include brief periods in which the concentration was intentionally raised to higher levels to assess 

acute responses. A control group consisted of 14 male prisoners; 10 of these men were never exposed to 

ethylene glycol, whereas the remaining 4 men had been exposed to a mean concentration of 37 mg/m3 for 

20–22 hours/day for 7 days during the week that preceded the start of the study. Subjective responses 

(symptoms) were monitored throughout the study. During the last 10 days of the study, the concentration 

of ethylene glycol was occasionally intentionally increased to various high levels (up to 308 mg/m3

) when 

the volunteers left the exposure chamber during meals; subjective responses to short exposures to the high 

concentrations were assessed when they reentered the chamber. Complete physical examinations that 

included slit-lamp, electrocardiographic, and electroencephalographic studies, and a battery of 

psychological tests designed to reveal effects on simple reaction time, reaction time with discrimination, 

visual-motor coordination, depth perception, and mental ability (encoding and subtraction accuracy), were 

conducted on all subjects pre-exposure and after 14 and 30 days of exposure. Blood samples were 

collected on days 0, 1, 3, 5, 8, 12, 19, 22, 26, and 29 for evaluation of hematology, clinical chemistry 

(including blood urea nitrogen, serum creatinine, and liver enzymes), and ethylene glycol concentration. 

Urine was evaluated daily for oxalate crystals, erythrocytes, and ethylene glycol, and twice weekly for 

volume, specific gravity, color, clarity, pH, amino acid nitrogen, and creatinine. 

Effects noted in study and corresponding doses: Concentrations of ethylene glycol in the blood and urine 

were similar in the exposed and control groups. The near-continuous exposure levels (average 23 mg/m3 

for days 1–14 and 30 mg/m3 for days 1–30) were tolerated with effects that were limited to occasional 

complaints of upper respiratory tract irritation, slight headache, and low backache (incidences and other 

information not reported). The short-term, high-exposure sessions showed that the irritation became 

common at approximately 140 mg/m3

, and tolerated for only 15 minutes at 188 mg/m3, 2 minutes at 

244 mg/m3

, and one or two breaths at 308 mg/m3. Based on these results and those of other trials, the 

investigators concluded that concentrations of about ≥200mg/m3 were intolerable due to strong irritation 

of the upper respiratory tract that included a burning sensation in the trachea and a burning cough. 

Because the near-continuous exposures were tolerated with respiratory irritation that was infrequent and 

not serious, and not accompanied by neurological, hematology, clinical chemistry, or urinalysis findings 

indicative of renal or other systemic effects, the interim (12–14-day) findings in this study identified a 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL A-4 

APPENDIX A 

NOAEL of 23 mg/m3 for acute-duration exposure in humans. The LOAEL was 140 mg/m3 because brief 

exposures to this concentration commonly caused respiratory irritation. 

Dose and end point used for MRL derivation: 

[X] NOAEL [ ] LOAEL 

Uncertainty factors used in MRL derivation: 

[ ] 10 for use of a LOAEL 

[ ] 10 for extrapolation from animals to humans 

[X] 10 for human variability 

Was a conversion factor used from ppm in food or water to a mg/body weight dose? Not applicable 

(inhalation study). 

If an inhalation study in animals, list conversion factors used in determining human equivalent dose: Not 

applicable (human study). 

Exposure concentrations were not converted from mg/m3 to ppm because ppm is unsuitable for aerosols. 

Was a conversion used from intermittent to continuous exposure? The NOAEL of 23 mg/m3 was not 

adjusted for discontinuous daily exposure (20 hours/24 hours) because the critical effect is concentration 

dependent and not duration dependent. 

Other additional studies or pertinent information that lend support to this MRL: The only other 

information on effects of acute-duration inhalation exposure to ethylene glycol is available from three 

developmental toxicity studies in rats and mice (Tyl 1988a; Tyl et al. 1995a, 1995b). 

In a developmental toxicity study in CD-1 mice using whole-body exposure to nominal concentrations of 

0, 150, 1,000, or 2,500 mg/m3 for 6 hours/day on Gd 6–15, maternal body weight gain was decreased, but 

corrected weight was unaffected, at concentrations ≥1,000 mg/m3 (Tyl 1988a; Tyl et al. 1995a). 

Significant effects on implant viability, weight of live fetuses, and on the incidence of external, visceral, 

and skeletal malformations were observed at concentrations ≥1,000mg/m3

. Maternal toxicity (e.g., 

increased liver weight in rats and reduced body weight gain in mice) was evident at 2,500 and 

1,000 mg/m3 in rats and mice, respectively (Tyl et al. 1995a). In CD rats exposed similarly in the same 

study, there were significant increases in absolute and relative liver weight among maternal animals 

exposed to 2,500 mg/m3

; kidney weights were unchanged, and liver and kidney histopathology was not 

evaluated. In addition, reduced ossification at some sites in the axial skeleton was observed with 

exposure to 1,000 and 2,500 mg/m3

; however, in an Expert Panel Review of this study, NTP-CERHR 

(2004) concluded that the relationship of this effect to treatment was uncertain due to the lack of a doseresponse relationship. Both of the whole-body experiments were confounded by significant ingestion of 

ethylene glycol deposited on the fur and consumed during grooming; the authors estimated that the 

ingestion dose comprised the majority of exposure (Tyl 1985, 1988a; Tyl et al. 1995a). 

In a follow-up developmental study aimed at reducing the confounding from ingestion exposure, pregnant 

CD-1 mice were exposed nose-only to target concentrations of 0, 500, 1,000, or 2,500 mg/m3 aerosolized 

ethylene glycol for 6 hours/day on Gd 6–15 (Tyl 1988a; Tyl et al. 1995b). In maternal animals, there 

were no effects other than changes in kidney weights. Absolute kidney weight was significantly 

increased at 1,000 and 2,500 mg/mg3

, and relative kidney weight was increased at 2,500 mg/m3; however, 

microscopic examination of kidneys did not indicate any histopathological changes. At 2,500 mg/m3

, live 
 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL A-5 

APPENDIX A 

fetal body weight was significantly reduced, and there was a significant increase in the one type of 

skeletal malformation (fused ribs). Increases in some skeletal variations were observed at 2,500 mg/m3

, 

and one type (extra ossification sites in the sagittal suture) was significantly increased at concentrations 

≥500 mg/m3

. The authors designated the 1,000 mg/m3 concentration a developmental NOAEL and the 

500 mg/m3 concentration a NOAEL for maternal effects. However, the authors noted that the animals in 

the nose-only experiment were also exposed by ingestion of ethylene glycol during preening of the face 

after exposure (Tyl 1988a; Tyl et al. 1995b). Furthermore, NTP-CERHR (2004) noted that stress from 

restraint in the single nose-only exposure study may have contributed to the developmental effects 

observed with ethylene glycol, which were similar in nature to effects observed in a study of restrained 

nose-only exposure to water vapor (Tyl et al. 1994). 

Because of the confounding oral exposures in both the whole-body and nose-only developmental toxicity 

studies, NTP-CERHR (2004) concluded that the data from these studies were not suitable for evaluation 

of effect levels from inhalation exposure to ethylene glycol. The available data do, however, provide a 

conservative estimate of the inhalation NOAEL, with the caveat that total exposure to ethylene glycol in 

these studies included intake via ingestion. Collectively, these studies suggest that inhalation exposure to 

ethylene glycol at a nominal concentration of about 150 mg/m3 is not associated with developmental 

toxicity in mice or rats, or renal toxicity in mice (kidney histopathology not assessed in rats). The next 

highest concentration (500 mg/m3 in the nose-only study) was associated with developmental effects 

(increased incidence of skeletal variations), but it is not possible to conclusively relate these effects to 

inhalation of ethylene glycol. 

As indicated above, the developmental studies (Tyl 1988a; Tyl et al. 1995a, 1995b) collectively suggest 

that 150 mg/m3 is a conservative NOAEL for developmental toxicity in rats and kidney toxicity in mice. 

This concentration is similar to the 140 mg/m3 LOAEL for respiratory tract irritation in humans (Wills et 

al. 1974). The human NOAEL of 23 mg/m3 is a suitable basis for MRL derivation because it is based on 

evaluations for renal and other systemic effects as well as for local irritation, and is well within the 

NOAEL range for developmental toxicity in animals. 

Agency Contacts (Chemical Managers): Obaid Faroon, Carolyn Tylenda, Carolyn C. Harper 
 

 

ETHYLENE GLYCOL A-6 

APPENDIX A 

MINIMAL RISK LEVEL WORKSHEET 

Chemical name(s): Ethylene glycol 

CAS number(s): 107-21-1 

Date: May 2010 

Profile status: Final Draft Post-Public Comment 

Route: [ ] Inhalation [X] Oral 

Duration: [X] Acute [ ] Intermediate [ ] Chronic 

Key to figure: 51 

Species: Mouse 

MRL: 0.8 [X] mg/kg/day [ ] ppm [ ] mg/m3 

References: Neeper-Bradley TL, Tyl RW, Fisher LC, et al. 1995. Determination of a no-observed-effect 

level for developmental toxicity of ethylene glycol administered by gavage to CD rats and CD-1 mice. 

Fundam Appl Toxicol 27:121-130. 

Tyl RW. 1989. Developmental toxicity evaluation of ethylene glycol administrated by gavage to 

CD-1 mice: Determination of a "no-observed-effect-level" (NOEL). Bushy Run Research Center, CMA 

Project Report 51-591. 

Experimental design: Groups of 30 timed-pregnant CD-1 mice were given doses of 50, 150, 500, or 

1,500 mg/kg ethylene glycol daily by gavage on Gd 6–15; vehicle controls were given water on the same 

schedule (Neeper-Bradley et al. 1995; Tyl 1989). Maternal animals were observed daily for clinical signs 

and weighed periodically; water intake was measured throughout gestation. At sacrifice on Gd 18, body 

weight, gravid uterine weight, liver weight, and kidney weight were measured in dams. Kidneys from 

control and high-dose dams were examined microscopically. Corpora lutea and uterine contents were 

evaluated, and live fetuses were weighed and sexed. External, visceral, and skeletal malformations and 

variations in the fetuses were evaluated. 

Effects noted in study and corresponding doses: No effects on maternal body weight, water consumption, 

or liver or kidney weight were observed. There were no significant effects on the number of corpora 

lutea/dam, on the number of total, nonviable, or viable implants/litter, or on sex ratio. Average fetal body 

weight per litter was reduced (13% below controls) at 1,500 mg/kg/day. The incidence of individual 

external or visceral malformations was not significantly increased in any treatment group relative to the 

vehicle control; however, exencephaly (a malformation observed by Price et al. [1985] at higher doses) 

was observed in two fetuses in the 500 mg/kg/day group and in three fetuses of the 1,500 mg/kg/day dose 

group. There was a significant increase in the incidence of two skeletal malformations (fused ribs or 

thoracic arches) in the 1,500 mg/kg/day group (15/21 litters with fused ribs vs. 1/19 controls; 8/21 litters 

with fused thoracic arches vs. 0/19 controls). Further, the incidence of total malformations per litter 

(external, visceral, and skeletal) was significantly increased both at 500 and 1,500 mg/kg/day (3/19, 7/20, 

5/24, 12/24, and 17/21 from control to high dose). The incidences of 23 skeletal variations were 

increased in the 1,500 mg/kg/day group. One of these variations (bilateral extra rib 14) was also 

significantly increased at ≥500 mg/kg/day (4/19, 4/20, 6/24, 17/24, and 21/21 in control through highdose groups, respectively). This study identified a developmental NOAEL of 150 mg/kg/day and a 

LOAEL of 500 mg/kg/day for increased incidence of total malformations and bilateral extra rib 14. The 

high dose (1,500 mg/kg/day) was a NOAEL for maternal effects. 

Dose and end point used for MRL derivation: 

[ ] NOAEL [ ] LOAEL [X] BMDL 
 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL A-7 

APPENDIX A 

To derive a point of departure for MRL derivation, BMD dose modeling was conducted using the mouse 

data on the incidence of litters with malformations (of any kind) and on the incidence of one skeletal 

variation (bilateral extra rib 14). The incidences for both end points are presented in Table A-1. These 

two end points were observed at lower doses than other observed effects (skeletal malformations, pup 

body weight reductions). 

Table A-1. Incidences of Developmental Effects in Offspring of Mice Exposed 

to Ethylene Glycol by Gavage on Gestation Days 6–15 

Dose (mg/kg/day) 

Effecta 0 50 150 500 1,500 

Extra lumbar ribb 4/19 4/20 6/24 17/24c 21/21c 

Total malformations 3/19 7/20 5/24 12/24d 17/21c 

a

Number of litters with effects/number of litters examined.

b

Extra rib 14, first lumbar arch, bilateral.
 c

p<0.01.

d

p<0.05.
 

Sources: Neeper-Bradley et al. 1995; Tyl 1989 

All dichotomous models in the EPA Benchmark Dose Software (Version 2.1.1) were fit to the 

malformation and skeletal variation incidence data. Although one of the end points modeled (total 

malformations) represents a more serious effect, the group sizes in this study (19–24 litters/dose 

examined) did not support a BMR lower than 10%; thus, an extra risk incidence of 10% above controls 

was selected as the BMR. Model results for the data on total malformations are shown in Table A-2. All 

dichotomous models provided adequate fit to the data (p>0.1). Among all of the models providing 

adequate fit to the data, a better fit is generally indicated by a lower Akaike’s Information Criteria (AIC) 

and the BMDL associated with the lowest AIC value is selected as the point of departure (POD) for risk 

assessment. However, when the BMDLs from the models providing adequate fit vary by more than 

3-fold, some model dependence is assumed, and the lowest BMDL is selected as a reasonable 

conservative estimate unless it appears to be an outlier (i.e., other BMDL values all range within 3-fold of 

one another). Although the BMDLs from the models providing adequate fit to the data on total 

malformations varied by more than 3-fold (range 48.14–159.25) mg/kg/day, the BMDL10 of 

48.14 mg/kg/day appears to be an outlier and is not considered further. Among the remaining BMDLs, 

which vary by less than 3-fold, the model with the lowest AIC is considered to represent the best fit to the 

data. The multistage and quantal linear models converged on the same model providing the best fit (as 

assessed by AIC) to the data on total malformations; these models both predicted a BMD10 of 

113.84 mg/kg/day and a BMDL10 of 75.59 mg/kg/day. Figure A-1 shows the fit of the multistage 

(1-degree polynomial) model to the malformation data. 
 

 

 

ETHYLENE GLYCOL A-8 

APPENDIX A 

Table A-2. Model Predictions for the Incidence of Total Malformations in 

Offspring of Mice Exposed to Ethylene Glycol by
 

Gavage on Gestation Days 6–15
 

BMD10 BMDL10 

Model (mg/kg/day) (mg/kg/day) χ2 p-value AIC 

Gammaa 162.50 75.95 0.27 129.33 

Logistic 211.23 156.53 0.41 127.64 

Log-logisticb 213.64 48.14 0.28 129.24 

Log-probitb 242.07 140.87 0.28 129.21 

Multi-stagec 113.84 75.59 0.44 127.40 

Probit 208.48 159.25 0.41 127.66 

Weibulla 152.27 75.98 0.27 129.33 

Quantal linear 113.84 75.59 0.44 127.40 

a

Power restricted to ≥1. b

Slope restricted to ≥1. c

Betas restricted to ≥0; lowest degree polynomial with adequate fit is reported; degree of polynomial = 1. 

AIC = Akaike Information Criterion; BMD = maximum likelihood estimate of the dose associated with the selected 

benchmark response; BMDL = 95% lower confidence limit on the BMD 

Sources: Neeper-Bradley et al. 1995; Tyl 1989 

Figure A-1. Predicted and Observed Incidence of Total Malformations in 

Offspring of Mice Exposed to Ethylene Glycol
 

by Gavage on Gestation Days 6–15*

Fraction Affected 

0

 0.2

 0.4

 0.6

 0.8

 1

 0 200 400 600 800 1000 1200 1400 

dose 

Multistage Model with 0.95 Confidence Level 

BMDL BMD

Multistage 

10:05 02/02 2010 

*BMD and BMDL associated with a 10% extra risk increase over control are shown; doses given in units of 

mg/kg/day. 

Sources: Neeper-Bradley et al. 1995; Tyl 1989 
 

 

 

ETHYLENE GLYCOL A-9 

APPENDIX A 

Model results for the data on bilateral extra rib 14 are shown in Table A-3. For these data, the probit 

model provided the best fit (as assessed by AIC); a BMD10 of 99.35 mg/kg/day and BMDL10 of 

75.56 mg/kg/day were predicted. Figure A-2 shows the fit of the probit model to the skeletal variation 

data. 

Table A-3. Model Predictions for the Incidence of Bilateral Extra Lumbar
 

Ribs in Offspring of Mice Exposed to Ethylene Glycol
 

by Gavage on Gestation Days 6–15
 

Model 

Gammaa 

BMD10 

(mg/kg/day) 

200.89 

BMDL10 

(mg/kg/day) 

64.02 

χ2 p-value 

0.98 

AIC 

101.59 

Logistic 

Log-logisticb 

Log-probitb 

103.80 

419.85 

353.71 

77.82 

101.67 

97.62 

0.90 

0.91 

0.91 

100.16 

101.72 

101.72 

Multi-stagec 

Probit 

49.96 

99.35 

35.31 

75.56 

0.36 

0.90 

103.53 

100.12 

Weibulla 192.89 60.78 0.99 101.55 

Quantal linear 49.96 35.31 0.36 103.53 

a

Power restricted to ≥1. b

Slope restricted to ≥1. c

Betas restricted to ≥0; lowest degree polynomial with adequate fit is reported; degree of polynomial = 1. 

AIC = Akaike’s Information Criterion; BMD = maximum likelihood estimate of the dose associated with the selected 

benchmark response; BMDL = 95% lower confidence limit on the BMD 

Sources: Neeper-Bradley et al. 1995; Tyl 1989 
 

 

 

 

 

 

ETHYLENE GLYCOL A-10 

APPENDIX A 

Figure A-2. Predicted and Observed Incidence of Extra Lumbar Ribs in Offspring 

of Mice Exposed to Ethylene Glycol by Gavage on Gestation Days 6–15* Fraction Affected 

0.8

 0.6

 0.4

 0.2

 0

 1

 0 200 400 600 800 1000 1200 1400 

dose 

Probit Model with 0.95 Confidence Level 

BMDL BMD 

Probit 

14:44 02/03 2010 

*BMD and BMDL associated with a 10% extra risk increase over control are shown; doses given in units of 

mg/kg/day. 

Sources: Neeper-Bradley et al. 1995; Tyl 1989 

Modeling of both the malformation and skeletal variation end points resulted in the same BMDL10, 

indicating that an acute oral MRL based on this point of departure should provide protection against both 

effects. 

Uncertainty factors used in MRL derivation: 

[ ] 10 for use of a LOAEL 

[X] 10 for extrapolation from animals to humans 

[X] 10 for human variability 

Although some mechanistic information suggests that humans may be less sensitive than rodents to the 

developmental effects of ethylene glycol, the available data are not adequate to support a lower 

interspecies uncertainty factor; thus, a full 10-fold uncertainty factor was used for interspecies 

extrapolation. While in vitro data suggest that humans metabolize glycolic acid (the proximate 

developmental toxicant) more efficiently than rats (Booth et al. 2004; Corley et al. 2005), NTP-CERHR 

(2004) observed that the data supporting the glycolic acid metabolic rate in humans are limited. In 

addition, NTP-CERHR (2004) reviewed preliminary data indicating that the inverted yolk sac placenta, a 

stage in placental development that does not exist in humans, tends to concentrate weak acids such as 

glycolic acid in the embryonic fluids. These data suggest enhanced sensitivity to ethylene glycol 

developmental effects in rodents compared with humans; however, NTP-CERHR (2004) characterized 

the available data as inconclusive. A 10-fold uncertainty factor for interindividual variability was also 

used. Ethylene glycol metabolism is known to involve alcohol dehydrogenase and aldehyde 

dehydrogenase, and may also involve cytochrome p450 isozymes (NTP-CERHR 2004). Polymorphisms 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL A-11 

APPENDIX A 

in the genes encoding these enzymes may lead to wide variability in the production and elimination of 

glycolic acid and other metabolites in humans exposed to ethylene glycol, but data quantifying the range 

of variability are not currently available (NTP-CERHR 2004). In addition, fetal and/or placental 

differences in expression of these enzymes over the course of gestation will affect local concentrations of 

glycolic acid and other metabolites to which the developing conceptus is exposed, yet little is known 

about these differences (NTP-CERHR 2004). 

Was a conversion factor used from ppm in food or water to a mg/body weight dose? Not applicable 

(gavage study). 

If an inhalation study in animals, list conversion factors used in determining human equivalent dose: Not 

applicable. 

Was a conversion used from intermittent to continuous exposure? Not applicable. 

Other additional studies or pertinent information that lend support to this MRL: In acute-duration oral 

developmental toxicity studies in rodents, fetal effects have consistently been observed at doses that are 

not maternally toxic. Furthermore, the teratogenic effects observed after ethylene glycol exposure appear 

to be generally consistent across studies and across species, with the primary end point consisting of 

skeletal malformations. The incidence of malformations was increased in CD-1 mice at doses of 

≥500 mg/kg/day when administered by gavage during gestation (Gd 6–15) (Neeper-Bradley et al. 1995; 

Tyl 1989). Embryotoxicity was also manifested as a reduction in fetal body weight in CD-1 mice given 

doses of ≥750 mg/kg/day on Gd 6–15 (Neeper-Bradley 1990; Price et al. 1985; Tyl 1989). In rats, doses 

of ≥1,000 mg/kg/day by gavage on Gd 6–15 resulted in an increased incidence of skeletal malformations 

in offspring (Neeper-Bradley 1990; Neeper-Bradley et al. 1995; Price et al. 1985). Decreases in pup body 

weight and increases in both the number of litters with malformations and the number of malformed 

fetuses per litter were observed in rats treated during Gd 6–15 with doses ≥2,500 mg/kg/day (Price et al. 

1985; Neeper-Bradley 1990; Neeper-Bradley et al. 1995). In mice given doses of 3,000 mg/kg/day during 

Gd 6–15, neural tube and craniofacial defects were increased, and the number of live fetuses per litter was 

decreased (Price et al. 1985). In contrast to the results in rodents, no teratogenic effects were observed in 

rabbits exposed to maternally lethal doses of 2,000 mg/kg/day during gestation (Tyl et al. 1993). 

No effects were observed on hematology parameters, but dose-related effects on bone marrow and 

erythropoiesis were observed when doses of 0, 50, 100, or 250 mg/kg/day ethylene glycol were given for 

4 consecutive days by gavage to B6C3F1 mice. Seven mice per sex were sacrificed on 1 day 

postexposure for measurement of body, liver, thymus, spleen, kidney, and testis weights, and 

histopathology of these organs as well as the lung, heart, adrenals, stomach, bone marrow, urinary 

bladder, intestines, and uterus. Hematology, bone marrow parameters, and erythropoiesis were evaluated 

in other groups of mice evaluated between 1 and 14 days after exposure. Microscopic examination of the 

spleen and bone marrow did not reveal any histopathological changes, and there were no significant 

changes to hematological parameters (hemoglobin, hematocrit, mean corpuscular volume, erythrocyte and 

leukocyte counts) evaluated 5 days after exposure termination. Exposure to ethylene glycol resulted in 

statistically significant decreases in bone marrow cellularity (up to about 25% below control values) at 

doses of ≥100 mg/kg/day; this effect persisted up to 14 days after exposure in males. Granulocytemacrophage progenitor formation was suppressed (~15% below controls) at 50 mg/kg/day in males 

evaluated 14 days postexposure and at higher doses in both males and females evaluated at earlier time 

points. The magnitude of reduction in granulocyte-macrophage progenitor formation ranged up to 40% 

below controls at 250 mg/kg/day. Iron uptake in the bone marrow was suppressed (38% below controls) 

in males exposed to 250 mg/kg/day. 
 

 

 

 

 

 

 

ETHYLENE GLYCOL A-12 

APPENDIX A 

While bone marrow effects were observed in male mice exposed to doses of 50–250 mg/kg/day in this 

study, the biological significance of these effects is uncertain. No effects were observed on any 

hematological parameters, or on bone marrow or spleen histology (Hong et al. 1988). Histology was 

evaluated only 1 day after exposure, and hematological parameters were evaluated 5 days postexposure; 

thus, these evaluations would not have captured delayed effects on these parameters. However, studies 

using much higher doses and longer durations have failed to indicate effects on bone marrow, spleen, or 

hematology in mice, and provide inconsistent findings in rats. No histological changes in the bone 

marrow were observed in mice or rats exposed to higher doses of ethylene glycol for longer durations; 

these included B6C3F1 mice exposed to ≤16,000 mg/kg/day in diet for 13 weeks or ≤12,000 mg/kg/day 

in diet for 2 years (Melnick 1984; NTP 1993), F344 rats exposed to ≤10,000 mg/kg/day in diet for 

13 weeks (Melnick 1984), and Sprague-Dawley rats exposed to ≤7,327 mg/kg/day in drinking water for 

10 or 90 days (Robinson et al. 1990). Results of routine hematology evaluations in these studies were 

unremarkable except for some alterations in the 10- and 90-day studies in rats. In the 10-day study, 

statistically significant decreases in hemoglobin, hematocrit, erythrocytes, and total leukocytes (7.3, 8.9, 

8.5, and 34.8% less than controls, respectively) occurred in female rats at 7,327 mg/kg/day (Robinson et 

al. 1990). In the 90-day study, total leukocyte counts were significantly reduced in female rats at 597, 

3,087, and 5,744 mg/kg/day (32, 30, and 50% less than controls, respectively) (Robinson et al. 1990). 

Results of differential counts were not reported, and no clear hematological changes occurred in male rats 

in either study. Hematology evaluations were also negative in other studies that did not examine bone 

marrow histology; these included studies of B6C3F1 mice exposed to ≤12,000 mg/kg/day in diet for 

2 years (DePass et al. 1986a), Wistar rats exposed to ≤2,000mg/kg/day by gavage for 4 weeks (Schladt et 

al. 1998), and Wistar rats exposed to ≤1,128mg/kg/day in diet for 16 weeks (Gaunt et al. 1974). In male 

F344 rats exposed to 1,000 mg/kg/day in the diet for 2 years, significant hematological changes were 

observed, but this dose also caused mortality due to renal toxicity (DePass et al. 1986a). 

The hematopoietic system is an established target system for several ethylene glycol ethers (e.g., ethylene 

glycol monomethyl ether, ethylene glycol monobutyl ether (IRIS 2007). For these compounds, 

hematological effects are consistently observed across different species, doses, and exposure durations. 

In contrast, few studies have suggested hematological effects from ethylene glycol exposure, and those 

with positive findings were at higher doses than Hong et al. (1988) and gave inconsistent results. Given 

the lack of supporting evidence for hematological, bone marrow, or splenic effects in mice and rats 

exposed to much higher doses of ethylene glycol and for longer durations, the biological significance of 

the effects observed by Hong et al. (1988) is considered uncertain, and this study was not used to derive 

the acute oral MRL. 

In a 10-day drinking water study, groups of 10 male and 10 female Sprague-Dawley rats were 

administered 0, 0.5, 1.0, 2.0, or 4.0% ethylene glycol; reported mean compound consumption was 649, 

1,343, 2,615, and 5,279 mg/kg/day in males, and 794, 1,506, 2,953, and 7,327 mg/kg/day in females 

(Robinson et al. 1990). The incidence and severity of renal lesions were significantly increased and doserelated in males at ≥2,615 mg/kg/day; effects included tubular dilation, degeneration, necrosis, and 

intratubular calcium oxalate crystals. Effects on body weight, organ weights, and hematological 

parameters were observed at the high dose only. Changes in serum chemistry parameters were observed 

at lower doses in both males and females; however, these were not accompanied by histopathological 

changes in the liver. This study identified a LOAEL of 2,615 mg/kg/day for renal toxicity in male rats. 

As discussed above, other studies identified bone marrow effects and developmental toxicity at lower 

doses; thus, this study was not considered for use in acute oral MRL derivation. 

Corley et al. (2005) published a PBPK model for rats, but no model has yet been developed for mice, the 

species used in the study selected for MRL derivation. As a result, available data do not support the use 

of PBPK modeling to derive an acute oral MRL for ethylene glycol based on developmental toxicity in 

mice. 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL A-13 

APPENDIX A 

A key uncertainty in the acute-duration oral MRL stems from the use of gavage administration in the 

critical study. Bolus doses from gavage administration lead to higher peak concentrations of glycolic acid 

in the blood than occur with equivalent doses at slower dose-rates associated with environmentallyrelevant exposures (Carney et al. 2001; NTP-CERHR 2004). Because the key study used gavage 

administration, the dose at which effects were observed may be lower than would be observed with nonbolus dosing. In support of this, Maronpot et al. (1983) observed neither fetal nor maternal toxicity at 

dietary doses up to 1,000 mg/kg in F344 rats, while Neeper-Bradley et al. (1995) reported skeletal 

malformations and effects on fetal body weight in CD rats given 1,000 mg/kg via gavage. Data 

supporting glycolic acid as the proximate toxicant (Carney et al. 1996, 1999; Klug et al. 2001; Munley et 

al. 1999), and evidence for much lower serum levels of glycolic acid following slower dose-rate 

administration of ethylene glycol than the fast dose-rate resulting from bolus dosing (Carney et al. 2001, 

2002), suggest that the lack of developmental toxicity observed by Maronpot et al. (1983) likely resulted 

from the difference in dose-rate. However, strain differences in susceptibility to ethylene glycol cannot 

be ruled out as an explanation for the dissimilar results. Neeper-Bradley et al. (1995) also reported 

significantly increased incidences of skeletal variations and malformations in fetuses of CD-1 mice 

administered ethylene glycol by gavage at doses ≥500 mg/kg/day (compared to controls) but not at doses 

≤150 mg/kg/day. Lamb et al (1985) used the same strain of mice (CD-1 strain) in a continuous breeding 

study in which groups of mice were exposed to ethylene glycol in the drinking water at concentrations of 

0, 0.25, 0.5, or 1% (estimated doses of 0, 410, 840, or 1,640 mg/kg/day) for the entire study period, which 

began in the F0 females prior to mating and continued to weaning of the final F1 generation produced 

during 14 weeks of 1:1 cohabitation with a male. Unusual facial features (shorter snout, wide-set eyes) 

were observed in some of the high-dose F1 offspring and further skeletal examination with Alizarin Red 

in 4 mice/sex/group revealed a pattern of skeletal defects that included shortened skull bones, fused ribs, 

abnormally shaped or missing sternebrae, and abnormal vertebrae. None of these defects were observed 

in examined control mice. Although the study authors stated that neither the low- nor mid-dose groups 

were significantly affected, it appears that this statement refers to gross observations, not the more 

detailed skeletal examinations performed on high-dose offspring. Thus, the study of Lamb et al. (1985) 

did not identify a definitive NOAEL and a direct comparison between the effects of high dose-rate (bolus 

gavage) and slower dose-rate (drinking water consumption) exposure within the same strain of mice 

cannot be made. 

Agency Contacts (Chemical Managers): Obaid Faroon, Carolyn Tylenda, Carolyn C. Harper 
 

 

 

 

ETHYLENE GLYCOL A-14 

APPENDIX A 

MINIMAL RISK LEVEL WORKSHEET 

Chemical name(s): Ethylene glycol 

CAS number(s): 107-21-1 

Date: May 2010 

Profile status: Final Draft Post-Public Comment 

Route: [ ] Inhalation [X] Oral 

Duration: [ ] Acute [X] Intermediate [ ] Chronic 

Key to figure: 51 

Species: Mouse 

MRL: 0.8 [X] mg/kg/day [ ] ppm [ ] mg/m3 

References: Neeper-Bradley TL, Tyl RW, Fisher LC, et al. 1995. Determination of a no-observed-effect 

level for developmental toxicity of ethylene glycol administered by gavage to CD rats and CD-1 mice. 

Fundam Appl Toxicol 27:121-130. 

Tyl RW. 1989. Developmental toxicity evaluation of ethylene glycol administrated by gavage to 

CD-1 mice: Determination of a "no-observed-effect-level" (NOEL). Bushy Run Research Center, CMA 

Project Report 51-591. 

Rationale for the intermediate-duration oral MRL: The database of information regarding the effects of 

intermediate-duration oral exposure of animals to ethylene glycol indicates that a 16-week oral study in 

rats (Cruzan et al. 2004) is the most suitable basis for intermediate-duration oral MRL derivation because 

it identified the lowest reliable LOAEL and has no confounding factors. Incidences of the critical effect, 

crystal nephropathy, were 0/10, 0/10, 0/10, 10/10, and 10/10 at 0, 50, 150, 500, and 1,000 mg/kg/day, 

respectively. This data set is not appropriate for BMD analysis because the incidences increased from 0% 

at doses ≤150 mg/kg/day to 100% at doses ≤500 mg/kg/day; the lack of low-response data points limits 

the accuracy of dose-response modeling. Selection of the NOAEL of 150 mg/kg/day as a point of 

departure and application of an uncertainty factor of 100 (10 for animal to human extrapolation and 10 for 

human variability) yield an intermediate-duration oral MRL of 1.5 mg/kg/day, but this value is higher 

than the acute-duration oral MRL of 0.8 mg/kg/day. The acute-duration oral MRL was derived from a 

study that identified a NOAEL of 150 mg/kg/day for developmental toxicity in mice (Neeper-Bradley et 

al. 1995; Tyl 1989), which is the same as the intermediate- and chronic-duration NOAELs for kidney 

effects in male Wistar rats (Corley et al. 2008; Cruzan et al. 2004). Because available evidence indicates 

that the acute-duration oral MRL for ethylene should be protective for kidney effects following longerterm exposure, the acute-duration value of 0.8 mg/kg/day is adopted for intermediate-duration exposure. 

Agency Contacts (Chemical Managers): Obaid Faroon, Carolyn Tylenda, Carolyn C. Harper 
 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL B-1 

APPENDIX B. USER'S GUIDE 

Chapter 1 

Public Health Statement 

This chapter of the profile is a health effects summary written in non-technical language. Its intended 

audience is the general public, especially people living in the vicinity of a hazardous waste site or 

chemical release. If the Public Health Statement were removed from the rest of the document, it would 

still communicate to the lay public essential information about the chemical. 

The major headings in the Public Health Statement are useful to find specific topics of concern. The 

topics are written in a question and answer format. The answer to each question includes a sentence that 

will direct the reader to chapters in the profile that will provide more information on the given topic. 

Chapter 2 

Relevance to Public Health 

This chapter provides a health effects summary based on evaluations of existing toxicologic, 

epidemiologic, and toxicokinetic information. This summary is designed to present interpretive, weightof-evidence discussions for human health end points by addressing the following questions: 

1.	 What effects are known to occur in humans? 

2.	 What effects observed in animals are likely to be of concern to humans? 

3.	 What exposure conditions are likely to be of concern to humans, especially around hazardous 

waste sites? 

The chapter covers end points in the same order that they appear within the Discussion of Health Effects 

by Route of Exposure section, by route (inhalation, oral, and dermal) and within route by effect. Human 

data are presented first, then animal data. Both are organized by duration (acute, intermediate, chronic). 

In vitro data and data from parenteral routes (intramuscular, intravenous, subcutaneous, etc.) are also 

considered in this chapter. 

The carcinogenic potential of the profiled substance is qualitatively evaluated, when appropriate, using 

existing toxicokinetic, genotoxic, and carcinogenic data. ATSDR does not currently assess cancer 

potency or perform cancer risk assessments. Minimal Risk Levels (MRLs) for noncancer end points (if 

derived) and the end points from which they were derived are indicated and discussed. 

Limitations to existing scientific literature that prevent a satisfactory evaluation of the relevance to public 

health are identified in the Chapter 3 Data Needs section. 

Interpretation of Minimal Risk Levels 

Where sufficient toxicologic information is available, ATSDR has derived MRLs for inhalation and oral 

routes of entry at each duration of exposure (acute, intermediate, and chronic). These MRLs are not 

meant to support regulatory action, but to acquaint health professionals with exposure levels at which 

adverse health effects are not expected to occur in humans. 
 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL B-2 

APPENDIX B 

MRLs should help physicians and public health officials determine the safety of a community living near 

a chemical emission, given the concentration of a contaminant in air or the estimated daily dose in water. 

MRLs are based largely on toxicological studies in animals and on reports of human occupational 

exposure. 

MRL users should be familiar with the toxicologic information on which the number is based. Chapter 2, 

"Relevance to Public Health," contains basic information known about the substance. Other sections such 

as Chapter 3 Section 3.9, "Interactions with Other Substances,” and Section 3.10, "Populations that are 

Unusually Susceptible" provide important supplemental information. 

MRL users should also understand the MRL derivation methodology. MRLs are derived using a 

modified version of the risk assessment methodology that the Environmental Protection Agency (EPA) 

provides (Barnes and Dourson 1988) to determine reference doses (RfDs) for lifetime exposure. 

To derive an MRL, ATSDR generally selects the most sensitive end point which, in its best judgement, 

represents the most sensitive human health effect for a given exposure route and duration. ATSDR 

cannot make this judgement or derive an MRL unless information (quantitative or qualitative) is available 

for all potential systemic, neurological, and developmental effects. If this information and reliable 

quantitative data on the chosen end point are available, ATSDR derives an MRL using the most sensitive 

species (when information from multiple species is available) with the highest no-observed-adverse-effect 

level (NOAEL) that does not exceed any adverse effect levels. When a NOAEL is not available, a 

lowest-observed-adverse-effect level (LOAEL) can be used to derive an MRL, and an uncertainty factor 

(UF) of 10 must be employed. Additional uncertainty factors of 10 must be used both for human 

variability to protect sensitive subpopulations (people who are most susceptible to the health effects 

caused by the substance) and for interspecies variability (extrapolation from animals to humans). In 

deriving an MRL, these individual uncertainty factors are multiplied together. The product is then 

divided into the inhalation concentration or oral dosage selected from the study. Uncertainty factors used 

in developing a substance-specific MRL are provided in the footnotes of the levels of significant exposure 

(LSE) tables. 

Chapter 3 

Health Effects 

Tables and Figures for Levels of Significant Exposure (LSE) 

Tables and figures are used to summarize health effects and illustrate graphically levels of exposure 

associated with those effects. These levels cover health effects observed at increasing dose 

concentrations and durations, differences in response by species, MRLs to humans for noncancer end 

points, and EPA's estimated range associated with an upper- bound individual lifetime cancer risk of 1 in 

10,000 to 1 in 10,000,000. Use the LSE tables and figures for a quick review of the health effects and to 

locate data for a specific exposure scenario. The LSE tables and figures should always be used in 

conjunction with the text. All entries in these tables and figures represent studies that provide reliable, 

quantitative estimates of NOAELs, LOAELs, or Cancer Effect Levels (CELs). 

The legends presented below demonstrate the application of these tables and figures. Representative 

examples of LSE Table 3-1 and Figure 3-1 are shown. The numbers in the left column of the legends 

correspond to the numbers in the example table and figure. 
 

 

 

 

 

 

ETHYLENE GLYCOL B-3 

APPENDIX B 

LEGEND 

See Sample LSE Table 3-1 (page B-6) 

(1)	 Route of Exposure. One of the first considerations when reviewing the toxicity of a substance 

using these tables and figures should be the relevant and appropriate route of exposure. Typically 

when sufficient data exist, three LSE tables and two LSE figures are presented in the document. 

The three LSE tables present data on the three principal routes of exposure, i.e., inhalation, oral, 

and dermal (LSE Tables 3-1, 3-2, and 3-3, respectively). LSE figures are limited to the inhalation 

(LSE Figure 3-1) and oral (LSE Figure 3-2) routes. Not all substances will have data on each 

route of exposure and will not, therefore, have all five of the tables and figures. 

(2)	 Exposure Period. Three exposure periods—acute (less than 15 days), intermediate (15– 

364 days), and chronic (365 days or more)—are presented within each relevant route of exposure. 

In this example, an inhalation study of intermediate exposure duration is reported. For quick 

reference to health effects occurring from a known length of exposure, locate the applicable 

exposure period within the LSE table and figure. 

(3)	 Health Effect. The major categories of health effects included in LSE tables and figures are 

death, systemic, immunological, neurological, developmental, reproductive, and cancer. 

NOAELs and LOAELs can be reported in the tables and figures for all effects but cancer. 

Systemic effects are further defined in the "System" column of the LSE table (see key number 

18). 

(4)	 Key to Figure. Each key number in the LSE table links study information to one or more data 

points using the same key number in the corresponding LSE figure. In this example, the study 

represented by key number 18 has been used to derive a NOAEL and a Less Serious LOAEL 

(also see the two "18r" data points in sample Figure 3-1). 

(5)	 Species. The test species, whether animal or human, are identified in this column. Chapter 2, 

"Relevance to Public Health," covers the relevance of animal data to human toxicity and 

Section 3.4, "Toxicokinetics," contains any available information on comparative toxicokinetics. 

Although NOAELs and LOAELs are species specific, the levels are extrapolated to equivalent 

human doses to derive an MRL. 

(6)	 Exposure Frequency/Duration. The duration of the study and the weekly and daily exposure 

regimens are provided in this column. This permits comparison of NOAELs and LOAELs from 

different studies. In this case (key number 18), rats were exposed to “Chemical x” via inhalation 

for 6 hours/day, 5 days/week, for 13 weeks. For a more complete review of the dosing regimen, 

refer to the appropriate sections of the text or the original reference paper (i.e., Nitschke et al. 

1981). 

(7)	 System. This column further defines the systemic effects. These systems include respiratory, 

cardiovascular, gastrointestinal, hematological, musculoskeletal, hepatic, renal, and 

dermal/ocular. "Other" refers to any systemic effect (e.g., a decrease in body weight) not covered 

in these systems. In the example of key number 18, one systemic effect (respiratory) was 

investigated. 

(8)	 NOAEL. A NOAEL is the highest exposure level at which no harmful effects were seen in the 

organ system studied. Key number 18 reports a NOAEL of 3 ppm for the respiratory system, 

which was used to derive an intermediate exposure, inhalation MRL of 0.005 ppm (see 

footnote "b"). 
 

 

 

 

 

 

 

 

 

 

 

 

 

ETHYLENE GLYCOL B-4 

APPENDIX B 

(9)	 LOAEL. A LOAEL is the lowest dose used in the study that caused a harmful health effect. 

LOAELs have been classified into "Less Serious" and "Serious" effects. These distinctions help 

readers identify the levels of exposure at which adverse health effects first appear and the 

gradation of effects with increasing dose. A brief description of the specific end point used to 

quantify the adverse effect accompanies the LOAEL. The respiratory effect reported in key 

number 18 (hyperplasia) is a Less Serious LOAEL of 10 ppm. MRLs are not derived from 

Serious LOAELs. 

(10)	 Reference. The complete reference citation is given in Chapter 9 of the profile. 

(11)	 CEL. A CEL is the lowest exposure level associated with the onset of carcinogenesis in 

experimental or epidemiologic studies. CELs are always considered serious effects. The LSE 

tables and figures do not contain NOAELs for cancer, but the text may report doses not causing 

measurable cancer increases. 

(12)	 Footnotes. Explanations of abbreviations or reference notes for data in the LSE tables are found 

in the footnotes. Footnote "b" indicates that the NOAEL of 3 ppm in key number 18 was used to 

derive an MRL of 0.005 ppm. 

LEGEND 

See Sample Figure 3-1 (page B-7) 

LSE figures graphically illustrate the data presented in the corresponding LSE tables. Figures help the 

reader quickly compare health effects according to exposure concentrations for particular exposure 

periods. 

(13)	 Exposure Period. The same exposure periods appear as in the LSE table. In this example, health 

effects observed within the acute and intermediate exposure periods are illustrated. 

(14)	 Health Effect. These are the categories of health effects for which reliable quantitative data 

exists. The same health effects appear in the LSE table. 

(15)	 Levels of Exposure. Concentrations or doses for each health effect in the LSE tables are 

graphically displayed in the LSE figures. Exposure concentration or dose is measured on the log 

scale "y" axis. Inhalation exposure is reported in mg/m3 or ppm and oral exposure is reported in 

mg/kg/day. 

(16)	 NOAEL. In this example, the open circle designated 18r identifies a NOAEL critical end point in 

the rat upon which an intermediate inhalation exposure MRL is based. The key number 18 

corresponds to the entry in the LSE table. The dashed descending arrow indicates the 

extrapolation from the exposure level of 3 ppm (see entry 18 in the table) to the MRL of 

0.005 ppm (see footnote "b" in the LSE table). 

(17)	 CEL. Key number 38m is one of three studies for which CELs were derived. The diamond 

symbol refers to a CEL for the test species-mouse. The number 38 corresponds to the entry in the 

LSE table. 
 

 

ETHYLENE GLYCOL B-5 

APPENDIX B 

(18)	 Estimated Upper-Bound Human Cancer Risk Levels. This is the range associated with the upperbound for lifetime cancer risk of 1 in 10,000 to 1 in 10,000,000. These risk levels are derived 

from the EPA's Human Health Assessment Group's upper-bound estimates of the slope of the 

cancer dose response curve at low dose levels (q1*). 

(19)	 Key to LSE Figure. The Key explains the abbreviations and symbols used in the figure. 
SAMPLE

1 → Table 3-1. Levels of Significant Exposure to [Chemical x] – Inhalation 

LOAEL (effect) Exposure 

Key to frequency/ NOAEL Less serious Serious (ppm) figurea Species duration System (ppm) (ppm) Re

2 3 4 

→ INTERMEDIATE EXPOSURE 

5 6 7 8 9 10 

→ Systemic ↓ ↓ ↓ ↓ ↓ ↓

18 Rat 13 wk Resp 3b 10 (hyperplasia) 

→ 5 d/wk Nit

6 hr/d 

CHRONIC EXPOSURE 

Cancer 11 

↓

38 Rat 18 mo 20 (CEL, multiple Wo

5 d/wk organs) 7 hr/d 

39 Rat 89–104 wk 10 (CEL, lung tumors, NT

5 d/wk nasal tumors) 6 hr/d 

40 Mouse 79–103 wk 10 (CEL, lung tumors, NT

5 d/wk hemangiosarcomas) 6 hr/d 

12 → a The number corresponds to entries in Figure 3-1. b Used to derive an intermediate inhalation Minimal Risk Level (MRL) of 5x10-3 ppm; dose adjusted for intermittent ex

by an uncertainty factor of 100 (10 for extrapolation from animal to humans, 10 for human variability). 

ETHYLENE GLYCOL B-8 

APPENDIX B 

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ETYLENE GLYCOL C-1 

APPENDIX C. ACRONYMS, ABBREVIATIONS, AND SYMBOLS 

ACGIH American Conference of Governmental Industrial Hygienists 

ACOEM American College of Occupational and Environmental Medicine 

ADI acceptable daily intake 

ADME absorption, distribution, metabolism, and excretion 

AED atomic emission detection 

AFID alkali flame ionization detector 

AFOSH Air Force Office of Safety and Health 

ALT alanine aminotransferase 

AML acute myeloid leukemia 

AOAC Association of Official Analytical Chemists 

AOEC Association of Occupational and Environmental Clinics 

AP alkaline phosphatase 

APHA American Public Health Association 

AST aspartate aminotransferase 

atm atmosphere 

ATSDR Agency for Toxic Substances and Disease Registry 

AWQC Ambient Water Quality Criteria 

BAT best available technology 

BCF bioconcentration factor 

BEI Biological Exposure Index 

BMD/C benchmark dose or benchmark concentration 

BMDX dose that produces a X% change in response rate of an adverse effect 

BMDLX 95% lower confidence limit on the BMDX 

BMDS Benchmark Dose Software 

BMR benchmark response 

BSC Board of Scientific Counselors 

C centigrade 

CAA Clean Air Act 

CAG Cancer Assessment Group of the U.S. Environmental Protection Agency 

CAS Chemical Abstract Services 

CDC Centers for Disease Control and Prevention 

CEL cancer effect level 

CELDS Computer-Environmental Legislative Data System 

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act 

CFR Code of Federal Regulations 

Ci curie 

CI confidence interval 

CL ceiling limit value 

CLP Contract Laboratory Program 

cm centimeter 

CML chronic myeloid leukemia 

CPSC Consumer Products Safety Commission 

CWA Clean Water Act 

DHEW Department of Health, Education, and Welfare 

DHHS Department of Health and Human Services 

DNA deoxyribonucleic acid 

DOD Department of Defense 

DOE Department of Energy 

DOL Department of Labor 
 

 

ETYLENE GLYCOL C-2 

APPENDIX C 

DOT Department of Transportation 

DOT/UN/ Department of Transportation/United Nations/ 

NA/IMDG North America/Intergovernmental Maritime Dangerous Goods Code 

DWEL drinking water exposure level 

ECD electron capture detection 

ECG/EKG electrocardiogram 

EEG electroencephalogram 

EEGL Emergency Exposure Guidance Level 

EPA Environmental Protection Agency 

F Fahrenheit 

F1 first-filial generation 

FAO Food and Agricultural Organization of the United Nations 

FDA Food and Drug Administration 

FEMA Federal Emergency Management Agency 

FIFRA Federal Insecticide, Fungicide, and Rodenticide Act 

FPD flame photometric detection 

fpm feet per minute 

FR Federal Register 

FSH follicle stimulating hormone 

g gram 

GC gas chromatography 

gd gestational day 

GLC gas liquid chromatography 

GPC gel permeation chromatography 

HPLC high-performance liquid chromatography 

HRGC high resolution gas chromatography 

HSDB Hazardous Substance Data Bank 

IARC International Agency for Research on Cancer 

IDLH immediately dangerous to life and health 

ILO International Labor Organization 

IRIS Integrated Risk Information System 

Kd adsorption ratio 

kg kilogram 

kkg metric ton 

Koc organic carbon partition coefficient 

Kow octanol-water partition coefficient 

L liter 

LC liquid chromatography 

LC50 lethal concentration, 50% kill 

LCLo lethal concentration, low 

LD50 lethal dose, 50% kill 

LDLo lethal dose, low 

LDH lactic dehydrogenase 

LH luteinizing hormone 

LOAEL lowest-observed-adverse-effect level 

LSE Levels of Significant Exposure 

LT50 lethal time, 50% kill 

m meter 

MA trans,trans-muconic acid 

MAL maximum allowable level 

mCi millicurie 
 

ETYLENE GLYCOL C-3 

APPENDIX C 

MCL maximum contaminant level 

MCLG maximum contaminant level goal 

MF modifying factor 

MFO mixed function oxidase 

mg milligram 

mL milliliter 

mm millimeter 

mmHg millimeters of mercury 

mmol millimole 

mppcf millions of particles per cubic foot 

MRL Minimal Risk Level 

MS mass spectrometry 

NAAQS National Ambient Air Quality Standard 

NAS National Academy of Science 

NATICH National Air Toxics Information Clearinghouse 

NATO North Atlantic Treaty Organization 

NCE normochromatic erythrocytes 

NCEH National Center for Environmental Health 

NCI National Cancer Institute 

ND not detected 

NFPA National Fire Protection Association 

ng nanogram 

NHANES National Health and Nutrition Examination Survey 

NIEHS National Institute of Environmental Health Sciences 

NIOSH National Institute for Occupational Safety and Health 

NIOSHTIC NIOSH's Computerized Information Retrieval System 

NLM National Library of Medicine 

nm nanometer 

nmol nanomole 

NOAEL no-observed-adverse-effect level 

NOES National Occupational Exposure Survey 

NOHS National Occupational Hazard Survey 

NPD nitrogen phosphorus detection 

NPDES National Pollutant Discharge Elimination System 

NPL National Priorities List 

NR not reported 

NRC National Research Council 

NS not specified 

NSPS New Source Performance Standards 

NTIS National Technical Information Service 

NTP National Toxicology Program 

ODW Office of Drinking Water, EPA 

OERR Office of Emergency and Remedial Response, EPA 

OHM/TADS Oil and Hazardous Materials/Technical Assistance Data System 

OPP Office of Pesticide Programs, EPA 

OPPT Office of Pollution Prevention and Toxics, EPA 

OPPTS Office of Prevention, Pesticides and Toxic Substances, EPA 

OR odds ratio 

OSHA Occupational Safety and Health Administration 

OSW Office of Solid Waste, EPA 

OTS Office of Toxic Substances 
 

 

ETYLENE GLYCOL C-4 

APPENDIX C 

OW Office of Water 

OWRS Office of Water Regulations and Standards, EPA 

PAH polycyclic aromatic hydrocarbon 

PBPD physiologically based pharmacodynamic 

PBPK physiologically based pharmacokinetic 

PCE polychromatic erythrocytes 

PEL permissible exposure limit 

pg picogram 

PHS Public Health Service 

PID photo ionization detector 

pmol picomole 

PMR proportionate mortality ratio 

ppb parts per billion 

ppm parts per million 

ppt parts per trillion 

PSNS pretreatment standards for new sources 

RBC red blood cell 

REL recommended exposure level/limit 

RfC reference concentration 

RfD reference dose 

RNA ribonucleic acid 

RQ reportable quantity 

RTECS Registry of Toxic Effects of Chemical Substances 

SARA Superfund Amendments and Reauthorization Act 

SCE sister chromatid exchange 

SGOT serum glutamic oxaloacetic transaminase 

SGPT serum glutamic pyruvic transaminase 

SIC standard industrial classification 

SIM selected ion monitoring 

SMCL secondary maximum contaminant level 

SMR standardized mortality ratio 

SNARL suggested no adverse response level 

SPEGL Short-Term Public Emergency Guidance Level 

STEL short term exposure limit 

STORET Storage and Retrieval 

TD50 toxic dose, 50% specific toxic effect 

TLV threshold limit value 

TOC total organic carbon 

TPQ threshold planning quantity 

TRI Toxics Release Inventory 

TSCA Toxic Substances Control Act 

TWA time-weighted average 

UF uncertainty factor 

U.S. United States 

USDA United States Department of Agriculture 

USGS United States Geological Survey 

VOC volatile organic compound 

WBC white blood cell 

WHO World Health Organization 
 

ETYLENE GLYCOL C-5 

APPENDIX C 

> greater than ≥ greater than or equal to 

= equal to 

< less than ≤ less than or equal to 

% percent α alpha β beta γ gamma δ delta 

μm micrometer 

μg microgram q1

* cancer slope factor 

– negative 

+ positive 

(+) weakly positive result 

(–) weakly negative result 
ETYLENE GLYCOL C-6 

APPENDIX C 

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ETYLENE GLYCOL D-1 

APPENDIX D. INDEX
 

absorbed dose............................................................................................................................................148
 

adipose tissue ............................................................................................................................................212
 

adrenals ............................................................................................................................. 22, 31, 46, 97, 143
 

adsorbed............................................................................................................................................ 204, 213
 

adsorption.......................................................................................................................................... 194, 212
 

aerobic....................................................................................................................... 186, 187, 195, 196, 204
 

alanine aminotransferase (see ALT) ...........................................................................................................91
 

ALT (see alanine aminotransferase)...........................................................................................................91
 

ambient air ........................................................................................................................ 197, 198, 200, 205
 

anaerobic................................................................................................................................... 195, 196, 204
 

anion gap..................................................................................................................... 99, 139, 150, 151, 167
 

antiestrogenic ............................................................................................................................................143
 

aspartate aminotransferase (see AST).........................................................................................................91
 

AST (see aspartate aminotransferase).........................................................................................................91
 

bioavailability ...........................................................................................................................................204
 

bioconcentration factor .............................................................................................................................194
 

biodegradation................................................................................................... 186, 187, 194, 195, 196, 204
 

biomarker .......................................................................................... 148, 149, 151, 166, 167, 168, 207, 215
 

blood cell count...........................................................................................................................................46
 

body weight effects................................................................................................................. 41, 51, 98, 112
 

breast milk................................................................................................................. 4, 9, 147, 199, 201, 202
 

cancer.................................................................................................. 3, 12, 21, 49, 115, 144, 158, 162, 166
 

carcinogen......................................................................................................................................... 217, 220
 

carcinogenic .................................................................................................................................... 12, 16, 40
 

carcinogenicity.................................................................................................................. 111, 158, 162, 217
 

cardiac arrhythmia ......................................................................................................................................87
 

cardiovascular ................................................................................................. 45, 51, 87, 112, 139, 156, 158
 

cardiovascular effects............................................................................................................................ 45, 87
 

clearance ....................................................................................................................... 33, 96, 120, 133, 135
 

cranial nerves .............................................................................................................................. 10, 103, 165
 

death................................................................................ 3, 11, 35, 39, 40, 41, 50, 51, 87, 97, 103, 111, 140
 

deoxyribonucleic acid (see DNA).............................................................................................................115
 

dermal effects...................................................................................................................................... 98, 112
 

developmental effects ................................ 12, 13, 14, 17, 24, 26, 28, 48, 49, 107, 108, 109, 110, 111, 114, 

136, 140, 141, 142, 146, 147, 163, 164, 168, 170, 172
 

DNA (see deoxyribonucleic acid)............................................................................. 115, 116, 140, 147, 148
 

elimination half-time.................................................................................................................................136
 

endocrine................................................................................................... 41, 46, 51, 97, 112, 142, 143, 147
 

endocrine effects ........................................................................................................................... 46, 97, 143
 

erythema......................................................................................................................................................46
 

estrogen receptor.......................................................................................................................................143
 

estrogenic ..................................................................................................................................................143
 

fetal tissue .................................................................................................................................................120
 

fetus............................................................................................................... 11, 23, 120, 138, 144, 146, 160
 

gastrointestinal effects ................................................................................................................................88
 

general population........................................................................................... 9, 39, 166, 199, 200, 202, 205
 

genotoxic............................................................................................................................................. 40, 115
 

genotoxicity............................................................................................................................... 115, 147, 162
 

groundwater ...................................................................... 2, 9, 166, 193, 194, 196, 198, 199, 202, 204, 205
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ETYLENE GLYCOL D-2 

APPENDIX D 

half-life........................................................................ 10, 123, 127, 128, 138, 148, 149, 166, 195, 196, 204
 

hematological effects ...................................................................................................................... 23, 45, 89
 

hematopoietic........................................................................................................................................ 11, 23
 

hepatic effects ............................................................................................................................... 12, 90, 112
 

hydrolysis.................................................................................................................................. 179, 183, 196
 

hydroxyl radical ................................................................................................................................ 195, 204
 

immunological ................................................................................................ 11, 39, 46, 100, 101, 112, 164
 

immunological effects.................................................................................................................................46
 

Kow .................................................................................................................................................... 177, 194
 

LD50............................................................................................................................................... 50, 51, 164
 

lymphoreticular................................................................................................... 11, 100, 101, 112, 158, 164
 

metabolic acidosis...................................................... 10, 11, 12, 14, 99, 100, 103, 138, 139, 140, 141, 145, 

146, 147, 149, 150, 154, 155, 167, 171, 172
 

metabolic effects ........................................................................................................................... 41, 99, 112
 

milk ...........................................................................................................................................................212
 

musculoskeletal effects...............................................................................................................................90
 

neonatal..................................................................................................................................... 147, 202, 206
 

neurobehavioral................................................................................. 11, 16, 20, 47, 103, 143, 159, 160, 165
 

neurological effects............................................................................... 46, 47, 102, 104, 114, 151, 158, 165
 

neurophysiological....................................................................................................................................102
 

ocular effects................................................................................................................................. 46, 98, 112
 

odds ratio.....................................................................................................................................................49
 

osmolal gap ................................................................................................................. 99, 138, 145, 150, 151
 

oxidative phosphorylation.........................................................................................................................140
 

partition coefficients .................................................................................................................................133
 

PBPK model.................................................................................. 26, 29, 130, 131, 133, 137, 147, 170, 173
 

pharmacodynamic.....................................................................................................................................130
 

pharmacokinetic............................................................................................ 14, 28, 130, 131, 132, 136, 144
 

photolysis.......................................................................................................................................... 195, 196
 

placenta ....................................................................................................... 26, 120, 137, 138, 142, 170, 172
 

rate constant .............................................................................................................................. 133, 195, 197
 

renal effects......................................................................... 12, 14, 15, 20, 36, 92, 93, 94, 97, 112, 151, 156
 

reproductive effects..................................................................................................... 47, 104, 106, 114, 163
 

respiratory effects............................................................................................................................ 41, 51, 87
 

skeletal malformations............................................ 12, 13, 17, 24, 25, 27, 48, 107, 108, 109, 110, 146, 163
 

solubility ................................................................................................................................... 126, 194, 204
 

spermatogonia...........................................................................................................................................106
 

spermatozoa ..............................................................................................................................................106
 

systemic effects....................................................................... 11, 16, 18, 19, 20, 41, 51, 112, 158, 159, 160
 

T3.................................................................................................................................................. 42, 52, 113
 

thyroid..................................................................................................................................... 31, 46, 97, 143
 

toxicokinetic.................................................. 14, 39, 120, 136, 138, 147, 162, 163, 167, 168, 169, 170, 172
 

vapor phase ............................................................................................................................... 194, 203, 204
 

vapor pressure ...........................................................................................................................................194
 

volatilization ..................................................................................................................................... 194, 204
 

weanling......................................................................................................................................................30