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Ethylene Glycol NTP-CERHR Monograph on the Potential Human Reproductive and Developmental Effects of Ethylene Glycol January 2004 NIH Publication No. 04-4481 Table of Contents Preface .............................................................................................................................................v Introduction .................................................................................................................................... vi NTP Brief on Ethylene Glycol .........................................................................................................1 References ........................................................................................................................................4 Appendix I. NTP-CERHR Ethylene Glycol / Propylene Glycol Expert Panel Preface ..............................................................................................................................I-1 Expert Panel ......................................................................................................................I-2 Appendix II. Expert Panel Report on Ethylene Glycol ............................................................... II-i Table of Contents ........................................................................................................... II-iii Abbreviations ...................................................................................................................II-v List of Tables ................................................................................................................ II-viii List of Figures ..................................................................................................................II-x Preface ........................................................................................................................... II-xi Chemistry, Usage and Exposure ......................................................................................II-1 General Toxicological and Biological Effects ...............................................................II-11 Developmental Toxicity Data ........................................................................................II-62 Reproductive Toxicity Data .........................................................................................II-106 Summaries, Conclusions and Critical Data Needs .....................................................II-116 References ...................................................................................................................II-121 Appendix III. Public Comments on Ethylene Glycol Expert Panel Report American Chemistry Council ........................................................................................ III-1 iii [This page intentionally left blank] iv Preface The National Toxicology Program (NTP) the chemical is hazardous to humans. The panel established the NTP Center for the Evaluation also identifies areas of uncertainty and where of Risks to Human Reproduction (CERHR) additional data are needed. The CERHR expert in 1998. The CERHR is a publicly accessible panels use explicit guidelines to evaluate the resource for information about adverse repro- scientific literature and prepare the expert panel ductive and/or developmental health effects reports. Expert panel reports are made public associated with exposure to environmental and comments are solicited. and/or occupational chemicals. The CERHR is located at the National Institute of Envi- Next, the CERHR prepares the NTP-CERHR ronmental Health Sciences (NIEHS) of the monograph. The NTP-CERHR monograph National Institutes of Health and Dr. Michael includes the NTP brief on the chemical eval- Shelby is the director.1 uated, the expert panel report, and all public comments. The goal of the NTP brief is to pro- The CERHR broadly solicits nominations of vide the public, as well as government health, chemicals for evaluation from the public and regulatory, and research agencies, with the private sectors. The CERHR follows a formal NTP’s interpretation of the potential for the process for review and evaluation of nominated chemical to adversely affect human reproduc- chemicals that includes multiple opportunities tive health or children’s health. The NTP- for public comment. Chemicals are selected for CERHR monograph is made publicly available evaluation based upon several factors including electronically on the CERHR web site and in the following: hard copy or CD-ROM from the CERHR. • potential for human exposure from use and occurrence in the environment 1Information about the CERHR is available on the • extent of public concern web at <http://cerhr.niehs.nih.gov> or by contact- • production volume ing the director: • availability of scientific evidence for repro- NIEHS, P.O. Box 12233, MD EC-32, ductive and/or developmental toxicity. Research Triangle Park, NC 27709 919-541-3455 [phone] The CERHR convenes a scientific expert panel 919-316-4511 [fax] that meets in a public forum to review, discuss, [email protected] [email] and evaluate the scientific literature on the Information about the NTP is available on the web selected chemical. Public comment is invited at <http://ntp-server.niehs.nih.gov> or by contact- prior to and during the meeting. The expert panel ing the NTP Office of Liaison and Scientific Re- produces a report on the chemical’s reproduc- view at the NIEHS: tive and developmental toxicities and provides [email protected] [email] its opinion of the degree to which exposure to 919-541-0530 [phone] v Introduction In 1999, the CERHR Core Committee, an advi- comments throughout the evaluation process. sory committee composed of representatives from NTP member agencies, recommended TheTP N has prepared an NTP-CERHR ethylene glycol and propylene glycol for expert monograph for ethylene glycol. This monograph panel review. includes the NTP brief on ethylene glycol, a list of expert panel members (Appendix I), This chemical was selected because: the expert panel report on ethylene glycol (a) its i a high production volume chemical; (Appendix II), and all public comments received (b) theres i widespread human exposure; on the expert panel report on ethylene glycol (c) the toxicology database on ethylene (Appendix III). The NTP-CERHR monograph glycol includes recent data on its mech- is intended to serve as a single, collective source anism of action and occupational expo- of information on the potential for ethylene sure information. glycol to adversely affect human reproduction Propylene glycol is the subject of a separate or development. Those interested in reading this monograph. monograph may include individuals, members of public interest groups, and staff of health and Ethylene glycol is used as a chemical inter- regulatory agencies. mediate in the production of polyester compounds. It also is found in automotive anti- The NTP brief included within this monograph freeze, industrial coolants, hydraulic fluids, and presents the NTP’s interpretation of the windshield deicer fluids. potential for ethylene glycol exposure to cause adverse reproductive or developmental effects As part of the evaluation of ethylene glycol, in people. It is based on information about the CERHR convened a panel of scientific ethylene glycol provided in the expert panel experts (Appendix I) to review, discuss, and report, the public comments, and additional evaluate the scientific evidence on the poten- scientific information available since the expert tial reproductive and developmental toxicities panel meeting. The NTP brief is intended to of the chemical. There was a public meeting of provide clear, balanced, scientifically sound the CERHR Ethylene Glycol / Propylene Gly- information on the potential for ethylene glycol col (EG/PG) Expert Panel on February 11-13, exposures to result in adverse effects on human 2003. The CERHR received numerous public reproduction and development. vi NTP Brief on Ethylene Glycol NTP Brief NTP What is Ethylene Glycol? antifreeze solutions and brake fluid. No infor- Ethylene Glycol (EG) is a small, hydroxy-sub- mation is available on EG levels in drinking or stituted hydrocarbon with the chemical formula bathing water. C2H6O2 and the structure shown in Figure 1. The general public also may be exposed to EG Figure 1. Chemical structure of EG by inhalation. However, very little EG is ex- pected to be present in outdoor air, with the HO CH CH OH 2 2 possible exception of point source emissions EG is used as a chemical intermediate in the pro- such as EG production facilities or deicing ac- duction of polyester compounds. It is also found tivities. Therefore, significant exposure through in automotive anti-freeze, industrial coolants, outdoor air is not expected for the majority of hydraulic fluids, and windshield deicer fluids. the general population. EG can be manufactured by one of four meth- Health Canada estimated a worst-case-scenario ods. It can be produced by oxidation of ethyl- of human EG exposure (dermal, ingestion, ene to ethylene oxide, followed by hydration; and inhalation) in the range of 22 to 88 µg/kg by acetoxylation to form mixed mono- and di- bw/day for persons living next to an industrial acetates that are then hydrolyzed to form EG point source. Because human exposure data are and acetic acid; from carbon monoxide and hy- limited, this estimate was based on assumptions drogen derived from coal gassification; or by of higher rather than lower exposures. Thus, catalytic oxidation of ethylene to
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