2002 June 29

Ethylene Oxide Chemical Backgrounder


Ethylene oxide (C.A.S. 75-21-8) is a colorless liquefied gas with a sweet odor. It is primarily used as a chemical intermediate for ethylene glycol (59%) and other chemicals such as nonionic surfactants (14%), glycol ethers (6%), ethanolamines (8%), triethylene glycol (2%), and diethylene glycol (6%). It is used as a sterilant and fumigant in the health product and medical fields.

It has been used in flame-retardants and to accelerate the maturing of tobacco leaves. It is also used as a fumigant in spices, packaged cereals, bagged rice, tobacco, clothing and furs in vaults, and valuable packaged documents; as an agricultural fungicide; and as a rocket propellant.

Chemical properties:

Ethylene oxide is an odorless gas at room temperature and normal pressure, but is a liquid with an ether-like odor at 10.4 degrees C at higher pressure. It is completely miscible with water, alcohol, acetone, benzene, ether, and most organic solvents. At room temperature, it is an extremely flammable and reactive gas. Its vapors are inflammable and explosive. It is highly reactive and potentially explosive when heated or in the presence of alkali metal hydroxides and highly active catalytic surfaces. Incomplete combustion releases carbon monoxide. Synonyms for ethylene oxide are dihydrooxirene; dimethylene oxide; epoxyethane; 1,2-epoxyethane; ethene oxide; etO; oxacyclopropane; oxane; oxidoethane; amprolene; anproline; and oxirane.


Health effects:

Ethylene oxide is classified by the Occupational Safety and Health Administration (OSHA) as an occupational carcinogen and as a "de minimis" carcinogen, meaning that the minimum amount of the chemical set by OSHA is considered to be carcinogenic. It is listed on EPA's Toxic Release Inventory (TRI) as a de minimis carcinogen. It is also defined as a substance "which may reasonably be anticipated to be a carcinogen" by the U.S. Department of Health and Human Services' National Toxicology Program's Fifth Annual Report on Carcinogens.

Ethylene oxide is linked to peritoneal cancer and leukemia, and also has mutagenic and reproductive effects. Inhalation causes nausea, vomiting, neurological disorders, and even death. Traces of gas in gloves or clothing may cause burns. Residues in vascular catheters can cause thrombophlebitis; in endotracheal tubes, tracheitis.

If inhaled, severe irritation to mucous membranes of respiratory tract may result in pulmonary edema. It may be described as a central nervous system depressant and an irritant. Contact with dilute solution may cause irritation and necrosis of eyes, blistering and necrosis of skin. Excessive exposure may cause irritation of lungs and central nervous system depression.

Repeated exposure can result in reversible peripheral neuropathy. Conjunctivitis, dyspnea, cough, vertigo, nausea and vomiting, abdominal pain, parasystole, arrhythmia, pulmonary edema, and paralysis also can occur.

Exposure Values


U.S. manufacturers of ethylene oxide are: BASF Corp, Parsippany, NJ; Dow Chemical USA, Midland, MI ; Eastman Chemical Co, Kingsport, TN; Hoechst Celanese Corp, Somerville, NJ; Occidental Petroleum Corp, Los Angeles, CA; PD Glycol, Beaumont, TX; Shell Chemical Co, Houston, TX; Sun Company Inc (R&M), Philadelphia, PA; Union Carbide Corp, Danbury, CT ; Texaco Chemical Co, Houston, TX; and Formosa Plastics Corporation U.S.A., Livingston, NJ.


EPA regulates ethylene oxide under the Clean Air Act, Comprehensive Environmental Response, Compensation, and Liability Act (Superfund); Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA); Food, Drug, and Cosmetic Act (FDCA); Resource Conservation and Recovery Act (RCRA); Superfund Amendments and Reauthorization Act (SARA); and Toxic Substances Control Act (TSCA).

The Food and Drug Administration regulates ethylene oxide as a food additive under the FDCA and has proposed maximum residue limits for the compound in drug products and medical devices.

OSHA has established permissible exposure limits for ethylene oxide.

Under Section 313 of the Emergency Planning and Community Right-to-Know Act, releases of more than one pound of ethylene oxide into the air, water, and land must be reported annually and entered into the TRI.

Under Section 302 of the Emergency Planning and Community Right to Know Act of 1986, ethylene oxide is listed as an Extremely Hazardous Substance and has a threshold planning quantity of 10,00 lbs.

Facilities having a threshold quantity of 0,000 lbs of ethylene oxide are subject to the Risk Management Program Rule (RMP), Section 112r of the Clean Air Act. Ethylene oxide has a toxic endpoint of 0.090 mg/L.

National Overview of 1998 Toxics Release Inventory

In 1998, 153 facilities released 640,949 pounds of ethylene oxide. Of those releases, 614,405 pounds were air emissions; 372 pounds were surface water discharges; 22,561 were released by underground injection; 1,751 pounds were released to land; and 1,860 pounds were transferred off-site for disposal. Total emissions for 1998 represented a decrease from 1997 emissions, which totaled 946,189 pounds; from 1996 emissions, which totaled 818,023 pounds;a decrease from 1995 emissions, which totaled 1,002,340 pounds; and a decrease from 1988 (baseline) emissions, which totaled 4,763,073 pounds.

In 1998, 12,732,870 pounds of ethylene oxide waste were managed; 20,146 pounds were recycled on-site; 1,140 pounds were recycled off-site; 13,121 pounds were used for energy recovery on-site; 1,043,190 pounds were used for energy recovery off-site; 10,887,480 pounds were treated on-site; 190,029 pounds were treated off-site; and 587,764 pounds were released on-and off-site.

The 10 states in which the largest amounts of ethylene oxide were released in 1998 were: TX (145,830 pounds); LA (123,752 pounds); GA (60,037 pounds); IL (42,076 pounds); PR (32,960 pounds); SC (28,778 pounds); WV (22,308 pounds); AR (22,300 pounds); MI (16,228 pounds); and NJ (15,613 pounds).

The 10 facilities releasing the largest amounts of ethylene oxide in 1998 were: Shell Chemical Co., Geismar, LA (78,263 pounds); Huntsman Corp. - C4/O&O Plant, Port Neches, TX (42,500 pounds); Celanese Ltd.- Clear Lake Plant, Pasadena, TX (42,226 pounds); Griffith Micro Science Inc., Willowbrook, IL (32,200 pounds); Steri-Tech Inc., Salinas, PR (30,000 pounds); Kendall Co. A Div. Of Tyco Int. Ltd., Augusta, GA (25,522 pounds); Baxter Healthcare Corp., Mountain Home, AR (22,300 pounds); Clariant Corp. Leeds Plant, Carlisle, SC (21,392 pounds); Union Carbide Corp. Institute WV Plant Ops., Institute, WV (18,909 pounds); and C.R. Bard Medical Div., Covington, GA (16,643 pounds).


The NIOSH recommended exposure limits (RELs) are time-weighted average (TWA) concentrations for up to a 10-hour workday during a 40-hour workweek. A short-term exposure limit (STEL) is designated by "ST" preceding the value; unless noted otherwise, the STEL is a 15-minute TWA exposure that should not be exceeded at any time during a workday. A ceiling REL is designated by "C" preceding the value. Any substance that NIOSH considers to be a potential occupational carcinogen is designated by the notation "Ca."

The OSHA permissible exposure limits (PEL) are found in Tables Z-1, Z-2, and Z-3 of the OSHA General Industry Air Contaminants Standard (29 CFR 1910.1000). Unless noted otherwise, PEL are TWA concentrations that must not be exceeded during any 8-hour workshift of a 40-hour workweek. A STEL is designated by "ST" preceding the value and is measured over a 15-minute period unless noted otherwise. OSHA ceiling concentrations (designated by "C" preceding the value) must not be exceeded during any part of the workday; if instantaneous monitoring is not feasible, the ceiling must be assessed as a 15-minute TWA exposure. In addition, there are a number of substances from Table Z-2 (e.g., beryllium, ethylene dibromide, etc.) that have PEL ceiling values that must not be exceeded except for specified excursions. For example, a "5-minute maximum peak in any 2 hours" means that a 5-minute exposure above the ceiling value, but never above the maximum peak, is allowed in any 2 hours during an 8-hour workday.

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