Ethylene Oxide
Full Profile
General Information
Ethylene oxide is a colourless gas with a characteristic sweet ether-like odour.[2,3] It is highly flammable and dissolves easily in water, alcohol, and most organic solvents.[3] Produced since the early 1900’s, ethylene oxide has been used as a chemical intermediate and as a sterilizing agent.[4]
Ethylene oxide may also be referred to as oxirane and EtO.[4] There are numerous other synonyms and product names; see HSDB for more information.[5]
Ethylene oxide has recently been classified by IARC as Group 1, carcinogenic to humans, with sufficient evidence of carcinogenicity in humans.[4] Initially classified as Group 2A, with links to lymphatic and hematopoietic cancers, the upgrade to a known carcinogen is based on current epidemiological studies of workers exposed to EtO as a sterilizing agent and during chemical synthesis and production.[2] A recent IARC review reaffirmed this classification, with strong evidence for lymphoid and breast cancers.[22] Mechanistic studies support the Group 1 designation, as EtO is a potent alkylating agent, frequently showing genotoxic effects.[6] EtO’s effective sterilizing properties and its carcinogenicity both arise from its capacity to damage DNA.[2]
Ethylene oxide causes irritation of the eyes, skin and respiratory system, as well as central nervous system effects.[3] With chronic exposure, neurological effects including memory loss, peripheral neuropathies and impaired coordination have been reported.[3] Asthmatic reactions can occur in individuals sensitized to EtO.[6] There is limited evidence that ethylene oxide exposure may be associated with increased risk of miscarriage.[3]
How did CAREX choose this agent for review?
Regulations and Guidelines
Occupational Exposure Limits (OEL)
| Canadian Jurisdictions | OEL (ppm) |
|---|---|
| Canada Labour Code | 1 |
| BC | 0.1 [rep] 1 [stel, rep] |
| AB, MB, QC, NL, PE, NB, NS | 1 |
| SK | 1 2 [stel] |
| ON | 1 10 [stel] |
| Other Jurisdiction | OEL (ppm) |
| ACGIH 2011 TLV | 1 |
Canadian Environmental Guidelines
| Jurisdiction | Limit | Year |
|---|---|---|
| Food Additives Permitted for Use | Code: X (Miscellaneous agents) |
2006[9] |
| Cosmetic Ingredients Hotlist | Not Permitted | 2011[15] |
Canadian Agencies/Organizations
| Agency | Designation/Position | Year |
|---|---|---|
| Health Canada | DSL – low priority substance (already risk managed)* | 2006[10] |
| CEPA | Schedule 1, paragraph ‘c’ | 1999[11] |
| Challenge to Industry* | Batch 1 (Health) | 2010[16] |
Main Uses
Ethylene oxide is used as a chemical intermediate, primarily for the production of ethylene glycol (antifreeze).[2] Other chemicals produced using EtO include glycol ethers, ethanolamines, alkanolamines, polyglycols, ethoxylates and choline chloride.[12]
Smaller amounts of EtO are used as sterilizing agents, disinfectants, fumigants or insecticides.[2] Medical facilities (hospitals, medical and dental clinics) and manufacturers of sterile medical supplies account for the majority of its use as a sterilant.[2] In Canada, approximately 120 healthcare facilities use ethylene oxide as a sterilant.[23] Information on use of ethylene oxide for sterilization in smaller clinics, such as veterinary and dental clinics, is currently unavailable.[24]
Other applications for use as a sterilant include heat sensitive materials such as furs, furniture, beehives, cosmetics, drugs and tobacco,[2] and in the publication and wood products industries.[6]
EtO is used as a fumigant to control bacteria in spices and natural seasonings and to control insects in stored products.[6]
Canadian Production and Trade
In 2004, ethylene oxide was produced by Dow Chemical Canada. (2 locations in AB), Shell Canada (AB), Alberta & Orient Glycol (AB).[12]
Production and Trade
| Activity | Quantity | Year |
|---|---|---|
| Canadian Production | 108,400 t | 2004[4] |
| Export: Mainly to Argentina | 68 t of ‘oxirane (ethylene oxide)’ | 2010[17] |
| Import: Mainly from US, Korea | 7 t of 'oxirane (ethylene oxide)' | 2010[17] |
Occupational Exposures
Inhalation is the most important route of occupational exposure to ethylene oxide.[3] Although the majority of ethylene oxide is used for the production of chemicals, most occupational exposure occurs through its use in sterilization, particularly of medical equipment.[2,25] The highest exposures have been measured in facilities using EtO as a sterilant or fumigant, including hospitals, health care facilities and spice manufacturers.[18] Workers may be exposed during the changing of ethylene oxide gas cylinders; from leaking equipment; from improper ventilation at the sterilizer door, discharge line, aerators and in the general room; during removal and transfer of items from the sterilizer to an aerator; and from incomplete aeration of items.[24] Ethylene oxide is registered in 9 products in the Drug Products Database of Health Canada for use as a disinfectant.[19] Some studies have shown that exposures during sterilization procedures can be effectively controlled by industrial hygiene measures.[2] Current average concentrations of ethylene oxide in hospitals and production facilities have decreased substantially from historical levels, to <2 mg/m3 in western Europe and North America.[2]
Potential exists for exposure to EtO during the production of industrial chemicals. These processes are usually automated and contained in closed systems, however, which minimizes exposure.[18] Exposures in the chemical industry occur mainly during loading and unloading of transport tanks, product sampling, and equipment maintenance and repair.[26]
Environmental Exposures
There is limited data in Canada measuring the general population’s exposure to ethylene oxide, but the most important route of exposure is inhalation.[6] In one national study of 50 ambient air samples (24 hour) taken in randomly selected residential areas, 94% of the samples were below the detection limit.[6] The same study, looking at indoor air, reported 98% of samples below the limit of detection.[6]
Sources of environmental exposure mainly originate from products that have been sterilized with the compound, including medical products, foods, clothing, cosmetics, and beekeeping equipment.[2] A minor source of exposure to ethylene oxide is from gasoline combustion and cigarette smoke (either residue from fumigation of tobacco, or as a combustion by-product).[3,6]
Data on ethylene oxide levels in water, soil, sediment and groundwater in Canada were not identified.[6]
Searches of environmental and consumer product databases yielded the following results on current potential for exposure to ethylene oxide in Canada:
NPRI and US Household Products Database
| NPRI 2009[20] | ||
|---|---|---|
| Search term: ‘ethylene oxide' | ||
| Category | Quantity | Industry |
| Released into Environment | 2.0 t | Chemical manufacturers and hospitals (9 companies) |
| Disposed of | 9.7 t | |
| Sent to off-site recycling | ||
| US Household Products 2010[21] | ||
| Search Term | Quantity | Product Type |
| ’ethylene oxide’ | 2 | Rust remover and driveway cleaner |
Sources
- Wikimedia Commons Photograph: Ethylene Oxide
- NTP 12th Report on Carcinogens for Ethylene Oxide (2011)
- ATSDR Toxicological Profile for Ethylene oxide (1990)
- IARC Monograph: Volume 97 (2008)
- Hazardous Substances Data Bank (Search term: ‘ethylene oxide’)
- Priority Substances List assessment report (CEPA) for Ethylene oxide (2001)
- Health Canada (2010) Guidelines for Canadian Drinking Water
- Exposure Guidelines for Residential Indoor Air Quality (1987)
- Health Canada (2006) Food Additives Permitted for Use in Canada
- Health Canada’s Prioritization of the DSL (2006)
- CEPA List of Toxic Substances (1999)
- CPI Product Profile, Camford Information Services, Ethylene Oxide (2002)
- Environment Canada: Guidelines for the Reduction of Ethylene Oxide Releases from Sterilization Applications (2005)
- PMRA List of Registered Pesticides
- Health Canada (2011) Cosmetic Ingredient Hotlist
- Government of Canada (2010) Chemicals Management Plan – List of all Challenge Substances
- TradeMap (free subscription required)
- WHO: CICAD No. 54: Ethylene oxide (2003)
- Health Canada Drug Product Database (2009)
- The National Pollutant Release Inventory
- Household Products Database (US)
- IARC Monograph Volume 100: A review of human carcinogens—Part F: Chemical agents and related occupations (2009)
- Environment Canada: Risk Management Strategy for Ethylene Oxide (2003)
- Tilman, A, Schwartzkopf, O, and Rahmat A. ENGO Report on Ethylene Oxide (EO): Responding to Environment Canada Consultations on Ethylene Oxide in Sterilization Applications (2003)
- Grosse, Y et al. Carcinogenicity of 1,3-butadiene, ethylene oxide, vinyl chloride, vinyl fluoride, and vinyl bromide. The Lancet Oncology 2007;8(8):679-680.
- WHO: Concise International Chemical Assessment Document 54: Ethylene Oxide (2003)
