Ethylene oxide, also called oxirane, is an organic compound with the formula C₂H₄O.
It is a cyclic ether consisting of an alkane with an oxygen atom bonded to two carbon atoms, forming a ring.
This colourless, flammable gas has a faintly sweet odour at room temperature and is the simplest epoxide—a three-membered ring made up of one oxygen atom and two carbon atoms.
What is Ethylene Oxide used for?
Ethylene oxide is used in the production of:
Solvents
Antifreeze
Textiles
Detergents
Adhesives
Polyurethane foam
Pharmaceuticals
Smaller amounts are used in:
Fumigants
Sterilants for spices and cosmetics
Hospital sterilisation of surgical equipment
Ethylene oxide is used in the production of detergents.
In the Environment
Ethylene oxide rapidly breaks down when released into the environment.
As a gas, most is released to the air, where it reacts with water vapour and sunlight and degrades within a few days.
While it can dissolve in water, most evaporates quickly; the remainder is broken down by bacteria or by reacting with water and other chemicals.
When released to soil, most evaporates; some degrades through bacterial action or reaction with water.
Ethylene oxide does not persist long in the environment and is not expected to bioaccumulate in the food chain.
Sources & Routes of Exposure
Sources of Exposure
Industrial sources include uncontrolled emissions or venting with other gases.
Other sources:
Automobile exhaust
Release from commodity-fumigated materials
Use as a steriliser for medical equipment
The general population may be exposed via:
Breathing contaminated air
Smoking or second-hand smoke exposure
Higher-risk occupational groups:
Workers in ethylene oxide manufacturing or processing plants
Sterilisation technicians
Workers involved in fumigation
Routes of Exposure
Inhalation
Main exposure route.
Gas is readily absorbed via the lungs.
Odour is not a reliable warning of hazardous concentrations.
Being heavier than air, it can cause asphyxiation in enclosed or poorly ventilated spaces.
Children may receive a higher dose than adults due to:
Greater lung surface area:body weight ratio
Higher minute volume:weight ratio
Shorter stature (higher exposure near the ground)
Skin/Eye Contact
Concentrated solutions, liquid ethylene oxide, or high vapour levels can cause chemical burns.
Liquefied ethylene oxide may cause frostbite.
High vapour levels may cause corneal burns and cataracts.
Prolonged contact with dilute solutions (e.g., contaminated clothing) can cause irritation and dermatitis.
Children are more vulnerable due to a higher skin surface area:body weight ratio.
Ingestion
Unlikely, as ethylene oxide is a gas at room temperature.
Health Effects
Acute Effects
High-level acute inhalation exposure in workers has caused:
Nausea and vomiting
Neurological disorders
Bronchitis
Pulmonary oedema
Emphysema
Dermal or ocular contact with ethylene oxide solutions can cause eye and skin irritation in humans.
Animal tests indicate high acute toxicity from both oral and inhalation exposures.
Chronic Effects
Long-term, low-level exposure in workers has resulted in:
Irritation of eyes, skin, and mucous membranes
Brain and nerve function issues
Evidence suggests long-term high-level exposure (~700 ppm) may cause cataracts in humans.
EPA: No Reference Dose (RfD) or Reference Concentration (RfC) established.
CalEPA: Chronic reference exposure level of 0.005 mg/m³ based on haematological effects in humans.
Reproductive and Developmental Effects
Some evidence links inhalation exposure to increased miscarriage rates in female workers (acute and chronic exposure).
Animal studies have shown:
Fewer implantation sites
Reduced testicular weights and sperm concentration
Testicular degeneration
Cancer Risk
Occupational studies report elevated cases of:
Leukaemia
Stomach and pancreatic cancer
Hodgkin's disease
Data are considered limited/inconclusive due to small sample sizes and uncertain exposure levels.
Animal studies show lung, gland, and uterine tumours after inhalation exposure.
EPA: Probable human carcinogen (Group B1).
Provisional inhalation unit cancer risk estimate: 1.0 × 10⁻⁴ (µg/m³)⁻¹.
Safety
First Aid Measures
General: Consult a physician; show the SDS to attending medical personnel.
Inhalation: Move person to fresh air; if not breathing, give artificial respiration; seek medical advice.
Skin Contact: Wash with soap and plenty of water; take victim to hospital; seek medical advice.
Eye Contact: Rinse with water for at least 15 minutes; consult a physician.
Ingestion: Do not induce vomiting; never give anything by mouth to an unconscious person; rinse mouth; consult a physician.
Exposure Controls and Personal Protection
Exposure Controls
Implement appropriate engineering controls.
Avoid skin, eye, and clothing contact.
Wash hands before breaks and after handling the product.
Personal Protective Equipment
Eye/Face: Face shield and safety glasses compliant with NIOSH (US) or EN 166 (EU) standards.
Skin: Wear gloves; inspect before use; remove without touching the outer surface; dispose of contaminated gloves per regulations; and wash and dry hands after use.
Regulation
United States
OSHA: The Occupational Safety and Health Administration has established a PEL (permissible exposure limit) for ethylene oxide of 1 ppm (averaged over an 8-hour workshift)
OSHA: The Occupational Safety and Health Administration has established a STEL (short-term exposure limit) for ethylene oxide of 5 ppm (15 minute exposure)
NIOSH: The National Institute for Occupational Safety and Health has established a IDLH (immediately dangerous to life or health) concentration of 800 ppm
AIHA: American Industrial Hygiene Association has established an ERPG-2 (emergency response planning guideline) (maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to 1 hour without experiencing or developing irreversible or other serious health effects or symptoms which could impair an individual's ability to take protective action) of 50 ppm
Australia
Safe Work Australia: Safe Work Australia has established a time weighted average (TWA) concentration for ethylene oxide of 1ppm and 1.8mg/m3 for an 8 hour workday
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