Agent Name

Ethylene oxide

CAS Number




Major Category



Dimethylene oxide; 1,2-Epoxy ethane; Oxirane; [NIOSH]




Colorless gas or liquid (below 51 degrees F) with an ether-like odor; [NIOSH] Vapor density = 1.49 (heavier than air); [HSDB]


Ethylene oxide sterilizers are used by medical and dental staff to sterilize heat-sensitive instruments. [p. 736, Harber] Occupational asthma from ethylene oxide has been reported in a nurse. [Malo]


Acute inhalation injuries result from exposures between 200 and 400 ppm. At higher concentrations, ethylene oxide (EtO) may cause neurological dysfunction. Chronic effects of exposure include reproductive toxicity and peripheral neuropathy. [LaDou, p. 501] The most common skin effects are irritation and second degree burns, but allergic contact dermatitis has been reported. [Sullivan, p. 1135] Healthcare workers performing EtO sterilization may develop cataracts. Highest exposures occurred during unloading (especially when the sterilization cycle was interrupted) and during cylinder changing. [J Occup Environ Med 1999 Jun;41(6):492-9] There is limited positive data that EtO causes spontaneous abortions in humans and birth defects and testicular damage in experimental animals. [ATSDR Case Studies #29] [Ethylene oxide allergy in dialysis patients. Purello D'Ambrosio F, et al. Nephrol Dial Transplant. 1997 Jul;12(7):1461-3.] [Airborne occupational contact dermatitis from ethylene oxide. Romaguera C, et al. Contact Dermatitis. 1998 Aug;39(2):85.] Liquid causes second degree burns after contact for a few minutes. [CHRIS] Corrosive to skin; [Quick CPC] "Germ cell mutagens that have shown to increase the mutant frequency in the progeny of exposed mammals." [MAK] "Although the IARC Working Group concluded that the epidemiological evidence for carcinogenicity of EO was limited, EO was classified as a category 1 carcinogen because of its rodent carcinogenicity, alkylating properties and ability to cause chromosomal aberrations. However, the substantial epidemiological evidence regarding carcinogenic effects of EO to date does not show any consistent carcinogenic effects in humans and clearly these alkylating properties have not led to any consistent cancer excess in exposed populations." [PMID 19430313]

Reference Link

OSHA Technical Links: Ethylene Oxide

Exposure Assessment
Skin Designation (ACGIH)





1 mg/m3, STEL(OSHA) = 5 ppm

Excerpts from Documentation for IDLHs

Reports of effects in humans include: nasal irritation after exposures to 12,500 ppm for 10 sec. Acute studies in animals have shown: death after exposure > 8000 ppm for 10 min.; no apparent injuries after exposure to 4000 ppm for 30 min., 2000 ppm for 60 min., or 500 ppm for 1 hr.

Odor Threshold Low

257 ppm

Odor Threshold High

690 ppm

Lethal Concentration

LC50 (rat) = 800 ppm/4H

Explanatory Notes

Detection odor threshold from AIHA (mean = 420 ppm);

Half Life

No reports found; [TDR, p. 694]

Reference Link

ATSDR Medical Management - Ethylene oxide

Flammability (NFPA)

4: Burns readily

Adverse Effects
Reproductive Toxin


Skin Sensitizer




Toxic Pneumonitis



Sensorimotor Neuropathy


Hepatotoxin, Secondary


Skin Burns

IARC Carcinogen

Known Carcinogen

NTP Carcinogen

Human Carcinogen

ACGIH Carcinogen

Suspected Human

Links to Other NLM Databases
Health Studies

Human Health Effects from Hazardous Substances Data Bank:

Toxicity Information

Chemical Information

Search ChemIDplus

Biomedical References

Search PubMed

Related Information in HazMap

Occupational diseases associated with exposure to this agent:


Industrial Processes with risk of exposure: