Ethylene oxide (EtO) is a flammable, colorless gas recognized by its sweet odor. It serves as a foundational chemical in various industrial processes and is also utilized for its sterilizing properties.
Primary Uses and Sources of Ethylene Oxide
Ethylene oxide has two primary applications: as a chemical building block and as a sterilizing agent. In manufacturing, it is a precursor for numerous products, including ethylene glycol, used in antifreeze and polyester production. It also contributes to the creation of glycol ethers, found in solvents and brake fluids, and ethanolamines, used in detergents.
Another main use of ethylene oxide is for sterilization, particularly for medical equipment that cannot withstand high heat or moisture, such as catheters and surgical tools. Approximately 50% of all sterile medical devices in the United States are treated with ethylene oxide annually. It is also employed to reduce microbial levels in spices, cosmetics, and certain agricultural products.
Exposure to ethylene oxide predominantly occurs through industrial sources. Facilities that manufacture or utilize EtO, such as chemical plants and commercial sterilization operations, are the primary emitters of the gas into the air. The general public’s main route of exposure is by breathing air contaminated with these emissions, especially for those living near such industrial sites.
Health Risks Associated with Exposure
Exposure to ethylene oxide can lead to a range of health effects, categorized by the duration of contact. Short-term, or acute, exposure to high concentrations can cause immediate symptoms, including:
- Irritation of the eyes, nose, throat, and mucous membranes
- Respiratory issues like coughing, shortness of breath, and wheezing
- Headaches
- Dizziness
- Nausea
- Vomiting
- Diarrhea
- Fatigue
- Muscle weakness
- Seizures
Chronic exposure to ethylene oxide presents severe and lasting health concerns. Regulatory bodies such as the U.S. Environmental Protection Agency (EPA) and the International Agency for Research on Cancer (IARC) classify ethylene oxide as a human carcinogen, linking long-term inhalation exposure to an increased cancer risk.
Chronic Health Effects
Specific cancers associated with chronic ethylene oxide exposure include lymphohematopoietic cancers, such as non-Hodgkin lymphoma, lymphocytic leukemia, and multiple myeloma. There is also an elevated risk of breast cancer, particularly among women. Beyond cancer, long-term exposure can cause reproductive harm, including miscarriage, infertility, and damage to male reproductive organs. Neurological effects, such as memory loss, impaired hand-eye coordination, neuropathy, and numbness, have also been observed.
Populations at Highest Risk
Certain groups face higher ethylene oxide exposure due to their work or proximity to industrial facilities. Occupational settings represent one such group, including workers in chemical manufacturing plants, medical device sterilization facilities, and operations that fumigate spices or other products. Healthcare technicians who operate sterilizers in hospitals also have increased potential for exposure.
These workers can experience higher-than-average exposure levels, often through direct handling of the chemical or working near sterilization chambers. Brief, concentrated bursts of the gas can occur, for instance, when a sterilizing chamber door is opened.
Another significant group at risk are community members living near facilities that release ethylene oxide into the air. These areas are sometimes referred to as “fenceline communities” due to their close proximity to industrial sites. The risk generally increases the closer an individual lives or attends school to an emitting facility. Some regions even contain “sterilizer hotspots,” where multiple commercial sterilization facilities are located near each other, potentially compounding exposure.
Governmental Safety Regulations
Government agencies regulate ethylene oxide to protect workers and the public. The Environmental Protection Agency (EPA) focuses on community air quality, developing emission standards for industrial facilities that release hazardous air pollutants, including ethylene oxide. The EPA recently finalized more stringent air emission standards for commercial sterilizers, which are projected to reduce ethylene oxide emissions by over 90%. The agency has also expanded Toxics Release Inventory (TRI) reporting requirements for certain sterilization facilities, increasing public access to information on chemical releases.
The Occupational Safety and Health Administration (OSHA) ensures worker safety by setting limits on workplace exposure to ethylene oxide. OSHA has established a Permissible Exposure Limit (PEL) of 1 part per million (ppm), averaged over an 8-hour workday. There is also a short-term excursion limit of 5 ppm, averaged over any 15-minute period. An “action level” of 0.5 ppm over an 8-hour time-weighted average triggers additional compliance activities for employers, such as periodic air monitoring and medical examinations for employees.
Steps to Take for Suspected Exposure
If you believe you have been exposed to ethylene oxide, especially if you are experiencing symptoms, consult a healthcare provider. Medical treatment for ethylene oxide toxicity involves supportive care, focusing on maintaining respiratory and cardiovascular functions. Removing yourself from the suspected exposure source is also recommended.
For community members concerned about potential exposure from nearby industrial facilities, resources are available. The EPA’s Toxics Release Inventory (TRI) can identify facilities that report ethylene oxide emissions in your area. Contacting your local or state health department can also provide guidance relevant to your community’s air quality and any ongoing monitoring efforts.