Proposed regulations from the Environmental Protection Agency (EPA) are designed to sharply reduce worker exposures to ethylene oxide (EtO) sterilant and prevent occupational cancer.
EtO is used on approximately 50% of all sterilized medical devices annually, including an estimated 95% of all surgical kits. EtO can sterilize heat- or moisture-sensitive medical equipment without causing any damage.
“Presently, there are no viable alternatives to EtO for the sterilization of certain medical devices and equipment,” the EPA stated. “The absence of EtO for use on medical devices and equipment would cause widespread disruption to the availability of sterile medical devices.”1
Moreover, the Association for the Advancement of Medical Instrumentation (AAMI) cited the problem of healthcare-associated infections to patients, which worsened considerably during the pandemic. “One way to prevent these healthcare-associated infections in healthcare facilities is effectively reprocessing and sterilizing medical devices by EtO,” AAMI noted. “Ethylene oxide gas must be used with care because of its toxicity and (when used in its pure form) its flammability and explosiveness. For these reasons, EtO should be used to sterilize only those items that cannot undergo the steam sterilization process.”2
But something had to change. In a process that has evolved over time, the simple fact is much of the medical equipment used in the United States is sterilized with an antimicrobial pesticide and known carcinogen. Unless meticulously controlled and mitigated through various stages of use and exhaustion of the gas, EtO can pose a risk to hospital workers, as well as large free-standing sterilization sites — and the neighborhoods near them.
“EPA is moving urgently to advance new protections based on the agency’s latest assessment of cancer risks from EtO exposure in occupational settings, which are more significant than previously understood,” the EPA stated. “EPA’s new analysis estimates the additional lifetime cancer risk associated with continuous workplace exposure to EtO for eight hours a day, for 240 days per year, over a period of 35 years in an occupational setting is between 1 in 36 and 1 in 10 for workers who apply EtO in sterilization facilities. [The cancer risk] is between 1 in 25 and 1 in 12 for workers who apply EtO in healthcare facilities.”
EtO is carcinogenic to humans by the inhalation route of exposure.
Health Worker Died of Leukemia
The CDC is unequivocal about the dangers of EtO, noting the sterilant can be so easily absorbed by other materials, and that if not properly aerated, it can cause damage due to chemical residue on an implant within the patient.
“Injuries (e.g., tissue burns) to patients have been associated with EtO residues in implants used in surgical procedures,” the CDC stated. “Occupational exposure in healthcare facilities has been linked to an increased risk of spontaneous abortions and various cancers.”3
The EPA said a review of reported incidents in the United States from 2008 to 2022 included a hospital employee who was diagnosed with leukemia after six years of employment.
“Although EtO is a known carcinogen, it is not possible to determine if the cancer in this incident was caused by EtO exposure and/or some other factor(s) based on the available information,” the EPA said. “The agency intends to monitor human incidents for EtO and will conduct additional analyses if necessary.”
OSHA has established permissible exposure limits (PELs) of 50 parts per million airborne EtO in the workplace, expressed as a time weighted average for an eight-hour work shift in a 40-hour work week.
However, the EPA noted OSHA’s standards are outdated and hard to change. The agency is going further in its requirements as allowed under the Federal Insecticide, Fungicide, and Rodenticide Act.
“With few exceptions, OSHA’s PELs have not been updated since they were first established starting in 1971,” the EPA noted. “OSHA has recognized that many of its PELs are outdated and inadequate for ensuring protection of worker health. [This] allows EPA to consider more sensitive endpoints and working populations than OSHA’s risk evaluations typically contemplate. EPA’s risk assessment has found risks of concern to workers associated [with] registered uses of EtO, even when the applicable OSHA requirements are being met.”
For its part, OSHA released a statement clarifying they are on board. “We will continue our partnership with EPA and other federal agencies to reduce risks for people who work every day to maintain our nation’s vital medical device supply chain,” said Douglas L. Parker, assistant secretary of labor for OSHA.4
Hospital Requirements
While aimed primarily at free-standing sterilization facilities — particularly after it was discovered that EtO could leak from these sites into surrounding communities — the EPA also is seeking comment on several provisions to protect hospital workers.
Healthcare facilities use much smaller volumes of EtO than the free-standing sterilization facilities, but “given the low concentration at which EtO may present inhalation cancer risks of concern, EPA now believes additional risk mitigation measures are needed,” the EPA stated.
As of 2010, hospital sterilization is required to be performed in a so-called “all-in-one” chamber where the various stages of EtO application are followed by aeration in the same unit to remove residue and absorption.
“Most modern EtO sterilizers combine sterilization and aeration in the same chamber as a continuous process” the EPA noted. “These facilities sterilize material in oven-sized chambers using 4.5 to 170 grams of EtO per load. The exhaust from the chambers is typically routed to an air pollution control device, and the room air is typically ventilated though an exhaust stack.”
These measures, which some hospitals may already be taking, would be required two years after the EPA rule is finalized. The EPA is requesting comments on provisions for hospitals that include the use of respirators not typically used in hospitals. The EPA wants to know the feasibility of using “supplied airline respirators or self-contained breathing apparatus (SCBA) respirators in healthcare facilities for employees who are unloading EtO sterilization equipment from the sterilization chamber.”
Although designs vary, the air supply model provides air from another source beyond the work area and could be plugged into a wall or stationary equipment. The SCBA is a breathing system worn by the employee, with a positive pressure inhalation device on the face supplied by a tank of compressed air worn on the back.
Also, the EPA proposed requiring all-in-one sterilization devices to be in a containment area physically separate from all other work areas of the healthcare facility. The room would be under negative pressure to prevent gas dispersion.
The EPA also proposed requiring additional abatement devices along with all-in-one sterilization devices in healthcare settings. Accessory abatement devices can reduce EtO emissions by more than 99%. After that, the EtO would be vented through exterior ventilation stacks that serve the sterilization area only. The use of these abatement devices and the other interventions should reduce the risk of exposure to EtO in areas around a hospital to close to zero.
“This would [also] ensure that there is minimal EtO exposure for workers and bystanders within healthcare facilities,” the EPA said. “The system should route the EtO directly to the outside of the building by maintaining a net suction on all of the exhaust ductwork.”
The EPA was conscious of the burden these requirements may put on hospitals, even conceding the new masks and air hoses may be awkward to use at first. “The agency acknowledges that there would be impacts to healthcare facilities from implementation of engineering controls,” the EPA stated. “Through discussions with industry leaders, the agency determined that some engineering control measures described in this section may already be common practice while others would impose costs from retrofitting existing facilities to meet the new standards proposed. The agency seeks public comment on the cost and time necessary for registrants to implement label amendments requiring the implementation of the proposed engineering controls.”
These engineering controls would be implemented within two years after the regulation is finalized.
Cancer Risk on 109 Tracts of Land
The requirements for free-standing EtO sterilization sites were appropriately more prescriptive, with the EPA saying “people who go to school near [commercial] places where EtO is used are also potentially at an elevated risk of cancer due to EtO levels in the air. Actual risks will vary based upon a facility’s control measures for workers and community members and the distance and amount of time people live, work, or go to school near a facility.”
The issue blew up in 2018 when a federal study5 by the EPA’s National Air Toxics Assessment warned of potentially high risks of cancer in 109 census tracts nationally that were near plants that use EtO sterilization. Lawsuits are still being filed, including one by the nonprofit Earth Just, against the EPA for its “failure to take legally required action to protect the public from harmful carcinogenic air emissions from ethylene oxide sterilization facilities.”
The EPA is acting now, saying, “There are 85 commercial sterilization facilities in this source category, many of which are located near residences, schools, and other public facilities. Many of these facilities are also located in communities with environmental justice concerns. [It has been] determined that approximately 23 of these facilities pose elevated lifetime cancer risks to the surrounding communities.”
Saying that most free-standing sites are using more EtO than is needed, the EPA recommended most devices be sterilized at concentrations no higher than 500 mg/L. However, that would require “extensive” cycle experimentation and redesigning of devices, as well as validation and review. Public commenting is open on the feasibility of a two-year compliance timeline for use rate reduction through reduced concentrations of new cycles. To limit the EtO concentration to 500 mg/L for existing cycles, EPA proposed a five-year compliance time frame.
The EPA also would require engineering controls that reduce worker exposures to EtO, such as automation or emissions capture technology. Personal protective equipment (PPE) would be mandated in sterilization facilities when EtO is detected using state-of-the-art monitoring technology. This PPE would include supplied airline respirators or SCBA respirators.
“The agency also proposes to require the addition to EtO product labels of a respirator statement to mitigate potential inhalation exposure risks to workers involved in the EtO commercial sterilization process and adding any associated fit testing, training, and medical evaluation,” the EPA said.
The EPA predicted the interventions will reduce EtO emissions from these facilities by 80%, bringing the rate below the EPA’s Clean Air Act benchmark for elevated cancer risk.
Editor’s note: To submit a comment on the EPA action go to https://www.regulations.gov and enter Docket ID No. EPA-HQ-OAR-2019-0178-0154. Comments must be received on or before June 12.
REFERENCES
- Environmental Protection Agency. Ethylene oxide: Proposed Interim Registration Review Decision. Case Number 2275. March 2023.
- Association for the Advancement of Medical Instrumentation. ANSI/AAMI ST41:2008/ (R)2018 Ethylene oxide sterilization in health care facilities: Safety and effectiveness. 2008.
- Centers for Disease Control and Prevention. Ethylene oxide “gas” sterilization: Guideline for disinfection and sterilization in healthcare facilities. Page last reviewed Sept. 18, 2016.
- Environmental Protection Agency. EPA proposes new standards to protect public health, reduce exposure to ethylene oxide pollution. April 11, 2023.
- Environmental Protection Agency. National Air Toxics Assessment. Last updated Feb. 8, 2023.
Ethylene oxide (EtO) is used on approximately 50% of all sterilized medical devices annually, including an estimated 95% of all surgical kits. EtO can sterilize heat- or moisture-sensitive medical equipment without causing any damage. Proposed regulations from the Environmental Protection Agency are designed to sharply reduce worker exposures to EtO sterilant and prevent occupational cancer.
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