Half of all medical devices in the U.S. that require sterilization use EtO to do it—these findings come as EPA prepares new regulations for emissions from medical device sterilizers this year

CHICAGO (July 28, 2022) — A new systematic review of the most recent studies on inhaled ethylene oxide exposure and cancer finds a lack of evidence of a clear and consistent relationship with stomach, breast, and lymphohematopoietic (LHM) cancers. The findings have been published in Chemico-Biological Interactions, a well-regarded journal of molecular, cellular, and biochemical toxicology. 

This systematic review focused on three types of cancer noted by the World Health Organization’s International Agency for Research on Cancer as being linked with ethylene oxide at high exposure levels. In total, the quality of 24 primary epidemiological and experimental animal studies and more than 50 mechanistic studies were assessed, according to established scientific guidelines.

The findings of this systematic review indicate a lack of evidence of ethylene oxide’s association with all three cancer types at current levels of human relevant exposure. These findings support similar conclusions of an earlier review (Vincent et al, 2019), and should help address concerns, particularly of people who live near or work at sterilization facilities, and the medical and health care professionals and hospital workers who regularly use products sterilized by the gas.

This new review was conducted by a team of scientists led by Heather Lynch, MPH, that included Jordan Kozal, Ph.D., Anthony Russell, MPH, William Thompson M.S., Haley Divis, Rachel Freid, MPH, and Kenneth Mundt, Ph.D., all of Cardno ChemRisk, along with Prof. Edward Calabrese of the University of Massachusetts, Amherst. 

“Our systematic review blended the strongest elements from several leading frameworks, including those of the U.S. EPA Toxic Substances Control Act, the National Toxicology Program (NTP) Office of Health Assessment and Translation, and the National Academy of Medicine (formerly the Institute of Medicine),” said Heather Lynch, MPH, of Cardno ChemRisk. It also used PRISMA guidelines, considered the gold standard for systematic reviews and meta-analyses.

Lynch continued, “When we integrated the scientific lines of evidence, we found the occupational levels of ethylene oxide in the last several decades—which are orders of magnitude higher than those measured in communities surrounding operations using EtO—do not induce the changes in cells and laboratory animals exposed at much higher concentrations. This largely explains why we don’t see excess cancers occurring in these workers.”

Ethylene oxide is a gas that has been used in many industries for over a century. It removes bacteria from materials and foods without causing the damage that occurs with other methods, such as high temperatures or acid. Importantly, more than 20 billion medical devices sold in the U.S. each year—about half of all medical supplies that require sterilization in the United States—are sterilized with ethylene oxide, making it essential to protect the patients whose lives and health depend upon these devices.

“State and regulatory systems should consider these findings in their deliberations on the safety of ethylene oxide, especially its use in essential medical applications,” said Jacob Traverse, president and CEO of the Center for Truth in Science. 

This systematic review was funded by the Center for Truth in Science, an independent non-profit dedicated to exploring the intersection of science, justice, and the economy.

To view the review, visit: H. Lynch, J.S. Kozal, A.J. Russell, W.J. Thompson, H.R. Divis, R.D. Freid, E.J. Calabrese, K.A. Mundt, Systematic review of the scientific evidence on ethylene oxide as a human carcinogen, Chemico-Biological Interactions (2022), doi: https://doi.org/10.1016/j.cbi.2022.110031.

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