Reference summary — not medical advice or a personal risk estimate.
Ethylene oxide
Quick answer
Classified as Group 1 — carcinogenic to humans, based on limited evidence in humans, alongside stronger evidence in animals. Breathed. Occupational — workers in medical-device sterilisation plants. Communities near such plants can have elevated air exposure.
Summary
A gas used to sterilize medical devices. Associated with leukemia and lymphoma.
Detail
Ethylene oxide is Group 1. The human evidence is limited (lymphatic and haematopoietic cancers, and breast cancer). The classification rests on that together with sufficient evidence in animals and strong evidence that it damages DNA. Communities near medical-device sterilisation plants have been identified by environmental regulators in multiple countries as zones of elevated exposure.
What's not established
This classification is based on limited evidence in humans, sufficient evidence in animals and strong mechanistic evidence. It does not establish a safe exposure threshold, your personal risk, or how this factor's risk compares in size to other Group 1 agents — hazard classifications are not ranked by magnitude.
Regional relevance
global
Documented in these products
Presence in a product category doesn't imply the product causes cancer. Click each to see the source and context.
Evidence sources
Every claim on this page traces back to one of these. Click through to read the primary document yourself.
Primary sources
NCI
NCI — Cancer-Causing Substances in the Environment
IARC
IARC Monographs — Classifications by Cancer Site, Vols 1–140
Supporting sources
ACS
ACS — Known and Probable Human Carcinogens
EPA
US EPA — Integrated Risk Information System (IRIS) carcinogen assessments
NTP
NTP — Report on Carcinogens (US National Toxicology Program)
Last reviewed: October 2026
Official reference list
A government list some readers use alongside the primary evidence. Meyron is not affiliated with it. A chemical being listed does not by itself describe a risk from any particular product.
- California Prop 65 list
State of California's list of chemicals known to cause cancer or reproductive harm.