The Chemical Used to Sterilise Your Medical Devices — What the Research Actually Says

Ethylene oxide (EtO) is a colourless gas used to sterilise medical devices that cannot withstand the heat of steam sterilisation — including plastic instruments, certain surgical tools, and some single-use devices. The US FDA estimates that approximately 50% of all sterile medical devices in the United States are sterilised using EtO. The picture in East Africa and globally is similar.

The reason EtO is so widely used is straightforward — it is extraordinarily effective at killing bacteria, viruses, and fungi at low temperatures without damaging heat-sensitive materials. No other sterilisation method currently available matches its combination of efficacy and material compatibility at scale.

The Classification That Raised Questions

In 1994 the International Agency for Research on Cancer (IARC) classified ethylene oxide as a Group 1 carcinogen — meaning there is sufficient evidence that it causes cancer in humans. Specifically, long-term occupational exposure to EtO has been associated with increased risk of lymphoma and breast cancer in workers at sterilisation facilities.

This classification is what has driven public concern — and legitimately so. The question, however, is not whether EtO is hazardous in high doses. It clearly is. The question is whether residual EtO on a sterilised medical device represents a meaningful exposure risk to a patient.

These are two very different questions. The research answers them differently.

What Residual Exposure Actually Looks Like

After EtO sterilisation, devices undergo a controlled aeration process specifically designed to off-gas residual EtO to levels below established safety thresholds. Regulatory bodies including the US FDA, the European Medicines Agency, and the ISO set strict limits on how much residual EtO is permissible on a device at the point of use.

ISO 10993-7, the international standard governing EtO residuals on medical devices, sets limits based on the type of device, how long it contacts the body, and what part of the body it contacts. For a device with brief external contact — which covers most single-use gynaecological instruments — the permissible residual limit is extremely low, measured in parts per million.

The regulatory framework is not theoretical. It is enforced, tested, and continuously reviewed. Devices that do not meet residual limits do not reach clinical use.

Where the Real Concern Lives

The legitimate public health concern around EtO is not patient exposure from sterilised devices — it is community exposure from sterilisation facility emissions, and occupational exposure for workers inside those facilities.

A 2020 investigation by the US EPA identified elevated cancer risks in communities near EtO sterilisation facilities in several US states. This is a real regulatory issue that has driven significant policy action — the EPA proposed new emissions standards for EtO facilities in 2023 specifically to address this.

Workers in sterilisation facilities who are exposed to EtO gas over years and decades face genuinely elevated cancer risk. This is documented, serious, and an ongoing area of occupational health research and regulation. These are the contexts where concern is both evidence-based and actionable.

What This Means for Your Healthcare Decisions

Understanding the difference between hazard and exposure is one of the most important concepts in health literacy. A substance can be genuinely hazardous — EtO clearly is — and simultaneously pose negligible risk in a specific, tightly controlled application.

Regulatory frameworks around medical device sterilisation exist precisely to manage this gap. The standards are not perfect, and ongoing scrutiny of both device residuals and facility emissions is appropriate and necessary. But the evidence does not support the conclusion that routine use of EtO-sterilised devices in clinical settings poses a meaningful cancer risk to patients.

The more productive questions to ask your healthcare provider are:

• 1

  Are the devices being used single-use and properly disposed of after each patient?

• 2

  Does the facility follow current sterilisation and aeration protocols?

• 3

  Does any device you are being asked to consent to have current regulatory clearance?

The Broader Point

Medical devices are not without risk. Regulatory systems are imperfect. Corporate incentives do not always align with patient welfare. These are legitimate concerns worth scrutinising carefully and continuously.

But scrutiny is most powerful when it is precise — when it identifies the specific mechanism of harm, the specific exposure pathway, and the specific evidence behind a claim. Broad distrust of medical devices based on mischaracterised risk does not protect people. It can, in some cases, discourage them from accessing care that would genuinely protect their health.

This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider for guidance specific to your health.