Fact Check-COVID-19 nasal swabs sterilised with ethylene oxide are safe to use

Nasal swabs included with COVID-19 tests have not been sterilised with the main ingredient in antifreeze, nor are they killing people, despite claims made in a video online.

The 80-second clip has been shared by hundreds of social media users and features an unidentified man refusing to take a swab – instead choosing to explain why he believes they pose a threat to health (here , here , here).

Pointing to the “sterile EO” note on the swab’s packaging, he says: “It’s sterilised here dry. No effect. But once you put it inside someone’s nose, it’s wet. Once you inhale it, it’s actually unbeatable. You can look it up. That’s going to kill us. It’s actually killing people.”

“Sterile EO” means the swab has been sterilised using ethylene oxide, a type of gas that the man also notes is a carcinogen. He adds: “So it’ll give you Hodgkins lymphoma and in females greatly increases chances of breast cancer.”

The man also says ethylene oxide is “the number one ingredient used in antifreeze”.

However, these claims are not true – and they appear to be a repeat of misinformation previously addressed by Reuters (here and here).

While it is accurate to say exposure to ethylene oxide has been associated with cancers (here), this does not mean that swabs sterilised with ethylene oxide will cause cancer.

“Ethylene oxide is a useful sterilising gas because it is very good at inactivating microbes. It is used in factories in an incredibly carefully controlled way, to make sure there is no hazard to people working at the factory,” said Dr Alexander Edwards, associate professor in biomedical technology at the University of Reading, in an email to Reuters.

“As it is a gas, there is no way it can be carried forward after the manufacture into any of these products. We know this from decades of safety and toxicity research. The use is strictly controlled and regulated.”

The US Food and Drug Administration (FDA), the United Kingdom’s Medicines and Healthcare products Regulatory Agency (MHRA) and other bodies have all documented the tight regulatory frameworks and international standards adhered to for EO use (here , here , here and here).

It is a common chemical used for sterilising medical equipment and leaves negligible amounts of product behind (here).

“It’s a bit like using bleach at home,” said Edwards. “People are generally happy to use dilute bleach or detergents and antiseptics to sterilise surfaces. No-one would think of eating or drinking the bleach- that would be incredibly dangerous. But we also know it’s safe if you use it carefully.”

In a statement to Reuters, a spokesperson for the United Kingdom’s Department of Health and Social Care said: “Ethylene oxide is only used in the sterilisation of swabs, and it is one of the most commonly used sterilisation tools in the healthcare industry, principally applied by manufacturers to keep medical devices safe.

“Lateral flow tests have been rigorously tested and are safe to use on a regular basis. Any suggestion otherwise is inaccurate and harmful misinformation.”

The claim that EO is one of the main ingredients in antifreeze is also untrue – and shows a misunderstanding of the science.

Rather than being used as an ingredient in antifreeze, EO is an intermediate to create other common chemicals such as ethylene glycol or polyethylene glycol, which are used in a wide range of applications such as detergents and antifreeze (here and here).

The gas itself “isn’t included in antifreeze,” Dr Edwards said. Antifreeze is a liquid, not a gas, and antifreeze is not useful as a sterilising agent.

He added: “It’s really easy to get mixed up with chemicals and materials with similar sounding names, which is why we have so much health and safety regulation to make sure medicines, cosmetics, foods and other products are safe to everyone.”


Missing context. EO is a gas used commonly used to sterilise medical equipment such as COVID-19 nasal swab tests. Although EO is carcinogenic, the use of the gas is tightly regulated and has been used for decades. The sterilisation process is controlled to ensure that any leftover EO on medical equipment is negligible. The EO used to sterilise lateral flow tests is different from ethylene glycol found in antifreeze.

This article was produced by the Reuters Fact Check team. Read more about our work to fact-check social media posts here.