Are Cervical Smear Tests Safe? What the Latest Claims About Sterilisation Really Mean

Claims circulating online have raised concerns about cervical screening, with some posts suggesting that the brushes used during smear tests are sterilised using chemicals that can cause cancer. These claims can understandably sound alarming, particularly when they involve a procedure designed to prevent cancer.

However, experts have pushed back against the suggestion that cervical screening is exposing patients to dangerous levels of cancer-causing chemicals. The key issue is the difference between a chemical being hazardous under certain conditions and a medical device that has been properly sterilised and prepared for patient use.

Cervical screening remains an important part of preventing cervical cancer in the UK. More than 3,000 women are diagnosed with cervical cancer each year, and screening can identify high-risk human papillomavirus, commonly known as HPV, before it causes serious changes to cells in the cervix.

Why has ethylene oxide been mentioned?

One of the chemicals at the centre of the online claims is ethylene oxide. It is a gas that is widely used in healthcare to sterilise medical equipment and devices that may be damaged by high temperatures or other sterilisation methods.

Ethylene oxide can present health risks when people are exposed to sufficiently high concentrations for prolonged periods. That fact is not disputed. The important question is whether a patient undergoing a cervical screening test is exposed to a harmful amount of the substance.

According to Professor Andrea Sella, a professor of inorganic chemistry at University College London, the sterilisation process involves exposing a medical item to ethylene oxide and subsequently removing the gas before the sterile item is packaged.

In other words, the presence of ethylene oxide during the manufacturing or sterilisation process does not mean that a patient is receiving the same exposure.

The Medicines and Healthcare products Regulatory Agency has also said there is no credible evidence that the swabs used for cervical screening are associated with cancer.

A hazardous chemical does not automatically make a medical device unsafe

This distinction is important when evaluating health claims online.

Many substances can be harmful at certain doses or under particular circumstances. The fact that a substance has been classified as hazardous does not necessarily mean that every product manufactured using that substance is dangerous to consumers.

Medical sterilisation processes are designed to eliminate microorganisms while ensuring that equipment is suitable for clinical use. In the case of ethylene oxide, the gas is removed as part of the sterilisation process before devices are supplied for use.

That means claims that simply state, "ethylene oxide can cause cancer", without explaining exposure levels and the sterilisation process, can create a misleading impression.

There is currently no credible evidence presented by the experts cited in the reporting to show that cervical screening brushes expose patients to cancer-causing levels of ethylene oxide.

Why cervical screening matters

The concerns surrounding sterilisation come at a time when participation in cervical screening has been falling.

Cervical screening is not designed to diagnose cancer in the same way that an investigation following symptoms might. Instead, it looks for high-risk types of HPV that can cause changes to cells in the cervix.

HPV is extremely common. Many people who acquire it will never develop serious health problems, and infections can often clear naturally. However, persistent infection with certain high-risk HPV types can cause abnormal cellular changes that may eventually develop into cervical cancer.

Finding these changes early gives healthcare professionals an opportunity to monitor or treat them before cancer develops.

Cancer Research UK has reported that cervical screening has a major impact on reducing the risk of cervical cancer. For women who were not vaccinated against HPV when younger, screening remains one of the most important ways of reducing their risk.

HPV vaccination provides another layer of protection

Cervical cancer prevention does not depend on screening alone.

The HPV vaccine provides substantial protection against the HPV types responsible for many cervical cancers. According to figures cited by Cancer Research UK, HPV vaccination is almost 90 per cent effective at preventing cervical cancer among women in their twenties who were offered vaccination at around 12 or 13 years of age.

Vaccination and screening therefore work together.

The vaccine reduces the likelihood of developing HPV-related disease, while screening can identify high-risk HPV infections and cellular changes that still occur.

Neither approach makes the other unnecessary.

What symptoms should women look out for?

Although cervical screening is an important preventive measure, people should not wait for their next screening appointment if they develop symptoms that could indicate a problem.

Possible symptoms of cervical cancer include unusual vaginal bleeding, including bleeding after sex, bleeding between periods or bleeding after menopause. Heavier periods than usual, changes in vaginal discharge and pain during sex can also be symptoms.

Pain in the lower back, pelvis or lower abdomen may occur as well.

These symptoms can have many causes and do not necessarily mean that someone has cervical cancer. Nevertheless, persistent or unusual symptoms should be discussed with a healthcare professional.

Screening is also not intended to replace medical assessment when symptoms are present.

Why misinformation can be particularly damaging

Health information spreads rapidly on social media, often without the context needed to understand scientific evidence.

A post may correctly identify that a particular chemical can be hazardous while leaving out crucial information about concentration, duration of exposure, manufacturing standards and the way a medical product is prepared before use.

That can transform a technically true statement into a misleading health message.

Cervical screening can already be an uncomfortable or anxiety-inducing experience for some people. Additional claims suggesting that the procedure itself causes cancer may discourage people from attending appointments.

That could have serious consequences because screening is intended to prevent cervical cancer rather than cause it.

What should patients do?

People who receive an invitation for cervical screening should consider attending unless a healthcare professional has advised otherwise. Anyone who has concerns about the equipment used during an appointment can also ask the clinician to explain the procedure and the devices being used.

If someone has seen social media claims about the safety of cervical screening, it is sensible to check the information against reliable sources rather than making healthcare decisions based on a post alone.

The NHS, Cancer Research UK and the World Health Organization are examples of organisations that provide evidence-based information about HPV, cervical screening and cervical cancer.

The central message from the experts cited in the recent reporting is straightforward: there is no credible evidence that cervical smear test brushes are causing cancer because of the sterilisation process.

The existence of a potentially hazardous chemical in a manufacturing process does not, by itself, demonstrate that a finished medical device is hazardous to patients. What matters is the actual level and duration of exposure, along with the safety controls applied during manufacturing.

For people eligible for cervical screening, the evidence continues to support attending appointments as an important way to reduce the risk of cervical cancer.

Source: The Independent on 20 August 2026, alongside information attributed to University College London, the Medicines and Healthcare products Regulatory Agency, Cancer Research UK and the NHS.

Disclaimer: This article is for general informational purposes only and is not medical advice. If you have concerns about cervical screening, unusual symptoms or your individual cancer risk, speak with a qualified healthcare professional. Do not delay medical care based solely on information found online.