Ethylene oxide used for sterilizing COVID-19 lateral flow tests poses no risk to public safety

By: Pallavi Sethi
January 10 2024

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Ethylene oxide used for sterilizing COVID-19 lateral flow tests poses no risk to public safety

A screenshot of a Facebook post erroneously claiming the ethylene oxide used in lateral flow tests is harmful. (Source: Facebook/Screenshot)


The Verdict False

The ethylene oxide levels in COVID-19 lateral flow test swabs adhere to safety guidelines and do not pose a risk to public health.

Claim ID 539784f3


The U.K. has seen a recent surge in COVID-19 cases around the festive season of Christmas and New Year. Data from the U.K. Health Security Agency indicates that over Christmas, more than 1 in 20 people in London tested positive for COVID-19. Amid this surge, misinformation related to the virus has resurfaced on social media.

Facebook post circulated a claim about lateral flow tests – a common method for detecting the virus. The post erroneously suggests that these tests are hazardous due to the presence of ethylene oxide in the swabs.

What is ethylene oxide?

The National Cancer Institute characterizes ethylene oxide (EtO) as a "flammable, colorless gas with a sweet odor." It is primarily used for sterilizing medical equipment and supplies, like lateral flow tests. It also plays a role in agriculture, where it is used for fumigating goods to protect them from pests and diseases. According to the U.S. Occupational Safety and Health Administration, long-term exposure to EtO can cause serious health issues, including leukemia.

Does EtO pose a risk in sterilizing lateral flow tests?

Although EtO is a carcinogen, its use in sterilizing lateral flow tests is considered safe. The International Organization for Standardization, a non-governmental international body, has set a maximum residue limit for medical devices sterilized with EtO. The specifications for permissible limits are designed to ensure that any residual amounts pose minimal risk to patients. These limits are based on the length of contact between the medical device and the person. The contact time is divided into three categories, regardless of whether the device is used once or repeatedly:

  • Limited Exposure – devices are used for up to 24 hours.
  • Prolonged Exposure - devices are used for more than 24 hours but less than 30 days.
  • Permanent Contact - devices are used for more than 30 days.

According to the Medicines and Healthcare Products Regulatory Agency (MHRA), the swabs in lateral flow tests are classified as having limited exposure (category 1) and are, therefore, safe. The MHRA further clarifies that the risk remains low even with daily testing. They explain that it would require more than 17 years of testing at a frequency of five times per week for there to be any significant increase in exposure and associated risk. Logically Facts has contacted the Department of Health and Social Care (DHSC) for comment and is currently awaiting their response. 

Sterilization compliance oversight

During the sterilization process, manufacturers must verify and record the residual EtO levels on a medical device, ensuring they fall within safe limits. Additionally, this process requires a compulsory conformity assessment conducted by an independent third-party organization, providing an extra layer of safety and protection. 


The use of ethylene oxide for sterilizing COVID-19 lateral flow tests is deemed safe for public use and poses no significant health risks. Therefore, we have marked this claim as false. 

The COVID-19 pandemic has given rise to a lot of potentially dangerous misinformation. For reliable advice on COVID-19, including symptoms, prevention, and available treatment, please refer to the World Health Organization or your national healthcare authority.

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We rely on information to make meaningful decisions that affect our lives, but the nature of the internet means that misinformation reaches more people faster than ever before