Freedom of Information request on the safety of lateral flow tests containing ethleyne oxide (FOI 22/058)
Published 31 May 2022
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FOI 22/058
8th February 2022
Dear
Thank you for your information request, dated 13 January where you asked for “Could you please confirm taking a LFT daily as a close contact of Covid19 is still a safe limit given the swabs contain radiation and ethleyne oxide.
Please see your response to twice weekly lateral flows in May 2021.
I am pleased to provide you with the information requested, see below.
The MHRA is aware of concerns about the safety of using ethylene oxide (EO) to sterilise the swabs used in coronavirus testing kits (including lateral flow tests).
Ethylene oxide is a gas that is commonly used to sterilise many different types of medical devices, including swabs used in test kits.
The sterilisation process consists of a number of highly controlled and monitored stages, including removing ethylene oxide after treating the swabs. The amount of residual EO that is allowed has been set (by the international standard ISO 10993-7:2008) according to contact time of the medical device with the person. Contact time is divided into 3 categories: limited, prolonged, and permanent duration.
The swabs used in lateral flow test kits fall under the category of limited contact time. These limits are not further divided by body weight and therefore the limits set are also applicable for children.
These allowable limits were selected to ensure that any residual levels present on the medical device after sterilisation pose minimal risk.
The average time of contact for a single test (around 20 seconds) and the current testing regime (twice a week), means that each person is exposed to any residue on the swab for around 40 seconds per week. Calculating from the allowed residues, a person would need to be tested twice a week for over 40 years for the total contact time to be in a higher contact category. Therefore, the manufacturer’s original calculations that these swabs are in the ‘limited’ contact category are still valid for the current testing regime.
The manufacturer’s original calculations also remain valid for more intensive testing regimes required for some workplaces. Even with daily testing, the risk is still considered to be very low. This is because a person would need to be tested five times per week for over 17 years for the total contact time to be in a higher contact category.
Furthermore, due to the chemical nature of ethylene oxide, any residual amount left on the swab is likely to evaporate off once the packaging is opened.
In the highly unlikely event that a swab does contain a residual amount above the allowable limit, the risk to the user is still considered to be very low.
As part of the sterilisation process the manufacturer must confirm, and document, that the residual EO level on a medical device is below the specified allowable limit before the device is packaged ready for use. The whole process is overseen by an independent third-party organisations before a CE/CE UKNI/UKCA mark can be placed on the medical device. The identifying number of the third party can be found next to the CE/UKCA mark symbol on the packaging of the swab.
If you have a query about the information provided, please reply to this email.
If you disagree with how we have interpreted the Freedom of Information Act 2000 in answering your request, you can ask for an internal review. Please reply to this email, within two months of this reply, specifying that you would like an Internal Review to be carried out.
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Yours sincerely
MHRA Customer Experience Centre