E-numbers / Other additives / E946
also: Perfluorocyclobutane · PFC-318 · R-C318
A fluorocarbon gas used as a propellant in aerosol food products. Not currently permitted as a food additive in the UK or EU.
Scan a barcode to check a food for octafluorocyclobutane. NutraSafe Pro · £6.99/month · iPhone and Android
This is not a permitted food additive in the UK, so you will not normally find it on a UK label.
Why it’s worth knowing. This is not a permitted food additive in the UK, so you will not normally find it on a UK label.
Octafluorocyclobutane is a fully fluorinated cyclic gas (a perfluorocarbon) consisting of a four-carbon ring in which all eight hydrogen atoms are replaced by fluorine. It is chemically inert, colourless, and odourless at room temperature. In industrial use it appears in semiconductor manufacturing and as a refrigerant; it carries an E-number from earlier consideration as a food propellant.
As a propellant, the gas dissolves under pressure in a food product (such as a whipped cream or aerosol topping) and expands to foam or dispense the product when the nozzle is opened. Its chemical inertness means it does not react with the food it contacts. It has also been proposed as a packaging gas to displace oxygen and extend shelf life, though this use is not currently authorised in the UK or EU.
E946 is not currently an approved food additive in the UK or the EU, so it should not appear on labels of products sold in either market. In historical or non-EU contexts it has been associated with pressurised aerosol food dispensers such as spray creams. On a UK or EU label it would read as 'E946' or 'octafluorocyclobutane', but any food carrying that label in these markets would be non-compliant.
Perfluorocarbons such as octafluorocyclobutane are among the most chemically stable compounds known. They are not metabolised in the body and pass through the gastrointestinal tract without reaction. No carcinogenic or genotoxic potential has been identified for food-contact perfluorocarbons at levels relevant to propellant use. However, the EU has not granted it a positive opinion as a food additive, so formal safety data in food contexts are limited.
Perfluorocarbons are chemically inert, not metabolised by mammalian enzymes, and not known to accumulate in tissue following short-term oral exposure at levels typical of a propellant application.
Octafluorocyclobutane has a very high global warming potential (GWP) and a long atmospheric lifetime, placing it within the category of fluorinated greenhouse gases regulated under climate legislation. This environmental profile is one reason regulators have scrutinised its use as a propellant alternative to hydrocarbons, though the environmental concern is distinct from any human health signal.
Octafluorocyclobutane (RC318) is a fluorinated greenhouse gas with a high global warming potential, regulated under EU F-gas legislation independently of food law.
Because E946 is not an approved food additive in the UK or EU, no specific dietary group needs to screen for it in compliant UK food. Any food product in the UK or EU that lists E946 on the label would be non-compliant and should not be sold here.
E946 holds an E-number from an earlier period of EU additive consideration but was never granted positive authorisation for food use in the UK or EU. The absence of an approval is not a finding of harm, but it does mean the formal safety evaluation process for food use was not completed to a positive conclusion. In practice, UK and EU shoppers are not exposed to it through compliant food products.
It is not listed as a permitted food additive in the UK. It was never granted authorisation under UK or EU food law, so it cannot lawfully be used as a food additive in products sold here.
Outside food, it is used in semiconductor manufacturing as an etch gas and as a refrigerant. It has also been explored as a contrast agent in medical ultrasound in some countries.
No compliant UK or EU food product should contain E946. In markets where it has been permitted, it has appeared in pressurised aerosol food dispensers such as spray cream canisters.
Octafluorocyclobutane itself is a fully synthetic gas with no animal-derived components, so it would be considered vegan. However, this question is largely academic as the additive is not permitted in UK or EU food.
Last reviewed: 20 June 2026
It's the only app that does thisUKJaneK
You Need This AppGmac2005
Best AppGK getting skinny UK App Store reviews
NutraSafe reads the label and puts every additive into plain English, with the source, right in the app.
NutraSafe Pro · £6.99/month · iPhone and Android
