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All you need to know about medical silicone

The materials used to make menstrual cups are of paramount importance. We have summarized our knowledge in this area so that you can make an informed choice.

What are menstrual cups made out of

To our knowledge, there are 3 materials for the manufacture of menstrual cups:

  • Most of them are made of medical silicone: we’ll develop this material further below because there’s a lot to be said about it.
  • Some menstrual cups are made of TPE medical (TPE = thermoplastic elastomer). It is a petroleum-based material tested for biocompatibility and complies with high medical standards (it is used for catheters, medical membranes, etc.). The major disadvantage of TPE menstrual cups is that they are not resistant to high temperatures: most TPEs are guaranteed stable below 125°C. However, when you boil your menstrual cup in water, it is already at 100°C. It must not remain in contact with the bottom of the pan, otherwise it will lose its physical and chemical properties.
  • Finally, we know of a natural rubber cup sold in the USA. However, rubber is still highly allergenic.
  • But let’s develop the most common material: medical silicone.

    What is silicone?

    Silicone is a polymer composed essentially of silicon and oxygen. Silicon is the second most abundant chemical element on Earth (just after oxygen): it represents 1/4 of its mass.

    Silicon is therefore not a plastic in the common sense of the term, as it does not come from the petrochemical industry.

    There is no oil in silicone, and it is finally closer to glass since, like it, its raw material is silicon, which is mainly found in sand.

    Silicone has a lot of applications: there are classic silicone, food silicone, medical silicone. Each has its own set of regulatory requirements, and of course medical silicone is used for menstrual cups.

    It also has a wide variety of consistencies: liquid, gel, gum, hard… We will come back to this later.

    The different types of medical silicones

    Medical silicone is used in wound treatment gels, orthopaedic products, seals for disposable syringes, medical tubing, anaesthetic masks and menstrual cups, among other things!

    But while all these applications are health related, they do not require the same level of purity. There is internal and external use, single use or durable use…
    So, all silicone menstrual cups are made of medical grade silicone. In order to obtain the consistency required to make a menstrual cup, a catalyst is added to the silicone, which will cure the material to the desired “shore” (the hardness or softness of a silicone is measured by a number of shore). And this catalyst has all its importance…

    Peroxide-catalyzed silicone

    It’s the first generation of medical silicones.
    Peroxide is a chemical active ingredient composed essentially of oxygen and carbon.
    It is a very powerful oxidant (it is the one that blurs the hair for example), naturally unstable (especially under the effect of heat), which is recognized as harmful to the body in certain quantities and exposure times.
    The peroxide reaction leaves an acidic residue on the surface which must absolutely be cured by a cooking process after moulding the menstrual cup.

    This silicone is cheap, but it can transfer volatile organic compounds, especially under the effect of heat. It has superior surface adhesiveness, which can lead to faster soiling. It is mainly used for single-use products.

    And unfortunately, it is also used for a lot of menstrual cups. Because there’s still some “medical silicone” left, which the “medical silicone” argument reassures on the box. And as the regulation is light regarding the manufacture of menstrual cups, nothing legally prevents the use of this type of silicone. But now you know.

    Platinum-catalyzed silicone.

    Platinum is a rare and precious (and expensive) natural chemical element, particularly stable and heat-resistant.

    It is mixed in minute proportions with silicone to harden it, and the reaction does not cause any release of by-products.
    Platinum-catalyzed silicones therefore have a higher level of purity and do not transfer residues.

    Medical platinum silicone is considerably more expensive than its cousin medical peroxide silicone, but it is totally atoxic, stable, odorless, non-sticky, hydrophobic and sterilizable: it has the best biocompatibility. It is also bacteriostatic, i.e. bacteria do not grow on its surface.
    It is obviously the one that we chose to make La Cup Luneale.

    What about antimicrobial silicone?

    You may have heard of antimicrobial silicone menstrual cups. And you may think it’s a good idea to keep germs out of the vagina.

    In fact, we looked into the matter to choose the ideal material to make La Cup Luneale: we wanted the best.

    But microbes are actually a common name for a set of 3 things: fungi, viruses and bacteria.

    Antimicrobial silicone is actually a silicone that has undergone a treatment with silver ions after being moulded. Silver ions are nanoparticles, which, depending on their size, can pass the skin barrier and whose effects on both health and the environment are still too vague. The French National Agency for Food, Environmental and Occupational Health and Safety (ANSES) has notably admitted an opinion on 5 March 2015 in which it” highlights the research efforts on the potential health and environmental effects of silver nanoparticles but notes that these remain however insufficient to allow an assessment of the health risks “. The Agency therefore recommends limiting the marketing of products to applications whose usefulness has been clearly demonstrated.

    In short, we don’t know much yet. What we do know, however, is that the vaginal flora is composed of bacteria. GOOD bacteria, which are necessary for intimate balance and which protect against most infections. So by weighing the potential benefits and risks, we have ruled out this type of silicone for our cups, as the usefulness of silver treatment has not been demonstrated for this application. Especially since platinum silicone is bacteriostatic.

    The special case of silicone breast prostheses.

    Breast prostheses consist of a medical silicone shell, itself filled with a liquid medical silicone gel. In the vast majority of cases, everything is OK and very controlled.

    The scandal that took place several years ago is due to an unscrupulous company that filled medical silicone envelopes with industrial silicone gel (used to lubricate machine tools etc…), which is obviously much cheaper.

    And when some of the envelopes were pierced, it was industrial gel that spilled into the bodies of the victims, causing serious after-effects.

    We hope we have enlightened you with this information, and that you will be wary of cheap cups. It is better to invest a little more, but be completely serene about the quality of the material.



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