How it all started and what has happened to the industry since
There is no question that it was the Diva Cup that created the ground for all other brands to grow on. Diva Cup was the menstrual cup to gain FDA clearance first and it is still used to make new cup brands eligible for the FDA 510 k clearance process. 510 k takes effect when a medical device is substantially similar to a device already approved and in use.
Many new brands follow the basic Diva design: a 2-size cup made from silicone.
By the end of 2014 the FDA streamlined the clearance process allowing new brands to enter the market more rapidly. (more on that in a separate blog post)
Over the last 5 years the array of menstrual cups to choose from has exponentially increased. For manufacturers competing on the same concept this has made things more competitive.
Current Materials Available and Public Perception
Menstrual cups are made from three different substances worldwide. Silicone, TPE and Natural Rubber (made of natural gum, latex).
Before we go deeper into the subject it’s important to understand that each material can be formulated and used in a wide variety of ways.
The silicone used in industrial applications is not the same as the silicone used in implants.
The rubber used in your tires on your car is not the same as the latex used in surgical gloves.
TPE used in yoga mats is not the same as TPE used in medical devices.
Most cups offered are made from silicone. The likely reason is that the vast majority are manufactured in Asia. Production of the silicone later used in the production of items made from it is largely located in Asia due to the labor intensive nature of silicone creation.
Second in prevalence is TPE and lastly natural rubber. Silicone and TPE both fall under the man-made group. Building blocks made of both materials can be found in both groups of substances.
Both are artificial products that are manufactured to hold a certain shape.
Despite the man made nature of both silicone and TPE, public perception of silicone tends to be more favorable, especially in the US where TPE is still a relatively new material. This misconception of silicone as ‘more natural’, better plastic is likely based on two things:
- Silicone is labor intensive to produce. Therefore single use plastics don’t lend themselves to be made from LSR (liquid silicone rubber). If silicone was found more in single use items, we’d likely think of it as just as another plastic.
- With increasing competition and the emergence of other cup options, cup manufacturers had to find ways to differentiate themselves as the ‘better’ choice. Those manufacturers using identical concepts (2-size silicone cups) would of course be ill advised to disparage cups of the same type. One such manufacturer has been especially active in driving the narrative that TPE cups are lower value plastic and that silicone is somehow the ‘healthier’ plastic. (The truth is that both TPE as well as silicone can contain endocrine disruptors -more on that later)
Pros and Cons of different Cup Materials
There are only one or two menstrual cups made of natural rubber worldwide. There are reasons for this.
The growing demand for natural rubber (the precursor of latex) poses a major challenge to the world’s population. Southeast Asian farmers are cutting down native forests to grow rubber plantations, leading to the destruction of biodiversity. Furthermore, the resulting mono-cultures are very susceptible to disease. Since this material always has an increased risk of rubber/latex allergy in the user it may not be suitable for users with latex allergies.
It may also pose problems during manufacturing due the risk of allergy.
Latex cups can be a good option for users that do not have a latex allergy and are looking for a cup made from natural material.
One thing to keep in mind is that during the manufacturing process the cup takes on a new composition and is no longer biodegradable. The finished product contains natural rubber but has been processed much beyond the original raw material.
It is not recyclable other than to be used as filler for other products.
The labor-intensive silicon processing actually has and for the most part still does take place in China.
There are only four major players worldwide in regards to providing the raw material to silicone manufacturing:
- Dow Corning
- Momentive Performance Materials
- Shin-Etsu Chemical
- Wacker Chemie
In nature, only inorganic silicon compounds are found. Namely silicon dioxide, silicates and silica. All other silicon compounds -including silicone used for menstrual cups- are of synthetic, artificial origin. They can therefore be considered plastics.
‘Natural’ silicone is found exclusively in the language of advertising. Looking at the names of the companies manufacturing may also give you some insight into what type of chemical manufacturing is involved.
Siloxans are building blocks for silicone products. They have long been considered harmless, but newer evidence suggests negative effects on human health and the environment. There are cases of allergies due to the use of menstrual cups documented with the FDA.
After incidents involving menstrual cups made of silicone in Mexico, the Ministry of Health there classified menstrual cups as products subject to approval.
Siloxans have a wide range of applications due to their many different properties and are therefore widely used in products worldwide. They have been used in consumer products for three decades, especially in the cosmetics sector as a care and preservative.
Siloxans are silicon compounds, i.e. compounds of the elements silicon (Si), oxygen (O), carbon (C) and hydrogen (H). Siloxan compounds are produced purely synthetically, there are no natural deposits. One distinguishes linear (e.g. L3, L4, L5) and cyclic (e.g. D4, D5 and D6) siloxanas.
For humans, these substances were long considered toxicologically safe, but this can no longer be fully asserted: There are some siloxanes for which there is information on negative health effects through animal testing on rats.
In the European Union, only D4 is considered dangerous so far. The effects demonstrated in several studies indicate that it may affect reproductive capacity but may also have harmful effects in waters in the longer term.
By the way, D4 and D5 are not only used in personal care products. They are important raw materials for silicone plastics and can be found as residues in the finished products. Because of the particularly worrying characteristics, the Federal Environment Agency (UBA) considers it useful to include D4 and D5 in the REACH Candidate List. Inclusion in the list of candidates is a clear signal to replace a substance and triggers certain public information requirements for manufacturers, importers and retailers, which consumers can use to make informed decisions.
The Austrian Federal Office has taken a closer look at Siloxane. http://www.umweltbundesamt.at/umweltsituation/schadstoff/silox/
Like latex, once the compounds to create silicone are combined they can no longer be separated. At the end of the use-life the silicone can not be recycled into new products other than be shredded and used as filler, etc.
TPE (thermoplastic elastomer):
TPE production consumes less energy than silicone production. The term TPE encompasses a wide range of products with varying ingredients.
The major producer of TPE, Kraiburg, is located in Germany.
Kraiburg verifiably makes a medical grade TPE that does not contain plasticizer.
Notable is that FDA registered medical grade TPE has a cost about 700 percent (!) higher than regular use TPE made by the same manufacturer due to the requirements on the components and purity.
Both of the main suppliers for TPE menstrual cups use Kraiburg medical TPE.
Depending on the components used, TPE, being a man made product, may include similar substances as silicone.
TPE, being a thermoplastic elastomer, can have slightly different properties as compared to silicone cups. For example TPE conforms to its surroundings under the influcence of heat – even body heat. Since the vagina is not round TPE cups tend to form an oval. As long as the diameter is correct, the cup will seal fine but the change in shape can be concerning to users not familiar with TPE’s properties.
To date TPE has had fewer cases of allergies linked to it than silicone and latex.
TPE is generally recyclable. It can be melted back down by the use of heat (hence the name THERMOplast) and processed into other things.
For most areas TPE recycling options are however still limited at this time.
- Depending on allergies present in the user and components used for the raw materials all three cup materials can produce safe menstrual cups.
- Silicone cup manufacturers don’t manufacture their own silicone. TPE cup manufacturers don’t manufacture their own TPE.
- In regards to hormone disrupting components, both silicone and TPE materials have the potential to contain compounds with this effect.
- For TPE cups the critical issue is that the TPE used not contain any plasticizers. For silicone cups the component to watch out for are D4 and D5 siloxans.
- Menstrual cups with FDA clearances before 2015 had to prove biocompatibility and undergo extensive testing before receiving clearance for sale in the US.
For materials that are directly or indirectly in contact with living tissue – such as a menstrual cup- special conditions apply: The plastic must not damage the organism AND the biological surroundings can not affect the material properties of the plastic. If these conditions are met, there is biocompatibility. Part of biocompatibility and related testing is to confirm that no substances are contained in the material that can have an affect on the body (including endocrine system). Newer cups that were FDA registered in 2015 or later did not have to prove this before being cleared for sale. This does not rule out that they are in compliance with these standards. Theoretically they still have to pass these standard if they are FDA registered.
- To research the raw material of a specific cup brand it is generally easier to find manufacturer info on cups made from TPE. Keep in mind that even silicone cups manufactured locally likely obtained the silicone materials from one of the manufacturers listed above in the silicone section.
Different cup materials have different properties. You may have a preference for one over the other. A menstrual cup may be offered in certain models in a material that are not offered in other materials. Base your decision on those design elements that are important to you.
All three cup materials -silicone, TPE and latex- can be safe and free of hormone disruptors depending on raw materials used.
Don’t fall for marketing that tells you one material is automatically healthier or better. You are more discerning and informed than this! How safe any of these materials are depends on the components used in their respective raw materials.
Don’t purchase menstrual cups that do not meet the standards of your regulatory health agency (FDA for the US). The FDA has way more insight into what went into your menstrual cup than you will ever have, even with extensive research.
For example while the actual ‘recipe’ for a raw material may be propitiatory and not accessible by the public, materials that are registered with the FDA will likely have their master records on file with the regulatory agency. This includes colorants.
If you are concerned about the cup you are considering, feel free to inquire with the manufacturer about details. Transparency is a plus.