March 30, 2021
Our lips are not sealed
There are a few primary motives behind today’s menstrual product inventions- comfort to the user, health quotient and environmental sustainability. While all inventors may not experience menstruation, a certain degree of empathy and understanding is always essential, not just appreciable. I am writing in context of the recent invention and patent on menstrual adhesives which went viral and received flak for its lack of sensitivity in promotion of the concept.
Let us begin with the primary function of uterus, which is being the nourishing sac where a potential embryo develops. Unsuccessful fertilization of egg (in consonance with the complicated protective pathway of the menstrual cycle) causes the walls of uterus to shed, in a cyclic manner controlled by hormones and this is to be rejected from the body as menstrual blood. The lack of vesicle or bladder like function of vaginal canal or the uterus is a curious case for an evolutionary biologist to study. But to force the same to perform such a function, that is to hold the blood in the vaginal canal area is something to ponder about, so is the conjunction and comparison of a nutrient rich body fluid’s juxtaposition with body waste like urine and feces.
The adhesive which has been invented is supposed to form a seal on the labia minora, thereby seal the opening to exterior, and use labia minora and vaginal canal as the reservoir of menstrual blood. Although the idea can seem shockingly insensitive to menstruator’s, the science behind appears to have been inspired from an intriguing and hot topic of research in wound healing.
Several polymeric adhesives have been known to create hemostatic seal (Keeping blood within a vessel) which are widely put to test in cardiovascular surgeries and wound sealing. These polymers are known to form permanent seal on the wound in presence of blood under wet conditions where cross linking is not initiated by body fluids but by external physical or chemical factors (1).
In the above cases of wound healing the wound is to be sealed permanently, hence the cross linking is intended to be stable as long as possible. Blood or any body fluid does not affect the properties. Although the material is bio degradable and biocompatible, it is known to cause some inflammatory response.
While most body fluids in the context of wound healing (blood) have a neutral pH and requires a permanent seal, the invention in question is very different from the above scenario. The ‘mensez’ adhesive deals with the sensitive area of vagina and urethra and the labia minora surrounding them which exists at a relative acidic pH (4.5–6) to maintain the natural flora and prevent infection. The seal which the adhesive proposes to make is also a temporary one, as it disintegrates when the polymer comes in contact with urine. In order to be bio-compatible (refers to the suitability of use in the physiological environment without evoking an immune response) and biodegradable, the adhesive needs to be degraded by enzymes (in urine) not essentially hydrolytic, but requiring high enzymatic action, at a certain ionic strength of body fluid. Because the adhesive claims to be degradable when in contact with urine, the contents of urine and adhesive must essentially react and perform the disintegration of polymer.
Before creating the seal the labia minora is expected to be sphincterically contracted and brought closer to enable the joining. Now those who have tried doing kegel exercise will know how easy or difficult it is to contract those sphincter muscles and hold them in that position for a few seconds. The user is also expected to use fingers to bring the skin folds closer in case contraction is not enough. This is not withstanding the fact that vulva’s are unique, particularly the labia minora and maybe completely contained within the the outer labia, or maybe much longer and may protrude and extend considerably past the outer edges of the labia majora or maybe within the folds of the labia majora, making access and holding a job involving practice and tact. The labia minora also contains sebaceous and sweat glands making them moist, maintaining varying degrees of wetness or dryness. Further the skin can range from being wrinkled to smooth. This area is also the source of secretions from mucous glands in the vestibular region, apart from Bartholis and sometime Skene’s glands.
Once the adhesive is applied and seal formed, the skin will have to overcome the force acting against the seal. The shear force experienced every time when the seal is ruptured is described to be much lesser than 17 x10⁶ N/m2 or 17 MPa as it does not tear the skin. Now we do not know what the inventor implies by saying much less than 17MPa. It is noted from earlier research studies on dermal (skin) rigidity that stretchability of human skin decreases up to 50% after the age of 30 especially in women as compared to men. To get a perspective, the tough keratin rich outer layer of skin is known to have a stiffness factor close to 2.1 MPa which means, for a larger stretch or pull the skin experiences a distortion, which disappears over time depending on the skin’s flexibility, age and sex of the individual. We do not know what the inventor implies when he describes the release to be much less than 17MPa. Does this mean that before pulling apart, the tender skin is under a constant pure shear stress? Maybe. Maybe not. Imagine your eyelids to be sealed by an adhesive which could be opened only by your tears. We are only used to eyelids being shut while being asleep or at our will. If you wish to open the seal but are unable to do so due to the adhesive sticking your eyelids, one would tend to strain the skin trying to open it due to natural urge. The tendency to separate the eyelids will cause additional tension in your skin immediately surrounding the area sealed together. The mensez adhesive could well be intense than that. Labia minora is relatively much softer in nature than our outer skin, hence the repeated stretch and pull may adversely affect its shape, stiffness and hence its natural function, one of which is protection against infections. Even if infections were not to happen, it could strain the labia against natural movement such as regular sphincterical contraction or relaxation (just as your eyes would try to open after some sleep).
The inventor suggests direct application methods using fingers or by the use of brushes, swabs, rub on sticks (forget the potential infections/re-infections, unless its disposable, then the environmental sustainability), pump sprays, aerosol sprays (we are not guessing here what all the adhesive could seal on its way!)
By applying the adhesive a vesicle like space is thus created from vaginal canal and labia minora to allow the menstruator to discharge blood at convenience periodically. But one does not expect the blood to stay just inside the vaginal canal when it is sealed, as it has natural tendency to flow out and occupy the space just inside labia minora and remain in contact with vagina and urethra throughout. This is different from a scenario where blood comes out and gets absorbed onto cloth or reusable sanitary pad to congeal and coagulate. In case of menstrual cups or tampons this vesicular function is provided by the cups in an aseptic condition (using sterilized cups) before blood comes out of the vaginal canal, thereby avoiding contact with urethra altogether and making it safe for the user.
When one uses the adhesive we see that the blood is in contact with urethra and surrounding skin of labia minora in its liquid form. Now this is a new scenario which requires investigations to check susceptibility to UTI and all possible infections inside labia, among other potential chemical reactions between adhesive and the microbial flora in the space. The labia minora is not constantly sealed or opened throughout the day under its natural condition. This also is responsible for the nature of microbiota in the vaginal area and around urethra at different times during the menstrual cycle to maintain its natural pH and prevent urinary tract infections. As per recent research risk of recurrent UTI seems to be more from vaginal bacteria than external bacteria. The area inside inner labium is out of contact of air, if the seal is applied, which will affect the flora in the region. Each individual’s genital flora is unique and one cannot grow all the flora in labs (to have a back up microbiome) as not all organisms can be cultured! If one does manage to create a recombinant strain with the DNA of one’s own microbiome, it will still be different and may or may not express the entire genome. One definitely does not want new mutant species in an area already sensitive environment prone to UTI.
The possible constant wet feeling which will be experienced due to ‘blood holding vesicular function’ of the labia only makes us question the comfort factor of this product at a mildly superficial level.
Our lips are NOT sealed! Having laid the above facts together, it might seem that the cons of this new invention can act as a deterrent to being developed or used as a product. If some of the above questions were indeed addressed and feedback from informed and consenting menstruator’s were provided to gain a rounded perspective, one might then have the space to give this concept a serious shot than just critiquing. The patent per se might have little value currently, unless bought over by a big company invested in menstrual products that is willing to go through the journey of development, testing, prototyping and marketing. Or the patent might have significance in a hitherto unknown field of science and technology. As a menstruating human being, some of the ideas propagated by the innovator appalls me, as a scientist, I see the need to calculatingly critique the invention as is. For all one knows, this could be one phenomenon that the scientific fraternity has either overlooked or overlooked for good! Time will surely tell. In the meantime, let us not forget that the chemicals in the tampons and sanitary pads are toxic (veritably established by science), so switch to cups if you want to go green and feel free and healthier during periods, or reusable cloth pads whichever is comfortable to you.
Aishvarya is a passionate chemical scientist with a bigger penchant for environmental sustainability. A badminton player, a painter, a singer and a violinist in the making, she dons many hats with aplomb
(1) For instance hydrophobic light activated adhesive (HLAA) which is a water stable adhesive activated by light, is made from water repellent pre-polymer or raw material which leads to the formation of final functional polymer. Other chemically activated pre polymers are also known. It is necessary for the pre-polymers to exist in suitable form with appropriate viscosity, hydrophobicity and result in proper elasticity after cross linking to form stable seal on a moving tissue