Absorbency of Biodegradable Materials for Menstrual Hygiene Management Products in Low-and Middle-income Countries

Introduction Methods realistic experiment. The results showed that bamboo wadding (a fabric used inside quilts and children’s coats) exhibits the highest absorptivity, greater than cotton terry cloth, hemp cloth, linen and a commercial sanitary pad. This is an encouraging nding as bamboo plants are widely available in tropical countries such as India and regions of Africa. Though the absorptivity index of bamboo wadding is promising, challenges lie in overcoming complex extraction processes to create wadding from bamboo plants which is discussed.


Introduction
Girls in low-and middle-income countries struggle to maintain good menstrual hygiene in part due to a lack of affordable sanitary products. The unaffordability of reliable sanitary products can lead to school absenteeism and is a barrier to education attainment and gender equality for girls in low income contexts. Further the lack of adequate disposal facilities can lead to social embarrassment and environmental pollution.

Methods
Low-cost biodegradable absorbents (cotton terry cloth, linen, hemp cloth and bamboo wadding) were investigated in gelatine solution in terms of their absorptivity for use in menstrual hygiene.

Conclusions
Though the absorptivity index of bamboo wadding is promising, especially in the light of the vast availability of bamboo in tropical low-and middle income countries, challenges lie in overcoming complex extraction processes from bamboo plants which is discussed.

Plain English Summary
The effective management of menstruation has been identi ed as a challenge for girls in low-and middle-income countries in part due to a lack of affordable sanitary products. Traditional ways of managing menstrual bleeding is the use of old clothes, paper, cotton, wool pieces, and even leaves which have unreliable levels of absorbency and increase vulnerability to urinary and reproductive tract infections which can also lead to longer term reproductive issues. The unaffordability of sanitary products also restricts active participation of girls in school, with many girls in India and Africa absent from school when menstruating due to unreliable traditional products, insu cient private changing areas, poor water/sanitation, and inadequate disposal facilities. This results in disposal of menstrual hygiene products in deserted areas or in latrines to avoid embarrassment, causing environmental pollution. This study investigates low-cost biodegradable materials (cotton terry cloth, linen, hemp cloth and bamboo wadding) in terms of their absorptivity for use in menstrual hygiene. A gelatine solution was used to imitate the viscosity of menstrual uid to provide a more realistic experiment. The results showed that bamboo wadding (a fabric used inside quilts and children's coats) exhibits the highest absorptivity, greater than cotton terry cloth, hemp cloth, linen and a commercial sanitary pad. This is an encouraging nding as bamboo plants are widely available in tropical countries such as India and regions of Africa. Though the absorptivity index of bamboo wadding is promising, challenges lie in overcoming complex extraction processes to create wadding from bamboo plants which is discussed.

Background
Women in low-and middle-income countries struggle to maintain good menstrual hygiene. This is in part due to a lack of affordable sanitary products [ 1 ]. Poor menstrual hygiene can cause increased vulnerability to urinary and reproductive tract infections, which can lead to infertility and other reproductive organ issues [ 2 , 3 ]. Moreover, unaffordability of sanitary products restricts active participation of girls in school, contributing to gender inequality.
For example, as high as 40% of girls in India are absent from school when menstruating [ 4 ] and in Africa it increases to 66% [ 5 ]. If sanitary products could be made affordable in terms of cost and product quality, then it will be possible to signi cantly increase school attendance, allowing girls to complete their basic education [ 6 ]. As widely reported in literature, females staying longer in school is linked to reduced maternal death; improved population health; increased contraceptive uptake; improved child health; increased vaccination rates and decreased HIV infection rates [ 7 , 8 ].
The traditional ways of managing menstrual bleeding in such countries is the use of old clothes, paper, cotton, wool pieces, and even leaves which have unreliable levels of absorbency. These unreliable absorbents of traditional menstrual hygiene products can keep girls away from attending school. Therefore, provision of superior absorbents and cost-effective menstrual hygiene products can reduce fears of soiling outer garments allowing better school attendance [ 9 ]. Further, schools have insu cient private changing areas, poor water/sanitation, and inadequate disposal facilities. This results in disposal of menstrual hygiene products in deserted areas or in latrines to avoid embarrassment, causing environmental pollution [ 10 ]. One of the ways to address this matter is the use of fabric pads and/or disposable pads manufactured from biodegradable materials such as bamboo bres, hyacinth and banana bres. Having said that, commercial biodegradable products are not readily available and cost-effective which restricts broad penetration of these products into low-and middle-income communities [ 11 ]. Thus, an alternative approach is required that will address how commonly available fabrics of biodegradable natural bres can be used as sanitary pads. This could help billions of women in low-and middle-income countries to improve menstrual hygiene management. Additionally, this paper is in line with the broader "MHM in Ten" 2014-2024 global agenda of providing girls with support in the school environment to manage menstruation with dignity, safety and comfort. Speci cally, it responds to the recommendations to advance the agenda of 'Priority 1: Build a strong cross-sectoral evidence base for MHM in schools for prioritization of policies, resource allocation, and programming at scale'. It could address the need for 'natural experiments' to understand the funding and policy implications of MHM programs in schools that provide menstrual products to girls in middle and low income countries [ 12 ]. Further, this study which provides new preliminary evidence in the area of health, e cacy, environmental safety of menstrual products is in line with the global consensus regarding adolescent menstrual health in low-and middle income countries and suggestions for future action and research [ 13 ].
The aim of this investigation is to analyse the absorption capacity of readily available, natural biodegradable materials for the purpose of feminine sanitary hygiene products in low-and middle-income countries. Together with that, strategies of using these natural biodegradable materials in a cost-effective way by involving local NGOs were also discussed.

Biodegradable materials for sanitary pads
The most common material used for commercial sanitary pads is superabsorbent polymer (SAP). The challenges regarding SAP are that it is expensive, and the production is more technical, requiring a high level of capital and complex machinery.
In contrast to SAP, natural plant bres are cellulose-based and attract water which make them highly absorbent. The structure of plant bres changes dimensions with changing moisture content because the cell wall contains hydroxyl and other oxygen containing groups that attract moisture through hydrogen bonding. Moisture swells the cell wall, and the bre expands until the cell wall is saturated with water. Beyond this saturation point, moisture exists as free water in the void structure and does not contribute to further expansion. Superabsorbent polymer can absorb up to own weight [ 15 ].
Linen bres, which are obtained from the ax plant, have less absorbency than cotton bres [ 16 ]. Cotton terry cloth, where cotton bres are woven in loops, is more absorbent than standard cotton. The surface area of the loops is designed to absorb liquids and the ability of absorption is driven by fabric weight, thickness, and pile yarn twist [ 17 ]. Hemp or industrial hemp is a natural bre from a variety of the Cannabis sativa plant. Hemp has mildew resistance, fast water absorbency and good wicking properties [ 18 , 19 ]. Hemp is more water absorbent than cotton [ 20 ]. Bamboo bre or bamboo textile is another highly absorbent material. Bamboo bre is also more absorbent than cotton [ 21 ].
The cross-section of the bre is lled with numerous micro-holes and micro-gaps. Bamboo bres' cellulose composition consists of crystalline and hierarchal structures which differs from the other natural materials. Bamboo is also found to contain a unique anti-bacterial and bacteriostasis bio-agent called 'Bamboo Kun'. This feature of bamboo bre makes it useful for sanitary products, as it will not gather as much bacteria as other alternatives, when worn for extended periods. Bamboo bre appears to be an excellent alternative to SAP's, as it is highly absorbent, biodegradable, has excellent ventilation and several anti-bacterial properties. However, processing of bamboo bre and sealing it into a sanitary pad is expensive, which in turn increases the user cost. In view of that, direct usage of bamboo wadding fabric instead of bamboo bres was investigated in this current study. Bamboo wadding fabric has been used previously only inside quilts and children's coats.

Materials And Methodology
Four different kinds of natural biodegradable material namely (a) 100 % cotton terry cloth, (b) 100 % hemp cloth, (c) 100 % bamboo wadding and (d) 100 % linen were investigated in this study to nd out their respective absorptivity index. All the fabrics are commercially available in bulk off the shelf and procured accordingly. The fabrics were cut by hand to give them a rectangular shape and stacked to 1 cm thickness as shown in Fig. 1. Together with that, the absorbency of a regular, store-bought sanitary pad (1 cm thick) was investigated as a comparison for the other materials. To ensure reproducibility of the results, all the experiments were triplicated.
A gelatine solution was used to imitate the viscosity of menstrual uid to provide a more realistic experiment. The typical volume of menstrual uid lost during a monthly menstrual cycle is about 10-80 mL over eight days (average menstrual cycle). In present study, 20 mL of liquid (gelatine solution) was used to test the absorbency of these natural materials to ensure that the fabrics can retain more than one day's worth of menstrual uid. At rst, 10 g of gelatine was added into 300 ml of water and heated (60°C) with stirring until there were no remaining gelatine particles visible. The solution was then split up into 15 x 20 ml volumes for each fabric. The temperature of each solution was then checked to ensure the liquid was at room temperature (21°C) to maintain a constant gelatine solution viscosity, visually representative of menstrual uid that could remain across each test fabric. Then each of the test fabrics was weighed in precision lab-scale, placed into the container of the same size and 20 ml of the gelatine solution was poured. After 60 seconds, the fabric was removed from the container and weighed again. The absorptivity index (ratio of absorbed mass to dry weight) was calculated. An absorptivity index was used to ensure that the results could be comparable, as each fabric has a different dry weight, and were hence incomparable. Parallax and reading errors were reduced by setting each measuring cylinder down on a at surface and measuring the gelatine liquid from eye-level.
Random cross checks were conducted by a lab assistant. Table 1 shows the relevant data together with respective standard deviation from statistical analysis. For ease of comparison, absorptivity index of the materials was plotted as a bar graph and shown in Fig. 2. As seen in Table 1, cotton terry cloth had the lowest average absorptivity index (0.84 ± 0.15), even than that of linen (1.57 ± 0.16) and hemp (1.40 ± 0.17), which is contradictory with respect to the research reported in literature [ 22 , 23 ]. Bamboo wadding had the highest average absorptivity index (7.86 ± 1.01), followed by the Kimberly-Clark Kotex commercial sanitary pad (4.38 ± 0.02). The absorptivity index of bamboo wadding was almost twice that of the commercial sanitary pad.

Results
Bamboo wadding had the greatest mass of absorbed solution (19.69g ± 0.06) which was similar to the mass of absorbed solution of the Kotex commercial sanitary pad (19.49g ± 0.21), however the sanitary pad was 1.8x the starting dry weight of the 1 cm stacked bamboo wadding. Cotton terry cloth had the lowest mass of absorbed solution (6.67 ± 1.23), followed by hemp cloth (7.86 ± 0.97) and linen (10.26 ± 0.44).

Discussion
According to literature [ 24 ], bamboo bre was described as more absorbent than cotton, however this experiment revealed that bamboo bre in a non-woven wadding form was nine times more absorbent than cotton, and almost twice as absorbent as a standard sanitary pad.
The superior absorptivity of the bamboo wadding is due to the unique structure of the bamboo bre. Bamboo bres are composed of a different type of cellulose structure, which differs from that of the other materials. While all cellulose sugar molecules can break a liquid's surface tension and allow the liquid to absorb into spaces between bres, and into bres themselves, bamboo cellulose's crystalline and hierarchal structure differs, making the fabric more absorbent. Bamboo has good overall moisture management capability, which classi es the material as water penetration fabrics with small spreading area [ 25 ]. A recent study found that bamboo bre as an absorbent core in a traditional sanitary napkin format absorbs and wicks water 3-4 times better than cotton and reduces odour as the bre is lled with multiple micro-holes and micro-gaps [ 26 ]. Thus, the use of bamboo bres as a core of sanitary pads is a good alternative compared to SAP and moreover, it is biodegradable in nature. In addition, bamboo bre in wadding form, as investigated in present study, is more convenient to use, and lower in cost in comparison with bamboo bre embedded commercial sanitary pads. cellulose bamboo bres which are spun into yarns and given the shape of bamboo wadding [ 29 ]. For sanitary pad production the bamboo bres are then covered in a polythene and non-woven sheet and released for cutting. The hygienic napkins are then sealed with adhesive and perfumed before sending for packing. However, this approach became commercially unviable in practice due to the complexity of the process as well as initial investment [ 30 , 31 ].
Having said that, an alternative of large-scale commercialization is the small-scale handicraft-based approach involving the people who are going to use it. In this approach, non-governmental organizations (NGOs) may take the lead, as NGOs in low-and middle-income countries are playing a signi cant role in socio-economic developments. For example, Goonj [ 32 ], an Indian NGO in New Delhi, currently collect urban surplus fabrics, then wash, dry and cut them into pads which are packed and distributed via partner grassroots NGOs. It is possible to involve such NGOs to distribute low-cost bamboo wadding to replace less absorbent surplus fabrics, with users hand cutting the fabric to give the required shape. It is also possible to involve such NGOs to train-up local communities to make bamboo wadding from plants. This will reduce the cost, make it readily available among school girls and women and could have a signi cant transformative effect. Moreover, bamboo wadding is re-usable in nature.

Conclusion
In the present research, absorptivity index of a number of biodegradable materials was investigated with gelatine solution and compared against a commercial sanitary pad. It was found that bamboo wadding was the most absorbent natural material in comparison to hemp cloth, linen and cotton terry cloth. Being nearly twice as absorbent as a commercial sanitary pad, bamboo wadding appears to be the most suitable material for the use of sanitary products as it is extremely absorbent, affordable, lightweight, biodegradable, has no detrimental effects on the user or the environment. This experiment is exploratory and requires further replication and investigation but is a promising start in this eld.

Abbreviations
NGO -Non-governmental organization Authors' contributions JF completed the experiment, analysed and interpreted the results, drafted the background and results and was a major contributor to writing the paper. JF contributed revisions to subsequent drafts.
PM added concepts to the background, elements of generalisability and the link between bamboo plants and converting them to fabric to the discussion content of the paper. PM was also a contributor to writing overall revisions to the paper.