Drivers of menstrual material disposal and washing practices: A systematic review

Background Disposal and washing facilities and services for menstrual materials are often designed based upon technical specifications rather than an in-depth understanding of what drives peoples’ choices of practices. Objectives and data sources This systematic review identified and summarised the main behavioural drivers pertaining to the choice of disposal and washing practices of menstrual materials through the thematic content analysis and study appraisal of 82 publications (80 studies) on menstrual health and hygiene published since 1999, reporting the outcomes of primary research across 26 countries. Results Disposal and washing behaviours are primarily driven by the physical state of sanitation facilities; however, this is intrinsically linked to taboos surrounding and knowledge of menstruation. Implications Using reasons given for disposal and washing practices by menstruators or those who know them well, or inferred by authors of the reviewed studies, we identify the key considerations needed to design facilities and services which best suit the desired behaviours of both planners and those who menstruate. Inclusivity The term menstruators is used throughout to encompass all those mentioned in the studies reviewed (girls and women); although no studies explicitly stated including non-binary or transgender participants, this review uses inclusive language that represents the spectrum of genders that may experience menstruation. Registration The review protocol is registered on PROSPERO: 42019140029.


Introduction
Menstrual health and hygiene (MHH) are an integral part of public health, recognized by an increase in research on this topic in the past decade [e.g. 1,2], and the recent definition of menstrual health [3]. Within the MHH space there has been a lot of research into the provision of menstrual materials, and subsequent interventions that provide those who menstruate with both reusable and disposable materials [4][5][6]. However, there has been less research into what happens once these materials have been used; the full lifecycle of these materials has often not been documented. Understanding the full lifecycle of menstrual materials is especially important for those designing the infrastructure of water, sanitation and hygiene (WASH) programs, including, but not limited to, toilets, bathing facilities, washing and drying facilities, incinerators, and solid waste management services. Water, sanitation and hygiene facilities need to be technically and socially appropriate to allow people to change and dispose of menstrual materials safely for them, the associated infrastructural systems and the environment. Disposal choices directly affect the functioning of sanitation systems; if materials are discarded in toilets or pit latrines, they can create blockages which reduce functionality of a system [7]. Disposal and washing practices can also have adverse health effects on users, for example, if there are no spaces for drying reusable materials, it is possible that infections could manifest if materials are used before they are dried properly [8].
Currently, the drivers behind menstruators' choice of disposal and washing practices are often not documented and rarely considered when WASH facilities are designed. For example, although it alludes to the need for 'cultural considerations' when designing facilities, the International Standard on Non-Sewered Sanitation requires technology developers to provide users with instructions on how to dispose of their menstrual materials so as to protect the functioning of the technology, but this does not necessarily consider the reasons why a user may choose to flush materials despite knowing that it may harm the infrastructure [9]. This views users through a deficit lens [10], it assumes that if only they knew better they would change their behaviour. But WASH behaviours are not always driven by possessing the appropriate 'knowledge', for example, people may have been taught that it is unsafe to practice open defecation but choose to do so for reasons of convenience, pride and mental well-being [11]. Such disconnects between 'knowledge' and 'action' are why the field of WASH behaviour change scholarship exists [12].
Two systematic reviews have been published compiling the methods of menstrual disposal used in low and middle income countries [13,14], but neither thoroughly investigates why users practice these behaviours. A recent critical review of 'unflushable' objects entering waterborne sewerage highlights the lack of research into the drivers behind user decisions to dispose of non-biodegradable materials in toilets around the world [15]. No reviews have been published on menstrual material washing practices.
To better design WASH systems that meet the needs of those who menstruate it is important to understand what disposal and washing practices are currently used, but more importantly, why: if WASH professionals can understand what drives washing and disposal methods in different contexts, they can design technically robust systems that those who menstruate want to use. To address this, we systematically investigated the extant peer-reviewed literature on menstrual disposal and washing practices so as to determine: 1) What drives the behaviours of those who menstruate when deciding on a method of disposal or washing of used menstrual products?; 2) Are there differences in behavioural drivers and practices between low, middle and high income economies?; 3) If MHH programming is to be socially, environmentally, economically and technically sustainable, how does it need to engage with the drivers of behaviour around disposal and washing?

Search strategy
A systematic search of peer-reviewed literature was conducted according to the PRISMA guidelines [17] (Fig 1) and included documents published since 1999, to ensure that findings were relevant to current disposal and washing practices.
Topics to be searched for in the documents included: solid waste disposal; menstrual waste disposal; health effects regarding disposal and material usage, and factors affecting disposal routes (Table 1). Searching was undertaken in eight databases in June 2019 and updated in June 2021.
This yielded the following results for initial screening: Scopus (8,367), Web of Science (5,050), EBSCO (consisting of CINAHL, GreenFILE, Social Work Abstracts, Child Development & Adolescent Studies) (1,681), MEDLINE (5,005) and Proquest Dissertations and theses (440). We also hand-searched the bibliographies of the two existing reviews on low/middle income country menstrual material disposal methods [13,14].
After removing duplicates, titles and/or abstracts of 14,198 publications were screened against Criteria 1 (primarily about menstruation or sexual and reproductive health), followed by the full-text screening of 948 publications against Criteria 2 (published post-1999 and discusses behaviours post-1999; in English or has an English translation available; discusses menstrual material disposal, washing, drying and/or reuse and gives reasons for these behaviours). This led to the inclusion of 82 publications (80 studies) ( Table 2 provides a summary of the included studies, for full details of each see S1 Table). Grey literature was not searched as the themes which arose from the peer-reviewed publications reached saturation.

Quality appraisal
Included studies were assessed on their level of trustworthiness and relevance by adapting the method of Rees et al [100] to be applicable to both quantitative and qualitative MHH studies. The assessment of trustworthiness was dependant on the sampling, data collection and analysis, and interpretation of data; this yielded high, medium, and low ratings. Relevance related to the proportion of the paper dedicated to menstrual material disposal or washing, whether confidentiality had been assured and appropriate consent obtained, and who gave the reasons for behaviours; this yielded high, medium, and low ratings (for full details of the quality appraisal of each study, see S2 Table). We considered studies which took a social constructivist approach to understand drivers of menstrual disposal and washing, evidenced by the experiences of menstruators, to be of higher relevance than those which presented less direct evidence and tended along positivist epistemological lines. Considering the trustworthiness and relevance of studies allowed us to weight themes more heavily where they were results of robust research, particularly where the reasons for disposal and washing behaviours were given by those who menstruate themselves.

Thematic content analysis
After reviewing the full texts of each publication, deductive and inductive coding was undertaken using NVivo 12 [101]: 1. Examples of practices were deductively coded as "intentional disposal" or "washing drying or reuse".
2. Axial coding was conducted to identify the drivers behind each practice (see Table 3 for codebook and coding frequency). This led to an understanding of the influence of physical and social drivers on menstrual material disposal and washing practices and how these must be considered by those planning WASH facilities.
3. Publications were also classified demographically in order to understand the study context (Tables 2 and S1).
A conceptual model was developed to understand the breadth of reasoning behind disposal and washing practices.

PLOS ONE
Drivers of menstrual material disposal and washing practices: A systematic review

Results
Publications detailed studies in low income economies (17 studies), lower middle income economies (58 studies), upper-middle income economies (5 studies), high income economies (3 studies), and displacement camps (3 studies) (as defined by World Bank in 2020 [102]) (Tables 2 and S1). There was a skew towards girls' (<18 years old) experiences over women's experiences (58 instances vs. 29 instances). There were no studies which detailed the experiences of those who identify as trans-men or gender non-binary. 49 studies were rated as high trustworthiness, 30 medium trustworthiness and 1 low trustworthiness. High trustworthiness papers were characterised by having more than 50 participants, a clear analysis description, and supportive quotes that were clearly distinguishable between participants. 26 studies were considered of high relevance to this review, 46 medium relevance and 8 low relevance. High relevance studies tended to have a high proportion of the paper discussing findings relevant to disposal and washing of menstrual materials, evidence of behavioural drivers as stated by menstruators themselves, and consent and confidentiality measures stated clearly. Lower relevance studies only briefly mentioned disposal and washing behaviours and/or presented the reasons for behaviours mostly from author inferences, rather than given by menstruators themselves. In 29 studies, reasons for disposal and washing practise were given by menstruators alone, in 23 reasons were given solely by authors, and in 28 there was a mixture of authors' reasoning and menstruators' reasoning. The reasons given for disposal and washing practices for each study are detailed in S1 Table and a summary of the frequency of reasons is detailed in Table 3. Illustrative examples of the drivers of disposal and washing behaviours are provided in S3 Table.

Reasoning behind behaviour
When investigating the reasoning behind menstruators' choice to use certain disposal and washing practices, the predominant factor was the availability of appropriate WASH facilities (where 'appropriateness' was defined by users). Of the 80 studies, 56 mentioned that the reason for the disposal or washing practice directly related to the state of the facilities used to manage menstruation, 52 the physical needs of the individual, and 42 the social perceptions of the facility according to individuals. There were 13 instances of menstruators stating lack of knowledge as a reason that affected their behaviour, as they stated they were unsure what was supposed to be done after menstrual materials had been used. Menstrual stigma and taboos were stated in 55 papers as a reason influencing disposal and washing practices.
Where the physical state of WASH infrastructure was mentioned, it related to the quantity of available and physically functional toilets/latrines [

Discussion
There are three main drivers of menstrual disposal and washing behaviour, and they can be independent or influenced by one another. They can be standalone, for example, there may be no bin within the WASH facility so a menstruator cannot dispose of materials into a receptacle, the menstruator may not have been taught how to dispose of used materials so does not know what to do, or the menstruator may have been taught that they must not incinerate materials lest evil spirits negatively affect their health. However, the reasons for disposal and washing menstrual materials can also be multi-faceted. In some instances all three combine to influence behaviour: for example, a menstruator may not have been taught how to dispose of materials, feel uncomfortable openly discussing disposal options due to menstrual stigma and may not know what facilities are needed or available, or how to change facilities or practices to make them more appropriate.

Understanding the drivers
The state of WASH facilities was the predominant driver in 57 studies. This included the physical needs and social perceptions of menstruators, but often also incorporated menstrual taboos and social stigma, for example, just because facilities existed, and were technically 'appropriate', did not mean they were used. Crofts and Fisher noted that incinerators had been constructed in five of the 18 schools where interviews took place, so there was a physically functioning menstrual disposal option present, however the actual usage was low [36]. The incinerators had been built on the opposite side of the school to the toilets, so students did not want to be seen entering the incinerator building, and even when disposal buckets were provided in toilets, there was no management in place to take waste from toilets to the incinerator [36]. So, although there were physically appropriate disposal facilities, due to stigma around being seen holding or disposing of used materials, the disposal facility was not used. The theme of menstruators not wanting to be seen disposing or washing their used materials was driven by two emotions: being embarrassed and/or worried (35 studies), or fearing that they would be seen, and what would happen if they were seen (13 studies).
Beyond embarrassment, fear of being seen disposing or washing was a recurring theme [34,35,40,59,61,68,69,78,80,81,83,87,91]. This related to favouring methods of disposal or washing that were deemed secretive or hidden in order to limit their menstrual status being exposed [34,47,60,68,78,91]. Within this theme, menstruators noted they wanted to hide their used materials so that animals, specifically dogs, couldn't find their materials and expose their status [20, 41,60,70,82,83,87]. They especially wanted to hide their status from males, specifically fathers and fathers-in-law [40,47,60,61,68,80]. This was in part due to fears of unwanted sexual advance [35], abuse and violence [19, 69,81] and being forced to leave school at menarche so as to get married [59,68]. Other fears to use disposal methods stemmed from young menstruators being afraid that having a period was a "punishment from God," so hiding materials so that their parents would not find out [35], or that if seen, they would risk "infertility" or "being cursed" [87].
Cultural knowledge also influenced the choices that drove disposal and washing behaviours. For example, incinerators are often used for menstrual waste [35], and although they may be technically appropriate, in some cultures there are negative connotations surrounding the burning of menstrual blood [84] or instances where menstrual blood is kept to be used for ritual purposes [22,93]. These feelings were highlighted in Karibu et al's Nigerian study where "38.0% stated that they chose what they considered to be the best disposal method to ensure protection from metaphysical forces. . . [and]. . . 2.4% said they chose their method to avoid evil people" [55].

Biased menstrual choices
When examining the language used in the papers, it became apparent that there is a bias in the way some disposal and washing methods, as well as menstrual materials themselves, were written about by the authors, most of whom are WASH researchers or practitioners. There has been a tendency to write about material use or disposal and washing behaviours with a view that some are superior to others, even where there is limited health or technical evidence to support this. Bias was highlighted in statements such as 'only x % of interviewees use sanitary pads' (emphasis added, [42,90,91,94]). Although sometimes the bias was used in ways to highlight unhygienic practices, for example "only a few used any kind of antiseptic soap or liquid [to wash their pads]" [24] it still singled out and shamed individuals rather than considering the myriad of factors contributing to their behaviours and the suitability of their washing and disposal practices to their personal circumstances. A similar bias occurs in Community Led Total Sanitation and some sanitation marketing programmes, where people are identified, and often shamed for their behaviours, regardless of their ability to change a situation, whether that be due to insufficient funds, lack of access to different options, or personal behavioural and cultural choices [103,104].
It must be understood that there are many reasons for choosing specific menstrual materials and disposal and washing behaviours, and that writing in a style that judges choices may vilify individuals, reinforce harmful taboos, and not succeed in changing behaviours to those which may improve the wellbeing of those who menstruate. WASH practitioners who read such studies may develop their own biases against behaviours which are in fact appropriate to local contexts and low risk to menstruators' health. For example, there has been a frequent bias in the WASH literature and programming against the use of 'cloths' or 'rags', often conflated as one. However, this does not consider that a cleaned and dried reusable pad or cloth may be just as hygienic and clean as a disposable pad, whilst a dirty rag poses obvious hygiene risks. In Chakravarty et al's paper, this infiltrated bias had directly affected material use, with one menstruator stating, "here we use only pads, we now [after MHH programming] realise how unhygienic it is to use cloth" [28]. There are several factors that contribute to menstrual material choice including, but not limited to, the preferences of and options for disposal and washing available to those who menstruate.

Implications for WASH programming
When programming for MHH and the associated WASH facilities, WASH professionals must consider not just preferences for menstrual material choice, technologies, and disposal and washing practices, but also the physical and social perceptions of menstruators, the availability and form of knowledge in the cultural context, and the menstrual taboos and social stigma that continue to impact on those who menstruate across the globe. The focus of MHH programming must be to improve the physical, mental, and social well-being of menstruators within their own contexts (the very definition of menstrual health [3]), not to promote specific WASH facilities or technologies preferred by implementers; considering the drivers of menstrual behaviour throughout the lifecycle of materials will assist in improved experiences for menstruators.

Limitations
This was a global review of published data. We originally aimed to highlight and understand the disposal and washing practices of those who menstruate around the world, with no geographical or economic limitations. However, of the 80 studies included in this review, only three were from high-income economies and another five were from upper-middle income economies. This was surprising given the media coverage in recent years surrounding the 'fatbergs' negatively impacting the functionality of sewers in cities in higher income countries [105]. Such fatbergs are attributed largely to the flushing of menstrual materials and wet wipes. Water utilities have put out calls to stop such behaviour [106], but, similar to the way users are often encouraged to change their menstrual material disposal behaviours in LMICs through the imparting of knowledge, these campaigns tend to assume that people flush these items because they do not know how harmful the practice is. Very limited research has investigated the behavioural drivers of menstrual material disposal in higher income economies.
Thus, although this study set out to reflect worldwide practices, due to the lack of data from higher income economies, this study is not representative of global practices. There were parallels within the small amount of high/upper-middle income economy data that showed similar themes and reasoning behind drivers of behaviour to lower-middle and low income economices, but due to the low proportion of these papers, we cannot determine with certainty whether these behaviours are universal. We join with Alda-Vidal et al. [15] in calling for further social science research on the clear gap of higher income economy data, and suggest it will be of particular interest in areas where fatbergs are impacting on WASH systems.

Conclusion
This review demonstrates the complex nature of washing and disposal behaviours related to menstruation. Behaviours are often not solely reliant on one factor, but several interrelated considerations. It is the first review that has aimed at understanding why people choose to engage in various menstrual material disposal and washing practices.
WASH professionals and other implementers of menstrual disposal and washing facilities and services need to ensure that disposal and washing options are appropriate for their context. Even when facilities are installed and accessible, if considered inappropriate they will not be used [36,57,71]. In addition, educational policy needs to allow for the teaching of menstruation in a scientific, judgement-free zone, where those who menstruate feel comfortable to learn without the fear of embarrassment. Many young menstruators, and teachers in some instances, were highlighted as not having sufficient knowledge about menstruation and menstrual management, or were biased to certain materials and practices, with a specific emphasis on missing disposal information [21,24,30]. By creating a safe space to facilitate discussion, young menstruators will be able to learn more about this taboo topic.
Menstrual material disposal and washing is an area that is poorly understood globally, and as the first systematic review compiling these behaviours, this paper begins to provide clarity in an under-researched area. By exploring the drivers of disposal and washing behaviours, we demonstrate the interfaces between facilities, knowledge and taboos d. It is clearly important to integrate these aspects into the planning and provision of infrastructure systems that interface with MHH in order to provide accessible and appropriate facilities for all.