Knowledge, Attitudes And Disposal Practices For Unused Medicines Amongst Adult Residents Of Bloemfontein, South Africa

Abstract

Background

In South Africa, medicine disposal is regulated by the Medicines and Related Substances Act 101 of 1965. Despite regulatory provisions, the presence of pharmaceuticals in the environment is a growing concern. This study aims to assess the knowledge, attitudes, and practices toward the disposal of unused and expired medicines among residents in Bloemfontein, Free State.

Methods

This was a descriptive, quantitative, and cross-sectional study involving 394 Bloemfontein residents. During 2024 a self-administered questionnaire was distributed to adult participants. Multiple linear regression was used to identify sociodemographic determinants of knowledge, attitudes and practices. The Spearman correlation test was employed to determine correlations between KAP among residents.

Results

Multiple linear regression analysis revealed gender (β = 0.25, R² = 0.01), employment status (β = 0.48, R² = 0.04), usage of private health-care systems (β = 0.16, R² = 0.04), and health-care worker status (β = −0.89, R² = 0.02) were significantly associated (p ≤ 0.05) with a higher knowledge score. Health-care workers (β = −0.01, R² = 0.01) were associated with a higher attitude score. Gender (β = 0.15, R² = 0.02), level of education (β = 0.09, R² = 0.01), and being a health-care worker (β = −0.47, R² = 0.05) were predictors of residents’ medicine disposal practices. The Spearman correlation test revealed a positive relationship (r = 0.14, n = 394, p < 0.05) between residents’ knowledge and attitudes towards appropriate disposal practices.

Conclusion

Significant differences in the KAP across sociodemographic variables among residents were found. Health-care workers distinguished themselves above non-health-care workers in all factors. The results of this study indicate poor knowledge, positive attitudes and inappropriate medication disposal practices amongst Bloemfontein residents. These findings and the potential effects of resident’s actions require action, through the creation of awareness, holding pharmacists more accountable and additional policy changes.

Introduction

The effect of household medicine disposal has been reported as a global problem.1 The presence of pharmaceuticals in the environment is attributed not only to their use but also to their incorrect disposal. Despite this, there appears to be no coordinated international response to this environmental and public health concern.2 South Africa has the largest pharmaceutical market in Africa, estimated at over $3.9 billion, trailed by Egypt at $2.6 billion, with annual prescription medicine, innovator drug, and over-the-counter medicine revenue growing.3,4 This increase in the consumption of medicine is a cause for concern due to the potential increase of medicine contamination caused by inappropriate medicine disposal and its contribution to the degradation of the environment and threat to public health.5

South Africa has incorporated environmental protection into its legal framework, with pro-environmental rights embedded in the Constitution and various acts and policies that regulate medicine disposal. Specifically, the Medicines and Related Substances Act 101 of 1965, which states that disposal must be regulated at a municipal level. This is only addressed by the KwaZulu-Natal Province which specifies that medicines should not be discarded in municipal waste or sewage systems.6–8 This is comparable to other nations that have set forth similar policies. Nevertheless, despite these regulations and the ongoing increase in medicine use, there remains limited knowledge, low awareness, and poor consumer practice regarding proper medicine disposal.9

Current Knowledge, Attitudes and Practices

The safe disposal of unused and expired medicines remains a persistent public health and environmental concern. Numerous studies indicate that patients’ knowledge of appropriate disposal methods is inadequate across diverse settings. In India, for example, 65.5% of participants regarded disposal of medicines through municipal waste systems as acceptable,10 while in Nepal, 65.2% of respondents reported being unaware of any established safe disposal procedures.11 Comparable findings have been documented across several African countries, including Zambia, Liberia, and Ethiopia, where most participants demonstrated limited awareness of recommended pharmaceutical disposal practices.12–14

South African evidence reflects similar deficiencies. Despite a comparatively well-structured health system, available studies consistently report that fewer than 45% of respondents possess correct knowledge of appropriate medicine disposal methods.9,15,16 These findings indicate that gaps in public awareness are widespread and not confined to regions with weaker health infrastructure.

Although knowledge is limited, studies from several developing countries suggest that public attitudes toward safe medicine disposal are generally favorable. In Peru, a study conducted in San Juan de Miraflores found that 93.25% of participants expressed positive attitudes toward appropriate household medicine disposal,17 while research in India reported that 80% of participants held similarly favourable views.18 In East Africa, the majority of respondents agreed that unused and expired medicines should be disposed of appropriately because of associated health risks, with many also expressing concern about the lack of adequate information on proper disposal.19 A study from north-western Nigeria yielded comparable results: 86.2% of participants recognized potential health hazards, and 95.3% indicated willingness to comply with recommended disposal practices.20

In contrast, no South African study to date has exclusively examined public attitudes toward medicine disposal. Related research, however, provides partial insight. One study, conducted in Cape Town, reported that 76.5% of participants would be willing to return unused medicines if requested, although practical factors, such as time, influenced their willingness.16 Another study conducted in Tshwane documented markedly lower willingness, with only 34.4% of participants indicating a desire to dispose of their unused or expired medicines.9 The lack of focus on additional attitude variables underscores the need for research on attitudes in the South African context.

Despite variations in attitudes, empirical evidence from several low- and middle-income countries reveals that disposal practices remain largely inconsistent with recommended guidelines. Studies from Afghanistan, Pakistan, Tanzania and Ghana show widespread use of municipal waste or sewage systems for disposal.21–24 Such behaviors pose risks of environmental contamination and contribute to inappropriate pharmaceutical exposure.

South African studies demonstrate comparable trends. Research from Tshwane in 2022 found that 55% of residents disposed of medicines through municipal waste or sewage systems.9 During 2017, in Johannesburg, 76.2% of households discarded medicines, predominantly via municipal waste or flushing through sanitary systems.15 Correspondingly, a study in KwaZulu-Natal conducted in 2020 reported that 80% of participants disposed of medicines through sewage or municipal waste.25 These findings reflect ongoing challenges in public education and waste-management systems.

As described above, persistent deficiencies in knowledge, variations in attitudes, and continued reliance on unsafe disposal practices underscore the need for further research, particularly within South Africa. Few studies globally, and even fewer locally, have examined sociodemographic determinants influencing knowledge, attitudes, and practices (KAP) related to the disposal of unused and expired medicines. Understanding these determinants is essential for developing targeted interventions and strengthening public health strategies.

Objectives and Rationale

To our knowledge, no study has focused on measuring attitudes towards medical waste disposal in South Africa. In addition to this, most of the mentioned South African studies did not report the influence of sociodemographic variables on KAP of medicine disposal. Adding to this point, very few studies, globally and locally, have examined their data for sociodemographic predictors of appropriate KAP regarding the disposal of unused and expired medicines.

This study fills that gap by identifying sociodemographic determinants and predictors of KAP regarding the disposal of unused medicines in a developing country such as South Africa.

Materials and Methods

Study Design

A descriptive, cross-sectional study was conducted in which information on patients’ knowledge, attitudes, and practices regarding the disposal of unused and expired medicines was collected through a distributed survey. This information was analyzed and reported on.

Study Population and Sampling

Bloemfontein is the capital city of the Free State province. The population is estimated at 214,940 people, of whom 52.5% are female. The main languages spoken include Sesotho, Afrikaans, and English. The population is relatively young, with the majority of residents under the age of 40.26

Bloemfontein, reported by South African Cities Network (2014) as having a “lack of sufficient resources and support in the municipal waste department”27 Bloemfontein has also been reported by Lion (2023) as “currently struggling with service delivery” in terms of waste collection and removal.28 In terms of pharmaceutical services provided, the city of Bloemfontein is described as lacking in public health sector pharmacy personnel.29 With these worrying factors as a backdrop, this research aimed to provide valuable insight into the knowledge, attitudes, and practices of appropriate household medicine disposal in Bloemfontein.

Sampling was based on the adult (18 or older) population of medicine consumers in the city of Bloemfontein, Free State, South Africa. To achieve the desired representative sample, non-probability convenience sampling was employed among the 214940 residents.

As the number of adult residents in Bloemfontein who keep or dispose of unused and expired medicines is unknown, Cochran’s formula, specifically, was employed.30 Where, n₀ represents the required sample size. Z² equated to a 95% confidence level provides a Z value of 1.96, as per the set standard normal distribution. The value p represents the population proportion who keep or dispose of unused and expired medicines (assumed to be 0.50 since this would provide the maximum sample size required). The value q equated to 1-p. Lastly, e was equivalent to the desired precision level of 5% (0.05). This yielded a required sample size of 384.

Criteria for inclusion in the study included the following: participants had to consent to participate, were over the age of 18, resided in Bloemfontein at the time the study was conducted, and, lastly, those who kept unused or expired medicines at their place of residence.

Data Collection Instrument

The data collection instrument used was a self-administered questionnaire. The validated instrument was adapted from previous studies.31,32 The chosen survey included minor additions to the sociodemographic information section to provide a more complete background of the participants. The English collection instrument used has been included as Supplementary File 1.

The questionnaire employed consisted of four sections. Section A consisted of nine questions focusing on collecting sociodemographic information. Section B, five questions pertaining to the participant’s knowledge of medicine disposal. Participants were given the choice of answering “yes” or “no” to the first four questions, with the last question testing an opinion, presented as a multiple-choice question. Section C included four questions on attitudes toward medical waste disposal. Participants were able to answer, “strongly agree”, “agree”, choose to remain “neutral”, “disagree”, “disagree”, or lastly, “strongly disagree”.

Lastly, Section D included five questions pertaining to the participant’s practices regarding medicine disposal. Participants could answer “yes” or “no” to the first question and choose their method of medicine disposal through multiple-choice options in the next three questions.

Data Collection

Data collection took place over three months: April to July 2024, at major strategic points throughout Bloemfontein. A pilot-tested survey was conducted with ≈10% of the final sample (n=40) to ensure the validity of the data collection tool and processes. Shopping centres were chosen as study sites and were identified based on their geographical location, being in different non-adjacent suburbs, throughout the city and the presence of a pharmacy. Thereafter, the management teams of the shopping centres were contacted. All study sites were approached for permission to administer surveys; of those for which permission was granted, data collection took place accordingly.

Visitors and employees within the study sites, including Mimosa Mall and The Towers Shopping Centre, were targeted for administration of the survey. Potential participants were approached by the researcher to complete the survey in approved study sites in Bloemfontein. Simultaneously, a QR code, which participants could use to access the digital survey, was presented to the participant when engaged, and displayed at the approved study sites’ notice boards. Social media services such as WhatsApp were also used to distribute the QR code to groups exclusive to Bloemfontein residents, with the permission of group administrators.

In addition, a physical version of the survey was offered to the potential participant if required. If participants chose to make use of the electronic survey and did not complete the digital survey, they were contacted with their requested telephone numbers, which allowed the researcher to remind these individuals to complete the survey two weeks after the initial prompt. All three participants who opted for this method were successfully contacted through a telephonic text message. This was verified by a reply.

Reliability

The reliability of this study was ensured through the use of a validated data collection tool. The validated tool questionnaire was previously, adapted and used to measure the same variables in other studies.14,19,33 A pilot study was conducted with a sample greater than ten percent of the final sample (n=40) used to further enhance reliability. Upon completion of the pilot study, the questionnaire was reviewed with input from pilot study participants before implementation in the main study.

A test for the reliability of the employed data collection tool resulted in a Cronbach’s Alpha value of 0.65. While 0.7 is generally regarded as acceptable, a similar study deemed this achieved level as a minimum acceptable result with regard to internal consistency.34 Translations of the survey into Sesotho and Afrikaans were performed by professionals who had studied the respective languages at a tertiary level. These translations were then translated back to English by healthcare workers who were fluent in the respective languages to ensure consistency and reliability.

To further ensure reliability, the accurate completion of the surveys was monitored as far as possible during administration to participants. Responses were screened for completeness in order to reduce response errors. To ensure the reliability of captured data, input data was double-checked before moving on to the next entry.

Validity

Internal validity was provided by the multichannel questionnaire distribution method, which was opted for. This allowed for a greater reach for the survey employed, which assisted in minimizing the chance of coverage errors. Additionally, internal validity was further improved by performing a pilot test whereby the survey was distributed to 40 individuals, greater than the desired ten percent, to pre-test the study. These individuals did not participate in the main study. This helped assess the survey for flaws before distribution in the main study.

Bias

Minimisation of bias was achieved through a number of methods. Sampling bias, such as under coverage bias, was best mitigated by employing two different data-capturing sites for physical distribution. In addition, the survey was distributed via social media. Measurement bias was avoided by examining participants’ responses to ensure that no raw data was omitted or recorded incorrectly. If so, these responses were excluded, and a new sample was generated in their place. Acquiescence bias was avoided as the chosen survey contained only closed questions. The chosen survey was short in length (eleven minutes) and contained 22 questions of various types (Yes or no, Multiple choice and a Likert scale) in order to minimise respondent fatigue. Participants were not informed of the study’s aims to prevent them from becoming aware of the research expectations.

Data Analysis

The secured data was analyzed with the assistance of a biostatistician using International Business Machines (IBM) Statistical Package for Social Sciences (SPSS) version 29 and Microsoft Excel 365.

Socio-demographic data were expressed in frequencies and percentages. Knowledge scores ranged from zero to four points, reflecting correct responses to four key questions in Section B. A score of two or less was considered poor, three- moderate, four or above was considered good. Attitude scores ranged from four to 20 points, based on summing the Likert-scale responses from four questions in Section C. Six points or less was considered poor, seven to twelve was considered neutral, and thirteen and above was considered positive. Practice scores ranged from zero to four points, derived from four questions in Section D. A score of two or less was considered poor, three- moderate, four or above was considered good. Two questions were excluded from scoring: one in the knowledge section, capturing opinions on medicine disposal methods, and one in the practices section, asking about reasons for retaining unused medicines.

Each section was scored using a simple points system. For questions with one or more correct options, participants received 1 point for a correct answer and 0 points for an incorrect answer. In Section C (attitudes), which used a five-point Likert scale, responses were scored as follows: “strongly disagree” = 1 point, “disagree” = 2 points, “neutral” = 3 points, “agree” = 4 points, and “strongly agree” = 5 points.

A One-sample Kolmogorov–Smirnov test was performed to determine and confirm a nonparametric population distribution. Mean scores of KAPs were compared using a Mann–Whitney U-test (Where only two outcomes were permitted) and the Kruskal–Wallis H-test (Where three or more possible outcomes were permitted). Multiple linear regression was used to identify the socio-demographic determinants of participants’ knowledge, attitudes, and practices. Spearman correlation test was used to determine any correlations between knowledge, attitudes and practices. In this study, p ≤ 0.05 was considered significant. All data obtained from the survey and the data capture were kept on an encrypted external storage medium.

Ethical Considerations

Ethical clearance was granted from Turfloop Research Ethics Committee through obtaining an ethics clearance certificate under the project number: TREC/1775/2023: PG. In addition, this study complied with the Declaration of Helsinki.

Informed consent was obtained from each participant prior to their participation in the survey. This was done to ensure compliance with the Protection of Personal Information Act of 2013.35 Confidentiality was ensured by not disclosing any of the respondents’ information or sharing it with any individual not involved in the research project. Anonymity was ensured by not using participants’ names when capturing data. Instead, a unique study code was used in order to avoid defining or providing any identifying characteristics of participants. Participants were informed that their participation was voluntary. The participants chose to participate in the survey and could withdraw at any time.

Results

Socio-Demographic Characteristics and KAP Scores

A total of 396 Surveys were collected and included in this study. The mean age of the respondents was 38.2 years within a 95% confidence interval (CI) [37.42, 39.47]. 260 achieved some form of tertiary education (66.0%), and 212 made use of the public healthcare system (55.2%). In addition, 37 respondents reported health-care workers (9.4%) and 147 participants reported they had a health-care worker in the family (34.8%). This sociodemographic information is summarized in Table 1.

Table 1.

Sociodemographic Information of Bloemfontein Residents (n=394) (June 2024)

Sociodemographic Variable		Number of Participants (n=394)	Percentage (%)
Gender	Female	240	60.9
	Male	154	39.1
Age	18-30	116	29.4
	31-50	216	54.8
	51 and over	62	15.7
Highest Level of education completed	Primary School	11	2.8
	High School	123	31.2
	Tertiary	260	66.0
Employment status	Employed	287	72.8
	Studying	43	11.0
	Unemployed or retired	64	16.2
Usage of the public health system	Yes	212	55.2
	No	182	44.8
Net Income per month (in South African Rands)	Up to R 10,000	171	43.4
	R10 001 to R 20,000	117	29.7
	Over R 20,000	106	26.9
Are You a Health-care worker?	Yes	37	9.4
	No	357	90.6
Is there a Health-care worker in Your family?	Yes	137	34.8
	No	257	65.2

Total Knowledge, Predictors, and Individual Question Scores per Socio-Demographic Factor

The overall average knowledge score, out of four, was 1.87. This overall score indicated moderate knowledge of medical waste disposal amongst the residents of Bloemfontein. Table 2 summarizes the results concerning knowledge for each sociodemographic factor.

Table 2.

Bloemfontein Residents’ Knowledge Scores of Unused and Expired Medicine Disposal by Socio-Demographic Variable (June 2024) (n=394)

Socio-Demographic Characteristics`		Total Knowledge		Awareness of Medicine Waste		Informed of Safe and Appropriate Medicine Disposal		Ever Read Medicine Disposal Instructions		Improper Disposal of Medicines Affects the Environment and Public Health
		Mean (SD)	p-value	Mean (SD)	p-value	Mean (SD)	p-value	Mean (SD)	p-value	Mean (SD)	p-value
Gender	Female	1. 97 (1.12)	0.01*	0.58 (0.50)	0.25	0.29 (0.46)	0.69	0.27 (0.45)	0.70	0.83 (0.38)	0.00*
	Male	1.71 (1.18)		0.52 (0.50)		0.27 (0.45)		0.25 (0.44)		0.67 (0.47)
Age	18-30	1.82 (1.05)	0.62	0.45 (0.50)	0.02*	0.24 (0.43)	0.37	0.27 (0.44)	0.56	0.86 (0.35)	0.00*
	31-50	1.92 (1.14)		0.59 (049).		0.29 (0.46)		0.28 (0.45)		0.76 (0.43)
	51 and over	1.79 (1.32)		0.65 (0.48)		0.34 (0.48)		0.21 (0.41)		0.60 (0.50)
Highest Level of Education	No formal High School Education	1.64 (1.21)	0.24	0.73 (0.47)	0.36	0.27 (0.47)	0.76	0.18 (0.41)	0.53	0.45 (0.52)	0.01*
	High School	1.73 (1.10)		0.52 (0.50)		0.26 (0.44)		0.24 (0.43)		0.72 (0.45)
	Tertiary	1.94 (1.16)		0.57 (0.50)		0.30 (0.46)		0.28 (0.45)		0.80 (0.40)
Employment Status	Employed	2.00 (1.13)	0.00*	0.61 (0.49)	0.00*	0.33 (0.47)	0.01*	0.28 (0.45)	0.25	0.79 (0.41)	0.00*
	Studying	1.53 (0.88)		0.33 (0.47)		0.16 (0.37)		0.16 (0.37)		0.88 (0.32)
	Unemployed or retired	1.47 (1.23)		0.48 (0.50)		0.17 (0.38)		0.25 (0.44)		0.56 (0.50)
User of the public health system	Yes	1.75 (1.18)	0.00*	0.53 (0.50)	0.27	0.26 (0.44)	0.31	0.26 (0.44)	0.96	0.69 (0.46)	0.01*
	No	2.01 (1.09)		0.59 (0.49)		0.31 (0.46)		0.27 (0.44)		0.85 (0.36)
Net Income per month	<R10 000	1.73 (1.13)	0.10	0.53 (0.50)	0.69	0.23 (0.42)	0.06	0.25 (0.44)	0.42	0.72 (0.45)	0.19
	R10 001 to 20,000	1.92 (1.11)		0.58 (0.50)		0.30 (0.46)		0.24 (0.43)		0.80 (0.40)
	Over 20,000	2.03 (1.19)		0.57 (0.50)		0.36 (0.48)		0.31 (0.47)		0.79 (0.41)
Are You a Health-care worker	Yes	2.68 (1.03)	0.00*	0.86 (0.35)	0.00*	0.57 (0.50)	0.00*	0.30 (0.46)	0.63	0.95 (0.23)	0.01*
	No	1.78 (1.12)		0.52 (0.50)		0.25 (0.44)		0.26 (0.44)		0.75 (0.44)
Is there a Health-care worker in Your family	Yes	1.98 (1.07)	0.11	0.58 (0.50)	0.55	0.30 (0.46)	0.63	0.25 (0.43)	0.60	0.85 (0.35)	0.00*
	No	1.81 (1.18)		0.54 (0.50)		0.28 (0.45)		0.27 (0.45)		0.72 (0.45)
Total average score		1.87		0.56		0.28		0.26		0.76

Notes: *p ≤ 0.05 derived using Mann–Whitney U-test or Kruskal–Wallis test where applicable. Bold and Highlighted cells represent significant values.

Abbreviation: SD: standard deviation.

Concerning the total knowledge score, four sociodemographic factors were found to score significantly greater (p ≤ 0.05) than their counterparts in terms of participants’ total mean knowledge. Females were found to be more knowledgeable ( = 1.97, SD = 1.12). Those who were employed ( = 2.00, SD = 1.13) and those who did not make use of the public health care system were more knowledgeable ( = 2.01, SD = 1.09). Health-care workers achieved a greater overall mean knowledge score ( = 2.68, SD = 1.03).

More than half of the participants (55.6%) reported being aware of medicine waste. Sociodemographic factors significantly affecting (p ≤ 0.05) awareness of medicine waste include participants in the age 51 and older group, who scored significantly more ( = 0.65, SD=0.48) than younger participants. Health-care workers scored higher ( = 0.86, SD = 0.35) than non-health-care workers. Employed participants scored higher ( = 0.61, SD = 0.49) than students and the unemployed.

Just over a quarter (28.4%) of participants reported having been informed about the safe and proper disposal of expired and unused medicines. Upon analysis, two sociodemographic factors were significantly different from their counterparts (p ≤ 0.05). Those who were employed scored higher ( = 0.33, SD = 0.47) than the unemployed, students or retired individuals. Health-care workers scored higher ( = 0.57, SD = 0.50) than non-health-care workers.

When assessing the total knowledge score for significant sociodemographic predictors (p ≤ 0.05), summarized in Table 3, the following factors were found to be significant: being female (β = 0.25, R² = 0.01), employed (β = 0.48, R² = 0.04), being a user of the private healthcare system (β = 0.16, R² = 0.04) and being a health-care worker (β = −0.89, R² = 0.02), in this last result a smaller value indicated a greater correlation between been a health-care worker and total attitude score.

Table 3.

Bloemfontein Residents’ Sociodemographic Predictors of Total Knowledge, Attitudes and Practice Scores (n=394) (June 2024)

Sociodemographic Variable		Total Knowledge					Total Attitudes						Total Practices
		β	CI		p-value	R2	β		CI		p-value	R2	β		CI		p-value	R2
			Lower	Upper					Lower	Upper					Lower	Upper
Gender	Male	0.25	0.00	0.09	0.03*	0.01	0.15		−0.01	0.02	0.66	0.00	0.15		−0.03	0.13	0.01*	0.02
	Female
Age	18-30	0.01	−0.06	0.06	0.95	0.00	0.64		−0.01	0.02	0.80	0.00	0.05		0.04	0.25	0.25	0.00
	31-50
	51 and over
Higher Levels of Education	No formal High School Education	0.14	0.00	0.09	0.22	0.00	0.01		0.00	0.03	0.10	0.01	0.09		0.00	0.18	0.04*	0.01
	High School
	Tertiary
Employment Status	Employed	0.48	−0.08	−0.02	0.00*	0.02	−0.01		−0.02	0.01	0.26	0.00	−0.11		−0.1	0.02	0.21	0.00
	Studying
	Unemployed or retired
User of the public health system	Yes	0.27	0.01	0.09	0.02*	0.01	0.01		−0.01	0.02	0.40	0.00	0.12		0	0.15	0.06	0.01
	No
Net Income per month	<R10 000	−0.05	0.01	0.15	0.54	0.01	0.01		−0.02	0.03	0.34	0.00	0.02		0.05	0.31	0.65	0.00
	R10 001 to 20,000
	Over 20,000
Are You a Health-care worker	Yes	−0.89	−0.08	−0.03	0.00*	0.05	−0.01		−0.02	0.00	0.04*	0.01	−0.47		−0.15	−0.06	0.00*	0.05
	No
Is there a Health-care worker in Your family	Yes	0.17	−0.07	0.01	0.16	0.01	0.00		−0.01	0.02	0.74	0.02	−0.06		−0.14	0.02	0.12	0.01
	No

Notes: β = Unstandardized value; *p ≤ 0.05; R²: Regression co-efficient; Bold and highlighted cells represent significant values.

Abbreviation: CI, Confidence interval.

When respondents were asked if they had ever read medicine disposal instructions, 26.4% of respondents reported having read medicine disposal instructions, whereas 73.4% of respondents reported having never read medicine disposal instructions. No sociodemographic factors were found to be significant in this regard.

In this study, 76% of participants were found to agree that improper disposal of unused and expired medicines may impact the environment and public health.

Total Attitude and Individual Question Scores per Socio-Demographic Factor

Results from the attitudes section are reported in Table 4. The collective mean for the attitudes section was 16.50 out of 20. Three sociodemographic variables were found to score a significantly greater total attitude score (p ≤ 0.05). Health-care workers ( = 17.54, SD = 2.80) scored a higher mean score than non-health-care workers. Students ( = 16.65, SD = 2.79) scored more than the employed, retired or unemployed. Those with tertiary education also scored higher ( = 16.63, SD = 3.22) than those with lower levels of education.

Table 4.

Bloemfontein Residents’ Attitudes Scores of Unused and Expired Medicine Disposal by Socio-Demographic Variable (June 2024) (n=394)

Sociodemographic variable		Total Attitudes		Vulnerability of Children to Medicine Waste		Lack of Information Availability to Medicine Waste			Information Provision of Medicine Waste by HCPs			Inclusion of Medicine Take-Back Programs
		Mean (SD)	p-value	Mean (SD)	p-value	Mean (SD)	p-value		Mean (SD)		p-value	Mean (SD)		p-value
Gender	Male	16.40 (0.90)	0.08	3.96 (1.01)	0.08	3.93 (0.94)	0.57		4.24 (0.86)		0.14	4.28 (0.90)		0.29
	Female	16.55 (1.05)		4.07 (1.11)		3.92 (1.10)			4.28 (1.02)			4.30 (1.05)
Age	18-30	16.47 (3.20)	0.95	4.02 (1.13)	0.94	3.85 (1.05)	0.64		4.30 (1.01)		0.28	4.29 (0.94)		0.87
	31-50	16.48 (3.38)		4.03 (1.05)		3.94 (1.06)			4.26 0 (0.99)			4.26 (1.05)
	51 and over	16.61 (2.66)		4.02 (1.05)		4.00 (0.94)			4.23 (0.78)			4.37 (0.89)
Highest Level of Education	No formal High School Education	14.45 (3.39)	0.00*	3.82 (0.87)	0.16	3.18 (1.17)	0.05*		3.55 (1.13)		0.00*	3.91 (1.14)		0.03*
	High School	16.40 (2.72)		4.00 (0.85)		3.97 (0.85)			4.20 (0.189)			4.24 (0.88)
	Tertiary	16.63 (3.22)		4.05 (1.12)		3.93 (1.11)			4.32 (0.98)			4.33 (1.04)
Employment Status	Employed	16.56 (3.39)	0.05*	4.16 (1.04)	0.06	3.95 (1.08)	0.20		4.30 (0.98)		0.06	4.28 (1.04)		0.81
	Studying	16.65 (2.79)		4.05 (1.09)		3.93 (0.94)			4.26 (1.03)			4.30 (0.89)
	Unemployed or retired	16.08 (2.64)		3,84 (0.98)		3.80 (0.93)			4.13 (0.85)			4.31 (0.81)
User of the public health system	Yes	16.37 (3.09)	0.13	4.02 (1.02)	0.44	3.86 (0.97)	0.01*		4.20 (0.97)		0.03*	4.31 (089)		0.51
	No	16.64 (3.36)		4.03 (1.13)		1.11 (0.97)			4.35 (0.95)			4.26 (1.11)
Net Income per month	<R10 000	16.38 (3.28)	0.61	3.99 (1.07)	0.64	3.90 (1.00)	0.64		4.24 (0.96)		0.80	4.26 (1.04)		0.72
	R10 001 to 20,000	16.78 (2.97)		4.11 (0.99)		3.99 (0.97)			4.30 (0.90)			4.38 (0.87)
	Over 20,000	16.38 (3.22)		3.99 (1.16)		3.89 (1.17)			4.26 (1.03)			4.24 (1.05)
Are You a Health-care worker	Yes	17.54 (2.80)	0.01*	4.27 (0.90)	0.16	4.19 (0.97)	0.06		4.57 (0.83)		0.01*	4.51 (0.99)		0.03*
	No	16.39 (3.24)		4.00 (1.09)		3.89 (1.04)			4.23 (0.97)			4.26 (0.99)
Is there a Health-care worker in Your family	Yes	16.42 (3.59)	0.67	4.04 (1.15)	0.44	3.90 (1.14)	0.75		4.23 (1.01)		0.77	4.26 (1.04)		0.94
	No	16.54 (3.00)		4.02 (1.03)		3.93 (0.98)			4.28 (0.93)			4.30 (0.97)
Total average score		16.50		4.03		3.92			4.26			4.29

Notes: *p ≤ 0.05 derived using Mann–Whitney U-test or Kruskal–Wallis test where applicable. Bold and highlighted cells represent significant values.

Abbreviation: CI, Confidence interval.

As seen in Table 4, two sociodemographic factors presented a significant difference (p ≤ 0.05) with regard to participants’ attitudes towards the lack of medicine disposal. More educated participants ( = 2.68, SD = 1.03) and those who used the public health care system ( = 2.68, SD = 1.03) scored higher and were thus more likely to agree with this statement.

Participants reported an average score of 4.26 when asked about their attitudes towards nurses, doctors, and pharmacists being responsible for providing advice on the safe disposal of unused and expired household medicine. A host of sociodemographic factors were found to score significantly greater (p ≤ 0.05). Health-care workers ( = 4.57, SD = 0.83), users of the public healthcare system ( = 4.20, SD = 0.97), and lastly, those with a tertiary level of education ( = 4.35, SD = 0.95) achieved greater Likert scores, as seen in Table 3.

The last question within the attitudes section pertained to whether participants would agree or not to “take back” programs that allow for the collection of unused or expired medicine from residents within their communities. The collective score for this was 4.29. This resulted in the highest level of agreement in the survey. Two sociodemographic factors were found to vary significantly (p ≤ 0.05). Those with a tertiary level of education scored the highest ( = 4.33, SD = 1.04), trumping those with less education. Health-care workers scored higher ( = 4.57, SD = 0.83), feeling more strongly in favor of take-back programs, as seen in Table 4.

As seen in Table 3, only one sociodemographic predictor is associated with attitudes regarding the appropriate disposal of medicines. Health-care workers were associated with higher total attitude scores (β = −0.01, R² = 0.01); in this result, a smaller value indicated a greater correlation between being a health-care worker and total attitude score.

Total Practice and Individual Question Scores per Socio-Demographic Factor

The mean score of the practices section was 0.34 out of 4. This score reflects that the residents of Bloemfontein have poor practices regarding the disposal of unused and expired medicines. Results from the Practice section are summarized in Table 5.

Table 5.

Bloemfontein Residents’ Practice Scores of Unused and Expired Medicine Disposal by Socio-Demographic Variable (June 2024) (n=394)

Sociodemographic Variable		Total Practices		Possession of Unused Medicine at Home		Actions Taken Regarding Expired Medicine		Actions Taken Regarding Unused Medicine		Method of Disposal of Unused Medicines
		Mean (SD)	p-value	Mean (SD)	p-value	Mean (SD)	p-value	Mean (SD)	p-value	Mean (SD)	p-value
Gender	Male	0.20 (0.52)	0.53	0.10 (0.30)	0.85	0.03 (0.16)	0.13	0.02 (0.14)	0.05*	0.16 (0.36)	0.96
	Female	0.28 (0.68)		0.09 (0.29)		0.06 (0.24)		0.06 (0.24)		0.15 (0.36)
Age	18–30	0.16 (0.41)	0.16	0.04 (0.20)	0.09	0.03 (0.16)	0.01*	0.01 (0.09)	0.18	0.12 (0.33)	0.02*
	31–50	0.24 (0.61)		0.12 (0.33)		0.04 (0.20)		0.05 (0.21)		0.15 (0.23)
	51 and over	0.44 (0.92)		0.10 (0.3)		0.10 (0.30)		0.11 (0.32)		0.23 (0.42)
Highest Level of Education	No formal High School Education	0.00 (0.00)	0.26	0.00 (0.00)	0.43	0.00 (0.00)	0.11	0.00 (0.00)	0.03*	0.00 (0.00)	0.35
	High School	0.18 (0.41)		0.08 (0.27)		0.02 (0.13)		0.01 (0.09)		0.15 (0.36)
	Tertiary	0.29 (0.71)		0.10 (0.31)		0.06 (0.24)		0.07 (0.25)		0.16 (0.35)
Employment Status	Employed	0.28 (0.69)	0.68	0.10 (0.31)	0.49	0.06 (0.23)	0.29	0.05 (0.22)	0.58	0.17 (0.37)	0.49
	Studying	0.19 (0.39)		0.07 (0.26)		0.02 (0.15)		0.02 (0.15)		0.14 (0.35)
	Unemployed or retired	0.16 (0.41)		0.06 (0.244)		0.02 (0.13)		0.03 (0.18)		0.11 (0.32)
User of the public health system	Yes	0.19 (0.51)	0.20	0.07 (0.26)	0.08	0.03 (0.18)	0.19	0.02 (0.15)	0.02*	0.14 (0.34)	0.27
	No	0.31 (0.73)		0.12 (0.33)		0.06 (0.24)		0.07 (0.26)		0.18 (3.83)
Net Income per month	<R10 000	0.13 (0.41)	0.01*	0.07 (0.26)	0.25	0.03 (0.17)	0.30	0.01 (0.11)	0.01*	0.09 (0.11)	0.01*
	R10 001 to 20 000	0.35 (0.80)		0.13 (0.34)		0.07 (0.25)		0.09 (0.28)		0.20 (0.40)
	Over 20 000	0.32 (0.66)		0.09 (0.29)		0.05 (0.21)		0.06 (0.23)		0.22 (0.41)
Are You a Health-care worker	Yes	0.68 (1.03)	0.01*	0.22 (0.42)	0.01*	0.14 (0.35)	0.00*	0.19 (0.40)	0.00*	0.35 (0.48)	0.00*
	No	0.20 (0.55)		0.08 (0.27)		0.04 (0.19)		0.03 (0.17)		0.13 (0.34)
Is there a Health-care worker in Your family	Yes	0.13 (0.70)	0.09	0.12 (0.33)	0.13	0.05 (0.22)	0.71	0.07 (0.25)	0.17	0.20 (0.40)	0.09
	No	0.31 (0.58)		0.08 (0.27)		0.04 (0.20)		0.04 (0.18)		0.13 (0.34)
Section total		0.34		0.09		0.05		0.05		0.15

Notes: *p ≤ 0.05 derived using Mann–Whitney U-test or Kruskal–Wallis test where applicable. Bold and highlighted cells represent significant values.

Two factors were found to be significantly (p ≤ 0.05) higher for the total practice score: a greater monthly net income, R10001 to R20000 ( = 0.35, SD = 0.80) and being a health-care worker ( = 0.68, SD = 1.03).

The first question posed to participants concerned the possession of unused medicine amongst residents in Bloemfontein. 357 participants (90.6%) reported keeping unused medicine at their place of residence. Summarized in Table 5, just 37 (9.4%) of participants reported not keeping unused medicine at their place of residence. Health-care workers scored significantly (p ≤ 0.05) higher ( = 0.22, SD = 0.42) in this question.

The second question concerned the methods Bloemfontein residents used to dispose of expired medicine. As seen in Table 5, 80.2% of participants opted to dispose of expired medicine. Another option chosen by 1.3% of participants was to give away unused medicine. Alternatively, 14% of participants simply kept their unused medicine. Lastly, only 4.6% of participants returned their unused medicine to pharmacies. One sociodemographic factor presented a significant difference (p ≤ 0.05). Those aged 51 and over scored higher ( = 0.10, SD = 0.30) than those aged 50 and younger who opted for appropriate disposal methods.

In contrast to expired medicine, respondents’ choices regarding unused medicine included the following: 57.6% chose to dispose of it. 8.1% of participants chose to donate their unused medicine, and 29.7% chose to keep it. 4.6% of patients returned their expired medicine to pharmacies. The sociodemographic factors in Table 5 achieved significantly greater results than their counterparts (p ≤ 0.05). With regards to the above question, females scored significantly higher ( = 0.06, SD = 0.24). Those with at least a high school education achieved higher scores ( = 0.07, SD = 0.25). Those who did not use the public health system obtained a higher score ( = 0.07, SD = 0.26). Participants with a take-home salary between R10001and R20000also achieved a higher average score ( = 0.09, SD = 0.28). Lastly, health-care workers achieved a significantly higher score ( = 0.19, SD = 0.40).

Regarding the disposal practices for unused medicine, as shown in Table 5, a collective score of zero (0) was achieved. Older participants (aged 51 and older) scored higher ( = 0.23, SD = 0.42) than younger participants. Participants with a higher monthly net income (over R20,000) achieved a higher average score ( = 0. 0.22, SD = 0.41). Health-care workers achieved a higher score ( = 0.35, SD = 0.48) compared to non-health-care workers.

Sociodemographic factors, which were significant predictors (p ≤ 0.05) of a greater overall mean practice, are included in Table 3. This included gender, where being a female achieved a greater score (β = 0.15, R² = 0.02), having a higher level of education achieved a greater score (β = 0.09, R² = 0.01) and being a health-care worker (β = −0.47, R² = 0.05)), in this last result a smaller value indicated a greater correlation between been a health-care worker and total attitude score.

Correlation of Knowledge, Attitudes and Practices Regarding Disposal of Unused and Expired Medicines

As per Table 6, there was a significant (p ≤ 0.05) weak positive correlation (r = 0.14, n = 394) where the greater the mean knowledge a resident of Bloemfontein possessed toward the disposal of unused and expired medicine, the more positive their attitudes were regarding the disposal of unused and expired medicines.

Table 6.

Interrelated Correlations Between Knowledge, Attitudes and Practices of Bloemfontein Residents (June 2024) (n=394)

		Knowledge Section	Attitudes Section	Practices Section
Knowledge section	Correlation Coefficient	1	0.14	0.02
	p-value		0.01*	0.64
	n	394	394	394
Attitudes section	Correlation Coefficient	0.14	1.00	0.02
	p-value	0.01*		0.714
	n	394	394	394
Practices section	Correlation Coefficient	0.02	0.02	1.00
	p-value	0.64	0.71
	n	394	394	394

Note: *p ≤ 0.05; Spearman Correlation test. Bold and highlighted cells represent significant values.

Discussion

This study aims to assess residents’ knowledge, attitudes, and practices regarding the disposal of unused and expired medicines in Bloemfontein, Free State. The results of this study indicate poor knowledge, much like other South African studies,9,15,16 positive attitudes and inappropriate medication disposal practices amongst Bloemfontein residents.

This study shows that health-care workers were associated with a significantly higher total score and achieved a higher total score across the domains of knowledge (possibly influenced by their training), attitudes, and practices. These findings align with results from a previous study in South Africa which found similar knowledge and practice scores amongst health-care workers. Despite achieving higher levels of knowledge and positive attitudes with regard to medicine disposal, the majority of health-care workers in South Africa and other developing nations incorrectly dispose of medicines.36–38 These findings are worrying, as the individuals responsible for educating and advising are not adequately trained themselves.

Females demonstrated a significantly better knowledge and were more associated with a higher knowledge score in this demographic. While no other South African studies identified a relationship between females and medical waste knowledge, similar studies in Africa and developing nations did. A study conducted in the United Arab Emirates found that 77% of females demonstrated a sufficient level of knowledge as opposed to only 23% of males.38 These findings support another study conducted in Lebanon in 2022, which found that females were more knowledgeable in the field of medical waste disposal.35 Internationally, there is no evidence to support a difference in medicine disposal knowledge by gender.39,40 These results may be justified as females are more likely to visit pharmacies due to traditionally being the primary caretaker and may be more exposed to medicine disposal information during the dispensing process.41

The employed were found to possess significantly greater appropriate medicine disposal knowledge, and being a predictor of more appropriate medicine disposal knowledge was also found. Compared to data available on the African continent, a study by Dweik et al (2024) found that the employed ( = 0.40, p < 0.00) or student participants ( = 0.41, p < 0.00) were significantly more informed and knowledgeable of medicine waste.38 These populations may be more likely to be exposed to workplace or institutional healthcare resources and consequently have higher levels of health literacy.42

Individuals with access to privately funded healthcare tend to have more resources, including healthcare education.43 This can clearly be seen in those who did not use the public healthcare system, who were found to be more knowledgeable about appropriate medicine disposal and more aware of the impact that improper disposal of medicine may have on environmental and public health.

Attitudes towards the appropriate disposal of medicine amongst Bloemfontein residents were positive, as was found in a similar study performed in Bangladesh.37 In this questionnaire-based study, sociodemographic factors were found to have a significant difference in participants’ total mean attitude scores.

Those with higher levels of education may support proposed models suggesting that educational attainment may lead to improved health education and its associated potential environmental impact.44,45 These individuals may also understand and appreciate that the correct knowledge should be conveyed by qualified individuals. Similar findings were documented when examining an educator’s roles when teaching students with disabilities.46

Encouragingly, health-care workers acknowledged their role in the appropriate disposal of medication. Supporting this, South African Healthcare workers were found to have a strong sense of social and professional responsibility toward medication waste in a study which explored reducing medicine waste through individualized prescribing.47 This is further evidence that healthcare workers feel more invested in or responsible for the concept than those not in the healthcare industry. This was seen in participants scoring higher on total attitude, with a strong association with higher total attitude scores.

It has been documented that employment status may positively affect environmental attitudes. Preservation of the environment may be driven by greater financial security and exposure to workplace environmental considerations and sustainability concepts.48 With increasing focus on environmental conservation, these factors may permeate into related environmental issues such as appropriate medicine disposal.

An intriguing finding was that users of the public healthcare system were found. This segment of the demographic not only agreed at a significant level that there is not enough information available on medicine disposal, but also achieved a lower total knowledge score at a significant level and obtained the lowest practices score. In addition to these findings, this demographic maintains a positive attitude toward medical waste disposal. Implementation of medicine disposal programs or drives may yield positive results amongst this specific demographic as has been recommended in similar South African literature.49

The practice of appropriate medical waste disposal is concerning, as evidenced not only by this study but also by other studies conducted in South Africa.9,15,16,25 It is worth noting that total disposal practices were found to be poor across all sociodemographic factors. Similar results were presented in all other reviewed South African studies. In Johannesburg, only 13.2% of participants returned medicine to pharmacies.15 In Durban, 13% of participants (who kept unused and expired medicines) returned them to pharmacies or hospitals.25 In Cape Town, 21% of participants (who kept unused and expired medicines) returned them to pharmacies.16 In Pretoria, a mere seven percent of participants returned their unused and expired medicines to pharmacies.9

This study found that 15.5% of participants returned their unused or expired medicines to pharmacies. These results demonstrate the dire situation of inappropriate medicine disposal across South Africa.

Insight into more appropriate disposal by females than by males is supported by international studies. These studies dispute the idea that females are more environmentally friendly than males.50,51 In this study, older participants (51 and older) scored higher than younger participants when considering the appropriate disposal of expired medicines and their actions taken towards disposing of unused medicines. Such behaviour may be attributed to older individuals’ sense of environmental responsibility for future generations.52 These results may further contribute to the debate concerning African environmental ethics, which has been described as misunderstood and at worst unsustainable.53,54

Much like this study, research performed in Indonesia, a developing country much like South Africa, found that participants with more education practiced better household waste management compared to their younger and less educated counterparts.55 A study by Brown (2014) among first world countries found that increased initiatives in waste management increased participation among more educated participants.56 This information demonstrates that increasing awareness of medicine waste disposal among more educated individuals may collectively improve medicine waste practices.

Interestingly, those with a higher net monthly income achieved a significantly higher total practice score; these included groups earning between R10 001 and R20,000, as well as those earning R20 001 or more.

The above may be explained by the fact that those who earned more money had a higher likelihood of exposure to private healthcare (while not significant, these users did score higher than Public Healthcare users), which, in South Africa, is known to be concerned with effective waste management programs and other environmentally sustainable practices.57 This is in stark contrast to a recent report by the Free State Department of Health, which places the public health care facilities of the district in which Bloemfontein is situated, among the worst performers in terms of management of health care waste in the province.58

A weak positive relationship between a higher knowledge section score and a higher attitudes score was identified; this exemplifies the issue that if citizens are aware and informed of the issue at hand, they are more likely to possess a positive attitude. No such correlation between practices was discovered. However, poor practices amongst South Africans may suggest that there are insufficient opportunities for residents to appropriately dispose of their unused and expired medicines.9,15,16,25 This further supports the need to raise awareness within pharmacies, which, by law, must follow appropriate medicine disposal protocols.59

This study reveals significant gaps in knowledge, attitudes, and practices regarding household medicine disposal in Bloemfontein, with important implications for public health practice, policy, and environmental protection. Considering the three results in relationship to one another, there is a definite disconnect or deficit between the three domains.

These results further highlight the environmental implications introduced in the introduction to this study.5

Limitations

With a response rate of 97.2%, a response bias may have been present due to the nature of some survey questions. Potential participants chose not to participate in the survey after reviewing the survey’s questions. Some participants opted out of the survey after reaching a question such as take-home salary. Other participants chose to opt out of the survey after finding it uninteresting or deciding it would be too time-consuming. This may contribute to the unintended generalizability of the study. Many potential participants simply refused to participate in the survey. This reduced the number of potential participants.

To reduce response bias, the number of questions asked was kept minimal. Special care was taken for the avoidance of sensitive questions. A friendly and approachable attitude was always adopted when asking potential participants to take part in the survey. In addition to these measures, participants were always assured of confidentiality regarding more sensitive questions.

Failed omissions naturally took place. The researcher inspected each survey for failed omissions upon receipt. When a failed omission was detected, best efforts were made to trace the respondent for potential rectification. At times, contact could not be made, and these surveys were omitted.

Although attempts were made to reach all major areas of the city, permission to access some of them was not granted. This may mean the study is not completely representative of all geographical areas of the city and may thus be at risk of further generalizability. Physically approaching management would prove more successful if the previous electronic mail was not responded to. Adding to the issue of generalizability, usage of convenience sampling may have further contributed to the limitation of generalizability.

The issue of social desirability may have been present, potentially inflating results. The issue was addressed by assuring the participant that responses to the survey would be completely anonymous.

While the study encountered numerous difficulties in obtaining permission to conduct research, breakthroughs were made, creating opportunities for data collection. The calculated required sample size was not only met but surpassed. This allowed the study to address its aim and research questions effectively.

Conclusion

This study assessed knowledge, attitudes and practices regarding the disposal of unused and expired medicines among adult residents of Bloemfontein, revealing poor knowledge and particularly poor disposal practices, despite generally positive attitudes towards environmentally responsible medicine disposal and the role of health-care providers in advising on safe practices. Sociodemographic determinants were evident: being female, employed, more educated, a health-care worker, and having higher income or access to private health care were associated with higher knowledge and more appropriate attitudes and practices, although even health-care workers frequently reported incorrect disposal behaviors. The weak but significant positive correlation between knowledge and attitudes, coupled with the absence of a similar relationship with practices, highlights a persistent disconnect between what residents know or believe and what they do in practice. In line with previous South African studies, the low proportion of participants returning medicines to pharmacies underscores the lack of convenient, trusted, and well-communicated disposal pathways at community level. These patterns suggest that structural and system-level barriers, rather than attitudes alone, play a central role in sustaining inappropriate disposal.

Targeted, multi‑level interventions are therefore warranted. Integrating routine counselling on medicine disposal into pharmacy and other health-care encounters, expanding accessible take‑back options at pharmacies under an extended producer responsibility framework, and implementing sustained community awareness campaigns could collectively strengthen safe disposal behaviors. Particular attention should be directed to public-sector users and lower‑income groups, who demonstrated lower knowledge and poorer practices yet expressed willingness and positive attitudes, indicating receptivity to well-designed interventions. Future research should explore household medicine disposal in rural and under‑resourced settings and evaluate the impact, feasibility and cost‑effectiveness of implemented disposal initiatives over time.

Recommendations

The following recommendations may mitigate potential consequences. Health-care providers should integrate targeted counselling and dispensing medication to educate patients on safe disposal, particularly in public facilities where awareness is lowest. Implementing medicine take-back programs at pharmacies supported by extended producer responsibility would provide accessible return points, reducing environmental contamination and accidental misuse.48,60,61 Public awareness campaigns through social media and community materials, alongside posters and pamphlets in clinics, can reinforce pharmacies as disposal hubs and highlight health risks.62–64 These multifaceted strategies align with South Africa’s regulatory framework to improve compliance and outcomes.

Further research may focus on conducting similar studies in more rural areas where reliance on public healthcare is greater, as all studies to date have been performed in urban areas. Research into the application of suggestions and the reactions to these applications may also be of value.

Disclosure

The author(s) report no conflicts of interest in this work.