The study was carried out in the informal settlements of Nairobi County, Kenya. Nairobi serves as the capital city of Kenya and has 17 sub-counties with a population of over four million people according to the 2019 census report ( Kenya National Bureau of Statistics, 2019). The majority of these people are low-income earners who live in informal settlements distributed across these sub-counties. Two sub-counties were purposively selected for this study, which include Kibra and Dagoretti North. The areas were purposively chosen since they contain some of the largest informal settlements in the county with a high population density.

Figure 1 shows the locations of Kibra and Dagoretti North. Kibra is located to the southwest of the city of Nairobi, it is approximately 12.1km² and has a population of around 178,000 people. Dagoretti North is located to the west of Nairobi city, it is approximately 29 km² with a population of around 181,000 people. These two regions have areas characterized by unplanned settlements, poor quality of housing, inadequate access to safe water and sanitation, and poor drainage systems among others.

A cross-sectional design was used to carry out the study. This design was appropriate for the study since it made it possible to estimate the extent of the outcome of interest which, in this case, is the level of hygienic knowledge and practices of vendors and also enabled the assessment of many study outcomes within a reasonable time ( Kesmodel, 2018).

The informal settlements of Kibra and Dagoretti North represent the setting where the study was conducted. In Kibra, four wards were purposively selected for the study, these include Makina, Laini Saba, Lindi, and Sarang’ombe. In Dagoretti North, two wards were purposively selected, which include Kawangware and Gatina wards. These areas are characterized majorly by informal settlements and structures along which milk vending machines are stationed. The vending machines are randomly distributed in the areas without any specific order.

The study population comprised of all milk handlers operating milk vending machines located in the informal areas of Kibra and Dagoretti North. A pre-visit was conducted at the study setting to establish the total number of milk vending machine handlers available and in operation. A representative from the Kenya Dairy Board, a regulatory body in the dairy industry, also formed part of the study population, the representative officer was invited to participate in the study through a formal request to the regulatory institution.

An exhaustive sampling of the available milk vending machine handlers was carried out in the study areas, a total of 37 milk vendors operating milk vending machines were identified, 20 of them were from Dagoretti North while 17 from Kibra. All the vendors identified were included in the study.

The sampling of milk vending machine handlers for interviews was conducted within a period of one month, in October 2020; this began with Dagoretti North then followed by Kibra. Respondents were physically invited for the interviews through one-on-one engagement by explaining the nature and purpose of the interview. The interviews were conducted daily at the respondents’ milk vending machine premises with informed consent obtained from the vendors before an interview by explaining to them the objectives of the study and assuring them of the confidentiality of their data. All the available milk vending machine handlers within the study setting were interviewed individually using semi-structured questionnaires with every interview taking roughly 20 minutes to 30 minutes.

Interviews were conducted by the corresponding author at the study site after undertaking relevant training on conducting research interviews. A questionnaire containing 26 questions was first pilot tested on a sample of the respondents and modified according to the observations from the pilot test before the actual interview. Vendors were interviewed on a face-to-face basis to validate the accuracy of the responses, with the interviews being conducted either in English or Swahili (through translation) using semi-structured questionnaires. The questionnaire was divided into three sections with the first part of it capturing the socio-demographic characteristics of the respondents with details about their gender, age, and level of education. The second part entailed 15 questions with the choices of True, False, and Don’t Know to assess the hygiene knowledge of the respondents. The third part of the questionnaire had 21 questions covering the practices of handlers with choices of Yes, No, or a structured answer which the interviewer interpreted to be either the right or wrong practice. A copy of the questionnaire can be found in the Extended data. A representative from the Kenya Dairy Board was also interviewed separately at the institution’s premises following official appointment request to conduct the interview by the corresponding author. The officer was interviewed on a one-on-one basis on measures the institution is putting in place to ensure that regulations governing the operation of milk vending machines are adhered to. A copy of the questionnaire can be found in the Underlying data (in the “Holi Regulator's Questionnaire.docx” which also contains the answers). No follow-ups were conducted after the interviews.

Research tools used to collect the data include questionnaires for conducting interviews, pencils, and erasers for recording feedback from respondents on copies of the questionnaires by the corresponding author, datasheets, a camera for taking photos of the study area and the nature of its surroundings, and a stationery bag to store the data collection materials. Results from the interviews were then recorded on a datasheet for analysis. This data was stored in sealed envelopes under lock and key for security purposes and labeled “confidential,” only to be opened during analysis.

Data was analyzed using Statistical Package for Social Sciences software (IBM SPSS v25). Each study question was classified and assigned points, responses on questions assessing the hygiene knowledge of respondents were categorized as either correct or incorrect. For every correct answer, one point was awarded while an incorrect response was awarded zero points. On questions assessing the hygiene practice of respondents, one point was awarded for the right practice while a bad practice was awarded zero points. All the scores for handling knowledge and practices of respondents were tallied and calculated as a percentage. Individual scores for questions on knowledge and practices were summarized using frequencies and descriptive statistics. Pearson’s correlation coefficient was used to establish an association between knowledge and practices of respondents. Scores above 75% were considered to be indicative of high knowledge and good practice with statistical significance set at p<0.05. Responses from the Kenya Dairy Board’s representative were assessed based on the milk vending machine quality manual from the institution and presented descriptively by stating the regulatory measures being put in place and the existing gaps.

Potential sources of bias were addressed by involving the participating authors to independently interpret the data for comparison and verifying the findings with other similar data sources supporting the findings. The findings and conclusions were also shared with peers for review.

Out of 37 milk vendors who were enrolled in the study as respondents, 56.8% were male and 43.2% were female. Out of the total male respondents, 61.9% were from Dagoretti North while 38.1% from Kibra. Out of the total female respondents, 43.8% were from Dagoretti North while 56.2% of them from Kibra. From these respondents, the youngest was 20 years and the oldest 45 was years with their mean age being 26 years. There was no significant difference ( p=0.51) between the ages of males and that of females. In Kibra, the mean age of the respondents was 26.18 while in Dagoretti North it was 26.05, the difference in the average age of the two study areas was, however, not significant ( p=0.95).

The majority of the respondents (64.9%) had attained secondary education with only 21.6% having tertiary education and 13.5% primary education. In Dagoretti North, 5% of the respondents had primary education, 70% secondary education, and 25% with tertiary education. In Kibra, those with primary education were 23.6%, 58.8% having secondary education, and 17.6% tertiary education ( Table 1).

Out of the total percentage of males (56.8%), 28.6% had attained tertiary education, and 66.6% had secondary education, while only 4.8% had primary education. Among the females (43.2%), 12.5% had attained tertiary education, 62.5% had secondary education, and 25% had primary education ( Table 2). Differences in the level of education between males and females as calculated using Fisher’s exact test was however not significant ( p=0.2).

Table 3 shows hygiene knowledge responses by milk vending machine handlers for this study. Milk vending machine handlers had a low level of knowledge on milk hygiene with a mean percentage score of 68.83±11.2. Male respondents registered a higher knowledge score of 68.88±11.02 compared to females with 68.74±11.86, but the difference was not statistically significant ( p=0.97). The mean percentage score of vendors’ knowledge in Dagoretti North was 72.66±11.2 while in Kibra it was 64.31±9.7 with the difference being significant ( p=0.02). Milk hygiene knowledge scores increased with the level of education; vendors with college education showed a high hygiene knowledge on milk handling (76.67±11.8), followed by those with secondary education (67.78±10.5), and lastly those with primary education (61.33±7.3), with the difference in their knowledge scores being significant ( p=0.04 and F=3.632).

The majority of the respondents (89.25%) correctly answered that only pasteurized milk should be stored and sold from the vending machines with all the respondents (100%) not knowing that pasteurized milk, despite being safe for consumption, can be contaminated by microorganisms. More than half (75.7%) of the respondents thought that any detergent and disinfectant can be used to clean milk vending machines with 100% of them believing that water used for cleaning milk vending machines should be one that is also safe for drinking. Additionally, only 43.2% of the respondents believed that milk vendors should undergo medical checkups to ensure they are free from contagious diseases. About 75.7% of the vendors believed that milk should only be purchased from licensed suppliers. The majority of the respondents (81.1%) believed that milk storage containers should not be used to store other liquid materials. About 35.1% of vendors believed that milk can be stored in the vending machines at any temperature while 56.8% of them stated that milk can be kept in the vending machines for more than 24 hours. More than half of the respondents (64.9%) did not know that there are laws and regulations that guide the selling of milk using milk vending machines.

Table 4 shows vendor practices responses by milk vending machine handlers for this study. Milk vending machine handlers in the current study demonstrated poor milk handling practices with a mean percentage score of 54.05±11.5. Male respondents demonstrated better practices (54.20±12.5) as compared to female respondents (53.87±10.5), but the difference was not significant ( p=0.93). The mean percentage score of vendors’ practices in Dagoretti North was 54.52±11.2 while in Kibra it was 53.50±12.2; the difference was, however, not significant ( p=0.79). Milk safety practices increased with the level of education; respondents with tertiary education showed better practices (61.9±11.9) as compared to those with secondary education (53.57±11.3) and primary education (43.8±8.5), with their mean score difference being quite significant ( p=0.02 and F=4.641).

The majority of the respondents (91.9%) stated that the milk they sell using the vending machines was pasteurized, which is a practice that is compliant with the regulation. A good percentage of them (83.8%) confirmed that they use detergents while cleaning milk vending machines but none of them stated that the detergent was food grade, which is against the regulations. Most of the vendors (94.6%) stated that they can access adequate clean water for cleaning the milk vending machines. About 86.5% of the respondents said that they use tap water in cleaning the vending machines. Only 78.4% of them indicated that they clean the machines at least twice (morning and evening) daily with 21.6% of them only cleaning the vending machines once, which goes against the regulations.

More than half of the vending machines in the study (78.4%) displayed a temperature monitoring device; out of these, only 51.4% indicated that the milk was being stored at 0℃-4℃ while a big percentage of them (48.6%) being not sure about the temperature of storage or stored milk beyond 4℃ against the regulation. None of the vendors kept temperature monitoring records of daily temperature fluctuations in the vending machine as per the regulations. Only 8.1% of them had some cleaning and sanitation records. The majority of the respondents in this study (70.3%) were not transferring milk directly from the supplier’s original container to the dispenser as required. Regarding the duration for which milk is kept in the vending machines, only 73% of them stored milk in the machines for less than 24 hours as per the regulation with 27% of them not being compliant.

Only 18.9% of the respondents admitted to having undertaken medical tests for contagious diseases with 81.1% stating that they had not been medically examined to be free from contagious diseases. A good percentage of the respondents (64.9%) stated that they had not been trained for handling and operating milk vending machines and that they were relying on transferred knowledge on basic operations of the milk vending machines from the owners or previous operators. About 81.1% of the vending machine handlers had a valid operational license, however, 54.1% stated that their premises are not inspected periodically.

There was a positive correlation between milk hygiene knowledge and practices in this study. From Pearson’s correlation analysis ( Table 5), a strong positive correlation (r=0.626) existed between hygiene knowledge and practices, and it was highly significant ( p=0.000).

The correlation between knowledge and practices of milk vending machine handlers is illustrated in Figure 2. The dots inside the tables represent knowledge and practices scores. From the distribution of the dots as illustrated, a close association between the scores on knowledge and practices is indicted by their alignment towards a possible line of best fit showing that the knowledge of vendors closely influenced their practices.

Figure 3 shows variations of the mean percentage scores for hygiene knowledge and practices of milk vending machine handlers in the informal settlements of Nairobi. The green bars represent the variation in hygiene knowledge of handlers in Dagoretti North and Kibra; the blue bars represent variation in safety practices between handlers in the two study areas while the orange bar represents the overall hygiene knowledge and the red bar shows overall safety practices.

A Kenya Dairy Board representative, a regulatory officer, interviewed in this study stated that the institution offers licensing for milk vending machines. However, the exact statistics of how many vending machines have been licensed within Nairobi County at the time of the study was not provided. The regulatory officer also admitted to the availability of unlicensed milk vending machines being used in the market and that they constitute those machines that had been fraudulently obtained. The officer also stated that the institution does not have a structured means of training vendors on the operation of milk vending machines but a published quality document on regulatory requirements that vendors are expected to adhere to exists. The officer confirmed that they usually conduct inspections on milk vending machines to establish vendors’ operations and practices but that this has not been carried out intensively in the informal settlements, with the frequency of these inspections being described as routinely. According to the officer, measures taken on unlicensed vendors and those who do not comply with regulations include withdrawal of license and shutting down of business. The regulatory officer admitted to being aware of reported concerns on the quality of milk sold using milk vending machines. The officer, however, stated that Kenya Dairy Board has not yet begun carrying out regular and intensive surveillance tests to ascertain the safety of milk from milk vending machines and that the institution is in the process of building capacity to carry out these checks.

The level of knowledge on hygiene among milk vending machine handlers in this study was relatively low at a mean percentage of 68.83. In comparison with similar studies ( Mandefero & Yeshibelay, 2018), milk handlers had poor scores on overall food safety knowledge, personal hygiene, and temperature control. This is attributed to a lack of adequate training on milk hygiene knowledge among handlers. The level of hygiene knowledge among handlers in this study increased with increase in the level of education, this could be because one’s general understanding of hygiene and possible compromises to food safety improves as one progresses with education, and these findings are in tandem with those of other studies ( Blackmore et al., 2015), which found the knowledge of handlers being influenced by the level of education. The belief that pasteurized milk is safe cannot be contaminated by microorganisms alludes to a lack of enough knowledge on potential milk hazards among the respondents, a finding that is consistent with that of Lindahl et al. (2018) which revealed that only 9.1% of the respondents in that study believed that diseases can be transmitted by milk. In another study, Galičič et al. (2015) stated that one of the reasons milk vending machines have been highly embraced is the perception that the milk sold from these machines is of good quality and safe for consumption. While a majority of the vendors believe that milk storage facilities should always be kept clean using portable water, most of them do not know the type of detergents to use and could end up compromising the safety of the milk stored. While respondents understand that milk and milk vending machines should be purchased from licensed suppliers, however, the lack of awareness among vendors on the appropriate milk storage temperature is a major threat to milk safety. It is stated in the regulation that milk stored in the vending machine should be cooled and maintained at not higher than 4℃ ( KDB, 2018), and the control and monitoring of milk storage parameters such as temperature is critical in determining the level of microbial load in milk ( O’Connell et al., 2016). The majority of the milk handlers do not know that there are laws and regulations that guide the selling of milk using milk vending, which is a challenge that could be attributed to a lack of enough training and sensitization.

Milk safety is highly dependent on the handling practices of vendors, and several cases of milk contamination are attributed to poor handling practices ( Angelidis et al., 2016). Milk vending machine handlers in the current study demonstrated poor handling practices as indicated by the mean percentage score of 54.05. This finding is similar to other studies ( Abunna et al., 2019) which found the level of practices among milk vendors to be poor. The majority of the vendors in this study sold pasteurized milk via vending machines in line with the Regulatory Act on milk vending machines in Kenya ( KDB, 2018). The finding, however, contrasts with that of another study by Abunna et al. (2019), which found out that 81.5% of the vendors sold raw milk. Despite observing appropriate practices during cleaning of the vending machines, record keeping of routine hygiene and handling operations was a major challenge among handlers, which makes it hard for traceability in the event of safety concerns due to milk contamination ( Ndambi et al., 2020).

Vendors are required to routinely monitor temperature fluctuations and conduct periodic calibration of the vending machines while keeping these records as evidence during inspections. However, none of the vendors in this study kept monitoring and calibration records while some were not carrying out periodic monitoring and calibration. Efforts being put in place to reduce the possibility of cross-contamination in milk are not satisfactory, this is seen through the practice by 70.3% of the vendors storing milk in intermediate containers instead of transferring it directly from the supplier’s container to the vending machine. The lack of practices among the majority of the vendors to undertake medical tests for contagious diseases puts the consumer at risk of contracting these diseases through contaminated milk. Despite the need for vendors to be trained before they are issued with a license ( KDB, 2018), the majority of the vendors (64.9%) both with or without a license stated that they had not received any training and did not know that it existed, which is a drawback on the part of the regulator.

The level of practices among milk handlers increased with an increase in the level of education. This can be attributed to the increased hygiene knowledge among vendors, which is also influenced by education level, and has statistically been proven by the positive correlation between knowledge and practices of milk vending machine handlers in the current study. The overall poor milk handling practices can be attributed to a lack of training among a majority of the milk vending machine handlers as indicated in this study, which is a finding consistent with that of similar studies ( Amentie et al., 2016). The poor level of compliance with regulations by the milk vending machine handlers in this study can be attributed to the complexity of some regulatory standards that are seen to be either unclear to the vendors or out of touch with the reality of the informal settlements which are characterized by poor infrastructure and inadequate capital, therefore discouraging compliance ( Blackmore et al., 2015).

One limitation of this study is that it was not done over a longer follow up period to ascertain the exact impact of hygiene knowledge on practices of milk vending machine handlers. Another limitation is that some information obtained from the interviews on hygiene practices by respondents is prone to respondent bias since some may not have presented the true position on their milk handling practices due to personal fears hence compromising the authenticity of the study findings.

Zenodo: Data on hygienic knowledge and practices of milk vending machine handlers in the informal settlements of Nairobi Kenya. https://doi.org/10.5281/zenodo.5204466 ( Holi, 2021a).

This project contains the following underlying data:

-Dataset (sav)

Zenodo: Questionnaire on hygienic knowledge and practices of milk vending machine handlers in the informal settlements of Nairobi Kenya. https://doi.org/10.5281/zenodo.5508163 ( Holi, 2021b).

This project contains the following underlying data:

- Holi Regulator's Questionnaire.docx (a copy of the questionnaire for the regulator including the answers)

Zenodo: Questionnaire on hygienic knowledge and practices of milk vending machine handlers in the informal settlements of Nairobi Kenya. https://doi.org/10.5281/zenodo.5508163 ( Holi, 2021b).

This project contains the following extended data:

- Holi Knowledge and Practices Questionnaire.docx (a copy of the questionnaire for vendors)

Data are available under the terms of the Creative Commons Attribution 4.0 International license (CC-BY 4.0).