ABSTRACT
Introduction:
Sanitation workers do physically demanding job like collecting, segregating, and disposing waste. They are prone to develop musculoskeletal problems. The study aimed to measure sociodemographic profile and musculoskeletal morbidity among sanitation workers employed by the Thiruvananthapuram corporation.
Objectives:
To estimate the prevalence of musculoskeletal pain among, sanitation workers employed by Thiruvananthapuram corporation and factors associated with it.
Methodology:
A cross-sectional study was conducted in Thiruvananthapuram corporation. The designated sanitation workers employed by Thiruvananthapuram corporation were study population. 165 workers sampled out of 641 workers, working for not less than 12 months from before initiation of study, were included in study and were selected by simple random sampling. Data were collected using semistructured questionnaire, entered into MS Excel, analysed appropriately using appropriate statistical software. The prevalence of musculoskeletal pain during work during the last 1 year was assessed using Standardised Nordic questionnaire adopted in local language Malayalam. Socioeconomic factors and risk factors related to nature of work were also studied. Association between sociodemographic factors, risk factors and musculoskeletal morbidity was also tested statistically.
Results:
Of total study participants, 73 (44.2%) had felt knee pain in any of the knees or both knees, 53 (32.3%) had low back pain during the past 1-year period, followed by ankle pain and shoulder pain which 34 (21.6%) and 29 (17.9%) of participants reported. Overall, pain in any one of the body part was reported by 111 (67.3%) participants.
Conclusion:
The study revealed high burden of musculoskeletal pain like knee pain, low back pain, ankle and shoulder. There is a need to take measures to reduce musculoskeletal pain and morbidities among sanitation workers employed by the corporation. Mostly, they are of older age, majority female gender and are prone to develop diseases of musculoskeletal system. Better ergonomic practices, mechanisation and health education will be beneficial to them.
Keywords: Knee pain, low back pain, musculoskeletal morbidity, musculoskeletal pain, sanitation workers, solid waste management
Introduction
Musculoskeletal morbidity among sanitation workers is a pressing public health concern, particularly in the context of solid waste management. World Health Organization mention musculoskeletal disorders are a leading cause of disability worldwide, with low back pain being the single leading cause of disability globally and between one in three to one in five people live with a painful and disabling condition worldwide.[1] Inadequate ergonomic practices and poor job design are common predisposing factors. Previous studies have highlighted a global prevalence of musculoskeletal disorders among sanitation workers with significant implications on their health and productivity. Musculoskeletal disorders are major public health challenge in population engaged in physically demanding tasks. Sanitation workers are tasked with crucial responsibility of handling solid waste which involves manual handling of heavy loads, repetitive motions and awkward postures. These factors lead to high burden of musculoskeletal morbidity, leading to chronic pain, reduced mobility and diminished quality of life.[2]
Local and regional studies on the topic had come up with alarming results. Thiruvananthapuram corporation is not an exception. There are studies conducted in bigger cities as well as other cities in Kerala. A study conducted in Thrissur reveled huge morbidity among female workers especially and duration of work was a major risk factor. In Chennai, a prevalence of 67.3 was reported and working condition and bad ergonomics were major risk factors.[3] The study was conducted to generate evidence in a more local context and to bring in light the burden of musculoskeletal pain related morbidity among sanitation workers in Thiruvananthapuram corporation. This might stir further explorations and serve as a foundation stone. This research aims to quantify the extent of musculoskeletal morbidity in this population and identify potential risk factors that may help to propose targeted interventions.
Objectives
To estimate the prevalence of musculoskeletal pain among, designated sanitation workers employed by Thiruvananthapuram corporation and the factors associated with it.
Methodology
Study setting: This study was conducted in Thiruvananthapuram Corporation, between January 2020 and December 2021.
Study population: Sanitation workers employed by Thiruvananthapuram corporation were the study population. The workers designated as sanitation workers by the corporation are those workers engaged in activities pertaining to cleaning, collecting and segregation of waste including solid waste.[4]
Inclusion criteria: All sanitation workers employed in the corporation and working for not less than 12 months.
Exclusion criteria: Temporary workers not regularly working since past 12 months were excluded. Workers who did not consent for study were excluded.
Sample size: 12 month period prevalence of Musculoskeletal pain among municipal solid waste workers was taken as 70%, based on a study conducted at Chennai municipal corporation, titled ‘Musculoskeletal disorders among municipal solid waste workers in India: A cross-sectional risk assessment[5] using which the sample size was calculated by the formula for cross-sectional surveys and minimum sample size required calculated was 165, relative precision used was 10%, and confidence interval was set at 95%.
Sampling technique: Simple random sampling was done by using computer-generated random numbers in Microsoft Excel from staff list of sanitation workers in Thiruvananthapuram corporation. There were 641 sanitation workers meeting the inclusion criteria.
List of workers for sampling purpose was obtained from corporation health office. It was serially numbered, and 165 random numbers generated using MS Excel.
Study variables: Sociodemographic variables such as age, gender, color of ration card, and education were self-reported. Height and weight were measured, and BMI was calculated. Variables in standardised Nordic questionnaire were also used.
Data collection tools and techniques
Information about site of work of each study participant sampled and health section in which the person works was obtained from the corporation health office. There are 100 wards in Thiruvananthapuram municipal corporation, in which there are 14 health circles each manned by a health inspector, supervised by a team of health supervisors, one each for group of 4 circles. The health officer of corporation is in charge of the health section, and it carries out public health activities such as solid waste management and sanitation. Health inspector or junior health inspector of the concerned health section where each study participant in the sample works was informed before data collection visit and permission to interview concerned workers was obtained before visit. All necessary permissions from corporation health officer were obtained beforehand.
Written informed consent in local language was obtained from study participants, and signature was obtained. Information was collected through face-to-face interview of the study participants by the interviewer after meeting them at their work place.
Nordic questionnaire for musculoskeletal survey adopted into Malayalam language was used for data collection relating to musculoskeletal pain. A semistructured questionnaire was used to record socio demographic variables, like age of the participant in completed years, gender of the study participant (male, female, transgender), and the colour of the ration card as an indication of socioeconomic status, with white and blue ration cards representing APL (Above poverty line) and red and yellow representing BPL (below poverty line household, factors related to musculoskeletal pain, from the study participants. Anthropometric measurements were measured as per standard measurement guidelines.
Data analysis: Quantitative variables were expressed in mean and standard deviation and qualitative variables in proportion where ever applicable. Appropriate tables and graphs are drawn to represent the findings. Associations between the factors were tested using appropriate test of significance (chi-square test). Fisher’s exact test was used if any cell in the contingency table had an expected value less than 5.
The strength of association was expressed as odds ratio with 95% confidence interval.
Musculoskeletal pain across different individual body parts, overall prevalence and limitation in doing day to day activities was calculated. Then, the final dataset was used for Analysis. Data were Entered Into MS Excel and analysed appropriately using trial version SPSS v25.
Ethics approval: The study protocol was submitted before institutional research board and human ethics committee of the institution where the researcher was affiliated during that period. After getting ethics committee, clearance and obtaining permission from corporation health officer study was commenced. All participants were given the option of refusal to take part in the study during the introductory conversation. Informed consent was obtained from the study participants, and all financial expenses were borne by the investigator.
Results
Sociodemographic details of the participants
The median age of the study participants was 50 years with inter quartile range of 11. The 25th and 75th percentile values were 45 years and 56 years. The minimum age was 25 years, and the maximum age was 60 years. The sociodemographic profile of the study population is described in Table 1.
Table 1.
Sociodemographic characteristics of study participants
| Sociodemographic characteristics | Categories | N (%) |
|---|---|---|
| Age group | <40 | 10 (6.06%) |
| 41-45 | 38 (23.03%) | |
| 46-50 | 43 (26.06%) | |
| 51-60 | 30 (18.18%) | |
| >60 | 44 (26.66%) | |
| Sex | Male | 67 (41%) |
| Female | 98 (59%) | |
| Total | 165 (100%) | |
| Ration card colour | White | 136 (82.42%) |
| Blue | 16 (9.69%) | |
| Pink | 13 (7.87%) | |
| Total | 165 (100%) | |
| Education level | Illiterate | 4 (2.42%) |
| Primary school | 9 (5.45%) | |
| Middle school | 37 (22.43%) | |
| High school | 103 (62.43%) | |
| Intermediate | 7 (4.24%) | |
| Graduate | 5 (3.03%) | |
| Total | 165 (100%) | |
| BMI | <18.5 | 25 (15.15%) |
| 18.5-22.9 | 91 (55.76%) | |
| 23-24.9 | 8 (4.84%) | |
| >25 | 40 (24.25%) | |
| Total | (100%) |
Musculoskeletal pain among study participants
Out of total study participants (n = 165), 111 (67.3%) participants reported to have had pain in at least one of the 9 different body parts, and the overall prevalence of musculoskeletal pain was 67.3%. The results are summarised in Table 2.
Table 2.
Musculoskeletal pain prevalence among study participants
| Musculoskeletal pain (12 months) | Frequency (n=165) | Percentage (%) |
|---|---|---|
| Present | 111 | 67.3 |
| Absent | 54 | 32.7 |
| Total | 165 | 100 |
Musculoskeletal pain across body parts
The distribution of musculoskeletal pain across different body regions is shown in Table 3. The rows and columns in the table are totally mutually exclusive. Hence, adding values in all cells do not give 165. Each row each cell represents the number and percentage in that particular category out of the total sample size (N) 165. For limb regions, pain on either sides or both sides is quantified, and in the table, pain on both sides represented only in that category. They are not included in the either left or right side categories again. This was to avoid duplication. Neck and trunk regions do not have left and right categorization. Only the total number of individuals reporting pain and its percentage was given.
Table 3.
Distribution musculoskeletal pain among study participants (n=165) across body parts
| Body part | Only on Right side, n (%) | Only on Left side only, n (%) | On Both sides* n (%) | Total# n (%) |
|---|---|---|---|---|
| Shoulder pain | 11 (6.7%) | 2 (1.2%) | 16 (9.7%) | 29 (17.6%) |
| Elbow pain | 5 (3.0%) | 1 (0.6%) | 4 (2.4%) | 10 (7.8%) |
| Wrist pain | 3 (1.8%) | 0 (0%) | 4 (2.4%) | 7 (4.2%) |
| Knee pain | 12 (7.3%) | 5 (3%) | 56 (33.9%) | 73 (44.2%) |
| Ankle pain | 14 (8.5%) | 8 (4.8%) | 12 (7.3%) | 34 (21.6%) |
| Hip pain | 0 (0%) | 0 (0%) | 2 (1.2%) | 2 (1.2%) |
| Neck pain | - | - | - | 1 (0.6%) |
| Upper back pain | - | - | - | 2 (1.2%) |
| Lower back pain | - | - | - | 53 (32.2%) |
• number of participants with pain on both right and left sides and not on any single side.
# Sum of study participants with pain on a) either only right or left and b) both right and left side body part
Some participants reported pain in multiple body parts too; proportion of such participants with pain in combination across multiple body parts is not calculated. If a participant had both knee and shoulder pain, he/she is counted in both knee pain and shoulder pain prevalence calculation. This approach was used to get the prevalence of pain across each region separately. All the categories are mutually exclusive.
Study participants with musculoskeletal pain during 12 month and had that pain during the past 7 days
The proportion of study participants who reported pain during last 12-month period in any one of the individual body parts surveyed and was having pain during the past 7 days was estimated and is given in Table 4. The rows and columns in the table are mutually exclusive, each row the total number of participants reporting pain during past 12-month period in that category given in brackets in the first column of that row and in the other cells in that row gives the numbers and percentages out of the n given in first cell of that row.
Table 4.
Musculoskeletal pain during past 7 days among those who had pain during past 12 months period
| Body part | Only on Right side, n (%) | Only on Left side, n (%) | On Both sides n (%) | Total n (%) |
|---|---|---|---|---|
| Shoulder pain (n=29) | 10 (34.4%) | 4 (13.7%) | 13 (44.8%) | 27 (93.1%) |
| Elbow pain (n=13) | 6 (46.1%) | 2 (15.3%) | 2 (15.3%) | 10 (76.9%) |
| Wrist pain (n=7) | 4 (57.1%) | 1 (14.2%) | 1 (14.2%) | 6 (85.7%) |
| Knee pain (n=73) | 10 (13.7%) | 6 (8.2%) | 44 (60.3%) | 60 (82.2%) |
| Ankle pain (n=34) | 1 (2.9%) | 0 (0%) | 1 (2.9%) | 2 (5.9%) |
| Hip pain (n=2) | 0 (0%) | 0 (0%) | 2 (100%) | 2 (100%) |
| Neck pain (n=1) | - | - | - | 0 (0%) |
| Upper back pain (n=2) | - | - | - | 2 (100%) |
| Lower back pain (n=53) | - | - | - | 44 (83%) |
Limitation in day to day activities due to musculoskeletal pain
All study participants who had reported musculoskeletal pain during past 12-month period were asked about any limitation in performing daily activities at home or work due that pain. 55 (75.34%) study participants with knee pain, 32 (60.37%) study participants with low back pain and 24 (14.5%) study participants with shoulder pain had limitation in daily activities due to that pain.
The results are summarized in Table 5.
Table 5.
Limitation in daily activities at home or work due to musculoskeletal pain
| Body part | Number of study participants with limitation in daily activities due to pain in the region/body part. |
|---|---|
| Neck (n=1) | 1 (100%) |
| Shoulder (n=29) | 24 (82.75%) |
| Elbow (n=13) | 11 (84.61%) |
| Wrist (n=7) | 3 (42.85%) |
| Upper back (n=2) | 1 (50%) |
| Lower back (n=53) | 32 (60.37%) |
| Hip (n=2) | 1 (50%) |
| Knee (n=73) | 55 (75.34%) |
| Ankle (n=34) | 0 (0%) |
Association between musculoskeletal pain and sociodemographic factors
Musculoskeletal pain was reported higher by female participants compared with male participants (P value < 0.001). Other factors like age, education, socioeconomic status (measured by color of ration card), BMI and history of accidents were statistically tested for association with musculoskeletal pain. The results are summarized in Table 6.
Table 6.
Association between musculoskeletal pain and sociodemographic factors, BMI, accidental injuries
| Musculoskeletal Pain | Chi-square | OR (95%CI) | P | |||
|---|---|---|---|---|---|---|
|
| ||||||
| Yes (%)* | No (%)* | |||||
| Gender | Male (n=67) | 34 (50.7) | 33 (49.3) | 13.99 | 0.28 (0.14,0.56) | <0.001 |
| Female (n=98) | 77 (78.6) | 21 (21.4) | ||||
| Age | >50 years (n=74) | 54 (73.0) | 20 (27.0) | 1.98 | 1.61 (0.83,3.16) | 0.184 |
| <50 years (n=91) | 57 (62.6) | 34 (37.2) | ||||
| BMI | <23 (n=64) | 46 (71.9) | 18 (28.1) | 0.93 | 1.40 (0.71,2.77) | 0.393 |
| >23 (n=99) | 64 (65.4) | 35 (34.6) | ||||
| Education | <high school (n=115) | 80 (69.6) | 35 (31.4) | 0.91 | 1.40 (0.69,2.81) | 0.370 |
| >/= high school (n=50) | 31 (62.0) | 19 (38.0) | ||||
| SES | White ration card (n=136) | 92 (67.6) | 44 (32.4) | 0.05 | 1.10 (0.47,2.56) | 0.824 |
| Others (n=29) | 19 (65.5) | 10 (34.5) | ||||
| Accidents | Yes (n=4) | 3 (67.1) | 1 (22.9) | 0.111 | 1.47 (0.15,14.49) | 1.000# |
| No (n=141) | 108 (75.0 | 53 (25.0) | ||||
*percentages are row percentages
#fisher’s exact test
Discussion
Musculoskeletal pain prevalence
Overall 12 month prevalence of musculoskeletal pain was very high (67.3%). It was more in body parts like shoulder, knees, lower back, and ankles.
Similar studies conducted globally reflect similar results.
A study conducted among municipal solid waste workers in Chennai corporation reports the prevalence of musculoskeletal pain among municipal solid waste workers in any one or more joints was estimated as 70%.[6]
Another study conducted in Mumbai reported the 12-month prevalence of MSDs was higher among waste pickers (79%) compared with controls (55%) particularly in the lower back (54–36%), knee (48–35%), upper back (40–21%) and shoulder (32–12%) regions.[3]
In Shiraz, Iran, a study by Manzoor Ziaei, Alireza Choobineh et al.[5] on individual, physical and occupational risk factors of musculoskeletal disorders among municipal solid waste collectors, 92.5% participants reported pain in any one of the 9 body parts during the last 12 months. Lower back and knee pain and injuries were severe. In another study conducted in Tehran, Iran, by Mehrdad et al.,[7] the prevalence of musculoskeletal pain was 65%.
A meta-analysis on occupational health outcomes among sanitation workers conducted by HH Oza and MG Lee[8] reported evidence for increased occurrence of musculoskeletal disorders among sanitation workers.
The results of present study are in lieu with studies conducted globally. There is high burden of musculoskeletal pain and disability among sanitation workers.
Out of the total 165 study participants, 98 (59%) were females and 67 (41%) were males. Gender was identified a major risk factor for musculoskeletal pain. The prevalence of musculoskeletal pain among females was significantly higher than males (P value < 0.001) with odds ratio of 0.28 (CI-0.14 to 0.56). Ageing is proven to be associated with musculoskeletal morbidities among women. A study conducted in Chennai among municipal solid waste workers reported gender a major risk factor for musculoskeletal pain (OR-2.53).[6] There was no significant association between BMI and musculoskeletal pain.
There was higher prevalence of long-term pain, acute pain as well as limitation in daily activities due to that pain among sanitation workers, which can be directly responsible for chronic musculoskeletal morbidity and sanitation workers being socioeconomically backward and an apparently neglected group of population needs care and assistance throughout their life in most appropriate and affordable manner, in connection with alleviating musculoskeletal pain, that needs medical management and rehabilitation. The study can possibly further generalized into all those who do manual labour, especially cleaning activities, including older women doing household chores, since the pattern of work of both groups of people are similar, and on the gender basis majority are women, and further studies are needed in this context. There is scope for the family physician in this context to play an important role in identifying such problems, solving them in a holistic manner and providing long-term continuum of care for pain relief and prevention of further disability among them.
Conclusion
The burden of musculoskeletal pain is high among municipal sanitation workers, prevalence across any body part is 67.3%. Recently, many more people are being engaged in sanitation work and cleaning drives as part of public initiatives undertaken in municipal areas as well in rural areas and people are also being recruited on daily wages for sanitation work. They are at risk of musculoskeletal pain and morbidity due to this work. The study gives evidence for the high prevalence of pain during the last 12 months and very high proportion of such people were experiencing pain during the past 7 days before the survey and a majority of them reported limitation in doing day to day activities due to that pain. This can have implications in further disability and handicap and there is scope for family physician and general practitioner in providing holistic care by giving treatment using standard pain management practices which can often extend to a longer term due to its chronicity and the intermittent exacerbations of the musculoskeletal condition which needs to be prevented by timely intervention. There is a need for health system in urban areas to screen for musculoskeletal problems and provide timely intervention and efforts must be taken by health section of the corporations itself in this matter to look after the health of its own sanitation workers.
Limitations
Pain was self-reported. There are chances of recall bias in the reporting of pain especially the 12 months pain. Also the presence of pain at same site during past 7-day period on the same site can help in better recall since presence of recent pain in a particular site might help remembering pain in that region during recent past. The study is not free of limitations. It is done on sanitation workers in a single corporation, on a fixed group with small sample size, so cannot be generalized. There are chances of over reporting of pain by the participants due to their nature of work, other factors like education and socioeconomic status might have impacted the study results. Also more analysis could be done in identifying risk factors and a detailed study into quality of life could have been done.
Conflicts of interest
There are no conflicts of interest.
Funding Statement
Nil.
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