Introduction

Psychosocial risks, particularly stress, are emerging risks in the workplace. The work environment has a major influence on the mental health and well-being of each employee [1]. This work environment has positive effects when work provides satisfaction and contributes to personal self-fulfillment, or negative effects provoked by situations of stress, inadequate working patterns and schedules, possible situations of abuse and/or harassment [2].

Occupational stress is the reaction that people may have when confronted with work demands and pressures that challenge their coping ability [3]. Recent changes in how work is managed, characterized by tighter control of individual and collective productivity and by attempting to function with minimal manpower, create somatic and cognitive disorders in workers.

Occupational stress has consequences for both workers and companies [4]. Indeed, the conditions of stress at work are capable of creating diseases with more or less serious consequences on the biological, hormonal [5], physical, psychological, and social level of the individual [6,7]. Those psychological consequences are measured through emotional stability [8]. The homeostatic adaptations to stress are regulated by the central nervous system, the neuroendocrine system, and the immune system, which constitute an integrated biological circuit under the control of genes [9]. It has been reported that the work activity, especially that performed during the night, is able to influence the sleep-wake cycle, favoring the development of insomnia. Insomnia would subject the worker to such a stressful condition that it would encourage undesirable behaviors such as the use/abuse of psychotropic substances. A greater propensity of night workers to consume alcoholic beverages than those who work during the day, often in binge-drinking mode, has been reported in the literature [10].

Indeed, inadequate management of occupational stress can lead to a considerable decrease in workers’ performance, burnout [11], an increase in absenteeism from work, and use of psychoactive substances [12–14] like tobacco and alcohol abuse. There is a correlation between occupational stress and alcohol and tobacco abuse [15], especially in rotating or night workers [16,17].

When employee performance declines, it leads to reduced productivity, accidents, and injuries, which result in compensation and treatment costs for injured workers [18–20]. Work-related stress is also a risk for cardiovascular and psychiatric disorders [21,22]. The prevalence of work-related stress varies from one region to another, from one industry to another [3], and according to the tool used to measure stress. In Europe, occupational stress is the second most common work-related health problem, affecting 28% of employees [1]. In most countries, occupational stress has been most studied in the service sector, in particular health care, banking, and transport [23–25]. However, there is a dearth of literature in the industrial sector, which nevertheless may be at high risk of stress.

Cotton ginning sector is one such sector, where, due to market competitiveness in Sub-Saharan Africa, there is great pressure to achieve results. Workers also have other exposures that may cause stress including cotton dust, noise, shift work, and night work [16,26,27]. Faced with these factors, workers may be at risk of occupational stress in the course of their work. Owing to the lack of data on occupational stress, we sought to determine the prevalence and factors associated to occupational stress among cotton gin workers in Benin in 2019.

Materials and methods

Results

Workers characteristics

The flow diagram of the participants ultimately included in the study is shown in Fig 1. A total of 1883 workers were included and 1709 (90.8%) were male (Table 1). Their median age was 38 years with an interquartile range (IQR) of 28 to 49 years. The majority of workers were Beninese (99.4%). The majority (82.5%) of participants did not have university-level education and the majority had a partner (76.0%). Few workers had permanent employment status (11.8%) or worked in administrative roles (11.7%). Of included participants, the median (IQR) time at their current role was 3 (2 to 12) years, at the current company was 4 (2 to 12) years, and working in the cotton sector was 5 (2 to 16) years. Most participants were exposed to high levels of noise in the workplace (78.8%). A minority of participants were current smokers or had a history of smoking (14.8%).

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Fig 1. Flow diagram of recruitment of participants at included ginning plants.

https://doi.org/10.1371/journal.pone.0269498.g001

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Table 1. Distribution of cotton mill workers by characteristics (N = 1883).

https://doi.org/10.1371/journal.pone.0269498.t001

Prevalence of occupational stress and other outcome measures

Overall, 1464 of 1883 (77.7%, 95% CI: 75.8% to 79.6%) of workers met the definition for our primary outcome of experiencing occupational stress. The median score for psychological demand was 25 (IQR: 23 to 28) and for decision latitude was 60 (IQR: 52 to 66). Only 131 (7.0%) of participants scored low (<20) on the psychological demand component and 304 (16.1%) scored high (≥70) on the decision latitude component. A large proportion of workers felt they had low recognition at work (1692; 89.9%) Despite these scores, only a small minority of participants reported having low colleague support (13; 0.7%) or having low hierarchical support (37; 2%). Table 2 shows the prevalence of psychological and organizational constraints by ginning factory and region and Fig 2 shows the distribution of workers according to the Karasek dial, with psychological demand on the y-axis and decision latitude on the x-axis.

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Fig 2. Distribution of workers according to psychosocial constraints using the Karasek dial.

https://doi.org/10.1371/journal.pone.0269498.g002

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Table 2. Distribution of scores for psychological and organizational constraints.

All values are N (%).

https://doi.org/10.1371/journal.pone.0269498.t002

Factors associated with occupational stress

In univariable analysis, several factors were associated with occupational stress, however few remained associated after multivariable adjustment (Table 3). The strongest factor associated with occupational stress was being an occasional vs. permanent worker, where those who were occasional workers had 6.43 (95% CI 4.18 to 9.88) times higher odds of occupational stress. Age less than 38 years was associated with 0.55 (95% CI 0.41 to 0.76) the odds of occupational stress as compared to persons aged 38 years and older. Other factors associated with occupational stress included high intensity physical activity at work (1.33, 95% CI 1.03 to 1.73), working in production vs. administration (1.59, 95% CI 1.03 to 2.45), spending fewer than 4 years at the current work location (1.60, 95% CI 1.05 to 2.44), and scoring low for recognition at work (1.53, 95% CI 1.04 to 2.23).

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Table 3. Results of regression analyses for the outcome of occupational stress.

https://doi.org/10.1371/journal.pone.0269498.t003

Discussion

To our knowledge, this is the first study conducted in Benin to assess occupational stress among cotton ginning plants workers. We found 77.7% of included participants had occupational stress and it was most strongly associated with being an occasional vs. permanent worker. This prevalence of occupational stress is higher than those observed in other sectors of activity. This includes estimates of 27.3% in an insurance company in Benin [30], 54.6% in a port environment in Abidjan, Côte d’Ivoire [31], and 17% in employees across 14 companies in the Tunisian private sector [32]. Our estimates are closer to levels of stress found in the secondary sector of activity, such as a prevalence of 69% among firemen in Senegal [33] and 52% among migrant workers in Cameroon [34].

The strengths of the study lie in the large sample size, the methodology for the selection of participants, national representation of the study, the involvement of all socio-professional categories of the companies, and the use of a validated questionnaire. Indeed, the Karasek questionnaire is the most widely used tool in epidemiological surveys involving a large population, such as the SUMER survey [28,35].

A limitation of our study is that the psychometric qualities of the Karasek questionnaire are more effective in the service sector (interpretation of certain items) [23] whereas our study took place in the industrial sector. The cross-sectional nature of the study is also a limitation. However, the prevention of occupational stress cannot succeed without knowledge of its determinants in each sector, and little data are available in the cotton industry. The variability of the sectors of activity and the types of stress questionnaires used in other studies limits the generalizability of the results.

Being an occasional worker was strongly associated with occupational stress. The occupational status of the worker, especially in an industrial environment, determines the types of tasks that they are assigned. Thus, occasional workers in these ginning enterprises are more subject to tasks of physical strength, requiring rhythmic work where decision latitude is low. In addition, occasional workers are more subject to job insecurity because they generally only work for six months. Several authors have shown the relationship between working conditions, job insecurity and job stress [36–38]. Jigan et al found an association between the level of stress and many factors including, the type of work and the professional title, in an oil sector [22].

Age under 38 years appeared to be a protective factor for occupational stress after adjustment for other factors in our study. This may be contrary to expectation as older workers could be more confident in their work and less prone to work-related stress as they age, whereas young workers are still trying to find a work-life balance [22]. However, Go et al. showed in nurses that as age increased, work was perceived as more stressful [39]. This difference could be explained by our consideration of the time of workers in their position, company, and sector, which seemed to indicate higher levels of stress for newer workers.

The significant association between the role of the worker (production vs. administration) and occupational stress has also been found in other sectors of activity such as insurance and the oil sector [30,40]. In our study, workers in the production sector had nearly 60% increased odds of being stressed compared to workers in the administration sector. Our results corroborate those of Magroun et al. who found a significant association between occupational stress and four sectors of activity: wood production, furniture manufacture, poultry farming and the plastics and rubber industry [32] as well as the findings of Jigan et al [40].

High-intensity physical activity at work was significantly associated with occupational stress. Boudet et al., after considering the different factors of variation of stress, showed a protective effect of moderate physical activity towards occupational stress [41]. Physical activity is often associated with a reduction in stress and constitutes a method of stress control. However, in the professional context, when the physical workload is intense, it can constitute a risk factor for stress. In fact, in this context, intense physical activity reflects an overload of work or an unsuitability of the work for the person.

Working in the plants for less than 4 years is associated with occupational stress. The association between low job experience and occupational stress was also shown by Jianga et al. in oil industry workers [40]. Work experience allows the worker to better manage stressful situations and to better understand the assigned tasks. Workers who have worked for a shorter period of time lack work experience, and therefore need to improve their ability to perform the necessary work tasks. Because of their aspirations for success, the need to perform tedious tasks, and competition among colleagues, they are more likely to experience job stress. This finding is not consistent with the results of Lompo et al in the banking sector [42] and Diedhiou et al in firefighters [33] which may be attributed to differences between the study subjects and the type of work.

Low recognition at work doubled the risk of job stress. Hinson et al. found a similar result and showed that low recognition at work was an additional reason for job strain [30].

In an industrial environment, noise exposure is frequent, and its intensity varies from one workstation to another. Apart from the effects on hearing, some studies indicate that occupational noise exposure may increase the risk of cardiovascular diseases, such as hypertension, coronary heart disease and stroke [43–45]. Some authors, such as Kivimäki et al, have concluded that the risk of coronary heart disease increases with occupational stress [21], while Selander et al and Eriksson et al have shown the synergistic action of noise and occupational stress on cardiovascular risk [46,47]. The results of the present study indicate that occupational noise exposure is associated with occupational stress in univariable analysis but not in multivariable. This could be due to power or suboptimal classification of noise exposure, as it was a classification based on workstation reporting.

Shift work is a frequent form of organization in industrial environments to facilitate the continuity of production. The association found in univariable analysis between shift work and occupational stress has been confirmed by other authors. Indeed, authors have found that occupational stress and shift/night work were associated, both independently and in combination, with an increased risk of poor mental health [22]. Working irregular shifts over a long period of time not only affects the physical health of workers but can also reduce work efficiency and lead to higher absenteeism, which increases the vulnerability of workers. In nurses, there is an association between rotating shift work and increased occupational stress [48]. Among health care workers, the best shifts in terms of reducing the incidence of shift-related disorders are the morning and evening shifts. The night shift is the worst shift in this regard [49]. Therefore, it is suggested that managers make decisions to limit exposure to night work. However, the lack of an association between occupational stress and shift work after adjusting for other factors in our study could be justified by the interactions between the variables.

Consideration of this occupational stress in the improvement of working conditions is necessary. Indeed, the occupational stress component has been integrated into the actions of the OHSC of plants. Thus, an action plan has been set up to map noise, to reinforce the control of the wearing of hearing equipment, to reinforce the personnel entities, and to improve the system of listening to the workers in plants. Several methods for managing work-related stress have been developed around the world: aromatherapy, bibliotherapy, cognitive behavioral therapy, exercise, alternative medicine, mindfulness, stress management, and sensory intervention [50]. Experimentation with some of these techniques in an intervention program is being considered for this population of workers.

Conclusion

The prevalence of occupational stress among workers in cotton ginning plants is very high. Occasional work, low workplace recognition, and working in production were the main factors associated with stress. Interventions to address or mitigate the impact of these factors on stress should be studied, such as the implementation of stress education, workplace support and recognition programs, and measures to improve job security.

Supporting information

Acknowledgments

Our thanks go to the managers and workers of the companies for giving us the opportunity; and to the doctors, nurses, epidemiologists of CNHU-PPC and LEMACEN/FSS who invested in this work.

Thanks to L’Oréal-UNESCO for the Young Talents for Women in Science 2021 Award, Sub-Saharan Africa Region, which is a personal support to Dr. Adjobimey for her research work in textile industries.