Introduction

Musculoskeletal disorders (MSDs) are a complex group of painful disorders of tendons, ligaments, joints, nerves and blood vessels. They occur in nine body parts: neck, shoulders, forearms, elbows, lumbar region, waist, wrists, thighs and knees, with varying frequency ^1,2. Therefore, MSDs are a major occupational health problem and one of the leading causes of disability worldwide ³.

According to the World Health Organization (WHO, 2021), an estimated 1,710 million people worldwide live with MSDs. Since 1990, low back pain has been the most frequent complaint, affecting 568 million people. Interestingly, available literature showed that the prevalence of these complaints in specific working populations and/or occupational sectors is significantly higher than in the general population ¹.

The most significant figures contributing to the global burden of occupational disease are ergonomic risk, injury risk, noise, fumes and gases ⁴. According to the International Labour Organization (ILO, 2019), workrelated fatalities account for 64 % in Asia, 11.8 % in Africa,

11.8 % in Europe, 10.9 % in America and 0.6 % in Oceania. These estimates reflect a serious endangerment faced by the working population worldwide ⁵. Regarding the prevalence of MSDs in workers, a Colombian research found that the frequency of MSDs in employees of a refrigerator factory was 60.8 %, out of whom 48.1 % presented only one affected body part ⁶. On the other hand, the frequency of MSDs in employees of a refinery in Lima, Peru, was 52.9 %, and the most affected body part was low back pain associated with disc herniation (25.1 %) ⁷.

The Ministry of Labor and Employment Promotion (MTPE) of Peru established a legal framework to standardize ergonomics in the workplace, including the "Occupational Safety and Health Law 29783" and the "Basic Standard 375-2008." The latter covers the parameters for load handling, work postures, and maximum and minimum loads for operators according to gender ⁸. An adequate ergonomic design in the work area guarantees better worker performance, as well as the epidemiological reduction of MSDs ⁹. Although there is legal support, not all companies strictly comply with the provisions of the MTPE or, alternatively, fail to control all the established points; therefore, these uncontrolled situations translate into ergonomic risk factors ^10,11.

Ergonomic risk refers to the probability of suffering an undesirable event at work; among the most frequent associated factors are awkward posture, repetitive motions, forceful exertions, inadequate furniture, sustained postures, high frequency of postures, among others. The REBA method analyzes the upper limb, trunk

and lower limb, and also evaluates the type of grip as well as the handling of loads. In this regard, a study conducted in workers of a garment manufacturing plant in Pakistan reported that the ergonomic risk level was predominantly high (40.3 %) ¹². Likewise, a study carried out in personnel who collect solid waste in Ecuador showed a medium level of ergonomic risk (48.4 %) ¹³. Finally, a study conducted in Peru by Arroyo-Castillo et al. ¹⁴ revealed that a very high level of ergonomic risk prevailed (38.46 %).

Severe and long-term MSDs could affect the quality of life, reduce work productivity, increase sick leave, shorten working life and lead to chronic work disability, as well as represent a major health challenge for individuals and health care systems worldwide ¹⁵. Kuorinka’s Standardized Nordic questionnaires measure the behavior of musculoskeletal symptoms and MSDs regarding the affected body part, event duration and intensity, and job change. Therefore, it is important to consider that ergonomic risk factors condition the occurrence, to a lesser or greater degree, of MSDs. Studies carried out in Pakistan and Ecuador confirmed that the ergonomic risk factor is significantly related to MSDs among operative workers ^12,16. It should be noted that, in order to learn more about the MSD phenomenon, it is important to consider the sociodemographic and labor profile of the workers since international and national studies show that sex ¹⁷, marital status ^18,19, job position and type of contract are related to MSDs ^2,17,20,21.

Good health is an essential requirement for the good performance of workers, so it is essential to ensure environments conducive to that end, as well as to provide constant training in posture hygiene and ergonomics. Therefore, as a first step, this research aims to analyze the relationship between ergonomic risk and MSDs among workers of a food company in the province of Callao, Peru, 2021.

Materials and methods

Results

Out of the total sample of 184 workers, 58.15 % were males, the mean age was 33.56 years, 42.39 % were cohabiting, 83.7 % had a full-time contract, 64.13 % were production operators, 43.48 % presented low ergonomic risk, and 79.89 % suffered a musculoskeletal disorder (Table 1).

Table 2 shows that the relationship between the ergonomic risk factor and MSDs was significant (p = 0.001), with a positive correlation strength of 0.301.

Table 3 shows that discomfort is related to sex, type of contract and job position. Older people had neck discomfort (p = 000), 84.42 % of workers with a full-time contract had musculoskeletal discomfort, and both machine and production operators had the same problem (p < 0.05).

Discussion

Among the main descriptive findings, it was evident that 43.48 % of food industry workers had a low level of ergonomic risk. This differed from the findings by Ashiq et al. ¹² in garment workers in Pakistan, who had long working hours and whose ergonomic risk level was predominantly high (40.3 %). Moreover, such results did not agree with those of a study conducted in Ecuador in solid waste collection workers, who were engaged in sweeping with a garbage tricycle in different work shifts and had a medium level of ergonomic risk (48.4 %) ¹³. Finally, a study carried out in percussionists in Lima, Peru, showed that the level of ergonomic risk was predominantly very high (38.46 %) ¹⁴. These disparities in findings could be due to the fact that the REBA method is mainly used for the analysis of awkward postures and not specifically for the evaluation of repetitive motions, and also because the type of place and activities could be ergonomically risky and require specific actions to minimize this risk, like the type of activities of the present work ²⁴.

Another finding was that 79.89 % of the workers developed MSDs, the back being the most affected body part, with 27.03 %. This finding agrees with that by Russo et al. ¹⁷, where the prevalence of MSDs and back pain in Italian workers accounted for 51.0 % and 46.1 %, respectively.

Another study agreed with the previous finding since it showed that Ecuadorian fruit pickers had more discomfort in the lower back or lumbar region (26 %) ¹⁶. A research conducted in workers of a refinery in Lima, Peru, demonstrated that 52.9 % developed MSDs and the trunk was the most affected body part ⁷. These percentage disparities could be due to the difference in the study participants’ perception of pain or discomfort, sample size, work environment and workload. Also, these findings confirm that MSDs remain one of the most common causes of disability worldwide and that low back pain is the most frequent condition as a result of workers’ activities ²⁵.

An important finding is that ergonomic risk is significantly related to MSDs in workers (r = 0.301), where people with very high ergonomic risk have discomfort. Ashiq et al. ¹² demonstrated that there was a strong positive correlation between ergonomic risk factor and MSDs (r = 0.9, p ≤ 0.001) in garment workers in a city of Pakistan. Likewise, the study by Pincay Vera et al. ¹⁶ concluded that there was a moderate positive correlation between ergonomic risk and MSDs and postures (r = 0.56, p ≤ 0.001). Similarly, according to the study by Ramírez Pozo ²⁶, both variables were significantly associated (r2 = 0.851, p = 0.05) in a population of workers of a refinery in Lima. This finding confirms that awkward postures or movements in workers’ activities can cause MSDs, and these differences in the correlation strength of the findings are possibly due to the type of work, the available assessment tools, and the strategies for the evaluation of ergonomic risks that require specific skills and adequate training to be selected and used appropriately ¹⁷.

Regarding the relationship between the secondary variables and MSDs, sex was associated with MSDs (p = 0.015) and males had greater discomfort. This result was compared with that of the studies conducted by Russo et al. ¹⁷ and Ramírez Pozo ²⁶, which showed that sex is significantly related to MSDs. However, only the study by Russo et al. ¹⁷ claimed that females were the most affected by MSDs. These results confirm that nowadays both females and males perform the same work tasks and face the same likelihood of developing MSDs, which may be due to differences in social roles, activities and behaviors ²⁷. However, because of biological divergences, males’ muscles are more developed than females’, with thicker muscle fibers and less water; therefore, the female musculoskeletal system more is prone to suffer injuries. It should be noted that more males than females developed discomfort in the present study, possibly because more males participated in the research.

Age was not significantly related to MSDs (p = 0.061). This agrees with the studies carried out in Peru by ZamoraChávez et al. ²⁸ and by Ramírez Pozo ²⁶. On the other hand, MSDs were significantly associated with marital status (p = 0.011), i.e., those who had a partner (married and cohabiting) presented pain. This finding is supported by two studies, one conducted in Peru (18) and another one in China ¹⁹, which showed that marital status was related to MSDs (p ≤ 0.001). Barzideh et al. ²⁹ explained that married workers fulfill not only their job but also their responsibility to the family. In addition, their rest time is relatively less than other workers’.

Job position was related to MSDs (p = 0.001) since production operators stated pain in the right shoulder and wrist. This finding is similar to that of the research carried out by Garzón Duque et al. ²¹, Njaka et al. ² and Russo et al. ¹⁷, who showed that the job position was related to MSDs and confirmed that operators or manual workers presented more conditons. This is due to the frequent bending or squatting activities and lifting heavy objects from the floor, so the lower back accounted for the highest rate of MSDs. Even prolonged standing at work has a strong association with foot and leg discomfort. This is a deviation from the ergonomic principles of work, which establish that tasks should be adapted to the workers, who are also supposed to work in neutral postures and in comfort zones ³⁰.

The type of contract was related to MSDs (p = 0.001), which is explained by the fact that people with a fulltime contract have more pain than tenured workers. This finding agrees with that of the study by Dong et al. ²⁰, who noted that employment status was significantly associated with MSDs. This could be because temporary or contract employees experience more job insecurity than permanent or tenured employees. In addition, job insecurity has been identified as an important job stressor that negatively affects the psychological and physical health and well-being of employees, thus leading to the onset or aggravation of MSDs ³¹.

In terms of the study limitations, the cross-sectional design allowed us to describe associations but not to draw causal inferences about the effects of the different variables of MSDs. Another limitation was that the study ignored the quantitative interactions between the occupational, psychosocial and demographic factors. A prospective cohort study design may be needed in the future to provide stronger research evidence. As in most cross-sectional studies, self-reported data was collected, so it is likely that the study subjects may have provided vague or exaggerated responses about their MSDs. This study has key strengths as it is one of the first research evidence on MSDs among food industry workers.

In conclusion, ergonomic risk was related to MSDs and showed a low positive correlation. Moreover, sex, marital status, job position and type of contract were related to MSDs, and the most affected groups were males, those who had a partner, operators and contract employees. On the other hand, it was evident that most food industry workers had a low level of ergonomic risk and developed MSDs, with greater discomfort in the back.

Based on the findings, it is recommended that further studies focus on analyzing the effectiveness of current evaluation methodologies and strategies used to assess biomechanical/ergonomic risk factors on a periodic basis, considering the most affected population according to the sociodemographic and occupational profile. These innovative strategies should be primarily aimed at improving our understanding of emerging occupational risks that may be associated with MSDs and thus developing workplace interventions to improve the process of occupational risk assessment and management, so that to implement them in health surveillance systems.

Also, workers’ and employers’ awareness of the appropriate ergonomic and personal measures necessary to improve the safety and well-being of workers should be increased. Finally, it is recommended to formulate policies concerning worker safety and company productivity, which would help safeguard workers and employers from health deviations and economic loss in terms of lost workdays, compensation and low productivity. Moreover, said policies would help improve working conditions, such as the work environment, to enable workers to perform a variety of recreational activities and adjust the operating cycle.