The relationship between the level of postural stress, Musculoskeletal Disorders, and chronic fatigue: A case study in the dairy industry.

BACKGROUND: Dairy industry workers face numerous ergonomic risk factors in their workplace, including improper posture, manual material handling, and musculoskeletal disorders (MSDs). Fewstudies have been conducted on the correlation of postural stress, MSDs, and chronic fatigue among workers in the dairy industry. OBJECTIVE: This study aimed to investigate the relationship between the level of postural stress, MSDs, and chronic fatigue in a dairy company. METHODS: In this cross-sectional study, 260 male workers were included in the research based on specific inclusion criteria. The Cornell Musculoskeletal Discomfort Questionnaire, Chalder Fatigue Scale, and a researcher-made demographic questionnaire were used to collect data. The posture of workers was evaluated using RULA and REBA software, and the evaluation of the manual lifting of loads was assessed using the WISHA lifting calculator. Finally, the collected data were entered into the SPSS software version 26.0 and analyzed. RESULTS: The findings revealed a significant statistical relationship between the level of postural stress and chronic fatigue and a significant positive correlation between MSDs and chronic fatigue. Furthermore, a statistically significant relationship was observed between MSDs, chronic fatigue, and ergonomics training experience. CONCLUSIONS: The results obtained in this study support the notion that high levels of postural stress and MSDs can produce an increase in chronic fatigue among workers, and lack of ergonomics training for workers can increase both MSDs and chronic fatigue. Therefore, it is necessary to carry out intervention measures in the field of ergonomics management in similar industries through the implementation of ergonomic intervention programs with a focus on proactive and preventive measures and the use of participatory ergonomic programs and educational demands assessment.

Exploratory analysis using machine learning algorithms to predict pinch strength by anthropometric and socio-demographic features.

Objectives. This study examines the role of different machine learning (ML) algorithms to determine which socio-demographic factors and hand-forearm anthropometric dimensions can be used to accurately predict hand function. Methods. The cross-sectional study was conducted with 7119 healthy Iranian participants (3525 males and 3594 females) aged 10-89 years. Seventeen hand-forearm anthropometric dimensions were measured by JEGS digital caliper and a measuring tape. Tip-to-tip, key and three-jaw chuck pinches were measured using a calibrated pinch gauge. Subsequently, 21 features pertinent to socio-demographic factors and hand-forearm anthropometric dimensions were used for classification. Furthermore, 12 well-known classifiers were implemented and evaluated to predict pinches. Results. Among the 21 features considered in this study, hand length, stature, age, thumb length and index finger length were found to be the most relevant and effective components for each of the three pinch predictions. The k-nearest neighbor, adaptive boosting (AdaBoost) and random forest classifiers achieved the highest classification accuracy of 96.75, 86.49 and 84.66% to predict three pinches, respectively. Conclusions. Predicting pinch strength and determining the predictive hand-forearm anthropometric and socio-demographic characteristics using ML may pave the way to designing an enhanced tool handle and reduce common musculoskeletal disorders of the hand.

Analyzing the influential factors of process safety culture by hybrid hidden content analysis and fuzzy DEMATEL.

Due to the complex nature of safety culture and process industries, several factors influence process safety culture. This paper presents a novel framework that combines the hidden content analysis method with Decision Making Trial and Evaluation Laboratory (DEMATEL) and Fuzzy logic to achieve a comprehensive set of influential factors and their relationship. The proposed methodology consists of two primary stages. Firstly, combined methods of literature review and Delphi study were used to identifying influential factors of process safety culture. Secondly, the Fuzzy-DEMATEL approach is employed to quantify and determine the relationships between different influential factors. A diverse pool of experts' opinions is leveraged to assess the impact of each factor on others and process safety culture. In the first stage, 18 factors identified as influential factors on process safety. The findings of second stage revealed that eight variables were identified as causes, while ten variables were classified as effects. Also, the Organization management's commitment to safety factor had the greatest influence among all of the factors. As well as, the most significant interaction was associated with the risk assessment and management aspect. The integrated approach not only identified the influential factors, but also elucidates the cause-effect relationships among factors. By prioritizing factors and understanding their interconnections, organizations can implement targeted safety measures to improve process safety culture. Its effectiveness in quantifying qualitative data, identifying influential factors, and establishing cause-effect relationships make it a valuable tool for enhancing safety culture in process industries.

Stress influence on real-world driving identified by monitoring heart rate variability and morphologic variability of electrocardiogram signals: the case of intercity roads.

Objectives. This study examines which of the heart rate variability (HRV) and morphologic variability (MV) metrics may have the highest accuracy in different stress detection during real-world driving. Methods. The cross-sectional study was carried out among 93 intercity mini-bus male drivers aged 22-67 years. The Trillium 5000 Holter Recorder and GARMIN Virb Elite camera were used to determine heart rate and vehicle speed measurements along the path, respectively. We considered the HRV and MV metrics of electrocardiogram (ECG) signals including the mean RR interval (mRR), mean heart rate (mHR), normalized low-frequency spectrum (nLF), normalized high-frequency spectrum (nHF), normalized very low-frequency spectrum (nVLF), difference of normalized low-frequency spectrum and normalized high-frequency spectrum (dLFHF), and sympathovagal balance index (SVI). Results. The analysis showed that the HRV metrics mHR, mRR, nVLF, nLF, nHF, dLFHF and SVI are effective in mental stress detection while driving as compared to rest time. We obtained a high accuracy of stress detection for MV metrics as compared to the traditional HRV analysis, of approximately 92%. Conclusions. Our findings indicate that driver stress could be detected with an accuracy of 92% using MV metrics as an accurate physiological index of the driver's state.

A comparative investigation of machine learning algorithms for predicting safety signs comprehension based on socio-demographic factors and cognitive sign features.

This study examines whether the socio-demographic factors and cognitive sign features can be used for envisaging safety signs comprehensibility using predictive machine learning (ML) techniques. This study will determine the role of different machine learning components such as feature selection and classification to determine suitable factors for safety construction signs comprehensibility. A total of 2310 participants were requested to guess the meaning of 20 construction safety signs (four items for each of the mandatory, prohibition, emergency, warning, and firefighting signs) using the open-ended method. Moreover, the participants were asked to rate the cognitive design features of each sign in terms of familiarity, concreteness, simplicity, meaningfulness, and semantic closeness on a 0-100 rating scale. Subsequently, all eight features (age, experience, education level, familiarity, concreteness, meaningfulness, semantic closeness, and simplicity) were used for classification. Furthermore, the 14 most popular supervised classifiers were implemented and evaluated for safety sign comprehensibility prediction using these eight features. Also, filter and wrapper methods were used as feature selection techniques. Results of feature selection techniques indicate that among the eight features considered in this study, familiarity, simplicity, and meaningfulness are found to be the most relevant and effective components in predicting the comprehensibility of selected safety signs. Further, when these three features are used for classification, the K-NN classifier achieves the highest classification accuracy of 94.369% followed by medium Gaussian SVM which achieves a classification accuracy of 76.075% under hold-out data division protocol. The machine learning (ML) technique was adopted as a promising approach to addressing the issue of comprehensibility, especially in terms of determining factors affecting the safety signs' comprehension. The cognitive sign features of familiarity, simplicity, and meaningfulness can provide useful information in terms of designing user-friendly safety signs.

An integrated DEMATEL-ANP approach for identification and prioritization of factors affecting fall from height accidents in the construction industry.

Objectives. The decision-making trial and evaluation laboratory (DEMATEL) technique integrated with the analytic network process (ANP) is used for determination and prioritization of cause-effect relationships among factors affecting construction falls. Methods. Considering the 135 fall accidents collected between 2013 and 2018 from 15 residential construction projects, 70 factors and sub-factors affecting the occurrence of construction falls were determined based on safety experts' opinions. Questionnaires based on the former and the latter were then distributed among 10 occupational health and safety specialists to determine the effectiveness of the factors. The interactions and important degree of each factor are specified, using the DEMATEL-ANP approach. Results. Findings showed that organizational factors and their sub-factors have the greatest impact on construction falls and were considered as causal variables (D - R > 0), while individual and environmental factors were considered as the effect variables (D - R < 0). The results of prioritization using the ANP method showed that the work platform altitude, psychological/occupational stresses and interactions were ranked as the first through third priorities affecting the falls, respectively. Conclusions. It is necessary to implement a systematic strategy to reduce the unsafe conditions in construction projects and to pay more attention to organizational factors.

Relationship between risk perception toward hearing conservation and using hearing protection devices among offset printing workers in Tehran province, Iran.

The way workers perceive noise exposure can play an important role in the adoption of safety behaviors. Therefore, the determination of the relationship among risk awareness, behavior, and exposure can be an extremely important issue in controlling noise exposure. The aim of this study was to investigate the association between risk perception and practice of workers. Workers from 16 printing houses in Tehran province participated in present study. A questionnaire was used for determining the level of risk perception and practice about hearing conservation. The results revealed a significant relationship between risk perception and safety behavior adoption (P < 0.001). A positive and significant correlation was found between these two variables (P < 0.001; rs = 0.912). Also, the results showed that workers with hearing impairment had a better practice. In addition, attention should be paid to preventive principles and encouragement of hearing protection devices usage among employees.

The effect of job security on safety behavior with the moderating role of salary: a structural equation model.

This study aimed to model the relationship between job security and safety behavior with the moderating role of salary on the workers of the construction project of Qom (Iran) Subway. After determining the subjects of the study, the questionnaires on safety behavior and job security were completed by subjects. Also, the salary of the subjects was determined. Structural equation modeling used smart partial least squares software. The results revealed that job security had a direct and significant correlation with safety compliance, safety participation and safety behavior (p < 0.001). The salary as a moderator had a positive and significant effect on the relationship between job security and safety behavior (p < 0.05). Generally, it can be deduced that job security had a positive impact on safe behaviors, and the salary as a moderator enhanced this impact. To improve safety behavior in the workplace, employers should increase the job security of workers.

Normative data for handgrip strength in Iranian healthy children and adolescents aged 7-18 years: comparison with international norms.

BACKGROUND: Grip strength is an essential component of physical fitness. The objective of this study was to develop normative handgrip strength data for Iranian healthy boys and girls comparing their handgrip strength with international reference values. METHODS: Handgrip strength was measured in 2637 healthy children/adolescents (1391 boys and 1246 girls), aged 7-18 years, using a standard adjustable Jamar hand dynamometer (Model 5030 J1, Sammons Preston Rolyan, Bolingbrook, IL, USA). Body mass (kg) and stature (cm) were measured and body mass index was computed in kg/m2. The sample was stratified by gender, age, and hand preference. RESULTS: Handgrip strength increased with age and was considerably higher in boys than in girls for all age groups (p < 0.001). Grip strength had a parallel and linear growth for both genders until the age of about 11 years and showed a steeper upward slope in boys than in girls thereafter. The findings of the current investigation were significantly different from those of the previously published normative data, especially for boys over the age of 12 years and girls in the age range of 7-18 years (p < 0.001). This difference was mainly in such a way that the Iranians had lower handgrip strength. CONCLUSIONS: The differences between present results and those of similar available in the literature in this field emphasize the significant role of using normative data specific to a particular population in research or clinical settings.

Analysis of hand-forearm anthropometric components in assessing handgrip and pinch strengths of school-aged children and adolescents: a partial least squares (PLS) approach.

BACKGROUND: The purpose of this study was to examine the influence of hand-forearm anthropometric dimensions on handgrip and pinch strengths among 7-18 years children and adolescents and to investigate the extent to which these variables can be used to predict hand strength. METHODS: Four types of hand strengths including handgrip, tip to tip, key, and three-jaw chuck pinches were measured in 2637 healthy children and adolescents (1391 boys and 1246 girls) aged 7-18 years using standard adjustable Jamar hydraulic hand dynamometer and pinch gauge. A set of 17 hand-forearm anthropometric dimensions were also measured with an accurate digital caliper and tape measure. RESULTS: No significant differences were found between the hand strengths of boys and girls up to the age of 10 years. Gender related differences in handgrip and pinches were observed from the age of 11 years onwards, with boys always being stronger. The dominant hand was stronger than the non-dominant hand (8% for handgrip and by about 10% for all three types of pinches). The strongest correlations were found between the hand length and hand strengths (r > 0.83 for handgrip and three all pinches; p < 0.001, 2-tailed). Based on the partial least squares (PLS) analysis, 8 out of 17 anthropometric indices including hand length, hand circumference, thumb length, index finger length, middle finger length, and forearm length had considerable loadings in the PLS analysis, which together accounted for 46% of the total variance. CONCLUSIONS: These results may be used by health professionals in clinical settings as well as by designers to create ergonomic hand tools.

Identification, Selection and Prioritization of Key Performance Indicators for the Improvement of Occupational Health (Case Study: An Automotive Company).

Regarding the important role of occupational health in the continuous improvement of organizations, the aim of this study was to identify, select and prioritize key indicators for improvement of occupational health in an automotive company. This cross-sectional descriptive study was carried out in three stages. First, a semi-structured interview as well as an inspection and a review of the company's documentation and studies were carried out, and a set of key indicators were identified and selected. Then, the validity of the indicators were determined by experts (N = 11). Following that, the indicators were prioritized based on SMART criteria. Following the study framework, we collected a set of indicators that included 45 health indicators and 17 educational ones. The results of examining their content validity showed that among the 45 primary health indicators and 17 educational ones, 12 and 9 indicators had acceptable validity, respectively, and a total of 21 indicators were suggested for the purpose of the study by the expert team. The results of prioritizing showed that the leading indicator such as the percentage of corrective and preventive health actions done with the weight of 0.146 was the first priority. A set of key indicators was proposed according to the results, based on the objective of the study, which can help managers and industrial hygiene experts to assess performance in the automotive industry.

Relationship between Noise Annoyance and High Blood Pressure in Workers Exposed to Chronic Noise Among the Workers of an Automotive Industry.

BACKGROUND: Chronic exposure to noise in workplaces is one of the most important physical agents that affects workers' health and causes social and individual problems. The aim of this study was to investigate the relationship between noise annoyance and blood pressure (BP) of workers of an automotive industry. METHODS: In this cross-sectional study, 250 workers were randomly selected. The subjects were classified in two groups based on the exposure to sound pressure levels lower and higher than 85 dB (106 and 144 workers, respectively). In this study, BP was measured using an ALPK2 mercury pressure gauge. To measure annoyance levels, an annoyance questionnaire containing a numerical question numbered 0-11 was used. RESULTS: The mean age of the subjects was 36.19 (±3.75) years. The results showed that the systolic (SBP) and diastolic blood pressure (DBP) of the subjects exposed to the sound pressure levels higher than 85 dB were significantly higher than those exposed to a sound pressure level lower than 85 dB (P < 0.01). Also, the results of the multivariate regression showed a significant relationship between the annoyance and DBP and SBP caused by chronic exposure to noise and sound pressure levels (P < 0.01). CONCLUSION: The results of this study showed that the annoyance caused by exposure to chronic noise in the workplace causes stress in the workers and, in the long term, could increase the risk of high SBP and DBP.

Relationship Between Noise Annoyance and Cognitive Performance in Automotive Workers Exposed to Chronic Noise.

Among the most important complaints of people exposed to noise are the feelings of resentment and annoyance, and the changes in mental conditions, which are among the main psychological consequences affecting the concentration and accuracy of workers. This study was designed to investigate the relationship between annoyance and cognitive performance of workers exposed to chronic noise. This is a descriptive-analytical study conducted on workers in an automotive company. Three hundred workers exposed to noise were entered into the study in two groups: administrative (150 people) and industrial (150 people). The Tower of London and the Stroop computerized psychological tests were used to determine the cognitive status of the workers, and a questionnaire with numbered questions (numbered 1 to 11) was used in order to determine their level of annoyance. There was a significant correlation between the workers' cognitive performance and annoyance levels (P value <0.001). Linear regression results showed that cognitive performance had a significant relationship with the received sound intensity, while the workers' annoyance had a significant relationship with cognitive performance only in the number of wrong answers, the number of unanswered questions, and the number of correct answers in the Stroop test (P value <0.001). The researchers concluded that exposure to chronic noise in work environments could bring about occupational annoyance, and consequently, cognitive disorders, which could increase the risk of errors. More studies are needed to further explore this relationship.

Effect of Co-Driver on Job Content and Depression of Truck Drivers.

BACKGROUND: Since the presence of a co-driver can be considered as a companion, partner, or friend for a driver through eliminating driver's loneliness, it plays a significant role in health and safety of drivers. The objective of this study was to investigate the effect of co-drivers on depression and occupational stress on male truck drivers. METHODS: This study was an interventional case-control study. Seventy truck drivers were selected and divided into two groups: case (33 truck drivers with co-drivers) and control (37 truck drivers without co-drivers). Two Goldberg depression inventories (for evaluating driver's depression) and the Karasek job content questionnaire (for evaluating driver's job stress) were used to collect data which were completed by interview. RESULTS: The results showed that job content values for the case group were higher in all dimensions except job nature. The comparison of the percentages showed significant difference between two groups. Depression rate in drivers with co-driver is truly less than depression rate in drivers without co-driver. There was significant positive relationship between dimensions of job content and depression rate. CONCLUSION: According to the results of this study, it can be claimed that a co-driver decreases stress and loneliness of drivers, as well as increases work performance and job satisfaction, and, in turn, leads to a decrease in job-related depression.

Thoracic Kyphosis Angle in Relation to Low Back Pain among Dentists in Iran.

BACKGROUND: Non-specific low back pain (LBP) has a direct impact on the quality of life, active days at work and health care costs. AIM: This study was conducted to determine the relationship between LBP and thoracic kyphosis angle among dentists. MATERIAL AND METHODS: This cross-sectional and descriptive-analytical study carried out in the form of census among 84 dentists employed in a specialised clinic in Iran. Dentists LBP prevalence and intensity and thoracic kyphosis angle were evaluated respectively with the self-administered body map questionnaire, visual analogue scale and flexicurve ruler. Statistical data analysis was done using SPSS software, version 22. RESULTS: The data showed that the prevalence of LBP in dentists was 44.9% and intensity of LBP was reported about 71.9 ± 19.34. Pearson correlation coefficient between thoracic kyphosis angle and dentist's characteristics was not significant except for work experience. The single linear regression model showed that 1.3% of thoracic kyphosis angle changes was positively dependent on LBP. Also, the present study proved that thoracic kyphosis angle changes were positively dependent to 2.6%, 10.8% and 5.7 percent of age, work experience and Body Mass Index (BMI), respectively. CONCLUSION: Despite the lack of significant statistical relation between LBP and thoracic kyphosis angle, there is a high prevalence and intensity of LBP among Dentists. To reduce the risk of work-related LBP among dentists, managing factors such as BMI, work postures and exercises during work should be taken into consideration.

Safety climate and prediction of ergonomic behavior.

One of the most important ways to prevent accidents is to consider safety climate or culture. Moreover, some studies suggest that behavior contributes to 86%-96% of all injuries. This cross-sectional study took place in an Iranian petrochemical company in 2010. Vinodkumar and Bhasi's safety climate questionnaire and an ergonomic behavior sampling checklist were the data collection tools. Cronbach's α for questionnaire reliability was .928. With reference to the results of a pilot study, a sample of 1755 was determined for behavior sampling. We used principal component analysis (PCA) to derive the coefficient of paths in the path model and the Anderson-Rabin method to calculate factor scores. The results showed that safety climate was an effective predictor of ergonomic behavior (p < .01). They also showed the importance of decreasing the number of workers with negative safety climate. Moreover, it is necessary to promote workers' ergonomic behaviors in the workplace.

Adverse effects of formaldehyde vapor on mouse sperm parameters and testicular tissue.

BACKGROUND: Formaldehyde (FA), one of the simplest organic molecules, is a flammable, pungent, irritating and colorless gas. This study aimed to investigate the effects of various concentrations of FA vapor on sperm parameters and testicular tissue. MATERIALS AND METHODS: In this experimental study, we randomly assigned 36 adult male mice to one control and two experimental groups (n=12 for each group). The control group (C) did not receive FA. Group F1 (low concentration) was exposed to 10 ppm FA vapor and the F2 (high concentration) group was exposed to 20 ppm FA vapor. FA was administered for ten days, eight hours per day for both groups. At the end of the exposure period, half of the animals in each group were sacrificed 24 hours after exposure to detect any short-term effects; the rest of the mice were sacrificed 35 days later to assess for long-term effects. Sperm parameters were analyzed by Computer-assisted Sperm Analyzer (CASA) and histological changes determined. In addition, we studied changes in testosterone hormone. Data were analyzed by one-way ANOVA followed by the Scheffe test using SPSS software. RESULTS: Long-term effects of FA in the experimental groups included significant reductions in sperm cell numbers and sperm viability. A drastic reduction in progressive motility and increased abnormal sperm percentage (p<0.001) compared with the control group was also noted. Histological study of testes specimens in the experimental group revealed displacement of germinal cells, along with degeneration of Leydig cells and seminiferous tubules. CONCLUSION: Exposure to FA vapor can destroy testicular structure and decrease percentages of concentration, viability, normal morphology, and progressive motility, in addition to increasing the percentage of immotile sperm.