Objectives: The aim of this study was to compare the psychophysiological strain related to a conventional shift schedule and new ergonomically improved two- and three-shift schedules using heart rate variability (HRV) analysis. The specific aim was to determine whether the introduced ergonomic shift arrangement had any positive effects on the psychophysiological strain such as increased HRV or decrease in the sympathovagal balance of the autonomic nervous system (ANS). Methods: Questionnaire data and 24-hour HRV recordings were gathered from 48 female shift-working nurses once while working the conventional shift schedule (baseline) and again after one year working an ergonomic shift schedule during the morning shift. Results: Comparisons between conventional and ergonomic shift schedules (baseline and follow-up, respectively) revealed significant differences in frequency-domain parameters. Implementing an ergonomic shift schedule resulted in decreased normalized low frequency (LF) power, increased normalized high frequency (HF) power, and decreased LF/HF ratio at the beginning of the shift. Furthermore, at baseline, mean RR interval, root mean square of successive RR interval differences (RMSSD) and normalized HF power were increased at the end of the shift compared with the values at the beginning of the morning shift. In contrast, at the follow-up, LF power was increased between the end and beginning of the morning shift. Conclusions: The psychophysiological strain measured by HRV analysis was lower at the beginning of the work shift for the ergonomic shift schedules compared with the conventional schedule. This indicates that an ergonomic shift schedule may have a positive effect on the ANS recovery occurring between successive work shifts.(J Occup Health 2013; 55: 225-233)
Objectives: This study among Japanese dual-earner couples examined the independent and combined associations of work-to-family conflict (WFC) and family-to-work conflict (FWC) with psychological health of employees and their partners and the relationship quality between partners. Methods: The matched responses of 895 couples were analyzed with logistic regression analysis to examine whether there were differences among the four work-family conflict groups (i.e., no conflict, WFC, FWC and both conflicts groups) in terms of own psychological distress, social undermining (i.e., negative behaviors directed toward the target person) reported by partners and partner's psychological distress. The no conflicts group was used as the reference group. Results: The both conflicts group had the highest odds ratios for own psychological distress and social undermining towards the partner for both genders. In addition, for husbands, the both conflicts group had the highest odds ratio for partner's psychological distress, whereas for wives, it did not. Conclusions: Dual experiences of WFC and FWC have adverse associations with psychological health of employees and relationship quality between partners of both genders. In addition, dual experiences in husbands have an adverse association with psychological health of their partners (i.e., wives), whereas this is not the case for wives.(J Occup Health 2013; 55: 234-243)
Objective: Children are universally considered to be the most important asset for any nation. The main aims of the present study were 1) to investigate the causation of discomfort related to working postures 2) to assess the physiological strain among the child farmers and 3) to assess the thermal stress during work in an agricultural field. Methods: For this study, 120 child agricultural workers and 120 control subjects aged 10-16 years were selected randomly, and a detailed posture analysis was performed among them by REBA and OWAS methods. The Modified Nordic Questionnaire was applied to assess the discomfort felt among both groups of workers. Physiological assessment of workload was carried out by recording the heart rate and blood pressure of the workers prior to work and just after work in the field. Results: Child agricultural workers suffered from pain especially in the low back (98%), knees (88%), hands (82%), shoulder (77%) and neck (68%). Among the agricultural activities in potato cultivation, the child potato workers, felt discomfort during spading (99%), sprinkling water (90%) and picking crops (87%). The post-activity heart rate of the child agricultural workers was 170.1 beats/min, whereas the systolic and diastolic blood pressures were 129.0 and 67.0 mm/Hg respectively. Conclusions: Most of the agricultural activities in potato cultivation were strenuous ones that affect the children, who suffered from acute pain and discomfort for a long period of time, which mainly hampers and restricts their education.(J Occup Health 2013; 55: 244-258)
Objectives: Pushing tasks are functional activities of daily living. However, shoulder complaints exist among workers exposed to regular pushing conditions. It is crucial to investigate the control of shoulder girdles during pushing tasks. The objective of the study was to demonstrate scapular muscle activities and motions on the dominant side during pushing tasks and the relationship between scapular kinematics and muscle activities in different pushing conditions. Methods: Thirty healthy adults were recruited to push a four-wheel cart in six pushing conditions. The electromyographic signals of the upper trapezius (UT) and serratus anterior (SA) muscles were recorded. A video-based system was used for measuring the movement of the shoulder girdle and scapular kinematics. Differences in scapular kinematics and muscle activities due to the effects of handle heights and weights of the cart were analyzed using two-way ANOVA with repeated measures. The relationships between scapular kinematics and muscle activities were examined by Pearson's correlation coefficients. Results: The changes in upper trapezius and serratus anterior muscle activities increased significantly with increased pushing weights in the one-step pushing phase. The UT/SA ratio on the dominant side decreases significantly with increased handle heights in the one-step pushing phase. The changes in upward rotation, lateral slide and elevation of the scapula decreased with increased pushing loads in the trunk-forward pushing phase. Conclusions: This study indicated that increased pushing loads result in decreased motions of upward rotation, lateral slide and elevation of the scapula; decreased handle heights result in relatively increased activities of the serratus anterior muscles during pushing tasks.(J Occup Health 2013; 55: 259-266)
Objectives: Previous studies in firefighters have been contradictory regarding their course of lung function over time. The aim of this ongoing study is to investigate how changes in lung function over time in male metropolitan firefighters compare with those in population controls, and to explore associations between firefighters' use of personal respiratory protection devices during occupational exposures and their risk of accelerated lung function decline. Methods: A prospective comparison of FEV1 (forced expiratory volume in 1 second) and FVC (forced vital capacity) was performed between 281 firefighters and 933 population controls. Logistic regression models were used to compare changes from baseline of FEV1 and FVC after 3 years and risk of accelerated decline between the cohorts. Within the firefighter cohort, risk of accelerated decline was compared between subgroups based on use of respiratory protection devices. Results: Controls showed similar mean annual declines for FEV1 and FVC across age categories, whereas firefighters aged <45 years showed increasing values over time (p=0.040). Firefighters had a lower odds of accelerated FEV1 decline compared with controls (OR=0.60, 95%CI 110.44; 0.83), but firefighters who never or rarely used respiratory protection during fire knockdown had a higher odds of accelerated FEV1 decline compared with those who used it often or frequently (OR=2.20, 95%CI 1.02; 4.74). Conclusions: Younger generations of firefighters showed an increase in lung function relative to older colleagues, while population controls consistently showed decline of lung function across all ages. Firefighters who reported to be incompliant in using respiratory protection showed an increased risk of accelerated FEV1 decline.(J Occup Health 2013; 55: 267-275)
Objectives: In spite of the high prevalence of low back pain (LBP) and presenteeism previously observed among nurses, no study has assessed the risk of presenteeism specifically due to LBP in nursing staff. Therefore, aim of the present study was to assess prevalence and risk factors of presenteeism due to LBP among hospital nursing personnel. Methods: 174 female nurses underwent a clinical interview and filled in a questionnaire on sociodemographics, LBP symptoms and associated sickness absence, mental symptoms, burnout and on exposure to workplace organizational, psychosocial and ergonomic factors; 111 subjects affected by LBP were included in the analysis. The effect of sociodemographic and workplace characteristics on presenteeism was examined through multivariate Poisson robust regression models. Results: Prevalence of presenteeism due to LBP was 58%, with wide differences between registered nurses and nursing aides (p=0.001). Only a few workplace factors were significantly associated with presenteeism, including frequent stooping, which decreased the risk of presenteeism, and good working climate and procedural justice, which increased it. Conclusions: Presenteeism due to LBP was very high among registered nurses and was influenced only by workplace, but not by sociodemographic characteristics. Presenteeism due to LBP among registered nurses should be closely monitored, and effort should be made to reduce it to prevent future work disability associated with LBP.(J Occup Health 2013; 55: 276-283)
Objectives: We sought to clarify the association of occupational formaldehyde exposure with DNA strand breaks, chromosome damage and DNA-protein crosslinks (DPCs) in the peripheral blood (PB) lymphocytes of plywood workers. Methods: We determined Olive tail moment (OTM) values, micronucleus (MN) frequencies and DPC rates of the PB lymphocytes in 178 workers divided into control and lower and higher exposure groups according to their current formaldehyde exposure levels and examined the association of each end point with formaldehyde exposure levels and with the number of work years. We also examined each end point in an additional 62 workers before and after an 8-hour formaldehyde exposure for validating the association. Results: OTM values increased significantly in the two exposure groups compared with those in the control group (p<0.05 for both) and were associated with increasing formaldehyde exposure levels (ptrend=0.002), while MN frequencies increased with increasing numbers of work years (ptrend<0.001). The dynamic study showed that OTM values and DPC rates increased after an 8-hour formaldehyde exposure compared with those before the exposure (p<0.001, p=0.019, respectively), that, in a dose-dependent manner, OTM values were associated with formaldehyde exposure levels during work hours (p=0.005) and that MN frequencies before and after the 8-hour work exposure were associated with numbers of work years (p=0.029, p<0.001, respectively). Conclusions: We found a dose-response relationship between the current formaldehyde exposure levels and DNA strand breaks and between duration of exposure and chromosome damage in the PB lymphocytes of plywood workers.(J Occup Health 2013; 55: 284-291)
Objectives: The aim of this study was to ascertain the actual state of toner exposure of workers who handle toner. Methods: Personal exposure measurements were conducted on workers handling toner in which the respirable dust (RD) concentration by work type was determined. Targeted work types consisted of “machine recycling”, “toner manufacturing”, “toner research/development”, “machine design/development” and “servicing.” The implementation period lasted from April 2003 to March 2011, and measurements were conducted annually. The measurement method conformed to the Japanese Working Environment Measurement Standards (new standards adopted starting in 2005). Results: Comparing the RD concentrations for fiscal year 2003 by work, significant differences were found between machine recycling and the other four work types, as well as in toner manufacturing and the other four work types. Similarly, based on the new legislative standards applied in Japan from fiscal year 2005, significant differences were found between machine recycling and the other four work types, as well as in toner manufacturing and the other four work types. Discussion: It is clear that workers engaged in machine recycling and toner manufacturing are exposed to toner, and that a certain level of exposure is continuing. Although it cannot be said that workers involved in toner research/development, machine design/development and servicing have no toner exposure, the concentration is of an extremely low level. Conclusions: At present, toner exposure levels by work type can be divided into two groups—one consisting of machine recycling and toner manufacturing, and the other consisting of toner research/development, machine design/development and servicing.(J Occup Health 2013; 55: 292-300)
Objectives: The aim of this study was to evaluate the effect of occupational exposure in the occurrence of lung cancer. Method: Three-hundred lung cancer cases diagnosed between September 1, 1999, and September 31, 2007, and 300 healthy controls were enrolled in this case-control study. Life-long occupational history, gender, age, exposure to asbestos, comorbidities, and smoking status were collected. Results: The mean age of the 300 lung cancer cases was 60.3 ± 9.9 year (91.7% male and 8.3% female), and the mean age of healthy control group was 60.4 ± 10.5 year (95.0% male and 5.0% female). The most frequent histological types were squamous (172, 57.3%), adeno (69, 23.1%), and small cell (37, 12.3%). There was an increased risk of lung cancer occurrence among agriculture workers (OR=1.89, 95% Cl=1.17-2.98) (p=0.009). Inorganic dust exposure (OR=1.81, 95% Cl=1.0-3.25) (p=0.049) and organic dust exposure (OR=1.89, 95% Cl=1.0-3.59) (p=0.05) were found to be related with high frequency of having lung cancer. Conclusion: Workers who had occupational exposure to organic and inorganic dust, especially in the agricultural field, had higher risk of lung cancer occurrence when compared with office workers.(J Occup Health 2013; 55: 301-306)
Objectives: This study aimed to clarify the association between long working hours and short sleep duration among Japanese workers. Methods: We selected 4,000 households from across Japan by stratified random sampling and conducted an interview survey of a total of 662 participants (372 men; 290 women) in November 2009. Logistic regression analyses were performed using “sleep duration <6 hours per day” as a dependent variable to examine the association between working hours/overtime hours and short sleep duration. Results: When male participants who worked for ≥7 but <9 hours per day were used as a reference, the odds ratio (OR) for short sleep duration in those who worked for ≥11 hours was 8.62 (95% confidence interval [CI]: 3.94-18.86). With regard to overtime hours among men, when participants without overtime were used as a reference, the OR for those whose period of overtime was ≥3 hours but <4 hours was 3.59 (95% CI: 1.42-9.08). For both men and women, those with long weekday working hours tended to have a short sleep duration during weekdays and holidays. Conclusions: It is essential to avoid working long hours in order to prevent short sleep duration.(J Occup Health 2013; 55: 307-311)
Objectives: High incidences of silicosis are continuing to be reported among the agate workers of small-scale household agate processing units in the Khambhat region of Gujarat (India). The objective of this study was to investigate reasons behind the high prevalence of silicosis, and factors affecting the noncompliance with preventive methods among agate workers. Methods: The study was conducted using a questionnaire-based structured interview method among 82 agate workers in Khambhat to assess their awareness level about silicosis and preventive methods, existing morbidity, worker's attitude toward health, and the prevalence of actual use of preventive methods to avoid silica exposure. Results: The majority of the workers (55%) were aware of silicosis and the harmful effects of silica dust exposure (72%) and knew about simple preventive methods to avoid silica dust exposure (80%), but only a minority of the workers (22%) were actually using the simple and available dust-preventive methods. Only 9% of the uneducated workers were using the preventive methods, while usage was higher among educated workers (28%), who had five or more years of schooling, and these workers had fewer health conditions or less morbidity. Gender and job duration had no effect on the usage of dust-preventive methods. Conclusions: The data suggest that noncompliance with use of dust-preventive methods could be the reason behind the higher prevalence of silicosis and health morbidity in agate workers, and that years of schooling plays a significant role in the increased usage and self-compliance with dust-preventive methods among agate workers.(J Occup Health 2013; 55: 312-317)
Objectives: Savinase is one of the endopeptidases widely used in washing detergents. Its ability to cause respiratory allergy has been known. Up to now, most cases of occupational asthma (OA) to savinase have been described among workers involved in the manufacture of laundry detergents. We present a case study of 51-year-old female worker of a dishwashing tablets factory, who had been packaging ready-made tablets into foil wrappers for 4 years and developed respiratory symptoms, such as cough, dyspnoea and wheezing. Methods: A number of clinical procedures were performed, including the clinical examination, routine laboratory tests, evaluation of total and allergen-specific serum IgE (asIgE) to enzymes, skin prick tests for common allergens, rest spirometry, inhalation methacholine challenge test and a single-blind, placebo-controlled specific inhalation challenge test (SICT) with dishwashing tablets. Results: Clinical findings and results of routine laboratory tests were within normal limits. Baseline nonspecific bronchial hyperreactivity was revealed. In patient's serum blood we found significantly elevated asIgE to savinase. Decline of FEV1 and PEF in late phase of asthmatic reaction was observed during the specific challenge test. The patient reported chest tightness between 5-12 hours after exposure to dishwashing tablet ingredients. Cytological assessment of an induced sputum revealed increase in the percentage of eosinophils 24 hours after specific challenge in comparison to values noted before the SICT. Conclusions: Positive clinical response to the challenge confirmed in objective method tests validated the diagnosis of OA.(J Occup Health 2013; 55: 318-321)
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