Manual rolling load and low back pain among workers in Japan: a cross-sectional study.

OBJECTIVES: Manual rolling of heavy objects remains in the workplace. The Health and Safety Executive (HSE) in the United Kingdom recommends load weights of <400 kg in the rolling task. However, the association of rolling weights <400 kg with work-related low back pain (LBP) has not been sufficiently investigated. This study examined the effect of rolling loads weighing <400 kg on LBP among Japanese workers. METHODS: A web-based survey gathered information from 15 158 workers in 2022. Among them, 15 035 did not handle loads, whereas 123 handled rolling weights <400 kg. Load weight was categorized into 4 groups: no-handling (0 kg) and rolling weights of ≤20, 20-40, and >40 kg. Multiple logistic regression analysis examined the association between the subdivided rolling weight and LBP. RESULTS: No significant differences in odds ratio (OR) of LBP were found for workers handling ≤40 kg rolling weights compared with that for no-handling workers. However, workers handling >40 kg rolling weights had a significantly greater OR of LBP than those not handling loads. CONCLUSIONS: Rolling weights between 40 and 400 kg could place a high stress on the lower back. Implementation in Japan of the HSE recommendations regarding rolling load should be carefully considered.

Effect of occupational pushing and pulling combined with improper working posture on low back pain among workers.

This study aimed to investigate the impact of occupational pushing and pulling combined with improper working posture on work-related low back pain (LBP) among workers. A web-based survey was conducted in 2022 to collect data from 15,623 workers, who were categorized into proper and improper working posture groups. Multiple logistic regression analysis was used to analyze the association between pushing and pulling loads and LBP in each group. In the proper working posture group, the odds ratios (ORs) of LBP for workers who pushed and pulled were not significantly different compared with those of no-handling workers. However, in the improper working posture group, the ORs of LBP were significantly greater among workers who pushed and pulled compared with those of no-handling workers, and this association became stronger with increasing weights. Therefore, improper working posture combined with pushing and pulling were strongly associated with LBP among workers, particularly with heavier weights.

Effect of relative weight limit set as a body weight percentage on work-related low back pain among workers.

INTRODUCTION: A quarter of work-related low back pain (LBP) cases result from handling heavy loads in Japan. The maximum weight male/female workers can handle is 40%/24% of their body weight but has set a constant load weight in ISO 11228-1 and NIOSH lifting equation. The preventive effect of the relative weight limit on LBP has not been clarified. This study aimed to identify the effect of relative weight limits set as body weight percentages on LBP prevalence. METHODS: Data from 21924 workers were collected via a web-based survey in 2022. The workers were categorized into three groups: group A, "no handling," group B, "handling loads up to 40%/24% or less of body weight," and group C, "handling loads over 40%/24% of body weight." Moreover, they were categorized into eight groups: no handling, 1-5 kg, 5-10 kg, 10-15 kg, 15-20 kg, 20-25 kg, 25-30 kg, and ≥30 kg. Multiple logistic regression analysis was used to identify the effects of the limits set to body weight percentages and constant load weights on LBP. RESULTS: In groups A, B, and C, 25.5%, 39.2%, and 47.3% of males or 16.9%, 26.4%, and 38.0% of females had LBP, respectively. The odds ratio (OR) of LBP was significantly greater in group B than in group A and even greater in group C. The OR of LBP among workers handling loads under 10 kg was not significantly different compared to no-handling workers. CONCLUSIONS: LBP prevalence was greater in group B than in group A but lesser than in group C. Weight limits based on body weight percentages could not eliminate the factor of handling loads. However, handling loads under 10 kg suppressed LBP. Relative weight limits set as body weight percentages were inappropriate and ineffective for preventing LBP.

[Occupational low back pain in reports of workers' casualties between 2018 and 2019].

OBJECTIVES: Reports of workers' casualties include occupational low back pain (LBP), accounting for approximately 60% of compensable occupational disease. While LBP has become an important safety and health problem, the occurrence of occupational LBP has not been analyzed recently. This study aimed to evaluate the occurrence of occupational LBP in reports of workers' casualties between 2018 and 2019. METHODS: The study included 10,208 cases of occupational LBP (2018, n = 5,043; 2019, n = 5,165). Data on the location and date of industrial accidents, as well as type and size of business, age, sex, and leave period of the victims were tabulated. RESULTS: The number of occupational LBP cases was the highest in the health and hygiene industry (31.3%), followed by the commercial, manufacturing, and transportation industries. In the health and hygiene industry, social welfare facilities were listed in 24.3% of the total cases, and many caregivers suffered from LBP. Occupational LBP cases were less in cold regions and few during the cold period between November and January. Several occupational LBP cases occurred on Mondays following a holiday, and approximately 40% occurred between 9 a.m. and 12 a.m. Occupational LBP was frequently reported in workplaces with a volume of 10-49 workers, such as social welfare facilities in terms of business type. In terms of work-related accident victims per 100,000 workers, women were slightly more prone to LBP than men, and most of them were in their 20s and 30s. Approximately 60% of the leave period taken by victims was 2 weeks maximum. CONCLUSIONS: Occupational LBP was experienced by most workers in workplaces with at least 10-49 workers, such as social welfare facilities, between 2018 and 2019. In addition, LBP was more common in women than in men. Most workers with LBP take a leave period of 2 weeks. Suitable measures should be taken to prevent occurrences of occupational LBP.

Work e-mail after hours and off-job duration and their association with psychological detachment, actigraphic sleep, and saliva cortisol: A 1-month observational study for information technology employees.

OBJECTIVE: A sufficient duration of time off after work is necessary to ensure workers' health. Better quality of off-job time can also facilitate recovery from fatigue, but its quantitative influence is largely unknown. We aimed to examine how off-job time quality (as measured by the frequency of emailing after work), and off-job duration is associated with psychological detachment, actigraphic sleep, and saliva cortisol using a 1-month observational study. METHODS: The participants were 58 daytime employees working at an information technology company. Sleep actigraphy and saliva cortisol as well as self-reported outcomes were repeatedly measured for 1 month. Two-way (work e-mail frequency × off-job time) multilevel mixed-effects linear regression analyses were performed in both continuous and categorical variables. RESULTS: The frequency of work e-mailing after hours was significantly associated with self-reported outcomes and actigraphic sleep quality, while a significant association was not found in cortisol awakening responses and actigraphic sleep duration. A significantly larger cortisol response after awakening was found in shorter, rather than longer, durations of off-job time. Self-reported detachment, rumination and carry-over fatigue showed significant interactions between work e-mail and off-job time, suggesting that worse outcomes were found in a higher frequency of work e-mail even when employees had longer amounts of off-job time. CONCLUSION: Our findings suggest that ensuring the quality and duration of off-job time is beneficial for recovery from work with sufficient sleep. Specifically, the frequency of e-mailing after work should be minimized to make recovery complete.

Hair and fingernail cortisol and the onset of acute coronary syndrome in the middle-aged and elderly men.

Cortisol levels in hair and fingernail samples could represent hormone levels that have accumulated over the past weeks and months. In this study, by using retrospective indexes, the associations between cortisol and the onset of acute coronary syndrome (ACS) were investigated among middle-aged and elderly men. We measured hair/fingernail cortisol levels in 73 ACS patients and 93 healthy controls; hair and fingernail samples for ACS patients were collected within a few weeks after the onset of ACS. The results indicated the patients exhibited significantly higher cortisol levels in their hair and fingernails compared with the healthy controls. In multivariate logistic regression analyses, adjusting for the traditional cardiovascular risk factors for ACS, high levels of hair or fingernail cortisol were associated with two- to three-fold increased risk of ACS, compared with low levels. We demonstrated that cortisol exposure over a relatively long period, assessed by hair and fingernail samples, was associated with the onset of ACS.

Day-to-day variations in daily rest periods between working days and recovery from fatigue among information technology workers: One-month observational study using a fatigue app.

BACKGROUND: The European Union's Working Time Directive stipulates recovery periods as "Eleven consecutive hour daily rest periods (DRPs) between working days." In Japan, adopting this regulation has been discussed. OBJECTIVE: To examine the association between weekday DRPs and recovery from fatigue by conducting a one-month observational study using a fatigue monitoring application (fatigue app) on a smart tablet. METHODS: Fifty-five daytime employees working at an information technology company participated in this study. Visual analogue scales (VAS) regarding fatigue, psychological detachment from work, a psychomotor vigilance task (PVT), and sleep-wake logs were repeatedly measured using a fatigue app that we developed for this study. Sleep was measured by a wrist actigraph. RESULTS: The average and SD of weekday DRPs was 13.1 ± 2.3 h. However, 54.5% of employees experienced less than the minimum 11-hour DRP at least once a month. Sleep duration was significantly changed with weekday DRPs, though no significant difference was found in sleep efficiency. Linear mixed effects models showed that sleep duration increased by approximately 15 minutes for each hour of weekday DRPs (ß = 0.24, 95% CI; 0.17, 0.32, p <.001). VAS-measured fatigue and psychological detachment from work significantly improved as DRPs increased (ß = -3.4, 95% CI; -4.7, -2.1, p <.001; ß = 2.6, 95% CI; 1.2, 4.0, p <.001, respectively). However, PVT performance did not significantly change with weekday DRPs. CONCLUSIONS: Ensuring weekday DRPs plays an essential role in protecting the opportunities to sleep, with better recovery from fatigue and stress among information technology workers.

Psychosocial correlates of cortisol levels in fingernails among middle-aged workers.

It was recently suggested that cortisol levels in fingernails reflect cumulative hormone exposure over a relatively long period. This exploratory study cross-sectionally investigated the relationships between fingernail cortisol level and psychosocial stress in a sample of middle-aged workers (94 men and 29 women). The participants were asked to grow their fingernails for ∼2 weeks and then provide fingernail samples from every digit by using nail clippers. Further, they completed questionnaires for assessment of exposure to psychosocial stress in the past (stressful life events in the workplace in the previous year; e.g. change to a different line of work) and in the present (job stress and perceived stress). Results of a regression analysis adjusting for the effects of demographic variables showed that experience of stressful life events, but not job stress and perceived stress, was associated with elevated fingernail cortisol level. These findings indicate the potential of fingernail samples to retrospectively reflect individual differences in cortisol levels related to past psychosocial stress.

Cross-sectional associations between daily rest periods during weekdays and psychological distress, non-restorative sleep, fatigue, and work performance among information technology workers.

A daily rest period (DRP; rest taken from daily work during a 24 h period), is essential to work recovery. This study examined DRPs' distribution and association with health outcomes among information technology workers recruited from an internet panel (N=1,811). Participants completed a web questionnaire examining psychological distress as a primary outcome, along with non-restorative sleep, fatigue (stress reaction), and work performance. Logistic regression analysis showed elevated psychological distress when DRP was <12 h (OR: 2.54; 95% CI: 1.47-4.42) and <11 h (OR: 2.48, 95% CI: 1.17-5.26), although the 95% CI included 1 after adjusting for age, sex, and working and commuting hours. After the above adjustment, similar associations were found with non-restorative sleep and fatigue, but not work performance, when DRP was <12 h. These findings constitute the first analysis of a dose-response relationship between DRP and subjective health outcomes among white-collar workers.

Cortisol level measurements in fingernails as a retrospective index of hormone production.

The cortisol level in fingernails may reflect the hormone's cumulative production over a long period, but the notions have not been fully established. In this study, we investigated the association of cortisol in fingernails with cortisol accumulation over a long period (hair cortisol) and over a relatively short period (salivary cortisol). In study 1, hair and fingernail samples were collected from 58 middle-aged and elderly men. The cortisol level in hair samples was moderately associated with the level in fingernail samples (r = 0.29, p < 0.05 and rs = 0.36, p < 0.01). In study 2, 37 workers provided 4 saliva samples over the course of one day (at awakening, 30 min after awakening, before lunch, and after work) and another set a month later. Further, the workers were asked to provide fingernail samples during a six-month period. We found that the cortisol level in saliva over the whole day (area under the curve for cortisol) was moderately associated with the cortisol level measured in fingernail samples that were collected 4 months (r = 0.43, p < 0.05 and rs = 0.50, p < 0.01) and 5 months later (r = 0.45, p < 0.05 and rs = 0.53, p < 0.01). These results indicated that the cortisol level in fingernail samples might retrospectively represent hormone production during a given period. The cortisol level in fingernail samples may be useful in the investigation of the link between psychosocial stress and health.

The diurnal patterns of salivary interleukin-6 and C-reactive protein in healthy young adults.

In recent years, salivary inflammatory markers, such as interleukin-6 (IL-6) and C-reactive protein (CRP), have been investigated regarding their relationships with psychosocial stress and stress-related diseases. This study investigated the diurnal patterns of salivary IL-6 and CRP in healthy young adults. Twenty-seven students (11 males and 16 females) participated in this study. The participants were instructed to provide saliva samples 8 times a day (at 0700, 0730, 1000, 1300, 1600, 1900, 2200, and 0100 h). For the duration of study, they were asked to wake up at 0700 h and go to bed after 0100 h. Twelve of the participants were asked to repeat this sampling procedure on two consecutive days to test the stability of the diurnal patterns. The salivary IL-6 levels peaked at awakening, gradually declined from morning to noon, and peaked again at midnight, before the participants went to sleep. The salivary CRP levels peaked at awakening, and they were lower during the daytime. The salivary IL-6 and CRP levels exhibited moderate to high stability over 2 days of sample collection. This study revealed that the salivary inflammatory markers had distinctive diurnal patterns.