[Occupational cancer].

Occupational cancer is one of the most important topics in occupational health, because it can be avoided by using appropriate risk management strategies at work. However, due to the lack of suitable surveillance systems in Japan, it goes under-recognized. Burden of disease studies conducted elsewhere can be extrapolated to suggest thousands of deaths are attributable to occupational cancer in Japan. By law, about 20 kinds of cancer have been listed as occupational hazards; among those is asbestos related cancer. In fact, in recent years, thousands of asbestos related cancer cases have been compensated by the government run workers' compensation scheme for occupational accidents and diseases. On the other hand, for the other types of occupational cancer, only few cases are reported. To prevent re-emergence of occupational cancer, such as the recently publicized cholangiocarcinoma epidemics, employees, employers, medical institutions and competent authorities are strongly urged to establish better surveillance systems for occupational cancer.

Ergonomics observation: Harvesting tasks at oil palm plantation.

OBJECTIVES: Production agriculture is commonly associated with high prevalence of ergonomic injuries, particularly during intensive manual labor and during harvesting. This paper intends to briefly describe an overview of oil palm plantation management highlighting the ergonomics problem each of the breakdown task analysis. METHODS: Although cross-sectional field visits were conducted in the current study, insight into past and present occupational safety and health concerns particularly regarding the ergonomics of oil palm plantations was further exploited. Besides discussion, video recordings were extensively used for ergonomics analysis. RESULTS: The unique commodity of oil palm plantations presents significantly different ergonomics risk factors for fresh fruit bunch (FFB) cutters during different stages of harvesting. Although the ergonomics risk factors remain the same for FFB collectors, the intensity of manual lifting increases significantly with the age of the oil palm trees-weight of FFB. CONCLUSIONS: There is urgent need to establish surveillance in order to determine the current prevalence of ergonomic injuries. Thereafter, ergonomics interventions that are holistic and comprehensive should be conducted and evaluated for their efficacy using approaches that are integrated, participatory and cost-effective.

The prevalence of musculoskeletal disorder and association with productivity loss: a preliminary study among labour intensive manual harvesting activities in oil palm plantation.

Production agriculture such as harvesting in oil palm plantation has been frequently associated with MSD and significant loss of productivities. This study tends to evaluate from the viewpoint of health, the association between self-reported prevalence of musculoskeletal disorders and productivities; the impact of musculoskeletal disorders on productivity. A cross-sectional study was conducted among 143 harvesters in oil palm plantation. A general questionnaire was used to collect socio-demographic background data while Nordic Musculoskeletal Questionnaire was used to determine the prevalence of MSD. Expressed in 4 different indicators; daily harvesting quantity, efficiency score, sick leave and presenteeism, the productivity data were analysed for association. There is significant association between reported acute prevalence of MSD (within 7 d) and productivity loss in terms of presenteeism (χ(2)=5.088; p<0.05) as well as quantity of daily harvest (χ(2)=7.406; p<0.01). Logistic regression adjusted for age, BMI and smoking indicate that harvesters with MSD (past seven days) were more likely to be engaged in presenteeism (OR=2.87 95% CI=1.34, 6.14) and had lower daily productivity (OR=2.09 95% CI=1.02, 4.29) compared to harvesters without MSD (past 7 d). This study reveals that oil palm harvesters suffering acute MSD (for the past week) were likely to be still present to work and produce half lesser than their healthy counterparts. Thus, further study with comprehensive surveillance strategy is essential in order to determine the urgency or need of appropriate intervention.

Sleep, fatigue, recovery, and depression after change in work time control: a one-year follow-up study.

OBJECTIVE: We examined how change in work time control was associated with sleep and health 1 year later. METHODS: Work time control, sleep, fatigue, recovery, and depression were assessed at baseline (T1) and at follow-up (T2) for 2382 daytime workers. The change in work time control from T1 to T2 was classified into four groups: low to low, low to high, high to low, and high to high. RESULTS: A repeated-measures analysis of covariance showed significant decreases in the frequency of insomnia symptoms and depressive symptoms from T1 to T2 for the low to high group, which were similar to the high to high group. Significantly lower fatigue was found for these two groups at T2. CONCLUSION: An increase in work time control, in addition to its stable high level, may produce beneficial effects upon sleep and health.

Seasonal and inter-day variation in serum high-sensitivity C-reactive protein in Japanese male workers: a longitudinal study.

Although seasonal variation in high-sensitivity C-reactive protein (hsCRP) has been studied cross-sectionally and longitudinally, the results to date have been mixed. Here, to test seasonal variation in this compound with regard to within-subject, inter-day variation, we conducted a longitudinal follow-up study with repeated measurements in Japanese workers with low hsCRP. Blood samples were obtained from four male indoor daytime workers, who were aged 32-57 and commuted to offices in Kawasaki City, on six days within 2-wk windows in February and October, 2008. Serum hsCRP was measured using ultrasensitive latex-enhanced immunonephelometry. Among the subjects with detectable levels of hsCRP, individual median serum hsCRP levels were 38-74% higher in October than in February (p=0.03). This study identified the presence of a seasonal variation in the serum hsCRP level of Japanese workers with low hsCRP levels.

Vitamin D deficiency and seasonal and inter-day variation in circulating 25-hydroxyvitamin D and parathyroid hormone levels in indoor daytime workers: a longitudinal study.

Seasonal variation in circulating 25-hydroxyvitamin D (25OHD) levels related to seasonal and inter-day fluctuation in sunlight ultraviolet irradiation, may lead to misjudgments concerning 25OHD status in individual workers around threshold levels. Here, to examine seasonal and inter-day variations in plasma 25OHD, we conducted a longitudinal study involving indoor daytime workers. Subjects were four male indoor daytime workers aged 32-57 yr working in Kawasaki City, Japan. Blood samples were obtained on six days within two two-week periods in February and October, 2008. Plasma 25OHD, serum intact parathyroid hormone (PTH) and 1α,25-dihydroxyvitamin D [1α,25(OH)(2)D] were measured. Individual monthly mean 25OHD levels were 16-56% higher in October than in February (p=0.03), while individual monthly mean intact PTH levels were 15-41% lower in October (p=0.09). No seasonal change was observed in 1α,25(OH)(2)D (p=0.62). Notably, nearly all measured 25OHD levels in February were lower than the reference value of 20 ng/ml. Our study identified the occurrence of seasonal variation in circulating 25OHD and intact PTH levels, even after accounting for inter-day variability, and hypovitaminosis D in wintertime in indoor daytime male workers in Japan. Due to this variability, single spot measurements of 25OHD may lead to misjudgment of workers' vitamin D status.

Worktime control-dependent reductions in fatigue, sleep problems, and depression.

We investigated the association between worktime control and fatigue, sleep problems, and depressive symptoms in a sample of daytime and shift workers. A total of 3681 permanent daytime workers and 599 shift workers completed a questionnaire designed to assess the above variables. Worktime control was evaluated in terms of both "control over daily working hours" and "control over days off". Worktime control × work schedule × gender analysis of covariance, adjusted for age and employment status, showed overall reductions in incomplete recovery, insomnia symptoms, daytime sleepiness, and depressive symptoms with increasing levels of worktime control. However, no associations between control over daily working hours and insomnia symptoms were observed in women. The reductions appeared to be more evident for control over days off. These results remained consistent after adjustments for other potential covariates. The present findings indicate that increased worktime control and enhanced control over days off in particular, may be associated with favorable health outcomes.

A nation-wide survey on indoor radon from 2007 to 2010 in Japan.

In two previous nation-wide surveys in the late 1980s and early 1990s, Japanese indoor radon concentrations increased in homes built after the mid 1970s. In order to ascertain whether this trend continued, a nation-wide survey was conducted from 2007 to 2010. In total 3,900 houses were allocated to 47 prefectures by the Neyman allocation method and 3,461 radon measurements were performed (88.7% success). The fraction of reinforced concrete / concrete block buildings was 32.4%, similar to the value from national statistics. Arithmetic mean (standard deviation, SD) and geometric mean (geometric SD) of radon concentration after adjusting for seasonal fluctuation were 14.3 (14.7) and 10.8 (2.1) Bq/m(3). The corresponding population-weighted values were 13.7 (12.3) and 10.4 (2.0) Bq/m(3), respectively. It was estimated that only 0.1% of dwellings exceed 100 Bq/m(3), a new WHO reference level for indoor radon. Radon concentrations were highest in houses constructed in the mid 1980s and decreased thereafter. In conclusion, arithmetic mean indoor radon in the present survey was slightly lower than in previous surveys and significant reductions in indoor radon concentrations in both wooden and concrete houses can be attributed to alterations in Japanese housing styles in recent decades.

Working hours, coping skills, and psychological health in Japanese daytime workers.

This study examined the relationship between coping skills, working hours, and psychological health among Japanese daytime workers. Self-administered questionnaires were mailed to a randomly selected sample of 2,000 workers who were members of a pre-recruited market research panel. A total of 1,821 participants responded (response rate=91.1%). Participants completed a questionnaire regarding working hours, coping skills, and psychological health (negative emotions, fatigue, and concentration/activity levels). Analyses of covariance were conducted to determine the relations of number of working hours, coping skills, and their interactions to psychological health with control for sex, age, drinking, job type, and employment type. Results revealed that working hours were significantly associated with fatigue and concentration/activity levels. High levels of instrumental support and positive reframing were significantly associated with low levels of negative emotions, fatigue, and concentration/activity levels. High levels of self-blame, denial, substance use, venting, self-distraction, religion, and behavioral disengagement were significantly associated with high levels of negative emotions, fatigue, and concentration/activity levels. This study suggests that improving coping skills such as using instrumental support or positive reframing may reduce the adverse health effects of long working hours.

Does leaning posture on the kitchen counter alleviate workload on the low back and legs during dishwashing?

In this study, we evaluated the effects of leaning posture on the kitchen counter, which was observed during dishwashing in a kitchen, on subjective discomfort and muscle activity in the low back and legs. Twelve female volunteers were asked to wash plates for 30 min in each of three working postures: (a) without support (No support), (b) supported by the kitchen counter (Counter), and (c) supported by a standing aid which was a stand equipment to support the shins and the counter (Aid and counter). In the "Aid and counter" posture, the angle of the bent trunk and the muscle activity in the low back were less than that in the "Counter" posture, which was less than that in the "No support" posture. Also, the muscle activities in the legs were greater in the "Counter" and "No support" postures than in the "Aid and counter" posture. We concluded that the effects of leaning posture on the kitchen counter were not enough to decrease the workload on the low back and legs. To improve the comfort of the dishwashing task, new measures, such as the standing aid, are needed.

Overtime, job stressors, sleep/rest, and fatigue of Japanese workers in a company.

To ascertain the usefulness of a 21-item checklist that assesses accumulated fatigue due to overwork, we examined (1) the associations between overtime work, job stressors, or the quantity of sleep/rest and subjective symptoms of fatigue, and (2) whether sleeping hours and monthly days off are associated with the accumulated fatigue parameter using the checklist. Questionnaire surveys were administered twice to Japanese workers at a plant of a manufacturing company. Among the 390 registered workers, 383 workers (284 males and 99 females) in the first survey and 350 workers (260 males and 90 females) in the second survey responded. The subjective symptoms score significantly increased according to the order of grade of overtime work, other job stressors, and sleep/rest subscales in both sexes by ANOVA. The subjective symptoms grade was significantly associated with the other job stressors grade and sleep/rest grade, but not with overtime work. The accumulated fatigue parameter was negatively correlated with daily sleeping hours (significant Spearman's correlation coefficient (r(s)) =-0.318 and -0.340 in the 1st and 2nd surveys) and with monthly days off (r(s)=-0.250 and -0.151) among all of the subjects. It may be possible to assess overwork by the accumulated fatigue parameter.

Inverse relationship between serum erythropoietin and blood lead concentrations in Kathmandu tricycle taxi drivers.

OBJECTIVE: Kathmandu tricycle taxi drivers, whose environmental lead (Pb) exposure is ascribable mainly to vehicular exhaust, were studied to examine a dose-response relationship between blood Pb (Pb-B) and serum erythropoietin (sEPO) concentrations. METHODS: Subjects were 27 drivers and 9 non-drivers. They were non-anemic healthy men with normal renal function. Pb-B was measured by an atomic absorption spectrometer with a graphite furnace, and sEPO was determined with a sandwich-type enzyme-linked immunosorbent assay. RESULTS: sEPO levels in drivers were lower than those of non-drivers, while Pb-B levels in drivers were higher than those of non-drivers. There was an inverse relationship between Pb-B and sEPO. CONCLUSIONS: The data suggest that Pb inhibits renal EPO production in a dose-dependent manner in persons with subclinical Pb toxicity. sEPO may serve as an early biochemical marker of subclinical Pb toxicity.

Relationship between blood lead level and work related factors using the NIIH questionnaire system.

Over an 11-yr period (1990-2000), a questionnaire survey on work environmental management and environmental improvement was conducted on 259 lead-handling factories and 7,623 subjects. Labour Inspection Offices identified these factories as requiring environmental improvement, or possessing a desire to improve their working environment. We analyzed factors affecting blood lead levels (PbBs). These factors were gender, age, employment duration, factory size, work environment control (WEC) class, and job categories. The PbB of men was found to be higher than that of women, and may be due to the differences in job distribution. PbB increased along with increasing age and employment duration. PbB declined as the factory size increased. The odds ratio (OR) of PbB higher than 20 microg/dl according to factory size was significantly high even after adjusting for WEC class. This demonstrates that not only the working environment but also safety management was poorer among small-scale factories that large-scale factories. The rise of PbB along with the increase of WEC class confirmed that the results of work environment measurement are correlated with individual exposure levels. The risk of having a 20 microg/dl or higher PbB was different for various lead handling jobs. Smelting or refining lead had the highest risk for lead exposure while painting or baking had the lowest risk. As our study population was not a randomly selected sample, we are unable to generalize our results for workers across Japan. However, we were able to indicate which jobs pose a high-risk and the effectiveness of using the work environment control class as an index of worksite environment levels.

[VDT worker's posture and workload in free-address office system].

A free-address system is a new office layout in which a worker can freely sit in their favorite place with a computer and materials. Since this layout has recently been introduced in offices, we conducted a questionnaire survey which aimed to clarify the effects of the free-address system on visual display terminals (VDT) workers' posture and workload. A total of 203 male VDT workers who were system engineers aged 20 to 59 using a notebook computer were evaluated, of whom 150 used the free-address layout, and 53 used the fixed-address layout. The free-address layout was effective in the improvement of individual work space compared with the fixed-address layout. Also, in this layout the worker did not feel dissatisfaction with communication or support between workers. However, workers using the free-address layout assumed an unsuitable work posture, without adjusting the height of their chairs. Furthermore, this layout might have risk factors which increase neck/shoulder and low back stiffness and/or pain. Therefore, the free-address layout may have incipient problems, and it will be necessary to examine further the effects of this layout on VDT worker's health.

Development of rice husks-plastics composites for building materials.

In this paper, a new effective recycling method for rice husks and waste expanded polystyrene is developed by using a combination of both wastes. A styrene solution of waste expanded polystyrene is used as a binder for rice husks-plastics composites. The composites are prepared with various mix proportions by a hot press molding method, and tested for apparent density, water absorption, expansion in thickness, and dry and wet flexural strengths. From the test results, the apparent density of the composites is increased with increasing binder content and filler-binder ratio. Their flexural strength and wet flexural strengths reach maximums at a binder content of 30.0% and a filler-binder ratio of 1.0. Their water absorption and expansion in thickness are decreased with increasing binder content and filler-binder ratio. Since the composites have a high flexural strength and water resistance, their uses as building materials are expected.

Development of action checkpoints for comfortable computer work.

We developed a manual including a checklist format for undertaking measures to prevent fatigue in visual display terminals (VDT) workers. With this manual, problems related to VDT work can be recognized by using checklists which allow for self-evaluation by the workers. The manual helps the workers to consider measures for improvement by themselves and will contribute to better occupational health education.

Shape and thickness of cushion in a standing aid to support a forward bending posture: effects on posture, muscle activities and subjective discomfort.

In order to prevent low back pain (LBP) during dishwashing, we developed three types of aid with a thick cushion for supporting the shins and evaluated the effects of the standing aid on the subjective discomfort and muscle activities. Nine female volunteers were asked to wash plates in each of four working postures: (a) without the standing aid, (b) with the round type of aid, (c) with the small rectangular type of aid, and (d) with the large rectangular type of aid. With the three types of aid, the subjects were instructed to support the shins with the standing aid and to support the abdomen with the edge of a kitchen counter. In the three postures with the standing aid, 21.5 +/- 10.0% of the weight was supported with the standing aid and the kitchen counter. The subjective discomfort was milder and the muscle activity level in the low back was lower in the three postures with the standing aid than in the posture without the aid. It was thought that the round type of aid would be more effective in decreasing the discomfort in many of body regions and the muscle load on the low back than either of the rectangular types of aid. Therefore, it was suggested that the standing aid had the desired effect in decreasing discomfort and muscle load on the low back during dishwashing.