Journal of Occupational Health
Online ISSN : 1348-9585
Print ISSN : 1341-9145
Volume 58 , Issue 6
Showing 1-14 articles out of 14 articles from the selected issue
Originals
  • Yoshiko Kubo, Yoko Hatono, Tomohide Kubo, Satoko Shimamoto, Junko Naka ...
    2016 Volume 58 Issue 6 Pages 519-533
    Published: November 20, 2016
    Released: November 29, 2016
    [Advance publication] Released: September 30, 2016
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    Objectives: This study aimed to develop the Career Anchors Scale among Occupational Health Nurses (CASOHN) and evaluate its reliability and validity. Methods: Scale items were developed through a qualitative inductive analysis of interview data, and items were revised following an examination of content validity by experts and occupational health nurses (OHNs), resulting in a provisional scale of 41 items. A total of 745 OHNs (response rate 45.2%) affiliated with the Japan Society for Occupational Health participated in the self-administered questionnaire survey. Results: Two items were deleted based on item-total correlations. Factor analysis was then conducted on the remaining 39 items to examine construct validity. An exploratory factor analysis with a main factor method and promax rotation resulted in the extraction of six factors. The variance contribution ratios of the six factors were 37.45, 7.01, 5.86, 4.95, 4.16, and 3.19%. The cumulative contribution ratio was 62.62%. The factors were named as follows: Demonstrating expertise and considering position in work (Factor 1); Management skills for effective work (Factor 2); Supporting health improvement in groups and organizations (Factor 3); Providing employee-focused support (Factor 4); Collaborating with occupational health team members and personnel (Factor 5); and Compatibility of work and private life (Factor 6). The confidence coefficient determined by the split-half method was 0.85. Cronbach's alpha coefficient for the overall scale was 0.95, whereas those of the six subscales were 0.88, 0.90, 0.91, 0.80, 0.85, and 0.79, respectively. Conclusions: CASOHN was found to be valid and reliable for measuring career anchors among OHNs in Japan.

  • Chadayu Udom, Prawit Janwantanakul, Rotsalai Kanlayanaphotporn
    2016 Volume 58 Issue 6 Pages 534-542
    Published: November 20, 2016
    Released: November 29, 2016
    [Advance publication] Released: September 30, 2016
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    Objectives: Low back pain (LBP) is one of the most prevalent musculoskeletal disorders in the general population, especially among manual laborers. Moreover, it often brings about lost wages and additional medical expenses. However, the potential risk factors for LBP are unknown. This study aimed to estimate the prevalence of LBP and to determine the individual, occupational, and psychosocial factors associated with LBP among rubber farmers. Methods: A cross-sectional survey was conducted among 450 Thai rubber farmers using cluster random sampling. Data were collected using face-to-face interviews and objective examination and were analyzed using multivariate logistic regression. Results: Of the 433 rubber farmers, the point and 12-month prevalence of LBP in rubber farmers was 33% and 55.7%, respectively. BMI, primary school education, exposure to pesticides, and tapping below knee level were statistically associated with LBP after controlling for other variables. Conclusions: Low back pain is common among rubber farmers. Only four factors were identified as being associated with the high prevalence of LBP. However, these factors might be altered if more variables are taken into account. Further research investigating the causal relation between these factors and LBP should be conducted.

  • Ayako Hino, Akiomi Inoue, Kosuke Mafune, Toru Nakagawa, Takeshi Hayash ...
    2016 Volume 58 Issue 6 Pages 543-562
    Published: November 20, 2016
    Released: November 29, 2016
    [Advance publication] Released: September 30, 2016
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    Objective: This study investigated the impact of changes in psychosocial work characteristics on insulin resistance (IR) among Japanese male workers. Methods: Subjects were 1,815 male workers who received a comprehensive health examination and requested measurement of their serum insulin level in Fiscal Years (FY) 2008 and 2011. Psychosocial work characteristics, including job demands, job control, and workplace social support (from supervisors and coworkers), were assessed in each of the job demands-control and demand-control-support models. Psychosocial work characteristics were assessed by the Brief Job Stress Questionnaire. Changes in the psychosocial work characteristics were measured by creating a four-category variable for each of the psychosocial work characteristics: (1) stable low group, (2) increased group, (3) decreased group, and (4) stable high group. We defined IR as a value of 2.5 or more on the homeostasis model assessment of insulin resistance (HOMA-IR), or having a diagnosis of diabetes. A series of multiple logistic regression analyses were conducted. Results: The group experiencing a decrease in supervisor support had a significantly higher risk of having IR compared to the stable high group with an odds ratio (OR) of 2.44; 95% CI: 1.48-4.02. After adjusting for covariates, this significant association was unchanged; the OR was 2.19; 95% CI: 1.23-3.91. On the other hand, there was no significant association of changes in the psychosocial work characteristics, expect for decrease in supervisor support, with IR. Conclusions: A decrease in supervisor support was found to be an independent risk factor for worsening IR.

  • Rajesha K Nairy, Narayana Yerol, Nagesh N Bhat, Utkarsha Desai, Kapil ...
    2016 Volume 58 Issue 6 Pages 563-569
    Published: November 20, 2016
    Released: November 29, 2016
    [Advance publication] Released: October 07, 2016
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    Objective: In the present study an attempt was made to estimate coefficients of dose response curves for PCC aberrations induced by CalyculinA and Okadaic acid, using 60Co gamma radiation and 8 MeV pulsed electron beam for biodosimetry application. Materials and Methods: The modified method outlined by Puig et al. 2013 was used to conduct Calyculin A and Okadaic acid induced PCC assay in human blood lymphocytes.Chemical treatment was given for the last 1 h of a 48 h culture. The study was carried out in the dose range 2.5 to 20 Gy using 60Co gamma rays and 8 MeV pulsed electron beam. Results and Conclusions: Results show a linear dose dependent increase with a slope of 0.047 ± 0.001 from Calycalin A PCC and 0.048 ± 0.002 form Okadaic acid PCC. The slope of the fragments curve was 0.327 ± 0.006 from Calyculin A and 0.328 ± 0.006 from Okadaic acid PCC. Further, dose calibration studies were carried out for 8 MeV electron using Calyculin A PCC assay and the obtained slope from ring yield was 0.054 ± 0.002 and 0.427 ± 0.009 from fragment yield.

  • Hironobu Abiko, Mitsuya Furuse, Tsuguo Takano
    2016 Volume 58 Issue 6 Pages 570-581
    Published: November 20, 2016
    Released: November 29, 2016
    [Advance publication] Released: September 30, 2016
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    Objectives: In the use of activated carbon beds as adsorbents for various types of organic vapor in respirator gas filters, water adsorption of the bed and test gas humidity are expected to alter the accuracy in the estimation of breakthrough data. There is increasing interest in the effects of moisture on estimation methods, and this study has investigated the effects with actual breakthrough data. Methods: We prepared several activated carbon beds preconditioned by equilibration with moisture at different relative humidities (RH=40%-70%) and a constant temperature of 20°C. Then, we measured breakthrough curves in the early region of breakthrough time for 10 types of organic vapor, and investigated the effects of moisture on estimation using the Wheeler-Jonas equation, the simulation software NIOSH MultiVapor™ 2.2.3, and RBT (Relative Breakthrough Time) proposed by Tanaka et al. Results: The Wheeler-Jonas equation showed good accordance with breakthrough curves at all RH in this study. However, the correlation coefficient decreased gradually with increasing RH regardless of type of organic vapor. Estimation of breakthrough time by MultiVapor showed good accordance with experimental data at RH=50%. In contrast, it showed discordance at high RH (>50%). RBTs reported previously were consistent with experimental data at RH=50%. On the other hand, the values of RBT changed markedly with increasing RH. Conclusions: The results of each estimation method showed good accordance with experimental data under comparatively dry conditions (RH≤50%). However, there were discrepancies under high humidified conditions, and further studies are warranted.

  • Wanhyung Lee, Kwanyoung Hong, Sung-Shil Lim, Jin-Ha Yoon
    2016 Volume 58 Issue 6 Pages 582-592
    Published: November 20, 2016
    Released: November 29, 2016
    [Advance publication] Released: September 30, 2016
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    Objectives: Many aging workers wish to continue working as long as they can for a better life in the future. However, symptoms of pain are a key obstacle in the continuation of work among older workers. The impact of pain on work is understudied. Thus, we investigated the relationship between pain characteristics (total site and severity) and aging workers' working life expectancy scale (WoLES) in Korea. Methods: We included 1,979 participants (1,175 men and 804 women) from a well-established survey of a nationally representative population: the Korean Longitudinal Study of Ageing. A self-questionnaire was used to assess pain characteristics and WoLES. Odds ratios (ORs) and 95% confidence intervals (CIs) for the lower-WoLES group were calculated using multiple logistic regression models. Results: Compared with the absence of pain, ORs and 95% CIs of the lower-WoLES group were increased, as follows: 1 pain site, 1.75 (1.20-2.55); 2 pain sites, 1.99 (1.32-3.03); 3 or more pain sites, 2.28 (1.51-3.42); mild pain, 1.74 (1.32-2.61); moderate pain, 2.02 (1.28-3.22); and severe pain, 2.12 (1.46-3.08). The statistical trend was significant in both total sites and severity of pain (p<0.001). Conclusions: There was a significant association between WoLES and both total pain sites and severity of pain, even after adjusting for potential confounding factors.

  • Tagayasu Tanaka, Ryoichi Inaba, Atsuhito Aoyama
    2016 Volume 58 Issue 6 Pages 593-601
    Published: November 20, 2016
    Released: November 29, 2016
    [Advance publication] Released: September 30, 2016
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    Objectives: This study investigated the actual situation of noise and low-frequency sounds in firework events and their impact on pyrotechnicians. Methods: Data on firework noise and low-frequency sounds were obtained at a point located approximately 100 m away from the launch site of a firework display held in "A" City in 2013. We obtained the data by continuously measuring and analyzing the equivalent continuous sound level (Leq) and the one-third octave band of the noise and low-frequency sounds emanating from the major firework detonations, and predicted sound levels at the original launch site. Results: Sound levels of 100-115 dB and low-frequency sounds of 100-125 dB were observed at night. The maximum and mean Leq values were 97 and 95 dB, respectively. The launching noise level predicted from the sounds (85 dB) at the noise measurement point was 133 dB. Occupational exposure to noise for pyrotechnicians at the remote operation point (located 20-30 m away from the launch site) was estimated to be below 100 dB. Conclusions: Pyrotechnicians are exposed to very loud noise (>100 dB) at the launch point. We believe that it is necessary to implement measures such as fixing earplugs or earmuffs, posting a warning at the workplace, and executing a remote launching operation to prevent hearing loss caused by occupational exposure of pyrotechnicians to noise. It is predicted that both sound levels and low-frequency sounds would be reduced by approximately 35 dB at the remote operation site.

  • Takami Okada, Akira Ogami, Byeong Woo Lee, Chikara Kadoya, Takako Oyab ...
    2016 Volume 58 Issue 6 Pages 602-611
    Published: November 20, 2016
    Released: November 29, 2016
    [Advance publication] Released: September 30, 2016
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    Objective: Titanium dioxide nanoparticles are widely used as UV filters in cosmetics and as a photocatalyst. We evaluated pulmonary responses to different crystal forms of TiO2 nanoparticles. Methods: We used 4 different TiO2 samples with similar specific surface areas (anatase, rutile, amorphous, and P25). Each sample was suspended in distilled water and intratracheally instilled to male Wister rats at the dose of 1 mg per rat. Five rats per group were sacrificed at 3 days, 1 month, and 6 months after instillation, and bronchoalveolar lavage fluid was collected from the right lung to determine the total cell count and polymorphonuclear cell (PMN) counts. The left lung tissues were stained with hematoxylin and eosin for the evaluation of inflammation and with elastica van Gieson for the evaluation of collagen deposition. Results: The total cell counts and PMN counts of the amorphous and P25 of four samples showed a significant increase compared with the control group at 3 days after instillation. The inflammation rate of P25 also showed a significant increase compared with controls at 3 days. The collagen deposition rate in the alveolar duct of P25 increased significantly compared with controls from 3 days to 6 months. The other samples showed a mild response after instillation. Conclusion: Although the TiO2 nanoparticles used in this study had similar specific surface areas, there were different inflammatory responses in the rat lungs. Other factors, such as different production processes or the surface activities of particles, may have been responsible for the different responses.

  • Tsukimi Tsukada, Hisataka Sakakibara
    2016 Volume 58 Issue 6 Pages 612-621
    Published: November 20, 2016
    Released: November 29, 2016
    [Advance publication] Released: September 30, 2016
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    Objectives: This study aimed to examine effective assessment methods of falls in the workplace. Methods: There were 436 employees (305 males and 131 females) of electrical appliance manufacturers included in this study. In 2014, a baseline survey was conducted using the fall scores questionnaire and the self-check risk assessment of falls and other accidents in the workplace (physical function measurement and questionnaire). In 2015, the occurrence of falls in the past year was investigated. Multivariate logistic regression analyses were performed to examine factors relevant to falls. Results: In total, 62 subjects (14.2%) fell during the year, including those who fell during off-hours. The occurrence of falls during that one year was only associated with having experienced falls during the past year in the baseline survey (odds ratio [OR] 5.0; 95% confidence interval [CI] 2.5-9.7). Falls during that year were also related to the inability to walk 1 km continuously (OR 0.1; 95% CI 0.1-0.6), tripping sometimes (OR 4.0; 95% CI 1.6-9.9), step height differences at home (OR 3.0; 95% CI 1.3-6.8), and working in the production section (OR 0.2; 95% CI 0.1-0.5). Measurements of physical functions, such as muscle strength, balance, and agility, were not different between subjects who fell and those who did not. Conclusions: Our results showed that the questionnaire assessing falls during the past year could be useful to assess the risk of falls in the workplace. Annual checks for falls may contribute to fall prevention programs in the workplace.

  • Toshiaki Sasaki, Masumi Asakura, Chigusa Ishioka, Tatsuya Kasai, Taku ...
    2016 Volume 58 Issue 6 Pages 622-631
    Published: November 20, 2016
    Released: November 29, 2016
    [Advance publication] Released: October 07, 2016
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    Objectives: IARC has classified one type of multi-walled carbon nanotubes (MWCNTs), MWNT-7, as possibly carcinogenic to humans (Group 2B); however, other types of MWCNT were categorized as not classifiable as to their carcinogenicity to humans (Group 3). In vitro chromosomal aberration assays of MWNT-7 showed polyploid formation but not structural abnormalities. This study investigated the influence of the shape and size of MWCNT on in vitro induction of chromosomal aberrations. Methods: Microscopic analysis and viable cell counting were used to assay for chromosomal aberrations and cytotoxicity induced in a Chinese hamster lung cell line (CHL/IU) exposed to different MWCNTs. Results: Using scanning electron microscopy, seven MWCNTs were classified into three types: straight fibrous, curved fibrous, and tangled. The straight fibrous MWCNTs were the strongest inducers of polyploidy and the most cytotoxic among the three types of MWCNTs. The curved fibrous MWCNTs induced more polyploidy than the tangled MWCNTs, and the cytotoxicity of both types seemed to be a reflection of their induction of polyploidy. None of the seven MWCNTs induced structural chromosomal aberrations. Conclusion: The non-clastogenicity of the MWCNTs indicates that the MWCNTs may not interact directly with DNA. Since the straight fibrous MWCNTs, which exhibit a structure similar to asbestos, were the strongest inducers of polyploidy, MWCNT shape may be an important factor in induction of polyploidy. We hypothesize that CHL/IU cells endocytosed MWCNTs and formed endosomes with shapes corresponding to those of the endocytosed MWCNTs, and that the long axis diameter of the endosome is important in the capability of MWCNTs to induce polyploidy.

  • Yumiko Maekawa, Juan Ramos-Cejudo, Atsuko Kanai
    2016 Volume 58 Issue 6 Pages 632-639
    Published: November 20, 2016
    Released: November 29, 2016
    [Advance publication] Released: October 07, 2016
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    Objectives: Although using mental health services is an effective way to cope with work-related stressors and diseases, many employees do not utilize these services despite service improvements in recent years. The present study aimed to investigate the interaction effects of workplace climate and distress on help-seeking attitudes, and elucidate the reasons for mental health service underutilization in Japan. Methods: A questionnaire was distributed to 650 full-time male Japanese employees. Hierarchical multiple regression analysis was used to investigate interaction effects of workplace climate and distress on help-seeking. Results: Results showed that the association between workplace climate and help-seeking attitudes differed depending on employee distress level. For employees experiencing low levels of distress, openness to seeking treatment increased with a higher evaluation of the mental health services available at the workplace. However, the same did not hold true for employees experiencing high levels of distress. Instead, openness to seeking treatment decreased with perceived risk for career disadvantage for high distress employees. Additionally, negative values for seeking treatment in highly distressed employees decreased only when services were perceived as valuable, and the risk to their career was perceived as low. Conclusions: Overall, these findings indicate that distress distorts the perception of social support, which may lead to underutilization of available services. Assessing employees' distress levels and tailoring adequate interventions could facilitate help-seeking in male employees.

Brief Report
  • Jun Ojima
    2016 Volume 58 Issue 6 Pages 640-643
    Published: November 20, 2016
    Released: November 29, 2016
    [Advance publication] Released: September 30, 2016
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    Objectives: The International Agency for Research on Cancer (IARC) and Japan Society for Occupational Health (JSOH) classified wood dust as a human carcinogen. Former studies have suggested that sanding with a portable sander is one of the processes that are liable to cause highest exposure to wood dust. However, the wood dust by sanding operation has not been investigated sufficiently. In this study, the generation rate and the particle size distribution of the wood dust produced by handheld sanding operation were observed by laboratory experiments. Methods: Beech and cypress were taken as typical hard and soft wood specimen respectively, and sanded with a portable sander. Three grades of sand paper (coarse, medium, fine) were attached to the sander in turn to be tested. The quantity of the wood dust produced by the sander was measured by weighing the specimen before and after the sanding and then the generation rate of the dust was calculated. Results: Soft wood generated more dust than hard wood due to the difference in abrasion durability. A coarse sand paper produced more dust than a fine sand paper. The particles of less than 1 μm diameter were scarcely observed in the wood dust. When the specimens were sanded with a fine sand paper, the mass median aerodynamic diameters of beech dust and cypress dust were 9.0 μm and 9.8 μm, respectively. Conclusions: Respirable wood dust is able to be controlled by general ventilation with more than 0.7-4.2 m3/min ventilation rate.

Field Study
  • Iman Dianat, Mohammad Ali Karimi
    2016 Volume 58 Issue 6 Pages 644-652
    Published: November 20, 2016
    Released: November 29, 2016
    [Advance publication] Released: September 30, 2016
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    Objectives: This study was conducted to determine the prevalence of musculoskeletal symptoms and associated risk factors among Iranian handicraft workers engaged in different hand sewing tasks. Methods: Data were collected using questionnaires (including the Nordic Musculoskeletal Questionnaire) as well as direct observations of posture (using the Rapid Upper Limb Assessment [RULA] method) from 632 workers including carpet handicraft workers (n=222), textiles handicraft workers (n=209), and leather handicraft workers (n=201) in Tabriz, Iran. Results: The response rate was 88.8%. The overall prevalence of musculoskeletal complaints, particularly in the neck (57.9%), lower back (51.6%), and shoulders (40.5%) was relatively high. The prevalence of neck and shoulder pain was higher among females and with increasing age. Working posture and fast working were associated with neck, shoulder, and lower back pain. Years worked as a sewing worker was associated with neck and lower back pain. Long duration of continuous sitting work (>2 h) without a break was associated with neck pain. Body mass index, marital status, sport/physical activity, smoking, daily working hours, job satisfaction, and perceived pressure due to work had no effect. Conclusions: The findings indicate a high prevalence of musculoskeletal pain among the studied handicraft workers and emphasize the importance of individual, physical, and psychosocial aspects of hand sewing tasks in this regard.

Opinion/Recommendation
  • Norio Sugawara, Manabu Saito, Kazuhiko Nakamura
    2016 Volume 58 Issue 6 Pages 653-655
    Published: November 20, 2016
    Released: November 29, 2016
    [Advance publication] Released: September 30, 2016
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    Since December 1, 2015, the Japanese government has required employers to conduct the Stress Check Program. The Ministry of Health, Labour and Welfare announced that this program should focus on the primary prevention of mental health problems. Although employers are obliged to perform screening for mental health problems and a physician's interview, employees are not mandated to participate in this program. Classical occupational health studies have accumulated evidence indicating that quantitative or qualitative workload is associated with mental health problems. Therefore, workload reduction is a major approach proposed for individuals with mental health problems; however, this approach exacerbates conflicts between mental health professionals and employers. We cannot achieve employers' understanding by only emphasizing that hard work can cause depression. Recently, the concepts of work engagement and organizational justice have spread in Japanese workplaces. Organizational justice is one of the necessary conditions for promoting positive mental health and can serve as a guiding compass for improving the work environment. If we can apply the Stress Check Program for the promotion of work engagement and organizational justice, the launch of this program could constitute a chance to improve this working environment. The Stress Check Program is not a process to search for and eliminate individuals with mental disorders.

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