Objectives:N,N-Dimethylacetamide (DMAC) is widely used in industry as a solvent. It can be absorbed through human skin. Therefore, it is necessary to determine exposure to DMAC via biological monitoring. However, the precision of traditional gas chromatography (GC) is low due to the thermal decomposition of metabolites in the high-temperature GC injection port. To overcome this problem, we have developed a new method for the simultaneous separation and quantification of urinary DMAC metabolites using liquid chromatography-tandem mass spectrometry (LC-MS/MS).
Methods: Urine samples were diluted 10-fold in formic acid, and 1-μl aliquots were injected into the LC-MS/MS equipment. A C18 reverse-phase Octa Decyl Silyl (ODS) column was used as the analytical column, and the mobile phase consisted of a mixture of methanol and aqueous formic acid solution.
Results: Urinary concentrations of DMAC and its known metabolites (N-hydroxymethyl-N-methylacetamide (DMAC-OH), N-methylacetamide (NMAC), and S-(acetamidomethyl) mercapturic acid (AMMA)) were determined in a single run. The dynamic ranges of the calibration curves were 0.05–5 mg/l (r ≥ 0.999) for all four compounds. The limits of detection for DMAC, DMAC-OH, NMAC, and AMMA in urine were 0.04, 0.02, 0.05, and 0.02 mg/l, respectively. Within-run accuracies were 96.5%–109.6% with relative standard deviations of precision being 3.43%–10.31%.
Conclusions: The results demonstrated that the proposed method could successfully quantify low concentrations of DMAC and its metabolites with high precision. Hence, this method is useful for evaluating DMAC exposure. In addition, this method can be used to examine metabolite behaviors in human bodies after exposure and to select appropriate biomarkers.
Background: Numerous workers have participated in recovery efforts following the accident that occurred at the Tokyo Electric Power Company (TEPCO) Fukushima Daiichi Nuclear Power Plant after the Great East Japan Earthquake. These workers, belonging to various companies, have been engaged in various tasks since the accident. Given the hazards and stress involved in these tasks and the relatively long time required to transport sick or injured workers to medical institutions, it became necessary to quickly implement a more stringent management program for fitness for duty than in ordinary work environments. Case: It took considerable time to introduce and improve a fitness-for-duty program because of several concerns. Various efforts were conducted, sometimes triggered by guidance from the Ministry of Health, Labour and Welfare (MHLW), but the implementation of the program was insufficient. In April 2016, a new program was initiated in which all primary contractors confirmed that their subcontractors had achieved five conditions for workers' fitness for duty on the basis of guidance from the MHLW and occupational health experts. TEPCO confirmed that all primary contractors had implemented the program successfully as of the end of November 2016. Conclusion: Following a disaster, even though the parties concerned understand the necessity of fitness-for-duty programs and that companies in high positions have responsibilities beyond their legal requirements, it is highly possible that they may hesitate to introduce such programs without guidance from the government. It is necessary to prepare a governmental framework and professional resources that introduce these stringent management programs quickly.
The study was conducted to report on the scope and prevalence of occupational health related-problems experienced by dentists, dental therapists, and oral hygienists in their practice of dentistry.
Background: Professional practice and dental training have many risk factors, and the dental team should be able to recognize these factors to protect themselves. The prevalence of conditions related to the musculoskeletal system, stress, percutaneous injuries, ears, and eyes are of concern. The dental team should also not forget hepatitis B, hepatitis C, and HIV as risks in practice. Dental practitioners should protect themselves by self-recognizing risk factors and by maintaining proper working conditions.
Methods: The study targeted all empirical research, case studies, and systematic literature reviews written in English. All articles selected were subjected to a data analysis process. Data were captured on an Excel spreadsheet and reported in a comprehensive table.
Results: The literature addressing occupational health among dental practitioners included mainly cross-sectional studies and review papers (2001–2016). Forty-nine studies were included in the review. Musculoskeletal disorders remain the most researched occupational health–related problems in dentistry. Eye protection compliance was low among practitioners. Percutaneous injuries especially among young dentists and students were still a concern.
Conclusion: Occupational health–related problems are still prevalent in current dentistry practice, despite changes in equipment and surgery design. The reported prevalence of occupational related-health problems and other findings of investigative studies highlight the need for continuous professional education and a need to improve clinical practice aspects of dentistry curricula.
This Document, "Guidelines for personal exposure monitoring of chemicals" ("this Guideline"), has been prepared by "The Committee for Personal Exposure Monitoring" ("the Committee") of the Expert Division of Occupational Hygiene & Ergonomics, Japan Society for Occupational Health. Considering the background of the growing importance of personal exposure monitoring in risk assessment and the need to prepare for the introduction of monitoring using personal samplers from an administrative perspective in recent years, the Committee was organized in November 2012. The Committee has prepared this Guideline as a "practical guideline" for personal exposure monitoring, so as to offer proposals and recommendations to the members of the Japan Society for Occupational Health and to society in general. The scope of this Guideline covers all chemical substances and all related workplaces regarded as targets for general assessment and the management of risk. It thus is not to be considered to comment on legal regulations and methodology. The main text provides the basic methods and concepts of personal exposure monitoring, while 31 "Appendices" are provided in this Guideline throughout the series; technical descriptions, statistical bases, and actual workplace examples are provided in these appendices, to assist better understanding. The personal exposure monitoring described as per this Guideline is equivalent to an " expert-centered basic method to reasonably proceed with the assessment and management of risk at workplaces." It is considered that practicing and expanding on this method will significantly contribute in reforming the overall framework of occupational hygiene management in Japan.
Objectives: The translation of lifestyle intervention to improve glucose tolerance into the workplace has been rare. The objective of this meta-analysis is to summarize the evidence for the effectiveness of dietary interventions in worksite settings on lowering blood sugar levels.
Methods: We searched for studies in PubMed, Embase, Econlit, Ovid, Cochrane, Web of Science, and Cumulative Index to Nursing and Allied Health Literature. Search terms were as follows: (1) Exposure-based: nutrition/diet/dietary intervention/health promotion/primary prevention/health behavior/health education/food /program evaluation; (2) Outcome-based: diabetes/ hyperglycemia/glucose/HbA1c/glycated hemoglobin; and (3) Setting-based: workplace/ worksite/occupational/industry/job/employee. We manually searched review articles and reference lists of articles identified from 1969 to December 2016. We tested for between-studies heterogeneity and calculated the pooled effect sizes for changes in HbA1c (%) and fasting glucose (mg/dL) using random effect models for meta-analysis in 2016.
Results: A total of 17 articles out of 1663 initially selected articles were included in the meta-analysis. With a random-effects model, worksite dietary interventions led to a pooled −0.18% (95% CI, −0.29 to −0.06; P < 0.001) difference in HbA1c. With the random-effects model, the interventions resulted in 2.60 mg/dL lower fasting glucose with borderline significance (95% CI:–5.27 to 0.08, P = 0.06). In the multivariate meta-regression model, the interventions with high percent of female participants and that used the intervention directly delivered to individuals, rather the environment changes, were associated with more effective interventions.
Conclusion: Workplace dietary interventions can improve Hba1c. The effects were larger for the interventions with greater number of female participants and with individual-level interventions.
Objectives: Indium compounds are used in manufacturing displays of mobile phones and televisions. However, these materials cause interstitial pneumonia in exposed workers. Animal experiments demonstrated that indium compounds caused lung cancer. Chronic inflammation is considered to play a role in lung carcinogenesis and fibrosis induced by particulate matters. 8-Nitroguanine (8-nitroG) is a mutagenic DNA lesion formed during inflammation and may participate in carcinogenesis. To clarify the mechanism of carcinogenesis, we examined 8-nitroG formation in indium-exposed cultured cells.
Methods: We treated RAW 264.7 mouse macrophages with indium oxide (In2O3) nanoparticles (primary diameter: 30–50 nm), and performed fluorescent immunocytochemistry to detect 8-nitroG. The extent of 8-nitroG formation was evaluated by quantitative image analysis. We measured the amount of nitric oxide (NO) in the culture supernatant of In2O3-treated cells by the Griess method. We also examined the effects of inhibitors of inducible NO synthase (iNOS) and endocytosis on In2O3-induced 8-nitroG formation.
Results: In2O3 significantly increased the intensity of 8-nitroG formation in RAW 264.7 cells in a dose-dependent manner. In2O3-induced 8-nitroG formation was observed at 2 h and further increased at 4 h, and the amount of NO released from In2O3-exposed cells was significantly increased at 2–4 h compared with the control. 8-NitroG formation was suppressed by 1400W (an iNOS inhibitor), methyl-β-cyclodextrin and monodansylcadaverine (inhibitors of caveolae- and clathrin-mediated endocytosis, respectively).
Conclusions: These results suggest that endocytosis and NO generation participate in indium-induced 8-nitroG formation. NO released from indium-exposed inflammatory cells may induce DNA damage in adjacent lung epithelial cells and contribute to carcinogenesis.
Objectives: The purpose of this work was to investigate the fitness of the existing truck seats for Bangladeshi truck drivers and suggest a guideline for drivers' seats based on their anthropometry. Methodology: In this study, eight anthropometric measurements of 120 Bangladeshi truck drivers and seven seat dimensions of ninety trucks of three brands namely, TATA, ASHOK LEYLAND, and ISUZU were considered for investigating the considerable mismatch between seat dimensions and drivers' anthropometry. The data were analyzed using two-sample t-tests to identify the relationship between existing seat dimensions and drivers' anthropometry. Results: The results showed a mismatch in seat dimensions and anthropometric measurements for nearly all truck brands and the existing seat dimensions were found to be inappropriate for Bangladeshi drivers. For all the truck brands, the percentage mismatch of seat height, seat depth, seat width, backrest height, and steering wheel clearance varied between 71% and 98%, 23% and 79%, 33% and 84%, 28% and 65%, and 53% and 100% respectively. Subsequently, an attempt was made to provide ergonomically correct seat dimensions for Bangladeshi truck drivers. Further, generalized equations to design the appropriate seat dimensions were developed using the least square regression technique. The recommended seat height, depth and width, backrest height, and steering wheel clearance were found to be appropriate for 82%, 79%, 76%, 98%, and 100% of drivers respectively. Conclusion: The analysis and results of this study can be useful in developing guidelines for design and manufacture of truck driver seats in Bangladesh.
Objective: To report trends underreporting levels of occupational illnesses (OI) in Mexico from 2000 to 2015.
Methods: An ecological study was conducted. Data on OI was obtained from the Statistical Memories of the Mexican Institute of Social Security. We used univariate sensitivity analysis to estimate the average value and range.
Results: During the 2000–2015 period, the estimated average OI underreporting in the Mexican population was 89.1%; the minimum was 81.8% in 2015 and the maximum 95% in 2007, with an annual decrement rate of 1% (p < 0.05) was observed from 2007 to 2015.
Conclusions: Important changes to improve reporting of OI have taken place since 2007, most likely due to the implementation of new policies in this matter. Even though the OI report in Mexico is higher than what the World Health Organization estimates for Latin America (18% in 2015), activities to address this problem remain insufficient. Furthermore, it is important to evaluate the current process of identification and registration of OI in order to identify those that need reinforcement, to guarantee adherence to regulations, to consolidate training systems, and importantly, to develop the governing capacity of the sanitation and labor authorities to exercise their coordinating and regulatory functions.
Objectives: The purposes of this study were to clarify 1) the prevalence of foot and ankle pain and 2) the factors associated with foot and ankle pain among nurses. Methods: Nurses working at a university hospital in Japan were recruited to participate in this cross-sectional, questionnaire-based study. The occurrence of foot and ankle pain in the previous month was assessed by using the Standardized Nordic Questionnaire and the Manchester Foot Pain and Disability Index. Subjects also answered questions on footwear-related factors, including using the visual analog scale for shoe comfort. In addition, information on personal factors and psychosocial factors was collected using the Job Content Questionnaire. The relationships between the presence of foot and ankle pain and the associated factors were examined using multiple logistic regression analysis. Results: Responses of 636 nurses (response rate, 67%) were included for analysis. The prevalence of foot and ankle pain was 23% and 51% when using the Standardized Nordic Questionnaire and the Manchester Foot Pain and Disability Index, respectively. The prevalence of pain that prevented the nurses from performing activities of daily living and work was 4% and 17%, respectively. A low level of shoe comfort, personal factors (age and body mass index), and psychosocial factors (low job control and high job strain) was independently associated with the presence of foot and ankle pain. Conclusions: Foot and ankle pain occurred frequently in nurses. Shoe comfort, personal factors, and psychosocial factors were associated with foot and ankle pain.
Objective: To report the case of a fisherman who developed chronic mercury poisoning due to excessive consumption of tuna while working on a pelagic fishing vessel. Case report: A 48-year-old male deep-sea fisherman developed paresthesia and pain in both legs while working at sea. He continued working for over 4 months on a pelagic fishing vessel but was eventually unable to function normally as his condition deteriorated. Upon arrival on land, he received specialist treatment, including imaging studies, for 2 months; however, the cause of the symptoms was not identified. An examination of his occupational history revealed that he had worked as a crew member on a pelagic fishing vessel catching tuna for the last 2 years and consumed tuna for two or more meals per day, every day. Two months after discontinuation of tuna consumption, he was tested for mercury. The result showed an elevated blood mercury level (BML) of 21.79 μg/L. Based on the half-life of mercury, the BML was evaluated as 38.70–53.20 μg/L when he was on board. Four months after discontinuing tuna consumption, his BML decreased to 14.18 μg/L, and the symptoms were almost ameliorated. The person responsible for preparing meals on a pelagic fishing ship should be aware that fish may contain high levels of heavy metals and should prepare meals for crew members according to the recommended levels. Crew members should also be aware that fish and shellfish may contain mercury, and hence, they should consume only an appropriate amount.
Objectives: Neurotoxicity of 1-bromopropane (1-BP) has been reported in occupational exposure, but whether the chemical exerts developmental neurotoxicity is unknown. We studied the effects of prenatal 1-BP exposure on neuronal excitability in rat offspring. Methods: We exposed dams to 1-BP (700 ppm, 6 h a day for 20 days) and examined hippocampal slices obtained from the male offspring at 2, 5, 8, and 13 weeks of age. We measured the stimulation/response (S/R) relationship and paired-pulse ratios (PPRs) of the population spike (PS) at the interpulse intervals (IPIs) of 5 and 10 ms in the CA1 subfield. Results: Prenatal 1-BP exposure enhanced S/R relationships of PS at 2 weeks of age; however, the enhancement diminished at 5 weeks of age until it reached control levels. Prenatal 1-BP exposure decreased PPRs of PS at 2 weeks of age. After sexual maturation, however, the PPRs of PS increased at 5-ms IPI in rats aged 8 and 13 weeks.
Conclusions: Our findings indicate that prenatal 1-BP exposure in dams can cause delayed adverse effects on excitability of pyramidal cells in the hippocampal CA1 subfield of offspring.
Objectives: We aimed at testing a model of the direct and indirect effects of being a part-time farmer on the probability of being involved in an agricultural machinery-related accident, considering the role played by unsafe beliefs and the frequency of use of machinery.
Methods: Two-hundred and fifty-two Italian men, regular users of agricultural machinery (age: Mean = 45.1 years, standard Deviation = 17.5), were administered a paper-and-pencil questionnaire addressing their relation with work, unsafe beliefs, and previous experience of machinery-related accidents.
Results: Being a part-time farmer showed a positive association with unsafe beliefs only among occasional machinery users. Unsafe beliefs in turn showed a positive association with accidents.
Conclusions: The study gave a novel contribution to the knowledge of the chain of events connecting part-time farmers with machinery-related accidents. Preventive training interventions targeting part-timer farmers using agricultural machinery just occasionally should be developed.
On December 1, 2015, the Japanese government launched the Stress Check Program, a new occupational health policy to screen employees for high psychosocial stress in the workplace. As only weak evidence exists for the effectiveness of the program, we sought to estimate the risk of stress-associated long-term sickness absence as defined in the program manual.
Participants were 7356 male and 7362 female employees in a financial service company who completed the Brief Job Stress Questionnaire (BJSQ). We followed them for 1 year and used company records to identify employees with sickness absence of 1 month or longer. We defined high-risk employees using the BJSQ and criteria recommended by the program manual. We used the Cox proportional regression model to evaluate the prospective association between stress and long-term sickness absence.
During the follow-up period, we identified 34 male and 35 female employees who took long-term sickness absence. After adjustment for age, length of service, job type, position, and post-examination interview, hazard ratios (95% confidence intervals) for incident long-term sickness absence in high-stress employees were 6.59 (3.04-14.25) for men and 2.77 (1.32-5.83) for women. The corresponding population attributable risks for high stress were 23.8% (10.3-42.6) for men and 21.0% (4.6-42.1) for women.
During the 1-year follow-up, employees identified as high stress (as defined by the Stress Check Program manual) had significantly elevated risks for long-term sickness absence.
Objectives: Prolonged sitting with a flexed back and neck is recognized as being associated with an increased risk of neck and back pain disorders among overhead crane operators. The aim of this study was to compare back and head postures over a full shift of work between operators who experience back and neck pain, and healthy operators. Methods: In a first phase, the prevalence of musculoskeletal symptoms was assessed using the Nordic questionnaire among 120 crane operators. Based on first phase results, 17 operators with back/neck disorders were matched with 15 healthy operators based on age and selected to participate in the second phase of the study. Postures and movements were continuously measured over an 8 h shift using inclinometers. Results: The highest 12-month prevalence of musculoskeletal disorders was found in the lower back, neck and knees. Case and control groups differed significantly in back and head flexion angles at the 50th percentiles APDF (p < 0.05). There was also a significant difference in the time spent working in an extreme posture of the back and head between groups (p < 0.05). Conclusions: This is the first study to document work postures assumed during a full work shift and to compare postures between symptomatic and healthy overhead crane operators. Physical exposure in case group operators was characterized by more awkward and extreme postures in the back and head. The results of this study demonstrate that effective prevention strategies directed towards musculoskeletal disorders are required that address awkward work postures for overhead crane operators.
Objectives: This report reviews the carcinogenicity of multi-walled carbon nanotubes (MWCNTs) in experimental animals, concentrating on MWNT-7, a straight fibrous MWCNT. Methods: MWCNTs were administered to mice and rats by intraperitoneal injection, intrascrotal injection, subcutaneous injection, intratracheal instillation and inhalation. Results: Intraperitoneal injection of MWNT-7 induced peritoneal mesothelioma in mice and rats. Intrascrotal injection induced peritoneal mesothelioma in rats. Intratracheal instillation of MWCNT-N (another straight fibrous MWCNT) induced both lung carcinoma and pleural mesothelioma in rats. In the whole body inhalation studies, in mice MWNT-7 promoted methylcholanthrene-initiated lung carcinogenesis. In rats, inhalation of MWNT-7 induced lung carcinoma and lung burdens of MWNT-7 increased with increasing concentration of airborne MWNT-7 and increasing duration of exposure. Conclusions: Straight, fibrous MWCNTs exerted carcinogenicity in experimental animals. Phagocytosis of MWCNT fibers by macrophages was very likely to be a principle factor in MWCNT lung carcinogenesis. Using no-observed-adverse-effect level-based approach, we calculated that the occupational exposure limit (OEL) of MWNT-7 for cancer protection is 0.15 μg/m3 for a human worker. Further studies on the effects of the shape and size of MWCNT fibers and mode of action on the carcinogenicity are required.
Objectives: Human resources (HR) are essential indicators of safety and health (SH) status, and HR can be key sources of workplace safety management such as safety and health education at work (SHEW). This study analyzed significant HR factors associated with SHEW of small manufacturing businesses in Korea. Methods: The secondary data of the 2012 Korea Occupational Safety and Health Trend Survey were used to achieve this research purpose. A total of 2,089 supervisors or managers employed in the small manufacturing businesses completed the interview survey. Survey businesses were selected by multiple stratified sampling method based on industry code, business size, and region in Korea. The survey included workplace characteristics of HR and SHEW. Results: SHEW was significantly related to business size, occupational injury incidence in the previous year, foreign and elderly worker employment, presence of site supervisors, and presence of SH committees (p <.05). SHEW for office workers, non-office workers, and newcomers was associated with business size, presence of site supervisors, and presence of SH committees in logistic regression analysis (p <.001). Businesses with 30–49 workers conducted SHEW 3.64 times more than did businesses with 5 to fewer than 10 workers. The companies that had occupational injuries in the previous year conducted SHEW 1.68 times more than the others. The businesses that had site supervisors and committees conducted SHEW 2.30 and 2.18 times more, respectively, than others. Conclusions: Site supervisors and SH committees were significant HR factors that improved SHEW in small manufacturing businesses.
Background: It has been difficult to make reliable hazard assessments of manufactured nanomaterials, because the nanomaterials form large agglomerations in both in vitro and in vivo studies. Objective: A project by the New Energy and Industrial Technology Development Organization (NEDO) of Japan has succeeded in ensuring the stability of dispersion (nanoscale <100 nm) of manufactured nanomaterials, and is developing hazard assessments of manufactured nanomaterials. Results and Conclusion: Focusing on titanium dioxide, fullerenes and carbon nanotubes, we introduce findings made in inhalation and intratracheal installation studies overseas, and together with the findings made in the NEDO project, and also assess the hazards presented by manufactured nanoparticles.