A unique Institute of Railway Hygiene was created 70 years ago in Russia, one of the major railway countries in the world. Since then the Institute's staffers have carried out huge work on improvement of railway workers' health, prevention of their exposure to noise, unfavorable microclimate, vibration and other occupational hazards. Significant contribution into the world occupational hygiene was made by such Institute's professionals as S.F. Kazansky, P.I. Nikitin, A.M. Volkov and others.
The objective of this cross-sectional study was to study associations between low back pain (LBP) and modes of transport to school and leisure activities among adolescents. The study population included all adolescents in eighth and ninth grade in two geographic areas in eastern Norway. Eighty-eight adolescents participated (mean age 14.7 years), making the response rate 84%. Data concerning active (walking/bicycling) and passive (bus/car) journeys were obtained from lists and maps from local authorities, and from the pupils, using a questionnaire that also included LBP, activities and wellbeing. Distance walked/bicycled to school was slightly shorter among those reporting LBP in bivariate analyses. Walking/bicycling more than 8 km weekly to regular activities was inversely associated with LBP in multivariate analysis (OR 0.3; 95% confidence interval 0.1-1.0). No associations were found between passive journeys and LBP. The results raise the question for future research of whether lack of active transport may be one cause behind the increase in juvenile LBP.
This study investigates possible acute effects on heart rate variability (HRV) when people are exposed to hand transmitted vibration and noise individually and simultaneously.
Ten male and 10 female subjects were recruited by advertisement. Subjects completed a questionnaire concerning their work environment, general health, medication, hearing, and physical activity level. The test started with the subject resting for 15 min while sitting down. After resting, they were exposed to one of four exposure conditions: (1) only vibration; (2) only noise; (3) both noise and vibration; or (4) a control condition of exposure to the static load only. All four exposures lasted 15 min and the resting time between the exposures was 30 min. A continuous electrocardiogram (ECG) signal was recorded and the following HRV parameters were calculated: total spectral power (P(TOT)); the spectral power of the very low frequency component (P(VLF)); the low frequency component (P(LF)); the high frequency component (P(HF)); and the ratio LF/HF.
Exposure to only vibration resulted in a lower P(TOT) compared to static load, whereas exposure to only noise resulted in a higher P(TOT). The mean values of P(TOT), P(VLF), P(LF), and P(HF) were lowest during exposure to vibration and simultaneous exposure to vibration and noise.
Exposure to vibration and/or noise acutely affects HRV compared to standing without these exposures. Being exposed to vibration only and being exposed to noise only seem to generate opposite effects. Compared to no exposure, P(TOT) was reduced during vibration exposure and increased during noise exposure.
A study was performed of vibration disease prevalence and morbidity dynamics for 10 years at the enterprises of the RSFSR Ministry of Machine-Building Industry. The results of the study proved that the major VD prevalence was found in automobile, heavy and energy machinery industries, machine-tool and agriculture machinery industry (80%). With regard to the morbidity rate and duration of work/D morbidity correlation, the contributors identified 8 major VD-risk professions, including those for female workers, an earlier development of the disease being more characteristic of females in some professional groups. It was established that some are less/or more liable to VD in comparison with others of the same professional group, which can be accounted for by different individual factors that influence the latent development of the disease. The revealed differences can determine the most promising techniques in VD prevention at machine-engineering plants.
Whole-body vibration measurements were recorded for various types of heavy equipment used within the construction industry. The purpose of these measurements was to provide more information about the potential levels of whole-body vibration experienced by equipment operators in the construction industry, as well as to identify types of equipment warranting further research. In total, 67 pieces of equipment were tested from 14 different equipment types. Testing took place at various construction sites including corporate, public, and residential work projects. Measurements were made (following the 1997 International Standards Organization's 2631-1 whole-body vibration standards) for 20-minute testing periods using a Larson Davis HVM100 vibration monitor and a triaxial accelerometer. The mobile equipment tested was associated with greater levels of whole-body vibration than the stationary equipment. When whole-body vibration levels were compared to the International Standards Organization's 2631-1 standards, wheel loaders, off-road dump trucks, scrapers, skid steer vehicles, backhoes, bulldozers, crawler loaders, and concrete trowel vehicles exceeded the recommendations based on measured vibration dose values. Further research incorporating larger sample sizes and controlled testing conditions is required to better understand the levels of exposure experienced by operators as well as the amount to which seating, terrain, mobility, and vehicle structure might affect whole-body vibration.
Ergonomic Technology Center, University of Connecticut Health Center, Farmington, Connecticut 06030-2017 and Institute for Microstructural Sciences, National Research Council, Ottawa, Ontario K1A 0R6, Canada. firstname.lastname@example.org
Two tools for assessing tactile sensory disturbances in the hands have been constructed from mechanoreceptor-specific vibrotactile threshold shifts, and thresholds changes with time, and employed in a prospective study of forest workers (N=18). Statistically significant positive threshold shifts (i.e., reductions in sensitivity compared to the hands of healthy persons) were found in five hands at study inception (13.9%), and 15 hands at follow-up (41.7%). Four patterns of threshold shift could be identified, involving selectively the median and/or ulnar nerve pathways and/or end organs. Statistically significant positive threshold changes (i.e., reductions in sensitivity with time) were recorded in 69.4% of the hands over a five-year period, even though a majority of the workers remained symptom free. If the thresholds recorded from subjects not working with power tools are used to control for aging, lifestyle, and environmental factors during the five year period, then 40% of the remaining subjects are found to be experiencing work-related threshold changes in their hands. The ability of the threshold shift metric to predict the numbness reported by these subjects shows that it is closely associated with the tactile sensory changes occurring in their hands.
BACKGROUND: Modic changes are bone marrow lesions visible in magnetic resonance imaging (MRI), and they are assumed to be associated with symptomatic intervertebral disc disease, especially changes located at L5-S1. Only limited information exists about the determinants of Modic changes. The objective of this study was to evaluate the determinants of vertebral endplate (Modic) changes, and whether they are similar for Modic changes and severe disc degeneration focusing on L5-S1 level. METHODS: 228 middle-aged male workers (159 train engineers and 69 sedentary factory workers) from northern Finland underwent sagittal T1- and T2-weighted MRI. Modic changes and disc degeneration were analyzed from the scans. The participants responded to a questionnaire including items of occupational history and lifestyle factors. Logistic regression analysis was used to evaluate the associations between selected determinants (age, lifetime exercise, weight-related factors, fat percentage, smoking, alcohol use, lifetime whole-body vibration) and Modic type I and II changes, and severe disc degeneration (= grade V on Pfirrmann's classification). RESULTS: The prevalences of the Modic changes and severe disc degeneration were similar in the occupational groups. Age was significantly associated with all degenerative changes. In the age-adjusted analyses, only weight-related determinants (BMI, waist circumference) were associated with type II changes. Exposure to whole-body vibration, besides age, was the only significant determinant for severe disc degeneration. In the multivariate model, BMI was associated with type II changes at L5-S1 (OR 2.75 per one SD = 3 unit increment in BMI), and vibration exposure with severe disc degeneration at L5-S1 (OR 1.08 per one SD = 11-year increment in vibration exposure). CONCLUSION: Besides age, weight-related factors seem important in the pathogenesis of Modic changes, whereas whole-body vibration was the only significant determinant of severe disc degeneration.
The objective of this study was to determine the prevalence of hand-arm vibration syndrome (HAVS) in 617 workers at a base metal mine in northern Ontario. Workers who were employed at the mine between the years 1989 and 1994 and who continued to live within a 100 km radius of the mine were sent a self-reported questionnaire to identify individuals with possible vibration-induced symptoms in their upper extremities. Of the 162 workers who attended the medical examination, 50% were diagnosed with HAVS, 26% had other diagnoses with some workers having multiple afflictions e.g., both HAVS and carpal tunnel syndrome (CTS). No vibration-induced symptoms were reported in 35% of the workers who were clinically normal. The study was designed to educate, advise, and to make recommendations on the prevention of HAVS. Ongoing commitments to technological improvements, mandatory and regular rest periods, and continuing educational sessions on the syndrome should help to reduce the prevalence of this disease.
The article sets forth a theoretical basis for the evaluation of the probability of vibration disease caused by local vibration, with due account of the concomitant factors and with recommendations with regard to the assessment of the aggravating and normalizing factors. Basing on the original data and medical literature information, the contributors provided formulae and charts for the assessment of vibration disease, risks caused by noise, cold microclimate, physical overload, and cigarette smoking as an individual factor. A concept was proposed with regard to the risk-free dosage. The concept was viewed as a new hygienic and occupational category, which facilitated evaluating the real occupational risk levels for any profession and their consequent minimizing.