Low back disorders (LBDs) are the most common musculoskeletal problem among farmers, with higher prevalence rates than in other occupations. Operators of tractors and other farm machinery such as combines and all terrain vehicles (ATV) can have considerable accumulation of exposure to whole body vibration (WBV). The causal relationship between LBDs and WBV is not fully clear; however, it may be different among farmers as their work context and exposure is unique. Objectives: The objectives of the two studies which form two manuscripts or chapters in this thesis were to: 1) investigate the associations between WBV and LBDs among farmers using a) systematic review (manuscript 1) and cohort studies (manuscript 2). Methods: Objective 1: Nine databases were searched using groups of terms for two concepts: ‘farming’ and ‘low back disorder’. Screening, data extraction and quality assessment was performed by two reviewers independently. The population was adult farmers or agricultural workers globally irrespective of sex. The intervention was considered to be WBV exposure, such tractor, combine and ATV use. The control was no exposure or low exposure to WBV and the outcome was low back disorders. No limits in date of publication and type of study design were applied in the literature search, and only full text, English language studies were considered. Objective 2: The data source was the Saskatchewan Farm Injury Cohort Study. In 2007, baseline data were collected on accumulated yearly tractor, combine, ATV operation, as well as several biopsychosocial covariates thought to be associated with LBDs. Follow-up data on LBDs and related symptoms were collected during 2013 (6 year follow-up) and 2014 (1-year). This resulted in two datasets for each of two cohorts: 1) the first cohort with 1,149 farm people who had been followed for six years, and 2) the second with 605 participants who had been followed for one year. Generalized estimating equation-modified Poisson regressions were performed with low back and hip symptoms as the outcome. Results: Objective 1: After 276 full texts screened, we found 12 articles which analyzed WBV as a risk factor for LBD. Three were case-control, 6 cross-sectional and 3 retrospective cohorts. Four studies showed no association between WBV and LBDs, 4 studies showed a positive association and for the remaining 4 studies, results were mixed depending on the exposure or the outcome measure. Objective 2: The adjusted model in cohort 1 found LBDs to be associated to tractor operation for 1-150 hrs/year (RR=1.23, 95%CI 1.05-1.44), 151-400 hrs/year (RR=1.32, 95%CI 1.14-1.54) and 401+ hrs/year (RR=1.34, 95%CI 1.15-1.56). In addition, tractor operation for 151-400 hrs/year (RR=1.95, 95%CI 1.45-2.62) and 401+ hrs/year (RR=1.79, 95%CI 1.32-2.45) was also found to be related to hip symptoms. Although combine operation ≥ 61 hrs/year and ATV operation 81+ days/year was related to LBD in the bivariate analysis in cohort 1, this association did not persist after adjustment for confounders. Due to limited power, no significant bivariate association was found between WBV and either LBDs and hip symptoms in cohort 2. Conclusions: Objective 1: A firm conclusion is difficult due to heterogeneity in statistical strategy, LBDs definition, type of farm commodity, and study design. Direct comparisons and synthesis were not possible. Although retrospective cohort studies tended to show a relationship, future studies with a prospective cohort design can help clarify this association further. Objective 2: Although duration of tractor operation and older age showed with both LBDs and hip symptoms in farmers in cohort 1, the true prospective cohort 2 found no significant association between WBV and LBDs.

No description available.

Introduction: Occupational drivers of terrain vehicles are exposed to several risk factors associated with musculoskeletal symptoms in the lower back as well as in the neck and upper limbs. Vibration has been suggested to be a main risk factor. These drivers are exposed to both whole-body vibration (WBV) and hand-arm vibration (HAV). Aim: This study establishes the association between driving terrain vehicles and musculoskeletal disorders (MSDs) in the neck and upper limbs as well as hand-arm vibration syndrome (HAVS). In addition, this study examines the effect on muscles in the neck and upper limbs of the type of vibration exposure that occurs in occupational driving of terrain vehicles. Methods and results: In Paper I, a cross-sectional questionnaire study on occupational drivers of terrain vehicles, increased Prevalence Odds Ratios (POR) were found for numbness, sensation of cold and white fingers (POR 1.5-3.9) and for MSDs in the neck (POR 2.1-3.9), shoulder (POR 1.8-2.6) and wrist (POR 1.7-2.6). For the shoulders, neck and elbow, there appears to be a pattern of increased odds with increasing exposure time. In Paper II, an experimental study on the trapezius muscle, which included 20 men and 17 women, the mean frequency of the electromyography signal (EMGMNF) decreased significantly more in a three minute sub-maximal contraction without vibration (-3.71Hz and -4.37Hz) compared to with induced vibration (-3.54Hz and -1.48Hz). In Paper III, a higher initial increase of the mean of the root-mean-square of the electromyography signal (EMGRMS) was seen in a three minute sub-maximal contraction with vibration exposure compared to without vibration (0.096% vs. 0.045%). There was a larger mean EMGMNF decrease for NV compared to V in the total three minutes, and a larger decrease also in the first time period was seen for the NV compared to V. A small gender effect was also noticed. In Paper IV, the combination of HAV and WBV was studied in laboratory settings and resulted in a higher trapezius EMGRMS compared to the HAV and WBV separately. Conclusion: Occupational drivers of terrain vehicles are likely to experience symptoms related to HAVS and musculoskeletal symptoms in the neck and upper limbs. Local vibration does not seem to have any negative acute effects on trapezius muscle fatigue. Vibration exposure seems to cause an initial increase in muscle activity in the trapezius that could be related to recruitment on new motor-units. A combination of HAV and WBV causes a larger muscular demand on the trapezius muscle.

No description available.

Individuals who sustain a spinal cord injury (SCI) experience sublesional osteoporosis (SLOP) which affects the bones of the lower extremities. As a result, these bones become fragile and susceptible to fractures. To tackle SLOP pharmacological and rehabilitation interventions have been proposed; however few have produced a significant and sustainable increase in bone mineral density (BMD). This study investigated whole-body vibration (WBV) as an alternative to tackling SLOP in SCI. Two commercially available vibration platforms, WAVE® and Juvent™, were tested for feasibility and efficacy in the SCI population. The effects of knee angle, frequency and amplitude of vibration in propagation characteristics were also assessed. The results demonstrated that variations in frequency generate the most noticeable changes in propagation characteristics, followed by variations in knee angle and amplitude. The recommended vibration parameters which could potentially have the greatest osteogenic effect on the bones of the lower extremity are 160o, 45 Hz, and 0.6 mm on the WAVE® platform.

Um die Beeinflussbarkeit des osteoporotischen Lendenwirbelkörpers der Ratte durch vertikale und horizontale Ganzkörpervibrationen (WBV) unterschiedlicher Frequenzen zu untersuchen, wurde ein Kollektiv aus 90 drei Monate alten Ratten (Gattung Sprague Dawley) gebildet. Von diesen Tieren bildeten 15 Ratten die gesunde SHAM-Gruppe. 75 Tiere wurden ovariektomiert und zu je 15 Tieren auf die Gruppen OVX und die einer WBV unterzogenen Gruppen 35 Hz vertikal, 70 Hz vertikal, 35 Hz horizontal, 70 Hz horizontal aufgeteilt. 61 Tage nach erfolgter Ovariektomie wurde mit der WBV (zweimal täglich für 15 Minuten) über einen Zeitraum von 31 aufeinander folgenden Tagen begonnen. Nach Durchführung der WBV wurden die Versuchstiere durch Dekapitation getötet, die einzelnen Wirbelkörper präpariert und den jeweiligen Untersuchungen zugeführt. Die Knochenmineraldichte und der Anteil an Kalzium und Phosphat wurden am zweiten Lendenwirbelkörper durch Veraschung bzw. Flammatomabsorptionsspektroskopie/Photometrie ermittelt. Um die biomechanischen Parameter zu untersuchen, wurde der vierte Lendenwirbelkörper in toto einem axialen Kompressionstest unterzogen. Durch Analyse des dritten Lendenwirbelkörpers mittels Mikro-CT konnte Aufschluss über das trabekuläre Netzwerk sowie das Volumen und die Knochenmineraldichte erlangt werden. Anschließend wurden die Ergebnisse aus Veraschungsversuch und Mikro-CT mit den biomechanischen Parametern korreliert, um so die Determinanten eines stabileren Knochens zu identifizieren. In dieser Studie konnte ein signifikanter negativer Einfluss des Östrogenmangels auf die biomechanische Stabilität sowie die Knochenmineraldichte, das Knochenvolumen und Trabekeldicke des Knochens gezeigt und der Nutzen einer WBV als nicht-medikamentöse Therapieoption des osteoporotischen Knochens belegt werden. Die bei 35 Hz vibrierten Tiere erlangten bezüglich der biomechanischen Stabilität (Fmax, Streckgrenze, Steigung) und der Knochenmineraldichte (total BMD) das Niveau der gesunden SHAM-Tiere. Die horizontale WBV konnte keinen eindeutigen Effekt auf die erhobenen Parameter zeigen. Durch den berechneten Korrelationskoeffizienten konnte die Abhängigkeit der biomechanischen Stabilität des Wirbelkörpers von der mittels Mikro-CT ermittelten Trabekeldicke, dem Knochenvolumen und der Knochenmineraldichte dargestellt werden. Somit kann von den durch Bildgebung erhobenen Daten direkt auf die biomechanische Belastbarkeit und die Frakturneigung geschlossen werden. In dieser Studie konnten der Einfluss und Nutzen einer vertikalen 35 Hz WBV auf den osteoporotischen Lendenwirbelkörper der Ratte gezeigt werden. Die Bestätigung der Ergebnisse am Großtiermodell stellt ebenso wie die Durchführung klinischer Studien Ziele für die Zukunft dar, um den Nutzen einer WBV als schonende nicht-medikamentöse Therapieform der Osteoporose zu betätigen.

The phrase “miner” is comparatively non-specific as mining is seen as a multi-disciplinary industry that includes several diverse professions and trades (Donoghue, 2004). One of the functions within mining is the operation of earth moving equipment (EME) such as haul trucks, dozers, excavators and graders. EME are generally used to shift large amounts of earth, dig foundations and landscape areas. In this study whole-body vibration (WBV) and noise exposure of earth moving equipment (EME) operators were assessed, at an opencast coalmine in South Africa. The aim was to evaluate and quantify the levels of exposure in different EME types, as well as to compare old with new EME, in order to estimate if machine hours contribute to higher noise and vibration levels. WBV and noise levels of the Production and Rehabilitation operations were compared, to determine whether different activities led to different exposures. Internationally accepted standardised methods, ISO 2631-1 for WBV and SANS 10083:2012 for noise were followed and correctly calibrated instrumentation was used. WBV measurements were conducted with a tri-axial seat pad accelerometer (SVAN 958) and personal noise dosimeters (Casella 35 X) were used for noise measurements. Measurements were taken over a period of four months. With regards to the European Union (EU) limit (1.15 m/s2) and the EU action limit (0.5 m/s2) it was noted that operators of EME within the Production operation were not exposed to WBV levels above the EU limit, but 77% of these operators were exposed to WBV levels above the EU action limit. It was also evident that 45% of operators’ vibration exposure levels were within the Health Guidance Caution Zone (HGCZ) of 0.45 – 0.90 m/s2. Within the Rehabilitation operation, 9% of operators were exposed to WBV levels above the EU limit and 55% above the EU action limit. Furthermore 50% was within the HGCZ. With regards to the noise Occupational exposure limit (OEL) of 85 dB(A) as stated by the Mine Health and Safety Regulations (MHSR) it was noted that 27% of operators within the Production operation were exposed to noise levels above the limit and for operators within the Rehabilitation operation 14% were reported to be exposed at or above the limit. Statistically significant difference in noise exposure was found between the Production operation and Rehabilitation operation. Results indicated that the majority of EME operators were exposed to high noise levels, in some cases exceeding the 85 dB(A) OEL. A significant positive correlation was found between noise exposure levels and machine hours. Thus higher noise levels were observed as machine operating hours increased. It was found that operators were exposed predominantly to vibration and noise levels below the limits. However the Dozer group within the Production and Rehabilitation operations in some cases exceeded the vibration and noise legal limit. High exposure levels within the Dozer group can be attributed to the fact that these EME types mostly perform activities in uneven areas and the tracks on which these Dozers move also contribute to higher vibration levels due to a lack of a suspension. Controls should be implemented as far as is reasonably practicable to ensure that operators are not exposed above recommended or permissible levels for each hazard. Continuous improvement of the maintenance plan for all EME and regularly grading and maintaining travelling ways are some of the controls that will contribute to lower vibration and noise levels. Operators exposed to high noise levels should use hearing protective devices as an early on preventative measure to reduce noise exposure levels. / MSc (Occupational Hygiene), North-West University, Potchefstroom Campus, 2014

No description available.

Radiobiological irradiation can be performed using appropriately collimated sealed source radioisotope machines such as Co-60 units, as well with X-ray tubes and linear accelerators. The increasing research interest in delivering organ-specific or whole body animal external irradiation has led to the introduction of dedicated X-ray units for research purposes. In this work, the proprieties of a kilovoltage X-ray biological irradiator, the Faxitron cabinet X-ray system model CP160, are investigated and dosimetrically characterized. Calculation formalisms for everyday use of the radiobiological irradiator in laboratory conditions, specifically for cell cultures and small animals total body irradiation, were developed following the AAPM TG-61 protocol. The quality of the X-ray beams generated by this irradiator was found to range between HVL 0.7 mm Cu for a 160 kVp 0.5 mm Cu filtered beam, and HVL 0.07 mm Al for a 20 kVp non-filtered beam. Our calculation formalisms for cell cultures and small animal irradiations were found to be valid within +/-5%.

Individuals who sustain a spinal cord injury (SCI) experience sublesional osteoporosis (SLOP) which affects the bones of the lower extremities. As a result, these bones become fragile and susceptible to fractures. To tackle SLOP pharmacological and rehabilitation interventions have been proposed; however few have produced a significant and sustainable increase in bone mineral density (BMD). This study investigated whole-body vibration (WBV) as an alternative to tackling SLOP in SCI. Two commercially available vibration platforms, WAVE® and Juvent™, were tested for feasibility and efficacy in the SCI population. The effects of knee angle, frequency and amplitude of vibration in propagation characteristics were also assessed. The results demonstrated that variations in frequency generate the most noticeable changes in propagation characteristics, followed by variations in knee angle and amplitude. The recommended vibration parameters which could potentially have the greatest osteogenic effect on the bones of the lower extremity are 160o, 45 Hz, and 0.6 mm on the WAVE® platform.