Occupational Health and Industrial Hygiene Commons^™

Stress State Analysis And Tensile-Shear Fracture Criterion In Combined Puncture And Cutting Of Soft Materials, Ennouri Triki, Chantal Gauvin

Études primaires

The mechanics of the combined puncture and cutting of protective materials by a pointed blade are studied theoretically and experimentally, by means of stress state analysis. Through analysis of the stresses occurring during the puncture cutting of a variety of neoprene and nitrile rubber membranes by pointed blades with different cutting-edge angles, a force state of pushing/shear-dependent loading is formulated and discussed. By considering this combined loading as an asymmetric fracture, two equations—for pushing force component and shear force component—are then derived from the stress intensity factors. From this stress analysis, a model based on fracture mechanics theory is developed …

The Current Burden Of Cancer Attributable To Occupational Exposures In Canada, France Labrèche, Joanne Kim, Chaojie Song, Manisha Pahwa, Calvin B. Ge, Victoria H. Arrandale, Christopher B. Mcleod, Cheryl E. Peters, Jérôme Lavoué, Hugh W. Davies, Anne-Marie Nicol, Paul A. Demers

Études primaires

Exposure to occupational carcinogens is often overlooked as a contributor to the burden of cancer. To estimate the proportion of cancer cases attributable to occupational exposure in Canada in 2011, exposure prevalence and levels of 44 carcinogens were informed by data from the Canadian carcinogen exposure surveillance project (CAREX Canada). These were used with Canadian Census (between 1961 and 2011) and Labour Force Survey (annual surveys between 1976 and 2013) data to estimate the number of workers ever exposed to occupational carcinogens. Risk estimates of the association between each carcinogen and cancer site were selected mainly from published literature reviews. …

The Effect Of Extensible And Non-Extensible Lumbar Belts On Trunk Postural Balance In Subjects With Low Back Pain And Healthy Controls, Ali Shahvarpour, Richard Preuss, Christian Larivière

Études primaires

Background

Previous findings suggest that wearing a lumbar belt may benefit some patients with low back pain; however, the mechanisms of action are not yet fully understood.

Research question

The effect of wearing two flexible (extensible and non-extensible) lumbar belts on trunk postural control was investigated during an unstable sitting task.

Methods

Healthy subjects and subjects with LBP sat on a wobbling chair, with and without the lumbar belts. Chair rotation was measured in the sagittal and frontal planes, and 10 linear and nonlinear measures of balance were computed to assess the quantity (3 measures) and quality (7 measures) of …

Ultrasound Measures Of The Abdominal Wall In Patients With Low Back Pain Before And After An 8-Week Lumbar Stabilization Exercise Program, And Their Association With Clinical Outcomes, Christian Larivière, Sharon M. Henry, Dany H. Gagnon, Richard Preuss, Jean-Pierre Dumas

Études primaires

Background

Lumbar stabilization exercise programs (LSEPs) act positively on clinical outcome measures in patients with low back pain (LBP), but the underlying mechanisms are not well understood. Among the various neuromuscular mechanisms, a good candidate is better activation of the abdominal wall, as measured with rehabilitative ultrasound imaging (RUSI).

Objectives

To determine whether RUSI measures are (1) sensitive to LBP status and treatment (LSEP) and (2) correlate with clinical outcomes following the LSEP.

Design

An exploratory one-arm clinical trial with healthy participants as a control group.

Setting

LSEP was delivered in a clinical setting; outcomes were measured in a laboratory …

Use Of Magnetic Resonance Image Registration To Estimate Displacement In The Human Earcanal Due To The Insertion Of In-Ear Devices, Simon Benacchio, Olivier Doutres, Arthur Varoquaux, Éric Wagnac, Arnaud Le Troter, Virginie Callot, Franck Sgard

Études primaires

In-ear devices are used in a wide range of applications for which the device's usability and/or efficiency is strongly related to comfort aspects that are influenced by the mechanical interaction between the device and the walls of the earcanal. Although the displacement of the earcanal walls due to the insertion of the device is an important characteristic of this interaction, existing studies on this subject are very limited. This paper proposes a method to estimate this displacement in vivo using a registration technique on magnetic resonance images. The amplitude, the location and the direction of the earcanal wall displacement are …

Exposure To Polybrominated Diphenyl Ethers (Pbdes) In American And Canadian Workers: Biomonitoring Data From Two National Surveys, Sabrina Gravel, Jérôme Lavoué, France Labrèche

Études primaires

Polybrominated diphenyl ethers (PBDEs) are flame retardants commonly found in many household and industrial products. They can be detected in the serum of the general population, and in even higher concentrations in workers of certain industries, due to an additional occupational exposure. The purpose of this analysis is to determine background exposure levels of PBDEs in the general working population, using national surveys where working status was self-reported. Participants aged 20–65 were selected from the 2003–2004 U.S. National Health and Nutrition Examination Survey (n = 1141) and the 2007–2009 Canadian Health Measures Survey (n = 1337). Only four congeners were …

Trunk Musculoskeletal Response In Maximum Voluntary Exertions: A Combined Measurement-Modeling Investigation, F. Ghezelbash, Z. El Ouaaid, A. Shirazi-Adl, A. Plamondon, N. Arjmand

Études primaires

Maximum voluntary exertion (MVE) tasks quantify trunk strength and maximal muscle electromyography (EMG) activities with both clinical and biomechanical implications. The aims here are to evaluate the performance of an existing trunk musculoskeletal model, estimate maximum muscle stresses and spinal forces, and explore likely differences between males and females in maximum voluntary exertions. We, therefore, measured trunk strength and EMG activities of 19 healthy right-handed subjects (9 females and 10 males) in flexion, extension, lateral and axial directions. MVEs for all subjects were then simulated in a subject-specific trunk musculoskeletal model, and estimated muscle activities were compared with EMGs. Analysis …

A Comparison Of Lumbar Spine And Muscle Loading Between Male And Female Workers During Box Transfers, Denis Gagnon, André Plamondon, Christian Larivière

Études primaires

There is a clear relationship between lumbar spine loading and back musculoskeletal disorders in manual materials handling. The incidence of back disorders is greater in women than men, and for similar work demands females are functioning closer to their physiological limit. It is crucial to study loading on the spine musculoskeletal system with actual handlers, including females, to better understand the risk of back disorders. Extrapolation from biomechanical studies conducted on unexperienced subjects (mainly males) might not be applicable to actual female workers. For male workers, expertise changes the lumbar spine flexion, passive spine resistance, and active/passive muscle forces. However, …

Estimation Of The Ear Canal Displacement Field Due To In-Ear Device Insertion Using A Registration Method On A Human-Like Artificial Ear, S. Benacchio, O. Doutres, A. Le Troter, A. Varoquaux, E. Wagnac, V. Callot, F. Sgard

Études primaires

Passive and active in-ear devices (IED) occluding the ear canal are commonly used to (i) protect people from high noise levels (earplugs), (ii) assist people suffering from hearing impairment (hearing aids) or (iii) help people in listening from their sound systems (earbuds). However, the usability and/or efficiency of IEDs can be greatly affected by several discomfort components (physical, acoustical and functional). The mechanical pressure exerted by the IED onto the ear canal walls is greatly suspected to affect the aforementioned comfort components. This physical characteristic is closely related to the displacement field induced by the IED insertion, which has to …

The Effects Of An 8-Week Stabilization Exercise Program On Lumbar Multifidus Muscle Thickness And Activation As Measured With Ultrasound Imaging In Patients With Low Back Pain: An Exploratory Study, Christian Larivière, Dany H. Gagnon, Sharon M. Henry, Richard Preuss, Jean-Pierre Dumas

Études primaires

Background

Lumbar stabilization exercise programs (LSEP) produce positive effects on clinical outcomes, but the underlying mechanisms remain relatively unexplored. Psychological and neuromuscular mechanisms can be involved, such as a better activation of the lumbar multifidus, which represents one possibility.

Objectives

To determine the following: (1) the effect of an LSEP on lumbar multifidus muscle thickness and activation, as measured with rehabilitative ultrasound imaging (RUSI), in patients with low back pain (LBP); (2) the correlation between RUSI measures and any change in clinical outcomes following the LSEP; and (3) the reliability of RUSI measures in control subjects over 8 weeks.

Design …

Trunk Postural Adjustments: Medium-Term Reliability And Correlation With Changes Of Clinical Outcomes Following An 8-Week Lumbar Stabilization Exercise Program, Jean-Alexandre Boucher, Richard Preuss, Sharon M. Henry, Marilee Nugent, Christian Larivière

Études primaires

Background

Low back pain (LBP) has been previously associated with delayed anticipatory postural adjustments (APAs) determined by trunk muscle activation. Lumbar stabilization exercise programs (LSEP) for patients with LBP may restore the trunk neuromuscular control of the lumbar spine, and normalize APAs. This exploratory study aimed at testing the reliability of EMG and kinematics-based postural adjustment measures over an 8-week interval, assessing their sensitivity to LBP status and treatment and examining their relationship with clinical outcomes.

Methods

Muscle activation of 10 trunk muscles, using surface electromyography (EMG), and lumbar angular kinematics were recorded during a rapid arm-raising/lowering task. Patients with …

Trunk Postural Balance And Low Back Pain: Reliability And Relationship With Clinical Changes Following A Lumbar Stabilization Exercise Program, Ali Shahvarpour, Dany H. Gagnon, Richard Preuss, Sharon M. Henry, Christian Larivière

Études primaires

Lumbar stabilization programs reduce pain and disability, but the mechanisms of action underlying this treatment are unknown. Trunk postural control during unstable sitting represents a surrogate measure of motor control mechanisms involved to maintain the dynamic stability of the spine. This exploratory study aimed to determine the reliability of trunk postural control measures over an 8-week interval, their sensitivity to low back pain status and treatment and their relationship with clinical outcomes. Trunk postural control measures were determined in patients with low back pain before and after an 8-week lumbar stabilization exercise program. Healthy controls were assessed over the same …

Effects Of Motion Segment Simulation And Joint Positioning On Spinal Loads In Trunk Musculoskeletal Models, F. Ghezelbash, A. H. Eskandari, A. Shirazi-Adl, N. Arjmand, Z. El Ouaaid, A. Plamondon

Études primaires

Musculoskeletal models represent spinal motion segments by spherical joints/beams with linear/nonlinear properties placed at various locations. We investigated the fidelity of these simplified models (i.e., spherical joints with/without rotational springs and beams considering nonlinear/linear properties) in predicting kinematics of the ligamentous spine in comparison with a detailed finite element (FE) model while considering various anterior-posterior joint placements. Using the simplified models with different joint offsets in a subject-specific musculoskeletal model, we computed local spinal forces during forward flexion and compared results with intradiscal pressure measurements. In comparison to the detailed FE model, linearized beam and spherical joint models failed to …

The Effect Of Wearing A Lumbar Belt On Biomechanical And Psychological Outcomes Related To Maximal Flexion-Extension Motion And Manual Material Handling, Ali Shahvarpour, Richard Preuss, Michael J.L. Sullivan, Alessia Negrini, Christian Larivière

Études primaires

Workers with low back pain (LBP) may benefit from wearing a lumbar belt (LB), but the biomechanical and psychological mechanisms involved are not fully understood. Two types of flexible LB (extensible and non-extensible) were compared to a control condition (no LB) regarding pain-related (pain, fear of pain and catastrophizing) and biomechanical (range of motion – ROM) outcomes related to two tasks: maximal trunk flexion-extension and manual material handling. Healthy controls and participants with LBP were tested. During both tasks, the two LBs reduced the lumbar ROM in participants with LBP in the same way as healthy controls. This was observed …

Difference Between Male And Female Workers Lifting The Same Relative Load When Palletizing Boxes, André Plamondon, Christian Larivière, Denys Denis, Hakim Mecheri, Iuliana Nastasia

Études primaires

A few biomechanical studies have contrasted the work techniques of female and male workers during manual material handling (MMH). A recent study showed that female workers differed from males mostly in the strategy they used to lift 15-kg boxes from the ground, especially regarding task duration, knee and back postures and interjoint coordination. However, the lifting technique difference observed in females compared to males was perhaps due to a strength differences. The objective of this study was to test whether female workers would repeat the same lifting technique with a load adjusted to their overall strength (females: 10 kg; males: …

Accuracy And Repeatability Of Single-Pose Calibration Of Inertial Measurement Units For Whole-Body Motion Analysis, Xavier Robert-Lachaine, Hakim Mecheri, Christian Larue, André Plamondon

Études primaires

Portable inertial measurement units (IMUs) are suitable for motion analysis outside the laboratory. However, IMUs depend on the calibration of each body segment to measure human movement. Different calibration approaches have been developed for simplicity of use or similarity to laboratory motion analysis, but they have not been extensively examined. The main objective of the study was to determine the accuracy and repeatability of two common single-pose calibrations (N-pose and T-pose) under different conditions of placement (self-placement and passive placement), as well as their similarity to laboratory analysis based on anatomical landmarks. A further aim of the study was to …

Obesity And Obesity Shape Markedly Influence Spine Biomechanics: A Subject-Specific Risk Assessment Model, Farshid Ghezelbash, Aboulfazl Shirazi-Adl, André Plamondon, Navid Arjmand, Mohammad Parnianpour

Études primaires

Underlying mechanisms of obesity-related back pain remain unexplored. Thus, we aim to determine the effect of obesity and its shapes on the spinal loads and the associated risks of injury. Obesity shapes were initially constructed by principal component analysis based on datasets on 5852 obese individuals. Spinal loads, cycles to vertebral failure and trunk stability margin were estimated in a subject-specific trunk model taking account of personalized musculature, passive ligamentous spine, obesity shapes, segmental weights, spine kinematics and bone mineral density. Three obesity shapes (mean and extreme abdominal circumferences) at three body weights (BWs) of 86, 98 and 109 kg …

The Effect Of An 8-Week Stabilization Exercise Program On The Lumbopelvic Rhythm And Flexion-Relaxation Phenomenon, Ali Shahvarpour, Sharon M. Henry, Richard Preuss, Hakim Mecheri, Christian Larivière

Études primaires

Background

Lumbar stabilization exercise programs should normalize the aberrant movements patterns often observed in patients with low back pain. This study aimed to determine the effect of an 8-week lumbar stabilization program on EMG/kinematics measures of the aberrant movement patterns in such patients. A secondary goal was to assess the 8-week test-retest reliability of these measures.

Methods

The patients followed an 8-week lumbar stabilization program while no intervention was carried out on the controls. Before and after this period, kinematics of the spine along with the EMG of paraspinal muscles were recorded during trunk maximal flexion-extension. ANOVAs tested the effect …

Use Of The Novel Derivatizing Agent 1,8-Diaminonapthalene With The Cip10 Sampler To Measure 4,4'-Methylene Diphenyl Diisocyanate Atmospheres, Silvia Puscasu, Simon Aubin, Philippe Sarazin, Lucile Richard, Mark Spence, Sébastien Gagné

Études primaires

DAN is a novel derivatizing agent for isocyanate sampling which targets total reactive isocyanate group (TRIG). Field evaluations have been conducted for 4,4’-Methylene diphenyl diisocyanate (MDI) sampling using DAN as the derivatizing agent in a CIP10. The perimidone formed, selective of TRIG, was analyzed in laboratory by liquid chromatography coupled to tandem mass spectrometry. Workplaces using MDI-based polyurethane spray foam and MDI wood product binder were studied. Each study compared the data obtained between the CIP10/DAN, the CIP10/MP, and a reference method. As a first evaluation, the CIP10/DAN sampled simulated MDI spray foam atmosphere in parallel with impingers (reference method) …

Effect Of Local Magnetic Field Disturbances On Inertial Measurement Units Accuracy, Xavier Robert-Lachaine, Hakim Mecheri, Christian Larue, André Plamondon

Études primaires

Inertial measurement units (IMUs), a practical motion analysis technology for field acquisition, have magnetometers to improve segment orientation estimation. However, sensitivity to magnetic disturbances can affect their accuracy. The objective of this study was to determine the joint angles accuracy of IMUs under different timing of magnetic disturbances of various durations and to evaluate a few correction methods. Kinematics from 12 individuals were obtained simultaneously with an Xsens system where an Optotrak cluster acting as the reference system was affixed to each IMU. A handling task was executed under normal laboratory conditions and imposed magnetic disturbances. Joint angle RMSE was …

Validation Of Inertial Measurement Units With An Optoelectronic System For Whole-Body Motion Analysis, Xavier Robert-Lachaine, Hakim Mecheri, Christian Larue, André Plamondon

Études primaires

The potential of inertial measurement units (IMUs) for ergonomics applications appears promising. However, previous IMUs validation studies have been incomplete regarding aspects of joints analysed, complexity of movements and duration of trials. The objective was to determine the technological error and biomechanical model differences between IMUs and an optoelectronic system and evaluate the effect of task complexity and duration. Whole-body kinematics from 12 participants was recorded simultaneously with a full-body Xsens system where an Optotrak cluster was fixed on every IMU. Short functional movements and long manual material handling tasks were performed and joint angles were compared between the two …

A Biomechanical Comparison Between Expert And Novice Manual Materials Handlers Using A Multi-Joint Emg-Assisted Optimization Musculoskeletal Model Of The Lumbar Spine, Denis Gagnon, André Plamondon, Christian Larivière

Études primaires

Expertise is a key factor modulating the risk of low back disorders (LBD). Through years of practice in the workplace, the typical expert acquires high level specific skills and maintains a clean record of work-related injuries. Ergonomic observations of manual materials handling (MMH) tasks show that expert techniques differ from those of novices, leading to the idea that expert techniques are safer. Biomechanical studies of MMH tasks performed by experts/novices report mixed results for kinematic/kinetic variables, evoking potential internal effect of expertise. In the context of series of box transfers simulated by actual workers, detailed internal loads predicted by a …

Effects Of Sex, Age, Body Height And Body Weight On Spinal Loads: Sensitivity Analyses In A Subject-Specific Trunk Musculoskeletal Model, F. Ghezelbash, A. Shirazi-Adl, N. Arjmand, Z. El-Ouaaid, A. Plamondon, J. R. Meakin

Études primaires

Subject-specific parameters influence spinal loads and the risk of back disorders but their relative effects are not well understood. The objective of this study is to investigate the effects of changes in age (35–60 years), sex (male, female), body height (BH: 150–190 cm) and body weight (BW: 50–120 kg) on spinal loads in a full-factorial simulation using a personalized (spine kinematics, geometry, musculature and passive properties) kinematics driven musculoskeletal trunk finite element model. Segmental weight distribution (magnitude and location along the trunk) was estimated by a novel technique to accurately represent obesity. Five symmetric sagittal loading conditions were considered, and …

Implementation And Evaluation Of An Analytical Method For A Novel Derivatizing Agent To Measure 4,4'-Methylene Diphenyl Diisocyanate Atmospheres, Silvia Puscasu, Simon Aubin, Mark Spence, Sébastien Gagné

Études primaires

Accurate measurement of 4,4'-methylene diphenyl diisocyanate (MDI) atmospheres is a challenge since the molecule is both chemically reactive and likely to be present in aerosol form when heated and sprayed because of its low vapor pressure. Meeting this challenge requires optimizing both the sampling device used and the derivatization agent employed to stabilize the isocyanate functional group. This study describes the use of a novel derivatization reagent for isocyanate sampling to address the challenge of MDI aerosol exposure sampling. Like most conventional derivatizing agents for isocyanates, 1,8-diaminonapthalene (DAN) reacts with isocyanate functional groups to form a urea. However, unlike other …

Identification Of Methylene Diphenyl Diisocyanate Thermal Degradation Products In A Generation Chamber By Liquid Chromatography Coupled With Tandem Mass Spectrometry, Sébastien Gagné, Yves Cloutier

Études primaires

Isocyanate thermal degradation characterization by liquid chromatography coupled with electrospray tandem mass spectrometry has been performed to elucidate the methylene diphenyl diisocyanate (MDI) thermal degradation structure emitted in a generation chamber using a temperature between 50°C and 180°C to produce MDI vapors. [M+H]⁺ ions containing an isocyanate functional group were studied by tandem mass spectrometry. The [M+H]⁺ ion analyses based on the combination of full scans and precursor ion scans were useful for identifying all structures. The compounds emitted were identified and validated as a mixture of compounds containing amine and isocyanate functions. Residual MDI, methylene diphenyl amino-isocyanate, …

Subject-Specific Biomechanics Of Trunk: Musculoskeletal Scaling, Internal Loads And Intradiscal Pressure Estimation, F. Ghezelbash, A. Shirazi-Adl, N. Arjmand, Z. El-Ouaaid, A. Plamondon

Études primaires

Development of a subject-specific computational musculoskeletal trunk model (accounting for age, sex, body weight and body height), estimation of muscle forces and internal loads as well as subsequent validation by comparison with measured intradiscal pressure in various lifting tasks are novel, important and challenging. The objective of the present study is twofold. First, it aims to update and personalize the passive and active structures in an existing musculoskeletal kinematics-driven finite element model. The scaling scheme used an existing imaging database and biomechanical principles to adjust muscle geometries/cross-sectional-areas and passive joint geometry/properties in accordance with subjects’ sex, age, body weight and …

Two Related Occupational Cases Of Legionella Longbeachae Infection, Quebec, Canada, Marianne Picard-Masson, Élisabeth Lajoie, Judith Lord, Cindy Lalancette, Geneviève Marchand, Éric Levac, Marc-André Lemieux, Patricia Hudson, Louise Lajoie

Études primaires

Two patients with no exposure to gardening compost had related Legionella longbeachae infections in Quebec, Canada. Epidemiologic investigation and laboratory results from patient and soil samples identified the patients’ workplace, a metal recycling plant, as the likely source of infection, indicating a need to suspect occupational exposure for L. longbeachae infections.

An Axisymmetric Finite Element Model To Study The Earplug Contribution To The Bone Conduction Occlusion Effect, Martin K. Brummund, Franck Sgard, Yvan Petit, Frédéric Laville, Hugues Nélisse

Études primaires

An axisymmetric linear elasto-acoustic finite element (FE) model of an occluded human external ear is proposed to simulate the bone conduction occlusion effect (OE). The model consists of a cylindrical ear canal cavity surrounded by layers of biological tissues (skin, cartilage and bone) in which an earplug is inserted. Geometrical and material properties are taken from the literature. OEs are predicted for foam and silicone earplug FE-models using COMSOL Multiphysics (COMSOL®, Sweden). The FE-model is shown to predict the experimental OE measured in two healthy human reference groups wearing foam or silicone earplugs, satisfactorily. Deviations between model and experiment are …

Comparison Between The Asset Ez4 Nco And Impinger Sampling Devices For Aerosol Sampling Of 4,4′-Methylene Diphenyl Diisocyanate In Spray Foam Application, Silvia Puscasu, Simon Aubin, Yves Cloutier, Philippe Sarazin, Huu Van Tra, Sébastien Gagné

Études primaires

4,4′-methylene diphenyl diisocyanate (MDI) aerosol exposure evaluation in spray foam insulation application is known to be a challenge. Current available techniques are either not user-friendly or are inaccurate or are not validated for this application. A new sampler has recently been developed to address the user-friendliness issues with other samplers: the ASSET EZ4-NCO, but the use of this sampler in spray foam insulation applications has not been demonstrated or validated. Because of this, the current work was undertaken to provide a comparison of the ASSET sampler with an impinger method, considered to be the best available method in the context …

Determination Of Triglycidyl Isocyanurate From Air Samples By Ultra-Performance Liquid Chromatography Coupled With Coordination Ion Spray Mass Spectrometry, Sébastien Gagné, Marielle Carrier, Simon Aubin

Études primaires

Rationale

Ultra-performance liquid chromatography (UPLC) coupled with coordination ion spray tandem mass spectrometry was used for the analysis of air samples containing triglycidyl isocyanurate. The method is not affected by any chromatographic interference and the filter extract is compatible with the UPLC system, as opposed to approaches using high-performance liquid chromatography coupled with ultraviolet detection and gas chromatography coupled with mass spectrometry.

Methods

Accu-cap^™ filters that had sampled triglycidyl isocyanurate were extracted using a mixture of acetonitrile/acetone (95/5) diluted with 3 volumes of water and were then analyzed. The mass spectrometry method uses sodium as the alkali adduct complexing …